Christos Boukouvalas

Prediction of Vapor-Liquid-Equilibrium with the Lcvm Model - A Linear Combination of the Vidal and Michelsen Mixing Rules Coupled with the Original UNIFAC and the T-Mpr Equation of State

Abstract Boukouvalas, C., Spiliotis, N., Coutsikos, P., Tzouvaras, N. and Tassios, D., 1994. Prediction of vapor-liquid equilibrium with the LCVM model: a linear combination of the Vidal and Michelsen mixing rules coupled with the original UNIFAC and the t-mPR equation of state. Fluid Phase Equilibria, 92: 75-106. A new mixing rule, a linear combination of the Vidal and Michelsen rules, for the attractive term parameter in cubic equations of state (EoS) has been developed. This mixing rule, coupled with a translated and modified Peng-Robinson EoS and the original UNIFAC, leads to the LCVM model which provides successful prediction of vapor-liquid equilibria (VLE) of nonpolar and polar systems at low and high pressures. This also applies to systems of dissimilar component size, such as those containing gases (C2H6, CO2 and CH4) with large n-alkanes, where other EoS/GE predictive models, such as MHV2 and PSRK, perform poorly.

The selective dissolution/precipitation technique for polymer recycling: a pilot unit application

In this study, the selective dissolution/precipitation method for polymer mixture separation and recycling is evaluated. The method was successfully applied in a pilot unit designed and developed for the separation of polymer mixtures. Recycled polymers of comparable quality with that of the pre-used ones were recovered. Furthermore, the feasibility study for high-capacity units indicated the applicability of this technique from the economic point of view.

The performance of EoS/GE models in the prediction of Vapor-Liquid Equilibria in asymmetric systems

Abstract An extensive comparison of four EoS/GE models: LCVM, MHV2, PSRK and Wong-Sandler in the prediction of Vapor-Liquid Equilibria (VLE) in asymmetric systems is presented and demonstrates that only LCVM yields satisfactory results.

Application of the LCVM model to multicomponent systems: Extension of the UNIFAC interaction parameter table and prediction of the phase behavior of synthetic gas condensate and oil systems

Abstract The LCVM model of Boukouvalas et al. (1994) uses the translated and modified Peng—Robinson equation of state (EoS) coupled with the Original UNIFAC excess Gibbs energy ( G E ) model and introduces a new mixing rule (a linear combination of the Vidal and Michelsen ones) for parameter a in the attractive term of the EoS. The UNIFAC parameter table is here extended to include several gas/CH 2 , gas/ACH, gas/ACCH 2 , and gas/gas pairs. Correlation and prediction results for binary systems are very satisfactory, including systems with large size differences of their components — where other EoS/ G E models fail — as well as at very high pressures (up to 2000 bar). These parameters are then applied to the prediction of bubble- and dew-point pressures, K values and volume percent liquid (VPL) of synthetic gas condensate and oil systems. Very satisfactory results are again obtained except, as expected, in the high pressure section for VPL of gas condensates. The results are comparable with models using conventional mixing rules with regressed binary parameters, and again superior to other EoS/ G E models.

APPLICATION OF SUPERCRITICAL FLUID EXTRACTION IN INDUSTRIAL WASTE TREATMENT : THERMODYNAMIC MODELING AND DESIGN

ABSTRACT The use of supercritical fluid extraction (SFE) as a separation process for the treatment of industrial wastewater is examined. The performance of the LCVM EoS/GE model in thermodynamic modeling of the systems CO2/H2O/organic pollutant (aromatics, phenol, cresol), including the presence of a cosolvent, is evaluated. The design of a unit that processes the water/phenol system with carbon dioxide, with and without a cosolvent, is also examined. The use of a cosolvent is a very important parameter for the SFE process since it can cause a significant decrease in the total cost of the unit. Application of the process appears limited due to the lack of predictive models and the high cost of equipment.

Comparison of the performance of the LCVM model (an EoS/GE model) and the PHCT EoS (the Perturbed Hard Chain Theory Equation of State) in the prediction of the Vapor–Liquid Equilibria of binary systems containing light gases

Abstract The purpose of this work is to compare two models, which are able to perform Vapor–Liquid Equilibrium (VLE) predictions. The first one, the LCVM model, is an EoS/G E one and it has been successfully applied in the prediction of the VLE behavior of polar and non-polar systems, as well as, systems of dissimilar component size, such as those containing gases with large n -alkanes. The second one is PHCT, an equation of state based on the perturbed hard chain theory. It has also been successfully applied in binary systems of supercritical fluids and non-polar molecules and in systems containing light gases and large n -paraffins. The comparisons results presented in this paper, proved that the two models are comparable, concerning the ability to predict the VLE, as well as, the volumetric behavior of systems with low to medium component size difference (supercritical fluids with non-polar components up to about 10 carbon atoms). However, as the size difference increases, LCVM performs better, especially in the near critical region of such systems.

Recovery of near-anhydrous ethanol as gasoline additive from fermentation products

Abstract The use of near-anhydrous ethanol, obtained from fermentation products through low pressure distillation, as a gasoline additive is examined. To this purpose, a reliable model for predicting the azeotropic composition of an ethanol-water mixture as a function of the pressure is presented. It is developed by considering the available thermodynamic consistent experimental data and using the Wilson and the Virial equations for the liquid- and vapor-phase nonideality, respectively. It is concluded that, for an area with no extremely cold winters—minimum ambient temperature −20°C—alcohol with 96.5% (wt) purity can be used in a 90/10 (vol) gasohol mixture. Such an alcohol can be produced with a single distillation column operating at 140 mmHg pressure with an energy consumption of 5150 kJ/kg of product; or with a system of two columns with lower energy consumption but higher capital cost. These energy consumptions are very sensitive to the accuracy of the predicted azeotropic composition at the operati...

BENCH-SCALE APPLICATION OF SUPERCRITICAL FLUID EXTRACTION FOR THE REMOVAL OF PHENOL FROM AQUEOUS SOLUTION

The supercritical fluid extraction of phenol, a common pollutant, from aqueous solutions is performed in a bench-scale extraction apparatus through the use of supercritical CO2 at 150 bar and 45°C. The obtained results are satisfactory, and the influence of pressure and flow rate of supercritical CO2, as well as the co-solvent effect, are examined. Finally, the LCVM (Linear Combination of Vidal and Michelsen) mixing rules model, an EoS/Ge (Equation of State/Gibbs free energy) one, thermodynamic model with new interaction parameters, combined with a simple mathematical one, is used successfully for the correlation of the experimental results by adjusting the overall volumetric mass transfer coefficients of the process.