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US 4,962,646 AGranted
Air separation
AssigneeThe BOC Group, Inc.
InventorThomas Rathbone
Life of this patent
Estimating the term…
Abstract
A method and apparatus for cryogenic air separation wherein both fuel gas and electrical power are produced. Respective operating pressures of the lower and higher pressure rectification columns can be set independently of one another, allowing flexibility in selecting the purity of the oxygen product.
Claims22
A method of air separation comprising:
- (a) removing carbon dioxide and water vapour from a compressed air feed stream and reducing the temperature of the feed stream to a level suitable for its separation by rectification at cryogenic temperatures;
- (b) introducing the air stream into a higher pressure rectification column, providing liquid nitrogen reflux for the higher pressure rectification column, and separating the air therein into oxygen-enriched and nitrogen-enriched fractions;
- (c) withdrawing a stream of nitrogen-enriched fluid from the higher pressure column;
- (d) withdrawing a stream of oxygen-enriched liquid from the higher pressure column and passing it into a lower pressure rectification column in which it is separated into oxygen and nitrogen fractions;
- (e) withdrawing an oxygen stream and a nitrogen stream from the lower pressure rectification column;
- and
- (f) operating a heat pump cycle to provide reboil for the lower pressure rectification column and reflux for both rectificatiion columns.
4 more elements
An apparatus for separating air comprising:
- (a) a compressor for compressing a feed air stream;
- (b) means for separating carbon dioxide and water vapour from the feed air stream;
- (c) heat exchange means for reducing the temperature of the air stream to a level suitable for separation by cryogenic rectification;
- (d) a higher pressure rectification column in communication with the lower temperature end of a passage through the heat exchange means for the air stream, the higher pressure rectification column having an inlet for liquid nitrogen reflux, an outlet for a nitrogen stream and another outlet for an oxygen-enriched liquid stream;
- (e) a lower pressure rectification column having an inlet in communication with the said outlet for the oxygen-enriched liquid stream and having outlets for separate oxygen and nitrogen streams;
- and
- (f) a heat pump circuit for producing reboil for the lower pressure rectification column and reflux for both rectification columns.
4 more elements
Dependencies are inferred from the claim text.