| 摘要 |
A cryogenic prodn. of nitrogen is effected by introducing feed air into a main rectification column operating at 35-245 psia to give a nitrogen rich vapour and an oxygen enriched liq. A minor portion of the feed air is introduced into a high pressure sepn. column. At least part of the nitrogen enriched vapour is condensed by indirect heat exchange with the oxygen rich fraction and this is fed back to the column as reflux liq. at a point above the level where the feed air is introduced. This allows a nitrogen rich product stream to be recovered. High purity nitrogen can be extracted while allowing a sufficiently high level of reflux.
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