在线检测中不同形状煤粉颗粒的流动特性  

Flow characteristics of pulverized coal particles with different shapes in online detection

作　　者：姬厚展 高正阳[1] 李永华[1] 宋杨凡 JI Houzhan;GAO Zhengyang;LI Yonghua;SONG Yangfan(Department of Power Engineering,North China Electric Power University,Baoding 071003,China)

机构地区：[1]华北电力大学动力工程系,河北保定071003

出　　处：《中国粉体技术》2023年第1期1-9,共9页China Powder Science and Technology

基　　金：北京市自然科学基金青年项目,编号:3214056。

摘　　要：基于图像识别技术在煤粉二值化图像中进行煤粉颗粒基本特征的提取;建立煤粉颗粒和在线检测装置的三维几何模型;设定气固两相的模拟参数及边界条件后,采用CFD-DEM耦合方法模拟煤粉的气固两相流动,进行气相速度场的分析以及颗粒相的流动分析,研究颗粒的扩散机理,获得颗粒相的速度场和体积分数的分布,归纳出颗粒的流动特性。结果表明:气相在主流通道内流动比较均匀,沿管径增大方向流速逐渐减小;在检测通道内有比较明显的旋涡生成,湍流卷吸效应影响了煤粉颗粒影像的清晰度;形状规则的球形颗粒更易偏离主流流动方向,形成颗粒沉积;形状不规则的颗粒受气力输运作用影响较大,大部分在煤粉气流主流通道内流动;在颗粒受湍流卷吸效应偏离主流流动通道后,粒径较小的颗粒更易运动至检测通道两侧检测元件附近从而影响检测效果。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.

关 键 词：在线检测 煤粉颗粒 流动特性 图像识别 速度场 

分 类 号：TQ536[化学工程—煤化学工程]