【作者】 汪丛伟；

【导师】 王树东；

【作者基本信息】 中国科学院研究生院（大连化学物理研究所） ， 化学工程， 2006， 博士

【摘要】 本论文以研发高效的氢源系统为目标,采用实验研究、理论分析和数值模拟相结合的方法对ZNO-CR2O3/CEO2-ZRO2整体催化剂上的甲醇自热重整制氢反应进行了系统的研究,解决了甲醇重整制氢过程中重整催化剂和反应器的优化设计以及放大过程涉及的反应工程问题。通过正交实验系统研究了整体催化剂上甲醇自热重整制氢体系的反应动力学;利用方差分析得出反应温度、空速、水醇摩尔比和氧醇摩尔比都是影响甲醇的转化率、氢产率和CO选择性的重要因素,而且其影响的显著程度依次减弱。采用平板式石英玻璃反应器测试了蜂窝催化剂内的轴向浓度分布,并据此对甲醇自热重整反应的反应路径进行了探讨。结果表明,甲醇水蒸气重整反应在整个催化剂床层上发生,而甲醇完全氧化反应和甲醇分解反应则主要在催化剂床层前段发生。建立了蜂窝反应器内多反应耦合过程的三维数学模型,运用CFD软件对重整器内的温度分布、浓度分布进行了数值计算,模拟与实验结果吻合良好。对蜂窝反应器进行结构优化设计,分析了催化剂长度、高径比、开孔率和载体材质对反应特性的影响,得出此蜂窝反应器最优的结构参数。采用多孔介质模型考察了反应器入口分布方式对75kW重整制氢系统反应效果的影响,并对放大后的反应器内的流场分布进行了数值模拟,结果表明该模型能够比较准确地预测反应器内的场分布。研究了反应器的入口扩张管对反应的影响规律,为反应器的最优化设计提供了理论指导。更多还原

【Abstract】 This paper focused on developing a fuel processing system with high efficiency. The reaction of autothermal reforming of methanol (ATR) over ZnO-Cr2O3/CeO2-ZrO2 monolithic catalyst was investigated by the experimental and theoretical studies. The problems involved in the optimization and scale-up of monolithic catalyst and reactors were discussed.Kinetics of ATR reaction over monolithic catalyst was studied by means of orthogonal experiment. A power-type rate expression was established, and its accuracy was proved by F-examination. Effects of different operating conditions on ATR reaction were investigated by analysis of variance. It was proved that the highly notable influence factors were reaction temperature and space velocity.The concentration profiles of the monolithic catalyst were measured by novel flat-bed reactor and sliced catalyst. The reaction pathways for ATR were discussed according to the results of concentration distribution. It was proved that the steam reforming of methanol happened in the whole parts of the catalyst; whereas the reactions of methanol decomposition and total oxidation of methanol mainly occured in the initial stage of the catalyst.A three-dimensional mathematical model was established to describe the ATR reaction process in monolithic reactor. Distribution of concentration in the reactor had been calculated. Effects of the mole ratio of water/methanol, oxygen/methanol, temperature and gas hourly space velocity (GHSV) on the performance of monolithic reactor had also been simulated by the model. Mathematical simulations of the concentration distribution in monolith reactor were in good agreement with the experiments. The effects of configuration parameters of monolithic reactor on reaction were investigated, such as the length of catalyst, the ratio of height/diameter of catalyst, the porosity of catalyst bed, and even the substrate materials of the catalyst. Optimal design of the monolithic reactor was achieved.The effect of different distributors in 75kW reformer on the performance of ATR system was investigated. Porous media model was chosen to simulate the temperature distribution of the scale-up reactor. The computational results indicate that this model can predict the field distribution of monolithic reactor accurately. The effect of different expanding tubes on reaction performance was also discussed. The result indicates that 120o expanding tube should be chosen preferentially.更多还原