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 m$m&m'$wt t 
 
 
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LIBRARY 
 
 OF THE 
 
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PRODUCER GAS. 
 
THE 
 
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 PUBLISHING CO 
 
PRODUCER GAS. 
 
 A SKETCH OF 
 
 THE PROPERTIES. MANUFACTURE, 
 5EOUS FUEL. 
 
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 on terms which do not allow them to 
 a discount to the public. 
 
 F.LC., F.C.S., 
 
 .'and Technical College; 
 
 Past-President West of Scot' and Iron and Steel Institute; 
 Author of "Fuel," "The Metallurgy of Iron and Steel," &c., &c. 
 
 PRICE, 1Os. NET. 
 
 MANCHESTER : 
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SCIENTIFIC 
 
 PUBLISHING CO 
 
PRODUCER GAS. 
 
 A SKETCH OF 
 
 THE PROPERTIES, MANUFACTURE, 
 AND USES OF GASEOUS FUEL. 
 
 BY 
 
 A. HUMBOLDT SEXTON, F.I.C., F.C.S., 
 
 Professor of Metallurgy in the Glasgow and West of Scotland Technical College . 
 
 Past-President West of Scotland Iron and Steel Institute; 
 Author of " Fuel" " The Metallurgy of Iron and Steel," <&c., <bc. 
 
 PRICE, 1Os. NET. 
 
 MANCHESTER : 
 THE SCIENTIFIC PUBLISHING COMPANY. 
 
 [ALL RIGHTS RESERVED.] 
 
... 
 
 . 
 
 BOOKS BY THE SAME AUTHOR. 
 
 ELEMENTARY INORGANIC CHEMISTRY. 4th Edition. 2/6. 
 
 A MANUAL OF QUALITATIVE CHEMICAL ANALYSIS. 
 
 3rd Edition. 3/6. 
 
 A MANUAL OF QUANTITATIVE CHEMICAL ANALYSIS. 
 
 4th Edition. 3/- 
 
 HOME-WORK IN CHEMISTRY. I/- 
 AN ELEMENTARY TEXT BOOK OF METALLURGY. 3rd 
 
 Edition. 61- 
 
 FUEL AND REFRACTORY MATERIALS. 61- 
 
 THE CHEMISTRY OF MATERIALS OF ENGINEERING. 
 
 51- 
 
 THE METALLURGY OF IRON AND STEEL. I6/- 
 
 METALLURGICAL ANALYSIS AND ASSAYING (in con- 
 junction with Mr. E. L. BHEAD, Manchester). 10/6. 
 
 THE FIRST TECHNICAL COLLEGE. "A sketch of the 
 history of the Andersonian." 3/6. 
 
PREFACE. 
 
 IN 1902 the Author gave a course of lectures on 
 Producer Gas at the Technical College, Glasgow. These 
 attracted considerable attention, and it was requested 
 that they should be published. As there was no convenient 
 book dealing with the subject, the Author thought such a 
 one might be useful; so he has prepared this little book, 
 which is based on the notes of the lectures. Owing to 
 unavoidable circumstances, the publication has been some- 
 what delayed, but this has perhaps not been altogether a 
 disadvantage. 
 
 The subject of gaseous fuel has been attracting a 
 great amount of attention during the last few years, and 
 very important advances have been made. The use of 
 fuel gas is becoming every year more general, though the 
 Author feels that at present it is only in its infancy, and 
 that in the near future it will be used on a much larger 
 scale, and for many purposes. 
 
 Special attention has been given to the principles 
 on which the production of gaseous- fuel depends, as. 
 once these are mastered the practical questions as to 
 the best form and design of producer are quite simple. 
 Typical producers have been described, and in an appendix 
 some of the latest forms. The patented gas producers 
 are extremely numerous, and it is certain that many of 
 them involve no new principle or even important improve- 
 ment in detail, but it is advantageous to the student and 
 the practical man to know what has been done. 
 
 Many important branches of the subject are not 
 touched as, for instance, domestic heating as to have 
 dealt with them satisfactorily would have increased the 
 
 141384 
 
VI. PREFACE. 
 
 size of the book far beyond what is desirable. For the 
 same reason other topics are dealt with very briefly. 
 
 As changes are constantly taking place, the Author 
 will be much obliged to inventors or makers of gas plant 
 if they will inform him of any new design of plant they 
 may bring out, and he will also welcome details of the 
 results obtained, since increased information may lead to 
 the formation of sounder judgments on many points. He 
 will also welcome additional information on any of the 
 subjects dealt with, with a view of making a second 
 edition should such be called for a great improvement 
 on the first. 
 
 The best thanks of the Author are due to his colleague, 
 
 o ' 
 
 Dr. Gray, for looking through the proofs; to his assistant, 
 Mr. Claude A. Meiklejohn, for reading the proofs and 
 checking the calculations ; and to the many friends who 
 have assisted the work by the gift or loan of drawings, 
 by giving information as to work done, by permission to 
 reproduce published illustrations, and in many other ways. 
 
CONTENTS. 
 
 PAGE. 
 
 CHAPTER I. 
 
 Constituents of Fuel Gas The Air Variation of the 
 Volume of Gases with Changes of Pressure and Tem- 
 perature Calculation of the Percentage Composition of 
 Gases by Weight from the Composition by Volume 
 Amount of Air required for Combustion Volume of 
 Products of Combustion ... ... ... ... ... 1 
 
 CHAPTER II. 
 
 Thermal Units Heat of Combustion Calorific 
 Power Calculation of the Calorific Power of Fuels 
 Calorific Intensity Temperature of Combustion 
 Heat carried away by the Products of Combustion 
 Heating by Contact and by Radiation ... ... ... 15 
 
 CHAPTER III. 
 Natural Gas Coal Gas Oil Gas Acetylene ... 25 
 
 CHAPTER IV. 
 
 Simple Producer Gas Steam-enriched Producer Gas 
 Coal-enriched Producer Gas Carbon-dioxide in Pro- 
 ducer Gas Efficiency of a Gas Producer Loss of Heat 
 in Gas Producers ... ... ... ... ... ... 32 
 
 CHAPTER V. 
 
 Chimney-draught Producers The Overhead Cooling 
 Tube Forced-draught Producers Blowers Steam Jet 
 Blower Annular Jets Adjustable Jets Argand Blower 
 The Korting Blower The Granger Blower Amount 
 of Steam Required ... ... ... ... ... ... 46 
 
 CHAPTER VI. 
 
 Types of Producers Chimney-draught Producers 
 The Siemens Producer Closed-hearth Producers Bar- 
 bottom Producers The Thwaite Simplex Producer 
 The Dowson Producer Solid-bottom Producers The 
 Wilson Producer Water-bottom Producers The Daw- 
 son Producer The Duff Producer The Smith and 
 Wincott Producer Automatic Producers The Wilson 
 Automatic Producer The Taylor Producer Down- 
 draught Producers Korting's Producer The Blast Fur- 
 nace as a Gas Producer The Thwaite Cupola Producer 58 
 
Vlll. CONTENTS. 
 
 PAGE. 
 CHAPTER VII. 
 
 Mond Gas The Producer The Condensing Plant 
 The Products Cost of Working The Duff Plant ... 86 
 
 CHAPTER VIII. 
 
 Water Gas The Leeds Forge Plant The Lowe Pro- 
 ducer The Loomis and Loomis-Pettibone Producers 
 The Dellwik-Fleischer Process Water Gas 95 
 
 CHAPTER IX. 
 
 Conditions which must be Fulfilled by a Good Gas 
 Producer The Air Supply Speed of Gasification 
 Shape of Producers Sources of Loss of Heat in Gas Pro- 
 ducers Heating Steam and Air Quality of the Gas 
 Charging Producers Automatic Charging Ash Re- 
 moval Use of Coking Coal in Gas Producers Tar 
 Removal The Wilson Producer The Thwaite Twin 
 Duplex and Non-reversal * Producers The Duff- 
 Whitfield Producer Washing the Gas Ammonia 
 Recovery Cost of Gas ... ... ... ... ...Ill 
 
 CHAPTER X. 
 
 Use of Gaseous Fuel Firing Steam Boilers Fur- 
 naces Regenerative Furnaces The Siemens Furnace 
 The New Type Siemens Furnace The Gorman Furnace 
 The Weardale Furnace The Dunnachie Kiln The 
 Davis-Colby Kiln Gas Engines Control of Production 
 Estimation of Carbon-dioxide in Producer Gas and in 
 Flue Gases ... t 128 
 
 APPENDIX I. Tables : Tension of Water Vapour and 
 
 Properties of Gases ... ... ... ... 155 
 
 ,, II. Recent Forms of Gas Producer 158 
 
 III. Bibliography 211 
 
PRODUCER GAS. 
 
 CHAPTER I. 
 
 CONSTITUENTS OF FUEL GAS. THE AIR. VARIATION 
 OF THE VOLUMES OF GASES WITH CHANGES OF 
 PRESSURE AND TEMPERATURE. CALCULATION OF 
 THE PERCENTAGE COMPOSITION OF GASES BY 
 WEIGHT FROM THE COMPOSITION BY VOLUME. 
 
 GASES used as fuel are always prepared by the gasifi- 
 cation of solid fuel, usually coal or coke, either by 
 destructive distillation as in the manufacture of coal gas, 
 by incomplete combustion as in the production of coke 
 producer gas and water gas, or by a combination of the 
 two methods, as in coal producer gas. In the first method 
 a gas rich in illuminating constituents is obtained con- 
 sisting almost entirely of combustible constituents, and a 
 large proportion of the fuel is left in the form of a solid 
 residue or coke ; in the two last, a gas of a different 
 character is obtained, and the whole of the fuel except the 
 ash is gasified. 
 
 Gas made by any of the methods is not a definite 
 compound, but a mixture of several gases in very varying 
 proportions. 
 
 As the same gases are present in all forms of fuel gas, 
 the character of the gas will depend on the proportions in 
 which these constituents are mixed ; and as the properties 
 of a mixture are always the mean of those of its con- 
 stituents, it is essential that the properties of the 
 individual constituent gases should be known in order that 
 those of the mixture may be understood and that the 
 influence of the separate constituents may be judged, and 
 also in order that an idea of the value and properties of 
 a gas may be formed from an analysis which gives the 
 proportions of its constituents. 
 
2 PRODUCER GAS. 
 
 The constituents of all fuel gases may be classified into 
 two groups : (1) Those which are combustible and which, 
 therefore, have a greater or less value in the gas ; and (2) 
 those which are not combustible, and which, therefore, 
 have no heating value, but only act as diluents. 
 
 The following are the most important gases, but 
 higher members of the hydrocarbon series, to which 
 marsh gas, ethylene, and acetylene belong, may also be 
 present : 
 
 (1) Combustible gases. 
 
 Hydrogen, H. 
 Carbon-monoxide, CO. 
 Marsh gas, methane, CH 4 . 
 Ethylene, C 2 H 4 . 
 Acetylene, C 2 H 2 . 
 
 (2) Diluents. 
 
 Nitrogen, N. 
 
 Carbon-dioxide C0 2 . 
 
 Oxygen, O. 
 
 In addition, there may be present combustible and 
 non-combustible vapours, such as tarry matters and some 
 other substances which may have considerable influence 
 on the quality of the gas, but which are not given in the 
 ordinary analysis of the gas, because they are condensed, 
 and thus removed in the preparation of the sample for 
 analysis. 
 
 COMBUSTIBLE GASES. 
 
 Hydrogen (H). Atomic weight, 1 ; mol. weight, 2. This 
 gas is always present in larger or smaller quantity. It is 
 found in considerable quantity in the products of the 
 destructive distillation of coal, and is therefore present in 
 coal gas. It is also liberated whenever steam comes in 
 contact with very hot carbon, carbon-monoxide or carbon- 
 dioxide being formed at the same time, according to the 
 temperature and the quantity of carbon present, thus 
 
 (1) C + H 2 O = CO + 2H. 
 
 (2) C + 2H 2 O = CO 2 + 4H. 
 
 It is colourless and odourless and very light ; indeed, it is 
 the lightest known substance. It is less than T J as 
 heavy as air; its specific gravity (air = 1) being -06926 
 and 1 cub. ft. weighs at 0C. and 760 mm. bar, -00561bs., 
 or lib. occupies 178-57 cub. ft. Its specific heat is 2*414. 
 
PRODUCER GAS. 3 
 
 It is very readily combustible, and burns with a pale blue 
 almost non-luminous, flame. One pound evolves on com- 
 bustion 34,180 Centigrade units or 61,524 B.Th.U. 
 of heat. It is therefore one of the most valuable con- 
 stituents of fuel gas, but owing to its extreme lightness, 
 if present in large proportion, it makes the gas light and 
 bulky. One cubic foot only evolves 191 '4 C.U. or 344-5 
 B.Th.U. of heat on combustion. When it burns water is 
 formed 
 
 (3) 2H + O=H 2 O. 
 
 It requires eight times its own weight or half its own 
 volume of oxygen for combustion, and yields nine times 
 its own weight of water, which, if the temperature be 
 above 100 C., will occupy the same volume as the hydrogen 
 would do under the same conditions of temperature and 
 pressure. It requires about 2 - 4 times its own volume or 
 34 '78 times its own weight of air for complete combustion. 
 The influence of hydrogen in a gas is to make it light 
 and bulky, to add largely to its heating power, and, at 
 the same time, to increase very much the amount of air 
 required for combustion, and, since the specific heat of 
 steam is very high, also to increase the amount of heat 
 carried away in the products of combustion. 
 
 Carbon-monoxide (CO). Mol. weight, 27'93 (28). This is 
 one of the most important constituents of fuel gas. It is 
 colourless and odourless, and burns with a characteristic 
 pale blue, feebly luminous flame, forming carbon-dioxide 
 thus 
 
 (4) CO + O=CO 2 
 
 One pound evolves on combustion 2,430 C.U. or 4,374 
 B Th.U. of heat. It requires for complete combustion 
 57 times its own weight and half its own volume of 
 oxygen, and yields 1-57 times its own weight of carbon- 
 dioxide. The amount of air required is about 2 -4 times 
 its own volume, or 2 '48 times its own weight. 
 
 It is among the products of the destructive distillation 
 of coal, and is produced by the action of hot carbon on 
 carbon-dioxide, thus 
 
 (5) C0 2 + C=2CO 
 
 and of steam on hot carbon (equation 1). 
 
 As the specific heat of carbon-dioxide is only -2479, 
 the amount of heat carried away by the products of 
 combustion is not large. Its specific gravity (H=l) is 
 
4 PRODUCER GAS. 
 
 14 and (air=l) is -9671 ('968), and one cubic foot weighs 
 07811b 
 
 Marsh Gas (Methane CH 4 ). Mol. weight, 15'97 (16). 
 This is a colourless and odourless gas which occurs in 
 large quantity in natural gas. It is produced by the 
 decompositions by which vegetable matter passes into 
 coal, and is therefore often present in coal mines, where it 
 is known as fire-damp. It is among the products of the 
 destructive distillation of coal, and is therefore always 
 present in coal gas, though rarely in large quantity. Its 
 specific gravity (air ==1) is '5530, whence it is often 
 called light carburetted hydrogen. One cubic foot weighs 
 04471b. It burns readily with a slightly luminous 
 flame, forming carbon dioxide and water, thus 
 
 (6) CH 4 + 4 O == CO, + 2 H 2 0. 
 
 If the quantity of oxygen be insufficient for complete 
 combustion it yields carbon monoxide, hydrogen, and 
 lower hydrocarbons with but little free carbon, so that 
 little or no smoke is produced. It requires for complete 
 combustion four times its own weight and twice its own 
 volume of oxygen, or 17 '3 times its weight and 9 '5 2 
 times its own volume of air. It yields 2*25 times its own 
 weight of water and 2-75 times its own weight of carbon 
 dioxide. Its calorific power is 13,062 C.U., or 23,512 
 B.Th.U. 
 
 Ethylcnc (C 2 H 4 ). Mol. weight, 27*94 (28). This gas is 
 present in considerable quantity in gases such as coal gas 
 produced by destructive distillation. It is colourless and 
 odourless, burns very easily, with a very luminous flame, 
 which becomes readily smoky. It is the chief illuminating 
 constituent of coal, and similar, gases. On complete com- 
 bustion it yields water and carbon dioxide. 
 
 (7) C 2 H 4 + 6 O=2 CO 2 + 2 H 2 
 
 It requires for complete combustion 3 '42 times its own 
 weight and three times its own volume of oxygen, or 
 14-87 its own weight, and 14*28 times its own volume of 
 air. It yields twice its own volume of carbon dioxide and 
 twice its own volume of steam. With an insufficient 
 supply of air it burns with a very smoky flame. Its 
 specific gravity (air=l) is -9784, and a cubic foot weighs 
 07841bs. Its specific heat is -4040. It yields on complete 
 combustion 11,143 C.U. or 20,057 B.Th.U. of heat. 
 
PRODUCER GAS. 5 
 
 Acetylene (C 2 H 2 ). This is a colourless gas, having a 
 most unpleasant odour. It burns readily with a very 
 brilliant flame, and shows a great tendency to produce 
 smoke by the separation of carbon. 
 
 (8) C 2 H 2 + 5O == 2 CO 2 + H 2 O 
 
 It requires three times its own weight and 2*5 times 
 its own volume of oxygen for complete combustion. Its 
 specific gravity (air=l) is '9100, and a cubic foot weighs 
 07341bs. It is an unstable body, decomposing very 
 readily with evolution of heat, and is of little importance 
 as a fuel gas. 
 
 DILUENTS. 
 
 Nitrogen (N). Atomic weight 14 ; mol. weight 28. This 
 is a colourless and odourless gas, always present in fuel and 
 lighting gases. It is produced in small quantity by the 
 destructive distillation of nitrogenous organic matter, and 
 is therefore present in small quantities in coal, and similar, 
 gases. It forms a large percentage of the air, is therefore 
 always present in large quantity in gases produced by 
 incomplete combustion. Its specific gravity (air=l) is 
 9701, and one cubic foot weighs -07841bs. It is not 
 combustible, and has no influence on fuel gas, except to 
 act as a diluent. Its specific heat is -2438. 
 
 Carbon Dioxide (CO 2 ). Mol. weight 43-89 (44). This is 
 a colourless, odourless, non-combustible gas. It is produced 
 in small quantity by destructive distillation, and is there- 
 fore present in small quantity in coal gas. It is often 
 present in producer gas in considerable quantity, being 
 produced by the combustion of carbon. Its specific 
 gravity (air=l) is 1-5196; one cubic foot weighs -12271bs., 
 and its specific heat is -2163. In presence of excess of 
 carbon at high temperatures it is reduced to carbon 
 monoxide, thus 
 
 (9) CO 2 + C=2 CO. 
 
 Oxygen (O). This gas is never present in fuel gas 
 except by leakage after the gas has cooled, since at high 
 temperatures it would at once combine with the com- 
 bustible constituents of the gas. 
 
 Steam (H a O). Mol. weight, 17-97 (18). Water vapour is 
 always present in fuel gas, being produced by the 
 vaporisation of the moisture in the fuel, and it is always 
 among the products of destructive distillation, and it may 
 
6 PRODUCER GAS. 
 
 be produced by the combustion of hydrogen or hydro- 
 carbons owing to the leakage of air into the gas. At 
 temperatures above 100 C. the whole of the water will 
 be in the condition of vapour, and will behave exactly like 
 any other gas. At temperatures below 100 C. part of 
 the steam will condense, but a certain amount of water 
 vapour will always remain in the gas, the amount 
 depending on the temperature, as at every temperature 
 water can exist in the condition of gas or vapour till it 
 exerts a definite pressure. 
 
 Table I.* gives the proportions of steam and water 
 vapour that will be present in a given space at each 
 degree from C. to 100 C. 
 
 The specific gravity of steam or water vapour at and 
 760mm. is - 622(air=l), and one cubic foot weighs '05021bs. 
 
 As its specific heat is '4805, the presence of water 
 vapour causes a large amount of heat to be carried away 
 in the products of combustion. 
 
 There may also be present a considerable amount of 
 condensed water in the form of fine globules or mist. 
 
 Tarry Matters. These are mostly dense hydrocarbons of 
 very uncertain composition, which condense at moderate 
 temperatures to tarry and oily liquids. They burn with 
 a luminous, often smoky, flame. On being passed over 
 red hot coke or red hot brickwork they are broken up 
 into carbon, which is deposited, and permanent gases, 
 largely marsh gas and hydrogen. The influence of tarry 
 matters on the quality of gas will be discussed later. 
 
 THE AIR. 
 
 In practice, fuels are always burnt in air. The air 
 consists of a mixture of oxygen and nitrogen with small 
 quantities of other substances, some inert gases resembling 
 nitrogen, which have been recently discovered, but which, 
 since they have no influence on combustion, can be 
 neglected, carbon dioxide, very minute quantities of 
 ammonia, acid gases, &c., and a considerable quantity 
 of water vapour. For all practical purposes dry air may 
 be taken as containing 
 
 By weight. By volume. 
 
 Oxygen 23 ... 21 
 
 Nitrogen ... ... 77 ... 79 
 
 100 100 
 
 * For Table I see Appendix. 
 
PRODUCER GAS. 7 
 
 These proportions are very nearly constant, and the 
 other constituents are present in such small quantities as 
 to be of no importance when the air is considered 
 merely as a supporter of combustion. Carbon dioxide, 
 the impurity present in largest proportion, rarely exceeds 
 04 per cent. 
 
 The amount of moisture present is very variable. The 
 amount of water vapour which the air is capable of 
 holding at different temperatures is given in Table I, but 
 the air is rarely saturated, so that the amount of water 
 present at any time can only be guessed unless it be 
 determined by analysis, or unless the dew point, i.e., the 
 temperature at which the air would be saturated with the 
 moisture present, be determined by a hygrometer. 
 
 The presence of water does not alter the proportions 
 in which the constituents of the air are present, but 
 simply displaces some of the air, the relative volumes of 
 air and water being proportional to the pressure they 
 exert. 
 
 Thus for instance air at 15C. saturated with 
 moisture would contain in 100 volumes 
 Water vapour ... 1*67 
 
 Air 98-33 { Ox ^ en > 20 ' 65 
 
 5 \ Nitrogen, 77-68 
 
 Variation in the Volumes of Gases. It must be borne in mind 
 that the volume of a gas changes very considerably with 
 changes of temperature and pressure, and therefore that 
 when weights of gases are compared it must always be 
 under the same conditions of temperature and pressure. 
 As, however, all gases are affected in the same proportion, 
 the percentage composition by weight or volume is not 
 altered, however much the actual weight of a given volume 
 may vary. 
 
 When weights of gases are given it is always the 
 weight of a standard volume under normal temperature 
 and pressure, i.e., C. (32 F.), and 760 mm. of mercury 
 (30") barometric pressure. Volumes of gases at any other 
 temperature or pressure must always be reduced by 
 calculation to these conditions. 
 
 The pressure to which a gas is subjected is measured 
 either by the height of a column of mercury which it will 
 support, measured in inches or millimetres, or, what is the 
 same thing, if it be at the atmospheric pressure, the 
 
8 PRODUCER GAS. 
 
 height at which the barometer stands, or by the pressure 
 in pounds or other units per square inch to which it is 
 subjected above the atmospheric pressure*. 
 
 Boyle's Law. The law according to which the volume 
 of a gas varies with the pressure to which it is subjected 
 is called Boyle's law, and may be simply stated 
 
 " The volume occupied by a given mass of any gas is 
 inversely proportional to the pressure to which it is sub- 
 jected." Or if it is put into the form of an equation : If V 
 be the volume of gas at pressure P, and V be the volume 
 at pressure P f . 
 
 Then F : F ; : P' : P. 
 
 Whence F = V'P'jP and V = VP/P'. 
 
 From these equations the required volumes are easily 
 calculated. 
 
 Example 1. A mass of gas occupies a volume of 
 10 cub. ft. when the barometer stands at 30in., what 
 volume will it occupy if the pressure falls to 29in. ? 
 Obviously with decreased pressure the volume will be 
 larger. 
 
 OA 
 
 Example 2. A mass of gas occupies a volume of 
 10 cub. ft. when the pressure is 29in.. what volume will it 
 occupy at 30in. ? Obviously the volume will be less. 
 
 9Q 
 
 F=10 x ^ = 9-67 cub. ft. 
 oU 
 
 Example 3. A volume of gas occupies 100 cub. ft. 
 at atmospheric pressure, what volume will it occupy at a 
 
 * Atmospheric pressure is always measured by the height of the column 
 of mercury which it will sustain, this being called the barometric pressure. 
 It may be measured either in inches or millimetres, and the one is very 
 easily converted into the other. 
 
 (1) To convert inches into millimetres, multiply by 25'4. 
 
 (2) To convert millimetres into inches, multiply by 0'03937 = about A. 
 The barometric pressure measured in inches, multiplied by - 4908, will 
 
 give the pressure in pounds per square inch. 
 
 The barometric pressure in millimetres, multiplied by 0'01932, will give 
 the pressure in pounds per square inch. 
 
 In some cases the pressure is measured in inches of water. 
 
 The specific gravity of mercury (water = 1) is 13'58, so that 
 To convert pressure measured in inches of merciiry into pressure measured 
 in inches of water, multiply by 13 '58. 
 
 To convert pressure in inches of water into pressure in inches of mercury, 
 multiply by 0'07364. 
 
PRODUCER GAS. 9 
 
 pressure of 51bs. per square inch above atmospheric 
 pressure ? Here again the volume will obviously be less. 
 T7 , 100 x 15 1500 
 
 -T5T5- -20- !=75cub ' ft - 
 
 As the volume varies inversely as the pressure it is 
 quite evident that the density, that is, the weight of a 
 given volume, must vary directly as the pressure, so that if 
 
 D be the density at a pressure P 
 and D f P' 
 
 D : D' :: P : P 
 and D=D' x PjP and D'=D x P '/P 
 
 Example 4. A cubic foot of air weighs -08071b. 
 when the pressure is 760mm., what will be the weight of 
 a cubic foot under a pressure of 900mm. Obviously the 
 weight will be greater. 
 
 Charles' Law. The law which connects the change of 
 volume of a gas with change of temperature is known as 
 Charles' law. It may be stated in several ways, the 
 simplest probably being as follows : 
 
 Gases expand ^1^ of their volume at C. for each 
 1 C. rise of temperature, and I T of their volume at 32Fah. 
 for each 1 Fah. rise of temperature, so that 
 
 273 volumes at C. 491 volumes at 32 Fah. 
 
 273 + 1 at 1 C. 491 + 1 at 33 Fah. 
 
 273 + 2 at 2 C. 491 + 2 at 34 Fah. 
 
 273 - 2 at - 2 C. 491 -- 2 at 30 Fah. 
 
 and in general 273 t 491 t at t Fah. 
 
 at t C. 
 
 A proportion, therefore, will give the volumes at any 
 temperature. If V be the volume at C., and V be the 
 volume at t C., 
 
 then V : V : : 273 : 273 + t 
 
 (273 
 
 V = ' 
 
 273 
 
 x 273 
 
 273 + t 
 
 Example 5. A mass of gas occupies a volume of 
 100 cub. ft. at 20 C., what volume will it occupy at C. ? 
 
10 PRODUCER GAS. 
 
 v 100 x 273 27300 
 
 273 + 20 : -293-= =93-17 cub. ft. 
 
 A temperature 273 below C. or 491-32=459 
 below Fah. is called the absolute zero, and temperatures 
 measured from this point are called absolute temperatures. 
 So that the absolute temperature in C. degrees will be the 
 temperature measured on the ordinary scale + 273, and 
 similarly the absolute temperature in Fah. degrees will be 
 the ordinary temperature + 459. From the equations 
 given above it follows that the volume of gas is propor- 
 tional to its absolute temperature. 
 
 As the volume is directly, the density or weight of a 
 given volume will obviously be inversely as the absolute 
 temperature. 
 
 When corrections have to be made for both tempera- 
 ture and pressure, one correction may be made first, and 
 then the other, using the corrected volumes as the starting 
 point, or both corrections may be made together. 
 
 Example 6. A mass of gas occupies 100 cub. ft. at 
 10 C. and 750mm. bar., what will its volume be at 
 Q C. and 760 mm. bar. ? 
 
 (1) Taking the pressure first. As the pressure is 
 greater the volume will be less. 
 
 760 : 750 : : 100 : x 
 
 = 98-68 ' 
 
 (2) As the temperature is less the volume will also be 
 less. 
 
 273 + 10 : 273 : : 98'68 : x 
 273 x 98-68 
 273 + 10 : 95 ' 19 
 
 or the two equations may be combined and worked as a 
 compound proportion. 
 
 760 : 750 \ 
 
 283 : 273 J : : J 
 
 _ 750 x 273 x 100 
 
 760 x 283 
 
 The student should make himself quite familiar with 
 these methods of calculation.* 
 
 *See the author's "Home Work on Chemistry." Hall, Is. 
 
PRODUCER GAS. 
 
 11 
 
 Calculation of the Composition of Gases by Weight. Analyses 
 of gases are almost invariably stated in percentage by 
 volume, since gases are usually measured and not weighed. 
 For many purposes this is quite convenient, but it is 
 often necessary to calculate the percentage composition by 
 weight, and this can be readily done from an analysis 
 by volume using the data already given. 
 
 An example will make the method quite clear. The 
 following figures represent the composition of a sample of 
 producer gas by volume : 
 
 Hydrogen 
 
 Marsh gas 
 
 Ethylene ... 
 
 Carbon monoxide . 
 
 Oxygen 
 
 Carbon dioxide ... 
 
 Nitrogen ... 
 
 100-00 
 
 If we assume the total 100 to stand for 100 cub. ft. then 
 the percentage of each constituent will stand for cubic 
 feet in the hundred, and by multiplying these figures by 
 the weight of 1 cub. ft. (see above) the weight of each 
 constituent in 100 cub. ft. will be obtained. 
 
 9-601 
 3-60 1 
 101 
 
 21-60 J 
 1-50] 
 5-00 
 58-60 J 
 
 1 Combustible, 
 34-90. 
 
 Diluent 
 65-10 
 
 Hydrogen 
 Marsh gas 
 Ethylene 
 Carbon monoxide 
 Oxygen 
 
 Carbon dioxide 
 Nitrogen 
 
 9-60 
 3-60 
 10 
 21-60 
 1-50 
 5-00 
 58-60 
 
 X 
 
 x 
 
 X 
 X 
 
 x 
 x 
 x 
 
 0056 
 0447 
 0784 
 0781 
 0893 
 1227 
 0784 
 
 05371b. 
 
 16091b. 
 
 00781b. 
 l-68691bs. 
 
 13391b. 
 
 61351b. 
 4-59421bs. 
 
 100 cub. ft. = 7-25091bs. 
 One cubic foot therefore weighs -0725091b. 
 
 From these figures the percentage composition by 
 weight can be easily calculated. 
 
 Thus : Of hydrogen 7'25091bs. of the gas contains 
 05371b., so that the amount in lOOlbs. will be 
 
 0537 x 100 *. 
 
12 PRODUCER GAS. 
 
 Working out the other items in the same way 
 
 Per cent, by weight. 
 
 Hydrogen ... ... ... ... -74 
 
 Marsh gas ............ 2-22 
 
 Ethylene .......... \. -11 
 
 Carbon monoxide ... ... ... 23*27 
 
 Oxygen ... ... ... ... 1*85 
 
 Carbon dioxide ... ... ... 8*47 
 
 Nitrogen ............ 63*34 
 
 100-00 
 
 If it be not desired to obtain the weight of 100 cub. ft., 
 but only the percentage composition by weight, the result 
 can be obtained more simply by multiplying the per- 
 centage, of each gas, by volume by its specific gravity, 
 and then working out the percentage as before. As the 
 specific gravity of a gas is always half its molecular 
 weight, these numbers using the approximate molecular 
 weights, which are always round numbers can be used. 
 It must be noted that for various reasons the densities of 
 gases, as deduced from their chemical composition, do not 
 always agree exactly with the figures determined by direct 
 experiment. The former are taken in most of the calcula- 
 tions given here. 
 
 Per cent. 
 
 Hydrogen ... 9*60 x 1 = 9*60 = -74 
 
 Marsh gas ... 3-60 x 8 = 28'80 = 2-22 
 
 Ethylene ...... -10 x 14 = 140 = -11 
 
 Carbon monoxide... 21-60 x 14 = 302-40 === 23-32 
 
 Oxygen ...... 1-50 x 16 = 24-00 - 1-85 
 
 Carbon dioxide ... 5'00 x 22 = 110*00 == 8'48 
 
 Nitrogen ...... 58-60 x 14 = 820-40 = 63-27 
 
 The small percentage of hydrogen by weight compared 
 with its large percentage by volume is noteworthy. 
 
 Amount of Air required for Combustion. Since the air 
 is usually measured, not weighed, this can be obtained 
 from the volume composition of the gases. 
 
 The volume of oxygen required for the combustion of 
 each of the constituent gases has already been given, and 
 by multiplying the percentage of each gas by the volume 
 of oxygen required for the complete combustion of one 
 volume, taking the gas, the analysis of which has already 
 been given, and adding the results, the amount of oxygen 
 required for 100 cub. ft. will be obtained. 
 
PRODUCER GAS. 
 
 13 
 
 Gas by vol. 
 
 ... 9-60 x 
 ... 3-60 x 
 10 x 
 ... 21-60 x 
 ... 5-00 
 ... 58-60 
 1-50 
 
 2 
 3 
 
 Cubic feet. 
 
 Hydrogen 9'60 x -5 = 4'80 
 
 Marsh gas 3'60 x 2 --= 7-20 
 
 Ethylene -10 x 3 = '30 
 
 Carbon monoxide 21-60 x -5= 10-80 
 
 Carbon dioxide 
 
 Nitrogen 
 
 Oxygen 
 
 io~(M)0~ 23-10 
 Amount of oxygen required for combustion 
 
 of 100 cub. ft. ... ... 23-10 
 
 Less oxygen in gas ... ... ... ... 1*50 
 
 21-60 
 
 As air contains 21 per cent, by volume of oxygen, the 
 volume of air which will contain 2 1*60 parts of oxygen 
 will be 21-60/21 x 100 == 102-85 cub. ft. at C. and 
 760mm. bar., and this amount will therefore be required 
 for each 100 cub. ft. of gas at the same temperature and 
 pressure. In practice, an excess of 5 to 50 per cent, over 
 this amount must be allowed. 
 
 The same results could have been obtained from the 
 percentage by weight, but in that case the weight of air 
 would have been obtained. 
 
 The Volume and Weight of Products of Combustion. The 
 volume of the products of combustion can be easily 
 obtained, it being of course assumed that they leave the 
 furnace at a temperature above 100 C., so that the water 
 is in the form of steam. 
 
 
 
 Vol. of 
 water for 
 one part 
 by vol. of 
 gas. 
 
 Vol. of CO 2 
 
 for one 
 part 
 by vol. 
 of gas. 
 
 Vol. 
 H 2 O. 
 
 Vol. 
 C0 3 . 
 
 Hydrogen 
 Marsh gas 
 
 9-60 
 3-60 
 3-60 
 
 X 1 
 
 x2 
 
 X 1 
 
 9-60 
 7-20 
 
 3-60 
 
 Ethylene 
 
 10 
 10 
 
 x2 
 
 x2 
 
 20 
 
 20 
 
 Carbon monoxide 
 
 21-60 
 
 
 
 X 1 
 
 
 
 21-60 
 
 Carbon dioxide 
 
 5-00 
 
 
 
 
 
 
 
 5-00 
 
 Nitrogen 
 Oxygen 
 
 58-60 
 1-50 
 
 
 
 
 
 - 
 
 
 
 17-00 
 
 30-40 
 
14 PRODUCER GAS. 
 
 So that 100 cub. ft. of the gas will yield 
 
 Water (steam) 17-00 cub. ft. 
 
 Carbon dioxide ... ... 30*4 
 
 Nitrogen (from gas) ... ... 58*6 ,, 
 
 (from air) 81-25 
 
 Excess of air, say, 25^ N. ... 20-31 
 
 O. 5-40 
 
 Total products of combustion for 
 100 cub. ft. of gas at the same 
 temperature and pressure ... 212-96 
 The weight of the products of combustion can be 
 calculated from the volume thus obtained, or from the 
 percentage composition of the gas by weight, the latter 
 being in general the most convenient. 
 
 If the weight of the oxygen used be known, the 
 weight of the products of combustion can be easily 
 calculated. It will be the sum of the weights of the gas 
 consumed, the oxygen required for combustion, the 
 nitrogen mixed with this oxygen in the air, and the 
 excess of air mixed with the actual products of combustion. 
 In the case of the gas already considered the oxygen 
 required by weight for each lOOlbs. of gas will be 
 28*451bs. -l*851bs. present in the gas=26*601bs., and the 
 products of combustion for each lOOlbs. will be 
 Water ............ 11-77 
 
 Carbon dioxide ... ... 51-46 
 
 Nitrogen from gas ... ... 63*34 
 
 Nitrogen from air ... ... 89*04 
 
 o^o/ fN ... 22-26 
 25^ j Q 6>65 
 
 IT c 
 
 Excess of air 
 
CHAPTER II. 
 
 THERMAL UNITS. HEAT OF COMBUSTION. CALORIFIC 
 POWER. CALCULATION OF THE CALORIFIC POWER 
 OF FUELS. CALORIFIC INTENSITY. TEMPERATURE 
 OF COMBUSTION. HEAT CARRIED AWAY BY 
 PRODUCTS OF COMBUSTION. HEATING BY CONTACT 
 AND BY RADIATION. 
 
 EVERY chemical change is attended with either the 
 evolution or the absorption of heat, and when in 
 any chemical change the amount of heat evolved is 
 sufficient to cause the production of light, combustion is 
 said to take place. In some cases, however, the action 
 is complex, and whilst the ultimate result is heat evolu- 
 tion, there may be intermediate changes in which heat is 
 absorbed, and the final result will be the algebraic sum of 
 all the thermal changes that have taken place. The heat is 
 always measured in units, the unit being the amount of heat 
 required to produce some definite change, usually to heat 
 a given mass of material through a definite range of 
 temperature. There are thus three things to be selected 
 in order to determine the unit, viz., the substance to be 
 heated, the weight to be taken, and the temperature 
 through which it is to be raised. 
 
 The material used is always water ; the weight is lib., 
 1 gramme, or 1 kilogramme, according to the system of 
 weights being used, and the temperature is one degree on 
 either the Centigrade or the Fahrenheit scale. As it does 
 not follow that the amount of heat required to raise lib. of 
 water 1 will be the same at all parts of the scale, it is 
 necessary to define at what temperature the experiment is to 
 be made. The difference in the amount of heat required for 
 any ordinary range of temperature, say between to 
 20 C., is so small that for all practical purposes the 
 temperature may be disregarded. 
 
 Three units are in use : 
 
 (1) The amount of heat required to raise lib. of water 
 1C. This is called the centigrade unit (C.U.), 
 and will usually be used in this book. 
 
16 PKODUCER GAS. 
 
 (2) The amount of heat required to raise lib. of 
 water 1F. This is called the British thermal unit 
 (B.Th.U.), and is commonly used by engineers and other 
 practical men in this country. 
 
 It will be seen that in these two systems the weight of 
 water is the same, the degree being the only variable, and 
 therefore the value of the units must be directly 
 proportional to the degree used. As the centigrade degree 
 is larger than the Fahrenheit degree in the proportion of 
 9 : 5, the centigrade unit will bear the same ratio to the 
 Fahrenheit unit. 
 
 As an amount of heat expressed in any given set of 
 units will vary inversely as the size of the units, an 
 amount of heat expressed by x C.U. units will be 9/5 x 
 B.Th.U., and any amount of heat expressed by y B.Th.U. 
 will be expressed by 5/9 y C.U. 
 
 (3) The amount of heat required to raise one kilo- 
 gramme of water 1C. is called a calorie, and that required 
 to raise one gramme of water 1C. is called a gramme- 
 calorie. 
 
 As in most cases the fuel used will be weighed in the 
 same units as the water, the same number will express 
 either the C. U. or the calories. 
 
 Evaporative Power. Engineers very frequently express 
 amounts of heat by the quantity of water at 100C. (212F.) 
 which would be evaporated into steam at the same 
 temperature, thus eliminating the difference due to the use of 
 different thermometric scales. This is called the evaporative 
 power. In general an evaporative power of lib. = 537 
 C.U. or 966 B.Th.U., but, as will be seen below, the 
 relationship is not always quite so simple. 
 
 Heat of Combustion. The amount of heat evolved by any 
 chemical change, and therefore by the complete com- 
 bustion of a given weight of a combustible, is fixed 
 and definite, and is quite independent of the rate of 
 combustion, or any other circumstance, so that it is 
 possible to assign fixed heat values to the combustion 
 of any fuel of definite composition. The amount of heat 
 evolved by the combustion of one unit weight (pound, 
 kilogramme, or gramme) of any fuel is called its absolute 
 heating power, or calorific power, and is indicated by the 
 letters C.P. 
 
PRODUCER GAS. 17 
 
 Carbon. When carbon is burnt with a sufficient excess 
 of oxygen for the combustion to be complete, carbon 
 dioxide is formed, and each lib. of carbon in burning will 
 form 3flbs. of carbon dioxide, and will evolve 8,080 units 
 of heat or the C.P. of C (to C0 2 ) = 8,080 C.U. 14,544 
 B.Th.U. Carbon, however, can be burnt in two stages. 
 When the temperature is very high and the oxygen is 
 limited in quantity, or, what comes to the same thing, 
 when the carbon is in large excess, carbon monoxide is 
 formed C + = CO. The combustion of carbon to 
 carbon monoxide only yields about one-third the heat 
 which would be evolved if it were burnt to carbon dioxide. 
 C.P. of C (to CO) = 2,416 say, for all practical pur- 
 poses 2,400 C.U. = 4,320 B.Th.U. 
 
 The difference between the two amounts, i.e., the 8,080 
 and the 2,400 units, is evolved when the carbon monoxide 
 is burnt to carbon dioxide. Thus lib. of carbon forms 
 2 Jibs, of carbon monoxide, and evolves 2,400 C.U. ; 2^1bs. 
 of carbon monoxide forms 3f Ibs. of carbon dioxide, and 
 evolves 5,680 C.U. ; lib. of carbon burning to carbon 
 dioxide yields 3lbs. of the gas, and evolves 8,080 C.U. 
 
 As 2 Jibs, of carbon monoxide burning to carbon 
 dioxide gives 5,680 units of heat, lib. will give 5,680 -f- 
 2J = 2,434 = say, 2,400 C.U. ; so C.P. of carbon monoxide 
 (GO) burning to carbon dioxide C0 2 = 2,400 C.U. = 
 4,320 B.Th.U. 
 
 Carbon can be made to combine with many other 
 elements, and although the union cannot be brought about 
 directly it is possible to determine indirectly the amount of 
 heat evolved. For instance, lib. of carbon combining 
 with Jib. of hydrogen to form IJlbs. of Marsh gas (CH A ) 
 evolves 1,543 C.U., lib. of carbon combining with 
 lib. of hydrogen to form IJlbs. of ethylene (C^) 
 evolves 664 units, whilst lib. of carbon combining with 
 j^jyth its weight of hydrogen to form l^lbs. of acetylene 
 not only evolves no heat but absorbs 1,852 units. These 
 figures may be expressed. 
 
 Heating power of lib. C (to CH^) = 1543 + C.U.* 
 
 (to (7 2 # 4 ) = 664 + 
 (to C 2 ff 2 ) = 1852 - 
 The importance of these facts will be seen later 
 
 * The sign + in this connection indicates evolution of heat, and the 
 sign - absorption of heat. The sign ie placed after the figures 
 
18 PRODUCER GAS. 
 
 Hydrogen. One pound of hydrogen burning evolves 
 34,180 C.U., so that C.P. of H = 34,180 C.U. = 61,524 
 B.Th.U. 
 
 This is on the assumption that the water formed is 
 condensed, the temperature of the gases produced being 
 reduced below 100C., which is the condition under 
 which all thermo-chemical experiments are made. If the 
 products of combustion be kept above 100C., the steam 
 will be kept in the gaseous condition, and the heat evolved 
 will therefore be less by the amount of heat which the 
 steam would give up on condensation, i.e., the latent heat 
 of the steam. The latent heat of steam is 537 C.U., 
 or 966 B.Th.U., and, as each pound of hydrogen forms 
 91bs. of water, the heat thus not given out will be 
 537 x 9 = 4,833 C.U., or 8694 B.Th.U., so that C.P. of H 
 (above 100C.) = 34,180 - 4,833 - 29,347 C.U., or 
 61,524 - 8,694 = 52,830 B.Th.U., or,. in round numbers, 
 near enough for all practical purposes, 29,300 C.U. = 
 53,000 B.Th.U. 
 
 Calorific Power of Solid Fuels. The calorific power of a 
 solid fuel can be calculated from these data if it be 
 assumed that the elements in the fuel evolve the same 
 amount of heat which they would do if they were in 
 the free condition. This assumption is certainly not 
 correct, but is near enough to allow of comparative results 
 being obtained for ordinary fuels, as these are made up of 
 more or less unstable compounds which have been formed 
 without a very large absorption or evolution of heat. 
 Such fuels consist mainly of carbon and hydrogen, with 
 sometimes other combustible elements, such as sulphur, &c. 
 
 (1) The fuel contains carbon and hydrogen only. 
 
 Let C = the percentage of carbon and H the percen- 
 tage of hydrogen in the fuel, then if the products of 
 combustion be above 100C. 
 
 8080 C + 29300 H . f .. 
 C.P. = - r-r or if the steam be condensed 
 
 8080 C + 34180 H 
 
 "loo- 
 
 (2) If the fuel contains oxygen the case is a little 
 more complex. The oxygen is not present as free gas, 
 but is already in combination, so that it is evident that 
 the elements with which it is combined will be able to 
 
PRODUCER GAS. 19 
 
 take up so much less oxygen, and therefore evolve so 
 much less heat. The oxygen is assumed to be combined 
 with hydrogen in the proportions required to form water, 
 so that the oxygen, being combined with one-eighth its 
 own weight of hydrogen, that amount will be unavailable 
 for combustion. If C H and be the percentage of these 
 elements, then 
 
 cp= 8080 C+ 29300 (g-iO). nCU| 
 
 C.P. = 1*544 C + 53000 (ff - j 0) in RTh-U . 
 
 assuming the products of combustion not to be condensed. 
 If they are, the higher values for H must be used. 
 
 The term (H % 0) is called the available hydrogen, 
 as it expresses the amount of hydrogen in the fuel which 
 is available for combustion. 
 
 Calorific Power of Gaseous Fuel. The calorific power of a 
 compound gas cannot be calculated from that of the 
 elements, because the formation of a compound is always 
 attended with the evolution of absorption of heat, and the 
 heat of combustion of the compound will be less or greater 
 than that of the elements just by this amount. 
 
