Abstract: Two-stage Claus plus hydrogenation reduction absorption and incineration process was used in conventional sulfur recovery unit, and the SO2 concentration of flue gas could not meet 100 mg/Nm3, the special emission limits stipulated in GB31570-2015 Emission Standard of Pollutants for Petroleum Refining Industry. At present, sodium desulfurization, ammonia desulfurization and SO2 recovery processes can reduce the SO2 concentration of flue gas emissions from sulfur recovery unit to no higher than 100 mg/Nm3. Through the comparison of these three processes from the aspects of project investment, production cost, energy consumption, operation risk and operation difficulty, the advantages and disadvantages of different processes are obtained.

Key words: sulfur recovery, tail gas upgrading, sodium desulfurization, ammonia desulfurization, SO2 recovery