分離異丙醇及乙酸異丙酯的萃取蒸餾程序之節能製程設計與控制

Energy-efficient Separation Design of Isopropyl Alcohol and Isopropyl Acetate Via Extractive Distillation

李亭毅(Ting-Yi Lee)

指導教授 ： 錢義隆

國立臺灣大學/工學院/化學工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202102257

摘要

萃取蒸餾(extractive distillation system)為一用來分離近沸物或共沸物常見的方法，大部分文獻都是探討含最低共沸溫度之混合物的分離。萃取蒸餾法的分離方式，為添加重萃取劑 (entrainer) 進入近沸或共沸物質系統以提升相對揮發度 (relative volatility)，進而使混合物得以分離之方法。
本研究探討之系統為異丙醇與乙酸異丙酯分離，萃取蒸餾系統的設計流程包含兩座蒸餾塔，分別為萃取蒸餾塔與萃取劑回收塔。將欲分離之混合物物注入萃取蒸餾塔，隨著萃取劑的添加，異丙醇對乙酸異丙酯之相對揮發度將會提升，因此異丙醇可以由萃取蒸餾塔之塔頂提出，萃取劑與乙酸異丙酯則由塔底流出；塔底出流進入第二支塔 (萃取劑回收塔)，萃取劑可以藉由萃取劑回收塔純化，成為塔底出流並回流至萃取蒸餾塔重複使用，乙酸異丙酯則可由萃取劑回收塔之塔頂提出。
本文探討四種分離異丙醇/乙酸異丙酯之節能設計流程，包括傳統雙塔萃取蒸餾、熱整合之萃取蒸餾系統、側流萃取蒸餾系統以及隔牆塔萃取蒸餾系統。在產物純度都相同的前提下比較年度總成本(TAC)，選擇最低者進行動態模擬與控制，以確認在進料組成干擾或是流率干擾的情形下，本文提出之控制策略仍能維持高純度之產品規格。

關鍵字

萃取蒸餾 ； 隔牆塔 ； 程序設計 ； 程序控制

並列摘要

Extractive distillation is a common techique for separating close boiling and azeotropic mixtures. especially for. minimum boiling azeotropic mixtures. Usually a heavy entrainer will be introduced into the system to enhance the relative volatility of the mixture in a process based on extractive distillation.
In this thesis, the system discussed is the separation of isopropanol and isopropyl acetate. The design process of the extractive distillation system includes two distillation columns, namely an extractive distillation column and an entrainer recovery column. With the addition of the entrainer, the relative volatility of isopropanol to isopropyl acetate will increase, so purified isopropanol can be extracted from the top of the extractive distillation column. The entrainer and Isopropyl acetate will flow out from the bottom of the column; the bottom effluent enters entrainer recovery column, and the entrainer can be purified and return to the extractive distillation column for reuse.Purified isopropyl acetate can be extracted from the top of the entrainer recovery column.
This thesis discusses four kinds of energy-saving design processes for separating isopropanol/isopropyl acetate, including conventional extractive distillation, heat-integrated extractive distillation system, side-stream extractive distillation system, and extractive dividing wall column system. Under the same product purity conditions, total annual cost (TAC) of each process is calculated. The process with the lowest TAC is then chosen for dynamic control simulation to confirm that the control strategy proposed in this article can maintain high product purity specifications when there are feed composition disturbance and feed flow rate disturbance in the system.

並列關鍵字

Extractive distillation ； minimum boiling azeotrope ； heavy entrainer ； process design ； process control

參考文獻

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