EXHAUST GAS TREATMENT SYSTEM AND ITS METHOD OF COAL FIRED BOILER

摘要

PPROBLEM TO BE SOLVED: To provide an exhaust gas treatment system and its method of a coal fired boiler efficiently removing mercury in the exhaust gas from the coal fired boiler. PSOLUTION: The exhaust gas treatment system is provided with: a denitration device 13 removing nitrogen oxides in the exhaust gas from the coal fired boiler 11; an air preheater 14 recovering heat in the gas; a dust collector 15 removing soot and dust in the gas; a gas-liquid contact type desulfurizer 16 removing sulfur oxides in the gas by a lime-gypsum method and mercury oxide; and a chimney 17 discharging gas after desulfurization to the outside. The system comprises a solid-liquid separator 22 drawing out slurry 21 containing lime-gypsum from the desulfurizer 16 to the outside for solid-liquid separation. Water 23 is removed in the solid-liquid separator 22, condensed slurry 24 is returned to a lower part of the desulfurizer 16, and the gypsum concentration in the slurry 25 in the desulfurizer 16 is kept at 10% or more. PCOPYRIGHT: (C)2009,JPO&INPIT