System and method for treating mercury in flue gas

1. A system for treating mercury in flue gas, comprising:

a boiler that discharges flue gas containing mercury;

a reduction-oxidation assistant supplying unit that is provided downstream of the boiler to supply a reduction-oxidation assistant;

a denitration device that is provided downstream of the reduction-oxidation assistant supplying to denitrate nitrogen oxide (NOx) in the flue gas;

an air heater that is provided downstream of the denitration device to adjust a temperature of the flue gas;

a heat exchanger that is provided downstream of the air heater to lower the temperature of the flue gas;

a mercury adsorbent supply device that is provided downstream of the heat exchanger and supplies a mercury adsorbent into the flue gas so as to adsorb the mercury with the mercury adsorbent;

a precipitator that is provided downstream of the heat exchanger to collect the mercury adsorbent with adsorbed mercury and soot in the flue gas;

a mercury adsorption assistant supply device that is provided downstream of the precipitator and supplies a mercury adsorption assistant into the flue gas so as to remove mercury remaining in the flue gas; and

a desulfurization device that is provided downstream of the mercury adsorption assistant supply device to remove sulfur oxide (SOx) in the flue gas.

2. A method for treating mercury in flue gas comprising:

discharging flue gas containing mercury;

supplying a reduction-oxidation assistant;

denitrating nitrogen oxide (NOx) in the flue gas;

adjusting a temperature of the flue gas;

lowering the temperature of the flue gas;

supplying a mercury adsorbent into the flue gas so as to adsorb the mercury with the mercury adsorbent;

collecting the mercury adsorbent with adsorbed mercury and soot in the flue gas;

supplying a mercury adsorption assistant into the flue gas so as to remove mercury remaining in the flue gas; and

removing sulfur oxide (SOx) in the flue gas.