带入口加速段的方形分离器内气固两相流动数值模拟

Numerical Simulating the Gas-solid Flow in Square Cyclone With a Curved Inlet

分离器是循环流化床锅炉的核心部件之一,其性能对锅炉的物料平衡、传热等有着重要影响。除运行工况外,结构参数决定着分离器的性能。为了研究结构参数对方形分离器性能的影响,采用雷诺应力模型(RSM)计算了不同结构参数的方形分离器内气相流场。结果表明:方形分离器内除外涡旋与内涡旋等主流外,还存在许多局部的二次流,这些二次流是影响分离器的分离效率的主要因素之一;结构参数的变化对二次流的强度及位置产生影响,进而影响分离器的分离效率。在气相流场的基础上,采用随机轨道模型计算了方形分离器内的颗粒运动轨迹,发现颗粒从入口越低的区域进入分离器,越有利于分离。

Separator is one key part of circulating fluidized bed boiler, and its performance has a crucial effect on the boiler＇s material balance and heat transfer. Besides the operating conditions, separator＇s performance depends on its structure parameters. In order to research on the square cyclone＇s structure parameters influence on its performance, gas flow in square cyclones with different parameters was predicted using Reynold stress model（RSM）. Results show that there is much local secondary flow in square cyclone besides main vortex, such as spiral down-stream near surface and spiral up-steam at central zone. The secondary flow is one of the effect factors on the collection performance of square cyclone. The cyclone geometry size affects on the intensity and the position of the secondary flow, and then affects on the separation efficiency of the cyclone. Based on the gas flow field, the motion traces of particles in the cyclone were predicted using stochastic tracking model. It is found that the particles which enter the cyclone through the lower zone of the entrance are collected more easily than those through higher zone.