Modified Soave–Redlich–Kwong Equation of State for Phase Equilibrium Modeling: A Case of a Petroleum Residue and n-Pentane Mixture under Sub- and Supercritical Conditions

The objective of the present numerical investigation is to develop an advanced approach for modeling the phase equilibrium of a vacuum residue (VR)–n-pentane system. Simulations are performed using the cubic Soave–Redlich–Kwong (SRK) equation of state (EoS), which is refined in terms of calculating binary interaction parameters (BIPs). The calculation of BIPs, reflecting the effects of molecular weight and aromaticity factor of fractions, is supplemented by their temperature dependence. In addition, it is found necessary to account for the intermolecular interaction between aromatic fractions by incorporating into the model the BIPs for aromatics–light resin (LR), light resin–heavy resin (HR), light resin–asphaltene, and heavy resin–asphaltene pairs. The yield of the deasphalted oil (DAO) obtained by batch one-step extraction at different temperatures and solvent-to-VR ratios and the content of metals in deasphalted oil are used for validating the model as experimental parameters. The results of phase equilibrium simulations agree well with the experimental data under sub- and supercritical conditions for n-pentane. The developed approach holds promise for the modeling of petroleum residue systems comprising other low-molecular-weight alkanes and encountering higher temperatures required for supercritical solvent regeneration.