埋管流化床内湿颗粒流动及混合特性的CFD-DEM数值模拟

发布时间：2018-02-10 05:31

本文关键词： 湿颗粒流化迟滞碰撞模型颗粒聚团颗粒混合　出处：《化工进展》2017年06期 　论文类型：期刊论文

【摘要】：掺液滴的气固流化床,越来越多地应用于颗粒材料合成和改性工程,但是液滴使颗粒具有一定的湿度。湿颗粒具有黏性,与干燥颗粒流化特性有很大差异。本文应用迟滞碰撞模型,分别在颗粒碰撞的加载和卸载阶段考虑液体黏弹阻力(lubrication force)和液桥力引起的动能耗损,建立湿颗粒流化床CFD-DEM模型。对含有埋管的湿颗粒流化床进行数值模拟研究,比较了不同黏性条件下颗粒的流动及混合特性。发现随着颗粒黏性的增大,颗粒聚团加剧,气泡边界变得粗糙并逐渐转变为气体沟流,最终导致流化失效,埋管在床中起骨架作用,促进了沟流的形成。随着颗粒黏性的增大,颗粒的相对运动被阻碍,颗粒速度降低,床层压降逐渐减小,颗粒混合速度减慢。
[Abstract]:The gas-solid fluidized bed mixed with droplets is more and more used in particle material synthesis and modification engineering, but droplets make the particles have a certain humidity. In this paper, the hysteretic collision model is used to consider the loss of kinetic energy caused by liquid viscoelastic drag force and liquid-bridge force in loading and unloading stages of particle collision, respectively. The CFD-DEM model of wet particle fluidized bed was established. The numerical simulation of wet particle fluidized bed with buried pipe was carried out, and the characteristics of particle flow and mixing under different viscosity conditions were compared. It was found that the particle agglomeration increased with the increase of particle viscosity. The bubble boundary became rough and gradually changed into gas trench flow, which eventually led to fluidization failure, and the buried pipe played a skeleton role in the bed, which promoted the formation of trench flow. With the increase of particle viscosity, the relative movement of particles was hindered, and the particle velocity decreased. The pressure drop of the bed decreases gradually and the mixing speed of the particles slows down.
【作者单位】：东南大学能源与环境学院能源热转换及其过程测控教育部重点实验室;
【基金】：国家自然科学基金项目(51306035,51676042)
【分类号】：TQ021.1

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