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The effect of electrostatics on single bubble in fluidized bed and its mechanism analysis
Powder Technology ( IF 5.2 ) Pub Date : 2018-02-01 , DOI: 10.1016/j.powtec.2017.10.052
Zhen Tan , Cai Liang , Junfei Li , Shuzhao Zhang

Abstract Electrostatic charges, which can influence the hydrodynamics of gas-solid flow, play an important role in gas-solid fluidized bed reactors. The performance of a fluidized bed is related to particles motions, while gas-solids contact are majorly governed by its bubble characteristics. Therefore, bubble phenomenon is particularly important in multiphase flow structure. In this work, glass bead are used as bed material particles, single bubble injection experiments are carried out on a two-dimensional Plexiglas bed. Different superficial gas velocities produce different levels of electrostatic magnitude. After a long-time fluidization, the electrical charge density of the particles reaches stable value and is measured by a faraday cup collected to an electrometer, and then, single bubble is injected into the bed. The bubble rise is recorded by means of Digital Image Analysis (DIA) to obtain excellent snapshots of bubble deformation. The results show that, in the high charged system, the aspect ratio gradually decreases as the rising height increases. The simulation of single bubble injection is implemented by Two Fluid Model (TFM), coupled with electrostatic model, to reproduce qualitative trends in the electrostatic field distribution, stress of the particles and particle movement. Numerical simulations interpret the deformation of bubbles from the direction and magnitude of electrostatic forces on particles around bubble.

中文翻译:

静电对流化床单泡的影响及其机理分析

摘要 静电荷会影响气固流动的流体力学,在气固流化床反应器中起着重要作用。流化床的性能与颗粒运动有关,而气固接触主要取决于其气泡特性。因此,气泡现象在多相流结构中尤为重要。本工作以玻璃珠为床料颗粒,在二维有机玻璃床上进行单气泡注射实验。不同的表观气体速度产生不同水平的静电强度。经过长时间的流化,颗粒的电荷密度达到稳定值,由收集到静电计的法拉第杯测量,然后将单个气泡注入床层。气泡上升是通过数字图像分析 (DIA) 记录的,以获得气泡变形的出色快照。结果表明,在高电荷体系中,纵横比随着上升高度的增加而逐渐减小。单气泡注入的模拟采用双流体模型(TFM),结合静电模型,再现静电场分布、颗粒应力和颗粒运动的定性趋势。数值模拟从气泡周围粒子上的静电力的方向和大小来解释气泡的变形。单气泡注入的模拟采用双流体模型(TFM),结合静电模型,再现静电场分布、颗粒应力和颗粒运动的定性趋势。数值模拟从气泡周围粒子上的静电力的方向和大小来解释气泡的变形。单气泡注入的模拟采用双流体模型(TFM),结合静电模型,再现静电场分布、颗粒应力和颗粒运动的定性趋势。数值模拟从气泡周围粒子上的静电力的方向和大小来解释气泡的变形。
更新日期:2018-02-01
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