GB697327A - Process for cooling and purifying gas mixtures - Google Patents

Abstract

697,327. Separation of air. GES. FUR LINDE'S EISMASCHINEN AKT.-GES. Sept. 18, 1950 [Nov. 10, 1949; Nov. 10, 1949; March 9, 1950; March 25, 1950], No. 22862/50. Class 8 (ii). Cooling of a gas mixture, e.g., air and removal of readily condensible impurities therefrom, e.g. carbon dioxide and ethylene, prior to separation in a double column 8, Fig. 1, is effected by dividing the air into main currents which are cooled and purified by passage throughout the whole length of alternating heat exchangers or cold accumulators 1..4 traversed also throughout their lengths by reversely flowing cold separated nitrogen and oxygen and into a subsidiary current or currents from which impurities are absorbed. e.g., by passage through alternating silica-gel containers 6a, 6b. The subsidiary current comprises a smali percentage of the mixture entering an inlet 10, and after compression to 15 atmospheres at a compressor 80 is cooled in alternating driers 5a, 5b, which together with the adsorbers 6a, 6b are cooled by an ammonia circuit: the current traverses a liquefier 7 before entering a high pressure column 21. A major portion of the cold main current enters the column 21 and the remainder traverses the liquefier 7 and an expansion turbine 24 before entering the low-pressure column 25. In a modification the subsidiary current branches from part way down the cold accumulators before traversing the adsorbers, and the latter are regenerated by warmed returning nitrogen. In a further modification the adsorbers 13 ... 16, Fig. 5, are embedded in the accumulators and the subsidiary currents leaving by pipes 17, 70, and joined if desired by a portion of the main streams in a pipe 46 are heated in an exchanger 39, compressed at a compressor 40, cooled in exchangers 39, 42, traversed by cold main air, and fed in the liquid state to the column 21; the main current from exchanger 42 being expanded in the turbine 24 and fed to the column 25. In a further modification the subsidiary current branched from the nitrogen regenerators 1, 2, Fig. 6, at pipes 30, 30a, and traversing adsorbers 33, 37, and the compressor 40 heats nitrogen from the column 21 in the exchanger 42, the nitrogen being expanded in the turbine 24 before traversing the regenerators.