Air distillation improvements for high purity oxygen

Abstract

The inefficiency of the nitrogen stripping section of a high purity oxygen-producing air distillation plant is reduced. This allows increased recovery of byproduct argon and in some cases increased recovery of refrigeration work also. The improvement is obtained by evaporating kettle liquid with condensing argon rectifier vapor in two sequential stages, to yield vapor streams respectively having more and less O.sub.2 content than the kettle liquid, and separately feeding them to the N.sub.2 removal column. The improvement is applicable to both dual and triple pressure processes. Referring to FIG. 1, kettle liquid is supplied via valve 11 to the top of contactor 18, and overhead reflux condenser 13 of argon rectifier 14 reboils the bottom of contactor 18. Vapor streams of differing O.sub.2 composition are withdrawn from above and below 18.

Dependencies are inferred from the claim text.