- 學位論文
滲透蒸餾濃縮葡萄糖溶液之模擬及實驗探討
A study on simulation and experiment of osmotic distillation with glucose solutions
摘要
濃縮能讓液態食物有更好的穩定性，運用薄膜技術在食品工業界是一項趨勢，而滲透蒸餾具有很大的潛能作為替代之濃縮技術。由於滲透蒸餾在發展上仍有低的通量的問題存在，因此工程應用上以管狀模組之較高有效接觸面積有較大發展潛力。本研究利用Matlab建立管式模組之模擬程式，預估其通量，並分析不同操作參數對通量之影響，另一方面，利用自製之PVDF模組及商業化Liqui-Cel PP中空纖維模組，進行滲透蒸餾葡萄糖溶液之濃縮實驗，探討其通量與濃縮度之變化情形，並與模擬結果進行比較。最後將滲透蒸餾結合薄膜蒸餾，利用模擬預估其通量，來改善滲透蒸餾低通量之問題。 模擬通量與文獻實驗相比，顯示兩者有良好之一致性，以確認所建立之模擬程式的可行性，分析系統內之質傳阻力，約有超過90 %之阻力來自薄膜端，顯示薄膜的性質對其通量扮演主要角色。自組PVDF模組之實驗結果，其葡萄糖濃度在16.8%時，當溫度從25提升至45℃，通量由0.6上升至2.3 kg/m2hr，與模擬之比較，其相對差異值僅約0.5 ~ 2 %。而商業化之PP中空纖維模組有效面積高達1.4m2，其進料10公升之葡萄糖溶液初始濃度10.5 %，經42小時濃縮操作後，濃度提升至60.5 %，其濃縮度約七倍。
關鍵字
滲透蒸餾；葡萄糖溶液並列摘要
Osmotic distillation (OD) recently is considered to be an alternative technology for concentrating liquid foods, which is an isothermal process and can be performed at ambient temperature, being particularly attractive for heat sensitive products. However, OD processes suffer from low flux, which limits their full commercial application. Considering the commercial design to increase membrane area per unit volume and easy to scale-up, hollow fiber modules are more potential for industrial application. In order to establish the basis of its module design, OD with tube-based membrane modules was analyzed experimentally and also gave a comparison with the theoretical simulations. Finally, a preliminary analysis for OD coupled with membrane distillation(MD), called osmotic membrane distillation (OMD), was also studied by simulation. A comparsion between the OD flux simulated in the study and that measured from literatures was made first and showed both have good consistency. The simulated results also indicated that more than 90 % of mass transport resistance in the OD process is contributed from membrane layer. Experiments using the self-assembly PVDF tubular membranes module for feed of 16.8 wt% glucose solution and 45 wt % CaCl2 draw solution showed the fluxes increase from 0.6 to 2.3 kg/m2hr as solution temperature operated in the range from 25 to 45℃. As compare the experimental data with simulation, only 0.5~2 % difference was observed. The simulation also showed that the flux increases about 100 % when the draw solution is maintained at 35℃ while the feed temperature of glucose solution is increased from 35 to 45℃ for the so called OMD processes . Batch experiments for concentrating glucose solution were carried out with 1.4 m2 Liqui-Cel PP module. The feed solution initially of 10.5 wt % glucose and 10 L was concentrated up to 60.5 wt % after 42 hrs operation.