 For example, Marsh gas CH 4 contains 75 per cent. C 
 and 25 per cent. H. Its heat of combustion calculated 
 from the elements and the water being condensed would 
 be 
 
 C = -75 x 8080 = 6060 
 H = -25 x 34180 = 8545 
 
 14605 
 
 The calorific power of Marsh gas as determined by 
 experiment is 13,062, so that the difference is 14,605 
 13,062 = 1,543. In this case the heat evolved 
 by the combustion of the gas is less than that which 
 would be evolved by the combustion of the elements 
 by 1,543 units, which is the amount of heat which would 
 be evolved by lib. of C combining with hydrogen to 
 form Marsh gas. 
 
 In the case of acetylene, which contains 92*3 per cent. 
 of and 7*7 per cent. H, the figures would be 
 C 8080 x -923 = 7457-8 
 H 34180 x -077 = 2631-8 
 
 10089-6 C.U. 
 
 or 
 
20 PRODUCER GAS. 
 
 The heat evolved by the combustion of lib. of the gas is 
 11,941 C.U., so that the gas in this case evolves more 
 heat on combustion than the free elements would do, 
 and the difference, 10,089 -- 11,941 - - 1,852, is the 
 heat absorbed by the union of lib. of carbon with hydrogen 
 to form acetylene. 
 
 It is obvious, therefore, that the calorific power of a 
 mixed gas must be calculated from the compound or 
 elementary gases of which it is a mixture, and not from 
 the elements which they contain considered as being free. 
 As the products of combustion will in practice be always 
 at temperatures above 100C., the amount of latent heat 
 held by the steam must be deducted from the experimental 
 figures in all cases where the gases contain hydrogen. 
 
 The following calorific powers will be needed : 
 
 Marsh gas, methane CH^. 
 C.P.= 13062 C.U.= 23512 B.Th.U. 
 
 Here for each pound of the gas burnt 2'251bs. of water will 
 be formed, so that the effective calorific power 
 C.P.= 13062 - (537 x 2-25) - 11854 C.U. 
 
 = 23512 - (966 x 2-25) = 21339 B.Th.U. ; 
 or, in round numbers for practical purposes, we may say 
 12,000 C.U. or 21,000 B.Th.U. 
 
 Ethylcnc (0 2 # 4 ). 
 
 C.P.= 11143 C.U. or 20057 B.Th.U. 
 
 As each pound of the gas produces l'281bs. of water, the 
 effective calorific power will be 
 
 C.P. = 11143 - (537 X 1-28) = 10456 C.U. 
 
 C.P.= 20057 - (966 x 1-28) = 18821 B.Th.U.; say, in 
 round numbers, 10400 C.U. or 18800 B.Th.U. 
 
 Acetylene. 
 
 C.P.= 11941 C.U. - 21493 B.Th.U. 
 
 As each pound of gas produces -691b. of water, the 
 effective C.P. will be 
 
 C.P = 11941 - (537 x 69) = 11571 C.U. 
 
 - 21493 - (966 x -69)=i20827 B.Th.U. ; say, in 
 round numbers, 11500 C.U. and 20800 B.Th.U. 
 
 From these figures it is easy to calculate the calorific 
 power of any gas. Take, for example, the gas already 
 considered : 
 
PRODUCER GAS. 21 
 
 Hydrogen -74 x 29,300 = 21,682 C.U. 
 
 Marsh gas 2-22x12,000 = 26,640 
 
 Ethylene -11 X 1 0,400 = 1,144 
 
 Carbon monoxide ... 23'27 x 2,400 55,848 
 Nitrogen ... ... 63*34 
 
 Carbon dioxide & oxygen 10*32 
 
 ForlOOlbs 105,314 
 
 C.P., i.e., heating power for lib. == 1,053'1 C.U. 
 As 100 cub. ft. of the gas weighs 7'24821bs., 1,000 cub. ft. 
 will weigh 72'4821bs., and the calorific power per 
 1,000 cub. ft. will be 
 
 76,333 C.U. 
 = 137,399 B.Th.U. 
 
 The calorific power of any other gas known composi- 
 tion can, of course, be calculated in the same way. 
 
 Calorific Intensity. The actual amount of heat evolved 
 by the combustion of any fuel is, as already explained, 
 fixed and definite, but the temperature that can be obtained 
 varies very much with varying conditions, such, for 
 instance, as rate of combustion. 
 
 The calorific intensity or pyrometric heating power is 
 the increment temperature that would be produced by the 
 combustion of lib. of the fuel. The temperature that can 
 be attained in practice can never be calculated, as the 
 conditions vary so much, but it is possible to calculate 
 what it would be under certain well-defined conditions, 
 and though the results obtained are not attainable in 
 
 o 
 
 practice, they are very valuable for comparison. The 
 assumption which lies at the base of all such calculations 
 is that all the heat is transferred to the products of 
 combustion, and that ^fcheref ore there is no loss of heat. 
 
 In order to show how the calorific intensity of fuels 
 may vary, and that the calorific intensity is not by any 
 means proportional to the calorific power, the cases of 
 carbon, hydrogen, and Marsh gas will be considered. 
 
 Carbon. One pound of carbon on burning forms 3f Ibs. 
 of carbon dioxide and evolves 8,080 units of heat, so that 
 if there were no loss of heat, and if the heat were all im- 
 parted to the products of combustion, the resulting 
 temperature would be 
 
 8080 
 
 3-67 x -2163 
 
 10178 C. 
 
22 PRODUCER GAS. 
 
 - 18321 F ' 
 
 2163 being the specific heat of carbon dioxide. 
 
 If, instead of being burnt in oxygen, the carbon were 
 burnt in air, the amount of heat would be the same, but 
 the oxygen used would be mixed with nitrogen, which 
 would remain with the carbon dioxide, and would have 
 to be heated to the same temperature. The 2f Ibs. of oxygen 
 required for the combustion of lib. carbon would be mixed 
 
 77 
 
 with 2-67 x ^ == 8'9 parts of nitrogen in the air. So that 
 Zo 
 
 the C.I. would be 
 
 PT 8080 _ 
 
 (3-67 X -2163) + (8-9 x -2438) 
 
 and if there be an excess of air, then the excess of air x 
 its specific heat must also be added to the denominator, 
 and would thus further reduce the temperature. 
 
 Hydrogen. In the case of hydrogen the heat evolution 
 is, assuming the temperature of the gases to be above 
 100C. 29,300 units, and it yields nine parts of water 
 which as steam has a specific heat of -4805 ; so that 
 _ 29300 
 " 9 x -4805 
 and if the combustion be in air, as eight parts of oxygen 
 
 will be mixed with 8 x -^- = = 26*8 parts of nitrogen, 
 
 29300 
 
 (9 x -4805) + (26-8 x -2438) 
 Therefore, whilst the actual amount of heat evolved by 
 the combustion of carbon and hydrogen is in the ratio of 
 1 : 3 -62, the temperature attainable by the combustion 
 of hydrogen and carbon in oxygfcn is in the ratio of 
 1 : -68. 
 
 The calculation of the calorific intensity of some 
 other gases, though not of much practical importance, is 
 instructive. 
 
 Carbon Monoxide. 
 
 . 1 
 
 1-57 x -2163 
 
 or if burnt in air 
 
 2400 
 
 (1-57 x -2163) + (1-91 x -2438) 
 
 j.5 - 7067, 
 
 = 2980 
 
PRODUCER GAS. 23 
 
 Marsh Gas. The calorific power is 12,000. In oxygen 
 
 rT = 12000 
 
 (2-75 x -2163) + (2-25 x -4805) 
 And in air 
 
 r = 12000 
 
 ' ~(2-75 x -2163)-i-(2-25 x -4s05) + (13-4 x -2438) 
 
 -2427. 
 
 In order to calculate the calorific power of any mixed gas 
 it is necessary to know the nature and weight of the 
 products of combustion, the specific heat, and the amount 
 of oxygen consumed. 
 
 To take again the gas dealt with in the previous 
 examples, which contained 
 
 Hydrogen ... ... ... ... '74 
 
 Marsh gas 2*22 
 
 Ethylene '11 
 
 Carbon monoxide ... ... ... 23*27 
 
 Oxygen ... ... ... ... 1*85 
 
 Carbon dioxide ... ... ... 8*47 
 
 Nitrogen 63*34 
 
 The calorific intensity in oxygen will be 
 
 p -r _ ( -0074 x 29300) + ( -Q222 x 12000) + ( -001 x 10400) + ( "2327 x 2400) 
 ~ (-5146x -2163) + (-1177 x -4805) + ( -6334 x '2488) 
 
 - 3264 
 Or in air 
 
 p T ( -0074 x 29300) + ( -0222 x 12000) + ( "001 x 10400) + ( '2327 x 2400) 
 
 (5146 x -2163) + (-1177x -4805) + (1 -5238 x -2438) 
 
 = 1950. 
 
 Temperature of Combustion. In order that combustion 
 may take place a certain temperature is necessary, and if 
 the gas be very much diluted, or if a very large excess of 
 air be used, it may happen that the temperature produced 
 by combustion is insufficient to keep the gas alight. This 
 is not uncommon with poor gas, such as blast-furnace 
 gas, and in such cases it is necessary to keep a fire of 
 solid fuel burning on the grate, or to keep up the tempera- 
 ture in some other way. 
 
 Heat Carried Away by the Products of Combustion. It is 
 always essential, except in certain cases where a forced 
 draught is used, to allow the products of combustion to 
 leave the furnace at a high temperature, in order that a 
 good draught may be produced, and thus a large amount 
 of heat may be carried away. If the temperature of the 
 
24 PRODUCER GAS. 
 
 gas be known, it is easy to calculate the amount of heat 
 carried. Thus in the gas which has already been considered, 
 for each pound of gas the products of combustion are : 
 
 Carbon dioxide... -51461bs. x "2163 = -1113 C.U. 
 
 Water -11771bs. x '4805 = -0565 
 
 Nitrogen -63341bs.| v . 94 oo _. .07-, * 
 
 89041bs.j X 24< "__ " 
 
 5393 
 
 If the weight of each gas be multiplied by its specific 
 heat, the sum will be the amount of heat carried away by 
 each pound of fuel consumed in this case '5393 units of 
 heat for each 1C. of temperature of the gas above the 
 temperature of the air ; or if the gases were at 200C. 
 (the air being at 0), a very moderate temperature, the 
 loss would be 107*8 units, or 10*8 per cent, of the 
 heating power of the fuel. In practice the amount of 
 heat carried away will be much larger, as there will 
 always be considerable excess of air 
 
 Heating by Contact and by Radiation. The way in which 
 the heat is to be applied to a certain extent modifies 
 the value of the gas. A non-luminous flame, such 
 as that of hydrogen or carbon monoxide, may have 
 a very high temperature and be very efficient for 
 heating where the flame can come in contact with 
 the surface being heated, but it radiates heat very feebly, 
 and therefore is not efficient where heating by radiation 
 is required. On the other hand, a luminous flame loaded 
 with hot carbon is not very efficient where contact heating 
 is required, and deposits soot very readily, but it is 
 excellent for heating by radiation. As heating by radia- 
 tion is far more extensively used than heating by contact, 
 a gas which burns with a luminous flame is in general 
 better than one the flame of which is non-luminous. 
 
CHAPTEK III. 
 
 NATURAL GAS. COAL GAS. OIL GAS. ACETYLENE. 
 
 Natural Gas. This gas is of little importance in this country. 
 A brief mention of it may, however, be of interest, in order 
 that it may be compared with other gases used for fuel. 
 The following may be taken as an average analysis by 
 volume : 
 
 Carbon dioxide ......... '6 
 
 Carbon monoxide ...... '6 
 
 Oxygen .................. -8 - 
 
 Ethylene .................. 1-0 Pecentage of 
 
 Ethane (C 2 H.) ......... 5-0 
 
 Methane (C H 4 ) ......... 67-0 
 
 Hydrogen ............... 22'0 
 
 Nitrogen .................. 3-0 
 
 100-0 
 
 It will be seen, therefore, that the gas is composed 
 almost entirely of combustible gases, there being only 4'4 
 per cent, of diluents, and its calorific power will there- 
 fore be very high. Owing to the large quantity of 
 ethylene, it burns with a very luminous flame. The 
 percentage composition by weight will be : 
 
 Carbon dioxide... -6 x '1227 = -0736 ... 1-82 
 
 Carbon monoxide '6 X '0781 - -0469 ... 1-16 
 
 Oxygen -8 x -0893 = -0714 ... 177 
 
 Ethylene 1-0 X -0784 = -0784 ... 1-94 
 
 Ethane 5'0 X '0837 = -4185 ... 10-35 
 
 Methane 67'0 x "0447 = 2-9949 ... 74-09 
 
 Hydrogen 22-0 x -0056 = -1232 ... 3'05 
 
 Nitrogen .. 3-0 x -0784 = -2352 ... 5-82 
 
 4-0421 100-00 
 
 Coal Gas. Coal gas, as is well known, is prepared by 
 the destructive distillation of coal. The gases are not 
 present in the coal, but are produced by destructive action 
 of the heat, whence the name destructive distillation. 
 
26 
 
 COAL GAS. 
 
 The gas consists almost entirely of combustible gases r 
 and burns with a highly luminous, often smoky, flame. 
 The composition of the gas varies considerably according 
 to the coal used and conditions of distillation, but the 
 lighting power varies much more than the heating power r 
 probably because the dense hydrocarbons, which are the 
 principal illuminating constituents, are somewhat unstable, 
 and tend to break up at high temperatures. The 
 principal illuminating constituent is ethylene, but this is 
 .always associated with larger or smaller quantities of its 
 higher homologues of the olefine, or C n H 2n series, and 
 hydrocarbons of lower series, such as the acetylene 
 C n H 2n _ 2 series. The distillation also produces large 
 quantities of liquid hydrocarbons which are removed by 
 condensation and washing, and which are known collectively 
 as coal tar, and also gaseous and liquid compounds 
 containing sulphur, viz., hydrogen sulphide H 2 S and carbon 
 disulphide CS 2 , which are removed when the gas is to be 
 used for illuminating purposes. Some of the nitrogen 
 present in the coal is given off as ammonia which is 
 dissolved in the water used for washing the gas, and 
 is afterwards recovered and converted into ammonium 
 sulphate. There are two varieties of coal gas, that made 
 from ordinary bituminous gas coal and that made from 
 cannel coal, the latter containing a much larger percentage 
 of the olefines, and therefore having much greater 
 illuminating power. 
 
 The following analyses may be taken as illustrating 
 the composition of coal gas by volume. 
 
 
 (i) 
 
 (2) 
 
 (3) 
 
 Hydrogen 
 
 51-80 
 
 48*32 
 
 36-10 
 
 Carbon monoxide 
 Marsh gas 
 
 9-10 
 31-80 
 
 4-63 
 39-55 
 
 6-80 
 37-80 
 
 Olefines .... 
 
 5-20 
 
 5-18 
 
 16-40 
 
 Nitrogen 
 
 2-10 
 
 2-32 
 
 2-90 
 
 
 
 
 
 
 100-00 
 
 100-00 
 
 100-00 
 
 (1) and (2) London gas, (3) cannel gas. 
 
 It will be seen that the gas consists almost entirely of 
 combustibles, there being only about 2 or 3 per cent, of 
 
COAL GAS. 27 
 
 diluents, and that the great bulk of it is gases that burn 
 with a non-luminous flame, though by the high temperature 
 they produce they assist in making luminous the carbon 
 separated from the ethylene. 
 
 Taking an average analysis as : * 
 
 By Weight, 
 
 Hydrogen ... 48 x '0050 = -2688 = 8'59 % 
 
 Carbon monoxide 8 x '0781 = -6248 = 19*96 
 
 Methane ... 36 x -0447 = = 1-6092 == 51-41,, 
 
 Ethylene ... 3-8 x -0784 = -2979 = 9-52,, 
 
 Nitrogen ... .4-2 x -0784 -3293 = 10-52 
 
 3-1300 100-00 
 
 1,000 cub. ft. of the gas would weigh 31'311bs. 
 The calorific power can be easily calculated : 
 
 Hydrogen -0859 x 29300 = 2516-9 
 
 Carbon monoxide -1996 x 2400== 479'0 
 
 Methane -5141 x 12000 = 6169'2 
 
 Ethylene -0952 x 10400 = 990-1 
 
 Nitrogen -1052 
 
 10155-2 
 
 and as 1,000 cub. ft. weigh 31'31bs., theheat evolved by the 
 combustion of 1,000 cub. ft. will be 317858 C.U., 572144 
 B.Th.U. Such a gas will require a very large amount 
 of oxygen for its combustion. 
 
 Hydrogen 48 X -5 = 24 
 
 Carbon monoxide 8 x -5 = 4 
 Methane 36 x 2-72 
 
 Ethylene 3-8 x 3 = 11-4 
 
 Nitrogen 4-2 
 
 111-4 
 
 100 volumes of the gas will thus require 111-4 volumes 
 of oxygen or 530-5 volumes of air. The weight of the 
 products of combustion will also be very large. 
 The advantages of coal gas as a fuel are : 
 (1) Owing to its high calorific power, a large amount 
 of heat can be obtained from a small quantity of gas, and 
 therefore for many small operations where cost of the fuel 
 is of small importance it is of great value, and is very 
 largely used. 
 
 * J. S. C. I., 1888, p. 20. 
 
28 COAL GAS. 
 
 (2) It burns with a very luminous flame, and thus is 
 well suited for heating by radiation where the flame is 
 not brought in contact with any cold surface. 
 
 Against these advantages are to be set two dis- 
 
 (1) The cost is very great. Assuming gas to be 
 supplied at 2s. 6d. per 1,000 cub. ft., the cost per 1,000 
 
 ., . 30000 
 
 units of heat will be in pence Q ^^ = '094. 
 
 ol i oOo 
 
 Supposing a coal with a heating power of 8,000 to be 
 obtainable at 15s. a ton, the cost per 1,000 units of heat 
 obtained from it would be 
 
 15 X 12 180 X 1000 
 
 2240 x 8000 : 17920000 
 
 In some cases the convenience of the gas is so great 
 that even with this great difference in cost its use is advan- 
 tageous, but it is quite obvious that such cases will not be 
 very numerous. 
 
 (2) The gas has a great tendency to smoke and to 
 deposit soot, a defect common to all highly luminous 
 gases, hence burners must be so arranged that there is a 
 large surface exposed to the air. This prevents the use of 
 large flames, and therefore renders the gas unsuitable for 
 use on a large scale. When the burning gas comes in 
 contact with a cold surface, combustion is always incom- 
 plete, soot is deposited, and thus the efficient heating 
 power is very much reduced. The soot is a very bad 
 conductor, and is extremely troublesome. 
 
 In order to avoid the difficulty, when coal gas is used 
 as a fuel it is usually diluted with air, as in the Bunsen 
 burner, till its richness is reduced and the flame becomes 
 non -luminous. It will be seen, however, that this is to 
 sacrifice the chief advantages of coal gas and to reduce it 
 to the rank of the cheaper non-luminous producer gas. 
 Coal gas is largely used for domestic heating in this way, 
 not because it is the cheapest or best gas for the purpose, 
 but because it is the only one which is available. 
 
 The high cost of coal gas is due to several reasons : 
 
 (1) When the coal is distilled only a small proportion 
 
 of the fuel, rarely 30 per cent., is converted into gas, the 
 
 greater part being left as a residue or coke. The coke is 
 
OIL GAS. 
 
 29 
 
 of course a by-product, and has a relatively small value 
 because the coals which are best for gas making usually 
 yield an inferior coke, which is often very high in ash. 
 
 (2) The coals are selected because of the high 
 illuminating power of the gas they yield, and are therefore 
 relatively costly. 
 
 (3) A considerable quantity of fuel is used in the 
 distillation. 
 
 (4) As the gas is to be used mainly for illuminating 
 purposes, and therefore will be burnt in rooms often 
 with little ventilation, and often containing articles that 
 might be damaged by sulphur oxides, the gas must be 
 thoroughly freed from sulphur, which is a somewhat 
 costly process. 
 
 Oil Gas. This gas is made by the destructive distillation 
 of mineral oils by very rapid heating to a high tempera- 
 ture. The composition of the gas varies considerably, 
 the following analysis will serve as an illustration of its 
 composition : 
 
 
 By Volume. 
 
 By Weight. 
 
 Hydrogen 
 
 31 61 
 
 4-43 
 
 Carbon monoxide 
 Luminous hydrocarbons^ . . 
 Marsh gas 
 
 14 
 16-29 
 46-17 
 
 27 
 31-96 
 51-77 
 
 Nitrogen 
 
 5-06 
 
 9-93 
 
 Oxygen 
 
 73 
 
 1-64 
 
 
 
 
 It will be seen that the gas resembles coal gas in some 
 respects. Owing to the high percentage of ethylene, it 
 burns with a very luminous flame, and shows a very great 
 tendency to produce smoke and deposit soot. It requires a 
 very large quantity of air for its combustion, and is quite 
 unsuited for use as a fuel gas under ordinary conditions, 
 even if its cost were not prohibitive. 
 
 Assuming the luminous hydrocarbons to be ethylene, 
 the calorific power of the gas and the amount of oxygen 
 required for combustion would be : 
 
 J Chiefly Ethylene. 
 
80 
 
 ACETYLENE. 
 
 
 
 CP 
 
 O per 100 cub. ft. 
 
 Hydrogen 
 
 0443 
 
 1298- 
 
 15-80 
 
 Carbon monoxide . . 
 Ethylene 
 
 0027 
 3196 
 
 6-5 
 3323-8 
 
 07 
 
 48-87 
 
 Marsh gas . ... 
 
 5177 
 
 6212-4 
 
 92-34 
 
 Nitrogen 
 
 0993 
 
 
 
 Oxygen . . 
 
 0164 
 
 
 
 
 
 
 
 Less oxygen present.. 
 
 
 
 10840-7 
 
 157-08 
 73 
 
 
 1-0000 
 
 
 156-35 cf or 
 air 744-5 cf. 
 
 According to Mills & Rowan, the amount of gas pro- 
 duced by the process in which the oil is broken up by 
 being allowed to fall into retorts filled with red-hot bricks 
 or similar processes is about 150 cub. ft. per gallon of oil. 
 Assuming the oil to have a specific gravity of -9200, one 
 gallon of the oil would weigh about 9*21bs. and the yield 
 would be 36,522 cub. ft. per ton. 
 
 Acetylene. Closely allied to these highly luminous gases, 
 though made by quite a different process, is acetylene. 
 When a mixture of lime and carbon is heated to a very 
 high temperature by the electric arc, decomposition takes 
 place, carbon monoxide is evolved, and a carbide of 
 calcium is left. 
 
 Ca O + 3C = = Ca C a + C O. 
 When this carbide is treated with water acetylene is evolved, 
 
 Ca C 2 + 2 H 2 O = = Ca O, H 2 O + C 2 H 2 
 Acetylene burns with a more luminous flame than any 
 other hydrocarbon. The gas is, however, quite unsuited 
 for use as fuel. It is very unstable, its decomposition 
 evolving a considerable amount of heat, and at high 
 temperatures it may even decompose with explosion. 
 There is a great tendency to the separation of carbon 
 during combustion, and consequent production of smoke, 
 and when used for lighting it requires the use of very 
 small burners and a copious supply of air. 
 
 The following series of analyses of acetylene made 
 from calcium carbide are given by Prof. Lewes in his 
 Cantor lectures on acetylene : 
 
 Journal of the Society of Arts, vol. 47 (1899), p. 137. 
 
ACETYLENE. 
 
 31 
 
 
 American 
 Carbide. 
 
 German 
 Carbide. 
 
 Swiss 
 Carbide. 
 
 Phosphoretted hydrogen ... 
 Sulphuretted hydrogen 
 Ammonia 
 
 0-05 
 
 0-08 
 0-08 
 
 0-03 
 0-07 
 
 C-07 
 
 0-03 
 
 o-io 
 
 0-11 
 
 Hvdroffen 
 
 0-09 
 
 0-07 
 
 0-16 
 
 Nitrogen 
 
 0-42 
 
 0-20 
 
 0-34 
 
 Oxycren . 
 
 0-87 
 
 0-55 
 
 0-63 
 
 Acetylene 
 
 98-41 
 
 99-01 
 
 98-63 
 
 
 
 
 
 - 
 
 100-00 
 
 100-00 
 
 100-00 
 
CHAPTER IV. 
 
 SIMPLE PRODUCER GAS. STEAM ENRICHED PRODUCER 
 GAS. COAL ENRICHED PRODUCER GAS. CARBON 
 DIOXIDE IN PRODUCER GAS. EFFICIENCY OF A 
 GAS PRODUCER. Loss OF HEAT IN GAS PRODUCER. 
 
 IN all gases produced by destructive distillation a con- 
 siderable portion of the fuel used is left as a solid non-volatile 
 residue, and unless this can be economically used the gas 
 must be very costly. In order to prepare a gas for use 
 as fuel at cheap rate the whole of the fuel must be 
 gasified, and this is done in the manufacture of producer 
 gas. When carbon in any form, for example, coke or 
 charcoal, is burnt in a limited supply of air at a high 
 temperature the product of combustion is carbon monoxide, 
 and this is combustible. If, therefore, the fuel be thus 
 burnt all the carbon is converted into combustible 
 carbon monoxide, and no residue is left except the 
 non-combustible ash. 
 
 In order that theory of the manufacture of producer 
 gas may be clearly understood it will be best to 
 describe some simple form of gas producer, and consider 
 what changes take place in it, and then to consider the 
 commercial forms of producer in use to-day. For this 
 purpose the producer designed by Bischof and once 
 used in the Hartz may be taken. It is shown in section 
 in Fig. 1. 
 
 It will be seen from the sketch that it is little more 
 than a deep fireplace indeed, this is the character of all 
 simple producers. The fuel is supplied at the top, the 
 ashes are poked out through the bars at the bottom, and 
 the gases are drawn off near the top. 
 
 Simple Producer Gas. In a gas producer almost any fuel 
 may be used, but at the outset it will be best to consider 
 the case of a more or less pure carbon such as coke or 
 charcoal, as the reactions which take place are simpler in 
 this case than in any other Coke is now rarely used in 
 practice except when the gas is to be used for gas 
 
PRODUCER GAS. 
 
 33 
 
 FIG. 1. BISCHOF PRODUCER. 
 
 engines, and therefore the absence of tarry matter is 
 essential. Suppose the producer figured above to be full 
 of coke or charcoal which is burning. As the air passes 
 in between the bars combustion will take place and 
 carbon dioxide will be formed, which will, however, if the 
 temperature be high enough and the quantity of coke 
 large enough, be at once reduced to carbon monoxide, so 
 that the net result will be the combustion of the carbon 
 to carbon monoxide (C + O = CO), in which form it leaves 
 the producer. Such a gas may be called simple producer 
 gas, to distinguish it from the steam and hydrocarbon 
 enriched gases which are usually used. 
 
 The air , consists of oxygen and nitrogen mixed in 
 approximately the following proportions : 
 
 Oxygen 
 Nitrogen 
 
 O 
 
 By Volume. 
 
 21 
 
 79 
 
 By Weight. 
 
 23 
 
 77 
 
 When carbon burns to form carbon monoxide, the carbon 
 monoxide produced occupies twice the volume of the 
 
34 PRODUCER GAS. 
 
 oxygen which it contains, therefore 100 volumes of air 
 will yield 79 volumes of nitrogen, passing through 
 unchanged, and 42 volumes of carbon monoxide, so that 
 the composition of the gas will be 
 
 Carbon monoxide ... 42 = 34-7 per cent. 
 
 Nitrogen 79 = 65 -3 
 
 121 100-0 
 
 provided that there be no carbon dioxide left unreduced. 
 As in this case the two gases of which the gas is composed 
 have almost the same specific gravity, the percentage 
 composition by weight will be the same as that by volume, 
 so that the composition by weight will be 
 
 Carbon monoxide... ... ... ... 34*7 
 
 Nitrogen 65-3 
 
 HXH) 
 
 1,000 cub. ft. of the gas will weigh about 781bs., and 
 one ton of carbon would give about 190,000 cub. ft. of 
 gas. Assuming the coke used to contain 90 per cent, of 
 carbon, one ton of coke would yield about 171,000 cub. ft. 
 of gas. 
 
 The heating power of the gas will necessarily be 
 small, as 65 '3 per cent, of it is not combustible, and the 
 remaining portion, which is combustible, has a low 
 calorific power. 
 
 The calorific power of the gas will be '347 X 2,400 = 
 832-8 CU = 1,499 B.Th.U., and 1,000 cub. ft. of the gas 
 weighing about 781bs., evolve 64,958 C.U., or 116,925 
 B.Th.U. 
 
 One pound of carbon will have combined with 1 - 331bs. 
 of oxygen and produced 2 - 331bs. of carbon monoxide, 
 which, mixed with the nitrogen, will give 6'7llbs. of 
 simple producer gas. 
 
 C.U. B.Th.U. 
 
 lib. of carbon burning to carbon dioxide 
 
 would give 8,080 14,500 
 
 6'711bs. of simple producer gas burning 
 
 to carbon dioxide will give ... ... 5,588 10,058 
 
 Difference 2,492 4,442 
 
 This difference is just about 31 per cent, of the total 
 heat which the 'solid fuel could evolve on combustion, and 
 
PRODUCER GAS. 35 
 
 therefore the conversion of the fuel into gas has been 
 attended with a loss of 31 per cent, of the heating power 
 of the fuel. 
 
 This loss of heat is not, however, an absorption. It 
 is not of the character of latent heat, or heat absorbed in 
 doing work, as when water is boiled into steam, which 
 heat can be recovered by reversing the change by 
 condensing the steam back into water, but it is heat 
 evolved, but evolved in the producer, where it is only 
 to a small extent useful, instead of in the furnace, where 
 it is wanted. What becomes of this heat will be fully 
 considered later. 
 
 Simple producer gas can be used in a few cases, but 
 its low heating power and the large loss of heat in its 
 production are great disadvantages. 
 
 The gas can, however, be enriched by the use of coal 
 instead of coke in cases where the products of distillation 
 of the coal are not objectionable, and it can also be 
 enriched and at the same time the expenditure of heat in 
 its production can be reduced by using steam in conjunction 
 with the air. 
 
 Steam Enriched Gas. When steam is blown over red-hot 
 coke it is decomposed thus : C + H 2 U = CO + 2H, so 
 that the steam yields its own volume of carbon monoxide 
 and its own volume of hydrogen. 
 
 Each pound of carbon burnt by steam yields the 
 same volume of carbon monoxide which it would do if 
 burnt in air, but this, instead of being mixed with about 
 twice its own volume of nitrogen, which is useless, is 
 mixed with its own volume of hydrogen, which is 
 combustible, and has a high calorific power. Thus the 
 gas is enriched by the addition of hydrogen and at the 
 same time by a reduction in the percentage of nitrogen. 
 
 The decomposition of steam by carbon is made up of 
 two parts, each of which will have its own thermal value ; 
 first, the formation of a molecule of carbon monoxide, and 
 second, the decomposition of a molecule of water. The 
 first of these will evolve and the second will absorb heat. 
 
 It will be seen that for each pound of hydrogen 
 liberated Gibs, of carbon will be consumed, and will 
 produce 141bs. of carbon monoxide. The thermal changes 
 
36 PRODUCER GAS. 
 
 can be thus expressed, taking the figures in round 
 numbers : 
 
 C.U. B.Th.U. 
 
 Heat absorbed in separating lib. 
 
 of hydrogen from the oxygen 
 
 with which it was combined in 
 
 the water 29,000 52,200 
 
 Heat evolved in the combustion of 
 
 61bs. of carbon to carbon 
 
 monoxide 14,400+ 25,920 + 
 
 Heat absorbed by the reaction for 
 
 each 61bs. of carbon oxidised... 14,600- 26,280 
 Heat absorbed for each pound of 
 
 carbon oxidised 2,433- 4,380 
 
 It is obvious that the amount of steam which can be 
 used is limited, for if steam alone were used, unless 
 heat were supplied from some external source, the fuel 
 would soon be cooled below the temperature at which the 
 decomposition could take place, and the reaction would 
 cease. 
 
 If air and steam be blown in together the combustion 
 of the carbon by the air will supply the necessary heat to 
 keep up the combustion, and as the combustion of carbon 
 by air takes place at a much lower temperature than the 
 decomposition of steam, if excess of steam be used it will 
 not stop the combustion altogether, but by lowering the 
 temperature will cause the production of a large quantity 
 of carbon dioxide, and at the same time the excess of 
 steam will pass through undecomposed, and thus will 
 remain mixed with the gas. 
 
 It is obvious that if air and steam be supplied 
 together and the steam is to be decomposed the quantity 
 of air must be sufficient to keep up the temperature of 
 the fuel to the point at which decomposition of the 
 steam can take place. Since each pound of carbon 
 burnt by steam absorbs 2,433 C.U., and each pound burnt 
 by air evolves 2,400 C.U., it is clear that if there were 
 absolutely no loss of heat the quantity of carbon burnt 
 by air must be about the same as that burnt by steam. 
 In practice loss of heat cannot be avoided, and to com- 
 pensate for this a much larger quantity of carbon must 
 be burnt by air. 
 
PRODUCER GAS. 37 
 
 In order to see the effect of the use of steam a case 
 may be assumed in which for every 51bs. of carbon 
 consumed 41bs. is burnt by air and lib. by steam, 
 proportions not very far removed from those in actual 
 practice. 
 
 For simplicity in expressing the results 12 grammes 
 will be taken as the unit. Twelve grammes of carbon 
 burnt by air gives 22 '4 litres of carbon monoxide, whch 
 will be mixed with 42*1 litres of nitrogen, and 12 grammes 
 of carbon burnt by steam will give 22-4 litres of carbon 
 monoxide and 22*4 litres of hydrogen, so that 
 48 grammes of carbon burnt by air will give 
 
 Nitrogen = 42-1 x 4 = 168-4 
 
 Carbon monoxide = 22-4 x 4 = 89-6J 
 
 12 grammes of carbon burnt by steam will give 
 
 Carbon monoxide ... ... ... ... 22 -4 J 
 
 Hydrogen ... ... ... ... ... 22 -4 
 
 And the composition of the resulting gas will be (by 
 volume) 
 
 Carbon monoxide... 37'Opercent.) 44-4 per cent. 
 Hydrogen... ... 7-4 j combustible. 
 
 Nitrogen ... ... 55 '6 ,, 
 
 The gas is therefore much richer in combustibles than 
 simple producer gas. 
 
 The composition of the gas by weight will be 
 Carbon monoxide ... ... ... 39*73 
 
 Hydrogen ... ... -57 
 
 Nitrogen 59*70 
 
 100-00 
 
 Owing to its extreme lightness the percentage of 
 hydrogen by weight is very small. 
 
 The calorific power of the gas will be 
 
 3973 x 2400 = 953-5 C.U. 
 
 0057x29300 ... = 167-0 C.U. 
 
 1120-5 C.U. 
 
 as against 832, an increase of 287 C.U., or about 35 
 per cent. 
 
 In B.Th.U the figures will be 
 
 3973 x 4320 = 1716-3 
 0057 x 53000 = 302-1 
 
 2018-4 B.Th.U. 
 
38 PRODUCER GAS. 
 
 One ton of carbon thus burnt will yield about 181,000 
 cub. ft. of gas, or, assuming the coke to contain as before 
 90 per cent, of carbon, one ton will yield about 163,000 
 cub. ft. 
 
 One thousand cubic feet of the gas will weigh about 
 72-91bs., and will evolve on combustion about 81,684 C.U.,, 
 or 147,141 B.Th.U. 
 
 One pound of the gas will contain -17051b. of carbon. 
 This if completely burnt to carbon dioxide would give 
 
 17 x 8080 =1374 C.U. - 2478 B.Th.U. 
 One pound of the gas gives 
 
 1120-5 C.U. = 2018-4 B.Th.U. 
 
 Loss 253-5 454-6 
 
 Or only about 20 per cent, of that which the solid fuel 
 would give. 
 
 Thus by the use of steam in the proportion assumed 
 the gas has been enriched by about 35 per cent., and the 
 loss of heat in its production has been reduced from 31 
 to 20 per cent., a saving of about 11 per cent. 
 
 The action of the steam can be easily explained. 
 Owing to the absorption of heat by the decomposition of 
 the steam less heat is evolved in the producer, and an 
 additional amount equal to that thus saved can be 
 evolved in the furnace. The steam thus acts as a carrier 
 of heat, and, whilst it cannot increase the total amount of 
 heat evolved, it alters its distribution. The larger the 
 proportion of steam that can be used the better, but 
 for the reasons explained above excess must be carefully 
 guarded against. 
 
 Coal Enriched Gas. '1 he gas may be further enriched 
 by the use of coal instead of coke. The coal is then 
 distilled at the top of the producer by the heat of the 
 ascending gas, the otherwise waste heat being thus 
 utilised, and the producer gas is enriched by the addition 
 of the coal gas produced by the distillation. 
 
 Assume the producer to be charged with a coal 
 yielding, say, 65 per -cent, of fixed carbon and 5 per cent, 
 of ash, and giving, say, 10,000 cub. ft. of gas per ton, the 
 gas containing by volume, say, 50 per cent, of hydrogen, 
 40 per cent of hydrocarbons, and 10 per cent, of carbon 
 monoxide. It will not be difficult to see the nature of 
 the gas which will be produced. It may be assumed that 
 
PRODUCER GAS. 39 
 
 steam is used as before. As there is only 65 per cent, of 
 fixed carbon in the fuel, it will yield 181,000 x -65 = 
 117,650 cub. ft. of producer gas per ton of coal, which will 
 have the same composition as that already given, and, in 
 addition, there will be 10,000 cub. ft. of coal gas having 
 the composition given above, so that the 128,000ft. of gas 
 will contain 
 
 r Hydrogen ... 5,000 
 
 From the coal gas . .. -j Hydrocarbons ... 4,000 
 { Carbon monoxide ... 1,000 
 
 r Hydrogen 8,706 
 
 From the producer gas -j Carbon monoxide... 43,530 
 [Nitrogen ... ... 65,414 
 
 This will give the composition by volume 
 
 Hydrogen 10-8 
 
 Hydrocarbons ... ... ... 3'1 
 
 Carbon monoxide ... ... 34-9 
 
 Nitrogen ... ... ... 51 -2 
 
 100-0 
 Assuming the hydrocarbons to be all Marsh gas the 
 
 percentage composition by weight will be 
 
 Hydrogen -87 
 
 Hydrocarbons (Marsh gas) ... ... 1-98 
 
 Carbon monoxide ... ... ... 39 '38 
 
 Nitrogen ... 5776 
 
 The calorific power will be, in Centigrade units 
 
 Hydrogen -0087 X 29300 = 254-9 
 
 Marsh gas -0199 X 12000 = 238-9 
 
 Carbon monoxide . -3938 X 2400 = 945 -1 
 
 1438-8 
 In British thermal units 
 
 Hydrogen -0087 x 53000 = 461-1 
 
 Marsh gas -0199x21000= 417*9 
 
 Carbon monoxide.., -3938 X 4320 = 1701-2 
 
 2580-2 
 
 1,000 cub. ft. of the gas will weigh about 69'51bs. and will 
 evolve on combustion 99,996 C.U., or 179,323 B.Th.U. 
 
 The following analyses of producer gas will serve to 
 show how the composition of gas, in practice, agrees with 
 
40 
 
 PRODUCER GAS. 
 
 the examples worked above. When coal is used, calcula- 
 tions as to the composition of the gas can only be 
 rough approximations owing to variations in the quantity 
 and composition of the coal gas, with the quality of the 
 coal used. 
 
 EXAMPLES OF PRODUCER GAS. 
 
 
 (i) 
 
 (2) 
 
 (3) 
 
 (4) 
 
 (5) 
 
 Hydrogen 
 Hydrocarbons ... 
 Carbon monoxide 
 
 8-60 
 2-40 
 2440 
 
 12-13 
 2-00 
 26-40 
 
 10-90 
 1-28 
 27-00 
 
 19-43 
 2-66 
 16-15 
 
 12-60 
 3-50 
 20-40 
 
 Carbon dioxide 
 
 5-20 
 
 9-16 
 
 4-50 
 
 11-53 
 
 5-50 
 
 Nitrogen 
 Per cent, combustibles .. 
 
 59-40 
 35-40 
 
 50-31 
 40-53 
 
 5632 
 39-18 
 
 50-23 
 38-24 
 
 58-00 
 36-50 
 
 Carbon Dioxide in Producer Gas. It will be noticed 
 that all the above analyses show in addition to the 
 constituents already considered the presence of carbon 
 dioxide. This gas is very objectionable, and if 
 present in larger quantities than 4 or 5 per cent, shows 
 either badly designed producers or careless working, very 
 frequently by use of excess of steam, and therefore undue 
 cooling. The effect of the carbon dioxide is threefold. 
 
 (1) It represents its own volume of carbon monoxide 
 burnt in the producer, and therefore so much the less 
 combustibles and the more non-combustibles present in the 
 
 (2) Since it contains twice as much oxygen as carbon 
 monoxide it adds an additional amount of nitrogen, which 
 is useless, to the gas. 
 
 (3) It causes the useless evolution of a large additional 
 amount of heat in the producer. 
 
 The extent to which carbon dioxide deteriorates the 
 value of the gas can be seen by considering the case of 
 simple producer gas. Suppose that in such a gas instead 
 of all the carbon being burnt to carbon monoxide one-fifth 
 of it leaves the producer as carbon dioxide. Since carbon 
 dioxide occupies the same volume as carbon monoxide 
 containing the same amount of carbon, 60 grammes of 
 carbon would give 
 
PRODUCER GAS. 41 
 
 4 x 12 grammes of C. burnt to carbon- 
 monoxide 4x22-4== 89-61itres 
 
 1 x 12 grammes of C. burnt to carbon dioxide 
 
 1x22-4- 22-4 
 
 Nitrogen from air yielding 67 -2 litres of 
 
 oxygen required for the combustion ...252 -8 ,, 
 
 364-8 
 
 The percentage composition by volume will be : 
 Carbon monoxide ... ... ... 24-6 
 
 Carbon dioxide ... ... ... ... 6*1 
 
 Nitrogen 69-3 
 
 By weight the composition would be : 
 
 Carbon monoxide ... 23*7 
 
 Carbon dioxide ... ... 9 '3 
 
 Nitrogen 67-0 
 
 100-0 
 The calorific power would be : 
 
 In C. units -237x2400=568-8 
 
 In B.Th. units -237 X 4320 = 1024 
 
 The gas contains 12-69 per cent, of carbon, or in lib. 
 1269lb., and this burnt completely would yield 
 1269 x 8080 = 1025-3 C.U. 
 1269 X 14500= 1840-0 B.Th.U. 
 The loss of heat in the producer, therefore, 
 1025 568 = 457 C.U. 
 1840 1024 = 816 B.Th.U. 
 
 The presence of 6'1 per cent, of carbon dioxide by 
 volume^-an amount well within that often found in 
 practice in the gas represents a loss of one-fifth of the 
 carbon consumed, a reduction of the calorific power of 
 gas by about 264 C.U., or about 32 per cent., and 
 increase of loss of heat in the producer from 31 
 to 46 per cent. This obviously means a very large 
 waste of fuel. 
 
 The presence of carbon dioxide in the gas is always 
 due to one of three causes : 
 
 (1) Too low a temperature in the producer, generally 
 produced by the use of too large a quantity of steam. 
 
42 EFFICIENCY OF GAS PRODUCERS. 
 
 (2) The layer of hot fuel not being sufficiently thick to 
 allow of the complete decomposition of the carbon dioxide 
 produced. 
 
 (3) The leakage of air into the producer above the 
 zone of combustion. This is, however, of rare occurrence. 
 
 EFFICIENCY OF GAS PRODUCERS. 
 
 The object of the gas producer is to convert the solid fuel 
 into gas, and this (as already described) always involves 
 the expenditure of some heat, so that the heating power 
 of the gas will always be less than that of the solid fuel 
 from which it is derived. The smaller the difference 
 that is, the nearer the heat obtained by the combustion 
 of the gas approaches that which could be obtained by 
 the direct combustion of the solid fuel from which the 
 gas is made the greater will be the efficiency of the 
 producer. 
 
 If H be taken as the heating power of lib. of coal or 
 other fuel from which gas is being made, H' the heating 
 power of the gas derived from lib. of the fuel, and H" the 
 heat evolved in the producer, then obviously, if all the 
 fuel be consumed, H = H' + H". 
 
 The efficiency of the producer will be the ratio 
 
 TTf TT' 
 
 of H': HOT , so that it may be written E=-fj-. 
 
 If there were no heat evolved in the producer, then 
 obviously H' would be equal to H, and the ratio would 
 be 1. This can never be attained, but the nearer it is 
 approached the more efficient is the producer. 
 
 To take as an example the simple producer gas 
 made from charcoal without steam, H = 8080 and H' -- 
 
 5588, so that E= = "691, or 69-1 per cent, ; 
 
 whilst in the case of the example of steam-enriched 
 gas considered above PI -- 8080 H' 6591, so that 
 
 E = = -81, or 81 per cent. ; and in the case of a 
 
 oUoU 
 
 coal-fed producer, it may be higher still. In practice 
 the efficiency will rarely be above 80 per cent., but with 
 well-constructed producers and careful working it should 
 reach that, or even 85 per cent. 
 
EFFICIENCY OF GAS PRODUCERS. 43 
 
 The efficiency will obviously be reduced by any action 
 which tends to cause the evolution of heat in the 
 producer, and therefore it is very much reduced by the 
 presence of carbon dioxide in the gas. 
 
 It is assumed in the above statement that the gas is 
 burnt cold. If it is used hot in such a way that the 
 sensible heat of the gas can be utilised the efficiency will 
 be higher, as all the heat evolved in the producer will not 
 be lost. 
 
 It is quite obvious that the minimum amount of heat 
 that must be evolved in the producer to keep the produc- 
 tion of gas going on will be that required to balance the 
 sources of loss of heat and keep the producer at the 
 required temperature. 
 
 Losses of Heat in Producer. There are several sources of 
 loss of heat in the producer, none of which can be com- 
 pletely prevented, but all of which should be reduced to 
 a minimum. 
 
 (1) Heat carried off by the escaping gas. The gas 
 always leaves the producer at a high temperature, some- 
 times as high as 600 C. (1,000 F.),and thus a large amount 
 of heat may be carried away. One pound of carbon will 
 give about 6' 7lbs. of producer gas with a specific heat of 
 about -245, so that the heat carried away will be 6'7 x -245 
 = 1-64 units for each degree of temperature of the escaping 
 gases per pound of fuel, or at 600 C. 985 units. As 
 each pound of carbon can only evolve 8,080 units, this will 
 be about 12 per cent, of the total available heat. Ten 
 per cent, is a very usual amount to be thus carried away, 
 but it may be much higher, especially if undecomposed 
 steam bfe passing through the producer or if the gas 
 contain a large quantity of hydrogen, as both of these 
 have a Very high specific heat. For economical working, 
 therefore, unless the gas is to be used hot and the 
 sensible heat thus utilised, the temperature of the 
 escaping gases must be kept as low as possible. With 
 m#st forms of producer in use it is, however, impossible to 
 keep the escaping gas at a low temperature without unduly 
 cooling the mass of fuel, which is likely to produce greater 
 evils. 
 
