【作者】 许荣强；

【导师】 肖泽仪；

【作者基本信息】 四川大学 ， 化工过程机械， 2004， 硕士

【摘要】 渗透蒸发是近十多年膜分离技术研究最活跃的一个领域,从膜材料、膜过程机理到工程应用都得到迅速发展。渗透蒸发膜分离过程用于均相液体混合物的分离时,对采用传统手段难以处理的恒沸物、近沸点物和共沸物等体系具有特别的优势。对于许多挥发性有机化合物,温度处理过程易导致一些不可逆的化学反应或者是更轻有机组分的挥发,因此使最终得到的产品质量无法得到保证。与传统的分离过程相比较,渗透汽化有许多的优点,它即使在一个温和的过程条件下也有很高的分离效率。本研究中,采用实验室自制的新型硅橡胶复合膜来渗透汽化分离多元有机物-水混合溶液,对模型乙醇-水溶液和实际酿造白酒(多元有机物-水混合溶液)中风味物质的分离性能、过程操作参数对膜分离性能及膜持续运行的稳定性等进行了实验研究和分析。本论文分为以下三个部分:首先,综述了膜分离及渗透蒸发技术的现状、应用和前景;介绍了膜渗透蒸发技术的基本理论及特点。在综合分析国内外发展趋势的基础上,提出本论文的立论依据及研究方案。然后,具体针对渗透蒸发膜及渗透蒸发过程进行理论论述,主要介绍了膜的种类、制造及渗透蒸发膜器,接着,对影响膜分离性能的主要参数进行了逐一论述,并对渗透蒸发过程模型进行了探讨。最后,我们把新型硅橡胶膜运用于多元有机物-水混合溶液的渗透汽化分离进行了研究。首先用新型硅橡胶复合膜分别对52o成品酒及72o基酒中风味物质的进行了分离实验。实验结果发现,新型PDMS复合膜对白酒风味物质具有良好的选择分离性能:原酒中5种酯类(乳酸乙酯除外)和乙缩醛的分离脱除率在<WP=3>86%以上,对高级醇也有良好的分离表现,乙醛的脱除率也超过70%。膜在高浓度的乙醇中能保持良好稳定性,对52o成品酒的平均总渗透通量达到2070 g/(m2·h),平均分离因子(按乙醇-水计算,下同)为4.9; 对72o基酒的平均总渗透通量为2330g/(m2·h),平均分离因子为3.1。 且在高浓度乙醇中膜仍能保持较稳定渗透蒸发性能。渗透酒液感官评价大大好于原酒。接着我们在不同温度下对52o新型白酒进行了渗透蒸发分离实验,研究了温度对分离性能的影响。实验结果表明,5种酯类(乳酸乙酯除外)和乙缩醛的分离脱除率达100%,对高级醇也有良好的分离表现,乙醛的脱除率也超过87%。将分离后的酒液进行重组,得到较原酒品质更高的新酒。膜在高浓度乙醇中能保持良好的稳定性,30℃时,对新型白酒的平均总渗透通量达到2297g/(m2·h),平均分离因子(均按乙醇-水体系计算,下同)为5.22; 35℃时,对新型白酒的平均总渗透通量为2753g/(m2·h),平均分离因子为5.22;40℃时,对新型白酒的平均总渗透通量为3539g/(m2·h),平均分离因子为5.32。通过这些研究,有可能发展一些新的渗透蒸发分离应用技术,如新型白酒勾兑,发酵产物分离回收,白兰地酒生产,天然芳香物质分离,等等。同时也为硅橡胶膜生物反应器发酵生产技术的下一步研究工作提供了一些初步的实验依据和经验。更多还原

【Abstract】 The membrane separation technology has been achieving the rapid progress for the near decades. As one of the newest developments on membrane separation, pervaporation is a promising technique for the separation of liquid mixtures, such as azeotropic and isomeric mixtures, which are difficult or impossible to separate by conventional technology. In many cases, due to volatile feature of the organic compounds, the temperature treatment induces irreversible chemical changes or simple escape of key aromas and therefore, drastically decreases the quality of the final product. Compared to conventional separation processes, pervaporation offers certain advantages; it has high separation efficiency even at mild process conditions. The paper has mainly studied the pervaporation performance of a novel silicone rubber compound membrane in the concoctive aqueous ethanol solution and the Chinese spirits with a membrane bioreactor system (MBR), and the influence of operation parameters on the membrane separation performance. This paper consists of the following three parts:Firstly, a summarized review was done for the present situation, the application and the prospect about the membrane separation and particularly pervaporation technology. The elementary theory and features about the pervaporation technology was introduced. On the basis of this review, a research proposal was presented.Secondly, in accordance with the setup of the MBR and the features of the composite silicone rubber membrane, a principal theoretical analysis was carried out for the pervaporation process. Some details on the membrane materials, structures <WP=5>and forming techniques were analyzed. Then, effects of some process parameters on the membrane separation performance were discussed.Finally, The flavor compositions in 52oand 72o Chinese spirits were separated by pervaporation using a novel plate composite silicone rubber membrane at 30℃ and 1325Pa downstream pressure, respectively. The results suggested that the good separation performance for flavor compositions and the good stability in high ethanol concentration were achieved by the membrane, for example, the separation rate of five kinds of ester (except for Ethyl Lactate ) and acetal in original wine are over 86 %, the membrane also showed a good separation characteristics for fusel, and the separation rate of acetaldehyde is over 70 %. The membrane showed the average total permeation flux in 52o and 72o Chinese spirits were approximately 2070g/m2·h and 2330 g/m2·h, the separation factor for ethanol and water reached the value of 4 .9 and 3.1, respectively. The permeated liquor collected in the downstream membrane tasted much better than the original liquor. Then, in order to learn the influence of temperature on the separation characteristics, the flavor compositions in a new type of 50o Chinese spirits were separated by pervaporation at 30℃ ,35℃and 40℃,1325Pa downstream pressure, respectively. The results suggested that the membrane had excellent separation performance for the flavor compositions and good stability in these liquors with high concentration ethanol, too. For example, separation efficiencies for five kinds of esters (except ethyl Lactate) and acetal in the original liquor are 100%. The membrane also behaved with a good separation for fusel, and removal efficiency over 87 % for acetaldehyde. Recombining the separated spirits, we got the higher quality spirits than original spirits. The membrane had average total permeation fluxes of 2297g/m2·h, 2753 g/m2·h and 3539 g/m2·h and separation factors of 5.22, 5.22 and 5.32 for ethanol-water, with this kind of Chinese spirits, at 30℃, 35℃and 40℃,respectively. <WP=6>Through above a series of studies,it is possible to develop application technology with pervaporation with the composite PDMS membrane, such as for production of good-taste Chinese spirits and Brandy, and for separation of natural aromas and fermenting volatile organic compounds. We also provided some experimental basis and experience for further work of P更多还原