Patent ID: 6286336
Filing Date: 2001-09-11
Classification: F25J

Abstract:
A method for carrying out cryogenic air separation comprising:(A) passing feed air into a higher pressure column and separating the feed air by cryogenic rectification within the higher pressure column 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 by cryogenic rectification within the lower pressure column nitrogen-rich vapor and oxygen-rich fluid;(C) withdrawing nitrogen-rich vapor from the upper portion of the lower pressure column, compressing the withdrawn nitrogen-rich vapor wherein at least some of said compression is cold compression, condensing the compressed nitrogen-rich vapor by indirect heat exchange with intermediate liquid from the lower pressure column to produce nitrogen-rich liquid, and passing the nitrogen-rich liquid into the upper portion of the lower pressure column; and(D) recovering at least one of nitrogen-rich vapor, oxygen-rich fluid and nitrogen-enriched fluid as product.