Gibbs energy based procedure for the correlation of type 3 ternary systems including a three-liquid phase region

Marcilla, A.; Olaya, Marı́a del Mar; Serrano, María Dolores Marrodán; Velasco, Raul; Reyes‐Labarta, Juan A.

doi:10.1016/j.fluid.2009.04.005

Cited by 24 publications

(26 citation statements)

References 18 publications

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“…Una excelente revisión sobre la aplicación de los métodos de convergencia local y de optimización global a la solución numérica del problema del equilibrio de fases isotérmico-isobárico, puede encontrarse en el trabajo presentado por Wakeham y Stateva (2004). En la última década, sólo algunos estudios han sido enfocados al cálculo de los equilibrios líquidos multifásicos con modelos de energía de Gibbs de exceso, entre los cuales se encuentran los reportados por Stateva et al (2000), García-Sánchez et al (2001), Solokhin et al (2002), Guo et al (2004), Denes et al (2006), Marcilla et al (2009) y Kangas et al (2011. Estos autores utilizaron diferentes estrategias numéricas para encontrar la solución del problema del flash isotérmico-isobárico de sistemas ternarios y/o cuaternarios que presentan múltiples fases líquidas.…”

Section: Representación De Los Equilibrios Líquidos Multifásicosunclassified

Representación de los Equilibrios Líquidos Multifásicos de Sistemas Cuaternarios con los Modelos NRTL y UNIQUAC

García-Sánchez¹,

Justo-García²,

Águila-Hernández³

et al. 2012

Inf. tecnol.

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ResumenSe presenta el modelado de los equilibrios líquidos multifásicos de sistemas cuaternarios utilizando los modelos de coeficiente de actividad NRTL y UNIQUAC. El procedimiento numérico utilizado para calcular los equilibrios líquidos multifásicos de estos sistemas, está basado en la minimización de la energía de Gibbs del sistema con pruebas de estabilidad termodinámica para encontrar el estado más estable del sistema. Los algoritmos que se presentan para la estimación de los parámetros de interacción binaria de los modelos NRTL y UNIQUAC fueron aplicados en la correlación de datos experimentales para dos sistemas cuaternarios con dos y tres fases líquidas en equilibrio. La concordancia entre los datos experimentales y los calculados con ambos modelos termodinámicos fue satisfactoria para los dos sistemas estudiados. Palabras clave: equilibrio líquido-líquido, modelos de solución, energía de Gibbs, estabilidad termodinámica, algoritmo numérico Modeling of Multiphase Liquid Equilibria for Quaternary Systems with the NRTL and UNIQUAC Models AbstractThe modeling of multiphase liquid equilibria for quaternary systems using the activity coefficient models NRTL and UNIQUAC is presented. The numerical procedure used to calculate the multiphase liquid equilibria of these systems is based on the minimization of the system Gibbs energy in conjunction with thermodynamic stability tests to find the most stable state of the system. The algorithms presented to estimate the binary interaction parameters of the NRTL and UNIQUAC models were applied to the correlation of the experimental data for two quaternary systems with two and three liquid phases in equilibrium. The agreement between experimental equilibrium data and those calculated with both models was satisfactory for the two systems studied.

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Section: Representación De Los Equilibrios Líquidos Multifásicosunclassified

Representación de los Equilibrios Líquidos Multifásicos de Sistemas Cuaternarios con los Modelos NRTL y UNIQUAC

García-Sánchez¹,

Justo-García²,

Águila-Hernández³

et al. 2012

Inf. tecnol.

