Semi-empirical correlation for binary interaction parameters of the Peng-Robinson equation of state with the van der Waals mixing rules for the prediction of high-pressure vapor-liquid equilibrium

Abstract

Peng-Robinson equation of state is widely used with the classical van der Waals mixing rules to predict vapor liquid equilibria for systems containing hydrocarbons and related compounds. This model requires good values of the binary interaction parameter kij . In this work, we developed a semi-empirical correlation for kij partly based on the Huron-Vidal mixing rules. We obtained values for the adjustable parameters of the developed formula for over 60 binary systems and over 10 categories of components. The predictions of the new equation system were slightly better than the constant-kij model in most cases, except for 10 systems whose predictions were considerably improved with the new correlation.

Keywords: Binary interaction parameters; Mixing rules; Peng–Robinson equation of state; Vapor–liquid equilibrium.

Fig. 1

Pxy equilibrium diagram for ethane and hydrogen sulfide at 255 and 283 K using the semi-empirical correlation for k_ij (solid line) (θ = [2.4607 0.80676 −0.06293]) as compared with the results of the constant-k_ij calculations (dotted line) (k_ij = 0.0833) and with published experimental data (markers) . The pressure data points are within 0.1 bar.

Fig. 2

Pxy equilibrium diagram for methane and toluene at 313 K using the semi-empirical correlation for k_ij (black solid line) (θ = [1.5806 1.3061 0.2421]) as compared with the results of the constant-k_ij calculations (red dotted line) (k_ij = 0.097) and with published experimental data (markers) . The pressure data points are within 1 bar.

Fig. 3

Pxy equilibrium diagram for nitrogen and ethane at 172 and 220 K using the semi-empirical correlation for k_ij (solid line) (θ = [1.8177 1.1792 0.1195]) as compared with the results of the constant-k_ij calculations (dotted line) (k_ij = 0.0515) and with published experimental data (markers) .

Fig. 4

Pxy equilibrium diagram for methane and carbon dioxide at 250 and 270 K using the semi-empirical correlation for k_ij (solid line) (θ = [2.5522 0.81726 0.0819]) as compared with the results of the constant-k_ij calculations (dotted line) (k_ij = 0.0919) and with published experimental data (markers) .

Fig. 5

Ternary liquid vapor equilibrium diagram for methane, carbon dioxide and propane at 270 K and 55 bar using the semi-empirical correlation for k_ij as compared with the results of the constant-k_ij calculations and with published experimental data . The scale of axes is in mole %.

Fig. 6

Ternary liquid vapor equilibrium diagram for nitrogen, carbon dioxide and ethane at 270 K and 60 bar using the semi-empirical correlation for k_ij as compared with the results of the constant-k_ij calculations and with published experimental data . The blue line/markers represent the experimental data, the red lines/markers represent the results of this work and the green lines/markers represent the results of the constant-k_ij calculations.

Fig. 7

Ternary liquid vapor equilibrium diagram for nitrogen, carbon dioxide and ethane at 220 K and 8 bar using the semi-empirical correlation for k_ij as compared with the results of the constant-k_ij calculations and with published experimental data . The blue line/markers represent the experimental data, the red lines/markers represent the results of this work and the green lines/markers represent the results of the constant-k_ij calculations.