Predicción de equilibrio de fases líquido-líquido-líquido.
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Date
2025
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Universidad de Concepción
Abstract
En ingeniería de química es importante, tanto para sintetizar procesos como para optimizarlos, el entendimiento profundo del equilibrio de fases multicomponentes, con el fin de verificar la capacidad de generar distintas fases, ya que son limitantes a la hora de considerar las etapas de extracción de componentes puros. En particular en este trabajo se analiza una mezcla de biocombustibles que contiene butanol (1) / agua (3)/ hexadecano (3), el cual es una elección más sustentable a la hora de generar energía, pero tiene el problema de contener agua que imposibilita una buena combustión, entonces, lleva a la problemática de este escrito: ¿Cómo se puede separar el agua? Asimismo, la regla de fases de Gibbs permite, teniendo conocimientos de la cantidad de componentes y variables intensivas que se puedan fijar, evidenciar el número máximo de fases que pueda generar una mezcla multicomponente, aunque no verifica su número exacto. En este contexto entra la idea de implementar ecuaciones de estado y equilibrio, como la SAFT-γ-Mie o el balance de masa de Rachford-Rice respectivamente. Donde la primera es una formulación que descompone de la energía de Helmholtz que contiene las contribuciones necesarias para predecir el comportamiento de moléculas y mezclas, mientras que la segunda da información de la separación de dichos componentes. Entre tanto, en este trabajo se analizan equilibrios termodinámicos, ya sea de los componentes puros, mezclas binarias y ternarias con la finalidad de modelar de mejor manera su separación de fases. Utilizando la ecuación de estado SAFT-γ-Mie se modelan los diagramas con curvas x-x-T tanto para VLLE como para LLLE. Lo observable es que efectivamente puede generar ambos equilibrios trifásicos y a la vez se observa en el primer equilibrio la nula formación de un vapor por debajo del equilibrio binario de menor temperatura a presión atmosférica, por otro lado, el LLLE presenta gran representatividad a la hora de ser modelado con SAFT-γ-Mie con excepción de la fase rica en alcohol que presenta desviaciones poco deseadas.
En otras palabras, se concluye que se puede predecir con gran precisión cada uno de los equilibrios termodinámicos utilizando SAFT-γ-Mie, pero teniendo alta capacidad de mejora usando ecuaciones de estado que se ajusten mediante datos experimentales a las condiciones estudiadas para refinar la predicción en todas sus fases. Aunque en primera instancia, si se carece de información experimental, SAFT-γ-Mie parece ser una excelente alternativa a modo de iniciación. Se recomienda a futuras investigaciones la utilización de SAFT-VR-Mie que podría permitir un mejor ajuste, generar más datos experimentales que actualmente son bastante limitados para esta mezcla ternaria y poder comparar mediante simulación molecular para integrar y tener una mejor visión de este.
In chemical engineering, a deep understanding of multicomponent equilibria is essential, both for synthesizing processes and for process optimization, as it enables the ability to generate different phases, which can become a limiting factor at the moment of considering extraction of pure components. In particular, this work analyzes a butanol/water/hexadecane mixture, which is a more sustainable option in regards of generating energy, but the problem is that it contains water which makes good combustion impossible; therefore, the following problem arises: How can water be separated? By having knowledge of the number of components and the intensive variables than can f ixated, the Gibbs phase rule allows to demonstrate the maximum number of phases that a multicomponent mixture can generate, but it does not verify the exact number of phases. In this context, the idea is to implement equations of state and equilibria, such as SAFT-γ-Mie or the Rashford-Rice mass balance respectively. Whereas the first one is a formulation that decomposes the Helmholtz energy that contains the necessary contributions for predicting the molecules and mixtures behavior. While the second one provides information about the separation of said components. Meanwhile, this work analyzes thermodynamic equilibria, whether of pure components, binary or tertiary mixtures, with the aim of better modeling their phase separation. Using the SAFT-γ-Mie equation of state, the diagrams are modeled with x-x-T curves for both VLLE and LLLE. What can be observed is that it can effectively generate both three-phase equilibria, and at the same time, no vapor formation is observed below the binary equilibrium of lower temperature at atmospheric pressure. On the other hand, the LLLE is highly representative when modeled with SAFT-γ-Mie, except for the alcohol-rich phase which presents undesired deviations. In other words, it can be concluded that each of the thermodynamic equilibria can be predicted with great precision by using SAFT-γ-Mie but leaving room for improvement by using equations of state that can be adjusted through experimental data at the studied conditions to refine the predictions in all its phases. Although at first glance, if experimental data is lacking, SAFT-γ-Mie seems like an excellent alternative as a starting point. For future research it is recommended the use of SAFT-VR-Mie, which could allow a better adjustment, generate more experimental data is limited at the moment for this ternary mixture and enable comparison through molecular simulation to integrate and gain a better understanding of it.
In chemical engineering, a deep understanding of multicomponent equilibria is essential, both for synthesizing processes and for process optimization, as it enables the ability to generate different phases, which can become a limiting factor at the moment of considering extraction of pure components. In particular, this work analyzes a butanol/water/hexadecane mixture, which is a more sustainable option in regards of generating energy, but the problem is that it contains water which makes good combustion impossible; therefore, the following problem arises: How can water be separated? By having knowledge of the number of components and the intensive variables than can f ixated, the Gibbs phase rule allows to demonstrate the maximum number of phases that a multicomponent mixture can generate, but it does not verify the exact number of phases. In this context, the idea is to implement equations of state and equilibria, such as SAFT-γ-Mie or the Rashford-Rice mass balance respectively. Whereas the first one is a formulation that decomposes the Helmholtz energy that contains the necessary contributions for predicting the molecules and mixtures behavior. While the second one provides information about the separation of said components. Meanwhile, this work analyzes thermodynamic equilibria, whether of pure components, binary or tertiary mixtures, with the aim of better modeling their phase separation. Using the SAFT-γ-Mie equation of state, the diagrams are modeled with x-x-T curves for both VLLE and LLLE. What can be observed is that it can effectively generate both three-phase equilibria, and at the same time, no vapor formation is observed below the binary equilibrium of lower temperature at atmospheric pressure. On the other hand, the LLLE is highly representative when modeled with SAFT-γ-Mie, except for the alcohol-rich phase which presents undesired deviations. In other words, it can be concluded that each of the thermodynamic equilibria can be predicted with great precision by using SAFT-γ-Mie but leaving room for improvement by using equations of state that can be adjusted through experimental data at the studied conditions to refine the predictions in all its phases. Although at first glance, if experimental data is lacking, SAFT-γ-Mie seems like an excellent alternative as a starting point. For future research it is recommended the use of SAFT-VR-Mie, which could allow a better adjustment, generate more experimental data is limited at the moment for this ternary mixture and enable comparison through molecular simulation to integrate and gain a better understanding of it.
Description
Tesis presentada para optar al título de Ingeniero/a Civil Químico/a.
Keywords
Equilibrio termodinámico, Energía de la biomasa, Dinámica de fluidos