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US 4,781,907 AGranted
Production of membrane-derived nitrogen from combustion gases
OwnerJohn M. McNeillinventor
Life of this patent
Estimating the term…
Abstract
High-purity nitrogen is recovered from combustion gas such as exhaust stack gases, by utilizing selective gas-permeable membranes to separate by rejection, nitrogen from the other gases present in the gas stream.
Claims12
A process for the production of nitrogen, which comprises:
- (a) combusting a carbonaceous fuel to form a combustion gas comprising nitrogen, carbon dioxide, and oxygen;
- (b) treating the combustion gas to remove to the extent present particulates, the oxides of sulfur, and the oxides of nitrogen and compressing the treated gas stream with or without water condensation in one or more stages of compression to a pressure sufficient to enable membrane separation of molecular nitrogen from carbon dioxide and oxygen;
- and
- (c) contacting the compressed, treated gas stream at a temperature of from about 70.degree. to about 160.degree. F. with at least one membrane preferentially selective to reject nitrogen to yield a permeate comprising carbon dioxide and oxygen and a residue concentrated in nitrogen, said membrane having an oxygen and/or carbon dioxide-to-nitrogen ratio of permeability of from about 2.0 to about 20.0 and there is formed a nitrogen enriched gas stream containing at least 90% by volume nitrogen and no more than about 1 to about 5% by volume oxygen.
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A membrane-permeation process for producing nitrogen-enriched gas which comprises:
- (a) combusting a carbonaceous fuel to form a combustion gas comprising, on a dry basis, from about 70 to about 86% by volume nitrogen, from about 4 to about 20% by volume carbon dioxide and from about 0.1 to about 6% by volume oxygen;
- (b) processing the combustion gas stream in a first stage to remove to the extent present;
- (i) particulate matter by filtration;
- and
- (ii) gas oxides of nitrogen and oxides of sulfur;
- (c) compressing the treated combustion as to a pressure of about 100 to about 800 psig;
- (d) introducing the compressed combustion gas stream to a membrane separation zone comprising at least one membrane having an oxygen and/or carbon dioxide-to-nitrogen ratio of permeability of from about 2.0 to about nitrogen ratio of permeability of from about 2.0 to about 20.0 which rejects nitrogen gas to form a nitrogen-enriched gas stream to the preferential passage of oxygen and at a temperature of from about 70.degree. to about 160.degree. F. and above the dew point of water in the compressed combustion gas stream, said nitrogen enriched gas stream containing at least 90% by volume nitrogen and no more than about 1 to about 5% by volume oxygen;
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- (e) collecting the nitrogen-enriched gas stream as a residue of membrane separation.
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Dependencies are inferred from the claim text.