密相栓流湿颗粒气力输送数值模拟  

Numerical simulation of pneumatic conveying of wet particles with dense phase plug flow

作　　者：徐止恒 李政权 陈慧敏 张博群 石昊宇 XU Zhiheng;LI Zhengquan;CHEN Huimin;ZHANG Boqun;SHI Haoyu(Jiangxi Provincial Key Laboratory for Simulation and Modelling of Particulate Systems,Jiangxi University of Science&Technology,Ganzhou 341000,China)

机构地区：[1]江西理工大学江西省颗粒系统仿真与模拟重点实验室,江西赣州341000

出　　处：《中国有色冶金》2024年第5期132-140,共9页China Nonferrous Metallurgy

基　　金：国家自然科学基金资助项目(52276154);江西理工大学高层次人才科研启动项目(205200100606)。

摘　　要：鉴于目前对于湿颗粒密相气力输送的研究缺乏成熟的体系与结论,本文探究了湿颗粒密相气力输送的流动机理与流动形态,为气力输送的优化设计提供理论支持。研究采用计算流体力学(computational fluid dynamics,CFD)和离散元法(discrete element method,DEM)双向耦合的数值模拟方法,对水平管道中干湿颗粒料栓的运动形式和颗粒运动轨迹进行了分析,深入研究了颗粒含水率对输送流型、输送效率以及输送压降的影响。结果表明,同等气速下,湿颗粒可以形成段塞流,而干颗粒先是段塞流,随后料栓被气体击穿演变为沙丘流,最后成为管底流;随着气体速度的增大,单位长度的水平管道压降数值呈现先降低后增长的趋势,在质量流率0.5 kg/s、含水率5%的工况下,输送速度为9 m/s时管道压降数值最低,为最佳经济速度值;湿颗粒的压力曲线一直处于波动较大的不稳定状态,当两个监测点位于段塞外部时,轴向压差几乎为零,而当两个监测点位于段塞内部时,轴向压差可以达到-600 Pa。通过对湿颗粒输送时的压降变化进行分析和监测,可及时发现设备故障的迹象,预警可能的问题并采取预防措施,避免设备损坏和生产中断。Given the current lack of a mature system and conclusions regarding the pneumatic conveying of wet granular materials in dense phase,this paper explores the flow mechanisms and flow patterns of wet granular dense phase pneumatic conveying,providing theoretical support for the optimization design of pneumatic conveying systems.The study employs a bidirectional coupling numerical simulation method using computational fluid dynamics(CFD)and discrete element method(DEM)to analyze the motion forms of dry and wet granular plugs in horizontal pipelines and the trajectories of particle movement.It further investigates the impact of moisture content on the conveying flow pattern,conveying efficiency,and pressure drop during conveying.The results indicate that under the same gas velocity,wet particles can form plug flow,while dry particles initially exhibit plug flow,which then evolves into dune flow as the plug is penetrated by the gas,ultimately becoming bottom flow.As the gas velocity increases,the pressure drop per unit length of the horizontal pipeline shows a trend of first decreasing and then increasing.Under the condition of mass flow rate of 0.5 kg/s and water content of 5%,the pipeline pressure drop is the lowest when the conveying speed is 9 m/s,which is the best economic speed value.The pressure curve of wet particles remains in a highly fluctuating unstable state;when two monitoring points are located outside the plug,the axial pressure difference is nearly zero,while when the monitoring points are inside the plug,the axial pressure difference can reach-600 Pa.By analyzing and monitoring the pressure drop changes during the conveying of wet particles,signs of equipment failure can be detected in a timely manner,allowing for early warnings of potential issues and the implementation of preventive measures to avoid equipment damage and production interruptions.

关 键 词：物料输送 密相气力输送 流体力学 离散元法 湿颗粒 段塞流 颗粒含水率 

分 类 号：TF801[冶金工程—有色金属冶金]