【作者】 万勋；

【导师】 唐寅；

【作者基本信息】 华东理工大学 ， 生物化工， 2011， 硕士

【摘要】 现代生物技术应用需要大量低成本、高质量的产品。而产品的获得必须以实验室规模的生物过程准确放大到工业级规模为前提。但准确放大往往由于放大效应而难以实现,其中一个主要的表现就是反应器内环境的非均匀分布。因此本文的主要研究方向就是基于反应器内非均匀环境的流体动力学研究。为了消除反应器内的非均匀环境,本文采取了两种研究方式。在200L冷模反应器中,通过将计算流体力学(Computational Fluid Dynamics, CFD)模拟与实际测定相结合,优化得到了八种能够消除反应器内环境梯度,功率消耗较低、气液分散特性较好的气液两相搅拌系统。本文还采用了Scale-down方法,通过构建Scale-down反应器来模拟工业级反应器内的非均匀环境。实验中通过测定Scale-down系统中的混合时间及停留时间分布等流体动力学参数,对系统的流体动力学特性有了初步了解。混合实验结果表明,混合时间受循环流量和PFR形式的影响较大。增大循环流量、PFR部分体积或者采用较小的管径均有利于保持PFR中平推流特性。在数据处理中,通过引入虚拟体积(Vvrit)本文对所得混合时间数据进行拟合,对混合时间特性进行了深入的分析。停留时间分布在验证了系统内存在死区或者返混情况的同时,表明PFR内的流体动力学特性受循环流量和管径的影响较大。但由于PFR体积与系统体积相比较小,所以在停留时间分布测定中表现出PFR部分差异对系统流体动力学特性影响较小的特点。在实验测定的基础上,本文对Scale-down内的流场及流体动力参数进行了CFD模拟验证。模拟结果表明实验中所得数据及结论真实有效,为后期的发酵试验提供了坚实的理论基础。更多还原

【Abstract】 Present biotechnological applications demand large amounts of low-cost and high-quality products. This can only be obtained if processes developed at laboratory scale are accurately translated to full industrial scale. But because of the emergence of scale-up effect, it is likely that conditions in laboratory-scale cultures will differ from those at pilot-plant and production scale. In addition to altering culture variables, changing scales can also affect the degree of homogeneity, with the concomitant appearance of environmental gradients. In this work, two methods were utilized to study fluid dynamics of the Heterogeneities in the reactor.In 200L reactor, Computational Fluid Dynamics (CFD) simulation combined with experiments was utilized to determine the Gas-liquid two-phase impeller system. They could eliminate the degree of homogeneity within the reactor with low power consumption and good Gas-Liquid Dispersion.In this paper, Scale-down method was introduced to simulate the heterogeneities in large-scale bioreactor by constructing Scale-down system. The characteristic parameters of fluid dynamics in Scale-down system, such as mixing time and residence time distribution, were measured to initiate to us in the fluid dynamics character. The results show that tm was mainly influenced by circulation flow and PFR form. Plug flow feature in the PFR was maintained with high circulation flow, large PFR volume and small diameter. Virtual volume (Vvrit) was introduced to analyze the mixing time character. RTD experiments validate the existence of dead zone or backmixing. It was also stated that fluid dynamics character in the PFR was affected by circulation flow and diameter. But influence was reduced when PFR account for a small proportion. Based on experiments, fluid flied and hydrodynamic parameters within Scale-down system were proved by CFD simulation. Our conclusions were validated by simulation results to supply fermentation test with a solid theoretical basis更多还原