Thermophysical properties of associating fluids in natural gas industry using PC-SAFT equation of state

The perturbed-chain statistical associating fluid theory (PC-SAFT) is employed to calculate the thermophysical properties of some associating fluids that are widely used in the natural gas industry. Methanol, alkanolamines, and glycols are considered in this work. The alkanolamines include monoethanolamine (MEA), diethanolamine (DEA), and methyldiethanolamine (MDEA). Two new modified associating schemes are introduced to describe the alkanolamine associating behavior. The glycols considered in this work are monoethylene glycol (MEG), diethylene glycol (DEG), and triethylene glycol (TEG). The pure component parameters of these associating fluids are determined using vapor pressure and saturated liquid density data. The heats of vaporization and heat capacities of these compounds are then predicted. Sound velocities and Joule-Thomson coefficients are additionally predicted for methanol. The results indicate that PC-SAFT is accurate for correlating the vapor pressure and liquid density of methanol, the glycols, and alkanolamines. PC-SAFT is also accurate in predicting the Joule-Thomson coefficients and sound velocities of methanol. Although PC-SAFT is not accurate enough for predicting the thermal properties (heat capacities and heats of vaporization) of MEG and TEG, it reasonably describes the thermal properties of MEA, DEA, MDEA, and DEG.