EVALUATION OF SCALE-UP CHARACTERISTICS AND DEVELOPMENT OF SIMULATOR FOR MANUFACTURE OF FUNCTIONAL FINE PARTICLES BY GAS - PHASE METHOD

在本研究的实验部分，1。研制了一种装有壁面温度控制器的细颗粒制备反应器，测量了反应器壁面和反应器内部的温度分布。通过数值模拟分析了反应器内的气体速度和温度分布，结果表明，这些分布对反应器内颗粒形成的影响可以从理论上加以评价。制作了一种生成醇化钛蒸气或四氯化钛蒸气的装置，利用该装置将任一种蒸气与载气送入反应器，进行制造二氧化钛细颗粒的实验。利用气溶胶测量技术和电子显微镜测定了颗粒的团聚状态、团聚体和初级颗粒的大小分布。实验阐明了反应温度、载气流速和两种以上不同蒸汽对制备颗粒特性的复杂影响。在理论部分，推导了一个模拟颗粒制造过程的动力学方程，其中考虑了反应产物的过饱和气氛的形成、颗粒从单体通过团簇到颗粒的凝固生长、烧结凝聚颗粒的形态变化以及初级颗粒的生长和颗粒在非等温流场中的输运。本文构建了一种新的二维离散截面模型，通过使用颗粒的表面积和体积来描述团聚颗粒的尺寸和形态的同时变化，从而更准确地预测颗粒形成过程的早期阶段。根据实验结果对所用蒸汽的化学反应速率进行了评估，以将反应速率纳入模型。基于该模型对颗粒制造过程进行了数值模拟，对不同条件下的颗粒尺寸和形貌进行了较好的预测。结果表明，本研究提出的模拟技术可以为颗粒制造反应器的设计和放大提供有用的指导。少

In the experimental portion of this study,1. A reactor equipped with wall temperature controllers for preparation of fine particles was manufactured, and the temperature distribution at the wall and inside of the reactor were measured. Analysis of the gas velocity and temperature distributions in the reactor by numerical simulation showed that these distributions governing particle formation in the reactor could be evaluated theoretically.2. A device for generating titanium alkoxide vapor or titanium tetrachloride vapor was also manufactured, to perform experiments of manufacturing titania fine particles by feeding either of the vapors into the reactor with carrier gas using the device. The state of agglomeration, and the size distributions of agglomerates and primary particles were determined by aerosol measurement techniques and electron microscopy. The complicated changes of the characteristics of manufactured particles with reaction temperature, flow rate of the carrier gas and two … More different vapors were clarified experimentally.In the theoretical portion, a dynamic equation to model the particle manufacturing processes was derived in which formation of supersaturated atmosphere of reaction products, coagulational particle growth from monomers via clusters to particles, morphology change of agglomerated particles by sintering and growth of primary particles and transport of particles in a nonisothermal flow field, were taken into account. Here, a new model called the 2-dimensional discrete-sectional model was constructed to predict the early stage of particle formation processes more accurately by describing the simultaneous change in size and morphology of agglomerated particles using the surface area and volume of the particles. The chemical reaction rates of the vapors used were evaluated from the experimental results to incorporate the reaction rates in the model. Numerical simulation for the particle manufacturing processes based on the model gave good prediction for size and morphology of particles manufactured under various conditions. Consequently, it was made clear that the simulation technique proposed in the present study could give useful guidelines to design and scale-up of particle manufacturing reactors. Less