Comparative study of vapour-liquid equilibrium and density modelling of mixtures related to carbon capture and storage with the SRK, PR, PC-SAFT and SAFT-VR Mie equations of state for industrial uses

Abstract

Carbon capture and storage (CCS) is nowadays considered as one of the most promising methods to counterbalance the CO2 emissions from the combustion of fossil fuels, natural gas processing, cement manufacturing, etc. In dealing with the transport and the storage of CO2-rich streams, design of a safe and optimum process requires the knowledge of thermophysical properties (especially density) of CO2-rich mixtures. Consequently, the development of accurate thermodynamic models to evaluate these properties plays a key role in the context of CCS. This work is focused on comparing the capability of four Equations of State (EoSs) in modelling the Vapour-Liquid Equilibrium (VLE) and the density of binary mixtures of interest in the field of CCS. Two Cubic EoSs (CEoS), the original Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR) EoSs, and two Statistical Associating Fluid Theory-based EoSs, namely the Perturbed Chain (PC-SAFT) EoS and the Variable Range SAFT-VR Mie EoS have been considered. These EoSs were compared (with both zero and regressed binary interaction parameters) with respect to VLE and density data of 108 binary mixtures of five main gaseous components (CO2, CH4, C2H6, N2, and H2S). Concerning the cubic EoS, the Peneloux volume translation was used to better correlate densities. The comparison reveals that on average the most accurate VLE and density predictions are obtained with the SAFT-based EoSs, while similar results in VLE calculations are obtained with the four EoSs when regressed binary interaction parameters are used. The SAFT-VR Mie EoS is on average more accurate for the description of VLE and density data than the other studied models.