SEPARATION OF MIXTURE BY PRESSURE VARIATION TYPE ADSORPTION

摘要

A gas mixture, typically air, is separated by pressure swing adsorption. Compressed air is passed into a bed 12 of carbon molecular sieve. Nitrogen is the least readily adsorbed component of the mixture and a gas mixture enriched in nitrogen flows out of the bed 12 into a reservoir 28. At the end of the adsorption step communication between the bed 12 and air compressor 4 is ended and the bed 12 is placed in communication with bed 14 (at atmospheric pressure) to equalise the pressure therebetween. The bed 12 is then regenerated by placing it in communication with the atmosphere via conduit 34 while the bed 14 is placed in communication with the compressor 4 and nitrogen-enriched gas mixture continues to be produced. The pressure between the beds 12 and 14 is then equalised. During this cycle according to the invention there is a bleed of nitrogen-enriched gas mixture back into the beds 12 and 14 from reservoir 28 via conduit 42 and pipe 44 whenever the pressure in at least one of the beds 12 and 14 is less than the pressure in the reservoir 28.