Flue gas softening pretreatment device and method for desulfurization wastewater

The invention discloses a flue gas softening pretreatment device for desulfurization wastewater. The device comprises a preliminary wastewater softening tank, a sedimentation tank A, a wastewater aeration and softening tank, a sedimentation tank B, a pH adjusting tank and an air blower, wherein a stirring device and an online pH monitor A are arranged in the preliminary wastewater softening tank, and a sludge discharge port is formed in the bottom; a sludge discharge port is formed in the bottom of the sedimentation tank A; an aeration device A and an online pH monitor B are arranged in the wastewater aeration and softening tank, and a sludge discharge port is formed in the bottom; a sludge discharge port is formed in the bottom of the sedimentation tank B; an aeration device B and an online pH monitor C are arranged in the pH adjusting tank; the air blower is connected with the wastewater aeration and softening tank, the pH adjusting tank and a flue gas heat exchanger. The device has the benefits as follows: CO2 in flue gas is effectively utilized, waste heat of the flue gas is reduced, and thermal pollution caused by the flue gas of power plants is reduced while carbon emission is reduced; the flue gas used for softening is pre-cooled, so that evaporation of a large quantity of moisture and droplet entrainment caused by the high temperature of the flue gas in the aeration and softening process of the flue gas are effectively reduced; the equipment cost is reduced, and safety is improved.