A Simple Algorithm for Vapor–Liquid–Liquid Equilibrium Computation

Reddy, P. Swapna; Rani, K. Yamuna

doi:10.1021/ie2022064

Cited by 7 publications

(3 citation statements)

References 31 publications

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“…The vapor phase in this work could be considered as the ideal gas because the pressure of the system was always maintained at 101.3 kPa; that is, the activity coefficient and relative volatility could be calculated by the following equations where γ i (or γ j ) is the activity coefficient of component i (or j ), x i (or x j ) and y i (or y j ) represent the mole fractions of components i (or j ) in the liquid phase and vapor phase, respectively, P is the total pressure of the system (about 101.3 kPa), P i s (or P j s ) refers to the saturated vapor pressure of pure component i (or j ) at equilibrium temperature, which could be calculated by the Antoine equation (eq ), and α ij represents the relative volatility of component i to component j . The parameters A , B , and C in the Antoine equation were acquired from the literature and are listed in Table …”

Section: Results and Discussionmentioning

confidence: 99%

Study on the Isobaric Vapor–Liquid Equilibrium Behavior of the Methanol + Methyl Ethyl Ketone System Using Ionic Liquids as Extractants and Model Correlation

Yin

Zhang

et al. 2022

J. Chem. Eng. Data

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In this work, two ionic liquids (ILs), 1-ethyl-3-methylimidazolium bromide ([EMIM][Br]) and 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), were used to separate the mixture of methanol and methyl ethyl ketone. Isobaric vapor–liquid equilibrium data for the binary system of methanol + methyl ethyl ketone and the ternary systems of methanol + methyl ethyl ketone + [EMIM][Br] and methanol + methyl ethyl ketone + [EMIM][DEP] were measured at 101.3 kPa. The results showed that the two ILs could enhance the relative volatility of methyl ethyl ketone to methanol. The more the content of ILs, the greater the relative volatility of methyl ethyl ketone to methanol. The azeotropic phenomenon of the methanol + methyl ethyl ketone system could be eliminated as the content of ILs reached a specific value. The order of separation ability of the two ILs is [EMIM][DEP] > [EMIM][Br]. Finally, the activity coefficient models including the NRTL model and the UNIFAC-Lei model were used to correlate the experimental vapor–liquid equilibrium data, and the correlated results showed that the NRTL model was more suitable to correlate the experimental data.

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Section: Results and Discussionmentioning

confidence: 99%

Study on the Isobaric Vapor–Liquid Equilibrium Behavior of the Methanol + Methyl Ethyl Ketone System Using Ionic Liquids as Extractants and Model Correlation

Yin

Zhang

et al. 2022

J. Chem. Eng. Data

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“…The extractive properties of IL (hydrocarbon distribution ratio and selectivity) along with relative volatility values are critical for gauging the performance of different ILs in the separation of toluene‐1‐heptane mixtures by extractive distillation. The hydrocarbon distribution ratio ( D i ) is given by 46

D_{i} = \frac{x_{i}^{L^{normalI normalI}}}{x_{i}^{L^{I}}},

…”

Section: Methodsmentioning

confidence: 99%

Simplified COSMO‐SAC‐based phase equilibria predictions for extractive distillation of toluene–heptane mixtures using ionic liquids

Bairagya

Kundu

Banerjee

2020

Asia-Pacific J Chem Eng

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A comparative study of isobaric Vapor-Liquid-Liquid Equilibria (VLLE) prediction using the COnductor like Screening MOdel Segment Activity Coefficient (COSMO-SAC) model was performed on nine Ionic Liquids (ILs) and their extractive properties were evaluated for the separation of toluene/1-heptane mixtures using IL-based extractive distillation. For better insights into the IL-hydrocarbon mixture behavior, the ILs were classified on the basis of their constituent cations, i.e. as having imidazolium moiety or pyridinium moiety. A-priori activity coefficient calculation for each phase was performed by the COSMO-SAC method. Compositions of liquid phases were determined by the Liquid-Liquid flash relation of Rachford-Rice and the vapor-phase compositions were obtained by the modified Raoult's Law formulation. Reasonable description of phase behavior of IL-aromatic-aliphatic mixtures was obtained at temperatures 323 K and 363 K. The overall root mean square deviation (rmsd) considering all 104 datasets and 936 data points was found to be 6.83%, which is satisfactory given that our simplified method is also predictive in nature. For ascertaining the robustness of our algorithm, it was compared with the Genetic Algorithm (GA) based GA-NRTL and GA-UNIQUAC models to correlate the experimental VLLE data.

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“…In general, VLLE calculation requires more computational time compared to VLE. To reduce the computational difficulties involved in the simulation for the RBD process, a simple vapor−liquid−liquid-equilibrium (VLLE) method 39 based on iterative computation is used in this study.…”

Section: Composition Estimation For the Rbd Process Using A Reduced O...mentioning

confidence: 99%

Robust Trajectory Tracking in a Reactive Batch Distillation Process using Multirate Nonlinear Internal Model Control

Reddy

Patwardhan

Rani

2019

Ind. Eng. Chem. Res.

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Operating a reactive batch distillation (RBD) process in an optimal manner is of paramount importance for improving product quality and profitability in the face of changing market conditions. However, implementation of an open loop optimal control policy may lead to significant reduction in yield and amount of desired product produced when unmeasured disturbances occur during operation. In this work, an observer error feedback-based multirate nonlinear internal model control (NIMC) scheme is developed for optimal trajectory tracking in the face of unmeasured disturbances. In particular, mismatch in the initial conditions and process parameter variations that can occur during RBD operation are considered. To reduce the time required for online computations, a recently proposed reduced order RBD model [Reddy et al. Compt. Chem. Eng., 2017, 106, 40−56] is used for the controller synthesis. Because the thermodynamic model associated with the RBD process has discontinuities, a multirate version of unscented Kalman filter (UKF) has been developed on the basis of the reduced order model for solving the state estimation problem associated with the proposed NIMC formulation. The efficacy of the proposed approach has been demonstrated by simulating an optimal trajectory tracking problem in the RBD process involving production of butyl acetate. The proposed multirate NIMC formulation is found to be computationally efficient and work reasonably well when tested on the RBD process for solving the set point tracking problem in the presence of unmeasured disturbances. In particular, it is advantageous to operate the RBD process using the proposed UKF-NIMC scheme when the system is subjected to unmeasured disturbances.

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A Simple Algorithm for Vapor–Liquid–Liquid Equilibrium Computation

Cited by 7 publications

References 31 publications

Study on the Isobaric Vapor–Liquid Equilibrium Behavior of the Methanol + Methyl Ethyl Ketone System Using Ionic Liquids as Extractants and Model Correlation

Study on the Isobaric Vapor–Liquid Equilibrium Behavior of the Methanol + Methyl Ethyl Ketone System Using Ionic Liquids as Extractants and Model Correlation

Simplified COSMO‐SAC‐based phase equilibria predictions for extractive distillation of toluene–heptane mixtures using ionic liquids

Robust Trajectory Tracking in a Reactive Batch Distillation Process using Multirate Nonlinear Internal Model Control

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