Verfahren zur Verfluessigung eines Gases

842,471. Liquefaction and rectification of gases. SOC. L'AIR LIQUIDE, SOC. ANON. POUR L'ETUDE ET L'EXPLOITATION DES PROCEDES G. CLAUDE. Aug. 20, 1957 [Sept. 7, 1956], No. 26275/57. Class 8(2). Liquefaction prior to rectification of a gas such as deterium-containing hydrogen incapable of liquefaction by free expansion starting from room temperature is effected by forcing a first portion of said hydrogen by a compressor 3 through a first heat exchnager 11 in countercurrent flow with an equal flow of rectified hydrogen, then through a second exchanger 19 cooled by a smaller flow of rectified hydrogen, expanding with external work in an engine 29 and thereafter liquefying in an exchanger 33 in countercurrent flow with liquid hydrogen from the rectification column (not shown) to which the so liquefied crude hydrogen is fed through a duct 37 ; a second portion of hydrogen being forced by a compressor 2 through a heat exchanger 8 in countercurrent flow with an equal amount of rectified hydrogen, then through a second exchanger 12 cooled by a larger flow of rectified hydrogen and finally through the exchanger 33 before free expansion at a valve 16 from which liquid hydrogen passes through a duct 18 to the rectification column. As shown the second portion of gas to be liquefied comprises pure hydrogen to serve as reflux and nitrogen impurity is removed from the deterium-containing hydrogen by absorption chambers 23A, 23B after which the nitrogen-free gas is passed reversely through the exchanger 19 to raise its temperature from -230‹C to -175‹C prior to expansion in engine 29. In a modification the expansion engine is provided in the pure hydrogen circuit after the second heat exchanger thereof.