 (2) Loss of heat by radiation. The mass of hot fuel 
 is surrounded by walls which are exposed to the air, and 
 from which radiation must be taking place. The 
 
44 EFFICIENCY OF GAS PRODUCERS. 
 
 thicker the walls the less heat will be lost through them. 
 It is therefore not advisable that the producer should 
 be a mere shell of iron lined with a thin layer of brick- 
 work. Radiation may be much reduced by building the 
 producers in banks of from six to twelve, instead of 
 singly. 
 
 (3) Heat carried out in the ashes. This is never large 
 in amount, and in modern producers is so much reduced 
 as to be of no importance. Assuming the fuel to contain 
 10 per cent, of ash having a specific heat of '2, and that it 
 be drawn at a temperature of 600 C., the loss will only be 
 600 X *02 == 12 units for each pound of fuel consumed. 
 
 (4) In some types of producer fuel may escape 
 combustion and pass away in the ashes. The amount 
 thus lost should not be large even with bar-bottom 
 producers, but it will necessarily vary with the quality of 
 the fuel and the care with which the producer is attended. 
 Five per cent, is a common loss, but it may reach 10 
 per cent., or even more, and cases have been quoted in 
 which it has reached 30 per cent. The proportion of fuel 
 actually gasified to that supplied is called the grate 
 efficiency of the producer. Assuming the loss of fuel in 
 the ashes to be 10 per cent., the grate efficiency will be 
 9, or 90 per cent. 
 
 The true efficiency of a producer will, of course, be 
 the efficiency, as before defined, multiplied by the grate 
 efficiency. 
 
 Thus in the case of simple producer gas made in a 
 producer having a grate efficiency of *9 the real efficiency 
 would be -691 X '9 = '621 = 62-1 per cent. 
 
 Use of Hot Gas. In describing the efficiency of a gas it 
 has been assumed that the gas is burnt cold. If it be 
 burnt hot so that the sensible heat of the gas can be 
 utilised in furnace heating the efficiency will, of course, be 
 somewhat higher, and the loss of heat in the producer 
 will be less. The heat obtained by the combustion of 
 lib. of the hot gas (E'\ i.e., the effectual calorific power of 
 the hot gas, will be the heat evolved by the combustion 
 of the cold gas added to heat carried over by the hot 
 gas that is, it will be CP + (W X S X T) where W is 
 the weight of the gas per Ib. of fuel consumed, S its 
 specific heat, and T its temperature above that of the air, 
 the last term giving the sensible heat of the gas in 
 
EFFICIENCY OF GAS PRODUCERS. 45 
 
 thermal units. The efficiency of the gas will, of course, be 
 increased, and the hot gas efficiency will equal the cold 
 gas efficiency 
 
 Sensible heat of gas from lib. of fuel 
 
 ~77~ , , H f + WST 
 
 Calorific power of fuel E - 
 
 There is another point which has to be taken into account 
 in considering the efficiency of a gas producer which is 
 usually neglected. If the gas is made from coal it will be 
 laden with tarry matter, and if the gas mains be short 
 this will be carried forward and will be burnt, whilst if 
 the mains be long it will be wholly or partially condensed 
 in the mains. In any case the tarry matter is condensed 
 in taking the sample for analysis, and thus is not taken 
 into account in the analysis. The amount of tar is 
 considerable, and may sensibly increase the calorific 
 power of the gas as burnt, and therefore the efficiency of 
 the producer. The question of tar in producer gas will 
 be considered more fully later. 
 
 In a paper read before the Institute of Civil Engineers 
 in 1896, Mr. C. T. Jenkins describes a method of 
 calculating the efficiency of gaseous fuels, and gives a 
 considerable number of examples. 
 
 The formula he uses for the gas used cold is 
 Efficiency = M x K x G 
 
 ~~H~~ 
 
 Where M is the heat of combustion of the gas for each 
 kilogramme of carbon contained in it, which he calls the 
 " figure of merit " of the gas, K is the proportion of 
 carbon in the coal, G is the proportion of carbon which is 
 gasified, and H is the heat of combustion of one kilo- 
 gramme of the coal used for making the gas. If the 
 whole of the carbon is gasified, G becomes 1, and the 
 
 efficiency is , and M K is the calorific power of the gas 
 
 per kilogramme of the coal. Pounds could, of course, 
 be substituted for kilogrammes without altering the 
 proportion, and " figure of merit " M could then be taken 
 as the heat of combustion of the gas for each pound of 
 carbon it contains. The hot gas efficiency he gives as 
 cold gas efficiency x 
 
 -. sensible heat per cubic metre of the gas *| ' 
 calorific power of the gas / 
 
CHAPTEK V. 
 
 CHIMNEY DRAUGHT PRODUCERS. THE OVERHEAD 
 COOLING TUBE. FORCED DRAUGHT PRODUCERS. 
 BLOWERS. AMOUNT OF STEAM KEQUIRED. 
 
 The proper supply of air and steam to the producer is a 
 matter of the utmost importance for successful working. 
 
 CHIMNEY DRAUGHT PRODUCERS. 
 
 In the early types of producer the ashpit was open 
 and the draught was of the character of a chimney 
 draught, no steam being used, or only so much as could 
 be drawn in with the air, this being supplied either by 
 blowing a steam jet or a water jet under the bars, or 
 by keeping the ashpit full of water, which was evaporated 
 by the heat radiated from the fire bars or by the hot 
 ashes falling into it. In such a producer the amount 
 of steam used was very small. 
 
 It appears at first sight as if the only conditions under 
 which a chimney draught could be used would be when the 
 producer was at a much lower level than the furnace, so 
 that the gas had to pass upwards a condition that could 
 very rarely be arranged. Sir W. Siemens overcame this 
 difficulty by the introduction of the overhead cooling 
 tube connecting the gas producer with the furnaces. 
 
 The gas from the producer passed into a vertical 
 brick stack 8ft. to 12ft. high, thence by a horizontal tube 
 to near to the furnaces, which were intentionally placed at 
 some distance from the producers, and then down by 
 another vertical tube to the ports, or to an underground 
 flue. The set of tubes thus arranged acted as a syphon 
 to draw the gas over. The gas in the up-comer tube 
 being hotter was much lighter than the cooler gas in the 
 down-comer tube, and thus a syphon was produced, the 
 legs of which were of equal length, but the gas in the one was 
 much heavier than the gas in the other, thus producing a 
 draught, and at the same time cooling the gas, so that a 
 large proportion of the tar was condensed in the cooling 
 tube. Siemens says that the cooling tube should have 
 a surface of not less than 60 sq. ft. per producer. 
 
CHIMNEY DRAUGHT PRODUCERS. 47 
 
 Siemens thus explains the action of the tube. "The 
 gas rising from the producer at a temperature of 
 1,100 Fah. is cooled as it passes along the overhead 
 tube, and the descending column is consequently denser 
 and heavier than the ascending column of the same 
 length, and continually overbalances it. The system 
 forms, in fact, a syphon in which the two limbs 
 are of equal length, but one is filled with a heavier 
 liquid than the other. The height of cooling tube 
 required to produce as great a pressure as would be 
 obtained by placing the gas producer, say, ten feet deeper 
 in the ground may be readily calculated. The temperature 
 of the gas as it rises from the producer has been taken as 
 1,100 Fah., and we may assume that it is cooled in the 
 overhead tube to 100 Fah. an extent of cooling easily 
 attained. The calculated specific gravity, referred to 
 hydrogen, of the gas of which I have quoted the analysis, 
 being 13'4. We obtain the following data : 
 
 Weight of gas per cubic foot at 1,100 Fah. = '0221b. 
 
 100 Fah. = -OGllb. 
 
 Weight of atmosphere per 
 
 cubic foot at ................. 60 Fah. = '0761b. 
 
 and from these we have on the one hand the increase of 
 pressure per foot of height in the flue rising directly from 
 the gas producer '076 "022 '0541b. per square 
 foot, and on the other hand the excess of pressure at the 
 foot of the down-take from the cooling tube over that at 
 the same level in the flue leading up from the gas 
 producer (per each foot of height of the cooling tube) = 
 061 -- -022 = -0391b. per square foot. The height of 
 the cooling tube above the level of the flue which will be 
 sufficient to produce the required pressure equal to 
 
 _lQftr-of heated gas column is therefore X 10ft. = 
 
 13ft. lOin., or say 14ft." The cooling tube cools the gas 
 and condenses a large amount of the tar and water, and 
 this Siemens contended was an advantage. 
 
 It will be seen that with the cooling tube, the air 
 current must be very sluggish, and therefore the com- 
 bustion must be slow, for the pressure will be very small. 
 The layer of fuel will be much thicker in a producer 
 than in an ordinary fireplace, though in a " chimney 
 draught " producer it can never be very thick, and this 
 
 * Siemens' Collected Works, Vol. I., p. 222. 
 
48 FORCED DRAUGHT PRODUCERS. 
 
 will retard the passage of the air. Such a producer 
 must also work with an open hearth, so that air can 
 have free access, and therefore very little steam can be 
 used. The open-grate chimney draught producer is now 
 very little used. 
 
 When the air is supplied under pressure by a fan, or 
 otherwise, the conditions are considerably changed, a 
 much greater pressure can be used, and therefore com- 
 bustion can be made much more rapid, the hearth can 
 be closed, and air and steam supplied in any required 
 proportions. The overhead cooling tube becomes 
 unnecessary, the producers can be put as near the 
 furnaces as is convenient, and underground flues can be 
 used. Air and steam can be supplied in any convenient 
 way, the air by means of a fan or blower, and the steam 
 by a jet from a boiler, but as the air and steam are 
 always required together, a steam jet blower is almost 
 always used. 
 
 BLOWERS. 
 
 Steam Jet Blower. The principle of this blower is very 
 simple. A jet of steam is blown into a tube leading to 
 the producer, and carries with it, by friction, the air 
 required. 
 
 Siemens designed a steam jet blower for the purpose, 
 which he described in a paper read before the Institution 
 of Mechanical Engineers in 1872, and though simpler 
 forms are now generally used for gas producers, this one 
 is of great interest. It is shown in section in Fig 2. 
 Siemens thus describes it : - 
 
 " A very thin annular jet of steam is employed in the 
 form of a hollow cylindrical column discharged from 
 the annular orifice between the two conical nozzles, the 
 steam being supplied from the pipe C into the space 
 between the two nozzles. The inner nozzle can be 
 adjusted up or down by the hand screw D so as to 
 diminish or increase the area of the annular orifice 
 between the two nozzles for regulating the quantity 
 of steam issuing. The air to be propelled by the steam 
 jet is admitted from the pipe E through an exterior annular 
 orifice surrounding the steam jet, and also through 
 the centre of the hollow jet. The tube G, into 
 which the steam jet issues, is made of a conical shape 
 at the bottom, so as to form with the outer nozzle 
 
STEAM JET BLOWERS. 49' 
 
 a rapidly converging annular passage, regulated by adjust- 
 ing the outer nozzle by means of the nut H at the bottom. 
 The tube G continues to diverge very gradually for some 
 distance above the jet orifice, the length of the convergent 
 portion increasing with the outer annular air orifice, and 
 also with the steam pressure employed." " A tapering 
 spindle I is sometimes fixed in the centre of the inner 
 nozzle and carried up through the mixing chamber G, 
 for the purpose of preventing reflux through the centre of 
 the combined current. 
 
 UJJ 1 D 
 FIG. 2. SIEMENS' STEAM JET. 
 
 " The rationale of this arrangement is as follows r 
 First, by gradually contracting the area of the air 
 passages on approaching the jet the velocity of motion 
 of the entering air is so much accelerated before it 
 is brought into contact with the steam that the 
 difference in the velocity of the two currents at the point 
 where they come together is much reduced, and in 
 consequence the eddies which previously impaired the 
 efficiency of the steam jet are to a large extent obviated, 
 and a higher useful effect is realised ; secondly, by the 
 
50 STEAM JET BLOWERS. 
 
 annular form of the steam jet the extent of surface 
 between the air and the steam is greatly increased, and 
 the quantity of air delivered is very much augmented in 
 proportion to the quantity of steam employed."* 
 
 By means of this jet used as an exhauster Siemens 
 obtained a vacuum of 24in. of mercury, and with it he 
 made many experiments to elucidate the laws according 
 to which the jet blower acts. 
 
 Principles of the Blower. As the jet of steam rushes from 
 the orifice into the air it draws a considerable quantity of 
 air with it, and if it be directed into a tube a stream of 
 air and steam will be obtained. Apparatus on exactly 
 the same principle is used for various purposes with 
 fluids other than air and steam. In the trompe used in 
 blowing the primitive Catalan forge for the manufacture 
 of malleable iron, a current of water was the moving power, 
 the air being carried along by it and discharged into the 
 forge, and in the ordinary injectors used for feeding 
 steam boilers a jet of steam is made to carry forward a 
 stream of water. 
 
 Sir W. Siemens says : " The result of a long series of 
 experiments with this form of steam jet for exhausting 
 and compressing air have led to the following con- 
 clusions : 
 
 " First, that the quantity of air delivered per minute 
 by a steam jet depends 011 the extent of surface of contact 
 between the air and steam irrespective of the steam 
 pressure up to the limit of exhaustion or compression that 
 the jet is capable of producing. 
 
 " Second, that the maximum degree of vaccum or of 
 pressure attainable increases in direct proportion to the 
 steam pressure employed, other circumstances being 
 similar. 
 
 " Third, that the quantity of air delivered per minute 
 within the limits of effective action of the apparatus is in 
 inverse relation to the weight of air acted upon, and a 
 better result is therefore obtained in exhausting air than 
 in compressing it. 
 
 " Fourth, the limits of air pressure attainable, with a 
 given pressure of steam, are the same in compressing as in 
 exhausting within the limit of a perfect vacuum in the 
 latter case."t 
 
 * Siemens' Collected Works, Vol. I., p. 142. 
 t Siemens' Collected Works, Vol. I., p. 143. 
 
STEAM JET BLOWERS. 51 
 
 There are certainly other conditions besides steam 
 pressure and the area of aperture of the steam jet which 
 modify the action. If a jet of steam be blown from a 
 nozzle so shaped that the jet is a cylinder, it will retain 
 its form for a considerable distance, and therefore can 
 only draw in the air by surface friction. On the other 
 hand, if the jet be of such a form that the issuing jet of 
 steam is conical, the area of section will increase rapidly, 
 the steam will be mixed with the air, and the action will 
 certainly not be merely due to friction of the air at the 
 surface of the steam jet. The molecules of air being 
 mixed with those of steam there will be impact, and the 
 air will be swept forward by the steam, it has been said, 
 " much in the same way as a piston would do, but, of 
 course, with less solidity of action." In this case the 
 propelling force would seem to be the momentum of the 
 steam, which, in its turn, is due to the mass and the 
 velocity. The best results seem, on the whole, to be 
 obtained with solid diverging jets, and some engineers, 
 after experimenting with hollow jets, have given them 
 up, and returned to solid jets. 
 
 The whole subject of the propelling force of the steam 
 jet needs careful experimental examination. 
 
 A blower therefore consists essentially of two parts, 
 the steam jet and the tube into which it blows. 
 
 Blower Tube. The receiving tube consists usually of two 
 portions, a short upper portion expanding upwards, and a 
 lower portion joining this at its narrowest point and expand- 
 ing downwards. The best size has been arrived at by 
 experience rather than from theory, and very few experi- 
 ments have been made on the influence of varying size 
 and form of the receiving tubes. As pointed out by 
 Siemens, the upper part of the tube should be opened 
 out into an inverted cone near the bottom of which the 
 point blower should be put. 
 
 The Simple Jet Blower. In this type of blower the steam 
 jet is a simple tube, as shown in Fig. 3, the dimensions 
 given being those commonly used. 
 
 Annular Jets. A solid steam jet of small diameter, say 
 jin., offers a very small surface of contact, so that the 
 quantity of air carried forward is small in proportion to 
 the amount of steam used, and as in a gas producer the 
 quantity of steam that can be used with advantage is 
 small, an excess of steam is likely to be supplied. 
 
52 
 
 ANNULAR JETS. 
 
 To overcome this difficulty annular jets have been 
 devised. The jet is made much larger in diameter, but 
 has a central air pipe, so that the steam escapes in the 
 form of a ring, and air is admitted both inside and outside 
 the jet. If the amount of air carried in depended entirely 
 on the area of contact between the steam and air, a 
 much larger quantity of air could thus be carried through 
 by a given quantity of steam. 
 
 The annular blowers have, however, not been 
 altogether successful. The layer of steam is excessively 
 thin, say /^in. or less, so that the continuity of the 
 
 FIG. 3. STEAM JET. 
 
 cylinder of steam is easily broken, and thus the efficiency 
 is impaired, and therefore most users still prefer the solid 
 jet. 
 
 Adjustable Jets. It is often necessary, or at any rate 
 advantageous, to be able to adjust the relative quantities 
 of steam and air, and various blowers have been devised for 
 the purpose. In the annular jet blowers adjustment is com- 
 paratively simple. The best known of this type is the 
 blower of Mr. Thwaite. (Fig. 4). In this two bronze 
 nozzles are fitted, one inside the other, so as to leave an 
 annular steam space, and they are so shaped that by 
 
ARGAND BLOWER. 
 
 53 
 
 raising or lowering the inner tube by means of a screw 
 the width of the annular space can be increased or 
 
 FIG. 4. THWAITE ADJUSTABLE ANNULAR STEAM JET BLOWER. 
 
 diminished, thus increasing or diminishing the supply of 
 steam, whilst the area of contact with the air remains 
 unchanged. 
 
 The Argand Blower. This type of blower (Fig. 5) has 
 been used in the United States, and is said to be very 
 
 sp 
 
 AIR 
 
 FIG. 5. ARGAND BLOWER. S.P., STEAM PIPE. 
 
 efficient, but the author does not know if it has been 
 used in this country. As will be seen from the illustration, 
 
54 STEAM JET BLOWERS. 
 
 the steam is delivered into a ring of circular or ellip- 
 tical section, from which it passes by a large number 
 of small holes, thus giving a very large number of small 
 steam jets. By this means a very large surface of contact 
 between the air and the steam is provided. 
 
 The Korting Blower. In this blower a solid steam jet is 
 used, which blows into an inverted cone like the top of 
 the ordinary blower tube, the bottom of which opens into 
 a second inverted cone into which the mixture of steam 
 and air blows, this opens into a third, and, if required, a 
 fourth, so that there are from three to five inverted cones 
 through which the steam and air passes into the air tube, 
 the volume of the gas being increased and its speed 
 diminished in each. 
 
 A pressure of from Sin. to 12in. of water can be 
 obtained. The following details are given by Messrs. 
 Korting : 
 
 No. of blower ... 01234 5 6 7 
 Air delivered ) 
 
 per minute in V 150 400 650 900 1500 2000 3000 4000 
 
 cubic feet ... ) 
 Bore of steam IT -i ^ r 
 
 pipeininches} t f ' 1 1* U If 2J 
 
 Diameter ofl 
 
 air conduit 4 8 9 10 12 13 16 18 
 
 in inches ... J 
 
 The supply of steam can be regulated by~means of 
 a spindle, which can be lowered into the top nozzle. 
 
 Granger's Blower. This is a solid jet adjustable blower. 
 It has three separate nozzles of different sizes, so arranged 
 that by turning a handle any one of them can be brought 
 into use, but never more than one at the same time, 
 each jet as it comes into use coming at the same time 
 into a position so as to be central with the tube. 
 
 FIG. 6 A B C JETS. H, HANDLE FOR BRINGING ANY PARTICULAR 
 JET INTO ACTION. 
 
BLOWER TUBE. 55 
 
 This blower seems to be one of the most efficient, and 
 is very satisfactory in action. For ordinary purposes the 
 smallest blower is used, but as any one of the others may 
 be put into action varying proportions of steam and air may 
 be obtained. If the amount of air depends only on the 
 surface of contact, then as the surface of contact, i.e., 
 
 FIG. 7. 
 
 the circumference of section, varies as the radius, and 
 the area varies as the square of the radius, the 
 changing of the nozzle will increase both air and steam, 
 but will increase the amount of steam in a larger ratio 
 than the amount of air. The writer has no data by which 
 he can determine to what extent this actually is the case. 
 Other types of blowers have been suggested, but these 
 are the principal ones in use. 
 
 Blower Tube. The form of the blower tube is of great 
 importance. (See Fig. 8.) The upper part has always the 
 form of the frustum of an inverted cone, and at the 
 
 Fio. 8. TUBE FOR STEAM JET BLOWER. 
 
 bottom of this the current may be considered to be 
 formed. It then widens out, so that, as the current 
 of air and steam flows, its diameter is increased, and 
 therefore its speed is reduced, till at the bottom of the 
 tube it is delivered to the producer. 
 
 Power of Blowers. The air is not required to be sent to 
 the producer at a high pressure, from 5in. to lOin. of 
 
.56 AMOUNT OF STEAM REQUIRED. 
 
 water being that usually used, though some blowers will 
 give up to 12in. 
 
 Mr. Thwaite gives the following table of the power 
 of his annular blower : 
 
 Diam. f S te amj et. ^.^ute'af 
 Inches. atmospheric pressure. 
 
 I 60 
 
 T 9 * 250 
 
 | 350 
 
 1 1,200 
 
 1J- 2,000 
 
 Steam at 601bs. pressure. 
 
 Amount of Steam Required. The best proportions of steam 
 and air cannot be rigidly fixed, the more steam that is used 
 the better, until a limit is reached, this limit depending 
 mainly upon the amount of heat that is available for 
 decomposing the steam without unduly cooling the 
 producer, and this will depend on the loss of heat in the 
 producer itself. The average proportions when a producer 
 is working well are about 10 parts steam and 90 parts air 
 by volume, rising sometimes to 12' 5 parts of steam to 
 87'5 parts air, but rarely passing beyond this. 
 
 Taking 10 per cent, of steam by volume as being a 
 good working proportion, this will be about 6 per cent, of 
 steam by weight, and about one-fifth of the carbon will be 
 burnt by steam and four-fifths by air. 
 
 Assuming 6 per cent, of steam by weight, it is very 
 easy to calculate the amount of fuel that will be 
 consumed. 
 
 Since lib. of carbon will combine with l'331bs. oxygen 
 to form carbon-monoxide, and air contains 23 per cent, by 
 weight of oxygen, the amount of air required to burn lib. of 
 
 carbon will be - - = 5'81bs., therefore lib. of 
 
 O 
 
 air will burn = '171 Ib. of carbon. 
 
 o'o 
 
 One pound of carbon in decomposing steam will also 
 combine with l'331bs. of oxygen, and this will be contained 
 in l'491bs. of steam, therefore lib. of steam will burn 
 
 .. TQ = '671b. of carbon, so that for lOOlbs. of the gaseous 
 JL 4y 
 
 mixture 
 
 '941bs. of air = '171 X 94 = 161bs. of carbon burnt by air. 
 61bs. of steam='67 X 6 = 4' ,, ,, ,, steam. 
 
 100 20- 
 
AMOUNT OF STEAM REQUIRED. 57 
 
 If loss of heat in the producer could be guarded 
 against, a much larger proportion of steam could be used. 
 One engineer of large experience has stated to the author 
 that 7 per cent, by weight is the maximum amount of 
 steam which should be used in an ordinary steam blown 
 producer. 
 
 Assuming the proportions above given to be correct, 
 it is easy to ascertain what amount of steam will be 
 required to work a gas producer. In all such calculations 
 only the fixed carbon of the fuel must be taken into 
 account, as all volatile matter will be expelled before the 
 residue comes under the action of the air and steam. The 
 amount of fixed carbon in and the amount of gas given 
 off by the fuel should therefore always be determined. 
 
 The amount of steam required will be Gibs, for each 
 201bs. of carbon burnt, or '31bs. of steam for each pound 
 of carbon. 
 
 Assuming the coal used to yield 60 per cent, of fixed 
 carbon, '6 X *3 = "ISlbs. of steam will be required for 
 each pound of coal consumed. To be on the safe side, 
 the boilers should be capable of supplying two or three 
 times this amount. 
 
 Each pound of carbon will require 5'81bs. of air, or lib. 
 ofcoal of the composition assumed will require 3'481bs. 
 of air. 
 
 As lib. of air under normal conditions of pressure and 
 temperature occupies 12 "36 cub. ft., the volume of air 
 required will be 58 '1 cub. ft. for each pound of carbon, or 
 34'9 cub. ft. for each pound ot coal consumed. 
 
 The steam should be supplied at a high pressure, GOlbs. 
 to 751bs. being usually used. 
 
CHAPTEK VI. 
 
 CHIMNEY DRAUGHT PRODUCERS. CLOSED - HEARTH 
 PRODUCERS. BAR-BOTTOM PRODUCERS. SOLID 
 BOTTOM PRODUCERS. WATER - BOTTOM PRO- 
 DUCERS. AUTOMATIC PRODUCERS. BLAST- 
 FURNACE PRODUCERS. 
 
 THE early forms of producer, such as those of Bischof 
 and Ebelman, were little more than enlarged fireplaces, 
 and for many reasons were not efficient. In 1861 
 Siemens introduced his gas producer, which did not 
 differ in principle from those which had gone before, but 
 which became a success, not so much on account of any 
 improvement in the producer itself as because it was for 
 the first time associated with the regenerative system of 
 burning the gas, the regenerative gas furnace having 
 just been invented by Siemens. 
 
 The Siemens producer (Fig. 9) was a firebrick 
 chamber about 8ft. square and 6ft. or 8ft. deep, narrowed 
 at the bottom, by the front wall being sloped inwards, 
 and provided with a series of firebars. The action of 
 such a producer is very simple. Air enters through the 
 firebars, and combustion takes place just as in an ordinary 
 fireplace, the hot gases passing upwards are largely 
 reduced to carbon monoxide by the action of the hot 
 coke, and the volatile matters are distilled from the coal 
 in the upper regions of the producer, aod the gas thus 
 produced mixes with the carbon monoxide, carbon 
 dioxide, and nitrogen from the combustion of the coke. 
 
 The draught is produced entirely by the chimney, or 
 rather by the overhead cooling tube, and is therefore a 
 natural as distinguished from a forced draught. If the 
 furnace could be placed at a considerable elevation above 
 the producer the gas would tend to rise and produce 
 sufficient pressure, but this is rarely possible, the furnaces 
 and the producer being in most cases necessarily at about 
 the same level. 
 
 The draught obtained is only about '541bs. per square 
 foot or '0031bs. per square inch, or, say, rt>m- of water. 
 
CHIMNEY DRAUGHT PRODUCERS. 59 
 
 Such a producer can never be very efficient. The 
 draught is small, therefore the combustion is slow, rarely 
 reaching lOlbs. of fuel per square foot of grate area per hour 
 or less than that consumed in an ordinary boiler grate. 
 There is always the possibility of the loss of fuel through 
 the bars, so that the grate efficiency is low. The grates 
 
 FIG. 9. SIEMENS GAS PRODUCER (OPEN TYPE). 
 
 cannot be made of large size, as they must be of such 
 form and size as to allow the ready removal of clinkers, 
 5ft. or 6ft. being the maximum satisfactory width. 
 Assuming the hearth to be 5ft. X 8ft., this gives an 
 area of 40ft., and with a combustion of lOlbs. per hour 
 will give 4001bs. per hour per producer. The hearth 
 
.60 
 
 CHIMNEY DRAUGHT PRODUCERS. 
 
 being open, very little steam can be used ; indeed, usually 
 the only water vapour supplied is that evaporated from 
 water in the ashpit or sprinkled on the bars, and there- 
 fore the gasification is not likely to be economical. The 
 layer of fuel must also be thin, so that usually a good 
 deal of carbon-dioxide is present in the gas, and in order 
 to produce a draught the gas must leave the producer at 
 a high temperature, the sensible heat being completely 
 lost in the cooling tube. 
 
 On the other hand, the producer is cheap and easy to 
 erect and to manage, and requires no steam supply ; but 
 the disadvantages so far outweigh the advantages that 
 open producers have almost ceased to be used. There 
 are cases, however, such as when the producer can be 
 practically made a fireplace, and the hot gas passed at 
 once to the furnace, where this type of producer can be 
 satisfactorily applied. 
 
 The following is an analysis of gas made in a producer 
 of this type, and will show its general character : 
 
 
 By Volume. 
 
 By Weight. 
 
 Methane &c 
 
 4-40 
 
 2'5 
 
 Carbon monoxide 
 Carbon dioxide 
 Nitrogen 
 
 25-60 
 4-30 
 65-70 
 
 25-5 
 6-8 
 65'2 
 
 
 
 
 
 100-0.0 
 
 100-00 
 
 Calorific Power. 
 
 C.U. B.Th.U. 
 
 Methane -025 x 12000 = 300-0... -025 x 21000= 525 
 
 Carbon monoxide -255 x 2400-612- ...-255x 4320-1101-6 
 
 912-0 1626-6 
 
 lib. of gas will contain 'I462lb. carbon. If all the 
 carbon were burnt to carbon dioxide it would evolve 
 1181-3 C.U., or 2126-3 B.Th.U., and the hydrogen burning 
 to water would give213'6 C.U., or 379B.Th.U., so that the 
 heat of combustion of the fuel used would be 1391'8 C.U., 
 
 Q12 
 or 2495 B.Th.U., and the efficiency of the producer =T^QQ= 
 
 65 '5 per cent. 
 
CLOSED-HEARTH PRODUCERS. 
 
 61 
 
 CLOSED-HEARTH PRODUCERS. 
 
 All modern producers are worked with closed hearths f 
 the steam and air being supplied together. A much 
 larger quantity of steam can thus be used, and it 
 can be supplied much more rapidly and at a higher 
 pressure. As the gas does not need to be hot to 
 produce a draught, it can be cooled to a much greater 
 extent before leaving the producer, if this be deemed 
 desirable. A much richer gas can be obtained with, 
 at the same time, much more rapid gasification, and the 
 
 FIG. 10. SIEMENS CLOSED-HEARTH PRODUCER. 
 
 process is much more completely under control. The 
 overhead cooling tube, which gives a great deal of trouble 
 from the accumulation of tar, also becomes unneces- 
 sary, and is usually replaced by underground conduits. 
 Siemens very early recognised the advantages of steam 
 blowing, and suggested the use of his producer with a 
 closed hearth, air and steam being blown beneath the- 
 bars. 
 
 Closed producers may be divided into five groups,, 
 though it is impossible to arrange a classification that 
 
62 
 
 CLOSED-HEARTH PRODUCERS. 
 
 will be satisfactory from all points of view, and some 
 producers might be put into more than one group : 
 
 1. Bar-bottom producers. 
 
 2. Solid-bottom producers. 
 
 3. Water-bottom producers. 
 
 4. Automatic producers. 
 
 5. Blast-furnace producers. 
 
 I. Bar-bottom Producers. In producers of this type the 
 fuel rests on firebars, exactly as in the earlier Siemens 
 producer ; but the hearth is closed, the air and steam 
 being supplied beneath the bars. Siemens suggested a 
 producer of this type (Fig. 10) by merely closing the 
 front of the ashpit of his producer and blowing air and 
 steam beneath the bars. Another well-known producer 
 
 FIG. 11. THWAITE SIMPLEX GAS PRODUCER. 
 
 of the type is the Simplex of Mr. Thwaite (Fig. 11), 
 modified also in the Twin and Duplex producers, which 
 will be subsequently described; but the best known is 
 
CLOSED-HEARTH PRODUCERS. 
 
 68 
 
 probably that of Mr. Dowson, largely used in the 
 preparation of gas for small motors and similar purposes. 
 
 It is not necessary to discuss these producers in 
 detail, as they are now rarely used except under special 
 circumstances. The disadvantages of this type of 
 producer are easily seen. Clinker accumulates on the 
 bars, and must be removed from time to time by poking. 
 The hearth must therefore be small to allow of easy 
 clinkering, and as unburnt coal may fall through with the 
 ashes the grate efficiency will be low. It is impossible to 
 
 FIG. 12. THE DOWSON GAS PRODUCER. 
 
 obtain very rapid gasification, rarely above 201bs. of fuel 
 per square foot of grate area per hour. The bars can, 
 however, be clinkered without actually stopping gas 
 production, though this must necessarily be checked. 
 
 For small plants these producers are still used, as 
 they are easy to erect and to manage, but for large 
 installations they have been almost completely abandoned. 
 
 The Dowson Producer. (Patent, 1878, No. 3,997 ; 1881, 
 No. 2,895.) This producer, however, calls for remark, 
 owing to its extensive use in the production of gas for 
 small gas engines. 
 
64 CLOSED-HEARTH PRODUCERS. 
 
 The generator is cylindrical, and consists of an iron 
 casing lined with firebrick, and is provided at the bottom 
 with firebars, on which the fuel is consumed, and 
 beneath which a jet of air and steam is supplied. No 
 special boiler is needed, but the steam is produced and 
 superheated in a coil of pipe contained in a separate 
 superheating furnace, which, when once the producer is 
 started, is heated by part of the gas. Coal, anthracite, 
 
 FIG. 12A. DOWSON'S GAS GENEBATOR. 
 
 or coke may be used ; but when the gas is to be used for 
 gas engines, one of the two last named is preferable, 
 or the gas is purified by washing, as described later. 
 
 Mr. Dowson has recently patented a new form of 
 producer, which is shown in Fig. 12A. It is a bar- 
 bottom producer, and the chief peculiarity is that it is so 
 
CLOSED-HEARTH PRODUCERS. 65 
 
 arranged that air can be aspirated through or supplied 
 by a blower, as may be required. It comprises a casing A 
 partly lined with firebricks B, an outer casing C with air 
 inlet D and space E containing loose pieces of iron. 
 There is a water supply F to chamber G- with overflow H 
 and outlet I. When air is drawn into the generator by 
 the action of the engine connected therewith, the air 
 pressure in the chamber J is reduced, and water is 
 thereby caused to flow through the outlet I from the 
 chamber G where the pressure is momentarily in excess. 
 The water thus admitted into the chamber J flows to 
 one or more channels K K where all or part of it is 
 evaporated, and the steam mixes with the heated air in 
 inclosed space E. If any excess of water falls from the 
 channels K K it will fall on the loose pieces of iron in 
 the inclosed space E, and will then be evaporated by 
 coming in contact with heated surfaces. 
 
 When air is forced into the generator by means of a 
 blower or pump, the overflow H is raised so that the 
 head of water in the chamber G is sufficient to overcome 
 the pressure caused by the blower or pump in the 
 chamber J. The heated air and the water vapour 
 formed in the inclosed space E pass downwards through 
 the passage L to the lower part of generator M and 
 thence upwards through the fire. The gas formed 
 leaves the fire at N, and after passing through the 
 passage round the fuel container T it leaves the 
 generator at P. When the generator is worked by the 
 suction of an engine, the level of the water in G can be 
 regulated by the height of the overflow H, so that none 
 will enter the generator until the engine sucks, and then 
 it will automatically draw in the quantity of water 
 required to be vaporised. In this way the quantity 
 of water admitted and the quantity of steam produced 
 are governed by the engine, and are in proportion to 
 the quantity of gas produced in the generator. In some 
 cases an excess of water is purposely allowed to drain 
 from the space E on to the floor Q of the generator so 
 that some water may be vaporised by the heat of the 
 fire on the grate R. An overflow for any excess of 
 water is provided at S. 
 
 Fig. 13 shows a bar bottom producer used in Sweden 
 for gasifying wood. 
 
 Solid-bottom Producers. In these producers the fuel 
 rests on the solid bottom of the combustion chamber, or, 
 
66 
 
 CLOSED-HEARTH PRODUCERS. 
 
 rather, when the producer is at work there is a layer of 
 ash or clinker on the bottom, upon which the fuel in 
 process of gasification rests. The air is blown into the 
 mass of ash and fuel either near the bottom or higher up, 
 and the clinker is drawn off from time to time through 
 doors placed near the bottom, so that the charge can 
 descend, a certain thickness of clinker being always left. 
 
 FIG. 13. SWEDISH GAS PRODUCER FOR USING WOOD. 
 
 As there are no firebars, and the fuel is kept high in 
 the producer, the combustion is almost if not quite 
 perfect, and the grate efficiency approaches 1. The air 
 and steam are supplied into the centre of the hot mass of 
 fuel, and the combustion is rapid and complete. The air 
 supply may be either by a central pipe or by a passage 
 passing across the chamber. So there are no bars to 
 be clinkered, and the ash only need be withdrawn 
 periodically. This can be done from both sides or from 
 several points in the circumference if necessary, and the 
 hearth can be made larger than when bars are used. 
 
 Essentially, therefore, such a producer consists of a 
 firebrick chamber, round, square, or of any other form, 
 cased with iron, and having a flat or slightly sloping 
 bottom, and an arrangement for blowing in air and steam. 
 The details may be modified to almost any extent, 
 engineers frequently building producers for themselves 
 
CLOSED-HEARTH PRODUCERS. 
 
 67 
 
 to suit their own needs. If a producer of this sort 
 is to be a success, great attention must be given 
 to the arrangements for the supply of steam and air, so 
 that it shall be evenly distributed through the mass, and 
 no portion of the fuel shall escape combustion (this 
 being far more important than in the case of bar-bottom 
 producers, where the bars act as distributors), and to 
 
 FIG. 14. WILSON GAS PRODUCER. 
 
 arrangements for the withdrawal of ashes. If the producer, 
 be too large, or be not properly provided with cleaning 
 doors, it will be impossible to remove the ashes completely. 
 As a rule, a distance of about 2ft. Gin. to 3ft. is as great 
 as it is possible to reach to remove the ashes, unless the 
 charge be held up, when a somewhat greater thickness is 
 
68 CLOSED-HEARTH PRODUCERS. 
 
 allowable. Either, therefore, there must be an efficient 
 means of holding up the charge during cleaning, or the 
 producer must be considerably narrowed at the bottom. 
 Many solid-bottom producers have been designed, but 
 only one or two need be mentioned. 
 
 The Wilson Producer. This is the best known and most 
 widely used of all the solid-bottom producers. It was 
 patented by Messrs. Brook & Wilson in 1876. The 
 original producer was square, but as now used it is always 
 circular. It consists of a shell of firebrick cased 
 with iron (Fig. 14), the internal diameter being 
 usually about 8ft. The air and steam are supplied 
 by a blower into a conical tube which opens into a 
 brick passage running across the producer and com- 
 municating with the interior by a series of rectangular 
 openings. On each side of this air passage is a 
 cleaning door for the removal of the ashes, and narrow 
 doors are placed a little above the level of the air 
 passage, so that a line joining them is at right angles to 
 it. Clinker can be allowed to accumulate to any height 
 that may be desired, and the air and steam passing 
 through this on its way upward becomes hot. The air 
 and steam, as will be seen, are delivered into the centre 
 of the contents of the producer, and combustioi-i is very 
 perfect. The maximum size which such a producer can 
 be made depends on the power of the air to reach the 
 circumference, as, should it fail to do so, fuel would escape 
 combustion and would be lost in the ashes. These 
 producers are made up to 12ft. in diameter, and a con- 
 sumption of 401bs. of fuel per square foot of bottom can 
 be obtained. The gas is also usually richer than that 
 made in bar-bottom producers. 
 
 The clinker has to be removed about once every 
 24 hours. For this purpose the blast is turned off, the 
 narrow side doors are opened, and iron bars are put 
 through, so as to rest on the top of the air passage, thus 
 forming a sort of grate to support the contents of the 
 upper part of the producer whilst the ashes are drawn 
 out. The cleaning doors are then opened and the ashes 
 raked out, the doors are closed, the bars withdrawn, the 
 side doors closed, and the blast put on, the whole opera- 
 tion of cleaning occupying about half an hour. 
 
 Another important part of the Wilson producer is the 
 arrangement for destroying tar. At the top of the pro- 
 ducer a cone of brickwork is built, so as to descend about 
 
CLOSED-HEARTH PRODUCERS. 69 
 
 2ft. 6in. into the producer, and is supported by arches 
 thrown from the lining, so as to form an annular space 
 round the top, communicating with the interior of the 
 producer by the above-mentioned arches, and also with 
 the gas main. As the producer is kept full of coal, 
 distillation can only take place at the top, and the 
 products of distillation must pass downwards through 
 the hot fuel before reaching the gas main. The tarry 
 matters are thus decomposed by the hot coke into 
 carbon, which is afterwards burnt, and permanent gases, 
 which escape. 
 
 The apparatus is efficient and compact. The ordinary 
 size will gasify 4 cwt. of coal per hour. The space 
 occupied is only about 9ft. by 14ft., allowing 126 square 
 feet for coal storage. 
 
 The table shown is an analysis of Wilson gas published 
 by Mr. Wilson. 
 
 
 By Volume. 
 
 By Weight. 
 
 Nitrogen 
 
 55-96 
 
 61'66 
 
 Carbon monoxide 
 Hydrogen 
 
 22-32 
 12-11 
 
 24-59 
 95 
 
 Carbon dioxide 
 Marsh gas 
 
 6-18 
 3-43 
 
 10-65 
 2*15 
 
 
 
 
 
 100-00 
 
 ] 00-00 
 
 It will be readily seen that solid-bottom producers 
 may be modified to almost any extent. Fig. 15 shows a 
 form used at one steel works. The brick air passage is 
 replaced by an iron tube opening by a number of 
 openings into the body of the producer, and com- 
 municating below with an air chamber into which air and 
 steam are supplied by the blowers. Across the producer 
 is fixed an iron bar to carry the ends of the temporary 
 bars used for holding up the charge during cleaning. 
 
 The old type of Siemens open producer can readily 
 be converted into a solid-bottom producer. Fig. 16 
 illustrates the method of doing this. A ridge or brick- 
 work, carrying an air tube, is built up longitudinally 
 along the bottom of the producer, and cleaning doors are 
 arranged at each side of it. 
 
WATER-BOTTOM PRODUCERS. 
 WATER-BOTTOM PRODUCERS 
 
 71 
 
 All solid-bottom producers are intermittent in their 
 action ; that is, they must be periodically stopped for 
 cleaning. If, however, the ashes be allowed to fall into 
 a vessel of water, so arranged that there is a water seal 
 to prevent the escape of gas, the ashes can be removed 
 at intervals without stopping the gas production. Such 
 
 j'jl|^jUi"^Vj.j'jjVtV\{-'f' *^,;j^ i*'!. '''I '-'!.'''.' ^V^'^V.^j jjAVil!A*i^f ^l^'l^.^U^-'?J^ ^ jm^ 
 
 flRISPR^^t * *eT -"Ws' '"* ^A^T "^^"''''^'T^^'^^H-^j 1 !^^ "S^'?r v 
 
 FIG. 16. SIEMENS OPEN PRODUCER CONVERTED INTO A SOLID-BOTTOM PRODUCER. 
 
 a producer is usually called a water-bottom producer. In 
 addition to allowing the ready removal of ashes, the 
 ash is thoroughly cooled, any heat it may bring down 
 being utilised in vaporising some water. 
 
 It has been stated by at least one steel works chemist 
 that, when steel is made in a furnace fired by gas from a 
 water-bottom producer, there is much greater difficulty 
 
72 
 
 WATER-BOTTOM PRODUCERS. 
 
 in keeping down the sulphur in the steel than when dry- 
 bottom producers are used. The author has made exten- 
 sive inquiries among steel makers, and' whilst one or two 
 think this to be the case, the majority have noticed no 
 indication of such an action. Under these circum- 
 stances it does not seem that there is any serious 
 danger in this direction, except, perhaps, when an 
 extremely low sulphur content is required, but he 
 mentions the matter in order to induce those who have 
 the opportunity to make experiments on it. The only 
 
 FIG. 17. THE DAWSON PRODUCER. 
 
 explanation of such a fact will be that certain sulphides, 
 such as iron sulphide (iron pyrites) or calcium sulphide 
 (from calcium sulphate), which might remain in the ash 
 in the case of the dry-bottom producers, might be 
 decomposed by water, the sulphur passing into the gas as 
 hydrogen sulphide, in the case of the water-bottom 
 producer. 
 
 The first water-bottom producer was that of Mr. 
 Dawson ; but as this type has been modified, it will be 
 
WATER-BOTTOM PRODUCERS. 73 
 
 sufficient to describe the later type of Dawson producer, 
 patented in 1894, No. 15,150. 
 
 The Dawson Producer. This producer (Fig. 17) consists 
 of a circular shell of masonry cased with iron plates, 
 supported on short columns, the casing plates being 
 continued downwards into a water trough so as to 
 give a water seal all round sufficient to prevent the 
 escape of gas. The air and steam are supplied in 
 the usual way, and are delivered by means of a 
 vertical pipe covered with a hood, which passes well up 
 into the mass of fuel. Poking holes are provided round 
 the circumference and at the top. The ashes can be 
 drawn all round the circumference, and as the blast need 
 not be stopped, the producer can be worked continuously. 
 
 The Duff Producer. Of the modern water-bottom 
 producers the best known and most largely used is that 
 of Mr. Duff (Fig. 18). This may be made circular 
 or square, but is usually made circular externally, 
 the internal brickwork being so arranged as to give 
 a rectangular combustion chamber. It is cased with 
 iron, and the casing -dips into a water trough on 
 the two sides so as to form a water seal. Across 
 the body of the producer from back to front, and 
 occupying about half the width of the producer, 
 is a ridge of brickwork. On this are fixed 
 vertical iron plates, and above these two sloping grates. 
 The producer is thus divided into two parts, about 
 half the area being occupied by the grates, the other 
 half by the water trough. The air is blown into 
 the space beneath the grate, and passes between the 
 bars into the fuel. The supernatant mass of fuel is 
 thus partly supported on the grate and partly on the 
 mass of ashes resting on the water trough, and as the 
 charge sinks the ashes slip off the bars into the water 
 trough. The producer is very easily cleaned, as the space 
 from whicrj the ashes have to be raked is comparatively 
 narrow. The essential peculiarity of the producer is the 
 arrangement of its bars, and these, as will be seen, differ 
 in function from the bars of an ordinary bar-bottom 
 producer m so far that the ashes are not removed 
 through them, but slide off. This principle can obviously 
 be applied to other forms ot producer. The old type 
 Siemens producer, for instance, can be comparatively 
 easily converted into a producer of the Duff type. 
 
WATER-BOTTOM PRODUCERS. 
 
 75 
 
 The details of water-bottom producers can, of course, 
 be varied indefinitely. In the Swindell producer inclined 
 grates are used, sloping from the sides downwards, but 
 not meeting, so as to leave a central mass of ash which 
 passes down into the water trough, from which it can be 
 drawn as usual. 
 
 In the Thwaite small power producer (Fig. 19) a 
 hanging grate is used, the ashes passing centrally into 
 
 FIG. 19. THE THWAITE SMALL POWER PRODUCER. 
 
 the water trough, the air being supplied into an annular 
 space round the bars. 
 
 The Wilson Water-bottom Producer. The Wilson producer 
 may readily be converted into a water-bottom producer. 
 This is done by Mr. Wilson, as shown in Fig. 20. 
 ^ / Smith and Wincott Producer (Patent 1901, No. 12,895). 
 This is the most recent and one of the best of the water- 
 bottom producers. It is circular, cased with iron, the casing 
 
WATER-BOTTOM PRODUCERS 
 
WATER-BOTTOM PRODUCERS. 
 
