折流式超重力旋转床流体动力学特性研究

发布时间：2018-06-13 04:42

本文选题：折流式旋转床 + CFD　；参考：《浙江工业大学》2016年硕士论文

【摘要】：折流式旋转床是一种新型的高效气液接触装置,它以离心力场代替重力场,极大的增大了传质比表面积,从而增加了传质效率。本文通过建立装置的二维、三维模型,利用CFD方法对装置内的气液流动状况、压力分布情况等进行研究,并与实验测试结果进行对比验证,可为装置结构改进提供参考。本文主要研究内容及研究结果如下所示:(1)成功将FLUENT引入折流式旋转床的研究工作中,极大地缩短了研究进程;首次对装置全尺寸展开二维、三维模拟工作。模拟结果与实验结果相互对比验证,平均误差在10%以内,模拟结果较好;(2)装置内气体流动状况。气流主要以切向速度为主(占80%以上),由转子外缘向内部流动过程中,气速逐渐降低,这主要是由拐弯处的摩擦阻力引起的;在转子外缘存在较大的速度梯度,易造成能量损失;液体在装置内主要是以液膜、液滴的形式存在,极大的增大了传质比表面积,并且液体的加入使得静圈下隙和气体出口处的漩涡明显减小;不论是气相流动还是液相流动,都受进气量、进液量、转速以及装置结构的影响;(3)装置内压降分布情况。压降绝大多数是由转子处压降贡献的,转子压降随进气量、进液量、转速的增加而增大,转速的增加会使得液滴数量增大,利于传质进行;进气量的增大易造成转子内气速较大,使得装置内持液量增大,转子内液滴被吹出转子,造成雾沫夹带;而进液量的增加会使得流道变得更窄,气速随之增加,也会造成持液量增加和雾沫夹带,因此也不利于传质进行;(4)结构改进。通过模拟发现,在操作工况下,装置内漩涡可以通过加装导流板的形式削减,倾斜气体进口比垂直进口更有利于气体进入转子,减小转子外缘处的速度,较小能量损失。本文研究了折流式旋转床的流动状态、压降分布状况,为弄清装置传质机理,进而改进装置结构、提高传质性能提供参考。
[Abstract]:The baffled rotating bed is a new type of high efficiency gas-liquid contact device, which uses centrifugal force field instead of gravity field, which greatly increases the specific surface area of mass transfer and thus increases the mass transfer efficiency. In this paper, the two-dimensional and three-dimensional models of the device are established, and the gas-liquid flow and pressure distribution in the device are studied by CFD method, and the results are compared with the experimental results, which can provide a reference for the improvement of the device structure. In this paper, the main research contents and results are as follows: 1) fluent is successfully introduced into the research work of the baffled rotating bed, which greatly shortens the research process. For the first time, 2D and 3D simulation work on the full scale of the device is carried out. Compared with the experimental results, the average error is less than 10%. The simulation results show that the gas flow in the device is better. The main flow velocity is tangential velocity (more than 80%). During the flow from the outer edge of the rotor to the inside, the gas velocity decreases gradually, which is mainly caused by the friction resistance at the corner, and there is a large velocity gradient on the outer edge of the rotor. The liquid exists mainly in the form of liquid film and droplet, which greatly increases the specific surface area of mass transfer, and the vortex at the bottom of the static circle and the exit of the gas decreases obviously with the addition of liquid. The pressure drop distribution in the device is affected by the air intake, liquid intake, rotational speed and the structure of the device, regardless of the gas or liquid phase flow. Most of the pressure drop is contributed by the rotor pressure drop, the rotor pressure drop increases with the increase of air intake, liquid intake and rotational speed, and the increase of rotational speed will increase the number of droplets, which is conducive to mass transfer. The increase of air intake will easily result in a larger gas velocity in the rotor, which will increase the liquid holdup in the device, and the droplets in the rotor will be blown out of the rotor, resulting in entrainment of mist foam; and the increase in the intake volume will make the flow channel narrower and the gas velocity will increase. It also leads to the increase of liquid holding capacity and entrainment of aerosol, which is not conducive to the improvement of mass transfer. It is found by simulation that the swirl in the device can be reduced by adding a guide plate under the operating conditions, and the inlet of inclined gas is more favorable to the entry of gas into the rotor than the vertical inlet, and the velocity at the outer edge of the rotor is reduced, and the energy loss is smaller. In this paper, the flow state and pressure drop distribution of the baffled rotating bed are studied, which provides a reference for clarifying the mass transfer mechanism of the device, improving the device structure and improving the mass transfer performance.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ051.1

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