Method of producing nitrogen enriched air
First Claim
1. In a gas separation membrane method of enriching the concentration of nitrogen of ambient air utilizing a membrane module having an elongated shell defining a longitudinal axis, a plurality of membranes each comprising a microporous hollow fiber defining an outer surface and a lumen surface and having a nonporous layer selectively permeable to oxygen and nitrogen deposited on at least one of the outer surface and the lumen surface, the membranes being positioned within the elongated shell to form an elongated fiber bundle having terminal potted ends to join the fibers in parallel fluid communication defining a tube side volume within the lumen surfaces and defining a shell side volume outside the nonporous layer and within the shell between the potted ends, in which a feed gas of composition of ambient air is continuously introduced into one of either the tube side volume or the shell side volume thereby causing a permeate gas flow through the membranes to a permeate volume and leaving a retentate gas of composition enriched in nitrogen relative to concentration of nitrogen of the feed gas, the improvement comprises introducing into the one of either the tube side volume or shell side volume the feed gas free of any recycled gas and feeding a sweep flow of the feed gas into the permeate volume at a rate effective to produce in a single stage separation, retentate gas having a concentration of nitrogen in the range of 80-90 vol. %.
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Accused Products
Abstract
A membrane separation process and apparatus for carrying out the process involves contacting a gas feed mixture with one side of a selectively gas permeable membrane and allowing the components to pass through the membrane to form a permeate composition in contact with the opposite side of the membrane and leave a retentate composition on the feed side of the membrane. The process includes introducing a sweep flow of feed gas into the permeate composition near the membrane at a rate effective to increase the enrichment of the retentate composition in the less preferentially permeable component of the feed mixture to a concentration much greater than is achieved without the sweep flow. This process is especially well suited to improve single stage membrane separation effectiveness so that the need for conventional multistage separations to achieve moderate to high purity retentate compositions can be obviated. The novel process is particularly useful for providing enriched air in the concentration range of 80-90 vol. % nitrogen.
103 Citations
17 Claims
- 1. In a gas separation membrane method of enriching the concentration of nitrogen of ambient air utilizing a membrane module having an elongated shell defining a longitudinal axis, a plurality of membranes each comprising a microporous hollow fiber defining an outer surface and a lumen surface and having a nonporous layer selectively permeable to oxygen and nitrogen deposited on at least one of the outer surface and the lumen surface, the membranes being positioned within the elongated shell to form an elongated fiber bundle having terminal potted ends to join the fibers in parallel fluid communication defining a tube side volume within the lumen surfaces and defining a shell side volume outside the nonporous layer and within the shell between the potted ends, in which a feed gas of composition of ambient air is continuously introduced into one of either the tube side volume or the shell side volume thereby causing a permeate gas flow through the membranes to a permeate volume and leaving a retentate gas of composition enriched in nitrogen relative to concentration of nitrogen of the feed gas, the improvement comprises introducing into the one of either the tube side volume or shell side volume the feed gas free of any recycled gas and feeding a sweep flow of the feed gas into the permeate volume at a rate effective to produce in a single stage separation, retentate gas having a concentration of nitrogen in the range of 80-90 vol. %.
