THE DRY PURIFICATION OF COAL GAS
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Moreover, if CS2 were evolved, the lime, acting as a catalytic agent, might account for its partial decomposition into H2S.
Experiments have been conducted in connection with the effect of lime when admixed with coal slack employed in the production of low-grade gases.
At an installation gasifying 100 tons of coal per day, using varying classes of slack from Staffordshire, Nottinghamshire, and Lancashire, an increase of 15 to 20 per cent, of sulphate of ammonia was consistently obtained over a period of two or more years. Similar expeiiments carried out on coal carbonized in a retort house stoked by Fiddes-Aldridge machinery gave the following results :—
Period of test ........... Two weeks Coals carbonized .......... 1,864 tons Slaked lime used .......... 2 per cent.
No increase in the yield of gas per ton was noticeable. Cyanogen content (sodium ferrocyanide) increased from 7-1 Ib. to 10-1 Ib. per 10,000 cubic feet.
Ammonia increase, 3-94 gallons per ton (10 oz.).
Sulphur compounds reduced from 34-6 grams to 12-99 grains per 100 cubic feet.
Sulphuretted hydrogen increased from 2-08 to 2-66 per cent.
The “ Athion ” Process
The “ Athion. ” process has been used to some extent on the Continent, but it has never gained favour in this country. The gas (Fig. 376), after being deprivecL
Fig. 376.—Diagram illustkating the “Athion” Process.
of tar, ammonia, and sulphuretted hydrogen, is washed with a solution of potassium carbonate, in order to effect the complete removal of carbon dioxide. The potassium