硅橡胶膜生物反应器乙醇连续发酵实验及其冷凝系统的能耗分析
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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。
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 0.024m~(2). 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 system
possesses excellent separation property. It has a flux of over 1500g/m~(2)-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.
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。
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 0.024m~(2). 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 system
possesses excellent separation property. It has a flux of over 1500g/m~(2)-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.
引文
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[8] Ghose T K, Bandyopadhyay K K. Modification in physiology and growth of saccharomyces cerevisiae immobilized on different supports[J]. Biotechnol Biochem, 1980,15,7:25-29
[9] Chang Woo Lee, Ho Nam Chang. Kinetics of ethanol fermentations in membrane cell recycle fermentors[J]. Biotechnology and Bioengineering, 1987,29(9):1105-1112
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[12] Chung-Won Cho, Sun-Tak Hwang. Continuous membrane fermentor separator for ethanol fermentation[J]. Journal of Membrane Science, 1991,57:21-42
[13] Denis J O'Brien, Lorie H Roth, Andre J McAioon. Ethanol production by continuous fermentation-pervaporation: a preliminary economic analysis[J]. J Membr Sci, 2000,166:105-111
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[16] Brookes P R, Livingston A G. Mass transfer kinetic properties of silicone membrane by pervaporation[J]. J Membrane Sci, 1990,49:171-205
[17] 李磊，肖泽仪，张志炳，谭淑娟．硅橡胶复合膜用于渗透蒸发的膜传质动力学[J]．化工学报，2002，53(11)：1169-1174
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fermentation[J]. J Memb Sci, 1991,57:21-42
[19] Diog S D, Boam A T, Livingston A G, Stuckey D C. A membrane bioreactor for biotransformations of hydrophobic molecules[J].Biotechnol Bioeng,1998,58:587-594
[20] Livingston A G. A novel membrane bioreactor for detoxifying industrial wastewater: Ⅰ. Biodegradation of Phenol in a synthetically concocted wastewater[J]. Biotechnol Bioeng, 1993,41:915-926.
[21] Livingston A G. A novel membrane bioreactor for detoxifying industrial wastewater: Ⅱ. Biodegradation of 3-chloronitrobenzene in an industrially produced wastewater[J]. Biotechnol Bioeng, 1993,41:927-936.
[22] Brookes P R, Livingston A G. Biological detoxification of a 3-chloronitrobenzene manufacture wastewater in an extractive membrane bioreactor[J]. Waste Res, 1994,28:1347-1354
[23] Brookes P R, Livingston A G. Biotreatment of a point source industrial wastewater arising in 3,4-dichloroaniline manufacture using a membrane bioreactor[J]. Biotechnol Progr, 1994,10:65-75
[24] Lee J Y, Choi Y B, Kim H S. Simultaneous biodegradation of toluene and p-xylene in a novel bioreactor: experimental results and mathematical analysis[J]. Biotechnol Progr, 1993,9:46-53
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[26] Doig S D, Boam A T, Livingston A G. A membrane bioreactor for biotransformations of Hydrophobic Molecules[J]. Biotechnol Bioeng, 1998,58:587-594
[27] Doig S D, Boam A T, Livingston A G. Epoxidation of 1,7-octadiene by pseudomonas oleovorans in a membrane bioreactor[J]. B iotechnol Bioeng, 1999,63: 601-611
[28] Lipiski C, Cote P. The use of pervaporation for the removal of organic contaminants from water[J]. Environ Prog, 1990,9:254—261
[29] 肖泽仪．硅橡胶膜生物反应器及挥发性有机化合物的生物降解[J]．四川大学博士学位论文，2000
[30] 肖泽仪，黄卫星，邢新会等．新型硅橡胶膜生物反应器用于有机废水处理的膜传质动力学[J]．高校化学工程学报，2001，15(1)：71-77
[31] 肖泽仪，关琦，黄卫星等．硅橡胶膜生物反应器降解甲苯的细胞生长动力学[J]．高校化学工程学报，2001，15(6)：557-562
[32] Xiao Zeyi, Zhang Zhibing, Xiao Jian et al. A method evaluation overall mass transfer coefficient of silicone rubber membrane modules used to biodegrade VOCs in wastewater[J]. Proceedings of CKCSST'01, Hangzhou, China Oct. 2001,31-Nov,2: 495-498
[33] Hoover K C, Huang S T. Pervaporation by a continuous membrane column[J]. J Memb Sci, 1982,10:253-261
[34] Porter M C, Michaels A S. Membrane ultrafiltration part 5[J]. Chem
Technol, 1981,1:59-66
