Method of recovering oxygen, nitrogen and air exhausted from air separator

Abstract

The present invention is method of recovering oxygen and nitrogen during air separation. One system is constituted with the spare expander of air separator, one increased heat exchanger, some pipes and valves. Air pumped by the main heat exchanger in the air separator, exhausted and pressureized air after compression, purification and cooling or exhausted and pressurized nitrogen after cooling inthe heat exchanger is expanded in the space expander and used as cooling work medium, and liquefied in the heat exchanger into liquid oxygen or liquid nitrogen, and the liquid oxygen or liquid nitrogen is collected in the liquid oxygen or liquid nitrogen storage. Meanwhile, the temperature of the exhausted air from the expander may be controlled to liquefy partially the exhausted air or nitrogen.

Description

technical field [0001] The invention relates to a method for recovering emptied oxygen, nitrogen, and air during air separation, in particular to a method for liquefying and recovering emptied oxygen, nitrogen, and air during air separation to prepare oxygen and / or nitrogen. Background technique [0002] The existing air separation (separation by low temperature liquefaction and rectification) process is generally as follows: the air enters the main heat exchanger after being compressed and purified (dust removal, compression, air cooling to remove water, and molecular sieve adsorption to remove water and carbon dioxide). After the heater is cooled, it enters the rectification tower, where the air is separated to separate nitrogen and / or oxygen, and the nitrogen and / or oxygen separated from the rectification tower are exchanged by the main heat exchanger to obtain atmospheric nitrogen And / or oxygen, the nitrogen and / or oxygen through the main heat exchanger are generally pre...

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Problems solved by technology

On the other hand, the design capacity of the compressor in the general air separation unit is slightly higher than the processing capacity of the rectification unit, so that a part of the air will be vented before entering the molecular sieve adsorber for dehydration and carbon dioxide; / or oxygen is also often greater than the demand of the production device, and there will also be a part of nitrogen and / or oxygen or vent or recover after going out of the main heat exchanger and being compressed. The recovery of vented oxygen and / or nitrogen in the prior art generally adopts Add a new set of gas liquefaction equipment, a large investment

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