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“…5). A procedure has been proposed to separate the regions where every one of the three liquid equilibrium points must be confined [55]. The use of these LLLE restricted composition regions during the calculation or correlation of type 3 ternary systems, improves the convergence of the numerical methods that are typically very sensitive to the initial-guess values used.…”

Section: Geometrical Procedures For the Approximate Calculation Of Thementioning

confidence: 99%

“…The use of these LLLE restricted composition regions during the calculation or correlation of type 3 ternary systems, improves the convergence of the numerical methods that are typically very sensitive to the initial-guess values used. Alternatively, if the algorithm [55] evolved providing planes that progressively defined smaller regions, the LLLE solution (Fig. 5b) would be found geometrically.…”

Section: Geometrical Procedures For the Approximate Calculation Of Thementioning

confidence: 99%

GE Models and Algorithms for Condensed Phase Equilibrium Data Regression in Ternary Systems: Limitations and Proposals

Gomis¹

2011

TOTHERJ

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Phase equilibrium data regression is an unavoidable task necessary to obtain the appropriate values for any model to be used in separation equipment design for chemical process simulation and optimization. The accuracy of this process depends on different factors such as the experimental data quality, the selected model and the calculation algorithm. The present paper summarizes the results and conclusions achieved in our research on the capabilities and limitations of the existing G E models and about strategies that can be included in the correlation algorithms to improve the convergence and avoid inconsistencies. The NRTL model has been selected as a representative local composition model. New capabilities of this model, but also several relevant limitations, have been identified and some examples of the application of a modified NRTL equation have been discussed. Furthermore, a regression algorithm has been developed that allows for the advisable simultaneous regression of all the condensed phase equilibrium regions that are present in ternary systems at constant T and P. It includes specific strategies designed to avoid some of the pitfalls frequently found in commercial regression tools for phase equilibrium calculations. Most of the proposed strategies are based on the geometrical interpretation of the lowest common tangent plane equilibrium criterion, which allows an unambiguous comprehension of the behavior of the mixtures. The paper aims to show all the work as a whole in order to reveal the necessary efforts that must be devoted to overcome the difficulties that still exist in the phase equilibrium data regression problem.

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“…In previous papers [22][23][24][25][26] robust calculation methods, based on the topological analysis of the Gibbs energy of mixing function (g M = ( mix G)/RT ), were developed. The topological analysis of g M is a valuable tool that allows deducing the geometrical conditions that the g M function has to fulfil, in order to reproduce certain equilibrium behaviour in the whole composition diagram, and clearly evidences any existing calculation inconsistency.…”

Section: Introductionmentioning

confidence: 99%

“…The previously developed methods [22][23][24][25][26] resulted in a robust computer program that has allowed the determination of the capabilities and limitations of the NRTL equation [27] for correlating equilibrium data between condensed phases in ternary systems. NRTL equation was selected as representative of thermodynamic local composition models, and is one of the most frequently used model.…”

Section: Introductionmentioning

confidence: 99%

Methods for improving models for condensed phase equilibrium calculations

Marcilla

Olaya

Serrano

et al. 2010

Fluid Phase Equilibria

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a b s t r a c tLocal composition models like UNIQUAC, NRTL and the UNIFAC group contribution method are used the world over in the synthesis and design of separation processes, as well as for a large number of other applications of industrial interest. They can qualitatively describe the equilibrium behaviour of systems of different complexities but, sometimes, not with the precision required for the design of separation equipment. Regrettably, this precision is not even achieved for the LLE of many conventional type 1 and some type 2 ternary systems. High deviations in correlation results are not rare, thus showing that more capable and flexible models are needed. The analysis of the topology of the Gibbs energy of mixing function, and therefore the knowledge of the geometrical conditions that this function has to fulfil, is a valuable tool that has allowed avoiding inconsistencies in the use of the existing methods, to ascertain their capabilities and limitations to reproduce complex systems and additionally to suggest new models that improve the flexibility and accuracy needed. In this work, a simple equation based on the NRTL model, that takes into account such topological conditions, is proposed and its capabilities are tested with selected systems.

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Gibbs energy based procedure for the correlation of type 3 ternary systems including a three-liquid phase region

Cited by 24 publications

References 18 publications

Representación de los Equilibrios Líquidos Multifásicos de Sistemas Cuaternarios con los Modelos NRTL y UNIQUAC

Representación de los Equilibrios Líquidos Multifásicos de Sistemas Cuaternarios con los Modelos NRTL y UNIQUAC

GE Models and Algorithms for Condensed Phase Equilibrium Data Regression in Ternary Systems: Limitations and Proposals

Methods for improving models for condensed phase equilibrium calculations

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