[35] Gregory T, Kamalesh P, Sirkar K. Biotechnol[J]. Bioeng Symp,1985,15:621-638
[36] Kyu H, Kyung philip Gerhardt. Extractive ethanol production in a membrane cell recycle reactor[J].J Biotechnol, 1992,24:329-338
[37] Hoffmann H, Kuhlmann W, Meyer H D and Schugerl. Properties of different membranes in continuous ethanol fermentation processing[J]. J Membr Sci, 1989,22:621-628
[38] Shabtai Y, Chaimovitz S, Freeman A, Katchalski-Katzir E, et al. Continuous Ethanol Production by Immobilized Yeast Reactor Coupled with Membrane Pervaporation Unit[J]. Biotechnol Bioeng, 1991,38:869-876
[39] Wolf Hanisch. Cell harvesting in membrane separation in biotechnology[J]. W C,1986,61:589-596
[40] Shin-lchi Nakao, Fumiyo Saitoh, Tomoko Asakura, Kiyoshi Toda and Shoji Kimura. Continuous ethanol extraction by pervaporation from a membrane bioreactor[J]. Journal of Membrane Science, 1987,30:273 — 287
[41] Khorakiwala, K H, Cheryan M, Mehaia M A. Ethanol produteion in a membrane recycle bioreactor: comparison of the performance of saccharomyces cerevisiae and zymomonas mobilis[J].Biotechnol Bioeng, 1991,15:249-253
[42] 钱铭镛．发酵工程最优化控制[M]．江苏科学技术出版社，1998
[43] Cheryan M, Mehaia M A..Membrane bioreactors for high-performance fermentations[J].Process Biochemistry, 1984,22:204-209
[44] Chang Woo Lee, Ho Nam Chang. Hollow fibre bioreactor for ethanol production:application to the conversion of iactose[J].Biotechnol Bioeng,1987,29:1105-1112
[45] 钱铭镛．发酵工程最优化控制[M]．江苏科学技术出版社，1998
[46] 成都科技大学化工原理编写组．化工原理[M]．成都科技大学出版社出版，1991
[47] 尾花英朗[日]．热交换器设计手册[M]．烃加工出版社，1987
[48] 国家医药管理局上海医药设计院．化工工艺设计手册(下册)[M]．北京：化学工业出版社出版，1986
[49] 刘宝菊，吕惠生．我国酒精精馏技术的新进展[J]．酿酒科技，2002，(6)：45-46
[50] 陈鞠声．传统和最新的酒精生产技术[M]．北京：轻工业出版社，1990
[51] 袁庆辉，刘雁然．发酵生产设备[M]．北京：轻工业出版社，1985
[2] 黄宇彤，杜连祥，赵继湘．世界燃料酒精生产形式[J]．酿酒,2001,28(5)：24-26
[3] 黄忠水，纪威，鄂卓茅．我国开发燃料酒精的综合效益分析[J]．节能,2001，(12)：3-6
[4] 无锡轻工业学院，河北轻工业学院．酒精工艺学[M]．北京：中国财政经济出版社，1961．
[5] Cheryan M, Mehaia M A. Membrane Bioreactors[J]. Chemtech, 1986,16(11 ):676-681
[6] Maiorella B, Wilke C R, Blanch H W. Process developments for ethanol production[J]. Adv Biochem Eng,1981,20:43-56
[7] Cheryan M, Mehaia M A. Ethanol production in a membrane recycle bioreactor: conversion of glucose using saccharomyces cerevisiae[J]. Process Biochemistry, 1984,19(6):204-208
[8] Ghose T K, Bandyopadhyay K K. Modification in physiology and growth of saccharomyces cerevisiae immobilized on different supports[J]. Biotechnol Biochem, 1980,15,7:25-29
[9] Chang Woo Lee, Ho Nam Chang. Kinetics of ethanol fermentations in membrane cell recycle fermentors[J]. Biotechnology and Bioengineering, 1987,29(9):1105-1112
[10] Kroner K H, Sehutte H, Hustedt H, Kula M R. Cross-flow filtration in the downstream processing of enzymes[J]. Process Biochemistry,1984,19(2):67-74
[11] Cysewaki G R, Wilke C. R. Rapid ethanol fermentations using vacuum and cell recycle[J]. Biotechnol Bioeng,1977,19:1125-1132
[12] Chung-Won Cho, Sun-Tak Hwang. Continuous membrane fermentor separator for ethanol fermentation[J]. Journal of Membrane Science, 1991,57:21-42
[13] Denis J O'Brien, Lorie H Roth, Andre J McAioon. Ethanol production by continuous fermentation-pervaporation: a preliminary economic analysis[J]. J Membr Sci, 2000,166:105-111
[14] Lau I, Hayward Go Recovery of fatty acids by immobilized solvent extraction[J]. Can J Chem Eng, 1990,68:376-381
[15] Lipiski C, Cote p. The use of pervaporation for the removal of organic contaminants from water[J]. Environ Prog, 1990,9:254-261
[16] Brookes P R, Livingston A G. Mass transfer kinetic properties of silicone membrane by pervaporation[J]. J Membrane Sci, 1990,49:171-205
[17] 李磊，肖泽仪，张志炳，谭淑娟．硅橡胶复合膜用于渗透蒸发的膜传质动力学[J]．化工学报，2002，53(11)：1169-1174
[18] Cho Chung-won, Hwang Sun-tak. Continuous membrane fermentor separator for ethanol
fermentation[J]. J Memb Sci, 1991,57:21-42
[19] Diog S D, Boam A T, Livingston A G, Stuckey D C. A membrane bioreactor for biotransformations of hydrophobic molecules[J].Biotechnol Bioeng,1998,58:587-594
[20] Livingston A G. A novel membrane bioreactor for detoxifying industrial wastewater: Ⅰ. Biodegradation of Phenol in a synthetically concocted wastewater[J]. Biotechnol Bioeng, 1993,41:915-926.
