GAS-PRODUCERS, GAs-FuEL.—The increasing use of various kinds of gas as fuel. both in the industrial arts and for domestic purposes. makes important a knowledge of the different processes for producing fuel-gas, and of the heat-giving power of the several kinds. An elaborate study of this subject is given in a paper by W. J. Taylor, read before the Amer ican institute of Mining Engineers. February, 1800 (Transactions, vol. xviii).
"The extravagant claim," says Mr, Taylor, "of some oil-gas advocates is still heard, that by vaporizing oil with steam and then passing the mixture through a coil of hot iron pipe, an oil-water-gas containing 20,600 heat-units is formed from 1 lb. of oil carrying originally 21, 000 heat-units, while the only energy expended on the gas has been by the introduction of a little steam and a little extraneous heat. Theoretically, 1 lb. of oil converted into water-gas carries 20000 heat-units, but this is only obtainable by a large expenditure of energy, the amount of which is difficult to calculate; even with apparatus of theoretically perfect effi ciency, it could not be less than the quantity of heat added to the calorific energy of the oil. The cheapest artificial fuel-gas per unit of heat is common producer-gas, or "air-gas," as it might he termed, since the oxygen for burning carbon to carbon monoxide is derived mainly from air. The associated atmospheric nitrogen dilutes the carbon monoxide. making air-gas the weakest of all useful gases—that is. the lowest in combustible, both by weight and by volume. Next in the order of heat-energy comes water-gas, in which the oxygen for com bining with carbon to form carbon monoxide is derived from water-vapor, and hydrogen is liberated. For equal volumes, this gas has more than double the calorific power of air-gas. Third in the ascending scale stands coal-gas, the ordinary illuminating gas distilled from bituminous coal, which carries more than double the heat-energy of water-gas. Last, and highest in the list, is natural gas, which we can not duplicate in practice by any known pro cess. The ealorifie power• of natural gas is about 50 per cent greater than that of coal-gas. The introduction of natural gas for metallurgical purposes has largely stimulated the pro duction and use of artificial gas made from coal and from oil, if the vapors of the latter can be fairly considered a gas."
7'he Loomis Gas Process.—This process was introduced in 1887, and has come into ex tended use in the United States and Europe, producing gas for fuel and illuminating pur poses from bituminous slack coal, anthracite screenings, and other low-cost fuels. Essentially a water-gas process, the producer or blast-gases of excellent quality are successfully applied to industrial work, making in combination with the water-gas a very economical fuel-gas plant. Fuel-gas made by this process is being distributed in cities and towns for domestic uses. and is applied to a great variety of in dustrial work, such as steel-melting, melting iron, lirass, copper, silver, and other metals, tube and plate welding, smiths' forges, re heating, hardening, tempering, and annealing furnaces. pottery kilns, etc. For illuminating purposes the water-gas is either ear buret ed or the non-luminous gas used with incandescent burners, sneh as the Welsbaeh, Figs. 1 and 2 show sections of the genera tor, which is a cylindrical iron or steel shell 7 to 10 ft. in diameter, and from 12 to 14 ft. in height, lined with fire-brick. a is the top door for feeding fuel and supplying air for combustion, (1 is the water-gas outlet. J/ and X cleaning doors. b tire-brick arches for grate, passage for produce•-gas to cooler. Figs. 3 and 4 sent complete plant of two generators. Willi fire in the genera the exhauster D draws air into the top door a down through the lied of fuel, the resultant producer-gas laing drawn up through the vertical cooling-Inffier r to the exhauster. and by it delivered into the iiroducer-ges holder. When the fuel is in a state of in candescence the top door rt is closed, and the blast stopped by ('losing the valve B: steam being admitted at 'lasses lip through the hot carbon. the resultant water-gas passing mit at the top of the generator through the seal and scrubber• G to the water-gas holder. Producer-gas can he made eontimionsly, and enriched by steam into the top of the generator•. The quantity of water and producer gas varies with the kind and quality of the fuel used and the inctliod of operating. The average make is from 3:1. 000 to 43.0nn enb, ft. of water-gas, and from 100,000 to 130,000 cub. ft. of producer-gas, from a ton of coal.