Mercury reduction system and mercury reduction method of flue gas containing mercury

A mercury reduction method of flue gas containing mercury for reducing nitrogen oxide and mercury in flue gas discharged from a boiler, the mercury reduction method of flue gas containing mercury comprising:

• a step of liquid material spraying for spraying a liquid material obtained by dissolving an oxidation-reduction agent that reduces nitrogen oxide in the flue gas by a denitration catalyst and oxidizes mercury in a presence of hydrogen chloride with a solvent, into a flue of the boiler in a liquid state;
• a step of gaseous material spraying for spraying at least one of a reducing agent that reduces nitrogen oxide in the flue gas by the denitration catalyst and a mercury chlorinating agent that oxidizes mercury in the flue gas in the presence of the hydrogen chloride by the denitration catalyst or both of them into the flue as a gaseous material;
• a step of reduction denitration treating for reducing nitrogen oxide in the flue gas by the denitration catalyst with ammonia and oxidizing mercury in the presence of the hydrogen chloride;
• and
• a step of wet desulfurizing for reducing mercury oxidized at the step of reduction denitration treating by with an alkali absorbent.