Device for desulfurizing flue gas by using sodium-calcium dual alkali method

The utility model discloses a flue gas desulfurization device, in particular to a device for desulfurizing flue gas by using a sodium-calcium dual alkali method. The utility model provides a device for desulfurizing flue gas by using a sodium-calcium dual alkali method, which can be used for oxidizing sulfite more completely to obtain high-quality gypsum. The device comprises a desulfurizing and absorbing tower, a replacing reactor and an oxidizing tank, wherein the desulfurizing and absorbing tower is provided with a sulfur-containing flue gas inlet, a purified flue gas exhaust hole, a desulfurizing pregnant solution outlet and a desulfurizing liquid inlet; the replacing reactor is provided with a liquid inlet, a reactant outlet and a slime inlet; the oxidizing tank is provided with a pre-oxidization desulfurizing pregnant solution inlet, an after-oxidation desulfurizing solution outlet, an air inlet and an air outlet; the desulfurizing pregnant solution outlet of the desulfurizing and absorbing tower is con