Taylor gas-producer.
R. D. Wood & Co., Philadelphia.
A Gas Producer.
Producer gas is in more extensive use than water-gas. It is evolved in apparatus of many good designs: let us glance at the Taylor gas producer built by R. D. Wood & Company, Philadelphia. Its fuel enters in a steady stream, in controlled quantity, through a Bildt automatic feed which has a constantly rotating distributor with deflecting surfaces. The incandescent fuel is carried on a bed of ashes several feet thick, so that the coal gradually burns out and cools before its ashes are discharged. Through a conduit an airblast is carried up through this layer of ashes to where the fuel is aglow; united with this airblast is a pipe admitting steam; the united air and steam are emitted radially. In the producer walls are sight or test holes so placed that the line dividing ashes from glowing fuel may at any time be observed. When this line becomes higher on one side than the other, scrapers, duly arranged, are used. At the bottom of the producer is a Taylor rotative table which grinds out the ashes as fast as they rise above the desired depth, say every six to twenty-four hours, according to the rate of working. In large producers the ash bed is kept about three and a half feet deep, so that any coal that may pass the point of air admission has ample time to burn entirely out: in a producer with an ordinary grate such coal would fall wastefully into the ashpit. As the Taylor ash table turns it grinds the lower part of the fuel bed, closing any channels formed by the airblast, and restraining the formation of carbon dioxide, a useless product, to a minimum. A few impulses of the crank at frequent intervals maintain the fuel in solid condition, reducing the need of poking from above.
Other American producers differ from the Wood apparatus in details of design and operation; in principle all are much alike. Any good producer works well with cheap fuels, bituminous coals of inferior quality, culm, lignite, wood, peat, tanbark, and even straw from the thresher. With each of these there must be due modification of mechanism, together with means of forcing air and steam into the fire. A suction plant may be employed when superior fuels are burned, coke, anthracite, or charcoal; with currents of air and steam automatically drawn into the producer, the surrounding room is not likely to be filled with the harmful gases which may be occasionally ejected by a pressure plant.
Mond Gas.
England has gas-power installations much larger and more elaborate than those of America. Of these the most extensive have been built by the Power-gas Corporation in London, under the patents of Mond, Duff and Talbot. A Mond plant yields a gas having 84 per cent. of the calorific value of the coal consumed, which may be slack at six shillings, $1.46, per ton. Where more than thirty tons of coal per day are used, it is worth while intercepting the sulphate of ammonia, amounting to 90 pounds per ton of coal, which in small producers cannot readily be seized. Mond gas is free from tar, is cleansed of soot and dust, and holds less sulphur than ordinary producer gas. Operation is simple enough: first of all the slack is brought into hoppers above the producers. From these it is fed in charges, of from 300 to 1,000 pounds, into the producer bell, where the first heating takes place: the products of distillation pass downward into the hot zone of fuel before joining the bulk of gas leaving the producer. This converts the tar into a fixed gas, and prepares the slack for descent into the body of the producer, where it is acted upon by an airblast saturated with steam at 185° Fahr., and superheated before coming into contact with the fuel. The stream of hot gases from the producer now traverses a washer, a rectangular iron chamber with side lutes, where a water spray thrown by revolving dashers brings down the temperature of the gases to about 194° Fahr. In plants which recover the ammonia sulphate, the gas takes its way through a lead-lined tower, filled with tiles of large surface, where it meets a downward flow of acid liquor, circulated by pumps, containing ammonia sulphate with about 4 per cent. excess of free sulphuric acid. Combination of the ammonia with this free acid ensues, yielding still more ammonia sulphate. The gases, freed from their ammonia, are conducted into a cooling tower, where they meet a descending shower of cold water effecting a further cleansing before the gases enter the main pipe for delivery to consumers. In its general plan, a Mond plant resembles an illuminating gas works, especially in its seizure of profitable by-products. A ton of slack costing in England $1.46 yields 90 pounds of ammonia sulphate worth $1.92 or thereabout.[40]
[40] “Producer-gas and Gas-producers,” by Samuel S. Wyer, is a treatise of value, fully illustrated. New York, Engineering and Mining Journal, 1906. $4.00.
Blast Furnace Gases.
For many years flames from blast furnaces and coke ovens testified to the waste of valuable gases, in especial the combustible carbon monoxide which is the main ingredient in producer gas. When we learn that coal or coke in iron-smelting parts with but three per cent. of its heat to the ore, we begin to see how grievous was the waste so long endured. For a few years past the gases sent forth from blast furnaces have been employed to heat the incoming air for the blowers, and to raise steam for engines. With twice the efficiency of steam motors the gas engine renders it well worth while to rid furnace gases of their dust and dirt so that they may not injure the mechanism they impel. An effective cleanser acts by separating the gases from their admixtures by centrifugal force. At the Lackawanna Steel Works, Buffalo, N. Y., eight gas-engines, each of 1,000 horse-power, are run on blast furnace gases. It may well prove that installations of this kind will bring other blast furnaces into cities where the sale of electricity will form a large item in the profits.
