论文部分内容阅读
采用计算颗粒流体力学模型(CPFD),研究了连续进出料条件下,密相区中床料粒径分布及流化风速对床层气固流动结构、颗粒横向运动行为及停留时间的影响.模型尺寸为900 mm×100 mm×1 200 mm.模拟结果显示,床面呈现出左高右低,排渣口上方存在“死区”,随着流化风速的增加,床面高度差及“死区”大小减小,床内颗粒平均停留时间先减小后增大,最后趋于不变,停留时间分布的离散程度增加,床层膨胀度增加,达到一定风速后增加幅度减小.相同风速下,单一粒径与0.3～0.6 mm宽筛分条件下得到的结果基本一致,0.6～1.5mm宽筛分床内得到平均停留时间要大,停留时间分布函数更为集中.“,”Under continuous feeding and discharging conditions,the influence of bed material size distribution and fiuidization velocities on gas-solid two-phase flow structure,lateral motion and residence time of particles were investigated by computation particle fluid dynamics (CPFD) method,which is a discrete element method (DEM).The model size was 900 mm×100 mm×1 200 mm.The results show that the bed height in right side is lower in left side and a dead zone existed above the bottom ash discharging port.With the increase of fluidization velocity,the difference of bed height and the size of dead zone decrease,and the dispersion of residence time distribution increases.The bed expansion also increases with the fluidization velocity,but the increasing extent decreases when the fluidization velocity exceeds a certain limit.However,the average residence time of particles in the bed is non-monotonic,which firstly reduces,then increases and finally unchange.At the same fluidization velocity,the results of mono-size particle essentially are similar to those of multi-size particles ranging from 0.3 mm to 0.6 mm,but for multi-size particles ranging from 0.6 mm to 1.5mm,the average residence time is larger and the residence time distribution is more concentrated.