Method for the removal of carbon dioxide and sulfor oxides from combustion exhaust gas.

摘要

This invention relates to a method for the removal of sulfur oxides and carbon dioxide contained in combustion exhaust gas. More particularly, this invention provides a method for the removal of CO2 and SOx contained in combustion exhaust gas which comprises a high-performance desulfurization step for desulfurizing SOx-containing combustion exhaust gas until the SOx concentration in the desulfurized gas comes within the range of 5 to 10 ppm, and a decarbonation step for bringing the desulfurized gas into contact with an aqueous solution of an alcoholic hydroxyl-containing hindered amine to remove not only CO2 but also SOx so that the SOx concentration in the decarbonated gas is reduced to 1 ppm or less. In one preferred embodiment, the high-performance desulfurization step employed in the above-described method is a flue gas desulfurization step based on the wet lime-gypsum process using first and second absorption towers in which the combustion exhaust gas is brought into contact with a gypsum slurry containing 1% or less of calcium carbonate in the first absorption tower and then brought into contact with a gypsum slurry containing 1% or more of calcium carbonate in the second absorption tower.