 77 
 
78 
 
 AUTOMATIC PRODUCERS. 
 
 being carried down so as to form a water seal in the 
 usual manner. The principal peculiarity is in the way in 
 which the air and steam is supplied to the fuel. This is by 
 a vertical central pipe which is widened out at the top so 
 as to form an inverted cone, which at the top may have a 
 diameter of about 3ft. A series of openings are provided 
 
 FIG. 20. WILSON WATER-BOTTOM GAS PRODUCER. 
 
 all round this by which the air and steam passes into the 
 fuel, and the top is closed by a loosely fitting cap. Owing to 
 the form of these openings there is a very large area 
 for the passage of the air and steam, and these cannot 
 possibly become choked with ash, a great advantage, 
 especially with some classes of fuel. 
 
 -AUTOMATIC PRODUCERS. 
 
 In producers of this type the ashes are removed 
 continuously by means of mechanism, so that hand 
 labour is unnecessary. As the amount of labour 
 required for water-bottom producers is very small, it is 
 doubtful how far the application of mechanism will be 
 economical. The first automatic producer, which, in a 
 sense, was also the first of the water-bottom producers, 
 was that of Mr. Alfred Wilson (see Fig. 22), which has 
 now been in use for many years, and has proved itself 
 to be efficient in practice. 
 
AUTOMATIC PRODUCERS. 
 
 79 
 
 The Wilson Automatic Producer. In some respects this 
 resembles the ordinary Wilson producer, but the air 
 and steam supply is placed at a much higher level, 
 and the spaces each side, instead of being flat-bottomed, 
 are circular in section, and inclined from back to 
 front, so as to make two conical troughs, in each of 
 
 FIG. 22. WILSON AUTOMATIC GAS PRODUCER. 
 
 which works a screw by which the ashes are slowly 
 pushed out. The troughs are kept filled with water, 
 so as to keep the screws cool and protect them from 
 oxidation. The wear and tear is said to be very slight, 
 the screw lasting for years, and the power required to 
 turn it is also small. 
 
 The Taylor Producer. This is an American invention, 
 and the author is not aware that it is in use in this 
 country. The bottom of the producer (Fig. 23) 
 is closed by an iron plate, beneath which is the 
 ashpit, and through the centre of which passes the 
 pipe for supplying the air and steam. The iron 
 
80 
 
 DOWN-DRAUGHT PRODUCERS. 
 
 bottom plate is a little larger than the bottom opening 
 of the producer, and is so placed as to leave an 
 annular space all round. As the ashes accumulate the 
 bottom is rotated, a few turns being given occasionally. 
 
 FIG. 23. TAYLOR PRODUCER. 
 
 This breaks up the cinder and forces some of the ashes 
 over the edge of the plate into the ashpit. A few turns of 
 the bottom at frequent intervals will keep the fuel bed 
 itlways in a solid condition and at the same level. 
 
 DOWN-DRAUGHT PRODUCERS. 
 
 Several attempts have been made to arrange pro- 
 ducers in which the mixture of air and steam is supplied 
 at the top of the gasifying chamber and the gas drawn off 
 from the bottom, the idea apparently being that the tarry 
 matters would be more completely destroyed. (See 
 
DOWN-DRAUGHT PRODUCERS. 
 
 81 
 
 Chapter IX.) Such producers have not come largely into 
 use, and are subject to very serious defects, and especially 
 to great difficulty in the removal of the ash. 
 
 The first of these, that of Mr. Howson, was simply a 
 solid-bottom producer, with apertures in the floor for the 
 escape of the gas and doors for the withdrawal of the ash, 
 the fuel being charged, as usual, at the top, and the air 
 and steam being supplied from a series of ports near the 
 top. 
 
 Korting's Producer. This producer is a bar-bottom down- 
 draught producer. It is made in several forms to deal 
 with variations in the quality of the fuel available ; but 
 that designed for use with bituminous coal, which is 
 shown in Fig. 23A, will illustrate the principle on which 
 
 FIG. 23A. KORTING'S GAS PRODUCES. 
 
 it works. The producer is provided with a series of 
 horizontal firebars on which the fuel rests, and with two 
 vertical grates, C and C 1 , in this case on opposite sides 
 of the producer, one near the bottom, the other near the 
 top, each provided with its own air main F F 1 . The 
 fuel is supplied, as usual, from the hopper B, and the air 
 and steam passing in from the grates causes gasification. 
 A passage N is provided so that the gas produced in the- 
 upper part of the producer may find its way to the lower 
 part without passing through the fuel. The gas is drawn 
 off through the grate L to the main M. Ashes can be 
 
82 
 
 DOWN-DRAUGHT PRODUCERS. 
 
 removed through the door G. The vertical grates may 
 be on the same or on opposite side of the producer. 
 
 The producers described are, of course, but a few 
 selected from the innumerable forms which have been 
 described and patented. They are, however, typical, 
 and the author does not think he has omitted any 
 distinct types, though, obviously, details may be varied 
 to almost any extent. 
 
 THE BLAST FURNACE AS A GAS PRODUCER. 
 
 An enormous amount of combustible gas is made in 
 the blast furnaces used for smelting iron. As this gas is 
 a by-product, the blast furnace should hardly be classed 
 as a gas producer in the sense in which gas producers 
 are considered here, but as the gas from it is very largely 
 used for steam raising, furnace firing, and driving gas 
 engines it deserves a brief consideration. 
 
 At the tuyeres, in presence of a large excess of carbon 
 and at a very high temperature, which necessarily exists 
 in such a furnace, all the oxygen of the air is combined 
 to carbon monoxide, and, as the only moisture carried 
 in is that of the air, the amount of hydrogen in the 
 gas is very small. 
 
 As the gas reaches the upper part of the furnace, 
 carbon monoxide is added to it from the reduction of the 
 carbon dioxide of the limestone by the hot carbon, and 
 at the same time carbon dioxide is formed by the action 
 of the carbon monoxide on the oxide of iron ; thus the 
 gas will be some what poorer in carbon monoxide and much 
 poorer in hydrogen than producer gas made from coke 
 with the aid of steam. When raw coal is used in the 
 blast furnace the gas distilled from it will of course mix 
 with the carbon monoxide, carbon dioxide, and nitrogen. 
 The following analysis by volume will indicate the nature 
 of the gas from a coke-fed blast furnace. 
 
 
 (i) 
 
 (2) 
 
 (3) 
 
 Carbon monoxide 
 
 28-80 
 
 29-50 
 
 28-10 
 
 Carbon dioxide 
 Nitrogen 
 
 12-90 
 57-60 
 
 9-00 
 60-00 
 
 10-00 
 61-00 
 
 Hydrogen 
 
 0-70 
 
 1-50 
 
 0-90 
 
 
 
 
 
 From a coal-fed furnace the amount of hydrocarbons 
 will be much larger. For example : 
 
BLAST-FURNACE PRODUCERS. 
 
 83 
 
 
 (l) 
 
 (2) 
 
 (3) 
 
 (4) 
 
 Carbon dioxide ... 
 
 8-57 
 
 8-61 
 
 5-40 
 
 6-79 
 
 Carbon monoxide. . . 
 
 27-15 
 
 28-06 
 
 30-10 
 
 26-40 
 
 Hydrogen 
 
 5-48 
 
 5-45 
 
 6-26 
 
 12-23 
 
 Marsh gas 
 
 4-27 
 
 4-37 
 
 3-20 
 
 71 
 
 Nitrogen 
 
 54-29 
 
 53-38 
 
 55-10 
 
 58-81 
 
 It will be seen, therefore, that the gas from a coal-fed 
 furnace is little inferior to ordinary, and better than some 
 varieties of producer gas. The blast furnace, taking into 
 account the other work which it has to do, is probably the 
 most perfect gas producing machine in existence. The 
 column of material is so high that cooling is very perfect, 
 and would be much more so if it were not for the 
 reduction of the oxide of iron which takes place near the 
 top of the furnace, and owing to the depth of the column 
 of material and the high temperature the reduction of 
 carbon dioxide to carbon monoxide is perfect, and as the 
 slag is tapped in a liquid condition there can be no loss 
 of unconsumed carbon. 
 
 It has been suggested to model gas producers on the 
 lines of the blast furnaces, adding a little limestone to flux 
 away the ash of the coke, and where a sufficiently large 
 quantity of gas is required such a type of producer would 
 probably be very efficient. Steam could be used as in 
 ordinary producers, but only in limited quantity. The 
 high initial cost would be the chief drawback to a 
 producer of this type. 
 
 An ordinary Scotch blast furnace will gasify about 
 550 tons of coal a week, or something over three tons an 
 hour, the diameter of the hearth being but little larger 
 than an ordinary gas producer, whilst a modern Cleveland 
 furnace will gasify about 1,500 tons of coke per week, or 
 nearly nine tons an hour. 
 
 The Thwaite Rapid Cupola Producer. Mr. B. H. Thwaite 
 has recently designed a producer of the blast-furnace 
 type, which is the first attempt to apply what many have 
 long thought to be the correct principle to practice, and 
 a large installation is at present in course of erection. 
 
 The essential differences between this and the ordinary 
 type of producer are (1) that air is supplied at a high 
 pressure, (2) no steam is used, (3) the temperature is 
 sufficiently high to fuse the slag, suitable fluxes being 
 added when necessary. 
 
 OF 
 
84 
 
 BLAST-FURNACE PRODUCERS. 
 
 The generator is very like a cupola furnace, about 
 30ft. high and about 6ft. internal diameter. The air is 
 supplied a little above the bottom by a series of horizontal 
 tuyeres at a pressure of about 21bs. or 31bs. on the square 
 inch, though any convenient pressure can be used. 
 
 The gas, which leaves the producer at a low tempera- 
 ture, is forced through a "hydraulic head" to separate 
 the tar, then through suitable washers if necessary to 
 a gas holder. The bottom of the producer is so shaped 
 that the liquid slag can be tapped off through a tap hole. 
 
 3.46 -' 
 
 FIG. 23B. THWAITE'S GAS PBODUCEK FOB MOTIVE POWEB. 
 
 A is the gas producer, which is supplied with fuel by the elevator B. C is a 
 sciubber or rough filter, and D is a tubular recuperator in which the gas is cooled 
 and the air for combustion is warmed. From this the gas passes to the purifier H, 
 and thence to the gas holder I. 
 
 The gas is good and of very uniform quality, and owing 
 to the thorough absorption of heat by the mass of fuel in 
 the upper part of the stack the loss of heat is small, and 
 the producer has a very large gasifying capacity. Very 
 little labour is needed, the combustion is complete, and 
 the slag is very easily removed. Automatic charging is 
 easily applied, the fuel being lifted by means of an endless 
 
BLAST-FURNACE PRODUCERS. 
 
 85 
 
 belt lifter and deposited in the charging hopper. The 
 slag is easily converted into a perfectly white slag wool, 
 for which there is a considerable demand. 
 
 The following analyses are of gas made in a producer 
 of this type : 
 
 
 i. 
 
 
 2. 
 
 
 3. 
 
 
 Carbon monoxide 
 Marsh gas 
 Hydrogen 
 Total combustible 
 
 Nitrogen 
 Carbon dioxide . . 
 Non- combustible 
 
 29-50 
 1-56 
 3-80 
 
 63-47 
 1-67 
 
 
 27-0 
 1-9 
 5-5 
 
 61-4 
 4-2 
 
 
 25-24 
 1-79 
 
 . 7-50 
 
 61-55 
 3-92 
 
 
 34-86 
 
 34-4 
 
 34-53 
 
 65-14 
 
 65-6 
 
 65-47 
 
 100-00 
 
 100-00 
 
 100-00 
 
 100-00 
 
 100-00 
 
 100-00 
 
CHAPTEK VII. 
 
 ; 
 
 MOND GAS. THE PRODUCER. THE CONDENSING 
 PLANT. THE PRODUCTS. COST OF WORKING. 
 
 As has already been pointed out, if a very large 
 excess of steam be blown into a gas producer, a great 
 deal of it will pass through undecomposed. At the 
 same time this will lead to a considerable modification in 
 the reactions taking place. The amount of steam 
 decomposed will be very large, so that the quantity of 
 hydrogen in the gas will be much larger than in ordinary 
 cases, sometimes rising above 25 per cent, by volume ; at 
 the same time the temperature will be much reduced, and 
 from one-half to two-thirds of the carbon will be oxidised 
 to carbon-dioxide. Such a gas will therefore be very 
 different in character from ordinary producer gas, and 
 must be judged by different standards. It is largely a 
 hydrogen and not a carbon monoxide gas. It is not likely 
 such a gas would ever have been made commercially if 
 the process had been considered only from the standpoint 
 of gas production, but the alteration in the method 
 of working brings with it another important change. 
 In an ordinary producer fed with coal comparatively 
 little of the nitrogen escapes in the form of ammonia, 
 especially if the top of the producer be hot, but in 
 presence of a large amount of steam and free hydrogen, 
 and at the necessarily lower temperature of a producer 
 blown with a large excess of steam up to 70 per cent, of the 
 nitrogen in the fuel can be obtained in the form of ammonia, 
 and thus, though the process is more costly, the extra cost 
 may be more than paid for by the large amount of 
 ammonia obtained. 
 
 Mr. Beilby some years ago erected a plant at the Oak 
 Bank Oil Works for the preparation of gas and recovery 
 of ammonia, a large excess of steam being used. The 
 method used was based on the principle adopted by 
 Messrs. Young & Beilby in their retorts for the distilla- 
 tion of shale and recovery of the ammonia. The plant is 
 thus described in Mills & Kowans' fuel, p. 276 : " A 
 number of vertical retorts are grouped together in a bench 
 or double row, with passages surrounding them for the 
 circulation of the heating gases." These are built of 
 brick, and " have the exit pipe for the gases at about the 
 
MOND GAS. 87 
 
 middle of their height. The coal is fed in from hoppers 
 at the top, and is distilled at a good heat in the upper 
 part of the retorts. The tar vapours, together with the 
 steam, pass down through the hot coke, and are decom- 
 posed into permanent gases and ammonia, no tar being 
 found in the pipes when the temperature is properly 
 regulated. The coke passing into the lower half of the 
 retorts is burnt in a mixture of steam and air, with excess 
 of steam in order to secure the ammonia, and the gases 
 from this portion ascend and pass away by the exit pipe. 
 In starting these retorts it is necessary to obtain some 
 gas for combustion in the chambers surrounding them in 
 order to heat them up. This may be made from coke in 
 a subsidiary producer placed alongside. The gases from 
 the retorts are drawn away by the main, and are passed 
 through condensers and scrubbers, when the ammonia is 
 separated and recovered." About 75 per cent, of the 
 nitrogen in the fuel is recovered as ammonia. 
 
 Mond's Process. Dr. Ludwig Mond commenced experi- 
 menting with gas plant about 1879, and in his presidential 
 address to the Society of Chemical Industry in 1889 he 
 pointed out what had been done in the direction of 
 recovering ammonia from the products of the gasification 
 of coal, and gave drawings of a gas producer and con- 
 densing plant he had devised, and with which he had 
 obtained good results. The plant now used is a modifica- 
 tion and improvement of that there described, but the 
 principle is exactly the same. The plant and method of 
 working will be slightly modified according to whether 
 the main object is the production of gas or the recovery of 
 ammonia. It was principally with a view to the ammonia 
 recovery that the process was devised. 
 
 The Plant. The plant consists essentially of two parts, 
 the gas producer and the condensing and recovery plant. 
 
 The Producer. The producer now used is of the 
 water-bottom type, and consists of a double-cylindrical 
 wrought-iron shell, lined with firebrick up to near the 
 top as usual. The bottom of the producer is narrowed, 
 and terminates in an iron ring, on which hang the fire- 
 bars which form a continuation of the producer, and 
 being attached at the bottom to another iron ring form a 
 hanging grate, through the centre of which the ashes 
 pass out into the water trough. The outer shell of the 
 producer is prolonged downwards into the trough of 
 water so as to form a water seal, and the ashes are 
 
88 MOND GAS. 
 
 drawn from beneath this by means of spades and rakes 
 in the usual way. In the centre of the top of the 
 producer is the charging hopper, to which is attached a 
 bell, which extends some distance into the producer, and 
 which is always surrounded by hot gas when the producer 
 
 FIG. 24. MOND PRODUCER. 
 
 is at work. Steam and air are supplied into the space 
 between the two casings of the producer, and passing 
 downwards are delivered in a ring outside the grate, and 
 thence pass into the mass of fuel, the gas being drawn off 
 near the top of the producer as usual. 
 
MOND GAS. 89 
 
 The Condensing Plant. One characteristic of the Mond 
 plant is its condensing plant. This is essential even if it 
 be not desired to recover the by-products, on account 
 of the large quantity of steam used, and the necessity for 
 condensing the undecomposed excess. 
 
 The ordinary plant consists of three portions, the 
 regenerators, the washer, and the towers. 
 
 The regenerators are a series of double wrought-iron 
 tubes united alternately at bottom and top. The hot gas 
 from the producer passes through the inner tubes, up and 
 down, and the mixture of steam and air for supplying the 
 producer passes in the opposite direction through the 
 annular space between the inner and outer tubes, thus 
 surrounding the hot gas, and as the gas is cooled the air 
 and steam mixture is heated. 
 
 The washer to which the gas next passes is a large 
 wrought-iron chamber partly filled with water &nd 
 provided with mechanical dashers fixed along the surface 
 of the water in such a way that as they rotate the blades 
 throw up a large quantity of spray which fills the 
 chamber. The gas is thus cooled to about 90, and the 
 water vapour formed is swept forward, so that there is 
 no condensation of ammonia liquor. 
 
 Three towers are used, called respectively the ammonia 
 recovery or acid tower, the gas-cooling tower, and the air 
 heating and saturating tower. 
 
 The gas passes first to the acid tower, entering at the 
 bottom and passing upwards. The tower is filled with a 
 checker-work of firebrick, so as to give a large surface of 
 contact, and a rain of sulphuric acid liquor is allowed to 
 fall down it, which, meeting the free ammonia in the 
 ascending gases, converts it into sulphate. The acid 
 liquor contains only about 4 per cent, of free acid, and is 
 circulated continuously by means of a pump, its strength 
 being maintained uniform by drawing off the sulphate 
 liquor and adding a corresponding amount of fresh acid. 
 The liquor and acid is passed through a settling tank, so 
 as to be thoroughly mixed before it reaches the pump. 
 
 The gas from the acid tower, deprived of its ammonia, 
 passes from the top of the tower into a large wrought- 
 iron vessel, 12ft. diam., filled with wood packing so 
 arranged as to give a large surface. The gas containing 
 its burden of steam has here to meet a downward current 
 of cold water, which considerably reduces its temperature. 
 
90 MOND GAS. 
 
 "When entering the gas-cooling tower it (the gas) is 
 nearly saturated with steam, so that as its temperature 
 begins to fall its capacity for carrying steam rapidly 
 diminishes, and condensation takes place. The table 
 (Appendix 1) shows how considerable the condensation 
 must be, and the result is the utilisation of the latent 
 heat of the steam, as well as the sensible heat of the 
 steam and gas, in raising the temperature of the circu- 
 lating water, which consequently escapes hot."* 
 
 " From the gas-cooling tow r er the gas is conveyed by 
 the gas mains to the furnaces for combustion for use in 
 gas engines. In the works at North wich more than 
 24,000,000 cub. ft. of gas are used daily." The hot water 
 which leaves this tower is pumped to the top of the 
 heating and saturating tower, where its heat is given 
 back to the cold air passing through on its way to feed 
 the producer, and it is at the same time saturated with 
 water vapour. The air is forced through the apparatus 
 and to the producer by suitable blowers. 
 
 The Steam. The amount of steam used is about 
 2J- tons per ton of fuel consumed. As a ton of carbon 
 could only decompose 1| tons of water even if it were 
 completely oxidised by steam, and as the fuel will 
 probably not contain more than 60 per cent, of carbon, 
 a considerable quantity of which will be burnt by air, 
 by far the greater portion of the steam will pass through 
 undecomposed ; probably, at least, two tons so passing. 
 Hence the necessity for the elaborate condensing plant. 
 
 The Products. Owing to the low temperature of the 
 producer and the large excess of steam, the gas is very 
 unlike ordinary producer gas. The percentage of carbon- 
 dioxide and of hydrogen is high, and that of carbon- 
 monoxide is low. 
 
 The following analysis shows the composition of the gas : 
 
 
 By Volume. 
 
 By Weight. 
 
 Carbon-monoxide 
 
 iro 
 
 13'1 
 
 Carbon-dioxide 
 
 17-1 
 
 32-0 
 
 IVEarsh Sfas 
 
 rs 
 
 1'2 
 
 Olefines 
 
 4 
 
 5 
 
 Hydrogen . . 
 
 27 '2 
 
 2-2 
 
 Nitrogen 
 
 42-5 
 
 51-0 
 
 
 100-0 
 
 100-0 
 
 * Humphrey's, Proc. Inst. Civ. Eng. cxxix., pt. 3. 
 
MOND GAS. 91 
 
 The calorific power of such a gas will be 
 
 Carbon monoxide... '131 X 2400=314 C 11= 565B.T.U. 
 
 Marsh gas '012x12000=144 ,,= 259 
 
 Olefines (Qe C n H 2n ) '005x10000= 50 = 90 
 Hydrogen '022x29300=644 ,,=1159 
 
 1152 2073 
 
 and as 1000 cub. ft. weighs about 65'681bs., 1000 cub. ft. 
 will give 75,663 CU of heat=136,193 B.T.U. 
 
 The loss of heat in the producer is about 20 per cent., 
 so that the heating power of the gas is about 80 per 
 cent, of that of the fuel consumed. 
 
 The gas is free from tar and excess of moisture, burns 
 with a non-luminous flame, and has been successfully 
 used for most purposes for which fuel gas is required, 
 including steel melting. 
 
 Ammonia. The ammonia recovered is equal to about 
 90 Ibs. of sulphate for each ton of coal consumed, or one 
 ton of sulphate for each 23 tons of coal. 
 
 As a rule, of course, Mond gas will be made chiefly 
 for the purpose of recovering the by-products, in which 
 case about 2J tons of steam will be used per ton of fuel, 
 but a similar gas can be made without by-product 
 recovery, in which case only about half this amount of 
 steam need be used. 
 
 In a paper read before the Institute of Civil Engineers, 
 Mr. Humphreys gave a detailed account of experiments in 
 connection with the working of a Mond gas plant. Those 
 interested should refer to the paper. 
 
 STATEMENT OF COST OF WQEKING A MOND PEODUCEE 
 
 AND KECOVEEY PL ANT. t 
 (At Winnington, Cheshire.) 
 
 Price of coal per ton at works... ... ... 6 2 
 
 Selling price of sulphate. Price, August, 
 
 1896, net naked at works per ton 7 4 6 
 
 1 ton of sulphate is obtained from 23 tons of fuel 
 
 gasified, but adding fuel for steam required the total is 
 
 28-56 tons. 
 
 Cost per ton of sulphate of ammonia made 
 
 Total cost of all fuel (28'56 tons at 6/2) ... 8 16 1 
 Wages at producers (23 tons at 6'4d.) 12 3 
 
 J Humphreys. 
 
92 MOND GAS. 
 
 Manufacturing, wages, administration 19 
 
 Manufacturing, wages, labour 19 8 
 
 Repair wages and materials, including 
 
 renewals 18 3 
 
 Lubricants 1 8 
 
 Gas for lighting purposes 311 
 
 Sulphuric acid 0'95 tons at 145Tw 1 4 4 
 
 Total for above 12 17 11 
 
 Selling price of sulphate naked at works ... 7 4 6 
 
 Final cost of 23 tons of fuel gasified 5 13 5 
 
 or final cost of gas from 1 ton fuel gasified 4 11 
 
 or cost of 1,000 cubic feet of gas (at 15 C) 0'351d. 
 
 or gas for 1 h.p. will cost '02685d. 
 
 or gas for Ih. p. for 24 hours a day for a year 19 7'2 
 
 The Duff Plant. It will be evident that gas could be 
 made with other types of producer, but the only one 
 which seems to have been actually used in this way is 
 the "Duff," an installation of which, put up by the 
 United Alkali Company, at Fleetwood, has been running 
 since the spring of 1899, gasifying 500 tons of slack per 
 week without a stop or hitch of any kind, except a slight 
 overhaul after twelve months' working. 
 
 The producers used are rectangular, and the slack is 
 distributed mechanically into large hoppers placed directly 
 above the charging hoppers of the gas producers. 
 
 The gas, as it leaves the producer, enters the recuperators 
 or superheaters, which are narrow rectangular tanks 
 or chambers with partitions to direct the passage of the 
 air and steam on its way to the producers. These 
 chambers contain zig-zag vertical pipes which convey 
 the hot gases from the producer on their way to the 
 washing plant. The gas then passes to the washing 
 tower, where it meets a stream of descending sulphuric 
 acid ; then to a cooling tower, in which the gas is cooled 
 before passing to the engines ; and beyond this is a third 
 tower where the incoming air meets the hot water from 
 the cooling tower, and this becomes heated and charged 
 with water vapour." 
 
 It will be seen that the condensing plant closely 
 resembles that used in the Mond process. 
 
 Quite apart from the recovery of by-products, the gas 
 made with excess of steam, which we may call Mond 
 gas, seems to have advantages over ordinary producer gas 
 
MOND GAS. 93 
 
 for gas engines, and some other purposes. Such a gas 
 may be made in any type of producer by using a large 
 excess of steam, and if the ammonia is not to be recovered 
 the excess of steam need not be so large as that used by 
 Mr. Mond, probably one ton for each ton of coal burnt 
 will be sufficient, and much less elaborate condensing 
 plant will be necessary. 
 
CHAPTER VIII. 
 
 WATER GAS. THE LEEDS PLANT. THE LOOMIS PLANT. 
 THE DELLWIK-FLEISCHER PROCESS. PROPERTIES OF 
 WATER GAS. 
 
 As has been already pointed out, when steam is passed 
 over red hot coke it is decomposed, and- a mixture of 
 carbon monoxide and hydrogen is producd thus 
 
 C + H 2 = CO+2H. 
 
 This reaction, as will be seen, is made up of two parts, 
 the decomposition of a molecule of water which will 
 absorb heat, and the formation of a molecule of carbon 
 monoxide which will evolve heat. The thermal result 
 will be, starting from liquid water 
 Heat of formation of one molecule of carbon 
 
 monoxide 29000 + 
 
 Heat of decomposition of one molecule of water 68360 
 
 Balance ... ... 39360- 
 
 If, however, as will actually be the case in practice, 
 steam be used, the latent heat of steam must be deducted 
 from the figure given for the calorific power of hydrogen. 
 The figures will then be 
 Heat of decomposition of one mole- 
 cule of water 68360 
 
 Latent heat of steam, 537 x 18 ... 9666 
 
 Heat of decomposition of steam ... ... 58694 
 
 Heat of formation of one molecule of carbon 
 
 monoxide . 29000 + 
 
 29694 
 
 If the reaction is to go on, this 29694 units of heat 
 must be supplied from outside. 
 
 It will be seen, therefore, that such a process must 
 either be worked intermittently, or else heat must be 
 supplied by the combustion of fuel in some other way. 
 The intermittent method of working has been almost 
 
96 WATER GAS. 
 
 universally used. Air is first blown over hot coke till 
 the mass becomes very hot, the reaction being 
 C + O = CO, by which 29,000 C units of heat are 
 evolved for each 12 parts of carbon consumed. Steam is 
 then blown over the hot coke, water gas being produced 
 till the mass is so far cooled that the decomposition does 
 not take place readily. The steam is then shut off, 
 and air sent in till the coke is once more hot, and so on. 
 
 Theoretically the gas should contain equal volumes 
 of carbon monoxide and hydrogen, so that its composition 
 would be : 
 
 
 By Volume. 
 
 By Weight. 
 
 Carbon monoxide ... 
 
 50 
 
 93-33 
 
 Hydrogen . ... ... 
 
 50 
 
 6-67 
 
 
 
 
 
 100 
 
 100-00 
 
 Owing to the conditions of production, however, small 
 quantities of nitrogen and carbon dioxide are always 
 present. 
 
 The idea of the manufacture of such gas must have 
 occurred to makers of producer gas, and it is impossible 
 to say by whom it was first put into practice, but 
 a plant for the production of water gas is said to have 
 existed at Phenixville, Pa., in 1874. A patent was 
 granted to J. S. C. Lowe in 1875, and in 1886 the 
 committee of the Franklin Institute awarded a medal of 
 honour to Mr. Lowe for his pioneering work. 
 
 Little was heard in this country of water gas as 
 distinguished of course from the gas made in producers 
 into which steam was blown at the same time as air, till 
 the formation of the British Water Gas Syndicate and 
 the erection of the plant of Mr. Samson Fox at the 
 Leeds Forge in 1888. 
 
 The Leeds Forge Plant. As this plant may be regarded 
 as being the pioneer British plant, it will be taken 
 as a type of the class of apparatus to which it 
 belongs. " The generator consists of a cylindrical 
 vessel of boiler-plate lined with firebrick. The bottom 
 of the generator is somewhat narrowed, and the fuel 
 
WATER GAS. 97 
 
 falls on to the bottom in a cone, leaving an annulus 
 round which alternately the air passes to the fuel, 
 and the gas escapes from the fuel. Connected with 
 this annulus through a port or passage formed in the 
 brickwork is the valve chamber, which is kept cool by 
 circulating water, and is provided with three passages, 
 
 FIG. 26. WATER-GAS PLANT AT THE LEEDS FORGE. 
 
 through one of which the air passes, and through another 
 the gas escapes, the centre passage being in connection 
 with the generator. The valve slides on the face of this 
 box, and has a double U-shaped port which may be brought 
 into alternate connection with either the air or gas 
 passage and the centre passage." 
 
98 WATER GAS. 
 
 The air enters from the main under suitable pressure, 
 being regulated by the valve, and the gas main conducts 
 the water gas through a scrubber to the gas holder. 
 
 From the upper part of the producer a producer gas 
 main leads to the furnaces or other appliances where the 
 producer gas is to be burned, and a pipe from a boiler 
 leads a supply of steam to the upper part of the producer 
 above the level of the fuel. 
 
 The working is intermittent, coke or anthracite is 
 charged by the hopper, the producer being kept full. Air 
 is blown in from the air main, combustion takes place, 
 and a gas, which is a simple producer gas, consisting 
 almost entirely of carbon monoxide and nitrogen, passes 
 away by the producer gas main. As the combustion of 
 the coke evolves heat, the temperature rapidly rises. As 
 soon as the charge is hot enough the air is shut off, and 
 the producer gas valve is closed and the steam valve 
 and the water gas valves are opened. 
 
 The steam passing through tke coke is decomposed, 
 and water gas is formed. This goes on till the coke is 
 sufficiently cooled, when the current is again reversed. 
 
 In the plant at the Leeds Forge, gas was made for 
 4 mins., and the heating up occupied 10 mins. Clinker 
 was cleaned out every six hours through doors at the 
 bottom of the generator, the process occupying about 
 8 mins. 
 
 The average yield of water gas from common gas coke 
 is about 34,000 cub. ft. to the ton, and the production of 
 each generator in use at the Leeds Forge was 2,200 cub. ft. 
 per hour, or 52,800 cub. ft. per day, the cost of gas being 
 under 4d. per 1,000 cub. ft., including fuel, water, wages, 
 superintendence, depreciation, and interest. Each cubic 
 foot of water produces 2,250 cub. ft. of gas, or one ton of 
 water (which in Leeds costs 1 Jd.) will produce 84,000 cub. 
 ft. of gas. 
 
 The amount of producer gas made is very large. Mr. 
 Fox stated that three-quarters of the fuel was used in heat- 
 ing up i.e., in the production of producer gas each 
 ton of coke yielding 34,000 cub. ft. of water gas and 
 140,000 cub. ft. of producer gas, so that unless use can 
 be made of the producer gas the process is not likely to 
 be economical. 
 
WATER GAS. 99 
 
 If the producer gas formed in the heating-up stage 
 is not to be used for fuel it can be used to heat the steam 
 (so as to lengthen the time occupied in gas production), 
 to raise the necessary steam, or in some other way. 
 
 In Germany very similar plant was erected in 
 
 1885. 
 
 The Lowe Producer. The producer described above is 
 essentially that of Lowe, but the Lowe process as 
 developed in America has been modified, and has been 
 largely used for producing a lighting gas, for which purpose 
 the water gas must be enriched with petroleum or some 
 similar hydrocarbon, since water gas itself burns with a 
 non-luminous flame. 
 
 The apparatus consists of two parts a producer and 
 a regenerator the latter being a circular chamber lined 
 with firebrick and filled with a chequer-work of firebrick. 
 The producer gas formed during the heating up is passed 
 into the regenerator and there burnt, thus heating the 
 brickwork to a very high temperature. When the 
 heating up is finished, steam is put on in the usual way. 
 At the top of the regenerator the water gas is made to 
 meet a fine spray of petroleum, which is at once volatilised, 
 and, passing over the hot brick work in the regenerator, is 
 decomposed into permanent gases, which pass through 
 the scrubber to the gasholder. The process is worked 
 intermittently, as in the Leeds plant. 
 
 The Loomis Plant. The producer used in this apparatus 
 consists of a cylindrical casing lined with firebrick, 
 about 12ft. by 9ft. At the top is a charging hopper, 
 as usual, and at the bottom a firebrick grate over an 
 ashpit. As originally described, the ashpit was divided 
 by fireclay slabs. Air was drawn down through a series 
 of ports, and the hot producer gas heated the fire- 
 clay slabs under the grate to a very high temperature. 
 When heating up was complete steam was blown into the 
 ashpit, being there intensely heated by passing over the 
 fireclay slabs, and passed up through the hot coke, 
 producing water gas. 
 
 Mr. Loomis gave the following estimate of gas produc- 
 tion in his producer per 1,000,000 cub. ft., the coal costing 
 about $3 a ton. 
 
100 WATER GAS. 
 
 Coal 25 tons 75 
 
 Coal for steam- 3 tons ... ... ... 9 
 
 Labour 22 
 
 Supplies and repairs ... ... ... 4 
 
 Purifying ... ... ... ... ... 5 
 
 115 
 
 Received for producer gas ... ... 44 
 
 75 
 Interest and depreciation... ... ... 25 
 
 S100 
 
 Or cost per 1,000 cub. ft., $0-10, or say 5d. ; or if the 
 producer gas be lost, $0'14, say 7d. 
 
 In the newer plants erected by the Loomis-Pettibone 
 Company the arrangement is a little different. Two 
 producers similar to that described above, except that 
 there are no fireclay slabs in the ashpit, are worked 
 together and are attached to a vertical boiler provided 
 with suitable valves. 
 
 " In starting fires, a layer of coal or coke about 5ft 
 in depth is put on and ignited at the top, an exhauster 
 creating a downward draught. When the body of the 
 fuel is ignited coal is frequently charged, raising the fuel 
 bed to about 8ft. above the grates, at which height it is 
 maintained. Bituminous coal is generally used, and is 
 charged at intervals as needed through, the feed door at 
 the top of the generator." 
 
 Air is also admitted by the same door, and by means 
 of an exhauster is drawn down through the fresh charge 
 of coal and through the hot bed of fuel beneath. The 
 resultant producer or generator gas is drawn through the 
 grates and ashpits of generators Nos. 1 and 2, the valves 
 A and B, up through the vertical boiler to the scrubber 
 and exhauster, through the valve C, and is delivered into 
 a small gasholder for supply to the furnaces. When the 
 exhauster has brought the fuel up to incandescence the 
 charging doors E F are closed, valve B lowered, the valve C 
 closed, and the valve D leading to the water gasholder 
 opened. Steam is then turned on into the ashpit of 
 generator 2, and in passing through the incandescent coal 
 is decomposed, forming water gas. From generator 2 the 
 
To x/?aas fer a/xt 
 To Producer Gas S/o/afes 
 
 -Jo Lxfrousrer as>c/ Proc/vcer 
 ~ Cos Ho/off r 
 
 FIG. 27. LOOMIS-PETTIBONE WATEB-GAS PLANT. 
 
102 WATER GAS. 
 
 gas passes through the connecting pipe shown near the 
 top of the generator and down through producer No. 1, 
 through valve A into and up through the boiler, away by 
 valve D, and then, after being washed in a scrubbier, is 
 conducted into a holder. 
 
 Water gas is made for 5 mins., when the temperature 
 of the fuel beds having been considerably reduced the 
 steam is shut off, and air is admitted. In starting the 
 next run of water gas, the steam is sent into the bottom 
 of generator 1. 
 
 It will be seen that in this method of working, though 
 coal is or may be used, the tarry matter will be com- 
 pletely broken up by passing through the thick layer of 
 hot fuel, and the steam is very completely decomposed ; 
 also the sensible heat of the gases is to a large extent used 
 in raising steam. 
 
 The producer and water gas are sent to separate gas- 
 holders, but may be mixed in one holder should it be 
 thought to be desirable, or they may be used from the 
 holders in any suitable proportion. 
 
 The Dcllwik-Flcischcr Plant. It will be seen that all the 
 forms of plant described indeed all in use until the 
 introduction of the Dellwik-Fleischer plant labour under 
 the disadvantage that during the heating-up stage a large 
 quantity of producer gas is made, because under the 
 conditions which hold in the producers it is impossible 
 to oxidise the carbon more completely than to carbon 
 monoxide. Thus but little heat is evolved in the producer, 
 and a combustible gas escapes. " If the carbon could be 
 burnt to carbon dioxide, the whole of the available heat 
 of combustion would be evolved in the producer, thus the 
 heating-up stage could be very much shortened, and no 
 producer gas would be made. Messrs. Dellwik & Fleischer 
 have succeeded in doing this, and their plant, therefore, 
 marks an enormous forward step in the production of 
 water gas indeed, makes it possible to make and use 
 water gas economically where there is no demand for 
 producer gas, which is hardly possible with any of the 
 older types of plant. 
 
 The essential difference between the plant of Messrs. 
 Dellwik and Fleischer and the earlier types is that while in 
 the latter the fuel bed was made so thick, and the quantity 
 of air supplied was so small that the carbon dioxide 
 
WATER GAS. 
 
 103 
 
 formed at first was almost completely decomposed by the 
 hot carbon, as in ordinary gas producers, in the former the 
 bed of fuel is made so thin, and the air is supplied in such 
 quantity that the carbon is completely burnt to carbon 
 dioxide. 
 
 The results which are obtained by this change are 
 described in the following extract and accompanying 
 table from Mr. Dellwik's paper, read before the Iron and 
 Steel Institute in 1900.* 
 
 The chemistry of the process is, of course, exactly the 
 same as that of the other processes. It is described as 
 follows by Mr. Dellwik : 
 
 " If we look into the chemical reaction in the forma- 
 tion of water gas, we find that 181bs. of steam, consisting 
 of 21bs. of hydrogen and 161bs. of oxygen, require for 
 their decomposition 2x28,780=57,560 thermal units. 
 The 161bs. of oxygen combines with 121bs. of carbon to 
 281bs. of carbon monoxide, which in mixture with the 21bs. 
 of hydrogen form 301bs. == 753-4 cub. ft. of water gas. 
 The heat developed by the formation of the carbon 
 monoxide is 12 x 2,400 = 28,800 thermal units, thus 
 leaving a balance of 57,560-28,800=28,760 thermal 
 units, which must be replaced by the combustion of 
 carbon during the blows. Assuming, then, as is approxi- 
 mately the case in practice, that the blow gas leaves the 
 generator at a temperature of 700 C., we find 
 
 lib. C requires for 
 combustion .... 
 
 The O is accom- 
 panied by .... 
 
 and the products of 
 
 - combustion carry 
 with them at 
 700 C 
 
 The heat of com- 
 bustion of lib. 
 Cis . 
 
 Old Method. 
 to CO 1| Ibs. 
 
 4-321bs. N 
 
 1,136 Th.U. 
 
 2,400 Th.U. 
 
 Dellwik Method. 
 32 
 
 12 
 
 to C0 2 ?? Ibs. O 
 
 Balance available ) oinn 1 1 QA 
 
 i, i- .LI. r 24:00 l.lob 
 
 for heating the \- i O<M ! 
 
 i ( = 1,264 units, 
 
 fuel is ) 
 
 8-641bs. N 
 
 2,092 Th.U. 
 
 8,080 Th.U. 
 
 8,080-2,092 
 = 5,988 units. 
 
 * " Journal Iron and Steel Institute," Vol. i., 1900, p. 123. 
 
104 
 
 WATER GAS. 
 
 To fill the before- 
 mentioned 
 balance of 
 28,760 Th.U.* 
 the production of 
 301bs. of gas, 
 there must be 
 burnt 
 
 Not counting the "] 
 heat lost by radi- 
 ation and other 
 causes, there are 
 required for 
 the production 
 of 301bs. = 753 
 cub. ft. of water 
 gas or per lib. of 1 
 L.j 
 
 Old Method. 
 
 28,760 
 
 1,264 
 22-751bs. C. 
 
 Dellwik Method. 
 
 28,760 
 5,988 
 = 4-831bs. C. 
 
 C are obtained. 
 
 12 + 22-75 
 = 34-751bs. C. 
 
 21-7 cub. ft. 
 of water gas. 
 
 12 + 4-83 
 = 16-831bs. C. 
 
 44-7 cub. ft. 
 of gas. 
 
 As water gas of 
 theoretical com- 
 position contains 
 
 167 Th.U. per 3,627 Th.U. 7,465 Th.U. 
 
 cubic foot, there J- = 44-8 per cent. . . = 92'5 per cent, 
 are utilised in of the heating of the heating 
 
 the water gas value of the C. value of the C. 
 
 from lib. of 
 carbon 
 
 The difference between the two processes will be 
 obvious. Indeed, it has long been known what was 
 needed, but it was left for Messrs. Dellwik and Fleischer to 
 devise a practicable method of carrying it out. 
 
 In the old water gas process the producer gas 
 formed during the blows is amply sufficient for generat- 
 ing the steam needed for the process. When a com- 
 bustion to carbon dioxide is effected in the generator 
 this advantage is, of course, lost, the waste heat 
 being only sufficient for preheating the feed water for the 
 boiler. It is, therefore, necessary to add for boiler fuel 
 12 to 15 per cent, of the fuel used in the generator. This 
 reduces the theoretical quantity of gas obtainable from 
 121bs. of carbon to 656 cub. ft., and the possible utilisation 
 of the heating value of the fuel to about 80 per cent. 
 
 * Mr. Dellwik has taken slightly different values for the calorific power 
 of hydrogen and carhon from those used in this book. 
 
WATER GAS. 105 
 
 In these figures it will be noted that Mr. Dellwik 
 assumes that in the heating-up all the carbon is burnt to 
 carbon dioxide, and in the gas making to carbon monoxide 
 only. Neither of these conditions are likely to hold 
 good in actual practice. 
 
 According to the report of Prof. V. B. Lewes, the 
 blow-up gas contained 
 
 Carbon dioxide 17'9 18'8 
 
 Carbon monoxide .. ... 1'8 I'O 
 
 Nitrogen 78*6 79'5 
 
 Oxygen T7 0'7 
 
 whilst in other blows the carbon dioxide fell to 15'1 per 
 cent., and there is no doubt that in many cases it is much 
 lower. 
 
 The gas produced, as will be seen from the analysis on 
 page 109, is not quite free from carbon dioxide, so that the 
 actual efficiency is likely to be less than that here given 
 by an amount which will vary with the care with which 
 the process is conducted. 
 
 The Plant. Externally the producer does not differ much 
 from those of other types. The first form used was circular 
 and cased with iron, and had two projecting channels on each 
 side for the supply of fuel, at the top of each of which was 
 a charging hopper, instead of the usual single hopper in 
 the centre. At the top was a vertical chimney pipe 
 to carry off the products of combustion during the 
 heating-up stage, provided, of course, with a suitable 
 valve. 
 
 The newer forms of producer are circular, and have no 
 side chambers, but are fed at the top. They are up to 12ft. 
 diam. The producer is of the bar-bottom type, air being 
 supplied beneath the bars. The ashpit is provided with 
 a door for the removal of ashes, and above the ashpit is 
 another door for the removal of clinker from above the 
 bars. The combustion space is small, and the layer 
 of fuel comparatively thin. There are gas outlet 
 pipes and steam outlets at the bottom and top of the 
 producer, so that it can be worked alternately up and 
 down. The bars are in two sections, resting on a 
 hollow bar which crosses the centre of the producer, and 
 by which air can be blown in in addition to that which 
 passes through the bars. The producer is about 14ft. 
 high outside. The top is narrowed very much, so as to 
 
106 WATER GAS. 
 
 form a circular opening about 2ft. 6in. diam., which is 
 closed during the gas-making stage by a well-fitting lid. 
 Gearing is so arranged that the steam is shut off, and this 
 lid opened by the one motion of lever, and until this is 
 done the air cannot be put on. The air is supplied by 
 Root's blowers. , 
 
 Method of Working. The method of working is as 
 follows : A fire having been lighted on the grate, and the 
 generator filled to the proper level with coke, the blast valve 
 is opened, and the fire raised to a high state of incandescence 
 in a few minutes. One of the gas openings the upper 
 one, for instance is opened, the blast and stack valves 
 being simultaneously closed by means of the gearing on 
 the working stage. Steam is admitted at the bottom of 
 the generator, and is decomposed on its passage through 
 the bed of incandescent coke, resulting in the formation 
 of water gas. 
 
 A set of water gauges and a test flame indicate the condi- 
 tion of the apparatus and the quality of the gas coming off. 
 When the temperature of the fuel has sunk below the 
 point at which carbon dioxide begins to form in large 
 proportion, the steam is shut off and the stack valve 
 opened, the gas valve being simultaneously closed. The 
 blast valve is then opened for another blow. For the 
 next period of gas making the lower gas outlet is opened, 
 and the steam is admitted above the fuel. By thus 
 reversing the direction of the gas making the temperature 
 of the fuel is equalised, and the wear on the brick lining 
 at any one point is diminished. The greater part of the 
 coke being consumed by the action of the steam, the 
 incombustible part is disintegrated to a considerable 
 extent, and falls through the grate as ash, the clinkers 
 that remain on the grate are brittle, and are easily 
 removed. 
 
 The layer of fuel on the bars is in the large producers 
 about 4ft. thick. 
 
 When the gas-making stage is over, the cover 
 opened, and air put on, a large pale flame escapes from 
 the top of the producer. As soon as the charge is hot 
 enough the air is shut off, the top closed, and steam put 
 on, the opening and closing of the valves only occupying 
 a few seconds. In one plant gas was made for Smins., 
 
WATER GAS. 
 
 107 
 
108 WATER GAS. 
 
 and the heating up occupied 2mins. The flame during 
 the heating-up stage is allowed to burn at the top of the 
 producer on its way to the chimney, but the gas 
 produced during the gas-making stage is passed through 
 a superheater to heat the steam being supplied. 
 
 Doors are provided for cleaning the bars. This is 
 done about once every 24 hours, and as the layer of 
 fuel is very thin it may be burnt quite down before 
 cleaning, a fresh fire being afterwards lighted at starting. 
 
