GB671859A - Process of and apparatus for separating gas mixtures containing higher-boiling impurities - Google Patents

Abstract

671,859. Air separation. LINDE AIR PRODUCTS CO. May 5, 1950 [May 20, 1949]. No. 11226/50. Class 8 (ii) A process for the low temperature separation of a gas mixture e.g., air containing higher boiling point impurities comprises cooling the air at a condensation pressure below 125 p.s.i. e.g., in reversible regenerators 10, 11, passing a first stream through ducts 15, 16, 17 to a chamber 18 where it is scrubbed free of residual impurities and passing the cleaned gas through a duct 22 to a rectification apparatus D e.g., the high pressure stage 23 thereof, passing a second stream of air cooled in the regenerators to a temperature higher than the first stream through ducts 60, 62, 57 to one or other of solid impurity removers e.g., filters 66, expanding with the production of external work e.g., at a turbine 54 and using a portion of the resulting cold together with that of a least the effluent nitrogen from the head of the low pressure column 29 to effect liquefaction of a portion of the cleaned first stream by traversing a coil 38, and using the remainder of the cold for cooling the incoming air. In the production of gaseous oxygen, impurity bearing liquid air from the scrubber 18 after traversing one or other of filters 20 is fed to the low pressure column 29 as reflux, and the major portion of the clean gas is led to the base of the column 23, the remainder being condensed in a chamber 45 and returned to the scrubber 18. Liquid oxygen from the base of the column 29 is vapourized in a chamber 43, and after traversing a coil 50, a duct 51 and the exchanger 11 under regeneration, is delivered by a valved duct 52. The filters 66 are charged with silica gel which also absorbs vapours, and if desired the air expanded and cooled by the turbine 54 traverses one or other of filters 71 before passing to the column 29. The said second stream may also comprise cleaned air from the scrubber 18 which after traversing a duct 55 is warmed by incoming air in ducts 63 whereupon it joins the gas in duct 57. Carbon dioxide deposited in ducts 63 and filters 20, 66, 71 is sublimed by reverse flow of warm gas. In a modified process for the production of liquid oxygen, which is trapped from the base of the low pressure column, a portion of the cleaned first stream leaving the scrubber is mixed with the second stream leaving the regenerator in such proportions that the resulting temperature provides high efficiency of refrigeration on turbine expansion after filtration.