Abstract: At present, there are problems such as over-standard SO₂ emission from the sulfur recovery unit of a natural gas purification plant in Jingbian Gas Field. In order to solve this problem, this article aims to improve the conversion rate of H₂S and reduce the emission of SO₂. On the basis of the traditional Clinsulf-DO process, the optimization design is carried out from the aspects of process flow and catalyst. As a result, a dual-reactor selective sulfur oxidation recovery process plus tail gas alkaline washing technology is formed. In this process, domestic catalysts HS-35 and HS-38 are used for catalytic reaction in the the first and second reactors, respectively. The results of calibration data show that the total sulfur conversion rate of the retrofitted plant has been increased from 80.27% of the original process to over 94%. At the same time, the mass concentration of SO₂ in the emitted tail gas is reduced to below 100 mg/m³, which can meet the requirements of the new environmental protection regulations "Petroleum Refining Industry Pollutant Emission Standard (GB31570-2015)". This technology has good industrial application effects, so it can provide a certain reference for sulfur recovery from low H₂S acid gas to satisfy gas emission standards.

Key words: sulfur recovery, catalyst, alkaline wash, selective oxidation