分離具多共沸物的三成份系統之兩種程序的設計

Two Different Methods for the Separation of Various Ternary Mixture Having Multiple Azeotropes

張尹睿(Yin-Rui Zhang)

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/NTU202101976

摘要

本論文中提出兩種分離具多共沸物之三成分混合物的方法，第一種為利用三成分系統中的液液分相區，使用一分相槽去跨過蒸餾邊界，再透過變壓蒸餾，擴大蒸餾區域進而減少系統內回流量，在此方法中不需引用額外的成分作為夾帶劑增加成分間相對揮發度，也無需使用高壓蒸汽作為再沸器熱源。第二種為利用環氧乙烷與水的反應，用一反應蒸餾塔除去新鮮進料中非主要產物的水，再透過相對揮發度提升圖及成分間的T-xy圖，選乙二醇作為重夾帶劑，使用萃取蒸餾分離剩餘的主要產物，可進一步進行程序整合，將原先的反應蒸餾與萃取蒸餾在同一個單元中進行，藉此省去相關的設備成本與操作成本。
第一種方法選水/異丙醚/異丙醇為例，在此論文中使用一分相槽與三根蒸餾塔，相較於傳統的萃取蒸餾程序，系統內回流量從8596.9 kg/hr減至4667.2 kg/hr，減少了每根蒸餾塔的操作量，此外透過加裝熱交換器及執行熱整合等節能策略，最後所提出之程序可節省33.0%的操作成本及23.0%的年度總成本。此程序也選做進一步的動態模擬討論，透過開環與閉環敏感度分析，固定C1塔回流比，在C1塔及C2塔使用單點溫度控制，在C3塔使用雙點溫度控制，因而提出兩種控制架構，結果顯示兩種控制架構皆可有效地處理四種成分擾動及10%的新鮮進料流量擾動。
第二種方法選水/乙醇/叔丁醇、水/乙醇/四氫呋喃及水/異丙醇/乙腈系統為例，在此論文中先提出三塔複合式反應萃取蒸餾，因為在反應蒸餾塔中，水已經由環氧乙烷反應除去，因此所需填加的重夾帶劑量變少，進而在溶劑回收塔中所需再沸器熱負荷也會降低，此程序可進行程序強化，將反應蒸餾與萃取蒸餾塔合併，再透過加裝熱交換器等節能策略，最終提出之程序的節能效果皆顯著。

關鍵字

三成分含水系統分離 ； 多共沸物組成 ； 液-液分相 ； 變壓蒸餾 ； 反應蒸餾 ； 萃取蒸餾 ； 程序設計 ； 程序控制

並列摘要

In this paper, two alternative method to separate ternary mixture containing water with multiple azeotropes are proposed. First, aided by the liquid-liquid separation, one decanter is used to get cross the distillation boundary. Then, with the help of the pressure sensitive property, it’s feasible to expand the distillation region by increasing the pressure so that the recycle stream in the system can be reduced. The advantage of this method are as follows. First, there is no need for adding a foreign component into the system. Second, high pressure steam won’t be used as heat source for reboiler, for it’s much more expensive.
Water, diisopropyl ether and isopropyl alcohol is chosen as an example for the first method. One decanter and three distillation columns are used. Compared with the conventional extractive distillation, the flow rate of recycle stream decreases from 8596.9 kg/hr to 4667.2 kg/h. Besides, by installing feed effluent heat exchanger and applying heat integration, the final proposed flowsheet can save up to 33.0 % in operating cost and 23.0 % in total annual cost, and this design flowsheet is chosen for further dynamic simulation by open-loop and close-loop analysis, the reflux ratio of column 1 is fixed, and single temperature control is used in column 1 and 2. Then, aided by singular value decomposition, double temperature control is used in column 3. Finally, two control schemes are proposed, and the results show that these two control schemes both can handle the composition disturbance and throughput disturbance well.
Water/ethanol/terbutyl alcohol、water/ethanol/tetrahydrofuran and water/isopropyl alcohol/acetonitrile are chosen as example for the second method. In this paper, triple column reactive extractive distillation is proposed. In the reactive distillation column, most of water is removed by the ethylene oxide dehydration reaction. Then, the amount of heavy entrainer is reduced, and the reboiler duty in the solvent recovery column is also reduced. Process intensification is considered, and the combination of extractive distillation and reaction distillation is used. Moreover, the installation of feed effluent heat exchanger is also used. The final proposed design flowsheet can save greatly in operating cost and total annual cost in all these three example.

並列關鍵字

ternary system containing water ； multiple azeotrope ； liquid-liquid separation ； pressure-swing distillation ； reaction distillation ； extractive distillation ； process design ； process control

參考文獻

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