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.