Simulation and Optimization of the Utilization of Triethylene Glycol in a Natural Gas Dehydration Process

Abstract

Abstract The dehydration unit of a plant that processes natural gas uses triethylene glycol (TEG) as an absorbent to remove water from the gas to prevent blockages in pipes due to the formation of hydrates. Although TEG is recyclable, it is usually lost in the system due to vaporization and carryover, which results in economic issues. Therefore, it is necessary to optimize the dehydration process to achieve the allowable water concentration in the gas, to minimize the use of energy, and to minimize the loss of TEG. Experimental set was designed using Design Expert software by utilising data from Farashband gas processing plant, Iran and subsequently, fed to ASPEN HYSYS to construct and simulate the dehydration process. The chosen affecting parameters to the process were the (1) lean glycol circulation rate, (2) the temperature of the reboiler, and (3) the number of trays in the contactor column. Whereas, the response parameters included the (1) amount of glycol that was lost, (2) the reboiler duty, (3) the concentration of water in the dry gas, and the (4) temperature at which the hydrate formed. Then, these data were optimized using the response surface methodology (RSM). The results indicated that the optimum conditions within the experimental range conducted in this study of process parameters chosen, of the lean glycol circulation rate, the temperature of the reboiler, and the number of trays in the glycol contactor column for the gas dehydration process for the plant were 3944 kg/hr, 180 °C, and three trays, respectively.