Patent ID: 7380414

Claim:
A method which may be used for treating a liquid bath of oxygen, said method comprising: a) providing a liquid bath in the bottom of a cryogenic distillation column or a column element, wherein: 1) said liquid bath comprises at least about 70 mol % oxygen; and 2) said column or column element forms part of a system of columns that are used for the separation of air; b) boiling continuously a portion of said liquid bath with at least one first reboiler, wherein said first reboiler is made of aluminum; c) purging a portion of said liquid bath, wherein said purging prevents an excessive build up of inflammable impurities in said bath; d) sending said purged portion to at least one second reboiler, wherein said second reboiler is less inflammable than said first reboiler; e) sending oxygen boiled by said second reboiler back to said column; and f) purging a portion of the oxygen rich liquid bath treated by said second reboiler, wherein said purged portion sent to said second reboiler is at least about 10 mol % of said total air stream feeding said system of distillation columns.