Vapor–Liquid Equilibrium Measurements and Cubic-Plus-Association Modeling of Triethylene Glycol Systems

Due to the low vapor pressure of triethylene glycol, there is limited vapor–liquid equilibria data involving this component at high pressure. Aiming to expand this experimental database, new vapor–liquid equilibria data points were measured for the systems: triethylene glycol (1) + methane (2), triethylene glycol (1) + ethane (2), triethylene glycol (1) + ethane (2) + water (3), and triethylene glycol (1) + gas mixture (2). The experimental ranges were within the relevant process conditions for the natural gas dehydration, with T = (293.15, 333.15) K, and P = (3.0, 18.0) MPa. The new data include both gas and liquid phase compositions with relative experimental uncertainties (u r) below 0.17. Furthermore, the Cubic-Plus-Association (CPA) using the 4C association scheme for triethylene glycol (TEG) and only one interaction parameter per binary has provided a qualitative description of the newly measured data, with average absolute relative deviation (AARD) ranging between 3% and 54%.