Influence of feeding methods on classification performance of powder pneumatic classification and cause analyses
Objective The feeding method is crucial factors influencing the classification performance of the pneumatic classifier.Spiral feed-ing and vibration feeding are popular feeding method for powder preparation.This study aims to comparatively analyze their effects on the classification performance,providing valuable insights for the theoretical guidanceof structural optimization in the pneumatic classifier.Methods In this paper,firstly,the image acquisition of the falling motion of material particles(feeding process)with different feeding methods was carried out using a high-speed camera.TIhe collected images were processed using image processing technology.The influence of feeding methods on powder dispersion was analyzed through image observation and the variation coefficient of the powder distribution area of continuous moments.Then the influence of feeding methods on the classification performance was explored through the CaCO3 powder classification experiments.Results and Discussion According to the image processing results,there are significant differences in the falling state and disper-sion of powder at different feeding methods.Atthe feeding speed of 5 kg/h,the variation coefficients of spiral feeding and vibra-tion feeding are 1.73 and 0.16,respectively.This trend continued at higher feeding speeds,with values forspiral feeding and vibration feeding at the feeding speed of 12 kg/h being 1.38 and 0.15,and at 18 kg/h being 0.90 and 0.12,respectively.Remarkably,the variation coefficient of vibration feeding is smaller than that of spiral feeding at the same feeding speed.Accord-ing to the CaCO3 powder classification experimental results,the vibration feeding is conducive to improving classification perform-ances of the pneumatic classifier,especially under the operating condition with high feeding speed,ascompared to the spiral feed-ing method.At the feeding speed of 18 kg/h,the pneumatic classifier exhibits substantial improvements in classification metrics when utilizing vibration feeding.Specifically,the classification accuracy is improved by 185％,the bypass value is decreased by 75％and the peak on the"fish-hook effect"is reduced by 29％.Moreover,the proportion of ultrafine particles less than 10 μm in the coarse powder is decreased from 11.4％withspiral feeding to 4.4％using vibration feeding.The proportion of fine particles in the coarse powder is greatly reduced,contributing to animprovement in theseparationefficiencybetween coarse particles and fine particles.Conclusion Compared to the spiral feeding method,the vibration feeding method is conducive to improving the classification per-formances of the pneumatic classifier and its classification effects,especially under operatingconditionswith high feeding speed.The vibration feeding method is beneficial to powder disaggregation,which can improve the uniformity and dispersion of powder material feeding compared to the spiral feeding method.The spiral feeding method is not suitable for transporting powder with high viscosity and poor flowability,such as CaCO3 powder,which causes uneven powderdrops during the feeding process and adverselyaffects the dispersion of the feeding.It is the reason that the vibration feeding method can improve the classification accuracy and weaken the"fish-hook"effect.The research results demonstrate that the vibration feeding method has advantages in transporting easily agglomerated powder compared to the spiral feeding method.
万方数据
维普
