Air separation
AssigneeThe BOC Group, Inc.
InventorJohn Douglas Oakey
Life of this patent
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Abstract
Air is separated in a double rectification column comprising a higher pressure rectification column, a lower pressure rectification column, and a first condenser-reboiler, of which the condensing passages communicate with an upper region of the higher pressure rectification column, and the reboiling passage communicate with a lower region of the lower pressure rectification column. A second condenser-reboiler is operated so as to reboil a liquid fraction obtained in the higher pressure rectification column. A stream of the air to be separated is partially or totally condensed by indirect heat exchange with a stream of nitrogen condensed in the first condenser-reboiler. At least part of the stream of condensed nitrogen is taken as product downstream of its heat exchange with the second stream of compressed air.
Claims19
A method of separating air comprising:
- introducing the air into a double rectification column comprising a higher pressure rectification column, a lower pressure rectification column, and a first condenser-reboiler, of which the condensing passages communicate with an upper region of the higher pressure rectification column so as to condense nitrogen, and the reboiling passages communicate with a lower region of the lower pressure rectification column;
- operating a second condenser-reboiler so as to reboil a liquid fraction obtained in the higher pressure rectification column, the second condenser-reboiler being heated either by means of a first stream of compressed air to be separated, the first stream of air thereby being partially or totally condensed, or by a flow of nitrogen-rich vapour formed by pre-separating the first stream of air in a further rectification column operating at a higher pressure than any obtaining in the higher pressure rectification column, the nitrogen-rich vapour thereby being partially or totally condensed;
- partially or totally condensing a second stream of compressed air to be separated by indirect heat exchange with a stream of the condensed nitrogen;
- and
- taking at least part of the stream of condensed nitrogen as product downstream of its heat exchange with the second stream of compressed air.
An apparatus for separating air, comprising:
- a double rectification column comprising a higher pressure rectification column, a lower pressure rectification column, and a first condenser-reboiler, of which the condensing passages communicate with an upper region of the higher pressure rectification column so as to condense nitrogen, and the reboiling passages communicate with a lower region of the lower pressure rectification column;
- a second condenser-reboiler, of which the reboiling passages communicate with a lower region of the higher pressure rectification column and the condensing passages communicate either directly with the source of the first stream of compressed air to be separated or with a nitrogen-rich vapour region of a further rectification column which in turn communicates with the said source;
- a first further condenser for partially or totally condensing, by indirect heat exchange with a stream of the condensed nitrogen, a second stream of compressed air to be separated;
- and
- means for taking as product at least part of the stream of condensed nitrogen downstream of its heat exchange with its second stream of compressed air.
Dependencies are inferred from the claim text.