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旋流板塔内两相流场的CFD模拟与分析

Simulation and Analysis on the Two-Phase Flow Field in Rotating-Stream-Tray Absorber by Using CFD Method

【作者】 邵雄飞

【导师】 吴忠标;

【作者基本信息】 浙江大学 , 环境工程, 2004, 硕士

【摘要】 旋流板塔(RST)是浙江大学发明的一种高效通用型传质设备,其综合性能优于国外常用的吸收器,作为主设备已成功应用于大中型燃煤工业锅炉的烟气脱硫除尘工程上。旋流塔板上的气液运动是决定塔板效率的主要因素,因此研究气液两相流场将对塔板操作的优化及结构的放大具有重要而现实的指导意义。 本文以商用软件FLUENT为求解软件,拥有双CPU及2G内存的服务器为硬件基础,生成了含有大量网格的Φ150mm和Φ34000mm的旋流板塔的三维模型,用双方程RNG K-ε湍流模型、Eulerian多相流模型和Granular流体模型,对RST内气液运动进行了较为深入的仿真研究。 研究并优化了旋流板塔的绘制方法与网格的生成,为本文模拟所涉及的各种小型、大型及各种板型参数的RST生成了计算所需的三维网格。 用双方程RNG K-ε模型模拟湍流,Eulerian模型模拟气液两相流动,得到了Φ150mm及Φ4000mmRST内一定空塔气速下两相流场的分布及特征,发现RST经放大后液相流场分布的一些问题。 通过改进数学模型,引进Granular流体模型对液体的湍流粘性进行修正,并选用相应的流体-固体交换系数,选用几种特定的液滴粒径,得到了Φ150mm及Φ34000mmRST内更为合理的流场分布结果,发现大型RST内气液流场受液滴粒径影响较大,对较小颗粒(小于300μm)的去除能力较小型RST要低。 本文为RST内两相流场的数值模拟提供了有效的方法,模拟结果有助于旋流板塔的结构优化和放大设计。本文工作也为进一步的研究打下了良好的基础,在RST流场CFD数值模拟的基础上可以进一步进行传热及化学反应过程的CFD数值模拟研究。

【Abstract】 Rotating-stream-tray (RST) absorber, which was invented by Zhejiang University, is a high-efficient equipment for mass transfer. Its performance is better than that of commercial absorbers used in developed countries. It has been successfully implemented in fuel gas desulfurization project for large and medium scale coal-burning boiler. The motion of the gas and liquid phases in RST absorber is the main factor affecting its efficiency. The study of the two-phase velocity field in RST absorber is very important and instructive to the further optimization of RST and the amelioration of operating conditions.Based upon powerful computers and commercially available Computational Fluid Dynamics (CFD) software (FLUENT), 3D models of 0150mm and 04000mm RST with plenty numbers of meshes were generated and the two-phase flow fields in RST absorbers were simulated using Eulerian multiphase theory, two-equation RNG K-e turbulence model and granular flow model in this work.Method for mesh generation of RST was studied and optimized. The computational RST models studied in this paper were strictly build and finely meshed.Two phase flow distribution under certain operating condition in 0150mm and 04000mm RST was obtained by using RNG K-e and Eulerian model. The flow field of RST after amplify was questioned for the distribution of water being abnormal.The model of turbulence viscosity of water phase was improved by adopting granular flow model and the model for interphase exchange coefficient was changed. After setting some characteristic droplet diameters, the new flow fields of 0150mm and 04000mm RST were obtained. It was found that the ability of removing small diameter (less than 300um) droplets of large scale RST was relatively limited.The research carried out in this work provided an effective method for the simulation of two phase flow field in RST. The results are helpful to the structural optimization and large-scale designing. Also, the work provided the foundation for further research. Based on this foundation, the CFD simulation of heat transfer and chemical reaction process in RST can be carried out.

  • 【网络出版投稿人】 浙江大学
  • 【网络出版年期】2004年 04期
  • 【分类号】X701.3
  • 【被引频次】27
  • 【下载频次】893
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