JI Houzhan， GAO Zhengyang， LI Yonghua， SONG Yangfan

(Department of Power Engineering， North China Electric Power University， Baoding 071003， China)

Abstract: Based on image recognition technology, the basic characteristics of pulverized coal particles were extracted from binary images. Three-dimensional geometric model of pulverized coal particle and online detection device were established. CFD-DEM coupling method was used to simulate the gas-solid two-phase flow of pulverized coal after setting the simulation parameters and boundary conditions of gas-solid two-phase. Through the analysis of gas velocity field and particle phase flow, the diffusion mechanism of particles were studied. The velocity field and volume fraction distribution of particle phase were obtained and the flow characteristics of particles were summarized. The results show that the gas flow in the mainstream channel is relatively uniform, and the flow velocity gradually decreases along the direction of diameter increase. There is obvious vortex generation in the observation channel, and the turbulent entrainment effect affects the clarity of the pulverized coal particle image. Spherical particles with regular shape are more likely to deviate from the main flow direction, forming unnecessary particle deposition. Irregularly shaped particles are greatly affected by the pneumatic transport, and most of them flow in the main flow channel of the pulverized coal flow. After the particles are deviated from the mainstream flow channel by the turbulent entrainment effect, the smaller particles are more likely to move to the vicinity of the detection elements on both sides of the observation channel so as to affect the detection effect.

Keywords: online detection; pulverized coal particles; flow characteristics; image recognition; velocity field

Received： 2022-06-02，Revised：2022-10-28,Online：2022-11-19 17:49。

Funding Project：北京市自然科学基金青年项目，编号：3214056。

Funding Project：姬厚展(1997—)，男，硕士研究生，研究方向为高效清洁燃烧与环境污染控制。E-mail： jihouzhan@163.com。

First Author：李永华(1968—)，男，教授，硕士生导师，研究方向为锅炉节能与优化。E-mail： liyonghua@126.com。