SYSTEM FOR PROCESSING MERCURY IN EXHAUST GAS

摘要

Disclosed is an Hg removal system which removes Hg that is contained in an exhaust gas (12) from a boiler (11). The Hg removal system comprises: an ammonium chloride solution supply means (a reduction/oxidation assistant supply means) (16) that sprays an NH4Cl solution (14), which contains ammonium chloride as a reduction/oxidation assistant, into a gas duct (13) that is in the downstream of the boiler (11); a reduction denitration device (a reduction denitration means) (17) that comprises a denitration catalyst which reduces NOx in the exhaust gas (12) with an NH3 gas, while oxidizing mercury metal (Hg0) in the coexistence of an HCl gas; a heat exchanger (18) that performs heat exchange of the denitrated exhaust gas (12); a dust collector (19) that removes soot and dust in the denitrated exhaust gas (12); a wet desulfurization device (21) that removes divalent Hg2+, which is oxidized in the reduction denitration device (17), using a lime gypsum slurry (an alkali absorbing solution) (20); and a removal assistant supply means (23) that supplies a removal assistant (22) for removing impurities into the lime gypsum slurry (20) that circulates through the wet desulfurization device (21).