基于分离效率的卧螺离心机CFD分析

从分离效率的角度对卧式螺旋卸料离心机转鼓内的流场进行数值分析.通过剖析推料螺旋与转鼓溢流堰的结构特点可知,转鼓内流体在轴向为薄层流动,在径向由于涡流产生向内流动导致颗粒上浮,这两者对离心机分离效率有决定性的影响.结合CFD数值分析和颗粒的Stokes沉降运动关系,提出将薄层流动与上浮临界粒度应用于离心机分离能力计算的理论和方法.文章通过定义沉降粒度和上浮临界粒度,进一步把分离能力计算与分离效率相关联,使该方法更接近离心机分离工艺的实际情况.通过对工业中典型离心机进行实例计算,证明了该方法的可行性和准确性.

CFD Analysis Based on Separation Rate for Decant Centrifuge

With respect to separation efficiency,the numerical simulation for the flow field in the drum of decanter centrifuge was performed in this article.From the analysis of the structures in conveying screw and the overflow weir,it was known that the fluid in the drum flows in the form of thin layer; in the radial direction the fluid flow inward due to eddy and result in the upward floating of particles; these two phenomena have deterministic effects to the separation efficiency of decanter centrifuge.Combined with CFD numerical analysis and Stokes particle sedimentation relation,the theory and method of applying thin layer flowing and critical floating particle size in the calculation of the separation efficiency of decanter centrifuge were provided.Based on the definition of critical particle sizes for sedimentation and upward floating,the separation capability calculation is correlated with separation efficiency so that the result of this method is more closed to the practical separation process of centrifuge.Finally,through the practical calculation for typical centrifuge used in industry,the feasibility and accuracy of this method have been proved.