Thermodynamic Insights on the Feasibility of Homogeneous Batch Extractive Distillation, 1. Azeotropic Mixtures with a Heavy Entrainer

Abstract

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Thermodynamic Topological Analysis of Extractive Distillation of Maximum Boiling Azeotropes

“…Literature studies on intermediate entrainers or light entrainers validate this assumption (Lelkes et al, 2002;Lang et al, 1999;RodriguezDonis et al, 2012;Shen, 2012;Shen and Gerbaud, 2013b;Laroche et al, 1992). Based on the calculation of the still path and possible composition profiles of the column sections, Lang et al (2000a, b) extended the feasibility of extractive distillation in a batch rectifier for the investigation of the separation of maximum azeotropes, Rodriguez-Donis et al (2009a, 2012a studied the maximum azeotropic mixture separation. However, extractive distillation studies have always considered a heavy entrainer to split a minimum boiling azeotrope which belongs to class 1.0-1a (Knapp and Doherty, 1994a;Luyben, 2008aLuyben, , 2008bBrüggemann and Marquardt, 2004).…”

“…The diagrams of unidistribution lines were used as a main tool for analysis of tangential azeotropes. Recently, Rodriguez-Donis et al, (2009a, 2009b, 2010, 2012a, 2012b) studied how univolatility lines split the composition triangle into regions of a certain order of volatility of components and defined a general feasibility criterion for extractive distillation under an infinite reflux ratio: "Homogeneous extractive distillation of a A-B mixture with entrainer E feeding is feasible if there exists a residue curve connecting E to A or B following a decreasing (a) or increasing (b) temperature direction inside the region where A or B are the most volatile (a) or the heaviest (b) component of the mixture". In this work, we consider unidistribution and univolatility line diagrams for the purpose of sketching the volatility order region and thus of assessing the feasible structures that will obtain possible products and offer information of possible limitations of entrainer feed.…”

Optimal design of extractive distillation for acetic acid dehydration with N-methyl acetamide

“…However, the bottom product from the entrainer recovery column will be the binary maximum azeotrope AA -E having a negative impact over the recovery yield of AA. The variation of the RCM and the map of the extractive liquid profiles for the ternary diagram class 0.0-1 is displayed in Fig.3 when the separation of the components A and B is carried out by a batch extractive distillation column under a feeding of the entrainer in an upper tray of those of the main binary feeding A-B and at finite reflux ratio as it was highlighted out by Rodriguez-Donis et al [22].…”

“…This phenomenon for class 0.0-1 is totally different from that of class 1.0-1a, in which low purity recycled entrainer will prevent the high purity of distillate product A. Following the general feasibility rule published by Rodriguez-Donis et al [22] the reason is that the distillate product is an extractive stable node in class 0.0-1 instead of an extractive saddle node in class 1.0-1a, in which the rectifying section profile will apart from and turn off at the saddle node following the residue curve towards the minimum boiling binary azeotrope. This phenomenon prevents achieving of high purity distillate product.…”

A novel method for detecting and computing univolatility curves in ternary mixtures

“…Particularly, the review paper of Kiva et al (2003) provides a comprehensive historical review of RCMs mainly taking into account the Serafimov's classification of 26 RCM diagrams of ternary systems (Hilmen et al,2002). The important role of RCMs, unidistribution and univolatility manifolds has been well described by Widagdo and Seider (1996), Ji and Liu (2007), Skiborowski et al (2014) for azeotropic distillation process design and by Rodriguez-Donis et al (2009a, 2009b, 2012a, 2012b, Luyben and Chien (2010) and Petlyuk et al (2015) for extractive distillation design purposes. Noteworthy, the existence and the position of the univolatility curve, a particular type of isovolatility curve, determine the component to be drawn as distillate as well as the configuration of the extractive distillation column.…”