Purifying flue gas comprises contacting gas rich in carbon dioxide and containing sulfur dioxide, nitrogen oxides and oxygen with acid, separating sulfuric acid and concentrating gas into sulfur dioxide, nitric oxide and nitrogen dioxide

摘要

Purifying flue gas (5) rich in carbon dioxide and containing sulfur dioxide (SO 2) and/or nitrogen oxide (NOx) and oxygen comprises: contacting the gas rich in carbon dioxide and containing SO 2, NOx and oxygen with an acid or its mixture; separating the sulfuric acid (15, 25, 35, 41) from gas rich in carbon dioxide; carrying out the contacting step in contactors (1, 2, 3, 4); concentrating the gas into SO 2by recycling a part of the flue gas rich in carbon dioxide; and/or (e) concentrating gas rich in carbon dioxide into nitric oxide and/or nitrogen dioxide. Purifying flue gas (5) rich in carbon dioxide and containing sulfur dioxide (SO 2) and/or nitrogen oxide (NOx) (as nitric oxide (NO) and/or nitrogen dioxide (NO 2)) and oxygen comprises: (a) contacting the gas rich in carbon dioxide and containing SO 2, NOx and oxygen with an acid or a mixture of acid for a duration to transform a part of the SO 2into sulfuric acid; (b) separating the sulfuric acid (15, 25, 35, 41) from gas rich in carbon dioxide to produce a gas depleted in SO 2; (c) carrying out the step in contactors (1, 2, 3, 4) to produce a carbon dioxide enriched gas and depleted in SO 2; (d) concentrating the gas rich in carbon dioxide into SO 2by recycling a part of the flue gas rich in carbon dioxide and/or a part of the gas enriched in carbon dioxide and depleted in SO 2in upstream of the combustion; and/or (e) concentrating gas rich in carbon dioxide into NO and/or NO 2by recycling a gas rich in NO 2derived from gas rich in carbon dioxide depleted in SO 2towards at least one of the contactors.