Methane/nitrogen separation process
AssigneeMembrane Technology and Research, Inc.
InventorsRichard W. Baker, Kaaeid A. Lokhandwala, Ingo Pinnau, Scott Segelke
Life of this patent
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Abstract
A membrane separation process for treating a gas stream containing methane and nitrogen, for example, natural gas. The separation process works by preferentially permeating methane and rejecting nitrogen. We have found that the process is able to meet natural gas pipeline specifications for nitrogen, with acceptably small methane loss, so long as the membrane can exhibit a methane/nitrogen selectivity of about 4, 5 or more. This selectivity can be achieved with some rubbery and super-glassy membranes at low temperatures. The process can also be used for separating ethylene from nitrogen.
Claims41
A process for treating a gas stream comprising methane and nitrogen, said process comprising the following steps:
- (a) providing a membrane having a feed side and a permeate side and being selective for methane over nitrogen;
- (b) passing said gas stream across the feed side of said membrane at a temperature at which the membrane exhibits a selectivity for methane over nitrogen of at least about 5;
- (c) withdrawing from said feed side a residue stream depleted in methane and enriched in nitrogen compared with said gas stream;
- (d) withdrawing from said permeate side a permeate stream enriched in methane and depleted in nitrogen compared with said gas stream.
A process for treating a gas stream comprising methane and nitrogen, said process comprising the following steps:
- (a) providing a first membrane having a first feed side and a first permeate side and being selective for methane over nitrogen;
- (b) passing said gas stream across said first feed side at a temperature at which said first membrane exhibits a selectivity for methane over nitrogen of at least about 5;
- (c) withdrawing from said first feed side a first residue stream depleted in methane and enriched in nitrogen compared with said gas stream;
- (d) withdrawing from said first permeate side a first permeate stream enriched in methane and depleted in nitrogen compared with said gas stream;
- (e) providing a second membrane having a second feed side and a second permeate side and being selective for methane over nitrogen;
- (f) passing said first permeate stream across said second feed side;
- (g) withdrawing from said second feed side a second residue stream depleted in methane and enriched in nitrogen compared with said first permeate stream;
- (h) withdrawing from said second permeate side a second permeate stream enriched in methane and depleted in nitrogen compared with said first permeate stream.
Dependencies are inferred from the claim text.