生物过程中的分立、耦合、并行机制及其在纤维素制酒精中的应用
文献类型：学位论文
| 作者 | 肖炘 |
| 学位类别 | 博士 |
| 答辩日期 | 1999-12 |
| 授予单位 | 中国科学院研究生院 |
| 导师 | 李佐虎 |
| 关键词 | 自然生态循环工程化 分立、耦合、并行 生物过程 纤维素 酒精发醇 核孔膜 |
| 其他题名 | Separation, Coupling and Parallel Mechanism in Bioprocess and Its APPLICATION IN Ethanol Production From Cellulose |
| 学位专业 | 化学工艺 |
| 中文摘要 | 当今为解决人类生存的重大威胁和实现可持续发展的目标，紧迫要求尽快实现自然生态循环工程化，应此背景，就必须要尽可能早地实现，目前尚未实现的，纤维素酒精生物转化的工业化；而转化的高昂成本，是制约其工业化的根本障碍。研究开发高效的转化工艺和工程装备，是突破成本障碍的必然要求。本文就此进行了尝试。从对现有工艺各主要环节的分析入手，结合当代科技的发展成就，本文提出了纤维素生物转化制酒精的分立（S）、耦合（C）、并行（P）系统（简称，纤维素制酒精的SCP系统）。在取得良好实验结果的基础上，以对生物界的考察为起点，提出了本文的理论观点，即SCP机制；并基于系统科学构建了本文的理论体系，即SCP理论体系。由此，又统一和指导了本文对转化工艺的研究，以及对其主要环节之一的酒精发酵，进行的相对独立的工程研究，研制出用于酒精发酵的50L多回路自吸循环生物反应器，和多回器自吸循环生物反应－分离装置，并建立了基于该装置的无水进料SCP酒精发酵法，并获得了良好实验结果。由此可见，本文以突破纤维素酒精生物转化工业化进程中的成本障碍为锁定目标，进行了理论研究和工程实践。1．理论研究 对生物界的考察发现，S、C、P在生物界普遍存在且密不可分，是蕴含于生命活动中的客观规律，因而也是保持生物活性、优化生物过民应遵循的机制，即SCP机制。再结合对SCP机制体性、有机性、边界性、有序性和动态性的认识，推演出一个结论：只有遵循和应用SCP机制去分析、归纳、考察、研究和实践，才是优化生物过程的有效方法；并从理论上为生物过程优化，指明了新的具体的原则（SCP原则，下同）、程序、方法、手段、方向和时空上的构成方式。SCP机制与此结论构成了本文的理论体系（SCP理论体系）。据此展望了生物技术产业工程装备的未来发展，提出了类生命反应系统及类生命反应器的设想。2．工程实践 （1）以SCP理论体系看纤维素制酒精的SCP系统，则后者是前者在多个反应层次（含生物反应和生化反应等）上，进行工程实践的实施例，是以工艺开发为主的实践。由基于核孔膜构成的小实验装置，获得的酒精浓度8.14％(v/v，下同)、发醇速率0.66 g/L/h、纤维素转化率80.1％，分别是对等条件下，同步糖化发酵法（SSF），这一目前主流工艺的1.8、1.3和1.7倍。对于SSF，即便经优化，其酒精浓度也只能再提高到1.1倍，即前者的8.14％仍比优化后的SSF高1.63倍。另外，8.14％也高于国外报道的，由SSF获得的最高酒精浓度7.22%(v/v)。相比于SSF，该系统是转化工艺的又一发展。（2）对酒精发酵进行的的专门研究，是SCP理论体系在单一反应层次上进行工程实践的实施例，是以生物反应器设计为主的工程实践。以“多回路”、“自吸循环”及其组合为主要特征的，可增大反应器开放程度的，多回路自吸循环生物反应－分离装置，使目前最优的酒精发酵水平明显提高。现有工艺的最好结果是，得到了浓度为40～50.5％的酒精解吸液；但低于SCP酒精发酵得到的平均浓度为72.3％的酒精解吸液，与此同时，发酵液酒精浓度则被制控在6.55％以下。显然，SCP酒精发酵有效缓解了酒精发酵中的高能耗，和酒精对酵母的抑制作用，这两大问题，具有工业开发价值。另外，对SCP酒精发酵进行的温度、pH周期刺激显示，前者使其酵母浓度、解吸液平均酒精浓度、葡萄糖消耗速率和酒精生成速率，分别提高了55％、3.8％、38％和35％，但后者无明显作用。表明，一定的外界周期刺激可有效优化SCP酒精发酵。最后，建立了如下统一描述间歇SCP酒精发酵和间歇酒精发酵的动力学模型(K_p = 0即为描述后者的动力学模型)，其各参数均有明确的物理意义。{-dS/dt = 1/Y_(x/s) dX/dt + 1/Y_(p/s) dP/dt + m_xS dX/dt = μ_m(K/K+(1-K_p)P)(1-K_L X/S+K_xX)X dP/dt = v_m(1-(1-K_P)P/P_m)X该模型的主要特点是，是以简单的形式反映酒精发酵的动力学特征和其中的复杂信息。另外，模型值和实验值良好吻合。本文的上述研究，对促进生化工程的发展，和包括纤维素类可再生资源生物转化在内的自然生态循环工程化的实践，可能会有所帮助。 |
| 英文摘要 | Strategic advantages of ethanol as alternative fuel make the bioconversion of cellulose to ethanol a support for the theoretical investigation and experiments been done in this thesis. The study is under the background to ecological recycle industrialization which is now playing more and more important role in resolving the problem threatening human survival while realizing successive development. 1. Theoretical investigation The separation, coupling and parallel (SCP) mechanisms of bioprocess is obtained when a novel process for ethanol production from cellulose based on Simultaneously Saccharification and Fermentation (SSF) has been constructed with disadvantages of the SSF process avoided. With the universality of SCP mechanisms being realized, its concept system is constructed and its properties which are entirety, organic property, boundary property, orderliness and dynamic property are discussed. Then, following SCP mechanisms which is the precondition of obtaining good results in bioprocess intersification is verified theoretically. Thus it is reasonable to conclude that SCP mechanisms may offer the way, principle, process and construction method for bioprocess intensification. With this conclusion and SCP mechanisms, a SCP theory system is set up. Based on this, lifelike bioreactor system should the next equipment for biotechnology industry. 