Air pollutant control system and method for removing mercury in flue gas

An air pollutant control system comprising:

• a spray device that sprays hydrogen chloride into flue gas discharged from a coal combustion boiler;
• a denitration apparatus that reduces nitrogen oxide in flue gas into which the hydrogen chloride has been sprayed, and that oxidizes mercury;
• an air heater that recovers heat in gas from which the nitrogen oxide has been reduced;
• a dust collector that reduces dust in gas from which the heat has been collected;
• a desulfurization apparatus that absorbs sulfur oxide in gas from which the dust has been reduced;
• a stack from which gas thus desulfurized is discharged outside;
• a hydrogen chloride vaporizer that produces hydrogen chloride with a supply of concentrated hydrochloric acid;
• and
• a hydrochloric acid neutralization tank where at least one of dilute hydrochloric acid discharged from the hydrogen chloride vaporizer and the concentrated hydrochloric acid is neutralized with an alkali agent, wherein
• neutralized chloride is supplied to a coal feeder, mixed with coal, and then burned in the coal combustion boiler, so as to produce hydrogen chloride in flue gas, and, together with hydrogen chloride sprayed, the mercury is reduced.

A method for removing mercury in flue gas, the method comprising:

• removing nitrogen oxide in flue gas discharged from an industrial boiler, and spraying hydrogen chloride into the flue gas, so as to oxidize mercury;
• neutralizing with an alkali agent dilute hydrochloric acid discharged after the hydrogen chloride is produced;
• and
• supplying neutralized chloride to a fuel, and then combustion the chlorine in the boiler to produce hydrogen chloride in flue gas, and removing the mercury together with hydrogen chloride sprayed.