Nitrogen liquefaction with plural work expansion of feed as refrigerant

摘要

1,099,669. Gas liquefaction process. AIR REDUCTION CO. Oct. 7, 1966 [Oct. 8, 1965], No. 44923/66. Heading F4P. Liquefaction of a gas, e.g. effluent nitrogen from the low pressure column (103), Fig. 6 (not shown), of a two stage air rectification plant is effected by compression to not more than 2À5 times the critical pressure of the gas at 151, 153, 155, 157, 159, 163, 166 cooling in means including paths a, a1 of a first heat exchanger 169, dividing the cooled gas at 186 into a minor portion which is cooled without liquefaction in path a of a second exchanger 192 and into a major portion which is work-expanded in turbines 188, 194, with intervening warming in a path a of exchanger 192 from which latter the cooled minor portion is passed through a line 203 and is throttle-expanded at 204, 209, 213 into a product liquid storage vessel 213; uncondensed vapour from the latter being forced by a pump 217 through paths c of exchangers 192, 169 and a line 221 to the compressor inlets where it is joined by the work expanded major portion. The compressed feed gas is withdrawn from path a of exchanger 169 cooled by external refrigeration means 175 and is then returned to path a of exchanger 169. Throttle valve 204 discharges into a separater 206 which also condenses oxygen. Vapour above liquid oxygen storage vessel 112 and a portion of condensed nitrogen is passed along a line 122 to provide additional reflux for the column (103).