浅层喷动床中高密度颗粒流化规律的实验和模拟研究  

Experimental and simulation study on fluidization behavior of high‐density particles in a shallow spouted bed

作　　者：蒋琳 张同旺[2] 刘荣正[1] 邵友林[1] 刘兵[1] 刘马林[1] JIANG Lin;ZHANG Tongwang;LIU Rongzheng;SHAO Youlin;LIU Bing;LIU Malin(Institute of Nuclear and New Energy Technology,Tsinghua University,Beijing 100084,China;Research Institute of Petroleum Processing Co.,Ltd.,SINOPEC,Beijing 100083,China)

机构地区：[1]清华大学核能与新能源技术研究院,北京100084 [2]中国石油化工股份有限公司石油化工科学研究院,北京100083

出　　处：《中国粉体技术》2025年第2期1-14,共14页China Powder Science and Technology

基　　金：国家科技重大专项项目,编号:ZX06901;国家高层次人才特殊支持计划青年拔尖人才项目,编号:20224723061;国家自然科学基金项目,编号:22478220。

摘　　要：【目的】为了获取高温气冷堆(high-temperature gas-cooled reactors,HTGRs)核燃料制备过程中所用的高密度颗粒在浅层喷动流化床内的运动信息,分析颗粒流化状态与工艺参数间的数学关系。【方法】通过流化实验获取高密度颗粒的流化曲线和最小喷动气速的规律;采用磁性颗粒示踪(magnetic particle tracking,MPT)测量方法和计算流体力学-离散单元法(computational fluid dynamics-discrete element method,CFD-DEM),实验获得颗粒在环隙区的局部停留时间,分别探讨局部停留时间随颗粒装载量和入口气速的变化关系,以及与模拟结果的比较。【结果】浅层喷动床中,最小喷动气速与颗粒密度、载荷和气体入口直径等参数有关;磁性颗粒示踪方法可以测量出具有随机性质的局部停留时间;装载量N=2000颗粒系统随着入口气速从45 m/s增大至55 m/s,全部颗粒局部停留时间的平均值从0.032 s缩短至0.028 s,实验和模拟结果保持一致,且流化状态在大装载量和中气速条件下趋于稳定。【结论】磁性颗粒示踪方法不仅可以有效测量浅层喷动床内高密度颗粒的局部停留时间,还可用于快速判断床内流型,有助于指导优化包覆工艺条件和设计放大路线。Objective Tristructural-isotropic(TRISO)nuclear fuel particles serve as the primary barrier to ensure the inherent safety of high-temperature gas-cooled reactors(HTGRs).These particles are coated with four layers using the fluidized bed-chemical vapor deposition(FB-CVD)technique.The fluidizing medium contains high-density uranium dioxide particles,reaching up to 10.8 g/cm3,and the particle motion directly affects the coating quality.Therefore,it is necessary to measure the motion charac-teristics of high-density particles in a shallow spouted bed and analyze the mathematical relationship between fluidization states and operating parameters.Methods Initially,bed pressure drop curves and minimum spouting velocities were obtained for particle systems with different loadings,and the fluidization behavior of high-density particles was explored.Then,magnetic particle tracking(MPT)and computational fluid dynamics-discrete element method(CFD-DEM)were employed.The local residence time of particles in the annular region was measured experimentally under different particle loadings(N=500,1000,2000)and gas inlet velocities,and the results were compared with simulation results.Finally,fast Fourier transform(FFT)analysis was applied to the signal curves of magnetic field strength,enabling rapid determination of particle flow patterns under certain loadings and gas velocities.Results and Discussion The results showed that in high-density particle systems,the bed pressure drop increased continuously with increasing inlet gas velocity,and the flow pattern transitioned from a fixed state to a spouted bed state,without a distinct pressure drop or a plateau phase.The turning point on the fluidization curve,corresponding to the transition in flow pattern,determined the minimum spouting velocity and was influenced by particle density,loading,and gas inlet diameter.MPT mea-surements showed that the local residence time of individual particles in the three-dimensional space tracked by two detectors varied randomly.Increased loading stab

关 键 词：高密度颗粒 喷动床 停留时间 磁性示踪 离散单元法 数值模拟 

分 类 号：TB021.1[一般工业技术] TB4