Influence factors and countermeasures of sulfur dioxide emission in flue gas of sulfur recovery unit

The reasons for exceeding standard of sulfur dioxide concentration in flue gas emission of30 kt /a sulfur recovery unit of Lanzhou Petrochemical Company,PetroChina were analyzed,and corresponding revamping measures were adopted. The results showed that high sulfide content in oxidation exhaust gas of gas purification unit,high sulfide content in fuel gas and poor quality of regenerated lean solution were the main factors which caused the excess emission of sulfur dioxide. By adopting the revamping measures,such as burning the oxidation exaust gas in sour gas burner instead of in sulfur recovery flue gas burner,replacing the present fuel gas with desulfurized dry gas,changing central regeneration of absorption solvent to individual regeneration,the sulfur dioxide concentration in flue gas emission decreased from more than 600 mg /m3 to less than 80 mg /m3.