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    Please use this identifier to cite or link to this item: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/76108

    Title: 以複合式薄膜系統分離生質酒精發酵槽產品之最佳化設計
    Other Titles: The Optimum Design of Complex Membrane Systems Used for Separating the Products of Bioethanol Fermentation Broths
    Authors: 黃國楨
    Contributors: 淡江大學化學工程與材料工程學系
    Date: 2011
    Issue Date: 2012-05-02 09:33:38 (UTC+8)
    Abstract: 典型的生質酒精製程中,糖類經由微生物發酵生成酒精。而在發酵之後,生質酒精之濃縮、純化與脫水等下游程序佔有大部分的生產成本。傳統的程序是以離心方式分離酵母菌等大尺寸物質,再進行蒸餾。然而,因為蒸餾所消耗的能源成本較高,如何兼顧產品品質與降低能源消耗便成為未來發展生質酒精的重要挑戰。微生物發酵槽的產物相當複雜,包含微生物細胞、胞外高分子物質、生物碎片、蛋白質、多醣類、鹽類等。故以單一的分離單元進行酒精回收並非有效率的做法,本計畫擬採用複合式薄膜系統分離生質酒精發酵槽之產品,發酵槽中的酵母菌、胞外高分子物質、生物碎片等先以微過濾與超過濾進行回收、分離,未反應的醣類可再連接滲透蒸發等操作單元回收,並獲得純化之生質酒精,預期使用複合式薄膜系統將可提高分離與純化效率、降低生產成本。 本研究為三年期計畫,第一年擬探討生質酒精發酵槽產品之微過濾與超過濾機制。了解不同薄膜之結垢特性,並探討如何善用操作條件控制結垢的型態與目標產物的透過率或選擇率,以提升分離效率。在第二年中,擬探討沉浸式薄膜系統在分離生質酒精發酵槽產品上之優勢。配合多相流之流體力學解析,分析在不同操作條件(例如:懸浮液濃度與黏度、過濾壓差、通氣強度與氣泡形態等)下之流態及濾面剪應力等流體力學特性,了解濾膜之結垢機制與過濾特性,研擬抗薄膜結垢與提高過濾性能的策略,並與第一年的結果比較,分析各種模組之適用時機。在第三年的研究中,除了進行滲透蒸發模組之實驗、分析與設計之外,擬延伸應用前兩年的研究成果,進行包含高效率微過濾與超過濾之複合式薄膜系統設計,探討不同的模組組合與薄膜設計對分離效率之影響。試圖以最經濟、最有效率的複合式安排達成目標產物的分離與純化。並期能在生質酒精的製程中完成模組的最佳化設計。
    In the conventional bio-ethanol production processes, the ethanol in fermentation products was distilled after removing yeast cells and impurities using centrifugal separation. To reduce the energy demand and operation cost in bio-ethanol industries become great challenges in the future development of bio-fuels. Utilizations of membrane separation technology may be a potential application because of energy-saving and high selectivity. The products of bioreactors consist of not only microbial cells but also soluble microbial products and extracellular polymeric substances, which are composed of proteins, carbohydrates, polysaccharides, nucleic acid, lipids, and humic substances. Therefore, to use a single membrane unit is always not an efficient way for separating and purifying the products of bio-ethanol fermentation broths. In this study, complex membrane systems will be designed and optimized for bio-ethanol purification. Yeast cells and macromolecules are recovered or removed using microfiltration and ultrafiltration units. Bio-ethanol will be further concentrated using a membrane pervaporation unit, and the un-reacted sugar will be recovered and recycled back to the fermentation broth. It can be expected that the separation efficiency will be increased and the operation cost will be reduced through the optimum designs. This proposal is a three-year-project and presents a task to attack the technologies involved in membrane separation of bioreactor’s products. In the first year, the mechanisms of microfiltration and ultrafiltration for separating the products of bio-ethanol fermentation broths will be analyzed on a microscopic viewpoint. The effects of operating conditions and membrane properties on the filtration flux, membrane fouling, solute transmissions, and solute selectivity will be discussed by computational fluid dynamic (CFD) method, theoretical analyses and experimental analyses. In the second year, the efforts will be put on the study on the performance of submerged membrane filtration systems. The effects of membrane types and operating conditions, such as concentration and viscosity of suspension, transmembrane pressure, air-sparging intensity, bubble size, etc., on the separation efficiency and membrane fouling will be studied. Various anti-fouling methods, such as periodical backwash, varied transmembrane pressure, etc., on the filtration flux enhancement will be discussed. In the third year, a membrane pervaporation module will be designed, installed and tested. The results obtained in previous years will be extended to design and develop high-performance complex membrane separation systems for bio-ethanol purification. The optimal module designs will be performed through CFD and simulation methods.
    Appears in Collections:[Graduate Institute & Department of Chemical and Materials Engineering] Research Paper

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