A method by which an air stream is separated into oxygen and nitrogen parts has a flow circuit by which no fresh incoming air enters the distillation column

摘要

The air (1) enters a heat exchanger system (4a,4b) and separation columns (6,7) and a portion to a compressor (27) and heat exchanger system (30) from which it cools a heat exchanger (52) for the nitrogen flow (54) from and to the distillation column. The air is returned through the heat exchanger (30).