Basic Research of a New Classification System using an Almost Rigidly Rotating Flow

我们研究了一种新的湿式离心式分级，该分级采用旋转双壁容器内的几乎刚性旋转的通过流，该容器由壳体和核心组成。因此，我们得到了以下主要结果：1.对Ekman层分级性能的理论考虑(1)我们得到了Ekman层中颗粒轨迹的近似解。(2)当所有尺寸的进料颗粒在芯壁附近均匀进料时，切割尺寸取决于流动的Ekman数和Rossby数(旋转和通过流量)、壁面梯度和曲率以及颗粒的真实相对密度和形状。2.二氧化硅颗粒亚微米分级的实验考虑(1)当Rossby数epsilon_E为8.1*10^&lt时；-3，清晰度指数取决于Ekman数E，当E=6.7*10^；-5&gt；时，清晰度指标值为1.47。(2)切割大小与E^&lt；1.70&gt；成正比，E*6.0*10^；-6&gt；实现亚微米分级。3.粗粒退出连续分级(1)的理论和实验考虑通过对Ekman运输量的理论分析得出，清晰度指数几乎与无提款率情况下一样好。(2)另一方面，当提款率高于K&lt；Ce&gt；时，清晰度指数在取决于Ekman数和Rossby数的临界提款率K&lt；CS&gt；以下也是良好的，但在K&lt；CS&gt；以上则变得非常糟糕。

We have studied a new wet-type centrifugal classification using an almost rigidly rotating through-flow within a rotating doubled-walled container consisting of a housing and a core. Consequently, we have obtained the following main results.1.Theoretical consideration on the classification performance in an Ekman layr(1) We obtained an approximate soluiton of particle trajectories in the Ekman layr.(2) When the feed particles of all sizes are unifomly fed near the core wall, the cut size depends on the Ekman and Rossby numbers of flow (rotation and through-flow rates), the wall gradients and curvatures, and the true relative density and shape of particles, but the sharpness index is independent of these parameters.2.Experimental consideration of sub-micron classification using silica particles(1) When the Rossby number epsilon_E is 8.1*10^<-3>, the sharpness index depends on the Ekman number E,and a high sharpness index value of 1.47 is obtained for E=6.7*10^<-5>.(2) The cut size is propotional to E^<1.70>, and the sub-micron classification is realized for E*6.0*10^<-6>.3.Theoretical and experimental considerations on the withdrawal of coarse particles for application to a continuous classification(1) When the withdrawal rate is below a threshold value K_<CE> obtained by the theoretical analysis of an Ekman transport, the sharpness index is almost as good as in a no-withdrawal case.(2) On the otherhand, when the withdrawal rate is above K_<CE>, the sharpness index is also good below a critical withdrawal rate K_<CS> depending on Ekman and Rossby numbers, but it becomes extremely bad above K_<CS>.