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US 5,309,719 AGranted
Process to produce a krypton/xenon enriched stream from a cryogenic nitrogen generator
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 from a cryogenic nitrogen generator. Distillation of the oxygen product stream at the top of the low pressure column is suggested in order to concentrate krypton and xenon while rejecting the majority of methane in the oxygen product stream.
Claims4
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;
- (c) a first portion of the low pressure liquid oxygen bottoms is boiled in a first sump located in the bottom of the low pressure column;
- and
- (d) a second portion of the low pressure liquid oxygen bottoms is boiled in a second sump located above the low pressure column by indirect heat exchange against condensing low pressure nitrogen overhead;
- a method for producing a stream enriched in krypton and xenon comprising:
- (i) distilling the vapor generated from said boiling of the second portion of the low pressure liquid oxygen bottoms in step (d) in a third distillation column having the second sump located in its bottom wherein a third portion of the low pressure liquid oxygen bottoms is used to provide reflux for the third distillation column;
- and
- (ii) withdrawing the krypton/xenon enriched stream from the bottom of the second sump.
6 more elements
Dependencies are inferred from the claim text.