【作者】 郭丽杰；

【导师】 王京刚； 刘家祥；

【作者基本信息】 北京化工大学 ， 环境工程， 2006， 硕士

【摘要】 涡流空气分级机是一种重要的粉体分级设备。分散是分离的前提条件，进入分级机的粉体必须充分分散；分离效果有赖于合理的流场，合理的流场是达到良好分离效果的必要条件。本文对涡流空气分级机的流场特性和物料分散性二方面进行了实验研究与分析。 在物料进入涡流空气分级机前采用了气流预分散装置，通过气流使物料悬浮分散并输送到分级机中。以滑石粉和石灰石粉料为原料进行了分级实验。结果表明，气流预分散后细粉产率、牛顿分级效率增加，切割粒径增大。不同粒度组成的原料气流预分散的效果不同，平均粒径小(＜4μm)的原料其中含有的超细颗粒不易实现气流预分散。 采用激光多普勒测速仪对涡流空气分级机内环形区进行了流场速度测定，首先研究了预分散气流对涡流空气分级机内流场特性的影响，结果表明，预分散气流可以使环形区上部区域轴向速度明显降低，轴向速度沿轴向分布更加均匀，从而使分级机分级性能提高。 环形区四个不同方位的激光多普勒流场测试结果表明，气流由蜗壳进风口进入环形区一周内的速度分布是不均匀的，结果会造成分级粒径不均。这主要是由于涡壳形状、导风叶片的形状、安装角度等因素而造成的。 研究了二种转笼底盘结构A型(开口)、B型(封闭)对环形区流场特性的影响。结果表明，转笼底盘结构是影响流场特性的关键因素之一。B型底盘条件下流场速度分布对分级过程有利。物料分级对比实验与流场测试结果相符。更多还原

【Abstract】 The turbo air classifier is a very important powder classification device. Dispersion is a premium condition that actualizes ideal classification because the material must be dispersed completely before they enter the classifier. Good separation effect depends on the reasonal flow, which is a necessary condition for the classification. In this study, the flow field characteristics and material dispersion in the turbo air classifier were investigated and analyzed.The airflow pre-dispersion equipment was installed in a turbo air classifier before the raw materials were classified. Raw materials were suspended to disperse and conveyed to classifier by pressured airflow. The classification tests of talc and limestone powder were made and the effect of airflow pre-dispersion on classification performance was investigated under different conditions. The results show that output percentage and Newton classification efficiency of fine powder are increased with the increase of dispersion air velocity, and cut size becomes bigger. The superfine particles (<4μm) in the limestone powder of the small mean diameter are not prone to be pre-dispersed.Velocity measurement of the annular region in a turbo air classifier is performed by Laser Doppler Velocimeter (LDV). At first the effect of the pre-dispersion airflow on the flow field characteristics was studied. It is更多还原