AIR POLLUTION CONTROL SYSTEM AND METHOD FOR COAL COMBUSTION BOILER

摘要

A discharge gas treatment system for coal-fired boilers which comprises: a denitration device (13) in which nitrogen oxides contained in a discharge gas discharged from a coal-fired boiler (11) are removed; an air preheater (14) which recovers heat from the gas; a dust collector (15) which removes soot/dust from the gas; a gas/liquid contact type desulfurizer (16) in which sulfur oxides contained in the gas are removed by the lime-gypsum method and, simultaneously therewith, mercury oxide is removed; and a chimney (17) through which the gas which has undergone desulfurization is discharged outside. The system further includes a solid/liquid separator (22) in which a slurry (21) which contains limestone-gypsum and has been discharged from the desulfurizer (16) is subjected to solid-liquid separation. The water (23) separated by the solid/liquid separator (22) is removed, and the concentrated slurry (24) is returned to a lower part of the desulfurizer (16) to thereby regulate a slurry (25) in the desulfurizer (16) so as to have a gypsum concentration of 10% or higher.