| abstract |
A method of recovering carbon dioxide from a stream of CO 2 -containing flue gases, includes the steps of contacting the stream at a gas pressure above atmospheric pressure with an aqueous solvent system to effect absorption of CO 2 from the stream whereby the stream becomes a stream of CO 2 -leaner flue gases, and separating the solvent containing the absorbed CO 2 from the stream of CO 2 -leaner flue gases to form a CO 2 rich solvent stream. The stream of CO 2 -leaner flue gases is expanded in a manner whereby the CO 2 -leaner flue gases are cooled, and one or more process streams are cooled by heat exchange with the cooled flue gases. In one aspect, the aqueous solvent system contains dissolved ammonia, and ammonium, carbonate and bicarbonate ions, to effect absorption of CO 2 from the stream whereby the stream becomes a stream of CO 2 -leaner flue gases. In this case, the CO 2 -leaner flue gases are contacted with water that dissolves ammonia therefrom, which dissolved ammonia may be recycled back to the solvent system, and the CO 2 -leaner flue gases are thereafter contacted with a sub-stream of CO 2 -rich flue gases that contains sufficient sulphur and/or nitrogen oxides to react with a proportion of the ammonia in the CO 2 -leaner flue gases. The products of the reaction are recovered from the CO 2 -leaner flue gases. Apparatus for carrying out these methods are also disclosed. |