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US 6,622,520 B1Granted
Cryogenic rectification system for producing low purity oxygen using shelf vapor turboexpansion
AssigneePraxair Technology, Inc.
InventorsNeil Mark Prosser, Minish Mahendra Shah
Life of this patent
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Abstract
A cryogenic rectification system for producing low purity oxygen from an auxiliary column to a double column system and which can also effectively produce nitrogen gas product and/or one or more liquid products wherein the lower pressure column of the double column system is reboiled in part by turboexpanded shelf vapor which is condensed in an intermediate reboiler and preferably subcooled prior to passage into the lower pressure column.
Claims17
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 vapor and oxygen-enriched liquid;
- (B) passing oxygen-enriched liquid into a lower pressure column, condensing a first portion of the nitrogen-enriched vapor, and passing at least some of the resulting condensed first portion nitrogen-enriched liquid into the higher pressure column;
- (C) turboexpanding a second portion of the nitrogen-enriched vapor, condensing the turboexpanded second portion of the nitrogen-enriched vapor, and passing the condensed second portion nitrogen-enriched liquid into the lower pressure column;
- (D) producing by cryogenic rectification within the lower pressure column nitrogen-richer vapor and oxygen-richer liquid, and passing oxygen-richer liquid from the lower pressure column into an auxiliary column;
- and
- (E) producing by cryogenic rectification low purity oxygen within the auxiliary column, and recovering low purity oxygen product from the lower portion of the auxiliary column.
3 more elements
Apparatus for producing low purity oxygen comprising:
- (A) a higher pressure column, a lower pressure column having a bottom reboiler and an intermediate reboiler, and means for passing feed air into the higher pressure column;
- (B) means for passing fluid from the lower portion of the higher pressure column into the lower pressure column, means for passing fluid from the upper portion of the higher pressure column to the lower pressure column bottom reboiler, and means for passing fluid from the lower pressure column bottom reboiler to the higher pressure column;
- (C) a turboexpander, means for passing fluid from the upper portion of the higher pressure column to the turboexpander, means for passing fluid from the turboexpander to the lower pressure column intermediate reboiler, and means for passing fluid from the lower pressure column intermediate reboiler into the lower pressure column;
- (D) an auxiliary column and means for passing fluid for the lower portion of the lower pressure column to the upper portion of the auxiliary column;
- and
- (E) means for recovering low purity oxygen product from the lower portion of the auxiliary column.
3 more elements
Dependencies are inferred from the claim text.