Evaluation of Cubic, SAFT, and PC-SAFT Equations of State for the Vapor–Liquid Equilibrium Modeling of CO₂ Mixtures with Other Gases

Abstract

Accurate thermodynamic models for phase equilibria calculations of carbon dioxide mixtures with other gases are of high importance for the safe and economic design of carbon capture and storage (CCS) technologies. In this work, we assess the capability of Redlich–Kwong (RK), Soave–Redlich–Kwong (SRK), Peng–Robinson (PR) cubic equations of state (EoS), as well as Statistical Associating Fluid Theory (SAFT) and Perturbed-Chain SAFT (PC-SAFT) in modeling vapor–liquid equilibria for binary mixtures of CO2 with CH4, N2, O2, SO2, Ar, and H2S, and for the ternary mixture CO2–N2–O2. Liquid density calculations for some of these mixtures are also performed. Experimental data available are used to assess the accuracy of the models. Two different expressions are used for the calculation of parameter α in PR EoS. PC-SAFT is, on average, more accurate than cubic EoS and SAFT when no binary interaction parameter is used. However, when a binary interaction parameter fitted to the experimental data is used, model correlations from SRK, PR, SAFT, and PC-SAFT are of comparable accuracy.