 After every second blow about 4 cwt. of fuel is added 
 by running a suitable hopper truck over the top opening 
 and letting the charge into the producer. 
 
 Results. The principal differences between this and the 
 earlier methods of making water-gas are in the relative time 
 of heating up and gas making and in the non-production 
 of producer gas. The heating up takes l'5min. to 2min. 
 and the gas making 8min. to 12min. The amount of gas 
 yielded is therefore large. 
 
 A series of tests of the Dellwik-Fleischer process were 
 made by Prof. Vivian B. Lewes, of London, who thus 
 sums up the result of his experiments. f 
 
 " One thousand cubic feet of water-gas, containing 
 151bs. of carbon, are obtained by a total expenditure of 
 291bs. of carbon, so that ove*r 51 per cent, of the carbon is 
 obtained in the gaseous form, while the expenditure of 
 49 per cent, results in the hydrogen of the water-gas. 
 
 " The coke used in the experiments made contained 
 87 '56 per cent, of carbon, or l,961'31bs. per ton, equal to 
 15,876,307 thermal units (C.), and this amount yielded 
 77,241 cub. ft. of water gas. The specific gravity, as 
 taken by the Lux balance, was *5365, and its gross calorific 
 value, as determined in Junker's calorimeter, was 4,089 
 thermal units. Hence the calorific value of the water gas 
 from a ton of coke was 13, 033, 059 '8 thermal units, or 
 over 82 per cent, of the heating value of the total coke 
 used in both generator and boiler. 
 
 "From this calculation 20 per cent, of the coke has 
 been taken as used for raising steam, but in a large 
 installation this figure could be reduced, and the percentage 
 of the total heating value of the coke obtained in the gas 
 slightly raised. The labour needed will be less than with 
 the ordinary process, as less fuel has to be handled." 
 
 t Dellwik, Journal of the Iron and Steel Institute, 1900, vol. i. 
 
WATER GAS. 
 
 109 
 
 Other tests made by Prof. Bunte of Karlsruhe, Prof. 
 Lunge of Zurich, Dr. Leybold of Hamburg, and others 
 have given similar results. The most trustworthy figures 
 for continued work have been obtained from an installa- 
 tion at the Corporation Gasworks at Konigsberg, in 
 Prussia, where an average yield of 38-44 to 39'72 cub. ft 
 of water gas are obtained per pound of carbon contained 
 in the coke which is charged into the generator. This 
 corresponds to a utilisation of 75 -2 to 7 7 '7 per cent, 
 of the calorific value of the fuel. At another gas-plant 
 the tests showed a yield of 41 -6 cub. ft. per pound of 
 carbon, or an efficiency of 81 '3 per cent." 
 
 It will be seen that the essential of the process is not 
 so much in the form of plant as in the fact that a very 
 thin layer of fuel is used and a very large excess of air is 
 blown in. 
 
 Water Gas. As already pointed out water gas consists 
 essentially of hydrogen and carbon-monoxide. The 
 following analyses will indicate its usual composition : 
 
 
 i 
 
 2 
 
 3 
 
 4 
 
 5 
 
 Hydrogen 
 
 52-43 
 
 50-09 
 
 52-76 
 
 49-17 
 
 51-0 
 
 Carbon-monoxide .. 
 Carbon-dioxide . . . 
 Methane 
 
 38-30 
 4-73 
 
 39-95 
 5-38 
 
 33-50 
 4-08 
 
 43-75 
 2-71 
 31 
 
 42-0 
 4.0 
 5 
 
 Oxygen . . 
 
 74 
 
 1-22 
 
 46 
 
 
 
 Nitrogen 
 
 3-80 
 
 3-36 
 
 5-20 
 
 4-00 
 
 2-5 
 
 
 
 
 
 
 
 Nos. 1, 2, 3 Dellwik-Fleischer analysis by Prof. Lewes. 
 No. 5 Dellwik-Fleischer average given by Mr. Dellwik. 
 As will be seen, the gas is nearly all combustible. 
 Taking No. 5 
 
 
 By Vol. 
 
 ByWeight. 
 
 C.P. 
 
 B.T.U. 
 
 Hvdrosren 
 
 51 
 
 6-7 
 
 1963 C.U. 
 
 - 3533 
 
 Carbon-monoxide .. 
 Carbon-dioxide . . . 
 Methane 
 
 42 
 4-0 
 5 
 
 76-7 
 11-5 
 5 
 
 1841 
 60 
 
 3314 
 108 
 
 Nitrogen 
 
 2-5 
 
 4-6 
 
 
 
 
 
 
 
 
 
 
 
 3864 
 
 6955 
 
110 WATER GAS. 
 
 Volume for volume the heating power is about twice 
 that of the best producer gas. 1,000 cubic feet weigh 
 about 431bs. and will therefore give about 166,152 C.U. or 
 299,065 B.T.U. 
 
 The gas is of course colourless and odourless, and 
 burns with a pale blue slightly luminous flame, hence it 
 is sometimes called blue producer gas, to distinguish it 
 from the gas enriched with various hydrocarbons which 
 burns with a luminous flame. 
 
 Carbon-monoxide is very poisonous, and so therefore 
 is water gas, and as it has no odour by which an escape can 
 be detected, many poisoning accidents have occurred with 
 it. To avoid this danger attempts have been made to 
 give the gas an odour by saturating it with some highly 
 odoriferous body such as carbon-disulphide. Water gas 
 may be used for lighting purposes by making it heat a 
 mantle or comb of some material which becomes highly 
 incandescent, or by charging it with some hydrocarbon 
 which will give the flame luminosity. 
 
CHAPTER IX. 
 
 CONDITIONS WHICH MUST BE FULFILLED BY A GOOD GAS 
 PRODUCER. THE AIR SUPPLY. SPEED OF GASIFI- 
 CATION. SHAPE OF PRODUCERS. SOURCES OF Loss 
 OF HEAT IN GAS PRODUCERS. QUALITY OF THE 
 GAS. CHARGING PRODUCERS. ASH REMOVAL. TAR 
 REMOVAL. AMMONIA RECOVERY. 
 
 WHILST among the producers described there are 
 differences in almost every point of detail, the principles 
 are the same in all cases. In any application of a process 
 or apparatus to a particular purpose real usefulness, and 
 therefore success, depends very largely on the careful 
 adjustment of details, and many processes perfectly 
 correct in principle have failed from lack of this. Hence 
 also very frequently a new idea takes some time to become 
 practically useful because the working out of the details 
 never comes by a flash of inspiration but by steadily 
 testing and correcting defects as they arise. 
 
 The conditions which a good producer must fulfil are 
 many. 
 
 (1) The gasification of the fuel must be complete. 
 This will depend on the design of the producer and the 
 method of air supply. 
 
 (2) It should allow the use of fuel of quality varying 
 within wide limits. 
 
 (3) The gasification must be rapid. Obviously the 
 more rapid the gasification the less plant will be required 
 for a given output of gas. 
 
 (4) The working must be continuous, or if stoppages 
 are essential they must be at long intervals and of as 
 short duration as possible. 
 
 (5) The quality of the gas must be good, that is, it 
 must be as rich as possible in combustible constituents. 
 
 (6) The loss of heat in the producer must be as small 
 as possible. 
 
 (7) The cost of labour and upkeep must be small. 
 
112 GAS PRODUCER CONDITIONS. 
 
 (8) The first cost should be small. This is, however, 
 of much less importance than the other considerations. 
 
 It is impossible to obtain a producer which will be 
 best in every particular, so that in all actual cases the 
 selection is more or less of a compromise. 
 
 Several points in connection with producers will be 
 briefly considered that will illustrate the conditions 
 mentioned above. 
 
 Air Supply. The conditions of gasification both as to 
 completeness of combustion and rate and uniformity of 
 gasification will depend largely on the air supply. In 
 general the air may be supplied in three ways 
 
 (1) From below, as in bar-bottom producers. 
 
 (2) From the centre, as in ordinary centre-blown 
 producers. 
 
 (3) From the circumference. 
 
 When the air is supplied from the bottom it is equally 
 distributed over the whole, or at any rate a large portion, 
 of the bottom of the producer. The area of air supply 
 is very large, and the air passes at once into the mass of 
 fuel. However large, therefore, the producer be, the air 
 supply will be fairly uniform. There is, however, an 
 objection to the air being supplied too near the circum- 
 ference, as it tends to creep up the wall, where resistance 
 is least, and some may even get through unburnt. In 
 the ordinary bar-bottom producers there is the disadvan- 
 tage of possible loss of fuel through the bars and the 
 trouble of clinkering, which may outweigh the advantage 
 of uniform distribution, though with suitable fuel this 
 may be to a large extent overcome by burning the fuel on 
 a bed of clinker. The necessity for clinkering limits the 
 size of producer which can be advantageously used. 
 
 In the Duff producer advantage is taken of the even 
 air distribution of the bar-bottom, whilst the objections 
 are to a large extent overcome. As, however, the bars do 
 not quite reach the outer wall there is a part of the fuel 
 into which the air is not supplied vertically. With the 
 long narrow grate it is found best to make the inside of 
 the producer rectangular in form, by building up inside 
 the circular casing, thus reducing the effective fuel area of 
 the producer. With any bar-bottom producer there is 
 always a danger of the production of clinker, which may 
 be difficult to remove. This is sometimes due to the 
 
GAS PRODUCER CONDITIONS. 113 
 
 use of a fuel which cokes, and which, therefore, hinders 
 the uniorm distribution of air, and allows the air only to 
 pass through the narrow cracks or crevices in the " caked" 
 mass, thus producing a very high local temperature and 
 consequent fusion of the ash, or it may be due to the fuel 
 containing a large amount of fusible ash. 
 
 With the central air supply the size of the producer 
 is limited by the power of the air to reach the circumfer- 
 ence, and this will depend somewhat on the blast pres- 
 sure. In the centre of the producer, where the steam and 
 air enter, there will be a zone of very vigorous 
 combustion just round the top of the entry pipe, and 
 as the air recedes from this combustion must become 
 much less vigorous, as not only is there the increased 
 resistance, but the stream of air and steam is constantly 
 spreading over a much larger area, and the free 
 oxygen is being rapidly removed. The temperature 
 must, therefore, fall off very rapidly, and there may 
 be a tendency for unburnt fuel to sink down round 
 the circumference. The air and steam are usually 
 delivered horizontally and rise upwards and outwards, 
 and thus, if combustion is complete, at the circumference 
 it will be at a much higher point than the centre. 
 
 The larger the diameter of the pipe by which the steam 
 and air enter the better, and in many producers this is made 
 far too small. The stream of air and steam should also 
 be delivered horizontally, so as to give as great an impetus 
 as possible towards the circumference. It is quite easy 
 to arrange the delivery in such a position that the 
 openings cannot be choked, even partially, by the descend- 
 ing ashes. As the air is delivered into the centre of the 
 fuel, equidistant at all points from the wall, there is 
 no possibility of unconsumed air creeping up the 
 walls. The zone of most intense combustion is as 
 far as possible from the walls, so that there is less 
 loss by radiation, and the walls are not likely to be 
 damaged by the intense heat. Provided (1) the diameter 
 of the producer be not too great, say, not more than 8ft. 
 or 10ft. ; (2) the air and steam pressure be sufficient to 
 reach the circumference of the producer; and (3) the 
 layer of fuel be sufficiently deep, centre blowing seems to 
 be the most suitable for gas producers, and has been most 
 
114 GAS PRODUCER CONDITIONS. 
 
 largely used. Centre-blown producers of very large size, 
 as a rule, do not work very satisfactorily. 
 
 The arrangement in the Wilson producer, where the 
 gas is delivered right and left from a central riclge or 
 main, appears to give a uniform combustion. 
 
 In producers blown from the circumference the air 
 and steam penetrate inwards, and therefore they have 
 less and less area to cover, but as the area at the outside 
 is very large the rate at which the gas enters is apt to be 
 small, unless tuyeres be used, placed some distance apart, 
 in which case fuel may escape combustion between 
 them, and there is the possibility of a central core of 
 unconsumed matter being left, and there is also the 
 possibility of air creeping up the walls. This method of 
 working gas producers is rarely used, though it is the 
 universal method of air supply in the blast furnace. 
 
 The conditions of uniform air supply limit the size 
 of producers of various types. A circular centre-blown 
 producer should not be above 8ft. or 10ft. diam., and 
 circumference-blown producers are usually narrowed to 
 much less than this at the zone where the air enters. 
 The size of bar-bottom producers is generally limited by 
 other conditions. 
 
 If the producer can be worked with a layer of clinker 
 above the air supply, so that the air blows into this and 
 not directly into the fuel, the air and steam will become 
 heated and the distribution may also be much more 
 uniform. This is, however, only possible where the fuel 
 leaves a good open clinker. 
 
 Speed of Gasification. The amount of fuel gasified will 
 depend on the amount of air and steam sent in, and this 
 will depend on the pressure and the area of the supply 
 pipes. Some figures have already been given, but the 
 following, which represent a case of actual work, may be 
 useful. 
 
 A Wilson or circular producer 8ft. diam. will gasify 
 about 4 cwt. of coal per hour, the area of the supply 
 being about 160 sq. in. A Duff producer 8 x 10 
 will gasify about 10 cwt. coal per hour, giving a gasifica- 
 tion of about 141bs. per square foot of bottom area, and, 
 of course, a larger amount per square foot of grate area. 
 The area of the air supply will be about 1,720 sq. in. 
 
LOSS OF HEAT IN PRODUCERS. 115 
 
 The conditions which decide the best speed of gasifica- 
 tion are many. If the air supply be too great, or if the 
 gasification be too quick, the temperature inside the 
 producer will become too high, and the gases will leave 
 at too high a temperature. The gas also may be swept 
 through so quickly that too large a quantity of carbon 
 dioxide may be left undecomposed. The more concentrated 
 the air supply in general, the slower will be the best rate 
 of combustion. 
 
 Attempts have been made to increase the efficiency 
 of the producer by super-heating the air and steam 
 supplied, and if by this means heat which would 
 otherwise be lost is carried back into the producer it 
 must lead to some economy. The methods used have 
 consisted either in circulating the air and steam through 
 passages in the masonry of the producer or in building 
 the producer with a double shell, so as to form an 
 annular space in which the air and steam can circulate. 
 
 An example of this arrangement has been described 
 in connection with the Mond producer, and another is 
 the Boyd producer (Fig. 28A). In this the lower part of 
 the producer has no firebrick lining, but consists only of 
 iron plates. Outside this is another casing, and into the 
 space D between the two the air and steam is supplied, 
 and enters the producer by the grate F. 
 
 Shape of Producers. The external form of the producer 
 is not of much moment. For producers standing alone 
 the cylindrical form is generally used, but when they can 
 be built in blocks, as is usually the case where a large 
 production is required, the rectangular form is most 
 convenient, as there is less surface exposed, and there- 
 fore less loss of heat by radiation, and the block is more 
 compact. 
 
 Sources of Loss of Heat to the Producer. The efficiency of a 
 producer depends on the amount of heat which is lost 
 i.e , which, being evolved in the producer, is carried 
 away before it can be used in the furnace. 
 
 The sources of loss of heat are : 
 
 (1) Heat carried away by the gases. 
 
 (2) Heat lost by radiation. 
 
 (3) Heat carried out by the ashes. 
 
 (4) Carbon-dioxide in the gas. 
 
 (5) Water in the gas. 
 
 \ / o 
 
 Heat Carried Out by the Gas. The higher the temperature 
 at which the gas leaves the producer, and the larger the 
 
116 
 
 LOSS OF HEAT IN PRODUCERS. 
 
 amount of gas per pound of fuel, the greater will be the loss 
 of heat in the gas. It may amount to as much as one-sixth 
 
 FIG. 3. 
 
 _D 
 
 FIG. 28A. BOYD'S GAS PRODUCER. 
 
 of the total heat evolved in the producer. How far this 
 heat is actually lost will depend on circumstances. If the 
 gas be carried hot to the furnace only, that heat which is 
 
LOSS OF HEAT IN PRODUCERS. 117 
 
 lost by radiation on the way can be really considered 
 as lost. Opinions differ as to whether the gas should 
 be used hot or cold. If the loss of heat can be prevented, 
 by using the sensible heat in any way, a cool gas is 
 probably best, but otherwise a hot gas is more economical. 
 A very hot gas often leads to trouble with the valves, 
 but much depends* on the conditions of working, and 
 whether it is desired to remove the tar or not. 
 
 Obviously, methods for reducing this source of loss 
 will be to use the gas hot, to utilise the sensible heat of 
 the gas in some way outside the producer, or to use such 
 a high column of fuel that the excess of heat will be 
 absorbed by it and thus saved in the producer. 
 
 Loss by Radiation. No estimate can be formed of this 
 loss; it will always be comparatively small, and will be 
 less in the case of producers built in blocks than in those 
 built separately. 
 
 Heat Lost in Ashes. This is always small in solid and 
 bar-bottom producers, and is practically nil in the case of 
 water-bottom producers. 
 
 Carbon-Dioxide in the Gas. The effect of carbon-dioxide 
 in the gas has been already pointed out, and it cannot 
 be too strongly insisted upon that for ordinary producer 
 gas the amount of carbon-dioxide is a measure of the 
 inefficiency with which the producer is working. The 
 usual cause of excess of carbon-dioxide is either a 
 producer badly designed, so that the carbon-dioxide formed 
 escapes without coming in contact with incandescent fuel, 
 or, more frequently, undue cooling by the use of too 
 much steam. 
 
 It is in the direction of reducing the amount of 
 carbon-dioxide that the producers need improvement, and 
 users should keep a constant check on the working in 
 this respect. 
 
 Steam in the Gas. The gas will always carry over the 
 water contained as moisture in the fuel charged, but 
 should contain no more; any larger quantity can only be 
 due to excessive steam supply. Steam has a very high 
 latent heat, and therefore will carry away a large amount 
 of heat, which cannot be recovered unless the steam be 
 condensed, a condition not likely to be met with in 
 practice. The specific heat of steam is also very high, so 
 that the loss of heat from excess of steam may be very 
 
118 
 
 QUALITY OF GAS. 
 
 considerable. When a large excess of steam is used 
 intentionally, as in the Mond process, elaborate condensing 
 appliances are necessary. 
 
 Sometimes when gases rich in tarry matters are used in 
 regenerative furnaces an excess of steam may be advan- 
 tageous, as it may be decomposed by the tarry matters in 
 the regenerators yielding carbon monaxide and hydrogen. 
 As a rule, however, too little steam is better than too 
 much. 
 
 Quality of the Gas. The quality of the gas depends on 
 the fuel and the amount of steam used. No producer can 
 
 FIG. 29. DUFF PRODUCER, WITH CHARGING HOPPERS. 
 
 be said in general to give a better gas than another, as 
 every producer in use is capable of giving the best quality 
 gas that is possible from a given fuel. On the other 
 hand, some producers are much more easily worked so 
 as to give the best gas which the fuel is capable of 
 yielding, continuously and regularly. The principal con- 
 ditions on which this depends are uniformity of distribution 
 of air and steam, ease of regulating air and steam supply, 
 sufficient thickness of hot fuel to decompose any carbon- 
 dioxide formed, and uniform distribution of the fuel. 
 
CHARGING PRODUCERS. 119 
 
 Analyses of gases published by manufacturers of different 
 types of producers to show the quality of gas produced 
 are quite useless unless the nature of the fuel used and 
 the exact conditions of working be fully known. 
 
 Charging Producers. Producers are always charged by 
 means of a hopper fitted with sliding or lowering doors, 
 so that the fuel can be put in without admitting air. The 
 exact arrangement of these hoppers varies much. In 
 circular producers there is usually a single hopper in the 
 centre, and this answers well for producers of small size, 
 but it must always be remembered that the fuel from the 
 hopper will form a natural slope, so that the depth of the 
 charge will be greatest under the hopper and least farther 
 away. For large producers two hoppers are sometimes 
 used. For a centre-blown producer the fuel should be 
 supplied in the middle. The finer material will thus form 
 the middle of the mass, whilst the larger lumps will roll 
 off towards the circumference, thus offering an easier 
 passage to the gas near the circumference, and insuring a 
 good distribution of air and steam. 
 
 Automatic charging is now largely used. Of the many 
 devices the simplest consists of a rotating cylinder placed 
 below the hopper and provided with a longitudinal open- 
 ing, so that when this comes under the hopper the 
 cylinder fills with fuel, and as it is then rotated the 
 charge is emptied as the opening comes round over the 
 mouth of the producer. By regulating the speed of rota- 
 tion of the cylinder, the amount of fuel supplied can be 
 adjusted. 
 
 In the top of the producer test holes should be 
 provided by which rods can be put in to ascertain that 
 the fuel is descending uniformly. 
 
 The tops of the producers are usually united to form 
 a charging platform, and rails should be laid so that the 
 coal can be brought up in bogies and charged at once 
 into the feeding hoppers. In some cases a large supply 
 bin is fixed above the producers with shoots leading to 
 the various hoppers, so that the fuel can be let down 
 at once for charging. 
 
 Ash Removal. The removal of ash is of the utmost 
 importance. In the intermittent producers there must be 
 an accumulation of ash between the times of cleaning, so 
 
120 TAR REMOVAL. 
 
 that the height of the zone of combustion must be con- 
 tinuously increasing. In water-bottom producers the ash 
 should be removed regularly at short intervals, and care 
 should be taken to draw the ash not only from the outer 
 edge, but from over the whole area of the producer, 
 for thus alone can the uniform fall of the charge and 
 uniform combustion be secured. The ash removal is 
 most uniformly carried out in the automatic producers. 
 If the fuel yields a firm clinker, it may be desirable 
 to provide some mechanical means by which it can be 
 broken up. The details of any such appliance will 
 depend on the form of producer to which it is applied. 
 
 Coking Coals in Gas Producers. Coking coals are, as a 
 rule, unfit for use in gas producers, since on heating 
 they become pasty, and as the volatile matter is 
 expelled yield a solid mass, which prevents the passage 
 of the gas. If such coals have to be used the coke 
 must be broken up by some mechanical device. A 
 coal which yields a very fusible clinker may also lead 
 to trouble, unless the clinker be broken up mechani- 
 cally. 
 
 In the Fraser-Talbot producer, made by the Wellman- 
 Seaver Engineering Company, a vertical rod passes down 
 the centre of the producer which is of the water-bottom 
 type and carries two radial arms which are placed at 
 different angles. The shaft can be rotated by means of 
 gearing, and can also be raised or lowered by means of 
 a hydraulic cylinder placed above, and is provided with 
 springs which will yield if there is undue resistance to 
 the motion of the shaft, and thus lessen the chance of 
 fracture. The shaft is rotated very slowly about once 
 in 10 minutes and the vertical motion occupies about 
 the same time, and thus coke and clinker is very effectually 
 broken up. To keep the shaft arid arms cool they are made 
 hollow, and a stream of water is kept constantly circu- 
 lating through them. 
 
 Tar Removal. When producer gas is made from 
 bituminous coal it is always charged with tarry matter, 
 the amount of which will vary with the character of the 
 fuel. The crude tar may reach as much as 15 per cent, 
 of the weight of the coal consumed. There will also be a 
 certain quantity of ammonia, the amount depending on 
 
TAR-FREE GAS. 121 
 
 the nature of the fuel and on the amount of steam used. 
 The nature and composition of the tarry matters depends 
 largely on the temperature and rate of distillation. 
 
 The tar is combustible, and therefore adds to the 
 heating power of the gas. The tarry matter is not given 
 in an ordinary analysis of a producer gas, the analysis of 
 the crude and washed gases being identical, because in 
 the preparation of the sample for analysis the tar is com- 
 pletely removed. 
 
 The removal of the tar from a gas necessarily lowers 
 its heating power, but it is impossible to say to what 
 extent possibly 10 per cent. ; indeed, one manager who 
 has had considerable experience gave it as being as much 
 as 20 per cent. The removal of the tar also reduces or 
 destroys the luminosity of the flame. 
 
 If the furnace be far from the producer, and the gases 
 are cooled, there will always be some deposition of tar, 
 though in any case, unless the gas be thoroughly washed, 
 the removal will be far from complete. There will always 
 be a deposit of soot and very thick tar in the mains 
 which must be burnt up periodically. 
 
 Whether the tar should be removed or destroyed will 
 depend on circumstances. In boiler firing and in other 
 cases where heating by radiation is required the tar is 
 best left in the gas, but for use in the regenerative furnace 
 a tar-free gas is preferable, whilst for use in gas engines 
 the gas must not only be tar free but also dust free. A 
 tar-free gas may be obtained in three ways: 
 
 (1) By using a material which yields no tar. This is 
 not always easy, as even coke-fed producers may pro- 
 duce a small quantity of tar, so that when the gas is to be 
 used for gas engines it must be washed to remove this 
 and the dust. 
 
 (2) By destroying the tar. The method of doing 
 this by passing the gas through the hot fuel has already 
 been explained, but the tar removal by this method is- 
 generally by no means perfect. 
 
 (3) By washing. In this case the gas is usually cooled 
 and scrubbed by passing up towers down which a stream 
 of water is kept falling, or is washed by being bubbled 
 through or agitated with water. In either case the 
 removal of the tar is complete. Gas for use in gas 
 
122 
 
 TAR DESTRUCTION. 
 
 engines is always washed or scrubbed. When the gas is 
 so treated it must necessarily enter the furnace cold. 
 
 Up to the present no attempt has been made to 
 recover the tar from gas producers. 
 
 Tar Destruction. The method of destroying the tar 
 in the Wilson producer has already been described, and a 
 similar method might be used in conjunction with any 
 other producer. 
 
 Mr. Matthewman stated in a paper read before the 
 West of Scotland Iron and Steel Institute that the method 
 
 FIG. 30. THWAITE TWIN PRODUCES. 
 
 of drawing off the gas from below the surface of the fuel 
 merely limited the zone of combustion, that the gas found 
 its exit by the nearest possible route, and the fresh fuel 
 did not become decomposed to any appreciable extent 
 until it had fallen into the route of the gaseous current. 
 The tarry matters were therefore not decomposed, but 
 accumulated in the closed upper part of the producer 
 and the gas was practically the same as if made from 
 coke. 
 
TAR DESTRUCTION. 
 
 123 
 
 This statement undoubtedly contains some truth, but 
 seems to be exaggerated ; the tar destruction is not by any 
 means complete, but some of the tar seems to be 
 destroyed. 
 
 The process has been a little modified by Mr. Thwaite 
 in his twin producer. This is a bar-bottom producer, 
 and the upper portion is divided into three parts by two 
 hanging walls carried on arches thrown across the 
 producer. The fuel is charged into the two outer spaces, 
 and the gas is drawn off from the middle space. 
 Although the gas is drawn off very low down, it does 
 
 u 
 
 n 
 
 FIG. 31. THWAITE DUPLEX PBODUCEB. 
 
 if the tar destruction would be any more 
 in the Wilson form, while the gas, being 
 
 not seem as 
 
 perfect than 
 
 drawn off near the bars, would leave the producer at a 
 
 high temperature, and might carry a considerable quantity 
 
 of carbon dioxide. 
 
 In the Thwaite duplex producer two producers are 
 used side by side. They are united at the bottom and 
 at the top by cross tubes. The bottom cross tube can be 
 put into connection with the air and steam supply and the 
 gas main, and is provided with valves so that the direction 
 of the current can be changed, and thus air and steam can 
 
124 
 
 TAR DESTRUCTION. 
 
 be supplied to and gas can be drawn off from either 
 producer. Fuel is supplied at the top alternately 
 to the two producers, and a steam jet is arranged so 
 that steam can be supplied at the top of the producers. 
 The mixture of air and steam is blown as usual into the 
 bottom of one producer, say the left-hand one. The gas 
 passes upwards, mixes at the top with the products of 
 distillation, and then, together with any steam blown in 
 at the top, passes downwards through the other producer, 
 the steam and tarry matters being completely broken up 
 on their way to the gas main. The current is reversed 
 every 10 minutes or so, and the gas is said to be quite 
 free from tar, steam, and carbon dioxide. 
 
 FIG. 32. THWAITE NON-REVERSAL, PRODUCER. 
 
 The Thwaite non-reversal producer is very similar, 
 two producers being worked side by side, but the current 
 of gas always passes in the same direction, a supply of 
 air and steam being blown in at the top of the first 
 producer so as to maintain the temperature in the second 
 producer sufficiently high. 
 
TAR DESTRUCTION. 125 
 
 The Duff-Whitficld Producer. This producer is the best 
 that has yet been designed for tar destruction, and 
 leaves little to be desired. The producer is of the 
 ordinary Duff type except that, as greater pressure is 
 required, the air is supplied by a fan or blower instead of 
 by a steam jet, the steam being blown in from a boiler 
 separately. The gas is drawn off to the mains by a 
 pipe some distance below the top of the charge. A pipe 
 passes from above the top of the fuel, and another from 
 a little lower level to vertical pipes reaching nearly 
 to the bottom of the producer, and into each of these 
 a steam jet blows and carries the gas forward into the 
 bottom of the producer. The suction of these steam jets 
 draws enough of the hot gas up through the fuel to 
 insure the distillation of the coal, and the products of 
 distillation are thus carried round and delivered into the 
 hottest zone of the producer, where they are completely 
 destroyed. The gas is thus quite tar free. 
 
 Washing Gas. A large number of different forms of 
 apparatus have been devised for the removal of dust and 
 tar from gas which is to be used for gas engines. The 
 methods consist in passing the gas up towers packed 
 with some suitable material, where it meets a descending 
 rain of water, and thus the dust and tar are washed out, 
 or in bubbling the gas through water, this being, as a 
 rule, much less efficient, or, as in many modern types of 
 plant, agitating the gas with water by means of dashers 
 or other mechanical appliances. This is perhaps the most 
 efficient, and at the same time the cheapest, method of 
 bringing about the desired cleansing. 
 
 Ammonia Recovery. The recovery of ammonia has 
 already been discussed in connection with the Mond 
 plant. No attempt has been made to recover the ammonia 
 from gas producers worked in the ordinary way, as the 
 quantity would be too small to be profitable. The method 
 of Dr. Mond, i.e., the use of a large excess of steam, 
 could no doubt be applied to producers of almost any 
 type, provided efficient condensing plant be provided. 
 It has been quite successfully carried out with Duff pro- 
 ducers. 
 
 Initial Cost. The initial cost of the simple types of 
 producer is small, as they are very easily built. The 
 actual cost will, of course, vary with circumstances. 
 
126 
 
 DUFF-WHITFIELD PRODUCER. 
 
 FIG. 33. SECTIONAL ELEVATION AND PLAN OF THE DUFF-WHITFIELD 
 GAS PRODUCES. 
 
COST OF PRODUCER GAS. 127 
 
 Cost of Labour. The cost of labour is small, as one man 
 can attend to two or more producers, and additional 
 labour will only be required for removal of the ashes. 
 
 Cost of Repairs. The cost of repairs is small in a well- 
 built producer, but may be considerable if the producer has 
 been badly built at the outset. A well-constructed 
 producer should run for two years or more without needing 
 repair. 
 
 Cost of Gas. The cost of the gas will be made up of 
 many items, each of which may vary considerably under 
 different circumstances and in different localities. 
 
 Mr. F. J. Rowan has given the following estimate of 
 the cost of gas-making in Duff producers, each producer 
 gasifying 10 cwt. of coal per hour, and working 60 hours 
 per week, coal at 10s. a ton yielding 150,000 cub. ft. of 
 gas per ton, and labour costing Is. per ton. 
 
 Coal -80d. 
 
 Labour *08d. 
 
 Interest and depreciation... -20d. 
 
 l-08d. per 1,000 cub. ft. of gas. 
 
CHAPTER X. 
 
 USES OF GASEOUS FUEL. FIRING STEAM BOILERS. 
 FURNACES. THE REGENERATIVE FURNACE. THE 
 WEARDALE FURNACE. GAS KILNS. GAS ENGINES. 
 CONTROL OF PRODUCTION. 
 
 Using Gaseous Fuel. Gaseous fuel is available for all 
 purposes for which solid fuel can be used, except for 
 firing furnaces of the blast-furnace type. Its advantages, 
 however, will not be equally marked in all cases, nor, 
 indeed, can it be asserted that it will always, and under 
 all conditions, have an advantage over solid fuel. 
 
 There are, in general, four purposes for which gaseous 
 fuel may be used, and as each involves a different set of 
 conditions and has very different requisites for success, 
 they are best considered separately. 
 
 They are (1) Firing boilers for steam-raising. 
 
 (2) Heating furnaces without regeneration. 
 
 (3) Heating regenerative furnaces. 
 
 (4) Working internal-combustion engines. 
 Firing Steam Boilers. It must be admitted at the outset 
 
 that for boiler firing gas has not proved such a success as 
 many anticipated, though many published results will 
 bear comparison with those obtained with boilers fed 
 with solid fuel. 
 
 The first attempts at boiler firing by means of 
 gas consisted in placing the fireplace outside the 
 boiler and so enlarging it as to make it a gas producer, 
 each boiler, therefore, having its own producer. Such an 
 arrangement offers no advantages whatever over the 
 ordinary methods of firing ; the powerful radiation of the 
 solid fuel is lost, and the great advantage of gas, i.e., that 
 of being able to make it at a central producing plant and 
 distribute it as required, is not obtained. Such methods 
 are therefore necessarily defective, and call for no further 
 comment. 
 
 The conditions which hold in boiler heating are very 
 different to those in the heating of an ordinary furnace. 
 The boiler will be full of water which can never attain 
 a high temperature, and therefore will have a very 
 
USES OF GASEOUS FUEL. 
 
 129 
 
 powerful cooling effect on the burning gases, and will 
 produce a thin layer of cold gas, a zone of no combustion, 
 all over the heating surface. The heating, therefore, will 
 not be by contact but by radiation, and hot gases are very 
 poor radiators. 
 
 Where gas is used, therefore, every effort must be 
 made to increase the radiative power, and also the 
 temperature of the flame and of the products of 
 combustion. For the former purpose the gas should not 
 be deprived of its tar, as a luminous flame has an 
 enormously greater radiative power than a one which is 
 non-luminous. The calorific power of a gas is, as 
 already remarked, considerably reduced by the removal of 
 
 FIG. 34. COMBUSTION CHAMBER FOR LANCASHIRE BOILER. 
 
 the tarry matter, but the heating power, as measured by 
 its steam-raising capacity, is reduced in much larger 
 proportion. Washed gas is therefore quite unsuited for 
 steam raising. 
 
 Producer gas has a low calorific power, and if it be 
 burnt in a cool space such as the furnace of a Lancashire or 
 Cornish boiler, the temperature attained will be very low, 
 and therefore the radiative power will be very small, and 
 the flame is very likely to be extinguished, or at least the 
 combustion rendered incomplete. This difficulty is over- 
 come by burning the gas in a separate brick-lined 
 chamber outside the boiler, or sometimes within it. 
 The brickwork then becomes heated to strong redness, 
 
130 
 
 USES OF GASEOUS FUEL. 
 
 and thus keeps up the temperature of the gas. An 
 arrangement of the brickwork in such a way that it can 
 
 FIG. 35. COMBUSTION CHAMBER FOR GAS-FIRED BOILER. 
 
 radiate the heat directly on to the water spaces of the 
 boiler is a very great advantage. 
 
USES OF GASEOUS FUEL. 
 
 131 
 
 Fig. 34 shows a very good arrangement for burning 
 gas in an ordinary Lancashire boiler, and Fig. 35 shows 
 another type which is provided with grate bars, so that a 
 fire can be lighted, and can be kept burning if required. 
 This is, however, quite unnecessary once the brickwork has 
 been heated up to a good red heat. In place of having a 
 separate combustion chamber the boiler flue itself may 
 be lined with brickwork for a length of 4ft. or 5ft. The 
 heat transmitted through the brickwork thus becomes 
 available for heating the water instead of being lost. 
 Fig. 36 shows an arrangement for heating a water- 
 tube boiler in this case a Babcock and Wilcox the 
 firebrick grating becoming very hot and thus assisting 
 
 FIG. 36. GAS-FIRED WATER-TUBE BOILER. 
 
 in the radiation. Whatever form of boiler be used, the 
 air must be supplied by a valve of some sort by which 
 the supply can be regulated. Some firemen seem to 
 think that a gas fire once started can be left to itself 
 without any care, but this is certainly not the case if 
 good results are to be obtained. One of the chief 
 essentials for the successful use of gas under boilers 
 is to burn it with the least possible excess of air, and the 
 richer the gas the smaller the excess of air which is 
 necessary. 
 
132 
 
 USES OF GASEOUS FUEL. 
 
 It is not possible to apply the regenerative system to- 
 boiler firing because the products of combustion leave the 
 boiler at far too low a temperature. The temperature of 
 the gases is never very high and most of the heat is 
 necessarily taken up by the boiler itself. The waste gas 
 may, however, be used for heating the feed water or for 
 heating the incoming air, but intermittent systems are 
 quite out of the question. A continuous system such as 
 
 FIG. 37. 
 
 that of Gorman might be used, and an arrangement said 
 to work satisfactorily with blast furnace gases has been 
 introduced by Mr. Tate, of Workington. In this system 
 the furnaces and flues are surrounded by firebrick re- 
 generative chambers Fig. 37, which become heated by 
 the products of combustion. The air enters the lower 
 regenerative chamber at the front of the boiler and is 
 made to take a tortuous course through it by means of 
 
USES OF GASEOUS FUEL. 133 
 
 firebrick partitions ; it then travels back by the side 
 chambers, and is delivered into the combustion chamber. 
 In one set of experiments the air had a temperature of 
 480 Fah., and in another set a temperature of 735 Fah. 
 These temperatures are very low compared with those 
 obtained in the Siemens furnace, but are high enough to 
 be of real advantage in working the boilers. It is 
 uncertain, however, whether greater practical effect 
 could not be obtained by using the waste heat to heat 
 the feed water. 
 
 The figures that have been published with reference 
 to the gas firing of boilers are of little value, as in many 
 instances the arrangements for the gas firing were very 
 crude. 
 
 The evaporation obtained has varied very much. 
 From a large number of published figures about 5'51bs. 
 per pound of coal used in the producer seems to be a fair 
 average, but the quality of the coal is of course of 
 
 S-eat importance. In some experiments made by 
 . K. Clark firing by solid fuel and by gaseous fuel 
 were compared, the same coal being used in both cases. 
 The evaporation obtained was 5'711bs. per pound of coal 
 with hand firing and 5'671bs. by gas firing. In another 
 set of experiments made by Mr. Rowan with a multi- 
 tubular boiler an evaporation of 9'491bs. per pound of 
 coal gasified was obtained. It should be noted that 
 comparisons with the same fuel gasified in producers or 
 used by hand firing are of little practical value, since in 
 almost all cases a cheaper fuel can be used for gas making 
 than is suitable for hand firing. 
 
 Gaseous fuel has not yet been very largely used for 
 boiler firing. The boiler the arrangement of which is 
 shown in Fig. 38 is being satisfactorily worked with gas 
 from a Duff producer, and blast furnace gas is largely 
 used in iron works for steam raising. As, however, the 
 .gas is passed directly from the blast furnaces it is 
 impossible to obtain any figures as to its efficiency, but 
 the method of combustion used is certainly very wasteful. 
 
 The newer gases, such as Mond gas and water gas, 
 have been little used for boiler firing. No doubt, however, 
 they would be as satisfactory as any other non-luminous 
 
 Where boilers have to be kept going singly, or all in 
 one block, it does not seem as if gas fuel has much 
 -advantage over solid fuel, especially if automatic stokers 
 
134 
 
 USES OF GASEOUS FUEL. 
 
 be used ; but where tbe boilers are scattered so that coal 
 would have to be delivered in many places, gas might 
 have decided advantages. 
 
 The advantages of gaseous fuel for boiler firing may 
 be summed up as follows : 
 
 (1) The fire can be kept at a uniform temperature, 
 there being no necessity for the constant opening of the 
 
REGENERATIVE FURNACES. 135 
 
 furnaces for the supply of fuel as in hand firing, nor 
 is the fire cooled by the addition of cold fuel. To obtain 
 the best results, however, the boilers must receive 
 constant attention. 
 
 (2) The gas can be generated in one place and 
 conveyed by pipes to the boilers, wherever they may be 
 situated. 
 
 (3) Less labour will be required at the boilers, and 
 the labour required at the producers will be much less 
 than that which would be required to stoke in the 
 ordinary way. These advantages are so considerable 
 that probably in the future gas will be much more largely 
 used for steam-raising than it has been in the past. 
 
 Furnaces Without Regeneration. For heating ordinary 
 reverberatory furnaces without regeneration, gas has 
 much the same advantages and disadvantages as for 
 steam-raising. As the furnace itself will probably be 
 red-hot, a separate combustion chamber is not necessary, 
 and the products of combustion being at a high tempera- 
 ture may be used for steam-raising or other purposes. 
 This method of using gas offers so few advantages that 
 it is rarely used ; indeed, in one sense the ordinary coal- 
 fed reverberatory furnace is a gas furnace. 
 
 Siemens Regenerative Furnace. The first and best known 
 of the regenerative furnaces is that invented by Sir Wm. 
 Siemens. In this, as is well known, four regenerative 
 chambers are placed beneath the furnace, and are filled 
 with a chequer work of fire brick. The air and gas are 
 passed up through two of these regenerators, and the 
 products of combustion are passed away through the 
 other two to the chimney, the direction being reversed 
 every hour or so. The air and gas are thus very strongly 
 heated before they come into the furnace, and a very high 
 temperature is produced by the combustion. 
 
 Furnaces of this character are now very largely used 
 for many purposes, especially for steel melting, and they 
 are now made of very large size. Indeed, at present no 
 limit has been found to the advantageous size. The air 
 and gas are admitted by ports. The two ends of the 
 furnace are exactly similar. The gas ports are rectangular 
 openings, two or three in number, and the air port is 
 usually a long narrow opening close to the roof, and 
 extending nearly the whole width of the furnace at any 
 rate, far enough to overlap the gas ports at both ends. 
 
136 
 
 REGENERATIVE FURNACES. 
 
 The gas ports are below and the air ports above, because 
 the light gas will tend to rise and the heavier air to fall, 
 so that perfect mixture is thus ensured, and the furnace 
 becomes filled with a long flame extending from end to 
 end. 
 
 In the earlier forms of furnace the roof was always 
 built so as to dip towards the middle and to deflect the 
 flame downwards. Mr. F. Siemens, however, contended 
 that this is a mistake, as contact with the hot brickwork 
 
 FIG. 39. DIAGRAM OF SIEMENS FURNACE. 
 
 tends to induce dissociation and thus to limit the 
 temperature which is attainable by combustion, and 
 he suggests that the roof should be made somewhat 
 higher in the centre so as to give enlarged space for 
 combustion. Most furnaces are now built with the roof 
 nearly horizontal over the main part of the furnace, but 
 rising sharply near the ends to the air ports. 
 
 The essential part of the apparatus is the regenerators. 
 These may be of any form and may be placed in various 
 positions, but should always be below the level of the 
 
REGENERATIVE FURNACES. 
 
 137 
 
 furnace floor so that the hot air and gas may tend to rise 
 freely into the furnace. In the Siemens furnace the 
 
 chambers are usually under the body of the furnace, but 
 in some recent forms they have been put under the working 
 platform instead, a position which has the disadvantage of 
 
REGENERATIVE FURNACES. 
 
 139 
 
 making this platform unduly hot. In the Batho furnace 
 they are placed in separate iron casings outside the furnace, 
 but not below it, and occasionally they are put above the 
 furnace, which is, however, the worst possible position. 
 
 The length of the regenerative chamber, i.e., from 
 back to front, is, in ordinary cases, determined by the 
 width of the furnace, the breadth is determined by 
 the available space under the furnace, so as to allow the 
 flues to rise nearly vertically, so that the only dimension 
 that can be modified is the depth. 
 
 The volume of air required for complete combustion 
 is rather larger than that of the gas burnt, and as both 
 should be delivered at approximately the same tempera- 
 ture the air regenerator is usually made somewhat larger 
 
 FIG. 41. VALVES FOE SIEMENS FURNACE 
 
 than that for the gas. The difference may be even 
 greater than the ratio of air to gas, because the 
 gas is usually delivered to the regenerators at a higher 
 temperature than the air, and therefore requires less 
 heating. The difference in size is usually obtained 
 by varying the width of the chamber, since the 
 other dimensions must necessarily be uniform. No 
 general rule is adopted. Some engineers make the 
 chambers the same size, others make the air chamber 
 half as large again as the gas chamber ; a ratio of 4 to 5 is 
 probably a very good one in most cases. 
 
 The deeper the chamber the more heat will be taken 
 up, and therefore, as a rule, the better will be the results. 
 
140 REGENERATIVE FURNACES. 
 
 The tendency of late has been to greatly increase the 
 depth till it has reached 16ffc. or 20ft., and even this is not 
 the limit. There is, of course, a practicable limit, due to 
 the need for maintaining a draught. The hot products of 
 combustion would tend to rise back into the furnace if 
 they were not drawn forward by the chimney draught. 
 The limit to the depth of the regenerator chamber, 
 therefore, would be reached when this back pressure 
 approached so near the pressure in the chimney as 
 to interfere with the draught. 
 
 The valves are another very important part of the 
 furnace, many forms having been designed. It is very 
 important that the valves should be perfectly tight, or there 
 will be great loss of gas. The usual form of valve is the 
 simple cast-iron butterfly valve working in an iron casing. 
 
 The maximum rate of combustion will, of course, be 
 determined by the chimney draught, which must be 
 sufficient to carry away the products of combustion as 
 quickly as they are formed when air and gas are being 
 supplied at the greatest speed. 
 
 The Siemens regenerative system is by no means 
 confined to steel making, but is applicable to any 
 purpose where a very high temperature is required, 
 and it is largely used in glass making and many other 
 industries. 
 
 Gas for Regenerative Furnaces. Any form of gas may be 
 used. Ordinary producer gas is that in general use, but 
 Ivlond gas, water gas, and washed blast-furnace gas have 
 been used successfully. It is obvious that, in order to 
 .get the best results, the furnace must be designed for 
 the gas to be burnt, for, among other things, the quantity 
 of air required for combustion will vary with the nature 
 of the gas the richer the gas the more air being required, 
 but at the same time the less the excess that need be 
 supplied, an excess of but 1 per cent, being sufficient in 
 the case of water gas. 
 
 The gas should be clean. Dust is very objectionable, 
 as it tends to clog the regenerators and also to flux away 
 the bricks. Tar is also objectionable. When tar is 
 carried over into the hot chambers, it is decomposed by 
 contact with the hot brickwork into gaseous products 
 which pass over with the gas and solid carbon which is 
 deposited. When the gas is reversed, the excess of air 
 in the products of combustion burns the carbon. This 
 produced a high local temperature which may help to 
 
REGENERATIVE FURNACES. 141 
 
 flux away the bricks, and at the same time it increases 
 the temperature of the products of combustion. 
 
 It does not seem to be much advantage to supply the 
 gas hot to the regenerators ; indeed, Siemens contended that 
 the only result of so doing was to increase the temperature 
 of the chimney gas. The hotter the gas is supplied, the 
 smaller should be the gas regenerator in proportion to 
 that for air. 
 
