Patent ID: 6460373
Filing Date: 2002-10-08
Classification: F25J

Abstract:
A method for producing high purity oxygen comprising:(A) passing feed air at a feed level into a first column and producing by cryogenic rectification within the first column first nitrogen-rich fluid and first oxygen-enriched fluid; (B) passing first oxygen-enriched fluid from the first column at a feed level into a second column having a top condenser, and producing by cryogenic rectification within the second column second nitrogen-rich fluid and second oxygen-enriched fluid; (C) passing oxygen-containing liquid taken from above the feed level of at least one of the first column and the second column into the upper portion of a third column and down the third column countercurrently to upflowing vapor to produce high purity oxygen fluid; (D) vaporizing a first portion of the high purity oxygen fluid by indirect heat exchange with at least one of feed air and first nitrogen-rich fluid to produce said upflowing vapor; and (E) recovering a second portion of the high purity oxygen fluid as product high purity oxygen.