Union Carbide Corporation

Robert T Cassidy

Robert G Werner

Willis E Hiscock

Kishore J Doshi

Thomas J Dangieri

In air separation and other gas separations employing pressure swing adsorption technology, reduced cycle times are achieved by an advantageous combination of simultaneous processing steps. The repressurization step in which the upper adsorption pressure is reached in each adsorbent bed is carried out while simultaneously withdrawing product gas from that bed. Following cocurrent depressurization steps in which released void space gas is used for pressure equalization and provide purge gas purposes, each bed, in turn, is further cocurrently depressurized, and the released gas is used for pressure equalization purposes, while the bed is simultaneously being countercurrently depressurized. This latter countercurrent depressurization is then continued to a lower desorption pressure is reached, after which the bed is partially repressurized by pressure equalization, before being further repressurized to upper adsorption pressure with simultaneous withdrawal of product as the next processing cycle is begun.

Pressure swing adsorption process

In air separation and other gas separations employing pressure swing adsorption technology, reduced cycle times are achieved by an advantageous combination of simultaneous processing steps. The gas released upon cocurrent depressurization from higher adsorption pressure is employed simultaneously for pressure equalization and provide purge purposes. Cocurrent depressurization is also carried out at an intermediate pressure level, while countercurrent depressurization is simultaneously carried out at the opposite end of the bed being depressurized to its lower desorption pressure level.

A portion of the void space gas released from an adsorbent bed during the cocurrent depressurization thereof, and to be used to provide purge gas, is passed directly to a bed to be purged. The remaining portion of such gas is passed simultaneously to an external surge drum. The gas in the external drum is thereafter passed to a bed to be purged.

Product recovery in pressure swing adsorption process and system

A rapid pressure swing adsorption process utilizes two or more adsorbent beds, each of which undergoes on a cyclic basis, high pressure feed-adsorption, countercurrent exhaust and repressurization. The feeding of the feed gas mixture, such as air, to the adsorption system is temporarily discontinued upon completion of the feed step to each bed, with the discontinuity of feed before commencing the passing of said feed gas mixture to the next succeeding bed being essentially the same throughout the processing cycle, with the feed step at adsorption pressure for each bed being essentially the same and with said feed step being shorter in duration than said exhaust step.

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Waldwick, NJ, United States of America

Robert T Cassidy