于 源^a, 刘克润^a, 刘晓勇^a, 刘家祥^b, 焦志伟^a, 付俊杰^a

(北京化工大学 a. 机电工程学院, b. 材料电化学过程与技术北京市重点实验室, 北京 100029)

引用格式:

于源, 刘克润, 刘晓勇, 等. 喂料方式对气力分级性能的影响及成因分析[J]. 中国粉体技术, 2024, 30(2): 36-44.

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.

收稿日期: 2023-10-12,修回日期:2023-11-27,上线日期:2024-01-16。

基金项目:国家自然科学基金项目,编号:52174234。

第一作者简介: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。

摘要: 【目的】为了提高粉体气力分级设备的分级性能,研究螺旋喂料和振动喂料 2 种不同喂料方式对气力分级性能的影响。 【方法】采用高速摄像机对不同喂料方式下粉体下落运动(喂料)进行图像采集,运用图像处理技术对采集到的图像进行处理,通过图像观察法和引入喂料时连续时刻粉体面积分布变异系数分析喂料方式对粉体分散性的影响;通过碳酸钙粉体分级实验方法探讨喂料方式对分级性能的影响。 【结果】相较于螺旋喂料,振动喂料有利于粉体解团,提升粉体喂料时的均匀性和分散性;相较于螺旋喂料方式,振动喂料有助于提升气力分级机的分级性能,尤其在较高的喂料速度下,分级性能提升效果显著,喂料速度为 18 kg / h 时,分级精度提升 185%,旁路值减小 75%,“鱼钩效应”峰值点高度降低 29%;粒径小于 10 μm 的超细颗粒在粗粉中占比从螺旋喂料时的 11. 4%减小到振动喂料时的 4. 4%,粗粉中细粉占比大幅减小,粗细颗粒分离效果得到改善。 【结论】螺旋喂料不适合输运黏性较强、 流动性较差的粉体,如碳酸钙;振动喂料可改善粉体材料的喂料均匀性和分散程度,有利于提高气力分级机分级性能。

关键词: 粉体; 气力分级; 喂料方式; 鱼钩效应

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

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