2. Experiments The experiments of bioprocess intensification principle, SCP principle, lay in two levels, multi bioreactions and single bioreaction. The example on multi bioreaction level is the SCP bioconversion system for cellulose to ethanol. The example on single bioreaction level is the multi-loop self-inducing recycle bioreactor-separator and SCP ethanol fermentation. (1) On multi bioreaction level An SCP system for the bioconversion of cellulose to ethanol is advanced on resolving problems is SSF, in which environment requirements by cellulose saccharafication and fermentation are conflict. Then an experimental equipment based on nuclear track membrane is established as well as corresponding method. With the equipment and method the problem in SSF is resolved. The experiment result shows that parameters in ethanol concentration (8.14% v/v), fermentation rate (0.66 g/L/h) and cellulose conversion rate (80.1%) was 1.8, 1.3 and 1.7 times than that of SSF process with the experiment condition. Even thought the process of SSF was optimized, the ethanol concentration was only be improved 10%, and the former is still 1.63 times higher than it. Besides that, the concentration of 8.14%, and the former is still 1.63% times higher than it. Besides that, the concentration of 8.14% is also higher than the highest ethanol concentration ever reported in the previous SSF studies, which was 7.22%. (2) On single bioreaction level a. Equipment construction A 50L multi-loop self-inducing recycle bioreactor and multi-loop self-inducing recycle bioreactor-separator are constructed. THe distinct characters are functions of multi loops and self-inducing recycle and their combination which intensity the bioreactor's open state. b. Application - SCP ethanol fermentation The batch experiment shows that this process is much better than traditional ethanol fermentation. In addition, the stripping liquid with ethanol concentration 71.2% can be obtained directly. Continued experiment shows that the glucose consuming rate and ethanol producing rate are 3.9% and 4% higher than that obtained in previous batch fermentation, and 90.2%和122.6% higher than that of batch ethanol fermentation. c. Process optimization The SCP ethanol fermentation with pH and temperature oscillation are carried out respectively. The results show that with temperature oscillation, the average cell concentration, average ethanol concentration of stripping liquid, glucose consuming rate and ethanol producing rate are 55%, 3.8%, 38% and 35% higher than that of previous continue fermentation process respectively. This shows that SCP theory system and periodic stimulation theory can be combined while practicing in bioreactor design. The study above shows that the the two problems in ethanol fermentation which are ethanol inhibition and high energy consumption can be solved by SCP ethanol fermentation based on multi-loop self-inducing recycle bioreactor-separator. d. Process simulation A kinetics model which can describe both SCP and traditional ethanol batch fermentation is constructed as following: {-dS/dt = 1/Y_(x/s) dX/dt + 1/Y_(p/s) dP/dt + m_xS dX/dt = μ_m(K/K+(1-K_p)P)(1-K_L X/S+K_xX)X dP/dt = v_m(1-(1-K_P)P/P_m)X With all parameters in the model having definite physical meanings, the model stimulates experiment data very well and reflects complicated information and the rule of fermentation process in its simple form. The results obtained in this dissertation contribute to the biochemical engineering development, and are also helpful in promoting the ecological recycle industrialization including the bioconversion of renewable bioresource such as cellulose material. |
| 语种 | 中文 |
| 公开日期 | 2013-09-27 |
| 页码 | 191 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/2003]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 肖炘. 生物过程中的分立、耦合、并行机制及其在纤维素制酒精中的应用[D]. 中国科学院研究生院. 1999. |
入库方式： OAI收割
来源：过程工程研究所
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