Objective The aim is to solve the problem that a triethylene glycol(TEG) dehydration unit on an offshore platform could not meet the dehydration requirements.

Methods Based on the actual production data, the simulation analysis of the process system was carried out by HYSYS software to found out the causes of the operation problems of the system.

Results The high water content in the natural gas at the inlet of the dehydration tower is the main factor affecting the effect of the dehydration system. Both the inlet filter separator and the reboiler should be considered in the transformation plan. Combined with the actual situation of the platform, the transformation scheme was finally determined to replace the inlet filter separator filter element and the electric heater of reboiler. After the transformation, the dew point of dry gas water at gauge pressure of 5.2 MPa was reduced from 6 ℃ to -23 ℃ which achieved the expected effect and reserved the operation space for subsequent expansion.

Conclusions The reason why the processing capacity of the TEG dehydration unit on the offshore platform cannot reach the design value might be that the performance of the inlet filter separator was not up to standard, which leads to the excessive water content of the natural gas at the inlet of the dehydration tower. It was suggested that the processing index of the inlet filter separator should be strictly controlled during the process design of the TEG dehydration unit, and the TEG dehydration device should be matched according to the treatment index of the inlet filter separator.