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Journal ArticleDOI

Graphical calculation method for minimum reflux ratio in azeotropic distillation

31 Mar 1972-Journal of Chemical Engineering of Japan (The Society of Chemical Engineers, Japan)-Vol. 5, Iss: 1, pp 20-26
TL;DR: In this paper, the rate of net flow and the composition of the net flow for both stripping and rectifying sections can be calculated from the limiting conditions of the separation desired, and the larger of the two values shall be defined as the minimum reflux ratio of the system.
Abstract: In an azeotropic distillation column, the rate of net flow and the composition of net flow for both stripping and rectifying sections can be calculated from the limiting conditions of the separation desired The pinch points are dotted on the radial lines starting from the point of net flow composition by trial and error, and locus of the pinch points are traced on the triangular diagram by the way of connecting the pinch points Each minimum reflux ratio of stripping and rectifying sections can be calculated from the quantitative ratio of vapor and liquid of the operating line passing the point of intersection of locus line and feed line, and the larger of the two values shall be defined as the minimum reflux ratio of the system For example, we illustrate the graphical calculation method for AcOH-H2O-BuOAc system and AcOH-H2O-EtOAc system
Citations
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Journal ArticleDOI
TL;DR: In this article, a suitable entrainer is selected from three candidate acetates through rigorous steady-state simulation of a heterogeneous azeotropic distillation column system, and the overall control strategy of this column system is proposed to hold both bottom and top product specifications in spite of feed rate and feed composition load disturbances.

107 citations

Journal ArticleDOI
TL;DR: The column sequencing problem for heterogeneous azeotropic distillation is investigated in this article, where it is shown that residue curve maps play an important role in interpreting the behavior of these systems.

84 citations

Journal ArticleDOI
TL;DR: A summary of the most important methods for the calculation of the minimum energy requirement of a distillation can be found in this article, where the authors systematically describe the occurrence of pinch zones, which are columns in which at minimum reflux an infinite number of separation stages would be necessary.
Abstract: The minimum energy requirement of a distillation sets a lower, thermodynamically defined operating limit, which is increasingly important in practice due to growing interest in saving energy. During the conceptual design phase this energy information can also be used to quickly compare distillation configurations. This paper gives a summary of the most important methods published to date for the calculation of the minimum energy requirement. Firstly, the occurrence of so-called pinch zones will be systematically described. These are sections of the column in which at minimum reflux an infinite number of separation stages would be necessary. Then exact and approximating solutions of the problems both for ideal and for nonideal mixtures will be discussed. For ideal mixtures a rapid calculation is possible using the well-known Underwood equations, which can also be applied to complex columns (e.g., several feeds and side products, side stream strippers and enrichers). However, strongly nonideal multicomponent mixtures still require time-consuming simulations of columns having large numbers of plates. In such cases serious convergence problems must often be reckoned with. Recent developments aim at avoiding column simulations and at calculating pinch points directly.

65 citations

Journal ArticleDOI
TL;DR: In this paper, the authors measured the Isobaric vapor-liquid equilibrium (VLE) data for acetic acid+water, n-propyl acetate, and acetic acids+iso-butyl acetate using a modified Rose still.

34 citations

Journal ArticleDOI
TL;DR: In this article, an extraction and distillation hybrid process using a novel mixed solvent was proposed for enhancing acetic acid recovery during terephthalic acid production, which was designed, simulated, and optimized for two mixed solvents.
Abstract: An extraction and distillation hybrid process using a novel mixed solvent was proposed for enhancing acetic acid recovery during terephthalic acid production. Feasible hybrid extraction–distillation schemes were designed, simulated, and optimized for two mixed solvents, p-xylene + methyl acetate, and p-xylene + ethyl acetate, based on liquid–liquid equilibrium data for a quaternary system containing methyl acetate or ethyl acetate with p-xylene, acetic acid, and water. A hybrid process using the p-xylene + methyl acetate mixed solvent was found to generate the desired purity of acetic acid with a lower energy consumption and higher product yield than conventional extraction processes. Results showed that the proposed hybrid extraction–distillation process improves the process economics remarkably: the hybrid process using the p-xylene + methyl acetate and p-xylene + ethyl acetate mixed solvent reduced a total annual cost by 14% and 6%, respectively, compared with the conventional hybrid process using the ...

32 citations