Thermodynamic Insights on the Feasibility of Homogeneous Batch Extractive Distillation, 2. Low-Relative-Volatility Binary Mixtures with a Heavy Entrainer

Abstract

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From batch to continuous extractive distillation using thermodynamic insight: Class 1.0–2 with a heavy entrainer

“…Regarding the distillation of A, there is still a maximum entrainer flowrate at any reflux, above a minimum reflux value occurring because of the happening of a rectifying profile stable separatrix that limits the feasibility [3]. However, continuous mode differs from batch as a there exists a mimimum entrainer flow rate because then feasibility is limited by the stripping profiles region.…”

“…4), infinite reflux analysis shows no limit for the feed ratio. However when the reflux decreases, an unstable extractive separatrix reduces the feasible region (see [3]), thus setting a minimum value for the feed ratio. Batch and continuous modes display the same features.…”

“…In the literature, the continuous mode was investigated for a special case of ternary mixture ABE, class 1.0-1a, where a heavy entrainer is added to separate an azeotropic mixture with minimum azeotrope [1]. The batch method was studied for all 26 classes and found feasibility for classes 1.0-1a, 1.0-1b, 1.0-2, 2.0-1, 2.0-2a, 2.0-2b and 2.0-2c [2][3][4]. We intend to show how information on the feasibility of batch mode could be extended to the feasibility of continuous mode with understanding of limiting values for reflux or feed ratio.…”

Design and control of pressure‐swing distillation for separating ternary systems with three binary minimum azeotropes

“…RCMs are one of the most useful graphical techniques that are often used to assist conceptual design . The analysis of well‐drawn RCMs can provide valuable insights into design feasibility, reveal sensitivity of design options with a visual representation over the whole composition, and help to identify separation constraints.…”

“…To optimally design an efficient pressure‐swing distillation for the separation of ternary nonideal azeotropic mixtures, thermodynamic insights including design feasibility, sensitivity of design options over the whole composition, and separation constraints are first generated through the analysis of well‐drawn residue curve maps (RCMs) . There may exist several distillation boundaries on RCMs, dividing composition spaces into several distillation regions.…”