【作者】 李林；

【导师】 张旭斌；

【作者基本信息】 天津大学 ， 化学工程， 2010， 硕士

【摘要】 多相催化过程在化学工业中占有重要地位,传统固定床和浆态床等多相反应器在化工生产中应用广泛,但面临着不容忽视的问题与挑战。新型的整体式反应器具有床层压降低、传质效率高、容易放大和生产强度大等优点,成为替代传统多相反应器的一个有吸引力的选择。尽管具有上述优势,整体式反应器在化工生产中应用还是较少,一个很重要的原因是基础工作很缺乏,特别是流体流动和传质规律的两大核心问题的研究还很不完善和系统,论文对细通道内的流动和传质进行了研究。本文实验研究了整体式多通道内水-CO₂体系的气液传质,测定了液侧体积传质系数。实验结果表明随着表观气速和表观液速的增加,液侧体积传质系数和压力降都变大。采用计算流体力学的方法研究圆形管道内Taylor气泡到液相的传质,使用周期性边界条件和二维轴对称模型,假设Taylor气泡具有理想形状、管内为层流流动,模拟计算液侧体积传质系数,将气液传质分为液膜传质和球体传质两个部分。模拟研究了不同气泡上升速度、弹单元长度、液膜长度、液膜厚度、液相扩散系数和管径对液侧体积传质系数kLa的影响。重点模拟了直径1.068mm的圆形管道,研究了气泡上升速度、弹单元长度、液膜长度和液膜厚度对液膜传质分系数kL,film和（kL,filmafilm）/kLa影响。以Taylor气泡走过一个完整弹单元长需要的时间t为基准,计算最初时间t内的平均液侧体积传质系数,定义为（kLa）0,拟合得到（kLa）0的计算公式,发现（kLa）0与气泡上升速度的0.5次方成正比,与弹单元长度成反比,与液膜长度成正比,与液膜的厚度的0.15次方成反比,与液相扩散系数的0.5次方成正比。更多还原

【Abstract】 Heterogeneous catalysis process plays an important role in the chemical industry. The traditional multi-phase reactors such as the fixed bed and the slurry bed reactor are widely used in the chemical production, but the problems and challenges they faces can not be ignored. The new type of multi-phase reactors, monolithic reactor with lower pressure drop, high rate of mass transfer, easy to enlarge and the higher production strength is an attractive alternative to the traditional reactor. Despite these advantages, the monolithic reactor is of less application in the chemical production. A very important reason is the lack of basic work. Especially the law of fluid flow and mass transfer of the two core issues are far from perfect and systemic. The law of fluid flow and mass transfer in a minichannel was studied in the present work.With the water-CO₂ system in the monolithic multi-channel, gas-liquid mass transfer experiment was made to determine the liquid side volumetric mass transfer coefficient in the present work. It is found that as the superficial gas velocity and superficial liquid velocity increased, the liquid side volumetric mass transfer coefficient and the pressure drop increased. The liquid side volumetric mass transfer coefficient kLa was determined from CFD simulations of Taylor bubbles in circular tube, using periodic boundary conditions, two-dimensional axisymmetric model, ideal shape of Taylor bubble and laminar flow. The mass transfer from the Taylor bubble is the sum of the contributions of the two bubble caps, and the film surrounding the bubble. The separate influences of the bubble rise velocity, unit cell length, film length, film thickness, liquid diffusivity and tube diameter on kLa were investigated. The separate influences of the bubble rise velocity, unit cell length, film length and film thickness on the liquid film mass transfer coefficient kL,film and （kL,filmafilm）/kLa were focused in the tube of 1.068mm diameter. It will take a unit cell a time t to cross the top surface. The average liquid side volumetric mass transfer coefficient within the initial time t was defined as （kLa）0. A calculation of （kLa）0 was fitted. It was found that （kLa）0 is proportional to the bubble rise velocity of the 0.5-th power, inversely proportional to the unit cell length, proportional to the length of liquid film, inversely proportional to the liquid film thickness of the 0.15-th power and proportional to the liquid phase diffusion coefficient of the 0.5-th power.更多还原