球形和不规则粗颗粒流化行为相间相互作用实验和CFD模拟研究

Experimental and CFD simulation study on interphase interaction of the fluidization behavior for spherical and irregular coarse particles

流态化技术已广泛应用于选矿过程中粗颗粒(>74μm)的分离和回收。研究表明,流体动力学条件和相间相互作用是颗粒运动的主要影响条件。本文主要研究碰撞系数和阻力模型对液固流化床流体动力学行为的影响。为此,使用欧拉-欧拉方法,在计算中考虑了球形和不规则的粗颗粒;使用Gibilaro、Gidaspow、Huilin-Gidaspou和Syamlal-O’Brien方程获得曳力。此外,利用颗粒体积分数和床层膨胀比的实验数据对提出模型进行了评估。研究了3个恢复系数(0.85、0.90和0.99)和4个镜面系数(0.01、0.10、0.50和0.99)对颗粒流化行为的影响。结果表明,对于球形和不规则颗粒,Gidaspow和Hulin-Gidaspow模型在预测床层膨胀率和颗粒体积分数上与实验数据具有良好的一致性。最后,当恢复系数为0.90且镜面系数为0.10时,模拟结果与实验结果最为接近。研究结果提高了对粗颗粒在液固流态化中行为的认识,为进一步研究三相浮选过程提供有用的信息。

Currently,fluidization techniques have been widely applied to separate and recover coarse particles(>74μm)in mineral processing.Studies show that the main parameters affecting this regard are hydrodynamic conditions and interphase interactions.The main objective is to investigate the influences of collision coefficient and drag models on the hydrodynamic behavior of liquid-solid fluid beds.Eulerian-Eulerian method was used and spherical and irregular coarse particles were considered in calculations.In this regard,Gibilaro,Gidaspow,Huilin-Gidaspow,and Syamlal-O’Brien equations were used to obtain the drag force.Moreover,experimental data of particle volume fraction and fluid bed expansion ratio were employed to evaluate the proposed models.The effects of three restitution coefficients(0.85,0.90 and 0.99)and four specularity coefficients(0.01,0.10,0.50 and 0.99)on fluidization characteristics were studied.The results indicate that for spherical and irregular particles,Gidaspow and Hulin-Gidaspow models have good agreement with experimental data in predicting fluid bed expansion ratio and particle volume fraction.Meanwhile,high prediction accuracy can be achieved when the restitution coefficient is 0.9 and the specularity coefficient is 0.1.The results improve the understanding of coarse particle behavior in liquid-solid fluidization and provide useful information for further investigation of three-phase flotation processes.