Patent ID: 6626008
Filing Date: 2003-09-30
Classification: F25J

Abstract:
A method for producing low purity oxygen comprising:(A) passing feed air into a higher pressure column and separating the feed air within the higher pressure column by cryogenic rectification into nitrogen-enriched fluid and oxygen-enriched fluid; (B) passing nitrogen-enriched fluid and oxygen-enriched fluid from the higher pressure column into a lower pressure column and producing oxygen-richer fluid by cryogenic rectification within the lower pressure column; (C) passing oxygen-richer fluid into the upper portion of an auxiliary column and producing low purity oxygen fluid in the lower portion of the auxiliary column; (D) withdrawing reboiling fluid from an intermediate level of the higher pressure column, increasing the pressure of the withdrawn reboiling fluid by cold compression, and vaporizing a portion of the low purity oxygen fluid by indirect heat exchange with the increased pressure withdrawn reboiling fluid; and (E) recovering low purity oxygen fluid from the lower portion of the auxiliary column as product low purity oxygen.