YU Yuan^a, LIU Kerun^a, LIU Xiaoyong^a, LIU Jiaxiang^b, JIAO Zhiwei^a, FU Junjie^a

(a. College of Mechanical and Electrical Engineering,b. Beijing Key Laboratory of Materials Electrochemical Process and Technology,Beijing University of Chemical Technology, Beijing 100029, China)

Abstract

Objective The feeding method is crucial factors influencing the classification performance of the pneumatic classifier. Spiral feeding 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. The 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 dispersion of powder at different feeding methods. Atthe feeding speed of 5 kg / h, the variation coefficients of spiral feeding and vibration 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. According to the CaCO₃ powder classification experimental results, the vibration feeding is conducive to improving classification performances of the pneumatic classifier, especially under the operating condition with high feeding speed, ascompared to the spiral feeding 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 these paration efficiency between coarse particles and fine particles.

Conclusion Compared to the spiral feeding method, the vibration feeding method is conducive to improving the classification performances 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 adversely affects 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.

Keywords: powder; pneumatic classification; feeding methods; fish-hook effect

Get Citation:YU Y, LIU K R, LIU X Y, et al. Influence of feeding methods on classification performance of powder pneumatic classification and cause analyses[J]. China Powder Science and Technology, 2024, 30(2): 36-44.

Received: 2023-10-12,Revised:2023-11-27,Online:2024-01-16。

Funding Project:国家自然科学基金项目,编号:52174234。

First Author:于源(1976—),女,副教授,博士,硕士生导师,研究方向为粉体分离技术及设备研发、智能制造及工业自动化。E-mail: yuyuan@mail.buct.edu.cn。

DOI:10.13732 / j.issn.1008-5548.2024.02.004

CLC No: TQ028; TB4              Type Code:A

Serial No:1008-5548(2024)02-0036-09