关键词: 粉体技术, 旋风分级器, 流场形态, 数值模拟, 分级性能, 粒度分布

Abstract: The particle classification performance of air classifier mainly depends on the flow field distribution. Two cyclone classifiers were designed which characterized by different air inlet positions. The effect of flow field pattern on particle tracking and classification performance was investigated by using numerical simulation and classification experiments. The results showed that some fine particles were carried into coarse powder by the downward stream near the wall,which aggravates the fine particle entrainment and impairs the classifying accuracy. Two vortexes were formed in the new type cyclone classifier. The upper vortex with 80% of the total air volume moves upward and classifies the fine particles secondarily near the wall,which helps to improving classification efficiency. The downer vortex carries little fine particles,which decrease the particle entrainment in coarse powder. When inlet air velocity varies from 10 m/s to 22m/s,classifying accuracy index increases 27% on average and the pressure drop decrease to 53%-62% compared with the traditional cyclone classifier.

Key words: powder technology, cyclone classifier, flow field pattern, numerical simulation, classification performance, particle size distribution