Application of extended NRTL equation for ternary liquid-liquid and vapor-liquid-liquid equilibria description

Simulation of a hydrocarbons mixture separation by extractive distillation was based on binary vapor-liquid as well as liquid-liquid equilibrium data. Sulfolane was considered as extractive solvent for the selective toluene separation from a model mixture with heptane. For simulation of the chosen hydrocarbons mixture separation in the presence of an extractive solvent, the NRTL model was considered. A set of temperature-dependent binary NRTL parameters was evaluated independently by fitting the experimental vapor-liquid and liquid-liquid equilibrium data of the respective binary subsystems. In order to improve the description of the ternary vapor-liquid equilibrium, original NRTL model extended by the ternary contribution term was used. Parameters of the ternary contribution were obtained by direct fitting of available ternary liquid-liquid equilibrium data while employing the original binary NRTL parameters. Quality of the ternary vapor-liquid-liquid equilibrium description using the original and the extended excess Gibbs energy models was assessed by comparing the calculated compositions of conjugate liquid phases with experimental data. Using the extended NRTL model, mean deviation of the computed mole fractions decreased by approximately four times (9.73 × 10−3) compared to the value obtained using the original NRTL model. Both original and extended NRTL models were employed for the simulation of a model mixture separation by extractive distillation. At chosen experimental conditions, high purity distillate (x 1 > 0.999) was obtained. Results of the aromatics extractive distillation in the presence of sulfolane were compared to those obtained with N-methylpyrrolidone as the extractive solvent.

Ternary Corrections in the Liquid-Liquid Equilibria Computation for Three-Component Systems Containing Components of Mixed Solvent N-Methylpyrrolidone-Ethylene Glycol

Presented are the liquid-liquid (L-L) equilibrium data for three-component heterogeneous systems toluene-N-methylpyrrolidone-ethylene glycol, heptane-N-methylpyrrolidone-ethylene glycol and heptane-toluene-ethylene glycol at 50 °C. Equations for the excess Gibbs energy (NRTL. Novák modification of Wilson equation and Redlich-Kister 4th order expansion) extended by ternary universal contribution were employed for correlating the L-L equilibrium data. The binary equation parameters were independently evaluated from the binary equilibrium data. The presented ternary data served for evaluation of parameters of the universal ternary contribution.

Ternary Corrections in the Liquid-Liquid Equilibria for Four-Component System Heptane-Toluene-N-Methylpyrrolidone-Ethylene Glycol

Prediction for four-component liquid-liquid equilibrium is based on binary a ternary equilibrium data. Three-parameter equations for the excess Gibbs energy (NRTL equation, Redlich-Kister 4th order expansion and Wilson equation in Novák modification) extended by universal ternary contribution were employed for a thermodynamic description of the four-component system. The computation method was applied for a model four-component system heptane-toluene-N-methylpyrrolidone-ethylene glycol, t = 50 °C. The computed equilibrium data were compared with experimental ones measured for the weight ratio of the mixture N-methylpyrrolidone per ethylene glycol 20/80, 40/60 and 60/40.

Extension of a lattice model of electrolytes to a ternary system of a salt and two solvents. The system CH3OH-H2O-LiCl

A lattice model proposed to describe the thermodynamic properties of binary electrolyte solutions over the whole concentration range has been extended to ternary systems involving two solvents. The relationships derived for the excess Gibbs energy and the activity coefficients of all the components have been tested with published experimental data on vapour pressures of methanol and water in the system CH3OH-H2O-LiCl at 60 °C. Examination of the ability of the model to predict the behaviour of the ternary system on the basis of binary data has shown that the expression for the excess Gibbs energy must be extended to include a ternary contribution.