Thermodynamic Modeling and Simulation of Natural Gas Dehydration Using Triethylene Glycol with the UMR-PRU Model

Dehydration of natural gas (NG) by absorption is a common industrial procedure implemented in order to avoid flow blockage and equipment breakdown. Despite the widespread use of dehydration units, few experimental data are available in the literature and most engineering practices are based on empirical correlations for the design and the determination of the optimum operational parameters. In this paper, an accurate thermodynamic model for NG mixtures, the UMR-PRU, is further extended to mixtures containing triethylene glycol (TEG) and is then used to simulate a typical NG dehydration unit using TEG by incorporating it in commercial simulators through the CAPE-OPEN standard. The results are compared with those obtained by the recommended by Aspen Hysys, TST/NRTL model. The two models calculate similar lean TEG purity, TEG circulation rate, and stripping gas rate in order to obtain the same level of dehydration, ca. 30 ppm water in the dry gas, while some differences are observed in the component distribution in the vapor and liquid phases. In addition, different reboiler duties are calculated by the two models, with those of UMR-PRU to be considered more realistic due to better prediction of the heat capacities of aqueous TEG mixtures