New prediction method for ternary solid-liquid-vapor equilibrium from binary data

摘要

A new method is presented in this paper for predicting ternary solid-liquid-vapor equilibrium (S-L-V-E) compositions from the binary interaction constants of the (CO2 + solvent) system in the Peng-Robinson (P-R) equation of state (EOS) and the solid solubility in the solvent at a reference pressure. This method first employs calculation of the mole fraction of the solid solute in the ternary liquid mixture as proportional to the partial molar volume fraction (PMVF) of the solvent, that is, the contribution of the solvent to the molar volume of the binary (CO2 + solvent) mixture. Subsequently, vapor-liquid equilibrium (V-L-E) computations are employed for the other two components. The method has been verified in this paper for two ternary systems: G) CO2 + toluene + naphthalene and (ii) CO2 + toluene + phenanthrene. The predicted bubble point pressures at S-L-V-E are found to agree well with the corresponding experimental data from the literature within AARD of +/- 3.11 % and +/- 1.15 %, respectively, for the two ternary systems at 298 K over the pressure range of (14.9 to 62.4) bar. The P-T trace at S-L-V-E also agrees well with the reported trends. The effects of pressure and temperature on ternary-phase diagrams generated by this method are utilized for the assessment of crystallization pathways.