Abstract:

In order to analyze the SO₃ emission characteristics of coal-fired units, testing the generation and removal of SO₃ for the 58 units, analyze the generation of SO₃ from combustion in the furnace, the conversion of SO₂/SO₃ from denitration system, and the removal effect of SO₃ for dry dust remover, wet desulfurization system, and wet dust remover, so as to obtain the rule of generation, migration, and removal of SO₃ in coal-fired units. The results show that the generation of SO₃ in coal-fired units is mainly composed of the combustion of coal sulfur and the conversion of SO₂ in the denitration system. The generation rate of SO₃ during furnace combustion is approximately 1% of the total amount of SO₂ generated during furnace combustion, and the conversion rate of SO₂/SO₃ in the denitration system is also at 1%. The electrostatic precipitator, electrostatic bag precipitator and wet desulfurization system have limited removal effect on SO₃. The removal efficiency of electrostatic precipitator, electrostatic bag precipitator and wet desulfurization system is 15%~25%, 20%~40% and 40%~60%. The low temperature dust remover and wet dust remover have high SO₃ removal efficiency. The SO₃ removal efficiency of low temperature dust remover is 50%~80%, and that of wet dust remover is 70%~90%. Therefore, the generation of SO₃ can be effectively controlled by controlling the sulfur content of coal combustion or the SO₂/SO₃ conversion rate of the catalyst in the denitration system. At the same time, low temperature dust collectors and wet dust collectors can be used to control the emission of SO₃, and SO₃ can be controlled below 10mg/m³ through the dry dust collectors, wet desulfurization system, and wet dust collectors.

Key words: SO₃ generation, SO₂/SO₃ conversion, dry dust remover, wet desulfurization system, wet dust remover