Objective Solve the shutdown and maintenance problem caused by frequent leakage of regeneration gas air-cooler in the molecular sieve dehydration unit.

Methods The reasons for the leakage of the air-cooler were analyzed and calculated from the aspects of the material, vibration and pipeline stress of the regeneration gas air-cooler, and the HYSYS and CAESAR Ⅱ software were used to check and calculate the influence of the high-temperature regeneration gas entering the high-pressure venting system on the temperature, strength, stress and thermal displacement of the pipeline, valve and equipment in the new process flow.

Results It is feasible to connect the high-temperature regeneration gas from the inlet of the regeneration gas air-cooler to the regeneration gas pressure regulating and venting pipeline, and it will not affect the pipeline, valves and equipment of the venting system.

Conclusions The reason for the leakage of the regeneration gas air-cooler is the unqualified material and the unreasonable arrangement of the inlet and outlet pipelines. Adding a section of venting pipeline at the inlet of the regeneration gas air-cooler can realize non-stop maintenance. It is suggested that the natural gas purification plant should strictly review the material of the equipment when purchasing the regeneration gas air-cooler and reasonably arrange the inlet and outlet pipelines in order to reduce the leakage failure rate of the regeneration gas air-cooler.