GB677299A - Improved low temperature process and apparatus for separating gas mixture - Google Patents

Abstract

677,299. Separation of air. LINDE AIR PRODUCTS CO. May 19, 1950 [May 20, 1949], No. 12553/50. Class 8 (ii) The elimination of higher boiling point impurities from a substantially binary gas mixture e.g. air prior to its rectification in a column 32, 37 at low temperature and following cooling of the compressed air in regenerators 12, 121, 14 141 is effected by passing the cooled air through ducts 16, 17, 18 into a chamber 19 where it is scrubbed with liquid formed by liquefaction of air in tubes 49 cooled by effluent nitrogen product passing from the column 37 through ducts 44, 47 and the scrubber liquid is freed from impurities e.g. by a carbon dioxide filter 71, and the warmed nitrogen is passed through the exchanger under regeneration to a delivery duct 51. More scrubber liquid is provided by liquefying scrubbed gas in heat exchange tubes 59 cooled by oxygen gas from a vaporizer 54 supplied with gas and liquid through valved ducts 52, 56 ; the warmed oxygen gas passing through a duct 60 to one or other of the regenerators 14, 141 and a delivery duct 61. Scrubbed unliquefied air leaving the tubes 49, 59 through ducts 68, 69 is joined by scrubbed air in a duct 63, and a minor portion of the combination is liquified in a vaporizer condenser 55 and returned as scrubber liquid to the chamber 19, whilst the remainder is fed to the base of column 32. Scrubbed air also passes from the chamber 19 through a duct 27 and one or other of exchangers 23, 231 where it is warmed by indirect countercurrent heat exchange with partly cooled air tapped at ducts 21 from near the base of the regenerators. The warmed scrubbed air is expanded at a turbine 29 and is joined by_ a portion of returning nitrogen in the duct 47 before being fed through a duct 30 into the column 37. In a modification warming of the scrubbed air prior to its expansion in the turbine 29 is effected by passing it through coils arranged in parallel near the base of each regenerator 12, 121, 14, 141, and the expansion cold is in part used to further cool the scrubbed gas being fed to the base of the column 32.