Wet desulphurization method for coal-fired power plant and additive used by same

The invention discloses a wet desulphurization method for a coal-fired power plant and an additive used by the same. The additive comprises the following components in percentage by weight: 70 to 80 percent of alkyl carboxylates, 5 to 10 percent of limestone active agent, 2 to 10 percent of metallic oxide and 5 to 15 percent of surfactant. The additive of the invention can improve the desulfurization effect of an absorption tower and adapt to high-sulfur coal, so that the outlet concentration of SO2 reaches the standard, and a slurry circulating pump also can be stopped in varying degrees to fulfill the aim of energy conservation; and the additive is dissolved in water easily, and the pH value is neutral, so the additive has the characteristic that the additive is easy and convenient to use, does not have air bubbles in the using process and corrode equipment. By the desulphurization method using the additive, the use amount of limestone can be reduced, the oxidization efficiency and gypsum purity of CaSO3 can be improved, the dehydration efficiency of gypsum can be improved, and NO content and Hg content in smoke also can be reduced to achieve the effects of desulfuration, denitration, demercuration and smoke purifying.