Industrial-Scale Application of Amine-Based Tail Gas Oxidation-Absorption Technology Combined with Claus Process for Lowering Sulfur Dioxide Emission from Natural Gas Purification

Abstract

Natural gas emits less air pollutants and carbon emissions than other fossil fuels, thereby natural gas consumption is growing rapidly and natural gas purification becomes more important around the world. Claus process and extended Claus process (e.g., superClaus, cold bed adsorption and clinsulf-SDP) are industrialized sulfur recovery systems to convert hydrogen sulfide to sulfur and have been widely used in natural gas purification plants, but there would be a large number of sulfur dioxide emissions. To reduce sulfur dioxide emissions, an innovative tail gas oxidation-absorption technology combined with Claus process has been developed and applied in a natural gas purification plant of PetroChina. In this paper, the tail gas oxidation-absorption technology combined with Claus process was elucidated in detail, an amine-based sulfur dioxide absorbent was employed and evaluated, and key operation parameters such as oxygen volume fraction, burner temperatures, amine-based sulfur dioxide absorbent concentrations, pH of lean amine solution and molar rate of heat stable salts versus the amine-based sulfur dioxide absorbent were investigated and analyzed in an industrial-scale. The key operation parameters were determined as follow. Tail gases of the sulfur recovery system was burned at 810±5°C in a burner, and the oxygen volume fraction was maintained between 3.3v% and 3.7v%. The concentration of amine-based sulfur dioxide absorbents was controlled between 21w% and 25w%. The pH of lean amine solution was optimized among 5.0 to 5.7. In addition, the molar rate of heat stable salts versus the amine-based sulfur dioxide absorbent was controlled between 11:10 and 14:10. As a result, with above operation strategies, super low sulfur dioxide emissions can be gotten below 100mg/m3, which is better than the sulfur dioxide discharge standard of natural gas purification plants (GB39728-2020) in china. Wastewater produced from the amine-based tail gas oxidation-absorption technology was reused. This work would be helpful for exploiting high-sulfur natural gases and decreasing sulfur dioxide emissions from natural gas purification plants in the world.