Selective-permeation gas-separation process and apparatus

A process for separating a permeant gas from a feed-gas mixture, the feed-gas mixture comprising the permeant gas and at least one other gaseous component, the process comprising the steps of:

• (a) introducing a selective-permeation liquid into a permeation-transfer chamber, the selective-permeation liquid being selectively permeable to the permeant gas relative to the other component of the feed-gas mixture, a first multiplicity of porous-wall hollow fibers extending through the permeation-transfer chamber to define gas-depletion hollow fibers, a second multiplicity of porous-wall hollow fibers extending through the permeation-transfer chamber to define gas-enrichement hollow fibers, the gas-depletion and the gas-enrichment hollow fibers commingling in close proximity to one another in the permeation-transfer chamber, the gas-enrichment hollow fibers and the gas-depletion hollow fibers together defining gas-transfer hollow fibers, radially-outer surfaces of the walls of the permeant-gas-transfer hollow fibers being contacted by the selective-permeation liquid in the permeation-transfer chamber, surfaces of the walls of the gas-transfer hollow fibers in the permeation-transfer chamber being composed of a material which tends not to be wetted by the selective-permeation liquid;
• (b) introducing a stream of the feed-gas mixture into the lumina of the gas-depletion hollow fibers and allowing the feed-gas mixture to flow through the lumina in the permeation-transfer chamber so that the permeant gas in the feed gas mixture can pass through the pores of the walls of the gas-depletion hollow fibers into the selective permeation liquid in the permeation-transfer chamber and from the selective-permeation liquid through the pores of the walls of the gas-enrichment hollow fibers into the lumina of the fibers;
• (c) withdrawing permeant gas from the lumina of the gas-enrichment hollow fibers;
• and
• (d) withdrawing a stream of gas depleted in the permeant gas from the lumina of the gas-depletion hollow fibers.

A gas-transfer unit for selectively transferring a permeant gas from a feed-gas mixture comprising the permeant gas and at least one other component to an output fluid, the gas-transfer unit comprising:

• (a) a fluid-tight housing, an interior of the housing defining a gas-transfer chamber, the housing having a feed-gas input port, a depleted-gas output port, a sweep-fluid input port, an enriched-gas output port and a selective-permeation liquid inlet port, the five ports providing communication with the gas-transfer chamber;
• (b) gas-depletion porous-wall means located within the gas-transfer chamber for forming at least a portion of a wall of a gas-depletion channel which passes through the gas-transfer chamber, the gas-depletion channel connecting the feed-gas input port to the depleted-gas output port;
• (c) gas-enrichment porous-wall means located within the gas-transfer chamber for forming at least a portion of a wall of a gas-enrichment channel which passes through the gas-transfer chamber, the gas-enrichment channel connecting the sweep-fluid input port to the enriched-gas output port, the gas-enrichment channel being disjoint from the gas-depletion channel, a region within the gas-transfer chamber and outside of the gas-enrichment channel and the gas-depletion channel defining a selective-permeation chamber, the selective-permeation-liquid inlet port providing communication with the selective-permeation chamber, the selective-permeation chamber including open passages adjacent to the gas-depletion porous-wall means and the gas-enrichment porous-wall means to permit a substantially free liquid passage of a preselected selective-permeation liquid introduced into the selective-permeation chamber through the selective-permeation-liquid inlet port to contact the gas-depletion porous-wall means and the gas-enrichment porous-wall means, the gas-depletion porous-wall means and the gas-enrichment porous-wall means being made of a material which tends to prevent the selective-permeation liquid in the selective-permeation chamber from flowing into the gas-depletion channel and into the gas-enrichment channel, so that a selective-permeation liquid can be confined in the selective-permeation chamber to facilitate the selective transfer of the permeant gas from the gas-depletion channel to the gas-enrichment channel of the gas-transfer unit.