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8. A method of increasing the concentration of nitrogen in air comprising
providing a membrane module having an elongated shell defining a longitudinal axis, a plurality of membranes selectively gas permeable for oxygen and nitrogen positioned within the elongated shell, the membranes comprising (i) a microporous hollow fiber having a pore size of about 0.005-1.0 μ - m, (ii) an outer surface, (iii) a lumen defining a lumen surface, and (iv) a nonporous layer of a selectively gas permeable polymer less preferentially permeable for nitrogen than for oxygen deposited onto at least one of the outer surface and the lumen surface, in which the hollow fibers are positioned to form an elongated fiber bundle having terminal potted ends which connect the lumina in parallel fluid communication to define a tube side zone within the lumina and a shell side zone outside the nonporous layer and within the shell between the potted ends,
a plurality of shell side ports operative to conduct gas to or from the shell side zone, a tube side inlet port operative to introduce gas into one end of the tube side zone, and a tube side outlet port operative to withdraw gas from the other end of the tube side zone, supplying a feed of air having a composition of about 79 vol. % nitrogen and about 21 vol. % oxygen to a first shell side port, contacting one side of the membranes with the feed of air, thereby causing oxygen and nitrogen to permeate the membranes to produce a retentate gas mixture in contact with the one side of the membranes having a first concentration of nitrogen, and a permeate gas mixture in contact with the opposite side of the membranes, introducing through the tube side inlet port and into the permeate gas mixture a sweep flow of the feed of air at a rate effective to produce a second concentration of nitrogen of about 80-90 vol. % in the retentate gas mixture and higher than the first concentration, withdrawing the retentate gas mixture from a second shell side port, and withdrawing the permeate gas mixture from the tube side outlet port, in which said second concentration is produced in a single stage membrane separation. - View Dependent Claims (9, 10, 11, 12)
- m, (ii) an outer surface, (iii) a lumen defining a lumen surface, and (iv) a nonporous layer of a selectively gas permeable polymer less preferentially permeable for nitrogen than for oxygen deposited onto at least one of the outer surface and the lumen surface, in which the hollow fibers are positioned to form an elongated fiber bundle having terminal potted ends which connect the lumina in parallel fluid communication to define a tube side zone within the lumina and a shell side zone outside the nonporous layer and within the shell between the potted ends,
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13. A method of increasing the concentration of nitrogen in air comprising
providing a membrane module having an elongated shell defining a longitudinal axis, a plurality of membranes selectively gas permeable for oxygen and nitrogen positioned within the elongated shell, the membranes comprising (i) a microporous hollow fiber having a pore size of about 0.005-1.0 μ - m, (ii) an outer surface, (iii) a lumen defining a lumen surface, and (iv) a nonporous layer of a selectively gas permeable polymer less preferentially permeable for nitrogen than for oxygen deposited onto at least one of the outer surface and the lumen surface, in which the hollow fibers are positioned to form an elongated fiber bundle having terminal potted ends which connect the lumina in parallel fluid communication to define a tube side zone within the lumina and a shell side zone outside the nonporous layer and within the shell between the potted ends,
a plurality of shell side ports operative to conduct gas to or from the shell side zone, a tube side inlet port operative to introduce gas into one end of the tube side zone, and a tube side outlet port operative to withdraw gas from the other end of the tube side zone, supplying a feed of air having a composition of about 79 vol. % nitrogen and about 21 vol. % oxygen to the tube side inlet port, contacting one side of the membranes with the feed of air, thereby causing oxygen and nitrogen to permeate the membranes to produce a retentate gas mixture in contact with the one side of the membranes having a first concentration of nitrogen, and a permeate gas mixture in contact with the opposite side of the membranes, introducing through a first shell side port and into the permeate gas mixture a sweep flow of the feed of air at a rate effective to produce a second concentration of nitrogen of about 80-90 vol. % in the retentate gas mixture and higher than the first concentration, withdrawing the retentate gas mixture from the tube side outlet, and withdrawing the permeate gas mixture from a second shell side port, in which said second concentration is produced in a single stage membrane separation. - View Dependent Claims (14, 15, 16, 17)
- m, (ii) an outer surface, (iii) a lumen defining a lumen surface, and (iv) a nonporous layer of a selectively gas permeable polymer less preferentially permeable for nitrogen than for oxygen deposited onto at least one of the outer surface and the lumen surface, in which the hollow fibers are positioned to form an elongated fiber bundle having terminal potted ends which connect the lumina in parallel fluid communication to define a tube side zone within the lumina and a shell side zone outside the nonporous layer and within the shell between the potted ends,
Specification
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- Resources
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Current AssigneeCms Technologies Holdings, Inc.
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Original AssigneeCms Technologies Holdings, Inc.
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InventorsNemser, Stuart Marshall, Callaghan, Kevin Patrick
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Primary Examiner(s)Spitzer, Robert H.
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Application NumberUS09/506,636Time in Patent Office998 DaysField of Search95/45--56, 96/4, 96/8, 96/10, 96/12--14US Class Current95/54CPC Class CodesB01D 53/22 by diffusion manufacturing ...
