摘要 |
A system for separating air by cryogenic rectification whereby liquid production is increased by employing two separate turboexpanders (14, 24), one which (14) exhausts at a pressure no higher than that sufficient to feed the lower pressure column (42), the other which (24) exhausts at a pressure no lower than that sufficient to feed the higher pressure column (40), and wherein one of the turboexpanders (24) is fed with ambient temperature or modestly cooled feed air and preferably operates intermittently depending upon whether greater or lesser amounts of liquid product are desired. |