Modeling vapor-liquid phase equilibria of methane-water and methane-carbon dioxide-water systems at 274K to 573K and 0.1 to 150 MPa using PRSV equation of state and Wong-Sandler mixing rule

Abstract Attempts were made in this study to accurately correlate mutual solubilities of the CH 4 -H 2 O and the CO 2 -CH 4 -H 2 O systems with a conventional two-phase flash method using cubic equation of state. A new set of model parameters for the CH 4 -H 2 O binary pair were presented for our previous published PRSV + WS (NRTL) model to enable flash calculation and stability analysis for the CH 4 -H 2 O and the CO 2 -CH 4 -H 2 O systems over the temperature and pressure ranges of 274–573 K and 0.1–150 MPa. The temperature corresponding to the minimum methane solubility in the aqueous phase is found around 345 K and this temperature is almost no change when pressure changes from 20 to 140 MPa for the CH 4 -H 2 O system. This observation is supported by both modeling results and experimental data. The model performance for the CH 4 -H 2 O and CO 2 -CH 4 -H 2 O systems was validated by a large amount of experimental data available to us and two previous published models (DM2006 and SW1992). As for the CH 4 -H 2 O system, the average absolute deviation of model calculated phase composition from the experimental data is around 4% for the gas phase and 7% for the aqueous phase. The phase equilibrium of a ternary system (i.e. CO 2 -CH 4 -H 2 O) can be reasonably well predicted by use of interaction parameters per binary pair (CO 2 -CH 4 , CO 2 -H 2 O, and CH 4 -H 2 O). A web-based computational tool for the proposed model is also provided (Supplementary Information).