THE COLLIERY GUARDIAN AND JOURNAL OF THE COAL AND IRON TRADES. Vol. CX. FRIDAY, SEPTEMBER 24, 1915. No. 2856. Gas Producers at Collieries for Obtaining Power and By-Products from Unsaleable Fuel.* By MANSFELDT HENRY MILLS The mining engineer can now find a producer plant capable of dealing with almost any class of fuel con- taining upwards of 50 per cent, of ash, which, under ordinary conditions of combustion, would cake and form hard clinker—in fact, fuel utterly valueless for any other purpose can now be gasified successfully. It has to be remembered that it is one thing to design a producer plant and carry out carefully considered tests under the supervision of highly-trained men, and quite another to carry on the daily work of the producer with varying qualities of fuel and the difficulties of deter- mining the ratio of steam and air blast with the trouble of keeping up an even burning within the producer and all the many little causes that militate against the delivery of a constant supply of high-grade gas. The writer thinks that the following description of the work- ing results of several different types of gas producers will show how all these difficulties are now overcome, and how a large proportion of the power required at a colliery can be generated, using a fair proportion of unsaleable fuel, and how by-products can be recovered, used for furnaces, boiler firing, and the like), or for com- binations of heating and power purposes; also for heat- ing coke ovens, as at the Saltley Gas Works, where inferior coal is used. The class of fuel most commonly used is bituminous slack, but almost any description of fuel can be utilised. Plants are at work generating gas from peat containing up to 60 per cent, of water; raw brown coal; coke and coke breeze; riddlings, or dust coke; wooden blocks; scrub (green wood, cactus, etc.); timber waste and saw- dust; colliery waste (such as belt pickings, washery refuse, etc.); lignite; anthracite. As an average, when using good rough slack, 140,000 cu. ft. of gas will be obtained, and the quantity of Mond gas required to produce an indicated horse-power hour in a large gas engine is about 60 cu. ft. The stand-by losses of a 1,000-horse power Mond producer are about 2 cwt. of fuel per night of 14 hours. When standing eight days the stand-by losses are at the rate of about 7^-lb. per hour, and a large plant can be restarted in a few minutes. ing and condensation of the steam in the blast, and consequent deterioration in the quality of the gas. 5. When clinkering fuel is to be gasified, there must be accessibility to the ash zone for the purpose of removing the clinker; and in any circumstances there must be facilities for evenly removing the ash from the water-sealed bottom, so as to ensure the absolute continuity of operation during the cleaning of the fire which is necessary to maintain uniformity of quality and quantity of gas produced. 6. Provision must be made for the proper distribu- tion of the fuel in the producer, in order that the fuel bed may be maintained at any even thickness to avoid blow-holes, etc. 7. The steam saturated blast should be superheated, and arrangements should be made for the cooling of the lining of the producer round the hot incandescent zone. This is of the greatest importance in by-product recovery plant where gas of the highest heating value is required along with the recovery of a maximum amount of sulphate of ammonia. The cooling of the lining of the producer is also advantageous when highly caking fuels are to be gasified. The writer gives the results of the working of the Mond producer plant with recovery of by-products at Lang- with, Notts, the joint property of the Sheepbridge Coal and Iron Company and the Power Gas Corporation Fig. 1.—Sketch showing various zones of distillation and decomposition. 7OO° to 1,300° Fahr. Decomposition Zone about 1,900° Fahr COtI Combustion Zone about 2.000° Fahr. CO2 Ash Zone 6A8 OUTLET $ i Fig. 3.—Mond producer for non- recovery plant. (Type B). Gas Producers. Fig. 4. —Base of Mond-Trump producer for fuels with high ash content. (Type C). Fig. 2.—Mond producers for by-product and recovery plant. (Type A). Figs. 1 to 4.—Mond in many places, sufficient to repay the whole cost of the fuel; $nd beyond this, there is the inestimable advan- tage of carrying on large industries without polluting the surrounding country with volumes of dense smoke. Mond Gas Producers. There are installations of these producers at the following collieries :—Birchen wood Collieries; Sheep- bridge Company’s Langwith Colliery; Messrs. Pease and Company’s Brick Works, Crook; Brodsworth Colliery, Doncaster; Messrs. Stringer and Jagger’s Colliery, Huddersfield; Nostell Colliery, Wakefield; Denaby Main Colliery, Yorkshire; and Waterloo Main Colliery, Leeds. The Mond plants may be classified under one or other of the two types specified below :— (a) The by-product recovery type, which is made in units of from 500 to 30,000-horse power and upwards, as illustrated in figs. 2 and 4. (5) The non-recovery type, which is made in units of from 100-horse power capacity and upwards, as illustrated in fig. 3. Either description of plants is suitable for power pur- poses (as used in gas engines), for heating purposes (as * From a paper read before the Institution of Mining Engineers. The construction of the producers is shown in figs. 2, 3, and 4. Fig. 2 shows a producer for the recovery of by-products; fig. 3 a producer by which no by-products are recovered; and fig. 4 a system of removing the ash when the ash contents in the fuel are high. There are several different methods of dealing with the ash, one by mechanical grates with automatic removal of the ash. 1. There must be an adequate but not excessive grate area, giving a uniform and effective distribution of the blast to the fuel bed, the angle of incidence of the blast being adjusted to suit the diameter of the producer. 2. A deep bed of incandescent fuel of sufficient thickness to ensure a maximum reduction of the carbon dioxide to carbon monoxide and complete decomposition of the steam. 3. A layer of ashes, resting on the bottom of the producer lute (not on the grate bars), to support the incandescent fuel, and to prevent the escape of unburnt carbon in the water seal. 4. The introduction of the steam saturated blast at a point where it comes into immediate contact with the incandescent fuel zone wilthout passing through the ashes which tend to obstruct its passage—a prac- tice which in some water-sealed producers causes cool- Limited; also descriptions of Mond plants at Denaby Main-Colliery, and of Brodsworth Colliery., Brodsworth Colliery Plant.—There are two producers, each 10 ft. in diameter, one being put down some six years ago, and the second about 12 months ago. The sulphate of ammonia is not recovered, and it is a much simpler plant than that installed at Langwdth. A very good rough slack is gasified, consisting of two-thirds slack (with up to 30 per cent, of ash) and a third nuts, the dust being screened out. Very little ash is made, which is cleaned out once each 24 hours. The air blast is heated by passing down the double shell of the producer before entering the conical fire grate of the producer, the exhaust steam from the blower meeting the air in the grate. The gas passes from the producer to a horizontal cylinder, in which there is a fan or dasher, which gets rid of some of the dust in the gas, and also a little of the tar; the gas then enters a gas holder, from which it is drawn through a sawdust filter, by which the tar is eliminated, after which the gas is cooled by water spray, and passes to the gas engines, which are each of 200- horse power. Though the purification of the gas is simple, it seems to be sufficient; the gas engines work regularly without much trouble from tar, and generate electric power. The