 The recovery and utilisation of the waste heat gives 
 the regenerative furnace a very high degree of efficiency, 
 far greater than can be attained in any other form of 
 furnace. 
 
 Other Forms of Regenerative Furnace. Various other forms 
 of regenerative furnaces have been designed. In the 
 furnace called the Siemens new type (Fig. 42), designed by 
 Mr. F. Siemens and described before the Iron and Steel 
 Institute in 1889 by Messrs. Head and Pouff,* only two 
 regenerators are used, those for the air, the gas being 
 sent into the furnace hot from the producer. Another 
 peculiarity of this furnace is that the gas and air enter, 
 and the products of combustion leave, the furnace at the 
 same end, or rather perhaps side, it being in this case 
 the longer dimension of the furnace. The arrangement 
 will be made quite clear by the illustration. 
 
 Gas from the producer B passes through the flue C' 
 to the gas port and thence into the combustion chamber 
 h'g' '. Air for combustion passes through the combustion 
 chamber A' by an air flue and the port H' into 
 the combustion chamber, where it meets the gas, 
 and combustion takes place. The flame sweeps round 
 the hearth E, and the products of combustion pass 
 away by h g and go partly through the regenerator A, 
 and partly through the gas producer B to be converted 
 into combustible gas. From time to time the air regene- 
 rators and the gas from the producers are reversed as 
 usual. 
 
 The products of combustion are at a very high 
 temperature, and contain carbon dioxide and water 
 vapour. These are decomposed by the hot carbon, 
 carbon monoxide and hydrogen being formed, and there- 
 fore it is often said that the products of combustion are 
 regenerated as well as the heat. These furnaces have 
 at present been mainly used for heating plates, billets, 
 &c., and similar purposes. 
 
 * J. I. and S. L, 1889, Vol. II. 
 
142 NON-REVERSING REGENERATIVE FURNACES. 
 
 Non-reversing Furnaces. In the Siemens furnaces (Fig. 
 40) the direction of the air and gas have to be reversed 
 periodically by means of suitable valves, and many 
 
 Www^W*^w 
 
 attempts have been made to devise a furnace in which 
 good results shall be obtained without changing the 
 
THE WEAHDALE FURNACE. 
 
 143 
 
 direction of the flame. The best known of these is 
 probably the Gorman heat-restoring furnace. In this 
 the products of combustion are made to circulate round 
 fire-clay tubes, through which the air passes on its 
 way to the furnace. No data have been published 
 from which the efficiency of the furnace can be judged, 
 but it does not seem as if the regeneration would be 
 very great, the heating surfaces being small, and it 
 would be best suited for cases in which the products 
 of combustion were not at a very high temperature. 
 
 FIG. 43. THE GERMAN FURNACE. 
 
 The Weardale Furnace. This is the latest form of furnace 
 with continuous regeneration, and it is being largely and 
 very successfully used for heating bars, plates, and similar 
 purposes. This is shown in Fig. 44. 
 
 The furnace may be of any length ; that shown is 30ft. 
 long. The gas enters from the producer by the gas main 
 O and passes through the ports K into the space M between 
 the two roofs of the furnace. Here it meets the hot air, 
 which, entering by openings into the flues C, passes to 
 the heating chamber M. Combustion takes place as the 
 gas and air meet, and the flame passes through the opening 
 L into the furnace, where it spreads out and forms a sheet 
 of flame. 
 
144 
 
 THE WEARDALE FURNACE. 
 
 The products of combustion pass away by the openings 
 D, and may be used for steam raising or any other purpose. 
 The furnace is, of course, provided with suitable working 
 doors arranged according to the purpose for which it is to 
 be used. In this case a slag hole is provided at J, towards 
 which the hearth is made to slope. 
 
 / H 
 
 J , / m 
 
 FIG. 44. THE WEARDALE FURNACE. 
 
 The mode of lighting is as follows : After the whole 
 of the brickwork of the furnace has been thoroughly 
 dried by tires kept burning in the interior for a sufficient 
 
GAS KILNS. 145 
 
 length of time wood being the best fuel for this purpose 
 the gas is admitted by means of a valve, and is ignited 
 by the fire left burning for the purpose. The process of 
 putting gas in is a little different from that adopted in 
 starting a melting furnace. In the case of new furnaces 
 all the doors must be closed before the gas is admitted, in 
 order that a through draught from the air inlets to the 
 chimney may be established. This effectually prevents 
 any spreading of gas between the roof arches, where it 
 might cause an explosion. The gas invariably lights 
 quietly, and without the slightest puff. 
 
 In one case given by Mr. Hollis a furnace with a 
 heating chamber 34ft. 6in. by lift, heated 910 tons of 
 slabs in a week, with a consumption of 2'37cwt. of coal 
 per ton of slabs, and in another case a furnace with a 
 heating chamber 39ft. by 7ft. heated 600 tons of slabs 
 with a coal consumption of 2'4cwt. per ton. 
 
 The waste heat was carried to Lancashire boilers, and 
 gave an evaporation of 6'231bs. of water per pound of coal 
 consumed. 
 
 One or two other types of gas-heating furnaces may 
 be mentioned. 
 
 The Dunnachic Kiln. This illustrates the application of 
 gas firing to quite a different purpose, viz., the burning 
 of bricks or other similar articles. Regenerator chambers 
 are not required, as the bricks serve to heat the incoming 
 air. The kilns are built in sets of 10, in two rows of 
 five each (Fig. 45). The gas may be made in any type 
 of producer (at Messrs. Dunnachie's works, at Glenboig, 
 Wilson & Duff producers are used), and enters the kiln 
 from a flue running along the bottom or one side of the 
 flues, the hot air being supplied just above it so that 
 combustion takes place at once. Flues are arranged so 
 that the gas can be sent through the kilns in any order. 
 The flame sweeps across the kiln and through the bricks 
 stacked in it, and the products of combustion leave on the 
 other side. When at work there will always be two kilns 
 cooling off, the air passing through these on its way to 
 the kilns where burning is in progress, and being 
 heated on its way by the hot bricks ; the hot products of 
 combustion pass through two or three more kilns which 
 are filled with unburnt bricks which are thus heated ; the 
 other kilns are being charged and discharged. As sooi 
 
146 
 
 GAS KILNS. 
 
 FIG. 45. THE DUNNACHIE GAS KILN. 
 
GAS KILNS 
 
 147 
 
 as the burning is complete the valves are adjusted so that 
 the second of the two cooling-off kilns is ready for dis- 
 charging, the finished oven begins to cool off, the oven 
 which was next to the one finished becomes the 0ne in 
 which burning is taking place, and the bricks in the last 
 charged oven begin to dry. The kiln is worked con- 
 tinuously and is found very efficient. 
 
 The Davis-Colby Gas Kiln. This kiln (Fig. 46) is mainly 
 used for the magnetising-calcinatioii of hematites and 
 other ores to be subsequently subjected to magnetic 
 separation, but it might be used for the calcination of ores 
 
 FIG. 46. THE DAVIS-COLBY KILN 
 
 of any other kind. It consists of a shell of iron cased 
 with firebrick, carried on a series of iron columns, the 
 upper portion being cylindrical, the lower slightly conical. 
 Inside this is a circular wall of masonry, perforated with 
 a large number of openings so as to leave a narrow 
 annular space between it and the outer wall. In the 
 centre is a narrow cylinder of brickwork E, the walls of 
 which are also perforated with a large number of openings. 
 Thus there is in the centre a cylindrical space E ; outside 
 this is a broad annular space B, and outside this again a 
 narrow annular space 0. The ore is supplied to the space 
 B, and is withdrawn at the bottom between the columns ; 
 
148 GAS FOR ENGINES. 
 
 gas and air are supplied to the space 0, combustion takes 
 place, the products of combustion pass across B to E, and 
 thence away to the chimney F. 
 
 Kilns of this type are built up to 33ft. high and 24ft. 
 diam., with a capacity of about 8,000 cub. ft. Such a 
 kiln will burn about 800 tons of ore per week, with the 
 consumption of about 8 cwt. of coal per ton of ore. 
 
 It will be obvious that gas fuel can be used for a great 
 number of purposes, and it would serve no good purpose 
 even if it were possible to give an exhaustive list. The 
 forms of plant described can only be taken as examples, 
 and, of course, can be modified to almost any extent to 
 suit special requirements. 
 
 Gas Engines. In the conversion of heat into energy via 
 steam there are so many sources of loss that the process 
 is not likely ever to be highly efficient. This is especially 
 the case when the heat is obtained by the combustion of 
 gas not well suited for giving up its heat to water. 
 
 In gas engines the conversion is more direct ; the gas 
 is burnt in the cylinder of the engine, whence such 
 engines are often called internal-combustion engines, the 
 expansive force being used directly for the propulsion of 
 the piston. 
 
 At first these engines were made of small size and 
 worked with ordinary coal gas, but they have now been 
 made and are satisfactorily working of very large size, 
 and with every variety of gas. Gas engines are now 
 built up to 2,500 h.p., and are largely coming into use. 
 
 The subject of gas engines is far too large to be dis- 
 cussed even superficially here, as a volume would be 
 required for the purpose ; suffice it to say that they give 
 the most efficient method of utilising the energy of 
 burning gas. 
 
 As above remarked, any form of gas may be used in 
 suitably-designed engines. Coal gas was first used, and 
 is still often used for small plants, but is far too costly 
 for any other. 
 
 Gas made from coke in the Dowson producer is 
 frequently used and is often called Dowson gas, but it is 
 quite obvious that a similar gas might be made in a 
 producer of any type. Gas made from bituminous coal in 
 an ordinary producer may be used, provided the tar be 
 
GAS FOR ENGINES. 
 
 149 
 
 destroyed or removed, and gas may be made from almost 
 any organic refuse. 
 
 Mond gas is admirably suited for the purpose. In one 
 test given by Mr. Humphry, a 25 nominal horse-power 
 gas engine (Crossley Bros.), working with Mond gas, gave 
 8-71 h.p. with a consumption of 1-13 Ibs. of slack per 
 indicated horse-power hour; and in another case a simplex 
 engine of 320 h.p. used '803 Ib. of fuel per indicated 
 horse-power hour. 
 
 FIG. 47. DOWSON GAS PLANT ARRANGED FOR GAS ENGINE. 
 
 For Making Gas. 
 A Steam Boiler. 
 B Generator. 
 
 For Cleaning Gas. 
 C Hydraulic Box. 
 D Coke Scrubber. 
 E Sawdust Scrubber. 
 
 F Gasholder. 
 
 G Governing Gear. 
 
 Water gas should also be suited for the purpose, and 
 blast furnace gas is now being largely used in iron works 
 for electric lighting, driving the blowing engines, and 
 other purposes. 
 
 Conclusion. It will be seen from what has been said 
 that fuel gas can be used for almost all purposes for which 
 solid fuel can be used, and generally with considerable 
 advantage over solid fuel if the best kind of gas for the 
 particular purpose be selected. 
 
 There is very little doubt but that the near future will 
 see an enormous development in the production and use 
 of fuel gas. The electric light is largely superseding coal- 
 gas for lighting purposes, and this should lead to a large 
 utilisation of the mains for the supply of fuel gas, and 
 such a gas can also be satisfactorily used for lighting 
 purposes by the adoption of well-known methods. For 
 domestic heating, gas has undoubtedly many advantages, 
 
150 CONTROL OF PRODUCTION, 
 
 but the high cost of coal gas makes it too costly under 
 most conditions, while with a good fuel gas the cost would 
 probably be very much less than with solid fuel. 
 
 Whilst the products of combustion must always 
 escape into the air, smoke which is due to im- 
 perfect combustion should never be produced. It does 
 not, of course, follow that gaseous fuel is necessarily 
 smokeless; indeed, a tar-laden gas may produce a very 
 large amount of smoke, but even with such a gas it is 
 much easier to regulate the combustion so as to avoid 
 smoke than with solid fuel. Washed producer gas, Mond 
 gas, and water gas are, however, smokeless, and it is no 
 doubt one of these that will eventually be used, so that 
 the substitution of gaseous for solid fuel, whilst not 
 purifying the atmosphere altogether, would largely do 
 away with the smoke nuisance. There are two chief 
 characters that render the use of gaseous fuel so advan- 
 tageous in most cases : 
 
 (1) The gas can be made in any convenient place and 
 can then be distributed by means of pipes to any spot 
 where it is required with but little cost. Any one who 
 has had to deal with large works where coal is brought in 
 and distributed to a large number of furnaces will recog- 
 nise at once the enormous advantage that this gives, to 
 say nothing of the great saving of cartage and labour by 
 concentrating the fuel at one place. 
 
 (2) Gas producer plant is far less dependent on the 
 quality of the fuel than are solid fuel furnaces. Coal of 
 any sort can be used, cheap slack answering admirably, 
 provided it be not coking; indeed, strongly coking coal is 
 the only fuel quite unfit for use in gas producers. Refuse 
 of any kind can be used, and refuse destructors are 
 usually gas producers, the gas being used for boiler firing 
 or other purposes. Mr. Rowan describes an efficient 
 form of refuse destroyer which is a modified Duft 
 producer. 
 
 Control of Gas Production. Gas production, like any 
 other technical process, requires to be skilfully con- 
 trolled. Many managers seem to have the idea that 
 a gas plant once started can be left to itself, that it 
 will run automatically, and that a labourer who clears 
 the ashpit is quite capable of managing it. This is a 
 great mistake, and has led to not a few failures and to 
 
CONTROL OF PRODUCTION. 151 
 
 an enormous amount of inefficient gas production. A 
 skilled and trained man should always be in charge, 
 and in an installation of any size such a man will soon 
 save his salary, and also will produce gas of a better 
 and more uniform quality than an unskilled man can 
 possibly do. The production must be checked periodi- 
 cally by analysis of the gas as it leaves the pro- 
 ducer, and of the products of combustion as they leave 
 the furnaces. As this can only be done by a trained 
 chemist, with a laboratory in which to work, it is needless 
 to give details here. The chemist will know where he can 
 get the information, and no amount of directions will 
 enable an untrained man to make accurate determina- 
 tions ; indeed, determinations made by engineers for this 
 and similar purposes are frequently so inaccurate as to 
 be worse than useless. 
 
 The most important determination to be made in the 
 gas and in the products of combustion is carbon dioxide. 
 In the gas it should be as low as possible, under no 
 circumstances except in Mond gas rising above 4 or 5 per 
 cent., an excess, providing the producer be well designed, 
 indicating an excess of steam. In the products of 
 combustion it should be as high as possible, say 17 
 per cent., and excellent results have been obtained by 
 giving a bonus to the furnace man who keeps carbon 
 dioxide highest in his products of combustion. It is 
 evident that either incomplete combustion or excess of air 
 will lower the percentage of carbon dioxide. 
 
 Many forms of apparatus for determining the amount 
 of carbon dioxide in gas have been devised for laboratory 
 use, and are most of them quite satisfactory, though they 
 are not suitable for use by an ordinary workman. 
 
 An apparatus has been devised by Mr. G. Craig, by 
 which these determinations can be made regularly and 
 with quite sufficient accuracy for all practical purposes. 
 
 The principle on which it is based is the same as that 
 used in laboratory determinations. The gas is measured, 
 the carbon dioxide is removed by absorption, and the gas 
 is measured again, the difference being the amount of 
 carbon dioxide removed; but instead of the gas being 
 transferred to measuring and absorbing tubes, it is made 
 to flow continuously, and is measured before it enters 
 and after it leaves the absorbing vessel. (See Fig. 48.) 
 
152 
 
 CONTROL OF PRODUCTION. 
 
 The apparatus consists of two gas meters, between 
 which is placed an absorbing vessel containing soda lime, 
 the meters being filled with paraffin oil instead of with 
 water, so as to prevent the solution of the gas. 
 
 s 
 
 The gas to be tested enters meter No. 1 by the stop cock 
 J and is there measured ; it then flows by the stop cock K to 
 the absorber, downwards through the soda line, then up 
 through the escape tube and through meter No. 2, which 
 
CONTROL OF PRODUCTION. 153 
 
 records the amount of gas which escapes. The second 
 dial is graduated backwards, so that the reading gives, 
 not the amount of gas which passes, but the amount by 
 which it falls short of the 100 volumes which has passed 
 the first meter, that is, the percentage of carbon dioxide 
 present. If air be passed through, the two meters will 
 give the same reading, but if a gas containing carbon 
 dioxide be passed the reading on the second meter will 
 be lower. 
 
 When a test is to be made the gas is run through the 
 instrument till it has made about two revolutions, so as 
 to remove air and fill it with gas similar to that to be 
 tested, and the flow is stopped when the pointer of the 
 first meter is at 100. The pointer of the second meter is 
 now also brought to 100, it being made loose so that it 
 can be readily turned. The current is then started and 
 allowed to flow till the pointer on the first dial has made 
 exactly one revolution, and the pointer on the second dial 
 will indicate the percentage of carbon dioxide. 
 
 It is quite evident that the gas must be at the 
 temperature of the air. In order to insure this the gas 
 is made to flow through a cooling tube about 15ft. or 
 more in length and Jin. diam. The apparatus itself 
 should be kept in a room or in a sheltered place, so that 
 all parts of it may be at the same temperature, and it may 
 be fitted with thermometers, by which any change of 
 temperature may be observed. 
 
 The apparatus is shown placed on a metal aspirator, 
 but this is not by any means essential. A suction of 
 Jin. to Jin. of water is all that is necessary, and this can be 
 obtained by connecting the outlet with a chimney, the 
 draught from which will be sufficient to draw the gas 
 through, or any form of aspirator may be used. The 
 amount of gas passing each revolution is about '15 cub. ft., 
 and the absorbing vessel contains enough soda lime for 
 about 100 determinations. 
 
 As examples of the results obtained, the following 
 may be useful : 
 
 Per Cent. 
 
 Gas from hot blast stoves ... ... ... 17'0 
 
 16'8 
 
 16-0 
 
154 CONTROL OF PRODUCTION. 
 
 Per cent. 
 
 Blowing engine boiler (gas fired) ... ... 13*5 
 
 (air supply reduced) 14 -5 
 
 Boiler 13-2 
 
 Boiler 10-75 
 
 The brickwork of this boiler was then 
 examined and carefully pointed, and 
 the result was... ... ... ... 14 
 
 Assuming the composition of the gas to be about the 
 same as that given in the examples, it will be seen that 
 combustion in the hot-blast stoves must have been perfect, 
 and the excess of air very slight. In the boilers fired with 
 the same gas the excess of air was, of course, greater. Mr. 
 Craig has made a large number of comparative experi- 
 ments with laboratory apparatus. When every care was 
 taken in the laboratory, and the gas dried over sulphuric 
 acid before analysis, the results agreed with those given 
 by the " tester," but if the gas was not so dried the 
 laboratory results were invariably about -2 per cent, 
 lower. 
 
APPENDIX I. 
 TABLE I. 
 
 Gases Saturated with Water Vapour at 760 mm. Pressure, 
 and at Temperatures from to 99 C. 
 
 Temperature 
 t Centigrade. 
 
 Water Vapour 
 Tension in 
 Millimetres 
 of Mercury. 
 
 Grammes of 
 Water 
 Vapour 
 Absorbed bv 
 1 Cubic Metre 
 of Dry Gas 
 at O p C. when 
 Saturated at 
 t C. and 
 760 Mm. 
 
 Relative Volumes of Dry 
 Gas and Water Vapour 
 in a Saturated Mixture 
 at t C. and 760 Mm. 
 
 Total Volume 
 of Gas and 
 Water Vapour 
 resulting 
 from 
 Saturating 
 1 Cubic Metre 
 of Dry Gas at 
 and 760 Mm. 
 to t C. 
 
 Dry Gas 
 Per Cent. 
 
 Water 
 Vapour 
 Per Cent. 
 
 
 
 4-569 
 
 4-866 
 
 99-40 
 
 0-60 
 
 1-0060 
 
 1 
 
 4-909 
 
 5-231 
 
 99-36 
 
 064 
 
 1-0107 
 
 2 
 
 5-272 
 
 5-620 
 
 99-31 
 
 0-69 
 
 1-0144 
 
 3 
 
 5-658 
 
 6-035 
 
 99-26 
 
 0-74 
 
 1-0191 
 
 4 
 
 6-069 
 
 6-477 
 
 99-20 
 
 0-80 
 
 1-0228 
 
 5 
 
 6-507 
 
 6-948 
 
 99-14 
 
 0-86 
 
 1-0275 
 
 6 
 
 6-971 
 
 7-448 
 
 99-08 
 
 0-92 
 
 1-0312 
 
 7 
 
 7-466 
 
 7-983 
 
 99-02 
 
 0-98 
 
 1-0359 
 
 8 
 
 7-991 
 
 8-550 
 
 98-95 
 
 1-05 
 
 1-0407 
 
 9 
 
 8-548 
 
 9-153 
 
 98-88 
 
 1-12 
 
 1-0444 
 
 10 
 
 9-140 
 
 9-794 
 
 98-80 
 
 1-20 
 
 1-0491 
 
 11 
 
 9-767 
 
 10-47 
 
 98-71 
 
 1-29 
 
 1-0539 
 
 12 
 
 10-432 
 
 11-20 98-63 
 
 1-37 
 
 1-0587 
 
 13 
 
 11-137 
 
 11-97 98-53 
 
 1-47 
 
 1-0634 
 
 14 
 
 11-884 
 
 12-78 98-44 
 
 1-56 
 
 1-0682 
 
 15 
 
 12-674 
 
 13-64 98-33 
 
 1-67 
 
 1-0730 
 
 16 
 
 13-510 
 
 14-56 98-22 
 
 1-78 
 
 1-0778 
 
 17 
 
 14-395 
 
 15-53 98-11 
 
 1-89 
 
 1-0826 
 
 18 
 
 15-330 
 
 16-56 97-98 
 
 2-02 
 
 1-0884 
 
 19 
 
 16-319 
 
 17-66 97-85 
 
 2-15 
 
 1-0933 
 
 20 
 
 17-363 
 
 18-81 97-72 
 
 2-28 
 
 1-0981 
 
 21 
 
 18-466 
 
 20-04 
 
 97-57 
 
 2-43 
 
 1-1040 
 
 22 
 
 19-630 
 
 21-33 
 
 97-42 
 
 . 2-58 
 
 1-1099 
 
 23 
 
 20-858 
 
 22-70 
 
 97-26 
 
 2-74 
 
 1-1148 
 
 24 
 
 22-152 
 
 24-16 
 
 97-09 
 
 2-91 
 
 1-1207 
 
 25 
 
 23-517 
 
 25-69 
 
 96-91 
 
 3-09 
 
 1-1267 
 
 26 
 
 24-956 
 
 27-32 
 
 96-72 
 
 3-28 
 
 1-1327 
 
 27 
 
 26-470 
 
 29-03 96-52 
 
 3-48 
 
 1-1387 
 
 28 
 
 28-065 
 
 30-85 96-31 
 
 3-69 
 
 1-1447 
 
 29 
 
 29-744 
 
 32-77 
 
 96-09 
 
 3-91 
 
 1-1518 
 
 30 
 
 31-510 
 
 34-80 95-85 
 
 4-15 
 
 1-1578 
 
 31 
 
 33-366 
 
 36-95 95-61 
 
 4-39 
 
 1-1650 
 
156 
 
 APPENDIX 
 
 Temp. 
 C 
 
 Water Vapour. 
 
 Relative Volumes. 
 
 Total Volume. 
 
 Tension Mm. 
 
 Grammes. 
 
 Dry Gas 
 Per Cent. 
 
 Water 
 Vapour 
 Per Cent. 
 
 Gas and 
 Water 
 
 Vapour. 
 
 32 
 
 35-318 
 
 39-21 
 
 95-35 
 
 4-65 
 
 1-1722 
 
 33 
 
 37-369 
 
 41-61 
 
 95-08 
 
 4-92 
 
 1-1794 
 
 34 
 
 39523 
 
 44-14 
 
 94-80 
 
 5-20 
 
 1-1866 
 
 35 
 
 41-784 
 
 46-81 
 
 94-50 
 
 5-50 
 
 1-1939 
 
 36 
 
 44-158 
 
 49-63 
 
 94-19 
 
 5-81 
 
 1-2023 
 
 37 
 
 46-648 
 
 52-61 
 
 93-86 
 
 6-14 
 
 1-2096 
 
 38 
 
 49-259 
 
 55-76 
 
 93-52 
 
 6-48 
 
 1-2181 
 
 39 
 
 51-996 
 
 59-09 
 
 93-16 
 
 6-84 
 
 1-2266 
 
 40 
 
 54-865 
 
 62-60 
 
 92-78 
 
 7-22 
 
 1-2363 
 
 41 
 
 57-870 
 
 66-32 
 
 92-39 
 
 7-61 
 
 1-2448 
 
 42 
 
 61-017 
 
 70-24 
 
 91-97 
 
 8-03 
 
 1-2545 
 
 43 
 
 64-310 
 
 74-38 
 
 91-54 
 
 8-46 
 
 1-2643 
 
 44 
 
 67-757 
 
 78-75 
 
 91-08 
 
 8-92 
 
 1-2753 
 
 45 
 
 71-362 
 
 83-38 
 
 90-61 
 
 9-39 
 
 1-2863 
 
 46 
 
 75-131 
 
 88-26 
 
 90-11 
 
 9-89 
 
 1-2974 
 
 47 
 
 79-071 
 
 9343 
 
 89-60 
 
 10-40 
 
 1-3085 
 
 48 
 
 83-188 
 
 98-89 
 
 89-05 
 
 10-95 
 
 1-3208 
 
 49 
 
 87-488 
 
 104-67 
 
 88' 49 
 
 1151 
 
 1-3332 
 
 60 
 
 91-978 
 
 110-78 
 
 87-90 
 
 12-10 
 
 1-3468 
 
 51 
 
 96-664 
 
 117-25 
 
 87-28 
 
 12-72 
 
 1-3605 
 
 52 
 
 101-554 
 
 124-10 
 
 86-64 
 
 13-36 
 
 1-3742 
 
 53 
 
 106655 
 
 131-35 
 
 85-97 
 
 14-03 
 
 1-3892 
 
 54 
 
 111-973 
 
 139-03 
 
 85-27 
 
 14-73 
 
 1-4054 
 
 55 
 
 117-516 
 
 147-17 
 
 84-54 
 
 15-46 
 
 1-4218 
 
 56 
 
 123-292 
 
 155-80 
 
 83-78 
 
 16-22 
 
 1-4394 
 
 57 
 
 129-310 
 
 164-97 
 
 82-99 
 
 17-01 
 
 1-4571 
 
 58 
 
 135-575 
 
 174-70 
 
 82-16 
 
 17-84 
 
 1-4761 
 
 59 
 
 142-097 
 
 185-03 
 
 81-30 
 
 18-70 
 
 1-4963 
 
 60 
 
 148-885 
 
 196-02 
 
 80-41 
 
 19-59 
 
 1-5179 
 
 61 
 
 155-946 
 
 207-72 
 
 79-48 
 
 20-52 
 
 1-5396 
 
 62 
 
 163-289 
 
 220-18 
 
 78-51 
 
 21-49 
 
 1-5639 
 
 63 
 
 170-924 
 
 233-46 
 
 77-51 
 
 22-49 
 
 1-5883 
 
 64 
 
 178-858 
 
 . 247-63 
 
 76-47 
 
 23-53 
 
 1-6152 
 
 65 
 
 187-103 
 
 262-77 
 
 75-38 
 
 24-62 
 
 1-6436 
 
 66 
 
 195-666 
 
 278-97 
 
 74-25 
 
 25-75 
 
 1-6733 
 
 67 
 
 204-559 
 
 296-32 
 
 73-08 
 
 26-92 
 
 1-7044 
 
 68 
 
 213-790 
 
 314-92 
 
 71-87 
 
 28-13 
 
 1-7381 
 
 69 
 
 223-369 
 
 334-91 
 
 70-61 
 
 29-39 
 
 1-7746 
 
 70 
 
 233-308 
 
 356-41 
 
 69-30 
 
 30-70 
 
 1-8137 
 
 71 
 
 243-616 
 
 379-59 
 
 67-95 
 
 32-05 
 
 1-8556 
 
 72 
 
 254-305 
 
 404-62 
 
 66-54 
 
 33-46 
 
 1-9002 
 
 73 
 
 265-385 
 
 431-71 
 
 65-08 
 
 34-92 
 
 1-9488 
 
APPENDIX. 
 
 157 
 
 Temp. 
 C. 
 
 Water Vapour. 
 
 Relative Volumes. Total Volume. 
 
 Tension Mm. 
 
 Grammes. 
 
 Dry Gas 
 Per Cent. 
 
 Water Gas and 
 Vapour Water 
 Per Cent. Vapour. 
 
 74 
 
 276-868 
 
 461-09 
 
 63-57 
 
 36-43 
 
 2-0002 
 
 75 
 
 288-764 
 
 493-04 
 
 62-00 
 
 38-00 
 
 2-0570 
 
 76 
 
 301-086 
 
 527-88 
 
 60-38 
 
 39-62 
 
 2-1179 
 
 77 
 
 313-846 
 
 565-99 
 
 58-70 
 
 41-30 
 
 2-1843 
 
 78 
 
 327-055 
 
 607-81 
 
 56-97 
 
 43-03 
 
 2-2574 
 
 79 
 
 340-726 
 
 653-86 
 
 55-17 
 
 44-83 
 
 2-3386 
 
 80 
 
 354-873 
 
 704-79 
 
 53-31 
 
 46-69 
 
 2-4268 
 
 81 
 
 369-508 
 
 761-36 
 
 51-38 
 
 48-62 
 
 2-5245 
 
 82 
 
 384-643 
 
 824-50 
 
 49-39 
 
 50-61 
 
 2-6344 
 
 83 
 
 400-293 
 
 895-38 
 
 47-33 
 
 52-67 
 
 2-7566 
 
 84 
 
 416-472 
 
 975-45 
 
 45-20 
 
 54-80 
 
 2-8939 
 
 85 
 
 433-194 
 
 1066-5 
 
 43-00 
 
 57-00 
 
 3-0516 
 
 86 
 
 450-473 
 
 1171-0 
 
 40-73 
 
 59-27 
 
 3-2298 
 
 87 
 
 468-324 
 
 1291-9 
 
 38-38 
 
 61-62 
 
 3-4381 
 
 88 
 
 486-764 
 
 1433-4 
 
 35-95 
 
 64-05 
 
 3-6792 
 
 89 
 
 505-806 
 
 1601-0 
 
 33-45 
 
 66-55 
 
 3-9666 
 
 90 
 
 525-468 
 
 1802-7 
 
 30-86 
 
 69-14 
 
 4-3102 
 
 91 
 
 545-765 
 
 2049-7 28-19 71-81 
 
 4-7329 
 
 92 
 
 566-715 
 
 2359-1 
 
 25-43 
 
 74-57 
 
 5-2596 
 
 93 
 
 588-335 
 
 2757-5 22-59 
 
 77-41 
 
 5-9393 
 
 94 
 
 610-643 
 
 3289-6 19-65 80-35 
 
 6-8433 
 
 95 
 
 633-657 
 
 4035-4 16-62 83-38 
 
 8-1121 
 
 96 
 
 657-396 
 
 5155-2 
 
 13-50 86-50 
 
 10-017 
 
 97 
 
 681-879 
 
 7022-9 
 
 10-28 
 
 89-72 
 
 13-192 
 
 98 
 
 707-127 
 
 10760-7 
 
 6-96 
 
 93-04 
 
 19-544 
 
 99 
 
 733-160 
 
 21978-4 
 
 3-53 
 
 96-47 
 
 38-604 
 
 100 
 
 760-000 
 
 CO 
 
 
 
 CO 
 
 TABLE II. Properties of Fuel Gases. 
 
 
 
 
 
 
 Volume of Air 
 
 Lbs. per 
 
 Gas. 
 
 Formula. 
 
 Sp. Gr. 
 H = l. 
 
 Sp. Gr. 
 Air = 1. 
 
 Calorific 
 Power. 
 
 required for 
 Complete 
 
 cubic foot 
 at 760 mm. 
 
 
 
 
 
 
 Combustion. 
 
 and C. 
 
 Acetylene 
 
 C 2 H 2 
 
 13-000 
 
 0-91000 
 
 11,941 
 
 11 -90 times 
 
 0734 
 
 Atmospheric 
 
 
 
 
 
 
 
 Air 
 
 
 14-438 
 
 1 -00000 
 
 
 
 0807 
 
 Carbonic Oxide 
 
 CO 
 
 14-000 
 
 0-96710 
 
 2,430 
 
 2-38 times 
 
 0781 
 
 Carbonic 
 
 
 
 
 
 
 
 Anhydride 
 
 C0 2 
 
 22-000 
 
 1-51968 
 
 
 
 
 1227 
 
 Ethylene 
 
 C 2 H 4: 
 
 14-000 
 
 0-97840 
 
 1M43 
 
 14-28 times 
 
 0784 
 
 Hydrogen 
 
 jj 
 
 1-000 
 
 0-06926 
 
 34,180 
 
 2-38 times 
 
 0056 
 
 Methane 
 
 CH 4 
 
 8-000 
 
 0-55300 
 
 13,062 
 
 9-52 times 
 
 0447 
 
 Nitrogen 
 
 N 2 
 
 14-000 
 
 0-97010 
 
 
 
 0784 
 
 Oxygen 
 
 4. 
 
 16-000 
 
 1-10521 
 
 
 
 0893 
 
 Steam 
 
 H 2 O 
 
 9-000 
 
 0-62182 
 
 
 
 0502 
 
 
 
 
 
 
 
 
APPENDIX II. 
 
 DESCRIPTION OF RECENT GAS PRODUCERS. 
 
 IN the text it was not possible to describe more than a few 
 typical examples of producers ; so, for the further information 
 of those who are interested in the details of producers, a 
 selection has been made of what seemed the most important 
 of the forms recently patented, so that the reader 
 may be able to see how the principles which have been 
 explained, in the foregoing pages have been carried out by 
 inventors, and the direction in which improvements are being 
 sought. It is impossible to express any opinion on the 
 merits of most of the designs. Some of them have no doubt 
 been put into actual use, and their practical value thus proved 
 or disproved, but probably many of them have never gone 
 beyond the " drawing " stage. Some may contain the 
 germs of still further improvement. 
 
 In order to help the reader to find any information which 
 he may desire, a list of the producers described is given below, 
 and also a list classified according to what seems to the author 
 to be the characteristic points of each. That this arrange- 
 ment will be altogether satisfactory is not to be expected, 
 for, unfortunately, the descriptions of inventors are not 
 always clear enough to enable an accurate judgment to be 
 formed as to wherein lies the improvement. 
 
 LIST OF PRODUCERS DESCRIBED. 
 
 No. Year. Patent No. Patentee. 
 
 1 . . 1897 . . 28367 Charles Humfrey. 
 
 2 . . 1898 . . 20451 John Dymond. 
 
 3 . . 1899 . . 1574 Maurice Taylor. 
 ,4 . . 1901 . . 4522 Julius Pintsch. 
 
 5 . . 1901 . . 8449 Ludwig Mond. 
 
 6 . . 1901 . . 9377 Lucien Genty. 
 
 7 . . 1901 . . 12307 La Societe Anonyme pour le Produc- 
 
 tion et L'emploi de la Vapeur 
 Surchauffee. 
 
 8 . . 1901 . . 14183 Maurice Taylor. 
 
 9 . . 1901 . . 15646 Edward J. Duff. 
 
 10 . . 1902 . . 17265 J. A. Herrick. 
 
 11 . . 1901 . . 22016 W. J. Crossley and J. Atkinson. 
 
 12 . . 1901 . . 26330 John Robert Taylor. 
 
 13 1902 3783 F. E. Bowman, * 
 
APPENDIX. 159 
 
 No. Year. Patent No. Patentee. 
 
 14 . . 1902 . . 7613 John S. Daniels and F. L. Daniels. 
 
 15 . . 1902 . . 14893 John Fielding. 
 
 16 . . 1902 . . 15498 Walter W. Tonkin and Samuel 
 
 Puplett. 
 
 17 . . 1902 . . 18867 Charles J. Schill and H. G. Hill. 
 
 18 . . 1902 . . 18892 W. J. Crossley and Thomas Rigby. 
 
 19 . . 1902 . . 24194 W. J. Crossley and Thomas Rigby. 
 
 20 . . 1902 . . 24878 W. H. Beanes and Werner Pfleiderer 
 
 and Perkins, Ltd. 
 
 21 . . 1902 . . 25319 Joseph Emerson Dowson. 
 
 22 . . 1902 . . 25560 John Robson. 
 
 23 . . 1902 . . 26709 Alfred Wilson. 
 
 24 . . 1902 . . 27533 H. Riche. 
 
 25 . . 1902 . . 28877 G. R. Hislop. 
 
 26 .. 1903 .. 9818 Robert M. L. Rowe and R. Bickerton. 
 
 27 . . 1903 . . 12477 L. Marechal and P. Barriere. 
 
 28 .. 1903 .. 12506 La Societe Franyaise de Constructions 
 
 Mecaniques. 
 
 29 . . 1903 . . 16164 Alfred B. Duff. 
 
 30 . . 1903 . . 16263 J. R. George. 
 
 31 . . 1903 . . 25763 F. Hovine and H. Breuille. 
 
 32 ,. . . James Dunlop. 
 
 CLASSIFIED LIST. 
 
 (1) The removal of the tar from the gases is sought in 
 many of the inventions. 
 
 (a) By so arranging the upper part of the producer that 
 the coal shall be readily distilled, and the products of 
 distillation shall pass downwards into the fuel. 
 
 No. 1 (Humfrey), No. 5 (Mond), No. 6 (Genty), 
 No. 7 (Surchauffee), No. 23 (Wilson). 
 
 (b) By returning the distillates from the top of the 
 producer to the body of the fuel by means of an 
 auxiliary steam jet. 
 
 No. 2 (Dymond), No. 6 (Genty), No. 14 (Daniels), 
 No. 15 (Fielding), No. 28 (La Societe Fra^aise 
 de Construction), No. 31 (Hovine and Breuille). 
 
 (c) By passing the gas through a separate chamber filled 
 with incandescent coke. 
 
 No. 24 (Riche), No. 26 (Rowe and Bickerton). 
 
 (2) Producers in which the air and steam for combustion 
 are heated. 
 
 No. 2 (Dymond), No. 6 (Genty), No. 13 (Bowman), 
 No. 16 (Tonkin and Puplett), No. 17 (Schill and 
 
160 APPENDIX. 
 
 Hill), No. 18 (Crossley and Rigby), No. 20 (Beanes 
 and Werner), No. 21 (Dowson), Do. 22 (Robson), 
 No. 23 (Wilson), No. 25 (Hislop), No. 27 (Marechal 
 and Barriere), No. 32 (Dunlop). 
 
 (3) Producers with special arrangements for charging. 
 
 No. 12 (Taylor), No. 19 (Crossley), No. 30 
 (George). 
 
 (4) Producers with special arrangements for the supply of 
 air and steam. 
 
 No. 9 (Duff), No. 10 (Herrick), No. 21 (Dowson), 
 No. 23 (Wilson), No. 29 (Duff), No. 30 (George). 
 
 (5) Producers with special arrangements of grates. 
 
 No. 3 (Taylor), No. 7(Surchauffee),No. 11 (Crossley 
 and Atkinson), No. 13 (Bowman), No. 25 (Hislop). 
 
 (6) Producers raising their own steam. 
 
 No. 3 (Taylor), No. 6 (Genty), No. 13 (Bowman), 
 No. 16 (Tonkin and Puplett), No. 17 (Schill and 
 Hill), No. 20 (Beanes and Werner), No. 26 (Rowe 
 and Bickerton), No. 27 (Marechal and Barriere). 
 
 (7) Producers with arrangements for breaking up clinker. 
 
 No. 16 (Tonkin and Puplett), No. 20 (Beanes and 
 Werner), No. 25 (Hislop), No. 32 (Dunlop). 
 
 (8) Producers with arrangements for breaking up fuel. 
 
 No. 5 (Mond). 
 
 (9) Producers in which the air and steam is supplied at top 
 and drawn off either lower down or at bottom of producer. 
 
 No. 11 (Crossley and Atkinson), No. 21 (Dowson). 
 
 (10) Producers fed at the bottom. 
 
 No. 12 (Taylor). 
 
 (11) Producers with rotating parts. 
 
 No. 9 (Duff), No. 18 (Crossley and Rigby), No. 19 
 (Crossley), 
 
 (12) Producers arranged so as to allow easy replacement 
 of parts. 
 
 No. 8 (Taylor). 
 
 (13) Producers with regulation and purification of the gas 
 for use in gas engine. 
 
 No. 4 (Pintsch), No. 13 (Bowman), No. 32 
 (Dunlop). 
 
 (1) Humfrey's Improvements in Gas Producers. Patent 
 No. 28367 of 1897. The design shown in Fig. 1 has for its 
 object to convert the dead space below the hopper into a 
 gasifying one. The arrangement is shown applied to a Mond 
 
APPENDIX. 
 
 161 
 
 producer, in which A is the ordinary inverted hopper and C 
 a similar, but smaller sized, inverted hopper arranged below 
 the hopper A. From the upper part of the bell C one or 
 more tubes or passages D lead the gases collecting in the bell C 
 to the space E in the upper portion of the gas generator 
 above the fuel. The action of the apparatus is as follows : 
 The air and steam entering the bottom of the gas producer 
 
 FIG. 1. HUMFREY'S GAS PRODUCER. 
 
 pass nearly uniformly up through the mass of fuel, and are 
 converted into permanent gas. This gas passes partly up 
 through the bell C and partly into the space E between the 
 sides of the main hopper or receiver A and the sides of the 
 producer. The bottom of the bell C is placed so much lower 
 than the bottom of the hopper A as to make the distance 
 from the hearth of the gas producer to the surface of the 
 
162 APPENDIX. 
 
 fuel below C somewhat less than the distance from It he 
 hearth to the surface of the fuel between the walls of the 
 gas generator and the hopper of receiver. 
 
 (2) Dymond's Gas Producer. Patent No. 20451 of 1898. 
 This producer, shown in Fig. 2, has for its object to insure 
 the production of a high and uniform quality of producer or 
 water gas. It comprises a cylindrical metal shell 1, lined 
 internally with firebricks up to the normal height of the fuel. 
 Above this height is provided a fireclay lining 8, which 
 constitutes a gas superheater, and is formed with a super- 
 heating gas passage 9 that tapers in from the hopper end 3 a , 
 the contracted part being in such close proximity to the fire 
 that intense heat is retained therein. The outlet pipe 13 
 passes down to the passage 14, the gas being led up again at 
 the opposite side through another metal outlet pipe 13 a . 
 The outlet end 13 b of this pipe is connected to a vertical pipe 
 16, having at its extreme end an hydraulic valve box 17 fitted 
 with a valve 18. This valve covers the end 16 a of gas inlet 
 pipe 16, and is located within the box 17, which contains 
 water that seals the valve when the same is in its lowered 
 position, so as to then prevent escape of gas. The valve 18 
 serves to prevent back pressure when the generation of gas 
 is stopped. The hydraulic valve box 17 has a continuous 
 water supply pipe 21, and an overflow pipe 22 to keep the 
 water seal at the required height. 23 is a pipe for leading the 
 gas from the valve box 17 to a scrubber. The fuel hopper 3 
 is fitted with the two valves 24 and 25. The top of the gas 
 generator is provided with air inlet and outlet ports 35 and 
 35 a respectively, the air being directed through curved passages 
 formed by division pieces, so as to be heated by its passage 
 between the two plates 30 and 31, after which it enters the 
 vertical pipes 36 a , by which it is delivered into the ashpit 37 
 below the firebars. Each steam and air injector tube 43 is 
 provided with one or more adjustable air inlets 44. The 
 air injector is provided with a steam injector or nozzle 47. 
 
 (3) Taylor's Gas Producer. Patent No. 1574 of 1899. 
 The object of this arrangement, which is shown in Fig. 3, is 
 to provide a gas producer of small weight, and without any 
 scrubber requiring a current of water. It consists of the 
 producer A, the fuel to which is fed through a door B and 
 charging slide C. The fuel is supported by a grate secured to 
 the cleaning door D. The gas issues from the producer 
 through the pipe G, and passes through tubes H surrounded 
 
APPENDIX. 
 
 163 
 
164 
 
 APPENDIX. 
 
 by the water in a tank I, which communicates with another 
 tank having a float for maintaining the water at a constant 
 level. Under the action of the heat of the gases passing 
 through the tubes H the water in the tank I becomes con- 
 verted into steam, and when the pressure of such steam is 
 sufficient it will pass through a pipe J which opens into the 
 atmosphere ; and, as hereinafter described, this steam will 
 
 FIG. 3. TAYLOR'S GAS PRODUCER. 
 
 when requisite be carried into the furnace along with the 
 air in proper proportion. Upon leaving the tubes H the 
 gas passes by a pipe K into tubes L, which are cooled by 
 contact with the air. On leaving the tubes L the gas passes 
 by a pipe N into a cleansing chamber M containing water, 
 the pipe N terminating a little above the surface of the water ; 
 so that the gas, owing to the speed of its motion, impinges on 
 
APPENDIX. 
 
 165 
 
 such water, and ashes and dust contained in the gas are 
 retained upon or in the water, while the cooled and cleansed 
 gas passes to the engine through a pipe 0. An air-and-steam 
 supply pipe P at one end opens into a jacket Q which envelops, 
 or partly envelops, the lower part of the gas producer, and 
 opens under the grate at the base of the furnace. The pipe P 
 is contracted at its upper end R. The steam under constant 
 pressure is conveyed from the vaporiser H through the pipe 
 J, the end of which is directed towards the orifice R, so that 
 when the engine does not draw in gas from the gas producer 
 the steam escapes into the atmosphere. Upon the pipe P, 
 between the furnace of the gas producer and the point where 
 the pipe J opens, there is an air-inlet pipe S, the admission 
 of air being controlled by means of a cock T. 
 
 (4) Pintsch's Gas Producer. Patent No. 4522 of 1901. 
 In this apparatus, shown in Fig. 4, the generation of gas takes 
 place at a constant pressure, but only during the suction 
 period of the gas engine, and in exact proportion to the gas 
 feed necessary for the said engine. The arrangement, which 
 works at a pressure below that of the atmosphere, comprises 
 a gas generator E, a gas engine (not shown), a pipe A leading 
 from the gas suction chamber of the engine, and connected 
 
 C B A 
 
 FIG. 4. PINTSCH'S GENERATOR FOR SUPPLYING GAS FOR POWER PURPOSES. 
 
 immediately to a pipe B which leads through a purifier C and 
 condenser D to the top of the generator E, means for admitting 
 air and steam to the generator, and an elastic gas rarifier inserted 
 in the pipe connection between the engine and generator. 
 The generator, if water gas* is required, is provided with a 
 water tank underneath the grate F. The water in this tank 
 
 * Water gas here obviously means steam-enriched producer gas. 
 
