某350 MW机组循环流化床锅炉颗粒流动特性数值模拟研究

Numerical simulation of particle flow characteristics of a 350 MW CFB boiler

基于计算颗粒流体力学(CPFD)方法,对某超临界350 MW机组循环流化床(CFB)锅炉的颗粒流动特性进行数值模拟研究,主要研究了CFB锅炉内颗粒及颗粒团聚流动特性及其随炉膛高度和操作条件的变化规律,并将模拟结果与现场试验结果进行对比,验证了本次数值模拟的可靠性。结果表明:沿炉膛宽度方向,颗粒轴向运动速度呈现中心区域大、近壁区域小的不均匀分布特点,颗粒质量浓度及团聚物颗粒体积分数则呈现中心区域小、近壁区域大的特点;沿炉膛高度方向,随高度的升高,颗粒质量浓度由140 kg/(m^(2)·s)迅速减小到4 kg/(m^(2)·s),炉膛中心区域颗粒轴向运动较近壁区域增长迅速;循环量的增加和一次流化风速的降低均会使得颗粒轴向运动速度降低,团聚物颗粒体积分数增加。

Based on the computational particle fluid dynamics(CPFD)method,numerical simulation on particle flow characteristics of a 350 MW unit supercritical circulating fluidized bed(CFB)boiler is carried out.The flow characteristics of particles and particle clustering in the CFB boiler and the change laws with the height of the furnace and operating conditions are mainly studied.Moreover,the simulation results are compared with the field test results,which verifies the reliability of the simulation.The results show that,along the width of the furnace,the axial movement speed of the particles presents an uneven distribution of high in central area and low in near-wall area,while the particle mass concentration and particle cluster volume fraction present the characteristics of small in central area and large in near-wall area.Along the furnace height direction,as the height increases,the particle mass concentration rapidly decreases from 140 kg/(m^(2)·s)to 4 kg/(m^(2)·s).The axial movement speed of particles in the center of the furnace increases faster than that in the area near the wall.The increase of the circulation volume and the decrease of the primary fluidization wind speed will reduce the axial movement speed of the particles and increase the volume fraction of the particles cluster.