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US 4,902,321 AGranted
Cryogenic rectification process for producing ultra high purity nitrogen
AssigneeUnion Carbide Corporation
InventorHarry Cheung
Life of this patent
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Abstract
A process for producing ultra high purity nitrogen from nitrogen produced by the cryogenic rectification of air wherein superatomospheric nitrogen is progressively condensed and revaporized to effect rejection of lower boiling impurities without need for additional energy beyond that contained in the nitrogen input.
Claims11
Process for producing ultra high purity nitrogen comprising.
- (a) introducing compressed feed air into a cryogenic rectification zone;
- (b) separating the compressed feed air by cryogenic rectification to produce higher pressure nitrogen-rich vapor containing lower boiling impurities;
- (c) partially condensing nitrogen-rich vapor to produce nitrogen-richer liquid and vapor enriched with lower boiling impurities;
- (d) expanding the nitrogen-richer liquid to produce lower pressure nitrogen-richer fluid;
- (e) passing the resulting lower pressure nitrogen-richer fluid in indirect heat exchange with the nitrogen-rich vapor to carry out the partial condensation of step (c) and to produce nitrogen-richer vapor;
- and
- (f) recovering nitrogen-richer vapor a ultra high purity nitrogen product.
4 more elements
Dependencies are inferred from the claim text.