Application of improved process of blowing off residual sulfur with natural gas on sulfur recovery unit

This paper introduces the principle of improved shutdown process by using natural gas and its application on sulfur recovery unit. The process was improved from following aspects: (1) A mixture of natural gas and nitrogen for shutdown was used. The addition of nitrogen into the Claus furnace increased the amount of sulfur and heat-carrying gas during the shutdown period and shortened the downtime. (2) The air distribution during the shutdown process was determined through calculation to avoid over-temperature of the equipment and catalysts. The industrial application of Sinopec Beijing Yanshan Branch 60kt/a sulfur recovery unit showed that the flue gas SO₂ mass concentration emitted from the tail gas furnace during shutdown and blowing could be controlled within 100 mg/m³ without setting caustic washtower, which reached the discharge standard. The improved process has significant socialbenefits which can be further promoted and applied.