Objective The aim is to solve the problems of high water dew point of dry purified gas and high energy consumption of triethylene glycol (TEG) dehydration unit in a natural gas purification plant.

Method Field experiments and numerical simulation methods were used to deeply explore the optimization and technical improvement directions of TEG dehydration unit process parameters.

Result Firstly, the influences of on-site filters, regeneration system and other equipment on the TEG solution were excluded. The water dew point of dry purified gas was mainly affected by three factors: the temperature of wet purified gas into the unit, the temperature of reboiler and the temperature of lean liquid into the absorber. The order of influence degree from large to small was: the temperature of wet purified gas into the unit ＞ the temperature of reboiler ＞ the temperature of lean liquid into the absorber. Secondly, the energy consumption of the TEG dehydration unit was positively correlated with the reboiler temperature, the temperature of the rich liquid into the regenerator and the TEG circulation volume. The energy consumption of the on-site TEG dehydration unit was mainly controlled by the reboiler temperature. Thirdly, on the premise of ensuring that the purified gas water dew point in winter and spring was not higher than −8 ℃ and in summer and autumn not higher than 0 ℃, respectively, it was recommended to adopt the working mode of wet purified gas into the unit temperature of 22.52 ℃, reboiler temperature of 164 ℃ and lean liquid into the absorber temperature of 49.24 ℃ in summer and autumn, and the working mode of wet purified gas into the unit temperature of 15.00 ℃, reboiler temperature of 168.98 ℃ and lean liquid into the absorber temperature of 41.57 ℃ in winter and spring. Under this working mode, the energy consumption of the unit was reduced by 42.60% and 47.57%, respectively. Fourthly, Relying only on theoretical optimization of process parameters could not meet the needs of practical applications. It was recommended that the performance of cooling equipment for both wet purified gas and TEG should be improved. This would help reduce the high temperature effects of wet purified gas and TEG lean liquid, thereby minimizing the cost issues associated with excessive use of high-load reboilers.

Conclusion By implementing the above measures, the water dew point of dry purified gas and the energy consumption of the unit can be reduced, which can provide a reference for the optimization of the TEG dehydration process.