| 摘要 |
Air is separated in a double rectification column 12 comprising a higher pressure rectification column 14, a lower pressure rectification column 16, and a first condenser-reboiler 18. A second condenser-reboiler 20 is operated so as to reboil a liquid fraction obtained in the higher pressure rectification column 12. The second condenser-reboiler 20 is heated by a first stream of compressed air which is thereby partially or totally condensed. (Alternatively, the second condenser-reboiler can be heated by nitrogen-rich vapour pre-separated in a further rectification column operating at an even higher pressure than the column 14.) A second stream of compressed air to be separated is partially or totally condensed in a heat exchanger 26 by indirect heat exchange with a stream of nitrogen condensed in the first condenser-reboiler 18. <IMAGE> |
