Abstract: The technology of complex iron desulfurization (CTS) applied in the tail gas upgrading unit of the sulfur recovery joint plant of Petrochina Sichuan Petrochemical Co., Ltd. was introduced. This paper expounded the improvement measures forthe problems that affected the operation cycle,safety and environmental protection of the plant were described, including the use of high efficiency desulfurization solvent, CTS reactor upgrading, replacement of CTS unit circulating solution additives, filter cloth optimization and technological transformation of sulfur-containing tail gas. Through the implementation of the above improvement measures, the mass concentration of H₂S entering the reactor was significantly reduced, the number of breakthrough times of sulfur accumulation in the reactor was significantly reduced, the quality of the circulating solution was significantly improved, the amount of sulfur powder filtered out of the filter increased by 3 times as compared with that before modification, and the exhaust gas achieved long-term ultra-low emission standard. After the implementation of the above improvement measures, the problems in the operation of the CTS unit were completely solved, the key parameters of the device were stable, the total sulfur recovery rate was significantly increased, and the sulfur device was safe and environmentally friendly for a long period of operation, which could be used as a reference for the technical transformation of similar devices.

Key words: complex iron desulfurization process, sulfur recovery, sulfur-containing tail gas, high efficiency desulfurizing solvent