| 摘要 |
Air is introduced into a fractionation system including one or more columns (3, 4). A liquefied product stream (11, 15) is extracted. This is introduced into an evaporator (17), where it is evaporated by indirect heat exchange, and a gaseous product (18) is withdrawn. Fluid (19) is recirculated around a closed circuit (23, 26-31) in which it is compressed (20), liquefied in the evaporator, and returned again to the compressor. The liquefied recirculated fluid (23) is evaporated downstream of the compressor by indirect heat exchange with a condensing, heating fluid (34, 36) in a condensing evaporator (25). Preferred features: The recirculated fluid is an air component or a mixture of them, preferably nitrogen or air. Heating fluid (37) condensed in the condensing evaporator is introduced into one or more the fractionating columns. Heating fluid (34, 36) is extracted from one or more of the separation columns before its introduction into the condensing evaporator. Some of the compressed fluid (22) is expanded to produce power (33) and returned (29, 31, 19) to the compressor. The condensing evaporator is operated as a falling film evaporator.
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