滲透蒸發分離程序於乙醇-水溶液純化之研究

The study on the purification of ethanol-water mixtures by pervaporation processes.

王俊為(Chun-Wei Wang)

指導教授 ： 何啟東

淡江大學/工學院/化學工程與材料工程學系碩士班/碩士(2011年)

https://doi.org/10.6846/TKU.2011.00467

摘要

由於近年來石油價格飆漲，產業界的經營成本相對提高，連帶影響了民眾在日常生活上的開銷，因此開發可再生的輔助性能源，以減少石化燃料的消耗，是目前科技發展的目標之一。生質酒精是目前主要替代石化汽油的燃料，且必須是重量百分率達99.5%以上的無水酒精，才可按照一定比例和汽油混合，成為替代性的生質燃料。本研究旨在使用滲透蒸發技術去除乙醇水溶液中之水分以改善傳統蒸餾法高能量的需求。本研究探討的滲透蒸發系統分為批次與連續式兩種，使用溶解-擴散模式描述薄膜緻密層的質傳行為，並使用阻力串聯模式，計算出系統總阻力，其中批次滲透蒸發系統之數學模擬部分，本研究推導出對時間及一維的濃度分佈式，而連續式滲透蒸發系統則推導出二維的濃度分佈式，並以有限差分將偏微分方程式簡化成常微分方程式，最後利用四階Runge-Kutta數值方法求解，得到通道內的濃度分佈及理論滲透通量，並與參考文獻之實驗比較。其中，飽和溶液之飽和蒸氣壓在不同溶液組成及溫度下的組成是以UNIversal Functional Activity Coefficient (UNIFAC)法估計。本研究探討在固定進料流體溫度下，不同進料溶液濃度、進料體積流率及滲透蒸發膜材下對滲透通量與濃度極化係數之影響。其結果顯示，滲透通量會隨著進料溶液之酒精濃度增加、進料體積流率上升、薄膜緻密層厚度增加而降低，但進料溶液溫度升高，可提升滲透通量；當進料酒精濃度下降，濃度極化係數會越接近1。

關鍵字

滲透蒸發 ； 濃度極化 ； 脫水 ； 乙醇-水溶液 ； 溶解擴散模式 ； 阻力串聯模式

並列摘要

The mass transport of ethanol solvent dehydration process by using pervaporation (PV) modules has been investigated theoretically. Pervaporation modules were employed instead of the traditional ethanol-solution distillation process which was known as a high energy consuming process. Two operation systems were studied in the present study such as batch and continuous systems. The solution-diffusion model was used to describe the mass transfer behavior in dense membrane layer. Accordingly, the overall mass-transfer resistance from the feed stream to the permeate side was thus calculated with the aid of resistance-in-series model. A mathematical treatment in two-dimensional partial differential equations (PDEs) has been developed by making the differential mass balance in the continuous PV system. The partial differential equations can be transformed into an ordinary differential equations (ODEs) system using finite difference technique and then solved by using the fourth-order Runge-Kutta method. The activity coefficient on ethanol/water mixture were estimated by UNIversal Functional Activity Coefficient (UNIFAC) method to obtain the partial pressure of non-ideal binary mixture for predicting the permeate flux across membrane. The influences of feed solution concentration, feed volumetric flow rate, and membrane material under fixed feed temperature on the mass flux across the membrane were obtained and the concentration polarization phenomena in the feed stream were also discussed.

並列關鍵字

pervaporation ； batch device ； concentration polarization ； dehydration ； ethanol-water mixed solution ； solution-diffusion model ； resistance-in-series model

參考文獻

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