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US 5,313,802 AGranted
Process to produce a krypton/xenon enriched stream directly from the main air distillation column
AssigneeAir Products and Chemicals, Inc.
InventorsRakesh Agrawal, Steven L. Feldman
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Abstract
A process is set forth for producing a krypton/xenon enriched stream directly from the main air distillation column in a cryogenic air separation process. A column bypass is suggested in the bottom few trays of the low pressure column in order to concentrate krypton and xenon in the sump while rejecting the majority of methane in the gaseous oxygen product.
Claims7
In a process for the cryogenic distillation of an air feed using a multiple column distillation system comprising a high pressure column and a low pressure column wherein:
- (a) at least a portion of the air feed is fed to the high pressure column in which the air feed is rectified into a high pressure nitrogen overhead and a high pressure crude liquid oxygen bottoms;
- (b) at least a portion of the high pressure crude liquid oxygen bottoms is fed to the low pressure column in which the high pressure crude liquid oxygen bottoms is rectified into a low pressure nitrogen overhead and a low pressure liquid oxygen bottoms;
- and
- (c) at least a portion of the low pressure liquid oxygen bottoms is boiled in a sump located in the bottom of the low pressure column;
- a method to produce a stream enriched in krypton and xenon directly from the low pressure column comprising:
- (i) withdrawing an oxygen-enriched vapor stream and an oxygen-enriched liquid stream from a withdrawal point located at least one equilibrium stage above the sump;
- (ii) returning the oxygen-enriched liquid stream to a return point located between the sump and the low pressure column's initial equilibrium stage;
- and
- (iii) withdrawing the krypton/xenon enriched stream from the bottom of the sump.
6 more elements
Dependencies are inferred from the claim text.