| 摘要 |
1,245,621. Cold separation of air. HYDROCARBON RESEARCH Inc. 5 Dec., 1968 [5 Jan., 1968], No. 57863/68. Heading F4P. In a compressed air rectification process wherein feed air in a line 14, Fig. 1, is cooled in reversing heat exchanger 16, 18 traversed by cold effluent nitrogen and oxygen withdrawn from the low pressure stage 32 of a conventional double column to the high pressure stage 22 of which cold feed air is fed through a line 20, part of the cold requirements of the process are met by withdrawing at 44 high pressure nitrogen stream from column 22, warming it in exchanger 18 to a temperature between ambient and the lowest temperature of the process, further warming the compressed nitrogen stream to ambient temperature in heat exchange with itself after compression at 54 and aftercooling at 56 and finally expanding in a turbine 60. As shown the further warming of the withdrawn compressed nitrogen to ambient temperature is effected in a heat exchanger 52, but in a modification, Fig. 2, said further warming is effected in heat exchanger 16 in countercurrent with itself after compression at 54 and aftercooling at 56. The cold nitrogen leaving turbine 60 is added to effluent low pressure nitrogen in a line 27 prior to its passage through exchangers 16, 18.
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