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US 4,560,397 AGranted
Process to produce ultrahigh purity oxygen
AssigneeUnion Carbide Corporation
InventorHarry Cheung
Life of this patent
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Abstract
A process for the production of ultrahigh purity oxygen and elevated pressure nitrogen by the cryogenic rectification of air wherein the product oxygen is recovered from a secondary column at a point above the liquid sump while impurities are removed from the column at a distance from the product withdrawal point.
Claims33
A cryogenic air separation process for the production of elevated pressure nitrogen, and ultrahigh purity oxygen containing no more than 100 ppm of impurities, comprising:
- (A) introducing cleaned cooled feed air into a primary column operating at a pressure in the range of from 40 to 200 psia;
- (B) separating said feed air in said primary column into a nitrogen-rich vapor and an oxygen-rich liquid;
- (C) recovering a first portion of said nitrogen-rich vapor as elevated pressure nitrogen gas;
- (D) providing reflux liquid for the primary column;
- (E) introducing a first portion of said oxygen-enriched liquid as feed into a secondary column operating at a pressure in the range of from 15 to 75 psia;
- (F) separating said feed in said secondary column into a vapor fraction and a liquid fraction;
- (G) withdrawing a first portion of said liquid fraction from said secondary column;
- (H) vaporizing a second portion of said liquid fraction to provide reflux vapor for said secondary column;
- (I) withdrawing a vapor stream from said secondary column at a point above at least one equilibrium stage above the vaporizing second liquid portion of step (H);
- and
- (J) recovering said withdrawn vapor stream as product ultrahigh purity oxygen generally suitable for use in such as the electronics industry and having no more than 100 ppm of impurities.
8 more elements
Dependencies are inferred from the claim text.