基于CFD技术的旋风分离器数值模拟研究

Numerical Simulation Study on Cyclone Separator Based on Computational Fluid Dynamics

旋风分离器在石油化工、环保、医药等行业有广泛的应用。研究颗粒在旋风分离器内部的运动状态十分困难,目前常见的方法有实验法、理论分析法以及计算流体力学法(CFD)。通过Ansys Fluent软件,建立数学模型,通过数值计算的方式,对旋风分离器的内部流场以及分离效率进行模拟。流场模拟中选择雷诺应力模型,模拟过程采用欧拉-拉格朗日模型计算颗粒的运动轨迹。模拟结果为:旋风分离器外部流场总体呈现螺旋向下的趋势,内部流场为螺旋向上的趋势,二者在交界面达到切向速度最大(16m/s);固体颗粒的分级效率曲线接近“S”形,存在一段陡升阶段,在10~20μm范围内,颗粒粒径对分离效率存在显著影响;适当地缩短升气管的插入深度可以提高旋风分离器的分离效率,但同时也会增大压降。选用硅胶进行了旋风分离实验,实验与模拟结果一致。

Cyclone separator is widely used in petrochemical,environmental protection,pharmaceutical and other industries.It is very difficult to study the motion state of particles in a cyclone separator.At present,the common methods include experimental method,theoretical analysis method and computational fluid dynamics(CFD).By using Ansys Fluent software,a mathematical model is established,and the internal flow field and separation efficiency of cyclone separator are simulated by numerical calculation.Reynolds stress model is cho-sen in the simulation of flow field,and Euler-Lagrange model is used to calculate the trajectory of particles.The simulation results show that the external flow field of the cyclone separator generally presents a spiral downward trend,while the internal flow field presents a spiral upward trend,and the tangential velocity reaches the maximum(16m/s)at the interface of the cyclone separator.The classification efficiency curve of solid particles is almost S-shaped,with a segment of sharp rise,and the particle size has a significant influence on the separation efficiency in the range of 10~20μm.Properly shortening the insertion depth of the riser can improve the separation efficiency of the cyclone separator,but also increase the pressure drop.Silica gel is used for cyclone separation experiments,and the experimental results are in agreement with the simulation results.