矩形截面流化床内颗粒运动可视化试验研究

将高速摄影和颗粒图像测速(PIV)技术结合，以空气作为流化介质，0.1~0.65mm透明玻璃珠为床料，对不同截面风速下矩形截面流化床内过渡区和稀相区的颗粒速度分布进行了分析。试验表明：过渡区截面突变造成颗粒的运动流场发生偏转，颗粒横向运动明显增强；稀相区的出口效应和矩形截面的角落效应对截面上的颗粒速度分布有重要影响。越靠近出口颗粒的横向运动越剧烈。出口效应对颗粒横向速度分量的影响要大于对轴向速度分量的影响，横向速度分量是影响稀相区颗粒宏观运动规律的主要因素。截面风速增大，使得测试区域的颗粒速度分布的不均匀性加剧。为减小锅炉磨损，对截面突变区域要使用圆滑过渡，减少不规则区域的存在；选择合理的出口结构和截面风速，同时要考虑角落防磨。

Visual Measurement of Particle Movement in Rectangular Circulating Fluidized Bed

Particle movement in transition region and dilute region of a cold rectangular circulating fluidized bed (CFB) were studied by using a high-speed video camera and particle image velocimetry (PIV) technology. Measurements were carried out with transparent glass bead between 0.1-0.65mm as bed materials and cold air as flow medium. The results with different superficial gas velocity show that projection section causes the deflexion of particle movement in transition region and increasing particle lateral velocity. Besides, furnace outlet and corner effect has important influence on particle velocity distribution. The closer to the outlet of furnace, the stronger the lateral movement of particles. Outlet effect has more influence on lateral velocity component than axis velocity component. Lateral velocity component is the main factor which affects particle macroscopic motion. With higher superficial gas velocity, the non-homogeneous distribution of particle velocity becomes more acute in research regions. To reduce erosion in CFB boiler, it is recommended to adopt rounding structure in projection section, reduce the existence of irregular region, and select proper outlet structure and reasonable superficial gas velocity, furthermore, corner protection for rectangular CFB is also needed.