166 APPENDIX. 
 
 being heated by the heat from the grate, and thus slowly 
 caused to vaporise, produces sufficient steam to generate 
 the necessary quantity of gas for the suction period of the 
 engine. Beneath the grate F an adjustable air inlet opening G 
 is provided, so as to admit just sufficient air to the generator 
 to retain the fire at the proper glow heat. During the suction 
 period of the gas engine sufficient air and steam will be drawn 
 by suction through the grate F of the generator to enable 
 the generation of a certain quantity of gas. The suction of 
 the engine, however, will draw the gas through the pipes B 
 and A direct to the engine, so that the gas, the generation of 
 which is dependent on the amount of suction of the engine, 
 will be immediately consumed by the latter. Since, however, 
 after the suction of the engine has ceased, a comparatively 
 small amount of gas will still be developed, which might 
 cause a dangerous increase of pressure, a pressure regulator 
 is arranged in the pipe A. This consists of a vertical pipe H 
 extending upwardly from the gas supply pipe A, and over 
 the open end of which is arranged a small bell I which is 
 pressed upwardly by means of a spring, so as to prevent the 
 atmospheric air pressure from destroying the vacuum or 
 rarification required for the proper working of the plant. 
 If now gas is drawn from the generator E during the suction 
 period of the gas engine, the suction will in a certain measure 
 influence the bell I, and pull the same slightly downwards. 
 As soon as the suction ceases, the bell will return to its normal 
 position under the influence of its spring, and in so doing will 
 draw the gas, developed in the generator E after the suction 
 period has ceased, out of the generator, thus preventing the 
 generation of gas pressure in the plant. 
 
 (5) Mond's Gas Producer. Patent No. 8449 of 1901. 
 This apparatus, shown in Fig. 5, is specially adapted for 
 converting ordinary slack into producer gases containing a 
 minimum of tarry condensible matters, and for obtaining as 
 a by-product a maximum of ammonia. The body of the 
 producer has a metal casing A lined with refractory material B, 
 and an outer metal casing C. Air is blown at D into the 
 annular space between the casings, whence it passes between 
 the firebars E into the body of fuel. A central tube I, 
 surrounded by a jacket J in which cooling water is caused to 
 circulate, extends down below the ashpit K, and has at its 
 bottom a side opening L provided with a door for removing 
 such matters as may drop down the tube. The fuel is fed 
 
APPENDIX. 
 
 167 
 
 through a hopper N and over a cone 0, filling up the bell M 
 and the space above it up nearly to the hopper. The gas 
 generated in the body of the producer passes away by the 
 
 FIG. 5. MOND'S GAS PRODUCER. 
 
 outlet P. Down the centre of the producer is passed a 
 tubular shaft Q having agitating arms R projecting from it, 
 
168 APPENDIX. 
 
 and having fixed on its upper part a wheel S which is caused 
 to revolve by a motor. Into the upper end of the shaft Q 
 enters, through a stuffing box, a steam pipe T, which terminates 
 in a nozzle U arranged to operate as an injector. Above 
 the nozzle U there are lateral holes X in the tubular shaft, 
 through which hot gas and vapours from the upper part of 
 the producer are drawn in, and these are passed through 
 the raw fuel in the bell by the action of the injector and 
 forced down into the middle of the incandescent fuel at a 
 level above the firebars, through the open lower end of the 
 shaft and openings in the tube I, in which the shaft revolves. 
 The agitators R serve to break up the fuel when it tends to 
 cake. By thus drawing a certain quantity of the hot gas 
 produced in the body of the producer through the fuel in the 
 hopper, the quantity of volatile and tarry matters in this fuel 
 is reduced before the fuel enters the body of the producer to 
 such an extent that the gas made in the body of the producer 
 is sufficiently free from tarry matters for all practical purposes, 
 while the tarry matters distilled off in the hopper are forced 
 by the steam jet in the hollow vertical shaft right through 
 the mass of incandescent fuel inside the producer, and are 
 thus converted into permanent gas. 
 
 (6) Genty's Gas Producer. Patent No. 9377 of 1901. 
 The principal object of this design (Fig. 6) is to obviate the 
 disadvantages met in connecting gas engines directly to gas 
 producers. The lower portion of the producer comprises 
 the hearth A and the shaft B, surmounted by a concentric 
 vertical retort C heated on its outer surface by the heat of 
 the escaping gas. The hearth A consists of a central conical 
 sole surrounded by an annular grate D. The hearth is enclosed 
 in a chamber supporting the producer, into which enters a 
 current of hot air and steam coming from a regenerator. 
 The combustion zone is situated immediately above the hearth, 
 and the products distilling off from the charge of fresh fuel 
 at the top of the producer are conducted by a pipe E to the 
 part of the combustion zone where the temperature is greatest. 
 The gases are formed above the combustion zone. Higher 
 up in the gas generator is a zone in which the fuel is heated 
 by the radiated heat. This latter zone, and the whole 
 upper part of the producer are surrounded by a boiler F, 
 the water in which absorbs the heat which escapes through the 
 walls of the producer. The produced gases circulate through 
 the annular flue G, and then escape by a pipe H into the 
 
APPENDIX. 
 
 169 
 
170 
 
 APPENDIX. 
 
 regenerator. A suction fan I is situated in the pipe E to 
 assist in drawing from the retort all the volatile matter, 
 and forces these products into the hottest zone of the pro- 
 ducer. The tarry products are decomposed, and give a 
 deposit of carbon which burns on the hearth. The steam 
 and other gaseous products, on meeting the gaseous current 
 produced by the action of the gas producer, undergo reduction 
 under the action of the red-hot fuel. The hot gases from the 
 producer enter the regenerator J at its upper part, and 
 heats the air that is supplied to the hearth of the producer, 
 and also the water contained in a small boiler for producing 
 the steam required for the working of the producer. This 
 boiler is constituted by an externally-ribbed tube L in the 
 centre of the regenerator. On leaving the regenerator the 
 producer gases enter scrubbers M, and after purification 
 pass to an aspirating arrangement consisting of a fan N 
 supplying a constant volume of air. 
 
 21 
 
 FlG. 7. SURCHAUFFEE GAS PRODUCER. 
 
APPENDIX. 171 
 
 (7) Surchauffee Gas Producer. Patent No. 12307 of 1901. 
 This apparatus (Fig. 7) has for its object to obtain a uniform 
 composition of the gas produced and a uniform temperature 
 thereof, while insuring a maximum production of gas with an 
 apparatus of comparatively small dimensions. It consists of 
 a casing 1 to receive the fuel, and having, as shown, the form 
 of two truncated cones meeting at their smaller ends. The 
 casing 1 has at the top a number of charging inlets 2 closed 
 by covers 23. The air necessary for the gasifying of the 
 fuel is blown in by the central pipe 3 following the direction 
 of the arrows 4 ; it then passes through the fuel, and burns 
 in the zone 5, while the products of distillation from the 
 upper layers 6 of the fuel escape by openings 7 formed in the 
 casing 8, which surrounds the central pipe 3. These products, 
 then following the direction of the arrows 9, pass through 
 the combustion zone 5, where they are decomposed, and 
 then pass as indicated by the arrows 10 into the space 11, 
 mixed with the gases of partial combustion. The gaseous 
 mixture thus formed heats the fuel 12, and escapes, with a 
 composition and at a temperature practically uniform by 
 the outlet 13. The firegrate 16 is provided at its centre 
 with an opening which can be partially closed by a conical 
 shaking grate, which is operated by means of a lever 18. 
 The air supply pipe has at its top a lid 21, which serves at 
 starting for the kindling of the fuel by petroleum or otherwise. 
 
 (8) Taylor's Gas Producer. Patent No. 14183 of 1901. 
 The object of this apparatus (Fig. 8) is to provide means 
 whereby the refractory material and metallic parts can be 
 readily and quickly renewed without disturbing the joints. 
 It consists of a cylindrical chamber A provided with a cover B 
 carrying the charging hopper C, and a supporting cylindrical 
 base D containing the incandescent fuel chamber S. The 
 metal ring E enclosing the refractory material F, forming 
 the lower part of the chamber A, fits in a bored opening in 
 the top of the cylindrical base D. The air and steam required 
 for the production of the gas enter the ashpit G through a 
 passage H communicating with the annular space J between 
 a ring K and the lower part of the ring E which it surrounds, 
 the ring K being held in position by screws M. The bottom 
 of the ring E is closed by a washer N resting on rods which 
 are slightly curved. The refractory material F at the lower 
 part of the chamber S rests on the washer N, and fits inside 
 the ring E. A door R permits of the refractory material F, 
 
172 
 
 APPENDIX. 
 
 ring K, and washer N being introduced into or removed from 
 the producer without it being necessary to take down any 
 other part. The refractory material S and ring E can be 
 easily removed by removing the chamber A. When the 
 
 FIG. 8. TAYLOR'S GAS PRODUCER. 
 
 part E has been renewed the refractory material S is placed 
 in position, and the chamber or casing A is again bolted to 
 the supporting base D, the annular space T is filled with 
 grouting or a cement of refractory earth, so that the joint 
 between the parts S, A, and E is thus secured. 
 
 (9) Duffs Gas Producer, Patent No. 15646 of 1901. 
 This producer, which is shown in Fig. 9, is more especially 
 applicable where town's refuse is used as fuel, and consists 
 of a firebrick-lined casing A fixed at its lower end to a 
 depending tapered metal piece B which dips into a water 
 seal C. The piece B is provided with rollers B x arranged to 
 travel on a circular rail D. With this arrangement the 
 firebrick casing A, with its depending piece B, can thus be 
 turned round, the parts being rotated by means of a driving 
 pinion E and circular toothed rack E x . The casing A is 
 
APPENDIX. 
 
 173 
 
 provided with a metal cover G having an inner lining G l of 
 firebrick, the cover being fixed to the charging platform H, 
 so that it does not interfere with the rotation of the vertical 
 
 FIG. 9. DUFF'S GAS PRODUCER. 
 
 casing A. The cover G is provided with a depending spigot 
 part G 2 which dips into a liquid J in a trough J 15 thus forming 
 an effective seal. A fuel charging box K is fitted to an inlet 
 
174 APPENDIX. 
 
 K!, the opening at the bottom of the box being controlled 
 by a weighted valve K 2 . The gas escapes from the producer 
 by an outlet L. Air is led from a blowing apparatus to the 
 fuel bed by pipes M connected to a stand pipe N. On this 
 stand pipe is mounted a cone-shaped air-distributing nozzle P, 
 consisting of a series of sloping annular plates P 15 P 2 , P 3 , P 4 , 
 overlapping each other, curved vanes Q being arranged all 
 round the annular openings R thus left between the plates. 
 The bottom ring P 4 is fitted to a perforated plate S fixed to 
 the stand pipe flange N. The blower piece P is surmounted 
 by a cap or cover P 5 . The action of the apparatus is as 
 follows : After the producer has been charged with fuel, 
 the vertical shell A is turned slowly round, and this slow 
 rotating movement, combined with the polygonal contour 
 of the lining A 1 of the shell, has the effect of twisting the 
 fuel bed so as thereby to break it open, and thus feed the fuel 
 down to the air-distributing nozzle P in an open condition. 
 The air issuing from the blower piece P is thus allowed to 
 distribute itself freely and uniformly through the fuel. The 
 curved vanes Q on the blower piece P act as baffles, and 
 impart a swirling or circular movement to the air as it issues 
 from the blower piece, and thereby prevents the issuing air 
 from being too directly and forcibly blown upon the lining A 1 
 of the producer, and also prevents the formation of adhering 
 clinker, as well as the overheating of the shell plates. 
 
 (10) Herrick's Gas Producer. Patent No. 17265 of 1902. 
 The object of this design, shown in Fig. 10, is to provide for 
 supplying to the mass of fuel air in large volume, but so 
 uniformly distributed throughout the mass as to have no 
 disrupting action upon any portion of the same by reason of 
 its pressure, to regulate the blast as desired, and to prevent 
 any clogging of the blast openings. Projecting through the 
 lower portion of the casing of the producer are a series of 
 tuyere boxes 4 having straight sides and open bottoms, and 
 meeting at the centre, where they are supported by a hollow 
 casing 5. This hollow casing is connected to an injector 7, 
 whereby air is blown into the hollow tuyere boxes. The sides 
 of these tuyere boxes are provided with slots for the escape 
 of the air. The effective area of these slots can be varied by 
 adjustment of sliding dampers 9. Each of the tuyere boxes 
 has at the outer end a door 10 for cleaning purposes, and 
 the lower portion of the casing of the producer has alongside 
 of each tuyere box a socket 11 for the reception of a firebrick 
 
.APPENDIX. 
 
 175 
 
 12, on the removal of which plugs access may be had to the 
 outer side of the tuyere boxes and their dampers for the 
 purpose of removing ashes or cinders. The tuyere boxes 
 being embedded in the ashes in the lower portion of the 
 producer, these ashes close in beneath the tuyere boxes, so 
 that no air can escape from either box without entering the 
 mass of ashes, and then rising through the same into the 
 mass of incandescent fuel above, the uniform distribution of 
 
 
 FIG. 10. HERRICK'S GAS PRODUCER. 
 
 the air escape opening of the tuyere boxes throughout the 
 mass of ashes insuring a thorough dissemination of the air 
 throughout all portions of the mass of fuel in the producer 
 without the employment of a powerful blast ; hence air in 
 large volume can be passed through the producer, and corre- 
 spondingly large volumes of gas can be produced without 
 the employment of any such pressure as will tend to disrupt 
 the mass of incandescent fuel. 
 
176 
 
 APPENDIX. 
 
 (11) Crosslcy and Atkinson's Gas Producer. Patent No. 
 22016 of 1901. This producer (Fig. 11) has been designed 
 for making gas of a somewhat low calorific value, such as is 
 commonly used for driving gas engines and for heating 
 purposes generally. An essential feature of the producer 
 is that the fuel is introduced at the top, and is continuously 
 
 consumed downwards, the air for supporting combustion 
 being introduced at the top and the gases taken away from the 
 bottom. The producer consists of a casing A lined with 
 firebrick B. At the bottom the lining B is supported on a 
 flat iron ring D, and under this iron ring is a revolving ball- 
 
APPENDIX. 177 
 
 bearing grate E, having ribs F on its upper side projecting 
 into the fuel bed, a space being left between the ring D and 
 the grate E for the passage of the gases and the ashes. At the 
 lower portion G of the producer is a water lute which assists 
 in keeping the grate E and the ring D from being overheated, 
 allowing the removal of the ashes by means of the opening H, 
 which is open to the outside without interfering with the 
 continuous working. The fuel is introduced by means of a 
 bell I and hopper J. The air is introduced at the lower part 
 of an annular space K contained between the producer 
 shell A and an outer shell L, so as to pick up heat as it rises 
 to the top of this space. The bell I defines the active depth 
 of the fuel, and the distance from its lower edge to the grate 
 level requires to be suitable for the fuel used and for the size 
 of the producer. It may be filled with fuel so as to hold a 
 reserve, and as the fuel burns away it drops out of the bell 
 into the producer itself. As there is no material supply of 
 air to the fuel in the bell, it cannot burn in the bell, but can 
 only commence to burn after passing out of the lower end. 
 In the top plate there are a number of poker holes M closed 
 normally with taper plugs. The gas passes away by the 
 pipe N. 
 
 (12) Taylor's Gas Producer. Patent No. 26330 of 1901. 
 This producer, shown in Fig. 12, has for its object to produce 
 a gas which shall be free of unstable constituents requiring 
 subsequent removal. The walls 1 of the generator are con- 
 tracted near the bottom, so as to permit the incandescent 
 coke to be bridged over above the stokers to thereby support 
 itself. 2 are hoppers for introducing the initial charge of 
 fuel. 4 4 are the uptakes leading to the gas main 5. 6 is 
 a conduit leading to a regenerative furnace for utilising the 
 gas produced. 7 7 are the feeding devices for introducing 
 the fuel under the bed of incandescent coke contained in 
 the generator. 8 8 are steam pipes, and 9 9 are air openings, 
 the parts being so arranged that the issuing steam forces into 
 the lower parts of the generator commingled air and steam. 
 The underfeed stoker comprises the Archimedean screw 10, 
 the coal reservoir 11, over the sides of which the coal is 
 elevated by the screw, an air chamber 12 surrounding the 
 magazine, and supplied with a forced draught, tuyere blocks 
 13 at the sides of the fuel magazine, and connected with the 
 air chamber 12, and openings 14 in the tuyere blocks, 
 through which air is ejected therefrom into the generat- 
 
178 
 
 APPENDIX. 
 
 ing chamber. These stokers are arranged end to end, 
 and are placed near an abutment 15 located so as to 
 discharge the green fuel above the point where the 
 air and steam enter through the nozzles 8 and 9. 16 16 are 
 
 water-sealed ashpits, into which the incombustible ash 
 or residue descends from the generating chamber. In the 
 operation of the device wood kindlings are first introduced 
 through the hoppers 2 2, and on top of them coke is fed to 
 
APPENDIX. 179 
 
 the desired depth. The fire being lighted, and the coke 
 brought to the required condition of incandescence, the 
 stokers are started and green coal is continuously fed into 
 the generator under the incandescent coke. This fuel, as 
 it is fed upward, is converted into coke by the distillation of 
 its hydrocarbon constituents, which, in the presence of the 
 air issuing through the air openings 14, are decomposed, 
 forming carbonic acid gas and hydrogen. The carbonic acid 
 gas passing upward through the incandescent body of coke 
 above it is converted into carbonic oxide gas before it leaves 
 the generator. The water contained in the coal is, like the 
 steam introduced through the nozzle 8, decomposed, pro- 
 ducing hydrogen gas and oxygen, the latter serving to facilitate 
 the oxidising operations which take place in the generator. 
 The fresh coke overflows from the stoker, and passes down 
 at the sides of the abutment 15, where it meets the incoming 
 air and steam introduced through the nozzles 8 and 9. In 
 the presence of the free oxygen combustion of the coke ensues 
 and carbonic acid gas is produced, which passes upward 
 through the incandescent body of coke above it, and is 
 converted into carbonic oxide gas. The hydrogen which 
 results from the decomposition of the steam passes up through 
 the incandescent coke unchanged owing to the limited air 
 supply. 
 
 (13) Bowman's Gas Producer. Patent No. 3783 of 1902. 
 This apparatus (Fig. 13) comprises a generator 1, lined with 
 fireclay, and provided with an ashpit 3. In this ashpit is 
 mounted a furnace grate 5, the position of which is controlled 
 by a hand lever 7. Below the firebrick lining is fitted a 
 coil 9, the ends of which are carried upward, one into the steam 
 space and the other into the water space of a small boiler 10 
 provided with field tubes 11, which are suspended in a space 
 heated by the furnace. The boiler is supplied with water 
 through a feed pipe 12, while the surplus water passes away 
 through a tube 13. To the top of the generator a vessel 14 
 is fitted, and at the top of this vessel is secured a hopper 15 
 for the supply of fuel. A ring of fine gauze 16 is fitted 
 between the firebrick lining and vessel 14 to prevent coal 
 dust, &c., passing out with the products of combustion. 
 The air for combustion is admitted at the bottom of a chamber 
 17 formed round the exhaust pipe 18 of the gas engine, 
 gills 20 being fixed upon the pipe to form baffles, and cause 
 the air to make a tortuous passage, and so absorb the heat ; 
 
180 
 
 APPENDIX. 
 
 the hot air from this chamber 17 is conducted by a pipe 21 
 to the steam space of the boiler, and this steam space 
 is also connected by a pipe 22, controlled by a damper 
 34, to the chamber 3. The space below the boiler at 
 the upper part of the generator is connected to a 
 
 pipe 23, the upper part of which forms a chimney 
 when a damper 24 is opened, while the lower end 
 of the pipe 23 enters a vessel 25 in which is fitted a pipe 26 
 with a bell-mouthed opening at the bottom, which dips 
 
APPENDIX. 181 
 
 slightly into water contained in a tank 27 supporting a scrubber 
 28, the bottom of which consists of a perforated plate 29. 
 The scrubber is provided with a central pipe 30, which passes 
 through the water tank 27 into an expansion chamber 31 
 connected by a pipe 32 to the cylinder 19 of the gas engine. 
 When the fire is lighted upon the grate 5 it requires the aid 
 of a blower to start the fire and raise a little steam, the 
 damper 24 in the pipe 23 being opened to the chimney, and 
 the damper 34 in the pipe 22 being closed. The use of the 
 coiled pipe 9 forming an auxiliary boiler enables steam to be 
 raised more readily. When the gas produced is rich enough 
 to burn, which can be tested by opening a valve 33 in the 
 vessel 14 and applying a light, the valve 24 is closed and 
 the gas blown through the scrubber to a tap 35 on the pipe 32. 
 When the gas burns here the gas valve on the engine is opened 
 and the flywheel is turned to start the engine. As soon as 
 the engine is properly started, damper 34 in the pipe 22 is 
 opened, and the engine aspirates the gas from the generator 
 and maintains combustion therein. 
 
 (14) Daniels' Gas Producer. Patent No. 7613 of 1902. 
 The main features of the design shown in Fig. 14 are the 
 means provided for collecting and utilising the distilled and 
 condensible gases from the upper portion of the producer, 
 and the method of constructing and arranging the firebars 
 and other fittings. At the upper end of the casing A is a 
 feeding hopper, the inner branch F of which projects below 
 the upper end G of the interior chamber E so as to form an 
 annular collecting head from which the distilled gases and 
 vapours escape by means of an opening H 1} which leads into 
 a conduit passage H. The lower end of this collecting con- 
 duit H is joined to a feeder branch K which delivers the 
 distillates and gases to the lower portion of the firegrate 
 within the zone of combustion. This branch K is formed 
 with slots through which the distillates are delivered, and 
 through which the steam for decomposition in the interior 
 of the gas producer passes. The branch K also forms a 
 support for the firebars. Steam is introduced through a nozzle 
 J for the creation of an induced draught in the conduit H. 
 Within the interior of the producer is arranged the projecting 
 ring-like collector D for leading to the gas outlet passage. 
 The firegrate is formed of rocking bars L and O, carried on 
 central spindles M, operated by hand levers N. The rocking 
 bars I are made to intermesh on their inner ends with pro- 
 jecting bars Q formed upon the bearer member K. 
 
182 
 
 APPENDIX. 
 
 FIG. 14. DANIEL'S GAS PRODTJCKR. 
 
 (15) Fielding's Gas Producer. Patent No. 14893 of 1902. 
 The object of this design, shown in Fig. 15, is to enable 
 gas producers to be worked with open tops into which the 
 fuel may be charged at all times, and so that at any time 
 pokers or stirrers may be introduced into the centre of the 
 fire. A is a hopper into which the coal is fed, B is an enlarged 
 extension forming a feed chamber through which the coal 
 descends into the body of the fire C. D is an annular space 
 in connection with which there is fitted an outlet E through 
 which are drawn off the vapours formed by the heating of 
 the coal in the feed chamber B. F is a steam injector which 
 draws off the vapours and discharges them into the body 
 of the fire at G. Since a slight vacuum will be produced in 
 
APPENDIX. 
 
 183 
 
 the annular space D, there will be a slight suction of air 
 through the coal in the hopper A, and this air will be 
 delivered with the vapours into the body of the fire at the 
 
 FIG. 15. FIELDING'S GAS PRODUCER. 
 
 point G. H is the ordinary air blast supply, for support- 
 ing combustion, the air being supplied either by an injector 
 or by a fan. I is the gas outlet. 
 
 (16) Tonkin & Puplctt's Gas Producer, Patent No. 15498 
 of 1902. This producer, shown in Fig. 16, comprises a cham- 
 ber B provided at the top with a fuel hopper C, the latter 
 being fitted with an internal bell valve E. Below the hopper 
 is a conical retort F projecting into the chamber B, and 
 provided with ribs. The bell valve E is attached to a rod G. 
 This rod projects downwards into the retort, and is used as 
 
184 
 
 APPENDIX. 
 
 a poker E 18 The hot gas leaving the producer through the 
 passage A is transferred to the cold incoming air blast, and 
 cooled by means of the heat interchanger K, in which the 
 
 Xs 
 
 FIG. 16. TONKIN & PUPLETT'S GAS PRODUCER. 
 
APPENDIX. 185 
 
 cold air and hot gases pass in opposite directions through the 
 two flues K! and K 2 . This interchanger consists of a 
 rectangular chamber K 3 , the sides of which are provided 
 with projecting ribs. The upper end of this chamber is 
 closed by a cover, and is enclosed along with the projecting 
 ribs within walls forming two flues K 2 , down which the hot 
 gas passes. A vertical pipe L extends nearly to the top of 
 the chamber K 3 , and communicates at the bottom with the 
 passage L 1} which conveys the hot air down to the annular 
 passage P 2 . The passages N x formed in the base of the heat 
 interchanger communicate between the air inlet N and the 
 lower part of the inside flues Kj. Similar passages O l convey 
 the cool gas from the flues K 2 to the gas outlet pipe 0. The 
 heated air blast is introduced through the nozzles P 3 . A 
 conical ring Q is fitted at the bottom of the producer, to 
 which is attached an extension ring R which dips into the 
 water seal S. In the upper part of the conical ring Q is an 
 opening extending all round the chamber. Through this 
 opening steam is introduced which rises up the inside of the 
 walls of the chamber B, and cools the fuel next to the brick- 
 work, and so breaks up the clinker. A second annular air 
 passage R x is formed between the two rings Q and R, through 
 which air is supplied in order to burn any fuel that may have 
 escaped the main hot-air blast. Poking devices T x , which move 
 in a curved path, are fitted to the shafts T. To obtain a supply 
 of steam for working the air blast, water is supplied to the 
 tubes X, arranged in openings in the brickwork surrounding 
 the chamber B. This brickwork, being at a high temperature, 
 furnishes the necessary heat for generating the steam. 
 
 (17) Schill & Hill's Gas Producer. Patent No. 18867 of 
 1902. This producer, shown in Fig. 17, is particularly 
 applicable to small installations. The top of the generator 
 is equipped with a steam-raising and heat-storing device 
 consisting of a mass of cast iron 5, within which a tubular 
 coil of wrought-iron pipe 6 is embedded, and the mass of 
 iron is perforated at 7 to allow of the passage of the products 
 of combustion. The coiled pipe 6 is connected by means of 
 a branch pipe 8 with a water supply under pressure. The 
 delivery end of the coiled pipe 6 is connected to a steam 
 drum 9, fitted with a regulating valve 12 which controls the 
 delivery of steam through a pipe 13 to a jet 14. Immediately 
 above the steam nozzle 14, and within the chimney 15, is 
 fitted a movable valve 16. A gas holder is provided to 
 
186 
 
 APPENDIX. 
 
 receive the gas as produced, and the top of the gas holder 
 is connected by mechanism with the valve 16 in such a way 
 that when the holder is raised to its utmost limit the valve 
 is opened, and when it has sunk to its predetermined limit 
 the valve is closed, both movements being automatic. The 
 lower part of the generator is provided with an outlet for 
 clinker or ashes, this being sealed by a water lute 20. The 
 air inlet 21 is provided with a clack valve 22 opening inwards, 
 and from the annular chamber 21 the air passes downward 
 
 FIG. 17. SCHILL & HILL'S GAS PRODUCER. 
 
 through the curved pipes 23, becoming highly heated by the 
 products of combustion from the generator. The heated air 
 issuing from the pipes 23 enters an annular chamber 24, 
 and flows downward through a pipe 25, and enters the 
 generator through a series of radial openings 26 connected 
 by an annular passage 27. There is an outlet 28 for gas 
 which passes a non-return seal (not shown) on its way to the 
 
APPENDIX. 
 
 187 
 
 gas holder. There is also a supplementary air supply 
 admitted through a clack valve opening inwards to an annular 
 passage 30, whence it passes through radial passages 31 to 
 the interior of the generator. 
 
 (18) Crosslcy & Ruby's Gas Producer. Patent No. 18892 
 of 1902. This producer (Fig. 18) consists of a casing A lined 
 with firebricks B placed inside a casing C which is carried 
 lower than the casing A and enclosed so as to form a water 
 lute. The top of the producer is arranged with a central 
 
 FIG. 18. CROSSLEY & RIGBY'S GAS PRODUCER. 
 
 bell E for collecting the gases. The fuel is fed into the 
 producer by means of charging hoppers G arranged to drop 
 the fuel into the space between the outside of the hanging 
 bell and the lining of producer. A reservoir of fuel is so 
 obtained, and being in contact with the outside of the hot 
 collecting pipe, the fuel is heated during its descent to the 
 actual working level of producer. The brickwork lining of 
 the casing rests upon a plate fixed to the bottom of the casing, 
 
 or 
 
188 APPENDIX. 
 
 and a few inches below this plate is fixed the revolving table M, 
 in which is fixed the firegrate N. This table is somewhat 
 larger than the diameter of the brickwork, and is supported 
 upon balls P, which enable it to be easily moved. The air, 
 or air and steam which is passed into the producer, is super- 
 heated in the annular spaces between the two casings, and is 
 brought by the pipe Y into the cylinder previous to entering 
 the fuel bed. On the upper portion of the cylinder are 
 arranged two concentric cylindrical vertical rings T and T 15 
 which project upwards a few inches, and the space between 
 the rings is filled with sand. On the bottom side of the 
 firegrate table is arranged the cylindrical vertical ring T 2 , 
 which is immersed in the sand contained in the space between 
 the lower rings, and forms a sand seal which is not affected 
 by the heat of the fire. As the lower portion of the cylinder 
 is sealed in water, any air, or air and steam, passed into the 
 cylinder can only escape upwards. The grate is arranged 
 in the form of single parallel firebars, secured so as to revolve 
 with the table. The grate being flat, and the gas being taken 
 away in a central position from the upper portion of the 
 producer, the tendency is for the bulk of the air, or air and 
 steam, to pass upwards more through the middle portion of 
 the fuel than the outer diameter next the brickwork. In 
 this way less clinker is produced near the lining of the producer, 
 and as a consequence a poorer class of fuel can be used than 
 is usual, and a gas of high heating power is obtained. 
 
 (19) Crosslcy & Rigby's Gas Producer. Patent No. 24194 
 of 1902. This arrangement, shown in Fig. 19, has been 
 designed with a view to producing gas from bituminous coals 
 free from objectionable tarry vapours. The fuel is distilled 
 in the retorts A by means of the sensible heat of the gases 
 and the radiant heat of the fuel in the producer, the caked 
 residue being afterwards fed into the producer and consumed 
 there. The retorts are arranged with hollow, spiral castings 
 B, which close the bottom end. Screw tackle is arranged so 
 that the casting B may be rotated independently of the screw. 
 When charging a retort the valve face of the casting B is 
 tightened in its place, and fuel admitted into the retort is 
 projected downwards into the spaces between the spirals by 
 turning the capstan C in the right direction for this operation. 
 When discharging a retort the casting B, in the first place, is 
 lowered a distance by means of the tackle, and the capstan, 
 in the second place, is turned in the same direction to that 
 
APPENDIX. 
 
 189 
 
 when charging. The coked fuel in the retort A is thus 
 projected downwards, and broken up by the spirals. The 
 volatile gases given off from the green coal in the retorts A is 
 conducted by way of the pipes E and F to the lower portion 
 of the fuel bed of the producer. When a charge has been 
 completely distilled in a retort the gas outlet therefrom is 
 
 FIG. 19. CROSSLEY'S AND KIGBY'S GAS PRODUCER FOR BITUMINOUS COAL. 
 
 shut off temporarily by means of the dampers G. The coke 
 or residue is broken up into suitable sections by the spiral D, 
 and is dropped out of the retort into the producer. A fresh 
 charge is fed into the retort through the door, which is then 
 secured, and the damper G again opened. The fuel, after 
 passing through the retorts, will not cake a second time, and is 
 
190 APPENDIX. 
 
 thus very suitable for use in the producer, and the gas pro- 
 duced is more uniform than that obtained in the usual manner. 
 The firegrate T is of the rotary type, and is carried by a ring 
 K, the lower portion of which is immersed in water. In 
 addition, a second ring M is arranged concentrically inside the 
 other, and is also immersed in the water. The upper portion 
 of the inner ring is arranged with an annular groove N, which 
 contains sand or water. On the underside of the firebars is 
 arranged the vertical ring P, which is immersed in the sand 
 or water. Connection is made to the inner ring by the pipe S 
 passing through the outer chamber. The air and steam 
 necessary for the gasification of the fuel is contained in the 
 outer chamber, and the volatile gases and vapours are led 
 from the retort to the inner chamber M. They are kept 
 separate, but enter the fire through the same bars. 
 
 (20) Beancs & Werner's Gas Producer. Patent No. 24878 of 
 1902. The object of this design (shown in Fig. 20) is (1) to 
 improve the construction, working, and durability of producers, 
 (2) to equalise the temperature of the gas passing therefrom, 
 and (3) to utilise waste or surplus heat to increase the quantity 
 and improve the quality of the gas produced. To admit of 
 ashes and clinker being broken up and removed, the lower end 
 of the producer is provided with a hopper-shaped metallic ring 
 2, the lower end of which is provided with a centrally arranged 
 tubular extension 6 that dips into a water seal 7. The ring 2 
 with its extension 6 is provided with lateral wings 9 that 
 serve to divide the air space below the ring and above the 
 water seal into two portions, one of which, viz., 10, forms a 
 closed air chamber into which air, or air and steam, is or are 
 led through passages 11, and the other of which, viz., 10 a , is 
 open to the external atmosphere through a large opening 
 10 b in the front of the producer. A tubular carrier 12 that 
 dips into the water seal 7 is supported by a pair of bent 
 lever arms 13 fixed to a rock shaft 14, the shaft being provided 
 with a lever 16 capable of being oscillated. Held by the 
 tubular carrier 12 is a hollow metal fuel support 17 provided 
 around the side with ports. The portion of the tubular 
 extension 6 forming part of the closed air chamber 10 is 
 formed with openings 18, through which air can pass into the 
 fuel chamber 1. By the construction described, the most 
 active combustion, it is claimed, will take place in the centre 
 of the fuel, the rapid destruction of the wall of the producer 
 will be prevented, and any clinker formed will rest upon the 
 
APPENDIX. 
 
 191 
 
 metal portions at the bottom of the fuel chamber. When it 
 is desired to break up clinker resting on the ring 2 and 
 central fuel support 17, the rock shaft 14 is oscillated by 
 means of the hand lever 16. By turning the rock shaft to 
 a greater extent, the tubular carrier and fuel support can be 
 caused to move downward out of the tubular extension 6, 
 and into the water seal, so as to permit ashes and clinker to 
 
 FIG. 20. BEANES & WERNER'S GAS PRODUCER. 
 
 fall freely into the receptacle below. The fuel above the 
 ashes and clinker is at this time supported by a temporary 
 grate composed of metal bars 20 that are inserted across the 
 lower part of the fuel chamber 2. After the ashes and clinker 
 have been removed, the tubular carrier is returned to its 
 normal position, and the temporary grate bars withdrawn. 
 To enable the gas to pass away from the gas producer at an 
 
192 
 
 APPENDIX. 
 
 approximately uniform temperature, the upper part is con- 
 structed with a regenerator chamber 34 that communicates 
 through openings 35 with the upper part of the fuel chamber, 
 and is provided with brickwork arranged chequerwise. The 
 regenerator chamber is provided with pipes 40, through which 
 air is led on its way to the closed air chamber 10 at the bottom 
 of the producer, so that excess of heat from the escaping gas 
 can be utilised to heat the air on its way to the fuel chamber 1 . 
 The regenerator chamber may also be provided with pipes 40 a 
 into which a small stream of water is led and converted by 
 surplus heat into steam that is mixed with the air and led 
 to the fuel chamber to increase the quantity and quality of 
 the resulting gas. 
 
 (21) Dowson's Gas Generator. Patent No. 25319 of 1902. 
 In this apparatus air, or steam and air, are made to enter 
 the gas generator at or near the top and the bottom thereof, 
 
 FIG. 21. FIG. 21A. 
 
 Dowsox's GAS GEN* BATOR. 
 
APPENDIX. 193 
 
 there being a gas outlet about half-way up the generator, 
 through which the gases from the upper and lower parts of 
 the generator pass out. In this way the fuel in the lower 
 part of the generator is worked by an up draught, while that 
 in the upper part of the generator is worked by a down draught. 
 The gases formed in the lower and upper parts of the generator 
 then pass outwards through the outlet. This way of working 
 a gas generator is, the inventor claims, especially suitable 
 where the gas is made from bituminous coal or other fuels 
 containing hydrocarbons, as the portion of the fuel which is 
 not converted into gas in the upper part of the generator is 
 made into gas as and when it reaches the lower part thereof. 
 The air required for producing gas in the generator is forced 
 into it by a pump or blower, a jet of steam, or any other 
 suitable means. The generator may be surrounded by an 
 air jacket, so that the air to be used may be heated before it 
 comes in contact with the fuel. In the accompanying 
 illustrations Fig. 21 represents one arrangement of gas 
 generator, and Fig. 2lA another arrangement. In Fig. 21 there 
 is an outer casing A, lined with firebricks B, feeding 
 hopper C, grate D, gas outlet E, and iniets F F for air or 
 steam, and air door G. In Fig. 2lA there is an inner casing A 
 and outer casing A^ with air space between the two casings. 
 There is a firebrick lining B, feeding hopper C, grate D, gas 
 outlet E, and inlets F F for air or steam, and air doors G. 
 Any suitable feeding hopper or arrangement of firegrate 
 may be used. 
 
 (22) Robson's Gas Producer. Patent No. 25560 of 1902. 
 This producer is shown in Fig. 22. Around the lower portion 
 of the coal-feeding hopper 6 is cast an air jacket 13 to which 
 a fan 14 is connected by duct 15. The jacket 13 is also 
 intersected by four air pipes 16. The outside ends of the 
 pipes are connected to the top of an inner vertical annular 
 casing 3 4. Four oblong apertures 19 are cut below the 
 air pipes, which permit the hot gases from the producer fire 
 to pass into the cover. To the bottom of each pipe is 
 attached a small dish 18. A little water is kept dropping 
 into each dish, and is vaporised by the hot gases in which 
 they are enveloped. The air from the fan is first heated in 
 the coal hopper, and becomes mixed with the steam as it 
 passes out of the dishes, and it drives this forward into the 
 inner casing 3 4, where it is further heated. From the 
 bottom of the casing it enters two pipes 25 which are connected 
 
APPENDIX. 
 
 at opposite sides to a circular passage 23 round the interior 
 of a cast-iron ring grate 21 which carries the firebars 22. 
 Having received additional heat from the grate, the air and 
 vapour now pass out by two segmental slots 24 through the 
 metal on the inside of the ring and on opposite sides just 
 b3low the firebars. These firebars run longitudinally to the 
 air slots, so that the air and steam will pass up into the fire 
 from between the ends of the bars. The steam and hot air 
 now enter the shaft 26, which is encircled by a firebrick 
 lining 27. Having passed through the fire, the gas now 
 
 FIQ. I. 
 
 FIG. 22. ROBSON'S ANTHRACITE GAS PRODUCER PLANT. 
 
 formed passes through the four apertures 19 in the top plate, 
 and into the cover 5 ; from there it passes down between the 
 outside 3 of the inner casing and the outside shell 2. At the 
 bottom of the outer casing is fixed to the producer shell a 
 pipe 28 with two branches 29 30, one of which, 29, is con- 
 nected to a hydraulic box, and the other to a chimney passing 
 through the roof of the producer-house. A throttle valve 
 31 is fitted to the chimney, which must be opened to give 
 ventilation to the fire when the plant is not working, and to 
 maintain the flow of the hot gases down the outer casing 
 which keeps the inner one warm. 
 
APPENDIX. 
 
 195 
 
 (23) Wilson's Gas Producer. Patent No. 26709 of 1902. 
 This producer, shown in Fig. 23, is provided at its lower 
 portion with an air tuyere 2 of inverted V section that extends 
 centrally across it, and is open at the bottom, and with 
 laterally arranged and upwardly extending grates 3 arranged 
 
 FIG. 
 
 .WILSON'S GAS PRODUCER. 
 
 at opposite sides of the tuyere 2, and at the back of which are 
 air supply passages 4, the arrangement being such that air 
 supplied to the central tuyere 2 will be caused to issue from 
 its open bottom and pass up each side thereof into the fuel, 
 whilst air admitted to the passages 4 will be simultaneously 
 
196 APPENDIX. 
 
 delivered into the fuel through each of the two side grates 3, 
 the result being that the air will be distributed amongst the fuel 
 in an advantageous manner, and cause the combustion thereof 
 to take place in a regular and uniform manner. 5 are gas out- 
 lets arranged in the upper portion of the producer, and opening 
 into a flue 7 of inverted V section, which communicates at 
 its ends with an annular flue 8, and is provided with an outlet 
 branch 9, the arrangement being such that the combustible 
 gas produced in the fuel chamber 6 can be drawn off from 
 the central portion thereof in such a manner as to facilitate 
 the uniform combustion of the fuel. The air tuyere 2 is 
 connected at one end with an air supply pipe 10. The lower 
 part of the fuel chamber 6 is provided with a lining 13 through 
 which extend the two air channels 4 which communicate 
 with the inlet end of the air tuyere 2. The lining 13 at parts 
 thereof located at opposite sides of the air tuyere 2 has 
 segmental portions removed therefrom and replaced by the 
 grate bars 3, through which air can pass from the air passages 
 4 at the back of them. The cross flue 7 is supported by an 
 arch 16 of refractory material. At each side of the arch 16, 
 and at parts thereof between its central and end portions, 
 the gas outlet passages 5 are provided. In the wall at the 
 top of the producer is the annular flue 8 that communicates 
 with the cross flues 7, and has a lateral gas outlet branch 9 
 which may be connected to a regenerator through which the 
 hot gas can escape and heat air supplied through another 
 portion thereof to the air supply pipe 10. 
 
 (24) Riche Gas Producer. Patent No. 27533 of 1902. 
 The object of the design shown in Fig. 24 is to insure as far 
 as possible the destruction of the tars and to prevent the 
 clinker from clogging up the column of coke. The chamber B 
 is filled with raw fuel through the inlet A. The base of this 
 chamber forms the furnace, closed by a door J, and provided 
 with an ashpan D : and an overflow pipe Q. At A l is 
 provided a pipe delivering water to the trays B 15 arranged 
 one above the other in the form of steps. E t is the nozzle, 
 for injecting, at the base of the column, the air required for 
 combustion. At the side of the chamber B is arranged a 
 high vertical shaft E filled with coke through the hopper K. 
 At the top of this column is a pipe I for the evacuation of 
 the gases. Between the chamber B and shaft E is arranged 
 a horizontal passage D, at the point F of which air is injected. 
 This passage D compels the columns of raw fuel and coke to 
 
APPENDIX. 
 
 197 
 
 spread at their bases and form inclines closing the ends of 
 the passage or chamber D. The gas producer is started by 
 blowing in an excess of air through the nozzle E! until the 
 column of coke E has become incandescent. Then the air 
 supply through E/ is adjusted for normal working. Water 
 is injected at A l if the fuel does not contain a sufficient amount 
 of moisture of its own. The gaseous mixture produced at 
 the base of the column in the chamber B reaches the passage D 
 
 FIG. 24. RICHE GAS PKODUCER. 
 
 at a high temperature ready for passing through the coke 
 column in the shaft E. The gaseous mixture receives, 
 however, at F additional air, which destroys the greater part 
 of the tars by partial combustion and dissociation. The 
 velocity of the gases in the passage D is reduced on account 
 of its large cross section, so that dust is deposited therein. 
 As the tars are burned in the horizontal passage D before 
 they reach the purifying column of coke, the latter is never 
 
198 
 
 APPENDIX. 
 
 contaminated by either dust or clinker. Its purpose is to 
 transform steam and carbonic acid into combustible gases, 
 while the unburnt, or portion of the tar not dissociated, is 
 transformed into permanent gases. The carbon resulting 
 from the dissociation helps to maintain the purifying column. 
 
 (25) Hislop's Gas Producer. Patent No. 28877 of 1902. 
 The object of this design, shown in Fig. 25, is for the purpose 
 of gasification of slack and also for continuous working. The 
 apparatus comprises a brickwork producer chamber A, having 
 on each side, or centrally as well as on each side, inclined or 
 curved grates B resting on bearing brackets C, through which 
 air and steam are directed into the mass of fuel by blowers H, 
 and a hearth or plate D to support the fuel, and which may 
 be a movable or swivelling plate. When in a horizontal 
 
 FIG. 25. HISLOP'S GAS PRODUCER. 
 
 position it forms a practically solid hearth plate, but when 
 turned up vertically on edge, as shown, it serves to break up 
 and loosen the ash and burnt fuel at the lower part of the 
 producer chamber. The usual water and ashpans E may be 
 provided under the inclined grate bars or gratings B. or a 
 watsr base of any form may be provided, and under each of 
 the grate bars horizontal beams F may extend throughout 
 the length of the producer, and serve not only to support the 
 gratings, but also seal the space under the swivelling base- 
 plate D, so as to exclude ingress of air there when blowers are 
 employed. The producer may be constructed with passages 
 M for the inflow of air or air and steam at the crown of the 
 chamber, and with passages N for the outflow of gases near 
 
APPENDIX. 
 
 199 
 
 the bottom during the period while the coal being gasified is 
 yielding up its volatile matters. The outlet of the gases from 
 the producer may also be reversed by the use of dampers or 
 valves connected to these passages. 
 
 (26) Rowc & Bickerton's Gas Producer. Patent No. 9818 
 of 1903. The object of this design, shown in Fig. 26, is to 
 increase the efficiency and to discharge the producer gas free 
 of tarry matter. The producer comprises a casing B lined 
 with firebrick A. A pips K passes downwards as far as the 
 lower plate M, where it is bolted to another pipe N. The 
 pipe K also carries at its upper end a short cylindrical ex ten- 
 
 FIG. 26. ROWK & BICKERTON'S GUs PRODUCER. 
 
 sion O of greater diameter than the pipe K. Within this 
 extension O, and on the flange H, rests the lower end of a 
 pipe P surrounded with firebrick. This pipe P passes 
 upwards about as far as the throat of the producer. A pipe 
 Q extends downwards from the top plate C, and the lower end 
 of Q is inserted into the upper end of P. A guard S is 
 provided, as shown, to prevent coal from gaining access to 
 the interior of the pipe P. The gases rising from the fuel pass 
 
200 APPENDIX. 
 
 into the annular space X between the guard S and the top of 
 the pipe P, and thus gain access to the interior of the pipe P. 
 This pipe is filled with coke which is kept in an incandescent 
 state by the heat from the partially-burning fuel around the 
 pipe P. The tarry matter is removed by the carbon from 
 the gases, which pass away clean from the lower end of the 
 pipe N by means of the pipe Y. If the gases entering the 
 pipe P contain water vapour or carbon dioxide, the carbon in 
 the retort will act upon these so as to produce hydrogen and 
 carbon monoxide. Water enters the producer by a pipe Z, 
 which discharges the water to a ring 2 arranged below the 
 firebars. The water trickles from this ring down the pipe K, 
 and the heat in this chamber is sufficient to vaporise the 
 amount of water which it is desirable should enter the 
 producer in the form of steam. The discharge pipe Yhas a 
 branch leading to a water seal 5. This acts as a safety valve 
 to prevent any excessive pressure within the gas producer 
 due to an explosion in the discharge pipe Y or its connections. 
 A gas discharge pipe 6 is led from the top of the producer. 
 11 is the air supply pipe. The air is forced into the producer 
 by a fan, blower, or steam jet, and the gas is sucked from the 
 discharge pipe by a fan or pump, or by the engine using the 
 gas during its suction stroke. 
 
