潮湿细煤气流分级机内气固两相流的CFD模拟

以CFD计算软件FLUENT为平台,采用Realizablek-着湍流模型和欧拉-拉格朗日方法的离散相模型对实验室研制的潮湿细煤气流分级机内的空气流场进行数值模拟,得到分级机中流场的气流速度、流场静压、流场湍动能的分布情况,以及不同粒径细粒煤在分级机中的运动轨迹。数值计算结果表明:分级机内多孔层的设置可造成压强和流速阶跃,增强多孔层上方区域的流速,提升气体对细粒煤的携带作用;导流板的设置使入料口到细料出口间出现了较强的流带,有利于细粒煤分离;导流板和倾斜多孔层的设置使分级机内压差最大且湍流较弱,有利于颗粒分散,实现小颗粒与大颗粒的分离,提高分级效率同时也有利于中等粒径团聚体的破碎、分散,但对大粒径团聚体的分裂破坏作用有限。

CFD simulation of gas-solid two-phase flow in air classifier for moist fine coal

A two-dimensional computational fluid dynamics （CFD） model is developed for the air classifier of laboratory scale using the Realizable k-ε turbulence model and Euler-Lagrange＇s method of discrete phase. Obtain the distribution of airflow velocity, static pressure, turbulent kinetic energy in classifier. Simulate the motion trails of coal particles in different sizes. Simulation results show that setting slant-ranked separation blades can create pressure and flow step in classifier, enhance the flow field above the guide plates and promote coal carrying effect of fluid. The guide plates setting in classifier create a strong flow between the feeding inlet and light products outlet, which is beneficial to coal separation. Guide plates and slant-ranked separation blades in classifier can weaken the turbulence and increase the collisions with coal particles. As moist fine coal feed in classifier, small particles are dragged to the light products outlet by gas flow and big particles fall along the slant-ranked blades to the heavy products outlet by gravity. Collisions can enhance comminuting .and separate the particles in aggregation for the middle size particles. For large size particles or aggregation, collisions are weak.