Union Carbide Corporation

Uop Lcc

Robert G Werner

Robert T Cassidy

Willis E Hiscock

Kishore J Doshi

Michael J Mitariten

Homer Fay

A gas separation process and system for integrating a gas permeable membrane system with a multiple bed pressure swing adsorption system to produce a mixed gas product having a preset adjustably controlled gas ratio and a high purity second gas component. The permeate stream from the gas permeable membrane system is fed to the PSA unit and the tail gas from the PSA unit is compressed and blended with the non-permeate stream to form the mixed gas product. The pressure of the permeate stream is controlled to adjustably control the gas ratio of the mixed gas product.

Integrated membrane/PSA process and system

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

A feed gas is passed to a pressure swing adsorption system, each bed of which undergoes a processing cycle that includes (1) pressurization (2) copurge at upper adsorption pressure, (3) countercurrent depressurization, including, in some embodiments, evacuation to a lower subatmospheric desorption pressure. By recycling effluent gas released upon copurge and countercurrent depressurization for use in the pressurization or the copurge step, the more readily adsorbable component of the feed gas is advantageously recovered at high purity and at high recovery levels. Enriched less readily adsorbable component is also recoverable as coproduct effluent at relatively high recovery levels. The process can be advantageously employed for the separation and recovery of product nitrogen from air.

Enhanced pressure swing adsorption processing

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 method for the removal of polymer from a straight-chain paraffin purge medium used in a monoolefin adsorption-desorption separation process comprising recycling a countercurrent purge step polymer containing straight-chain paraffin product for use as purge medium in the process without separation of polymer from the straight-chain paraffin and separating polymer from at least a portion of an adsorption step and a copurge step polymer containing straight-chain paraffin product and recycling the purified straight-chain paraffin for use as purge medium in the process.

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Danbury, CT, United States of America

Robert G Werner