Cause analysis and countermeasures of discharged flue gas of sulfur recovery unit exceeding standard

This paper analyzed the reasons for exceeding standard of sulfur dioxide mass concentration in discharged flue gas from 20×10³ t/a sulfur recovery unit of Kingao (Hubei) Science & Technology Chemical Industry Co., Ltd. Corresponding revamping measures were adopted, which included: (1) Introducing the off gas from liquid sulfur tank to the combustion furnace; (2) using desulfurization solvent with better desulfurization performance; (3) using catalysts with better organic sulfur hydrolysis ability; (4) adding a caustic wash tower cascaded to the tail gas absorber. After implementing the former measures (1)(2)(3) and adjusting the local process parameters, the SO₂ mass concentration in discharged flue gas was less than 100 mg/m³.