A new approach was presented to improve the simulation results of an existing TEG based natural gas dehydration plant, using Aspen Plus software. Furthermore, the environmental impact of the plant was investigated. The plant consists of four main unit operations including an absorber, a flash tank, a stripper and a regenerator. Twelve thermodynamic models were assigned to these units. In the first step of the study, only one thermodynamic model was assigned to all of the units while in other steps, combinations of thermodynamic models were employed. The most accurate model combination was found to be RKSMHV2 for the absorber and stripper and PSRK for the flash tank and regenerator. It was found that a proper combination of thermodynamic models may improve the simulation results. As solvent circulation rate increased, BTEX, VOC and greenhouse gas emissions enhanced. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.