乳酸乙酯反應蒸餾與薄膜/蒸餾塔混合分離製程之設計與經濟評估

Energy-Efficient Separation Design and Novel Ethyl Lactate Production Process Design using Reactive Distillation and Distillation-Pervaporation Configuration

曹堉暘(Yu-Yang Tsau)

指導教授 ： 陳誠亮

共同指導教授 ： 李豪業(Hao-Yeh Lee)

國立臺灣大學/工學院/化學工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202002536

摘要

本論文提出一種全新的乳酸乙酯商業化製程設計。動力學模型與熱力學模型均採用文獻數據及回歸而成，製程內可分為反應段與分離段，反應段主要由一根反應蒸餾塔構成，用於進行乳酸與乙醇的酯化反應，並在反應蒸餾塔間(第19板)將莫爾濃度0.99的乳酸乙酯產物提出，高沸點的副產物則會從塔底與進料混合回流入塔中，未反應的乙醇與過量的水則會由塔頂流向分離段進一步分離。分離段共有三種組態，分別是(1)先蒸餾塔後薄膜、(2)只用薄膜、與(3)先薄膜後蒸餾塔，薄膜是選用商業化薄膜PERVAP® 2201，其中組態(2)只用薄膜的組態雖然成本最低，但是乙醇進料量卻會增加導致進料成本較高，考量到這點，組態(3)先薄膜後蒸餾塔的成本最低。此組態是先由10個串連的薄膜將乙醇提濃到莫爾濃度0.91，再與乙醇進料混合後回流到反應段。過量的水與少量乙醇則從薄膜的滲透端流向一個較小的蒸餾塔以回收乙醇並排水，以減少乙醇的進料量。
針對第三種組態的最適化，以年總成本為目標函數，分別探討反應蒸餾塔、薄膜與蒸餾塔三者個別的操作參數對於各單元的影響以得到最佳化的組態。另外，乙醇進料方面，雖然進料成本不會被歸類在年總成本中，但由於進料成本也是製程成本的一環，因此本論文也探討純乙醇進料與共沸乙醇進料對於進料成本上的影響。
相較於近期文獻的研究成果，本製程能節省57.9%的年總成本。若採用共沸乙醇進料，則省下的進料成本相當於69.8%的年總成本。

關鍵字

乳酸乙酯 ； 程序設計 ； 反應蒸餾 ； 滲透蒸發 ； 最適化

並列摘要

A novel process for producing ethyl lactate (L1E) is proposed in this study. The rigorous thermodynamic model is verified by experiment data. The overall process can be divided into two parts: the reaction and separation sections. For the reaction section, only one reactive distillation column is used to produce the target product, ethyl lactate, through a sidedraw flow. For the separation section, a new hybrid separation system is composed of membranes in series and one distillation column. The purpose of membranes is to concentrate ethanol to high purity and recycle back to the reaction section., Moreover, one additional column is implemented to recover the loss of ethanol from the permeate of membrane. This hybrid separation arrangement can reduce a lot of energy consumption for ethanol recovery compared with the configuration by using a distillation first then membranes. Finally, ethanol feed concentration is changed from pure ethanol to azeotrope to elucidate its influence on the cost of the whole process. As a result, TAC of this novel process is $211.45×103/y, and 57.9% of TAC reduction is compared to the previous work. The azeotropic ethanol feed can save the raw material cost around 69.8% of TAC to pure ethanol feed case.

並列關鍵字

Ethyl Lactate ； Process design ； Reactive distillation ； Pervaporation ； Optimization

參考文獻

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