【作者】 刘大猛；

【导师】 廖强； 王永忠；

【作者基本信息】 重庆大学 ， 动力工程及工程热物理， 2010， 硕士

【摘要】 当前,能源需求的不断增加,有限储量化石燃料的减少以及燃烧造成的环境污染等问题使本世纪的能源问题面临巨大挑战。光生物制氢技术将太阳能利用、废水处理以及氢能源回收等有机地结合起来,集环境资源化、能源化等优点而具有广阔的应用前景,备受国内外学者的关注。细胞固定化技术与光生物制氢的结合可使单位反应器的产氢率和运行稳定性提高,因此,深入研究固定化细胞光生物制氢反应器内多相流体流动特性、有机物组分传输特性以及光合细菌通过生化反应降解有机物的产氢特性,将为固定化细胞技术在光生物制氢领域的应用奠定理论基础,具有重要的学术价值。本文以两种固定化细胞填充床光生物制氢反应器内的底物降解和产氢特性为研究对象,建立了一个能够完整描述包埋颗粒填充床内气液两相流动、光传递、有机物传输以及光合细菌生化反应的两相混合模型,以及描述固定化生物膜制氢反应器内多相流动与底物降解特性和产氢特性相耦合的两相混合模型,并将计算结果与实验结果进行了对比,获得了较好的吻合度。主要研究内容及结果如下:1)针对包埋细胞颗粒填充床光生物制氢反应器,建立了含生化反应的单个包埋颗粒内质量传输理论模型,并以该颗粒内底物降解产生氢气作为源或汇,分析了反应器内流动特性以及操作参数对底物降解和产氢特性的影响,在此基础上,首次建立了包埋颗粒填充床内两相流动、底物及产物传输的一维稳态气液两相混合模型。2)以包埋颗粒填充床一维两相混合模型为基础,研究了光生物制氢反应器各操作参数及结构参数对填充床内葡萄糖降解效率和产氢速率的影响模型计算结果和实验数据吻合良好。研究结果表明:入射光照强度、溶液pH值及温度主要影响微生物生化反应速率及代谢能力,进而影响微生物底物降解速率及产氢速率;进口底物流量主要影响物质相对传输通量及传质阻力;而填充床结构参数,如孔隙率、颗粒半径以及反应器高度等则通过改变填充床底物及产物的传质面积,进而影响到反应器底物降解特性及产氢特性。3)针对颗粒内微生物、底物溶液及反应器材料对光能的吸收等实际情况,考虑包埋颗粒填充床内光衰减,结合光传递Lambert-Beer定律,建立了能够描述光生物制氢反应器内光分布的传递表达式。以此为基础,建立了包埋颗粒填充床内含生化反应、光衰减、流体流动、底物及产物传输相耦合的二维稳态两相混合模型。模型研究结果表明:在低光照强度下,填充床降解效率和产氢速率随光照强度的增大而增大;沿流体流动方向,底物浓度降低,沿光传递方向,底物浓度增大。产氢率则相反。4)以生物膜填充床光生物制氢反应器为研究对象,将反应器内多孔填充床通道简化为平行平板通道,建立了生物膜内物质传输的生化反应动力学模型。在此基础上,将底物降解及氢气产生处理为质量传递的源或汇,建立了含组分扩散、光生化反应的生物膜多孔填充床内一维稳态气液两相混合模型。模型计算值与实验值基本吻合。结果表明:反应器降解效率和产氢速率随孔隙率的增大而减小;而随着入射光照强度或者溶液pH值的增大,反应器降解效率和产氢速率则均先增大后减小。更多还原

【Abstract】 Currently, due to the continual increase requirement of energy sources , the reduce of finite reserved fossil fuel and the environment pollution brought by fossil fuel burning,etc.,the energy issue will be up against great challenge in 21th century. Photo-biohydrogen production technology, combing solar energy utilizing, waste water biodegradation and hydrogen production, and taking the advantages of environment resource recovery and energy regeneration, thus have abroad applied foreground,and attract a number of foreign and domestic researcher’s attention. The integration of immobilized cells technology with photo-hydrogen production can improve the hydrogen production rate and operating stability of photobioreactor. Therefore, further study on the two-phase behaviors, mass and heat transport characteristics, and photosynthetic bacteria biochemistry reaction properties in immobilized cell packed bed photobioreactor is the theoretical foundation of application of such photo-biohydrogen production technology by photobioreactor, and meanwhile shows great academic values.In our study, we forcus on the theoretical research on the biodegradation and hydrogen production characteristics in two kinds of immobilized cell packed bed photobioreactor for hydrogen production. A new two phase mixture model for completely describing gas-liquid flow, light transfer and biochemical reaction characteristics was established meanwhile, we also aimed at the biofilm photobioreactor, and a two phase mixture model was built for describing fluid flow characteristics coupled with biochemical reaction characteristics.A good agreement between the calculated results using our models and experiments results was obtained. The main research contents and achievements are as follows:1) Aimed at the immobilized cell granules packed bed bioreactor, we established the mass transfer model in immobilized cell granules, in order to study fluid flow characteristics and the influences of operating parameters. Based on these, then. A one dimension steady state two phase mixture model was creatively established for describing the multiphase flow, and substrate and products transfer in immobilized cell granules packed bed.2) Based on the one dimension two-phase mixture model established above, the effect of operating conditions and structure parameters of packed bed on glucose consumption efficiency and HPR were studied theoretically. The model results also revealed that illumination intensity, substrate solution pH value and temperature mainly affected kinetic reaction rate and metabolic ability of photosynthetic bacteria, and further lead to effect on glucose consumption efficiency and HPR. The inlet substrate solution flow rate mainly influenced the mass resistance and mass transfer flux. Moreover, the structure parameters of photobioreactor such as porosity, granule radius and height had influence on the biodegrading characteristics and hydrogen production properties by changing the mass transfer area of substrate and products of packed bed.3) Based on the actual situation such as the light absorption in immobilized granules, bulk solution and organic class separately, we added the influence factors of light attenuation to our model. Then, combined with Lambert-beer law of light transfer theory, the light transfer expression was obtained for describing the light intensity distribution in photobioreactor. Based on the above theory, a two dimension steady state two-phase mixture model was creativity established coupled wth biochemical reaction, light attenuation, gas-liquid flow and substrate and products transfer. The model results showed that in low light intensity, the glucose consumption efficiency and HPR increased with the light intensity increase; the substrate concentration decreased along the fluid flow direction, and increased along the light transfer direction; however, the HPR is reverse.4) Aimed at the biofilm packed bed bioreactor of hydrogen production, the porous packed bed was simplified for a parallel plate channel and then the biochemical reaction dynamics model of substrate transfer in biofilm was established. Base on the above theory, a theoretical model named one dimension steady state two-phase mixture model was creatively built containing species diffusion and biochemical reaction. The results of model ware basically in agreement with the experimental data. The model results also revealed that with the increasment of the illumination intensity or the pH value of substrate solution, the consumption efficiency and the hydrogen production rate increased at first then decreased.更多还原