High-temperature high-concentration sulfur dioxide tail gas desulfurization system and method

The invention discloses a high-temperature high-concentration sulfur dioxide tail gas desulfurization system and method. High-temperature high-concentration SO2 tail gas is converted into tail gas at the temperature ranging from 200 DEG C to 250 DEG C after heat exchange is conduced through a waste heat boiler, converted into tail gas at the temperature ranging from 120 DEG C to 130 DEG C after heat exchange is conducted through a three-in-one tower, converted into tail gas at the temperature being 50 DEG C and the concentration below 50 mg/m after making countercurrent contact with desulfurization semi-poor alkali liquor after being quickly cooled, and exhausted after being heated to more than 100 DEG C. The desulfurization semi-poor alkali liquor absorbs SO2 in the three-in-one tower to become rich liquor and then is pumped into a regeneration reaction still, desulfurizing extractant regeneration is conducted in the regeneration reaction still, and regenerated clear liquor is poor alkali liquor and directly flows into an alkali liquor containing tank. The occupied area is small, the desulfurization efficiency is high, operation and maintenance are convenient, new waste liquor, new waste residues and new waste gas are not generated in the treatment process, by-product desulfurization gypsum can serve as building raw materials, wide application prospects are achieved, and the purpose of cyclic economy is achieved.