蒋 琳¹ ， 张同旺² ， 刘荣正¹ ， 邵友林¹ ， 刘兵¹ ， 刘马林¹

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

引用格式：

蒋琳， 张同旺， 刘荣正， 等. 浅层喷动床中高密度颗粒流化规律的实验和模拟研究［J］. 中国粉体技术， 2025， 31（2）：

1-14.

JIANG Lin， ZHANG Tongwang， LIU Rongzheng， et al. Experimental and simulation study on fluidization behavior of high-den⁃

sity particles in a shallow spouted bed［J］. China Powder Science and Technology， 2025， 31（2）： 1−14.

DOI：10.13732/j.issn.1008-5548.2025.02.001

收稿日期： 2024-09-14， 修回日期： 2024-10-28， 上线日期： 2024-12-31。

基金项目： 国家科技重大专项项目， 编号： ZX06901； 国家万人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。

第一作者简介： 蒋琳（1998—），女，博士生，研究方向为多相流 CFD-DEM 模拟、 流态化行为测量。E-mail：jiang-l20@mails. tsinghua.

edu. cn。

通信作者简介： 刘马林（1983—），男，副教授，博士，博士生导师，研究方向为核燃料制备。E-mail：liumalin@tsinghua. edu. cn。

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流化规律，如流化曲线和最小喷动气速。同时，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T L 。装载量N=2 000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T L 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。

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

Abstract

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/cm 3 ， and the par-ticle motion directly affects the coating quality. Therefore， it is necessary to measure the motion characteristics of high-density par-ticles 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 expe-rimentally under different particle loadings （N=500， 1 000， 2 000） and gas inlet velocities，and the results were compared with simu-lation 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 measurements showed that the   local residence time of individual particles in the three-dimensional space tracked by two detectors varied randomly. Increased loading stabilized fluidization and facilitated particle circulation in a "spouting-fountain-annular region" pattern. Simulation results showed  that at a particle loading of 2 000 （N=2 000）， as the inlet gas velocity increased from 45 m/s to 55 m/s， the local residence time （T L ） fluctuated randomly within a certain value range， with the average time decreasing from 0. 032 s to 0. 028 s. The experimental results were highly consistent with the simulation results. FFT analysis of detector-1's signal curves showed a dominant frequency and   regular spouting pattern at a moderate gas velocity （e. g. U g =55. 26 m/s）.

Conclusion　The distinctive fluidization characteristics for high-density particles， including bed pressure drop behavior and minimum  spouting gas velocity， are revealed. A novel method for tracking the motion of individual particles in three-dimensional space is estab-lished. The MPT method can effectively measure the T L  of high-density particles in a shallow spouted bed under different operating con-ditions and quickly identify flow patterns and fluidization states. The method can support the process optimization and scale-up design  for coating applications.

Keywords： high-density particles； spouted bed； residence time； magnetic tracking； discrete element method； numerical simulation

参考文献（References）

［1］刘荣正， 刘马林， 邵友林， 等. 流化床-化学气相沉积技术的应用及研究进展［J］. 化工进展， 2016， 35（5）： 1263-1272.

LIU R Z，LIU M L，SHAO Y L，et al.Application and research progress of fluidized bed-chemical vapor deposition technology［J］.Chemical  Industryand Engineering Progress，2016，35（5）：1263-1272.

［2］JIANG L，QIU M F，LIU R Z，et al.CFD-DEM simulation of high density particles fluidization behaviors in 3D conical spouted beds[J］. Particuology，2024，88：266-281.

［3］YUE Y H，WANG S，BAHL P，et al.Experimental investigation of spout incoherence in a spouted bed［J］.Chemical Engi-

neering Journal，2021，418：129320.

［4］DE BRITO R C，TELLABIDE M ESTIATI I，et al.Estimation of the minimum spouting velocity based on pressure fluctuation analysis［J］. Journal of the Taiwan Institute of Chemical Engineers，2020，113：56-65.

［5］LUSTRIK M，DREU R,PERPAR M.Influence of perforated draft tube air intake on a pellet coating process[J］.Powder Technology，2018，  330：114-124.

［6］BACCHUWAR S，VIDYAPATI V，QUAN K M，et al.Quantitative bin flow analysis of particle discharge using X-ray radiography［J］.Powder Technology，2019，344：693-705.

［7］MEHDIZAD M，FULLARD L，GALVOSAS P，et al.Quantitative measurements of flow dynamics in 3D hoppers using MRI［J］.Powder Technology， 2021，392：69-80.

［8］RICHTER M C，MAINZA A N，GOVENDER I，et al. Features of near gravitational material tracers in a dense medium cyclone from PEPT［J］.Powder Technology，2023，415：118095.

