Patent ID: 6494060
Filing Date: 2002-12-17
Classification: F25J,Y10S

Abstract:
A method for producing high purity nitrogen comprising:(A) cleaning feed air in a purification system, passing cleaned feed air into a first column having a top condenser, and producing within the first column by cryogenic rectification first high purity nitrogen fluid and first oxygen-enriched fluid; (B) recovering a first portion of the first high purity nitrogen fluid as product high purity nitrogen; (C) at least partially vaporizing first oxygen-enriched fluid by indirect heat exchange with a second portion of the first high purity nitrogen fluid to produce first oxygen-enriched vapor; (D) turboexpanding first oxygen-enriched vapor to generate refrigeration; and (E) passing refrigeration bearing first oxygen-enriched vapor into a second column having a top condenser, producing within the second column by cryogenic rectification second high purity nitrogen fluid and second oxygen-enriched fluid, passing second oxygen-enriched fluid withdrawn from the second column top condenser to clean the purification system.