High Pressure Phase Equilibrium of (Solvent + Salt + CO2) Systems by the Extended Peng-Robinson Equation of State

Abstract

An extended Peng-Robinson equation of state (EPR-EOS) is used to model the vapor-liquid equilibrium (VLE) in systems containing (water + NaCl + CO2), (water + methanol + NaCl + CO 2), (water + Na 2SO4 + CO 2) and (water + NH 4Cl + CO2). The binary and ternary interaction parameters between salt and solvent are adjusted to experimental mean solvent activity of salts (NaCl and Na2SO4). For the system containing (water + Na2SO4 + CO2), the EPR-EOS is used to predict the P-T diagram when the moles of Na 2SO4 in 1 kg water are 0.25, 0.5 and 1. The calculated results for the (water + Na2SO4 + CO2) system by the extended PR-EOS are compared with the correlation results by Anderko-Pitzer EOS. The average absolute deviation of (ΔP/Pexp) % between the correlation results by Anderko-Pitzer EOS and experimental data is 8.4 % while this value for extended PR-EOS is 6 %. The P-x diagram for (water + NH 4Cl + supercritical-CO2) system at temperatures (333 and 353 K) are also obtained and compared with the calculation results by VTPRLIFAC model. The average absolute deviation between calculation results by VTPRLIFAC model and experimental data is 7.8 % but this value for our calculations is 6.2 %.