Patent ID: 8016923

Claim:
A combustion system adapted to control carbon dioxide emissions, comprising: (a) a combustion unit configured to combust a mixture of fuel and air, oxygen-enriched air, or oxygen, thereby producing an exhaust stream containing carbon dioxide; (b) a carbon dioxide capture unit configured to remove a portion of carbon dioxide in concentrated form from the exhaust stream, to create an off-gas stream from the capture unit that is less concentrated in carbon dioxide than the exhaust stream from the combustion unit; and (c) a sweep-based membrane separation unit, comprising (i) at least one membrane having a feed side and a permeate side, where the at least one membrane is selectively permeable to carbon dioxide over nitrogen and to carbon dioxide over oxygen, (ii) means for passing at least a portion of the off-gas stream generated from the carbon dioxide capture step across the feed side of the at least one membrane, (iii) means for passing air, oxygen-enriched air, or oxygen as a sweep stream across the permeate side of the at least one membrane, (iv) means for withdrawing from the feed side of the at least one membrane a carbon-dioxide depleted vent stream, and (vi) means for withdrawing from the permeate side of the at least one membrane a permeate stream comprising oxygen and carbon dioxide, and to pass the permeate stream to the combustion unit as at least part of the air, oxygen-enriched air, or oxygen to the combustion unit.