 (27) Marechal & Barrierc's Gas Producer. Patent No. 
 12477 of 1903. This producer, shown in Fig. 27, has been 
 designed for the manufacture of a poor gas in large quantities 
 from all sorts of combustibles, and is constructed on the 
 principle of the blast furnace. It consists of three principal 
 parts : (1) The crucible or hearth in which the ashes and 
 clinkers collect ; (2) the boshes in which combustion takes 
 place ; (3) the shaft or stack which contains the charge 
 of combustible and the exit for the gas. The lower part or 
 crucible is composed of a brickwork foundation A A which 
 supports the entire apparatus. On this foundation rests a 
 plate B which serves as a support for the boshes. The chamber 
 below the plate contains a U-shaped boiler D, which furnishes 
 the steam necessary for the production of the gas. This 
 steam is injected at the base of the column of the incandescent 
 combustible, or fuel, through a series of small nozzles E. 
 The boshes G are made of refractory bricks, in which is formed 
 an annular chamber H, from which pass superposed rows of 
 tuyeres I, which deliver heated air from a regenerator to 
 the incandescent combustible. These tuyeres extend across 
 
APPENDIX. 
 
 201 
 
 to the outer wall, and are closed by small clay plugs F ; this 
 arrangement has for its object to allow the combustible to 
 be stoked from the sides. On the boshes is arranged the 
 double truncated shaft K. This shaft has a double wall 
 forming a water-jacket ; its inner wall M is furnished with a 
 series of ribs N, which serve to direct the gases towards the 
 centre. The shaft is closed by a cover having a peripheral 
 
 FIG. 27. MARCHAL & BARRIEKE'S GAS PRODUCER. 
 
 flange and a number of openings suitable for charging devices 
 P. At the centre of the cover is fixed a truncated bell Q 
 projecting into the interior of the stack, and through which 
 bell the gas is exhausted. Above this bell is an opening 
 through the cover, which is kept closed by a lid R of glass 
 or mica with waterseal, so that the working of the operations 
 
202 APPENDIX. 
 
 may be observed. The tank formed by the cover communi- 
 cate? through a pipe S with the lower part of the water- 
 jacket of the shaft K, and the upper part of this latter com- 
 municates in its turn through a pipe T with the lower part 
 of the boiler D in the crucible. The gases leave the producer 
 through the pipe U. 
 
 (28) Gas Producers. Patent No. 12506 of 1903. This 
 in vention,by La Societe Francaise de Constructions Mecaniques, 
 Paris, has for its object to provide a producer for use in the 
 manufacture of poor gas, for heating or motive power purposes. 
 The producer is provided with means such that the tempera- 
 ture in any part of the producer is prevented from 
 exceeding 1,200 or 1,300 C., so that the fusion of the residue 
 resulting in the production of clinker is avoided. This result 
 is obtained by supplying to the lower part of the combustion 
 chamber air diluted with gas mixed with the air in such propor- 
 tion that (its temperature being taken into account) the 
 gaseous products and solid residues of the combustion do 
 not attain such temperature as would cause the production of 
 clinker. The gas which is used for diluting the air in accord- 
 ance with this invention is that produced in the gas producer, 
 the proportion of such gas being greatly in excess of that 
 which would form with the air with which it is mix d an 
 entirely combustible mixture. The accompanying vertical 
 sections show a few arrangements of the producer. In the 
 arrangement shown in Fig. 28 the shaft is made narrower at 
 its lower part A than above, this narrower part being followed 
 by a gradual enlargement B. The mixture of air and gas is 
 kept in motion by the action of a fan C drawing gases from 
 the upper part of the producer and forcing them into a 
 passage or passages, such as at D, which opens, or open, into 
 a space immediately below the narrow part A of the producer 
 shaft. Fig. 28A shows another arrangement of the lower 
 part of the gas producer. The two arched spaces E. 
 which cause the fuel and ash or residue to spread and form 
 inclines, are diametrically opposite each other and above 
 the openings for the introduction of the mixture of air and 
 gas which enter by the passages D. In the arrangement 
 shown in Fig. 28s the producer receives, from an external 
 apparatus, the gaseous mixture required to maintain the 
 combustion, and is provided with only one lower arched 
 space G, leaving on each side thereof a passage for the descent 
 of the fuel and ash or residue, the circulation of the mixture 
 
APPENDIX. 
 
 203 
 
 of air and gas being effected by a compressed-air injector 
 or injectors, F. 
 
 (29) Duffs Gas Producer. Patent No. 16164 of 1903. 
 This invention relates to a method of distributing the air, 
 or air and steam, to the fuel in gas producers. In the centre 
 
204 
 
 APPENDIX. 
 
 of the trough B (Fig. 29) is built a casing C upon which is 
 superposed a ring of vertical gratings D. On the top of this 
 ring^of gratings I) there is placed a conical louvre ring F, and 
 on the top of the ring F a cover G is so secured that an air 
 space J is left between the ring F and the cover G, and the 
 whole forms a louvred cone having a closed top. The air, 
 
 FIG. 29. DUFF'S IMPROVEMENTS IN GAS PRODUCERS. 
 
 or air and steam, for combustion or gasification of the fuel is 
 supplied to the casing C through a duct K, communicating 
 outside the producer shell A with a blower pipe L. The air 
 passes from the casing C into the producer, both through he 
 gratings D and the air space J. The duct K is provided with 
 a door M, through which a rake can be inserted to clean out 
 any residues which may become deposited in the casing C. 
 
APPENDIX. 
 
 205 
 
 The streams of air, or air and steam, issuing from the two 
 blowers at the same time act consecutively upon the fuel as 
 the latter moves downwards, the upper conical blower 
 delivering air to light up the fuel to incandescence, while the 
 lower grating causes the air to act upon the fuel with a fine 
 distribution. 
 
 FIG. 30. FEEDING MECHANISM AND AIR SUPPLY APPARATUS 
 FOB PRODUCERS. 
 
 (30) George's Gas Producer. Patent No. 16263 of -j 1903. 
 This invention relates to the construction of fuel-feeding 
 mechanism and air supply apparatus for gas producers. The 
 
206 APPENDIX. 
 
 feeding mechanism is shown in Fig. 30, and has for its object 
 to provide means for the uniform and even distribution of the 
 coal to the heating chamber. It comprises a chamber D 
 provided with an opening F, through which coal is delivered 
 to a rotating coal distributor G. The chamber D is 
 provided with a flange H extending over and covering the 
 upper end of the coal distributor G. The lower end of the 
 coal distributor is provided with a smaller opening I eccentric 
 to its axis of rotation, whereby the side walls of the coal 
 distributor are given a varying inclination to a vertical plane. 
 The coal distributor G is suspended by means of a central 
 hub J which is attached to a spindle K capable of turning in 
 a bearing L supported concentrically in the chamber D. 
 Projecting from the hub J is a disc M slightly inclined from 
 a horizontal plane, and larger than the delivery opening F, 
 with an annular space between the edge of the disc M and the 
 inner walls of the coal distributor. The coal distributor is 
 provided with ratchet teeth N, which are engaged by an 
 actuating pawl O carried on an arm P of an oscillating shaft Q. 
 The lower end of the coal distributor is provided with a dish- 
 shaped flange R extending over and covering the opening C 
 in the top of the heating chamber, and adapted to contain 
 water by which the mouth of the coal distributor is cooled. 
 The joints between the coal distributor and the top of the 
 heating chamber and between the coal distributor and the coal 
 magazine are water sealed to prevent the passage of gas. 
 The proper distribution of air to the bottom of the heating 
 chamber is accomplished by the apparatus shown in the 
 lower view, Fig. 30, and consists of the conical hoods V and W, 
 one placed above the other, with the upper hood V supplied 
 with air through an air passage X, while the lower hood W is 
 supplied with air through an independent air passage Y, with 
 the passages X and Y controlled by a common sliding damper 
 Z, by which the air passage Y may be closed and the air 
 passage X opened, or vice versa, thereby regulating the relative 
 amount of air which passes upward through the bed of coal U 
 over the edges of the two hoods V and W. 
 
 (31) Hovinc & Breuille's Gas Producer. Patent No. 25763 
 of 1903. This producer is shown in Fig. 31. It com- 
 prises two chambers, the gas generator 1 and the regulating 
 chamber 2, separated by a partition 3, and in open communi- 
 cation with each other through opening 4. The sides 5 of the 
 gas generator are inclined, and at a certain distance from the 
 
APPENDIX. 
 
 207 
 
 bottom of the ashpit a grate 6 is fitted. At the top of the 
 apparatus are arranged charging devices 7 and apertures 8 for 
 poking the fuel. The chamber 2 is provided with a grate 9 
 to support the pieces of non-flaming fuel filling the chamber 2. 
 A tight-closing plug 10 enables the charging to be effected 
 
 Sectional Plan. Section on line ZZ of Fig. 1. 
 
 FIG. 31. HOVINE & BREUILLE'S GAS PRODUCER. 
 
 whenever necessary. Below the grate 9 are arranged separate 
 heating apparatus. One of them, 11, serves for superheating 
 steam admitted through the pipe 12 and passing under the 
 grate 6 through a pipe 13 ; and the other, 14, serves to heat 
 the atmospheric air blown in by the fan 15. At the bottom 
 of the regulating chamber, and below the heating apparatus, 
 
208 APPENDIX. 
 
 is the end of a pipe 18 connected to a fan which continuously 
 exhausts the gas generated and discharges it through a pipe 
 into the holder. Steam required for the generation of gas 
 is supplied during normal working by the exhaust from the 
 engine, through the pipe 12, which discharges it into the heater 
 11. To provide the required quantity of steam at starting a 
 separate boiler is provided, the steam being admitted through 
 the pipe 29 into the heater 11. 
 
 In cases where fuel very rich in volatile substances is 
 used the regulating chamber 2 is provided with a supple- 
 mentary chamber 30 arranged in the upper portion of the 
 gas generator near the inlet for the fuel. This chamber 30, 
 where the fuel is subjected to a beginning of distillation, 
 enables gaseous hydrocarbons, which are disengaged by it, to 
 be collected ; they are exhausted by means of steam injectors 
 34, and discharged through orifices 33 above the grate 6 of the 
 gas generator among the incandescent fuel, so that they are 
 decomposed, heat and fixed gases being generated. The 
 conduits 35 withdraw the preliminary products of 
 distillation. 
 
 (32) Dunlop's Self-contained Self-regulating Gas Plant. 
 This plant, shown in Fig. 32, is intended to produce from 
 bituminous slack a gas suitable for use in gas engines without 
 thd necessity of any attention further than that of filling the 
 generator completely with fuel and turning on a supply of 
 water. It consists of a metal shell with an inner shell lined 
 with firebrick. At the* lower end is a rocking grate with a 
 poking finger. The shells are so arranged that free com- 
 munication is established at all times between the top and 
 bottom of the generator. Placed centrally in the generator 
 is a water- jacketed collecting pipe, through which the gases 
 produced are drawn off to be cooled and washed. The fuel 
 is supplied by two hoppers at the top, and the water supply 
 to the collecting pipe jacket is regulated by a cock, and sealed 
 by a siphon pipe, as shown. The collecting pipe jacket is in 
 free communication with the top of the generator, the upper 
 end of the collecting pipe being closed by a lid, through which 
 the condition of the fire may be observed, or through which 
 the fire may be started by a piece of cotton waste soaked in 
 petroleum. This lid is kept off during such time as the 
 generator is being got into working order. From the collecting 
 pipe the gases pass to a tubular heat interchanger, shown at 
 the side of the generator, the gases passing downwards, inside 
 
APPENDIX. 
 
 209 
 
 the tubes, which are in two lengths telescoping each other. 
 The water overflowing from the collecting pipe jacket passes 
 by a siphon seal to the top of the heat interchanger, and, 
 flowing over the upper ends of the tubes, descends in a film 
 inside the tubes along with the gases. At the same time a 
 
 FIG. 32. DUNLOP'S SELF-CONTAINED SELF-REGULATING GAS PLANT. 
 
 regulated quantity of steam is mixed with the gases as they 
 leave the collecting pipe, the pinching screw and locknut 
 shown at the top of the collecting pipe hood forming a readily 
 adjustable means of insuring this result. The film of water 
 
210 APPENDIX. 
 
 descending the tubes of the heat interchanger is trapped 
 between the tubes at the bottom, and so maintains a constant 
 level of water in the heat interchanger, and at the same time 
 effectively seals the tubes, so that they are free to expand or 
 contract without escape of gas. Around the outside of the 
 tubes passes the air supply to the gas generator, the air 
 entering the adjustable opening close to the surface of the 
 water, and passing into the lining of the generator near the top. 
 The surplus water from the bottom of the heat interchanger 
 passes away through a siphon seal, and a fresh supply of cold 
 water enters along with the gases into a centrifugal cooler and 
 washer. This cooler and washer consists of an exhaust fan 
 driven by the engine at a moderate speed sufficient to relieve 
 the engine of the work of drawing the gases through the 
 generator, &c. The construction is specially designed for the 
 purpose of condensing the steam mixed with the gases, and 
 for removing any tarry vapours or other condensible hydro- 
 carbons that may have passed over along with the gases. For 
 these purposes the periphery of the fan is surrounded by a 
 U-shaped ring, which maintains a water seal around the 
 periphery, and through which all the gases must pass on their 
 way to the engine. The water overflowing this seal is spread 
 out in a sheet around the ring, so that after passing the seal 
 the gases must again pass through water before leaving the 
 fan chamber by the branch at the top. The fan chamber 
 provides sufficient storage for supplying each cycle of the 
 engine's operations. The water passing the fan is drained 
 from the bottom of the chamber by a siphon seal. 
 
APPENDIX III. 
 
 BIBLIOGRAPHY. 
 
 THE descriptions of the various forms of gas producers are 
 scattered through the various engineering journals and the 
 records of the Patent Office, and a list of such, whilst it would 
 be very long, would be of little interest or use ; and no reference 
 is made therefore to papers which are merely a description of 
 some new form of gas producer. 
 
 The papers mentioned below deal with the principles and 
 problems of gas production and the use of gaseous fuel, and most 
 of them are well worth study. In some cases, where the author 
 has not had access to the papers themselves, reference is given 
 to a published abstract, and only papers printed in English, 
 and which are likely to be fairly accurate, are given. Abstracts 
 of most of the foreign papers appear in the Journal of the Iron 
 and Steel Institute and in the Journal of the Society of Chemical 
 Industry. 
 
 The papers are arranged, as far as possible, chronologically, 
 so that they will give an idea of the development of the use of 
 fuel gas. 
 
 No attempt has been made to prepare a complete biblio- 
 graphy of the subject, but only to give references to such papers 
 as are likely to be of use. Those of special importance are 
 marked with an asterisk. 
 
 Books dealing with the subject of Fuel, and incidentally with 
 Gaseous Fuel : 
 
 METALLURGY. By John Percy, M.D., F.R.S. Vol. I. Intro- 
 ductory ; refractory materials and fuel. London : Murray. 
 2nd edition, 1875. 
 At the time this volume was published gaseous fuel was only 
 
 just coming into use, so that but little space is given to it. 
 
 Ekmans and Siemens producers and furnaces are described. 
 
 GASEOUS FUEL : INCLUDING WATER GAS. By B. H. Thwaite, 
 F.C.S. London : Whittaker & Co., 1888. 
 
 Contains information relating to the production and appli- 
 cation of gaseous fuel. 
 
 FUEL AND ITS APPLICATIONS. By E. J. Mills, D.Sc., and F. J. 
 
 Rowan, C.E. London : Churchill, 1889. 
 Contains all the information available up to the date of 
 publication. 
 FUEL AND REFRACTORY MATERIALS. By A. Humboldt Sexton, 
 
 F.I.C., F.C.S. London : Blackie & Sons, 1897. 
 A handy book dealing with the whole subject. Most modern 
 books on the metallurgy of steel and on gas engines contain 
 sections on gas production. 
 
212 APPENDIX. 
 
 ABBREVIATIONS USED. 
 
 J. = Journal of the Iron and Steel Institute. 
 
 W. = Journal of the West of Scotland Iron and Steel Institute. 
 C.E. = Minutes of Proceedings of the Institution of Civil Engineers. 
 M.E. = Minutes of Proceedings of the Institution of Mechanical 
 Engineers. 
 
 A. = American Institution of Mining Engineers. 
 O.I. = Journal of the Society of Chemical Industry. 
 
 Papers dealing with the subject of Fuel, and incidentally with 
 
 Gaseous Fuel : 
 A NEW CONSTRUCTION OF FURNACE SPECIALLY APPLICABLE 
 
 WHERE INTENSE HEAT is REQUIRED. By W. Siemens. 
 
 M.E., 1857, 103. Collected Works, Vol. I., 62. 
 ON A REGENERATIVE FURNACE APPLIED TO GLASSHOUSES, 
 
 PUDDLING, HEATING, &c. By W. Siemens. M.E., 1862, 
 
 21 and 40. Collected Works, Vol. I., p. 81. 
 ON A STEAM JET FOR EXHAUSTING AIR, &c., AND SOME RESULTS 
 
 OF ITS APPLICATION. By. W. Siemens. M.E , 1872, p. 97. 
 
 Collected Works, Vol. I., p. 141. 
 ON THE USE OF COAL GAS AS A FUEL. C.I., 1881, p. 39. 
 
 Collected Works, Vol. I., p. 177. 
 ON THE REGENERATIVE GAS FURNACE AS APPLIED TO THE 
 
 MANUFACTURE OF CAST STEEL. By W. Siemens. Journal 
 
 of the Chemical Society, 1868, p. 279. Collected Works, 
 
 Vol. I., p. 209. 
 
 'GAS PRODUCERS. By F. J. Rowan. C.E., LXXXIV., p. 3. 
 ON THE MOST RECENT RESULTS OBTAINED IN THE APPLICATION 
 
 AND UTILISATION OF GASEOUS FUEL. By W. S. Suther- 
 land. J., 1884, Vol. I., p. 72. 
 ON A MODIFIED FORM OF THE SIEMENS PRODUCER. By John 
 
 Head. J., 1885, Vol. I., p. 126. 
 WATER GAS FOR METALLURGICAL PURPOSES. By A. Wilson. 
 
 J., 1888, Vol. I., p. 86. 
 GASEOUS FUEL. By Sir Lowthian Bell. J., 1889, Vol. II., 
 
 p. 139. 
 A NEW FORM OF SIEMENS FURNACE. By J. Head and M. P. 
 
 Pouff. J., 1889, Vol. II., p. 256. 
 WATER GAS IN THE UNITED STATES. By A. C. Humphreys. 
 
 J. (abs.), 1889, Vol. II., p. 360. 
 MONO GAS. (Address of President at Annual Meeting of the 
 
 Soc.C.I.) By L. Mond. C.I., 1889 (VIII.), p. 503. 
 FUEL GAS. By G. W. Goetz. A., Vol. XVIII. ; J. (abs.), 1890, 
 
 Vol. I., p. 243. 
 
APPENDIX. 213 
 
 FUEL GAS AND SOME OF ITS APPLICATIONS. By Burdett Loomis. 
 
 J., 1890, Vol. II., p. 275. 
 PHYSICAL AND CHEMICAL EQUATIONS OF THE OPEN-HEARTH 
 
 PROCESS. By H. H. Campbell A., XIX. (1889), p. 128. 
 GAS FURNACES. By B. Dawson. M.E., 1891, p. 47. 
 GAS PRODUCERS. By R. Booth. Society of Civil and 
 
 Mechanical Engineers, 1891. J. (abs.), 1892, Vol. I., 
 
 p. 342. 
 FUEL GAS. By A. Kitson. Journal of the Franklin Institute. 
 
 Vol. CXXXIL, p. 424. J. (abs.), 1892, Vol. II., p. 387. 
 GASEOUS FUEL. By G. Ritchie. W., Vol. I., p. 117. 
 RECOVERY OF BY-PRODUCTS FROM PRODUCER GAS. By A. 
 
 Gillespie. W. 
 MOND PRODUCER GAS APPLIED TO THE MANUFACTURE OF STEEL. 
 
 By J. H. Darby. J., 1896, Vol. I., p. 144. 
 THE EFFICIENCIES OF GAS PRODUCERS. By C. J. Jenkin, B.A., 
 
 C.E. (1895-96), CXXIIL, p. 328. 
 THE MOND GAS PRODUCER PLANT AND ITS APPLICATION. By 
 
 H. A. Humphrey. C.E., CXXIX. (1897), p. 190. 
 THE WEARDALE FURNACE. By H. W. Hollis. J., 1897, Vol. I., 
 
 p. 56. 
 COMPARISON OF GAS PRODUCERS. By F. L. Slocum. C.I., 
 
 Vol. XVI. (1897), p. 420. 
 ON THE USE OF BLAST-FURNACE GAS FOR A MOTIVE POWER. 
 
 By A. Greiner. J., 1898-1, p. 21. 
 
 FUEL FOR. GAS PRODUCERS. By C. W. Bildt. A., 1898; J. 
 
 (abs.), 1898, Vol. L, p. 401. 
 THE USE OF BLAST-FURNACE AND COKE-OVEN GASES. By E. 
 
 Disdier. J., 1899, Vol. L, p. 143. 
 
 THE MANUFACTURE AND APPLICATION OF WATER GAS. C. 
 Dellwik. J., 1900, Vol. L, p. 119. 
 
 POWER GAS AND LARGE GAS ENGINES FOR CENTRAL STATIONS. 
 By H. A. Humphrey. M.E., 1901, p. 41. 
 
 WATER GAS. President's Address to the Eighteenth Annual 
 Meeting of the Society of Chemical Industry, 1899. C.I., 
 Vol. XVIII, p. 642. 
 
 GAS PRODUCERS. By A. Wilson. W, Vol. VIII. (1901), p. 135. 
 
 DUFF PRODUCERS AND AMMONIA RECOVERY. By F. J. Rowan. 
 Iron and Coal Trades' Review, Vol. LXII, p. 68. 
 
 PRODUCER GAS AND ITS APPLICATIONS. By F. J. Rowan. 
 A series of articles in the Iron and Coal Trades' Review, 
 1901, reprinted in pamphlet form. 
 
214 APPENDIX. 
 
 WATER GAS. By G. Lunge. Mineral Industry, Vol. IX., p. 148. 
 
 J. (abs.), 1901, Vol. II., p. 395. 
 GASES FROM WOOD FOR THE MANUFACTURE OF STEEL. By J. 
 
 Douglas. J., 1902, Vol. I., p. 287. 
 GAS PRODUCERS. By J. E. Dowson. Journal, Franklin Institute 
 
 Vol. CLIL, p. 275. J. (abs.), 1902, Vol. I., p. 484. 
 PRESIDENTIAL ADDRESS TO THE INSTITUTE OF ENGINEERS AND 
 
 SHIPBUILDERS, SCOTLAND. By W. Foulis. 1901. 
 USE OF PRODUCER GAS. By F. J. Rowan. Institution of 
 
 Engineers and Shipbuilders. 1902. 
 
INDEX. 
 
 PAGE 
 
 Acetylene 30 
 
 Acetylene, Calorific Power of... 20 
 Acetylene, Heat Formation of 17 
 
 Acetylene, Properties of 5 
 
 Adjustable Jet 52 
 
 Advantages of Producer Gas ... 128 
 Air and Steam for Gas Pro- 
 ducers, Superheating 115 
 
 Air and Steam, Proportions of, 
 
 Required for Producers 57 
 
 Air and Steam, Quantity of, 
 
 Required for Producers 57 
 
 Air, Composition of 6, 33 
 
 Air Required for Combustion... 12 
 Air Supply to Gas Producers... 112 
 Air Supply to Producer from 
 
 below Bars 112 
 
 Air Supply to Producers, 
 
 Central 113 
 
 Air Supply to Producers, 
 
 Circumferential 114 
 
 Atkinson (Crossley and) Pro- 
 ducer 176 
 
 Ammonia Recovery in Mond 
 
 Process 91 
 
 Ammonia, Recovery of, from 
 
 Producer Gas 125 
 
 Annular Jet 51 
 
 Argand Jet 53 
 
 Ashes, Loss of Heat in, from 
 
 Producer 44, 117 
 
 Ash, Removal of, from Pro- 
 ducers 119 
 
 Automatic Producers 78 
 
 Bar-bottom Producers 62 
 
 Barriere (Marechal and) Pro- 
 ducer 200 
 
 Batho Furnace 139 
 
 Beanes and Werner Producer 190 
 Bickerton (Rowe and) Producer 199 
 
 Bischof Producer 34 
 
 Blast-furnace Gas 82 
 
 Blast Furnace, The, as a Pro- 
 ducer 82 
 
 Blower. (See Jet.) 
 
 Blower, Power of 56 
 
 Blower, Principle of 50 
 
 Blower, Quantity Steam re- 
 quired for 56 
 
 Blower, Siemens 48 
 
 Blower, Steam Jet 48 
 
 Blower, Tube 55 
 
 PAGE 
 
 Boiler Firing, Advantages of 
 
 Gas for 134 
 
 Boiler Firing, Combustion 
 
 Chamber for 129 
 
 Boiler Firing, Tate System ... 132 
 Boiler Firing, Use of Mond Gas 
 
 for 133 
 
 Boiler Firing, Use of Water Gas 
 
 for 133 
 
 Boilers, Result of Gas Firing 133 
 
 Bowman Producer 179 
 
 Boyd Producer 115 
 
 Boyle's Law 8 
 
 Breuille (Hovineand) Producer 206 
 
 Brick Kiln, Gas-fired 145 
 
 British Thermal Unit 16 
 
 B.Th.U 16 
 
 Burner for Producer Gas .. . 129 
 
 Calcination of Ores by Gas ... 147 
 
 Calorie 16 
 
 Calorific Intensity 21 
 
 Calorific Intensity of Carbon ... 21 
 Calorific Intensity of Carbon- 
 monoxide 22 
 
 Calorific Intensity of Hydrogen 22 
 Calorific Intensity of Marsh 
 
 Gas 23 
 
 Calorific Power 16, 23, 27 
 
 Calorific Power of Acetylene... 20 
 
 Calorific Power of Carbon 17 
 
 Calorific Power of Carbon- 
 monoxide 17 
 
 Calorific Power of Coal Gas ... 27 
 
 Calorific Power of Ethylene ... 20 
 Calorific Power of Gaseous 
 
 Fuels, Calculating 19 
 
 Calorific Power of Hydrogen ... 18 
 
 Calorific Power of Methane ... 19 
 Calorific Power of Producer 
 
 Gas, Simple 34 
 
 Calorific Power of Producer 
 
 Gas, Steam Enriched 37 
 
 Calorific Power of Producer 
 
 Gas, Coal Enriched 39 
 
 Calorific Power of Solid Fuels, 
 
 Calculation of 18 
 
 Calorific Power of Water Gas... 109 
 
 Carbon, Calorific Intensity of.. 21 
 
 Carbon, Calorific Power of ... 17 
 Carbon-dioxide, Apparatus for 
 Determining in Producer Gas 151 
 
11. 
 
 INDEX. 
 
 PAGE 
 Carbon-dioxide as Measure of 
 
 Completeness of Combustion 154 
 Carbon-dioxide as Measure of 
 
 Quality of Gas 151 
 
 Carbon-dioxide in Flue Gases... 154 
 Carbon-dioxide in Producer 
 
 Gas 40, 117, 151 
 
 Carbon-dioxide in Producer 
 
 Gas, Sources of 41 
 
 Carbon-dioxide, Properties of 5 
 Carbon, Heat of Formation of 
 
 Hydrocarbons 17 
 
 Carbon-monoxide, Calorific In- 
 tensity of . ; .... 22 
 
 Carbon-monoxide, Calorific 
 
 Power of 17 
 
 Carbon-monoxide, Properties of 3 
 
 Centigrade Unit of Heat 15 
 
 Charging Producers 118 
 
 Charles Law 9 
 
 Chimney-draught Producers 46, 58 
 
 Closed-hearth Producers 61 
 
 Closed-hearth Producers, Clas- 
 sification of 62 
 
 Closed-hearth Producer, Sie- 
 mens 62 
 
 Coals, Coking, Use of, in Gas 
 
 Producers 120 
 
 Coal-enriched Producer Gas ... 38 
 
 Coal Gas 26 
 
 Coal Gas as a Fuel 27 
 
 Coal Gas, Calorific Power of ... 27 
 
 Coal Gas, Composition of 26 
 
 Coking Coals, Use of, in Gas 
 
 Producers 120 
 
 Combustible Gases in Fuel Gas 2 
 Combustion, Air Required for 
 
 12, 27, 30 
 Combustion, Heat of. (See 
 
 Calorific Power.) 
 Combustion, Oxygen Required 
 
 for 13, 27, 30 
 
 Combustion, Products of 13 
 
 Combustion, Temperature of... 23 
 Composition of Gases by 
 
 Weight, Calculation of 11 
 
 Condensing Plant, Mond 89 
 
 Contact, Heating by "24 
 
 Control of Gas Production ... 150 
 
 Cooling Tube, Overhead 46 
 
 Cost of Producer Gas 127 
 
 Craig Apparatus for Deter- 
 mining Carbon-dioxide in 
 
 Producer Gas 151 
 
 Crossley and Atkinson Producer 176 
 Crossley and Rigby Producer... 2 
 
 Daniel Producer 
 Davis-Colby Kiln 
 
 181 
 
 146 
 
 PAGE 
 
 Dawson Producer 73 
 
 Dellwik-Fleischer Producer ... 102 
 Dellwik-Fleischer Water-gas 
 
 Plant 102 
 
 Diluents in Fuel Gas 2 
 
 DoAvn-draught Producers 80 
 
 Dowson Producer 63, 192 
 
 Dowson Producer, New Form 64 
 Duff Plant for making Mond 
 
 Gas 92 
 
 Duff Producer 73, 172, 203 
 
 Duff-Whitfield Producer 125 
 
 Dunlop Producer 208 
 
 Dunnachie Gas Kiln 145 
 
 Dymond Producer 162 
 
 Efficiency, Hot-gas 44 
 
 Efficiency of Gas Producers ... 42 
 
 Ethylene, Calorific Power of... 20 
 
 Ethylene, Heat of Formation of 17 
 
 Ethylene, Properties of 4 
 
 Evaporative Power 16 
 
 Expansion of Gases by Heat ... 9 
 
 Fielding Producer 182 
 
 Figure of Merit 45 
 
 Flue Gases, Carbon-dioxide in 154 
 Forced-draught Producers ..." 48 
 
 Fraser-Talbot Producer 120 
 
 Fuel Gas, Gases in 2 
 
 Furnace for Gas Firing with 
 Regenerators. (See Regene- 
 rative Furnaces.) 
 Furnaces for Gas Firing With- 
 out Regenerators 135 
 
 Gas, Advantages of, for Boiler 
 
 Firing 134 
 
 Gas, Blast-Furnace 82 
 
 Gas Engines 148 
 
 Gas Firing for Boilers, Results 133 
 
 Gas for Calcining Ores 146 
 
 Gas for Firing Bricks, &c 146 
 
 Gas for Gas Engines 148 
 
 Gas for Gas Engines, Dowson 148 
 Gas for Gas Engines, Mond ... 149 
 Gas for Gas Engines, Water ... 149 
 Gas for Regenerative Furnace 140 
 
 Gas Kiln, Davis-Colby 147 
 
 Gas Kiln, Dunnachie 146 
 
 Gas, Mond 86 
 
 Gas Producers. (See Producer.) 
 Gas Production, Control of ... 150 
 
 Gas, Water 95 
 
 Gases, Expansion of by Heat... 
 Gases, Sensible Heat of 45 
 
INDEX. 
 
 PAGE 
 
 Gases, Utilisation of Sensible 
 
 Heat of 46 
 
 Gases, Variation of Volume 
 
 by Pressure 7; 
 
 Gases, Variation of Volume 
 
 with Changes of Temperature 9 
 Gaseous Fuels, Calculation of 
 
 Calorific Power of 19 
 
 Gasification, Rate of in Pro- 
 ducers 114 
 
 Genty Producer 168 
 
 George Producer 205 
 
 Gorman Furnace 143 
 
 Granger's Jet 54 
 
 Hanging Grate 75 
 
 Heat Carried Away by Pro- 
 ducts of Combustion 24 
 
 Heat Carried off by Gases 43 
 
 Heat Evolved in Producer... 
 
 34, 38, 41 
 Heat, Loss of, by Radiation 43, 117 
 
 Heat, Loss of in Ashes 44, 117 
 
 Heat, Loss of, in Gas Pro- 
 ducers 43, 115 
 
 Heat of Combustion. (See 
 
 Calorific Power.) 
 Heat of Formation of Hydro- 
 carbons 17 
 
 Heating by Contact and 
 
 Radiation 24 
 
 Heating Power, Absolute. (See 
 
 Calorific Power.) 
 Heating Power, Pyrometric. 
 (See Calorific Intensity.) 
 
 Herrick Producer 174 
 
 Hill (Schill and) Producer ... 185 
 
 Hislop Producer 198 
 
 Hot Gas Efficiency 44 
 
 Hot Gas, Use of 44 
 
 Hovine and Breuille Producer 206 
 
 Humfrey Producer 160 
 
 Hydrocarbons, Heat of Forma- 
 tion of 17 
 
 Hydrogen, Calorific Intensity of 22 
 Hydrogen, Calorific Power of.. 18 
 Hydrogen, Properties of 2 
 
 Jet, Adjustable 52 
 
 Jet, Annular 51 
 
 Jet, Argand 53 
 
 Jet, Granger's 54 
 
 Jet, Korting's 54 
 
 Jet, Simple 51 
 
 Jet, Thwaite Adjustable 53 
 
 Kiln, Davis-Colby 147 
 
 Kiln, Dunnachie 145 
 
 PAGE 
 
 Kiln, Gas 145, 147 
 
 Korting's Jet 54 
 
 Korting's Producer 81 
 
 Leeds Forge Water-gas Plant 96 
 Loomis-Pettibone Producer ... 100 
 Loomis-Pettibone Water-gas 
 
 Plant 100 
 
 Loomis Water-gas Plant 99 
 
 Lowe Water-gas Plant 96 
 
 Lowe Water-gas Producer 99 
 
 Luminous Flame, Efficiency of 24 
 
 Marechal and Barriere Pro- 
 ducer 200 
 
 Marsh Gas, Calorific Intensity 23 
 
 Marsh Gas, Calorific Power of 20 
 
 Marsh Gas, Heat of Formation 17 
 
 Marsh Gas, Properties of 4 
 
 Merit, Figure of 45 
 
 Methane. (See Marsh Gas.) 
 Moisture. (See Water.) 
 
 Mond Condensing Plant 89 
 
 Mond Gas 86 
 
 Mond Gas, Duff Plant for ... 92 
 Mond Gas for Boiler Firing... 133 
 Mond Gas, Recovery of Ammo- 
 nia in Preparation of 91 
 
 Mond Plant, Cost of Working 91 
 
 Mond Producer 87 
 
 Natural Gas 26 
 
 Nitrogen, Properties of 5 
 
 Oil Gas 29 
 
 Overhead Cooling Tube 46 
 
 Oxygen, Amount Required for 
 
 Combustion 13, 27, 30 
 
 Oxygen, Properties of 5 
 
 Pintsch Producer 165 
 
 Power of Blowers 56 
 
 Pressure, Changes of, Influence 
 
 on Volume of Gas 8 
 
 Producer, Air and Steam 
 
 Required for 57 
 
 Producer, Air Supply to 112 
 
 Producer, Air Supply from 
 
 Below Bars 112 
 
 Producer, Automatic 78 
 
 Producer, Bar-bottom 62 
 
 Producer, Beanes and Werner 190 
 
 Producer, Bischof 34 
 
 Producer, Bowman 179 
 
 Producer, Boyd 115 
 
 Producer, Central Air Supply 
 
 to 113 
 
 Producers, Charging 118 
 
IV. 
 
 INDEX. 
 
 PAGE 
 
 Producers, Chimney-draught 
 
 46, 58 
 Producers, Circumferential Air 
 
 Supply to 114 
 
 Producers, Closed-hearth 61 
 
 Producers, Closed-hearth, Classi- 
 fication of 62 
 
 Producers, Conditions to be 
 
 Fulfilled Ill 
 
 Producer, Conversion of Sie- 
 mens Open to Solid-bottom 69 
 
 Producer, Cost of 127 
 
 Producer, Crossley and Atkin- 
 son 176 
 
 Producer, Crossley and Rigby 
 
 187, 188 
 
 Producer, Daniel 181 
 
 Producer, Dawson 73 
 
 Producer, Dellwik-Fleischer ... 102 
 
 Producer, Down-draught 80 
 
 Producer, Dowson 63, 192 
 
 Producer, Dowson, New Form 64 
 
 Producer, Duff 73, 172, 203 
 
 Producer, Duff-Whitfield 125 
 
 Producer, Dunlop 208 
 
 Producer, Dymond 162 
 
 Producer, Efficiency of 42 
 
 Producer, Evolution of Heat in 
 
 34, 38, 41 
 
 Producer, Fielding 182 
 
 Producer for Use with Wood... 65 
 Producer, Fraser-Talbot ...... 120 
 
 Producer Gas 32 
 
 Producer Gas, Advantages of 128 
 
 Producer Gas, Burner for 129 
 
 Producer Gas, Calculation of 
 
 Composition of 37 
 
 Producer Gas, Carbon-dioxide 
 
 in 40, 117 
 
 Producer Gas, Coal-enriched... 38 
 
 Producer Gas, Cost of 127 
 
 Producer Gas, Economy due to 
 
 Use of Steam in 38 
 
 Producer Gas, Effects of 
 
 Excess of Steam 41 
 
 Producer Gas, Effect of Re- 
 moving Tar from 121 
 
 Producer Gas for Firing Boilers 128 
 Producer Gas from Refuse 
 
 Destroyers 150 
 
 Producer Gas, Loss of Heat in 
 
 Production of 34, 38 41 
 
 Producer Gas, Quality of 118 
 
 Producer Gas, Recovery of 
 
 Ammonia from 125 
 
 Producer Gas, Removal of Tar 
 
 from 120 
 
 Producer Gas, Simple 32 
 
 Producer Gas, Simple, Calori- 
 fic Power of 34 
 
 Producer Gas, Steam-enriched 35 
 
 PAGE 
 
 Producer Gas, Steam in 117 
 
 Producer Gas, Use of Steam in 
 
 Making 35 
 
 Producer Gas, Using 128 
 
 Producer Gas, Washing to 
 
 Remove Tar 125 
 
 Producer, Genty 168 
 
 Producer, George 205 
 
 Producer, Herrick 174 
 
 Producer, Hislop 198 
 
 Producer, Hovine and Breuille 206 
 
 Producer, Humfrey 160 
 
 Producer, Korting's 81 
 
 Producer, Labour Required at 127 
 Producer, La Societe Francais 
 
 de Constructions Mechanique 202 
 Producer, Loomis Water-gas... 99 
 Producer, Loomis-Pettibone 
 
 Water-gas 100 
 
 Producers, Loss of Heat by 
 
 Radiation in 117 
 
 Producers, Loss of Heat in 43, 115 
 Producer, Loss of Heat in 
 
 Ashes 117 
 
 Producer, Lowe Water-gas ... 99 
 Producer, Marechal and Bar- 
 
 riere's 200 
 
 Producer, Mond 87 
 
 Producer, Pintsch 165 
 
 Producers, Quantity of Air and 
 
 Steam Required for 57 
 
 Producers, Rate of Gasifica- 
 tion 114 
 
 Producers, Removal of Ash 
 
 from 119 
 
 Producer, Riche 196 
 
 Producer, Robson 193 
 
 Producer, Rowe and Bickerton 199 
 
 Producer, Schill and Hill 185 
 
 Producer, Shape of 115 
 
 Producer, Siemens 58 
 
 Producer, Smith & Wincott ... 75 
 
 Producers, Solid-bottom 65 
 
 Producers, Sources of Loss of 
 
 Heat in 115 
 
 Producers, Steam and Air 
 
 Required for 57 
 
 Producer, Superheating Air 
 
 and Steam for 115 
 
 Producer, Taylor 79, 171 
 
 Producer, The Blast Furnace 
 
 as a 82 
 
 Producer, Thwaite Duplex ... 123 
 Producer, Thwaite Non-reversal 124 
 Producer, Thwaite Rapid 
 
 Cupola 83 
 
 Producer, Thwaite Simplex ... 62 
 Producer, Thwaite Small- 
 power 75 
 
 Producer, Thwaite Twin 123 
 
 Producer, Tonkin and Puplett 183 
 
INDEX. 
 
 PAGE 
 
 Producers, Using of Coking 
 
 Coals in 120 
 
 Producers, Water-bottom 71 
 
 Producer, Water-gas, at Leeds 
 
 Forge 96 
 
 Producer, Wilson 68, 195 
 
 Producer, Wilson Automatic... 79 
 Producer, Wilson Modified ... 70 
 Producer, Wilson Water- 
 bottom 75 
 
 Products of Combustion, Heat 
 
 Carried Away by .'... 24 
 
 Products of Combustion, 
 
 Volume and Weight of 13 
 
 Puplett (Tonkin and) Producer 183 
 
 Radiation, Heating by 24 
 
 Radiation, Loss of Heat by ... 43 
 Refuse Destroyers as Gas Pro- 
 ducers 150 
 
 Regenerative Furnace, Batho 139 
 Regenerative Furnace, Form 
 
 of Roof 136 
 
 Regenerative Furnace, Gas for 140 
 Regenerative Furnace, Gorman 143 
 Regenerative Furnace, Non- 
 reversing 142 
 
 Regenerative Furnace, Siemens 135 
 Regenerative Furnace, Siemens 
 
 New Form of 141 
 
 Regenerative Furnace, Size of 
 
 Regenerators 139 
 
 Regenerative Furnace, Valves 
 
 for 140 
 
 Regenerative Furnace, Wear- 
 dale 143 
 
 Regenerators for Furnace, 
 
 Size of 139 
 
 Riche, Producer 196 
 
 Rigby (Crossley and) Producer 
 
 187, 188 
 
 Robson Producer 193 
 
 Rowe and Bickerton Producer 199 
 
 Schill and Hill Producer 185 
 
 Sensible Heat of Gases, Utili- 
 sation of 46 
 
 Shape of Producer 115 
 
 Siemens Blower 48 
 
 Siemens Closed-hearth Producer 62 
 
 Siemens Cooling Tube 46 
 
 Siemens Furnace. (See Re- 
 generative Furnace.) 
 Siemens New Form of Furnace 141 
 
 Siemens Producer 58 
 
 Siemens Regenerative Furnace. 
 (See Regenerative Furnace.) 
 Simple Jet 51 
 
 PAGE 
 
 Smith and Wincott Producer... 75 
 Smoke, Decrease of, by the Use 
 
 of Gaseous Fuel 150 
 
 Smoke, Gaseous Fuel 150 
 
 Societe Francais Producer 202 
 
 Solid-bottom Producers 65 
 
 Solid-bottom Producer Con- 
 verted from Siemens 69 
 
 Solid Fuels, Calculating Calo- 
 rific Power of 18 
 
 Specific Heat 9f Gases 22 
 
 Steam and Air for Gas Pro- 
 ducers, Superheating 115 
 
 Steam Boilers, Gas-fired 128 
 
 Steam, Economy Due to Use 
 
 of, in Producer Gas 38 
 
 Steam, Effects of Use of Excess 
 
 41, 86 
 
 Steam in Producer Gas 117 
 
 Steam in Producer Gas, Func- 
 tion of 36 
 
 Steam in Producer Gas, Pre- 
 vention of 36 
 
 Steam Jet. (See Jet.) 
 
 Steam Jet Blower 48, 51 
 
 Steam, Pressure of, Required 
 
 for Producers 57 
 
 Steam, Properties of 5 
 
 Steam, Quantity of, Required 
 
 for Producers 56 
 
 Sulphur in Coal Gas 26 
 
 Tar, Effect of Removing from 
 
 Producer Gas 121 
 
 Tar, Removal of, from Gas by 
 
 Washing 125 
 
 Tar, Removal of, from Pro- 
 ducer Gas 120 
 
 Tarry Matter in Gas 6 
 
 Tate System of Boiler Firing... 132 
 Taylor Revolving-bottom_ Pro- 
 ducer 79 
 
 Taylor Producer 177 
 
 Temperature, Changes of, In- 
 fluence on Volume of Gas ... 9 
 Temperature of Combustion ... 23 
 
 Thermal Units 15 
 
 Thwaite Adj ustable Jet 53 
 
 Thwaite Duplex Producer ... 123 
 Thwaite Non-reversal Producer 124 
 Thwaite Rapid Cupola Pro- 
 ducer 83 
 
 Thwaite Simplex Producer ... 62 
 Thwaite Small-power Producer 75 
 
 Thwaite Twin Producer 123 
 
 Tonkin and Puplett Producer 183 
 Tube for Blowers 55 
 
 Units of Heat 
 
 15 
 
VI. 
 
 INDEX. 
 
 PAGE 
 
 Valves for Regenerative Fur- 
 nace . 140 
 
 Water-bottom Producers 71 
 
 Water in Air 6 
 
 Water Gas 95, 110 
 
 Water Gas, Analyses of 109 
 
 Water Gas, Calorific Power of 109 
 
 Water Gas, Carburising 110 
 
 Water Gas, Cost of 100 
 
 Water-gas Plant, Dellwik- 
 
 Fleischer 102 
 
 Water-gas Plant, Leeds Forge 96 
 
 Water-gas Plant, Loomis 99* 
 
 Water-gas Plant, Loomis-Pet- 
 
 tibone 100 
 
 Water-gas Plant, Lowe 96 
 
 PAGE 
 
 Water-gas Producer, Leeds 
 Forge 
 
 Water-gas Producer, Lowe ... 
 
 Water Gas, Properties of 
 
 Water Gas, Use of, for Boiler 
 Firing 
 
 Water Gas Yield at Leeds 
 Forge 
 
 96 
 99 
 110 
 
 133 
 
 98 
 
 Weardale Furnace 143 
 
 W T eight of Gases, Calculation 
 
 of, from Volume 11 
 
 Wernef (Beanes and) Producer 190 
 
 Whitfield-Duff Producer 125 
 
 Wilson Automatic Producer ... 79 
 
 Wilson Producer 68, 195 
 
 Wilson Producer, Modified ... 70 
 Wilson Water-bottom Producer 75 
 Wincott (Smith and) Producer 75 
 Wood, for Use with Producer 65 
 
ADVERTISEMENTS. 
 
 STEVENSONS, 
 
 PRESTON. 
 
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 . . WITH . . 
 
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 (DUFF'S PATENTS). 
 
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 10,000 H.P. 
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ADVERTISEMENTS. 11. 
 
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ADVERTISEMENTS. 
 
 IV. 
 
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Vll. ADVERTISEMENTS. 
 
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