WET FLUE GAS DESULFURIZATION METHOD

摘要

PURPOSE:To nearly eliminate CaSO3 contained in circulated slurry liquid of an absorption tower and to enhance desulfurization by adding both a Ca absorbent and an alkali agent to slurry while maintaining pH at 4.5 or higher after absorption and oxidation incorporated in the absorption tower. CONSTITUTION:Flue gas 1 contg. SOX is fed to an absorption tower 2 to remove SOX and also air 6 for oxidation is fed to a circulation tank 5 of the absorption tower. Absorbent slurry 10 is fed to the bottom of the circulation tank 5 and NaOH is fed as an alkali agent 11 to the circulation tank 5 in order to hold pH of circulated slurry of the absorbent to >=5.0. Slurry after absorption and oxidation is drawn out from the circulation tank 5 and fed to a reaction tank 12 and sulfuric acid is added thereto and furthermore the mixture is fed to a pH regulation tank 14 and pH is regulated to 5.0 by an NaOH soln. 11 and thereafter fed to a thickener 15 and separated into gypsum 16 and mother liquid 19 and this mother liquid 19 is fed to an absorbent slurry tank 9 to mix with an absorbent 8.