February 6, 1914 THE COLLIERY GUARDIAN. 301 50 regenerative ovens, carbonising approximately 300 tons of coal per day, is as follows :— Assuming that each ton of coal yields approximately 11,000 ft. of gas per ton, half of which is surplus, and that large gas engines use, say, 21 ft. per brake-horse- power, then —9 x — 3,275-brake horse-power ; or, 21 x 24 r taking steam engines, 5,500 cubic feet of gas of 450 British thermal units available per ton of goal gasified = 2,475,000 British thermal units. A good gas burner with boilers will give an efficiency of 75 per cent., BLOWERS DUCT -CATCKCP SAWDUST PU7UHCR DUOrCATCHER Big. 2.—Ground Plan of Littleton Colliery 700-horse power Gas Plant. a South Yorkshire battery of Koppers ovens at the Cortonwood Colliery, the following are the results obtained:— Coke ................. 71 per cent, of coal carbonised. Tar ................... 5*5 Sulphate of ammonia... 1’5 „ „ ,, Benzol................ 2| gallons per ton of coal. Total gas............. 11,760 cubic feet per ton of coal carbonised = 6 135 cubic feet of surplus gas per ton. These are excellent results, but the writer is sorry to say that collieries do not make such use of the surplus gases as they might do. In many cases their gases are burned under boilers, and the power that could be developed from them is only utilised in part. started to work at the Wharncliffe Silkstone Collieries on gas of a calorific value of 435 British thermal units for generating electricity. The owners of these collieries have also one of Mather and Platt’s two-cycle engines of 300-horse power for driving the ventilating fan, one 350-horse power Robey, two 200-horse power vis a vis Stockport engines generating electricity for under- ground purposes, and a 75-horse power Crossley engine producing current for lighting. Here 44 Simon-Carves ovens are found to produce surplus gas for about 1,000- horse power. At Mitchell Main Colliery two Hornsby engines are working with excellent results on gas from Simon- Carves ovens, one being of 100 and the other of 300-horse power. At Messrs. Newton, Chambers and Co.’s Rockingham Colliery two Mather and Platt horizontal two-cycle engines of 500-horse power each, working on gas from Koppers ovens, are producing electric current for distribution to some of the outlying pits of the company. B^The use of gas-producer plant at collieries has so far made very little progress, but there is no doubt that as the advantages of this class of plant become better known, there will be a big future for both these and gas engines actuated by this gas. So far back as 1908, Messrs. Mather and Platt installed two 750-horse power engines at a colliery in South Wales to work from producer gas, but without recovery of sulphate of ammonia. Amongst later installations the most important is the plant put down at Birchenwood Colliery, Staffordshire, for Messrs. Robert Heath and Sons Limited, a brief description of which is as follows :—The plant comprises 13 Mond gas producers, fitted with Trump mechanical tables for dealing with 320 tons of mixed waste fuels (coal, shale, &c.) per day. This fuel contains about 40 per cent, of ash. The winding, pumping, com- pressing, and other engines and machinery at the collieries require steam from 18 Lancashire boilers, with a maximum evaporation rating of 7,0001b. each per hour. To obtain this steam, burgie, which is stated to cost 6s. 9d. per ton, is consumed to the extent of 48,000 tons per annum. The pits produce refuse as follows : — Belt pickings, 50 tons per day ; washing refuse, 90 tons per day. These fuels alone are insufficient and of too poor a quality to produce gas for the 18 boilers with a sufficent return in sulphate of ammonia to warrant their gasification alone. The scheme therefore provides for an admixture of these with burgie in approximately the following properties: burgie, 19 parts; belt-pickings, 5 parts ; and washing refuse, 9 parts. These, on a total consumption of 320 tons per day and on a conservative estimate, will provide gas sufficient to evaporate 12,600 gallons of water per hour, or 700 gallons in each of the 18 boilers. Moreover, there will be recovered from the gas 70 lb. of sulphate of ammonia per ton of fuel, which is taken as worth £10 per ton (although the market price is considerably higher). Analyses of the above- named fuels are given in Table II.:— Fig. 3.—Section of Galloway Erhardt-and-Sehmer Gas Engine. leaving 1,856,000 British thermal units available for evaporation. To heat and evaporate 11 lb. of water from 80 degs. Fahr, to 150 lb. per square inch will take 1,145 British thermal units, equal to 1,620 lb. of steam per ton of coal carbonised. Taking a good steam turbine, say 11 lb. of steam per brake-horse-power hour, equal to 147 brake-horse-power , p 147 X 300 per ton of coal,----------- 24 — 1,837 - brake - horse - power. The efficiencies given are, of course, approximate, as no allowance has been made for radiation. The writer has endeavoured to put the steam side of the comparison in a mo t favourable light, but he might mention that at one colliery with which he has had to deal, eight times the power is obtained with gas engines that was previously developed by steam engines from the same amount of gas : both the gas and the electricity are measured. These figures are approximate, as the gas varies according to the class of coal used. To take Typical Colliery Gas-plant Installations A typical colliery installation, consisting of three 600-brake horse-power National engines, coupled to alternators, is that at the Midland Coal, Coke and Iron Company’s works at Apedale, Staffordshire. The first of these engines has been at work for about three years, and has given no trouble. The gas is passed by blowers through purifiers, the oxide for these being supplied free of charge by a firm of chemical manufacturers who take back the saturated oxide, and reimburse themselves by extraction of the sulphur. At the present time the National Gas Engine Company have three engines more on order for this company to work upon blastfurnace gas. Two of these are to be direct-coupled to Alley and McLellan air-compressoi s, and one to an alternator generator. Two similar ei g'ues, each of 500-horse power, are also working at the adjoining Talk-o’-th’-Hill Colliery, from which the interesting results contained in Table I. have been obtained. A 1,000-horse power National engine has recently Belt pickings. Moisture percent. — ... 15’50 .. . 2’60 Ash „ 19’50 ... 6070 .. . 47’16 Volatile matter „ 29’10 ... 17’00 .. . 18’35 Nitrogen „ 1’40 ... 0’68 .. . 1’06 Total carbon ... „ 64’50 ... 26’73 .. . 37’05 Fixed carbon ... „ 49’05 ... 13’76 .. . 29’68 Calorific value in British thermal units ... 11,550 ... 5,212 .. . 7,700 The Birchenwood Colliery Company’s first object was to utilise their waste products which are combustible in an ordinary boiler furnace only by admixture with other fuel, involving difficulties in stoking and reduced steam output. The Power Gas Corporation did not care to gasify any mixture which contained on an average over 40 per cent, of ash. earlier tests having shown that such a course would lead to considerable difficulties in man- agement of the producers. It was held desirable that all the boilers should work under like conditions, and these points led to the determination of a mixture which