卧螺离心机分离PVC的FCPS分析

FCPS Analysis of PVC Separation by Using Decant Centrifuge

采用计算流体动力学(CFD)方法和计算软件FLUENT对分离聚氯乙烯(PVC)的卧式螺旋卸料沉降离心机转鼓内部流场进行数值模拟。通过对转鼓溢流口区域的涡流进行分析,确定溢流口轴向宽度、转鼓内液池深度、分离因数以及悬浮液流量与溢流口最大负径向速度和上浮临界粒度(FCPS)的关系。模拟结果表明:增大溢流口轴向宽度可以有效减小溢流口最大负径向速度,从而颗粒上浮临界粒度减小,可以提高离心机的分离效率;改变转鼓内液池深度对最大负径向速度影响很小,上浮临界粒度变化不大;当增大悬浮液流量和减小分离因数时,最大负径向速度增大,上浮临界粒度增大。模拟方法和结果可以为不同用途和结构的卧螺离心机设计提供更多参考。

The numerical simulation for the flow field in the drum of decanter centrifuge in separating polyvinyl chloride （PVC） was performed by using CFD method and software FLUENT. Based upon the analysis of the vortex in the overflow mouth, the definite relation of the maximum negative radial velocity on the overflow mouth and therefore the floating critical particle size to the overflow mouth axial width, the pool depth of the drum, the centrifugal factor and the feed flow rate was determined. The simulation results showed that with increasing overflow mouth axial width, the maximum negative radial velocity on the overflow mouth and the floating critical particle size presented the trend of becoming smaller. The change in the pool depth of the drum has little effect on the maximum negative radial velocity on the overflow mouth and the floating critical particle size. With increasing feed flow rate and decreasing centrifugal factor, the maximum negative radial velocity on the overflow mouth and the floating critical particle size become gradually larger. The simulation method and results might be considered as a practical effort for structural design of a decanter centrifuge.