Air separation process for the production of oxygen-rich and nitrogen-rich products
AssigneeAir Products and Chemicals, Inc.
InventorsDonald W. Woodward, Rakesh Agrawal
Life of this patent
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Abstract
The present invention is an improvement to a two distillation column, cryogenic air separation process which produces nitrogen-rich and oxygen-rich products. The improvement to the process is condensing at least a portion of the nitrogen overhead from the high pressure column in a reboiler/condenser against a crude liquid oxygen stream and in an intermediate reboiler/condenser located in the low pressure column against internal low pressure column streams. The condensed nitrogen overhead is fed either to the low pressure or high pressure columns as reflux. The vaporized portion of the crude liquid oxygen stream is work expanded to provide some or all of the refrigeration required for the process.
Claims5
In a process for the production of low purity gaseous oxygen by the cryogenic distillation of air using two integrally communicating distillation columns at different pressures having a high pressure distillation column and a low pressure distillation column, wherein feed air is compressed, purified of comtaminants which will freeze at cryogenic temperatures, and cooled., wherein at least a major portion of the compressed, cooled, purified feed air is fed to the high pressure distillation column., wherein a liquid oxygen stream is produced at the bottom of the low pressure distillation column., and wherein, at least a portion of the liquid oxygen stream from the low pressure distillation column is vaporized by heat exchange with at least a portion of the feed air;
- the improvement for increasing process energy efficiency comprises providing reflux for both the high pressure and low pressure columns by condensing at least a portion of nitrogen overhead produced at the top of the high pressure column, wherein a first portion of the high pressure column nitrogen overhead is condensed in a reboiler/condenser by heat exchange with a crude liquid oxygen stream, which as a result of the heat exchange is partially vaporized at a pressure greater than the low pressure column pressure and the vaporized portion is removed from the reboiler/condenser as a crude oxygen vapor stream, and wherein a second portion is condensed in an intermediate reboiler/condenser located internal to the low pressure column, and providing further refrigeration to the process by work expanding at least a portion of the crude oxygen vapor stream.
Dependencies are inferred from the claim text.