颗粒级配对分级机进料管流动特性影响的数值研究

Effect of particle gradation on flow field of feeding pipe in classifier

为了分析颗粒级配对超细分级机进料管内流动特性的影响,利用计算流体力学(CFD)方法,对进料管内气固两相流动进行研究。在对计算模型进行验证的基础上,揭示了不同颗粒级配下进出口压差、颗粒浓度分布及颗粒分散等特性。研究表明:进料管进出口压差随着级配中大粒径颗粒含量的增加而增加。当级配中小粒径含量较大时,颗粒浓度分布均匀,颗粒分散性较好,入口风速、喂料浓度、颗粒密度的改变对颗粒量纲1浓度分布及分散性影响较小。对于大粒径含量较大的级配,随着入口风速的增加,量纲1浓度减小,浓度分布不均匀度减小,分散性提高;随着喂料浓度的增加,量纲1浓度分布变化较小,但浓度分布不均匀度增大,颗粒分散性下降;随着物料密度的增加,浓度分布不均匀度减小,颗粒分散性提高。竖直段轴向截面上颗粒量纲1平均浓度的高低分界线为一定值(Z=0.5m),且与颗粒级配及操作参数的变化无关。

In order to investigate the effect of particle gradation on the flow field of the feeding pipe in a classifier,the computational fluid dynamics method was applied in the study of gas-solids two-phase flow field in the feeding pipe.After the model was verified,the effects of gas velocity,feeding concentration,particle gradation and density on the pressure difference of inlet and outlet,particle concentration distribution and dispersion were analyzed.The results showed that the pressure difference of inlet and outlet increased with increasing large size particle content of gradation.When gradation was with a high content of small size particle,concentration distribution was uniform and particle dispersion was good.The change of gas velocity,feeding concentration and particle density had less influence on particle dimensionless concentration distribution and dispersion.The operation parameters had significant effects on gradation with a high content of large size particle.With the increase of gas velocity,particle dimensionless concentration decreased,concentration non-uniformity decreased,and particle dispersion became better.With the increase of feeding concentration,concentration non-uniformity increased,and particle dispersion became worse.With the increase of particle density,concentration non-uniformity decreased,and particle dispersion became better.The dividing line between high and low dimensionless average concentration in the vertical section of the axial feeding pipe was Z=0.5 m,and it basically unchanged with the change of particle gradation and operation parameters.