Sensitivity of Thermodynamic Model Parameter to the Design of Heterogeneous Reactive Distillation: Amyl Acetate Esterification

熱力學模式參數對三相反應蒸餾設計的靈敏度分析：乙酸戊酯系統

黃士哲(Shih-Ger Huang) ； 余政靖(Cheng-Ching Yu)

《Journal of the Chinese Institute of Chemical Engineers》 34卷3期 (2003/05) Pp. 345-355

https://doi.org/10.6967/JCICE.200305.0345

摘要

近年來結合反應與分離功能的反應性蒸餾製程重新受到重視。本研究的目的在於繼續探討異相反應蒸餾系統(或三相的反應蒸餾系統)。所謂的異相反應蒸餾即為迴流槽中有兩個液相存在，利用分相槽(decanter)可以有效的分離出水相及有機相。以酯化系統來說，通常重醇類的酯化系統，如：乙酸丙酯、乙酸丁酯、乙酸戊酯及丙酸丁酯，是較適合異相的反應蒸餾系統。它們有以下三個共同的特點： (1)有大的兩相區域存在，(2)在兩相區上有一個三成份的最低溫共沸點，(3)所有的液液平衡線(tie line)均指向單一產物(如：塔頂產物，水)因此在判斷一正確的製程時，我們可以由其相的分離情形的最小共沸點座落位置來決定。熱力學模式可以提供相的分佈情形及所有共沸點組成，進而分類出各種典型的兩相區系統。所以在熱力學模式與參數的選擇也變得非常重要，尤其是汽-液-液平衡及最低溫共沸點的正確描述。以乙酸戊酯為例，若在熱力學的描述不符合以上三個特點，則可能得到相當錯誤的程序設計。

並列摘要

Reactive distillation offers an attractive alternative for process intensification, especially for reaction/separation systems. In this work, we continue the effort to explore a specific class of reactive distillations: heterogeneous reactive distillation (or three-phase reactive distillation). By heterogeneous reactive distillation, we mean two-liquid phase exists in the reflux drum and a decanter is employed to separate the aqueous product from the organic reflux. For esterification reactions, propyl acetate, butyl acetate, butyl propionate and amyl acetate are good examples of this type of reactive distillation, because they all share the following characteristics: (1) a large two-liquid zone exists, (2) the minimum boiling azeotrope is located in the two-liquid zone, and (3) all tie lines slop in the direction of high purity product (typically water). Since phase-split description and location of all minimum boiling azeotropes are crucial for correct process description, the selection of thermodynamic models and corresponding binary parameters become important Unlike typical vapor-liquid equilibria (VLE) systems, the model should be able to describe VLLE (vapor-liquid-liquid equilibria) behavior as well as to locate all minimum boiling azeotropes. In an amyl acetate case study, the results clearly indicate that erroneous process designs may result if the thermodynamic model fails to capture the azeotropes or to locate reasonable two-liquid zone.

並列關鍵字

Sensitivity of thermodynamic parameter ； Esterification ； Amyl acetate ； Reactive distillation ； Three-phase reactive distillation