EXHAUST GAS TREATMENT APPARATUS, AND ORP CONTROL METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide an exhaust gas treatment apparatus by which mercury contained in exhaust gas from a boiler can be easily removed and to provide a method for controlling an OPR of the exhaust gas treatment apparatus.

SOLUTION: This exhaust gas treatment apparatus has: a redox agent supplying means for supplying a redox agent, which produces hydrogen chloride and ammonia when vaporized, to a discharge flue for the exhaust gas from a boiler; a reduction/denitration device that has a denitration catalyst for reducing the nitrogen oxide in the exhaust gas using ammonia and oxidizing the mercury in the coexistence of hydrogen chloride; a wet desulfurization device for absorbing and removing the sulfur oxide in the exhaust gas and the oxidized mercury in the reduction/denitration device using an absorbing solution; an oxidation reduction potential (ORP) meter for measuring the ORP of the absorbent; a solid-liquid separating means for separating the solids and the mercury from the liquids in the desulfurization waste water discharged from the wet desulfurization device; a separated-liquid return line for returning the separated liquids separated by the solid-liquid separating means to the wet desulfurization device; an oxidizer supplying means for supplying an oxidizer to the separated liquids that are returned to the wet desulfurization device; and a controlling means for adjusting the supply levels of the oxidizer to control the ORP of the absorbent.

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