【作者】 叶立；

【导师】 黄卫星；

【作者基本信息】 四川大学 ， 化工过程机械， 2003， 硕士

【摘要】 硅橡胶膜生物反应器乙醇发酵技术的开发研究对于发展农产品节约化加工技术、替代石油的新型清洁能源生产和化学原料的低成本制造等具有重大意义。本文对硅橡胶膜生物反应器乙醇发酵系统运行性能进行实验研究，建立了一套有效容积4L，装配膜面积0.024m~2，包括原料处理、产物回收及反应条件控制的新型硅橡胶膜生物反应器系统。直接采用工业酵母进行发酵，测定了各种条件下发酵液及冷凝液的变化，对冷凝系统进行传热、耗能计算，总结出了硅橡胶膜生物反应器乙醇连续发酵过程的基本控制条件，并对系统的操作性能及其应用于实际生产的可行性作出了一定分析。 发酵温度、基质糖浓度对发酵过程均有影响。过高温度(40℃)下酵母细胞生长期短；过低温度(25℃)下细胞代谢缓慢；35℃时细胞生长良好，浓度最高可达16g／l，乙醇产量超过130g／l。过高或过低的基质糖浓度都会对酵母细胞生长产生抑制作用，但由于较高浓度下细胞活性期较长，因而有利于连续发酵过程的进行。 长达350h的连续发酵实验表明，硅橡胶膜的渗透蒸发作用有效消除了产物抑制效应，发酵液中的酵母浓度稳定在14g／l左右，比传统乙醇发酵过程高3倍以上；发酵系统可从浓度8w％的发酵液中直接提取浓度45.2w％的乙醇溶液，有利于降低后继蒸馏操作所需要的能耗。实验所采用的新型硅橡胶复合膜具有优异的分离性能，在分离40℃、5％的乙醇-水溶液时，膜渗透通量＞1500g／m~2．h，分离因子稳定为9.5～10。具有较好的潜在经济效益。 通过对冷凝系统的热力学分析，确定了冷凝控制温度和产品乙醇浓度之间的关系。分析和实验结果表明，控制冷凝温度可改变冷阱收集液中的乙醇浓度，从而得到指定浓度的产品。这不仅对简化食用白酒等生产过程的工艺步骤并提高产品品质有重要启示，同时也对设备设计和过程条件的选择具有参考价值。更多还原

【Abstract】 Technology of ethanol continuous fermentation with a silicone rubber membrane bioreactor has great importance in developing economized agricultural product processing, new petroleum-replaced clean energy production and low cost manufacture of chemical raw materials, etc. Operating functions of silicone rubber membrane bioreactor system are studied in this thesis. A silicone rubber membrane bioreactor system, including raw material treatment, product recovering and operating factors controlling, is assembled in the experiment, in which the reactor’s volume is 4L and the effective membrane area is 0.024m². Through testing variations of broth and condensate under different operating conditions and calculating heat-transfer and energy-consuming in the condensation system, the suitable operating factors for ethanol continuous fermentation are found, and application potential of silicone rubber membrane bioreactor in industry is testified.Both temperature and glucose concentration in substrate have influence on fermentation process. At higher temperature （40℃）, growth periods of yeast cells become shorter, while at lower temperature （25℃）, metabolism of yeast cells become slower; the highest cell concentration is achieved at 35℃ which comes up to 16g/l and the accompanying ethanol concentration in broth is over 130g/l. Yeast cell growth will be inhibited when the glucose concentration in substrate is either too high or too low, but because the cells can survive longer in higher glucose concentration environment, increasing glucose concentration in broth properly will benefit to ethanol continuous fermentation process.The continuous fermentation experiment which last 350 hours shows that the pervaporation character of silicone rubber membrane can eliminate the inhibition effect of production ethanol effectively. Cell concentration in broth keeps at 14g/l around during the long period, over 3 times more than those in conventional fermentation processes. Ethanol solution of 45.2w% can be obtained from 8w% broth directly, which means large amount of energy will be saved for subsequent distillation operations. The silicone rubber membrane in this bioreactor systempossesses excellent separation property. It has a flux of over 1500g/m²-h and a selectivity between 9.5 to 10 when evaporating the 5w% ethanol-water solution at 40 ℃., showing a good potential economy benefit.Through analysis of the condensation system, which based on a simple but accurate thermodynamics model, the relationship between temperature and product concentration is developed. The analysis and experiment show that appointed-concentration products can be obtained simply by controlling condensers’ set-temperatures. This result has an important significance not only for the simplification of drinking ethanol process and the improvement of product quality, but also for the equipment design and process control.更多还原