Application of a new cubic equation of state to computation of phase behavior of fluids and asphaltene precipitation in crude oil

In this study, a new equation of state has been presented based on the perturbation theory. The vapor phase volume, liquid density, saturation pressure enthalpy and entropy of 20 pure components have been calculated by this new EOS. The average absolute deviations of the predicted saturation pressure, liquid density and vapor phase volume are 0.64, 2.69 and 2.390%, respectively. Also, liquid densities of n-alkanes (C1–C20) have been estimated by the new EOS whose average absolute deviation is 4.3%. The obtained results have been compared to PR and M–PR equations of state and the accuracy of the new EOS has been approved. Then, the Flory–Huggins model has been modified for prediction of the amount of asphaltene precipitation in crude oil. The estimated amounts of asphaltene precipitation by this model and the new EOS have been compared to the amounts obtained by the Flory–Huggins model and the experimental data. This comparison shows that the modified Flory–Huggins model is more accurate for prediction of asphaltene precipitation in crude oil.