[21] Livingston A G. A novel membrane bioreactor for detoxifying industrial wastewater: Ⅱ. Biodegradation of 3-chloronitrobenzene in an industrially produced wastewater[J]. Biotechnol Bioeng, 1993,41:927-936.
[22] Brookes P R, Livingston A G. Biological detoxification of a 3-chloronitrobenzene manufacture wastewater in an extractive membrane bioreactor[J]. Waste Res, 1994,28:1347-1354
[23] Brookes P R, Livingston A G. Biotreatment of a point source industrial wastewater arising in 3,4-dichloroaniline manufacture using a membrane bioreactor[J]. Biotechnol Progr, 1994,10:65-75
[24] Lee J Y, Choi Y B, Kim H S. Simultaneous biodegradation of toluene and p-xylene in a novel bioreactor: experimental results and mathematical analysis[J]. Biotechnol Progr, 1993,9:46-53
[25] Who W S, Sirkar K K. Membrane handbook[M]. New York: Van Nostrand Reinhold, 1992.
[26] Doig S D, Boam A T, Livingston A G. A membrane bioreactor for biotransformations of Hydrophobic Molecules[J]. Biotechnol Bioeng, 1998,58:587-594
[27] Doig S D, Boam A T, Livingston A G. Epoxidation of 1,7-octadiene by pseudomonas oleovorans in a membrane bioreactor[J]. B iotechnol Bioeng, 1999,63: 601-611
[28] Lipiski C, Cote P. The use of pervaporation for the removal of organic contaminants from water[J]. Environ Prog, 1990,9:254—261
[29] 肖泽仪．硅橡胶膜生物反应器及挥发性有机化合物的生物降解[J]．四川大学博士学位论文，2000
[30] 肖泽仪，黄卫星，邢新会等．新型硅橡胶膜生物反应器用于有机废水处理的膜传质动力学[J]．高校化学工程学报，2001，15(1)：71-77
[31] 肖泽仪，关琦，黄卫星等．硅橡胶膜生物反应器降解甲苯的细胞生长动力学[J]．高校化学工程学报，2001，15(6)：557-562
[32] Xiao Zeyi, Zhang Zhibing, Xiao Jian et al. A method evaluation overall mass transfer coefficient of silicone rubber membrane modules used to biodegrade VOCs in wastewater[J]. Proceedings of CKCSST'01, Hangzhou, China Oct. 2001,31-Nov,2: 495-498
[33] Hoover K C, Huang S T. Pervaporation by a continuous membrane column[J]. J Memb Sci, 1982,10:253-261
[34] Porter M C, Michaels A S. Membrane ultrafiltration part 5[J]. Chem
Technol, 1981,1:59-66
[35] Gregory T, Kamalesh P, Sirkar K. Biotechnol[J]. Bioeng Symp,1985,15:621-638
[36] Kyu H, Kyung philip Gerhardt. Extractive ethanol production in a membrane cell recycle reactor[J].J Biotechnol, 1992,24:329-338
[37] Hoffmann H, Kuhlmann W, Meyer H D and Schugerl. Properties of different membranes in continuous ethanol fermentation processing[J]. J Membr Sci, 1989,22:621-628
[38] Shabtai Y, Chaimovitz S, Freeman A, Katchalski-Katzir E, et al. Continuous Ethanol Production by Immobilized Yeast Reactor Coupled with Membrane Pervaporation Unit[J]. Biotechnol Bioeng, 1991,38:869-876
[39] Wolf Hanisch. Cell harvesting in membrane separation in biotechnology[J]. W C,1986,61:589-596
[40] Shin-lchi Nakao, Fumiyo Saitoh, Tomoko Asakura, Kiyoshi Toda and Shoji Kimura. Continuous ethanol extraction by pervaporation from a membrane bioreactor[J]. Journal of Membrane Science, 1987,30:273 — 287
[41] Khorakiwala, K H, Cheryan M, Mehaia M A. Ethanol produteion in a membrane recycle bioreactor: comparison of the performance of saccharomyces cerevisiae and zymomonas mobilis[J].Biotechnol Bioeng, 1991,15:249-253
[42] 钱铭镛．发酵工程最优化控制[M]．江苏科学技术出版社，1998
[43] Cheryan M, Mehaia M A..Membrane bioreactors for high-performance fermentations[J].Process Biochemistry, 1984,22:204-209
[44] Chang Woo Lee, Ho Nam Chang. Hollow fibre bioreactor for ethanol production:application to the conversion of iactose[J].Biotechnol Bioeng,1987,29:1105-1112
[45] 钱铭镛．发酵工程最优化控制[M]．江苏科学技术出版社，1998
[46] 成都科技大学化工原理编写组．化工原理[M]．成都科技大学出版社出版，1991
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