Process and system for the production of dry, high purity nitrogen
AssigneeUnion Carbide Corporation
InventorRavi Prasad
Life of this patent
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Abstract
High purity nitrogen from an air separation membrane/deoxo system is dried in a membrane dryer unit preferably operated with a countercurrent flow path in the membrane bundle. Drying is enhanced by the use of purge gas on the permeate side of the membrane dryer unit, with feed air, product nitrogen or waste gas from the air separation membrane system being used as purge gas.
Claims23
An improved process for the production of dry, high purity nitrogen from air in which an air separation membrane system is used to produce purified nitrogen from feed air for passage to a catalytic combustion system for reaction of residual oxygen with hydrogen, the residual wet, high purity nitrogen stream being cooled and passed to condensate removal means prior to drying, the improvement comprising:
- (a) passing said wet, high purity nitrogen stream from an air separation membrane system in which it is produced from feed air to a membrane dryer unit capable of selectively permeating water present therein;
- (b) recovering dry, high purity nitrogen product gas from the membrane dryer unit as non-permeate gas;
- (c) withdrawing water vapor as the permeate gas from the low pressure permeate side of the membrane dryer unit;
- (d) passing a relatively dry purge gas to the low pressure permeate side of the membrane dryer unit to facilitate the carrying away of water vapor from the surface of the membrane and maintaining the driving force for removal of water vapor through the membrane from the high purity nitrogen stream for enhanced moisture separation therefrom, said relatively dry purge gas comprising waste gas from said air separation membrane system, feed air of nitrogen product gas, whereby the passage of purge gas on the permeate side of the membrane dryer unit enables the desired moisture removal to be achieved with minimum loss of desired nitrogen product gas.
An improved system for the production of dry, high purity nitrogen from air in which an air separation membrane system produces purified nitrogen from feed air, a catalytic combustion system is adapted to react hydrogen with residual oxygen present in said purified nitrogen to produce a wet, high purity nitrogen stream, and cooling and condensate removal means are incorporated for the processing of said nitrogen stream prior to drying, the improvement comprising:
- (a) a membrane dryer unit capable of selectively permeating residual water present in the wet, high purity nitrogen stream;
- (b) conduit means for passing said wet, high purity nitrogen feed gas to said membrane dryer unit;
- (c) conduit means for recovering dry, high purity nitrogen product gas as non-permeate gas from the membrane dryer unit;
- (d) conduit means for passing a relatively dry purge gas to the low pressure permeate side of the membrane dryer unit to facilitate the carrying away of water vapor from the surface of the membrane and maintaining the driving force for removal of water vapor through the membrane from the high purity nitrogen stream for enhanced moisture separation therefrom, said relatively dry purge gas comprisinq waste gas from said air separation membrane system, feed air or nitrogen product gas, whereby the provision for purge gas on the permeate side of the membrane dryer unit facilitates the desired moisture removal to be achieved with minimum loss of nitrogen product gas.
Dependencies are inferred from the claim text.