Correlation and prediction of vapour-liquid equilibria in ternary systems formed by hydrocarbons

Abstract

The problem of prediction and correlation of vapour-liquid equilibria (VLE) in ternary systems has been discussed and the limitation of the applicability of the known methods for this purpose has been pointed out. The investigations on the comparison of the efficiency of the various methods for the correlation and prediction of VLE in ternary systems belonging to different classes of mixtures have been undertaken. As a part of this work, the total pressure data for 4 ternary mixtures ( n-hexane-cyclohex-ane-benzene, n-hexane-methylcyclopentane-benzene, 1-heptene- n-heptane- n-octane and cyclohexane- n-heptane-toluene) and 12 appropriate binary mixtures ( n-hexane-cyclohexane, n-hexane-benzene, cyclohexane-benzene, n-hexane-methylcyclopentane, n-hexane-benzene, methylcyclopentane-benzene, 1-heptene- n-heptane, 1-heptene- n-octane, n-heptane- n-octane, cyclohexane- n-heptane, cyclohexane-toluene and n-heptane-toluene) have been selected and correlated by means of the NRTL, the UNIQUAC and the Wilson equations. Subsequently, the ternary VLE data have been predicted using the binary parameters of the equations calculated from appropriate binary VLE data. The correlation and the prediction results have been fully discussed from the point of view of intermolecular interactions and some recommendations for the use of the investigated equations for such calculations are made.