2203. MCGURL, G. V. (Koppers Co., Inc.). Changing the Composition of a Combustible Gas by Diffusion. United States Patent 2,497,898, Feb. 21, 1950. Chem. Abs., vol. 44, 1950, p. 4230.

When gas appliances are supplied with a mixed gas such as coke oven and water gas, the specific gravity should be maintained as constant as possible. Mixed gases containing a high % of coke-oven gas have too low a specific gravity for satisfactory use in place of the usual mixed gas, owing to the high H₂ content. This can be reduced by diffusion through porous tubes with a gas such as producer gas for the sweep gas. The tubes are made from a Cu screen coated with corrosion-resistant Ni and have 6,400 openings per sq. in. 7 tubes were used, 1.25 in. internal diameter and 24 in. effective length. In 1 example the feed rate of coke-oven gas was 643 ft.³ per hr., this increased on passage through the apparatus to 708 ft.³, 520 ft.³ per hr. of producer gas was used, this decreased to 455 ft.³ The H₂ content of the coke oven gas decreased from 55.6-40.1%, and the specific gravity increased from 0.37-0.538. The H₂ content of the producer gas increased from 10.8 to 29.5, and the specific gravity was reduced from 0.87 to 0.697. By varying the rate of flow of the 2 gases, the relative H₂ contents of the 2 gases can be varied widely as H₂ diffuses much more rapidly than the other gas constituents. The producer gas can thus be converted into a satisfactory gas for Fischer-Tropsch synthesis.