Objective The aim is to find the bottleneck problem restricting the long-term operation of high-sulfur natural gas purification plant by the risk assessment technology, and an effective solution is proposed to realize the long-term safe and reliable operation of high-sulfur natural gas purification plant.

Methods Starting from the safety management of the process system of the plant, the joint analysis method of HAZOP/LOPA/SIL was adopted to evaluate and quantify the risks of the plant in the process of "the double standard reconstruction project" which was designed to ensure the product temperament and tail gas discharge satisfying the latest standards. The SIL verification and calculation of the liquid level interlocking loop of the regeneration tower were carried out by using reliability block diagram and fault tree method.

Results Combined with the practical case of the natural gas purification plant, two feasible measures of improving the SIL grade and adopting double-face mechanical seal for the pump were put forward from the aspects of SIS and essential safety.

Conclusion The risk assessment technology can provide technical support for the long-term operation of the natural gas purification plant.