［9］BUIST K A，JAYAPRAKASH P，KUIPERS J A M，et al.Magnetic particle tracking for nonspherical particles in a cylindrical fluidized bed［J］.AICHE Journal，2017，63（12）：5335-5342.

［10］MEMA I，BUIST K A，KUIPERS J A M，et al.Fluidization of spherical versus elongated particles： experimental investigation using    magnetic particle tracking［J］.AICHE Journal，2020，66（4）：e16895.

［11］HALOW J，HOLSOPPLE K，CRAWSHAW B，et al.Observed mixing behavior of single particles in a bubbling fluidized bed of higher-density particles［J］.Industrial & Engineering Chemistry Research，2012，51（44）：14566-14576.

［12］MOLINER C，MARCHELLI F，SPANACHI N，et al.CFD simulation of a spouted bed：comparison between the discrete element method （DEM）  and the two fluid model （TFM）［J］.Chemical Engineering Journal，2019，377：120466.

［13］ESGANDARI B，RAUCHENZAUNER S，GONIVA C，et al.A comprehensive comparison of two-fluid model，discrete element method and experiments for the simulation of single- and multiple-spout fluidized beds［J］.Chemical Engineering Science，2023，267：118357.

［14］CHEN Y F，ZHONG H B，TANG R Y，et al.CFD Simulation of wet spouted fluidized bed using two-fluid model with variable restitution   coefficient and diameter ［J］.Theoretical Foundations of Chemical Engineering，2023，57（3）：380-390.

［15］YUE Y H，SHEN Y S.CFD-DEM study of spout incoherence phenomena in a conical spouted bed［J］.Powder Technology，2022，406：117529.

［16］蒋琳，张同旺，刘荣正，等. 高密度颗粒流化行为测量的磁性颗粒示踪方法研究［J/OL］.化工学报.（2024-08-22）［2024-10-10］. http：//link. cnki. net/urlid/11. 1946. TQ. 20240822. 1256. 006.

JIANG L，ZHANG T W，LIU R Z，et al. Research on magnetic particle tracing method for measuring fluidization behavior of high-density     particles［J/OL］. CIESC Journal.（2024-08-22）［2024-10-10］. http：// link. cnki. net/urlid/11. 1946. TQ.20240822. 1256. 006.

［17］GOLSHAN S，SOTUDEH-GHAREBAGH R，ZARGHAMI R，et al. Review and implementation of CFD-DEM applied to chemical process systems ［J］. Chemical Engineering Science， 2020， 221：115646.

［18］QIU M F，CHEN Z，JIANG L，et al.Numerical simulation of uranium tetrafluoride fluorination in a multistage spouted bed using the improved CFD−DEM chemical reaction model ［J］. Particuology， 2023， 75： 119-136.

［19］QIU M F，JIANG L，LIU R Z，et al.CFD−DEM simulation of fluorination reaction in fluidized beds with local grid and time refinement method［J］. Particuology， 2024， 84： 145-157.

［20］YURATA T，PIUMSOMBOON P，CHALERMSINSUWAN B.Effect of contact force modeling parameters on the system hydrodynamics of spouted bed  using CFD−DEM simulation and 2 k factorial experimental design［J］. Chemical Engineering Research & Design， 2020， 153： 401-418.

［21］MARCHELLI F，HOU Q F，BOSIO B，et al.Comparison of different drag models in CFD−DEM simulations of spouted beds［J］.Powder Tech- nology， 2020，360： 1253-1270.

［22］OLAZAR M，SAN JOSÉ M J，AGUAYO A T，et al.Stable operation conditions for gas solid contact regimes in conical spouted beds ［J］. Industrial & Engineering Chemistry Research， 1992， 31（7）： 1784-1792.

［23］ROJAS I D L.Preliminary results for the investigation of hydrodynamic scaling relationships in shallow spouted beds［J］.Separation Science and Technology， 2010， 45（12/13）： 1928-1934.

［24］ZHONG W Q，LIU X J，GRACE J R，et al.Prediction of minimum spouting velocity of spouted bed by CFD−DEM：scale-up［J］. Canadian   Journal of Chemical Engineering， 2013， 91（11）： 1809-1814.

［25］PIETSCH S，SCHOENHERR M，JAEGER F K，et al.Measurement of residence time distributions in a continuously operated spouted bed［J］. Chemical Engineering & Technology， 2020， 43（5）： 804-812.

［26］LIU M L，WEN Y Y，LIU R Z，et al.Investigation of fluidization behavior of high density particle in spouted bed using CFD−DEM     coupling method［J］.Powder Technology，2015，280：72-82.

［27］YANG J S，BREAULT R W，ROWAN S L.Experimental investigation of fountain height in a shallow rectangular spouted bed using digital  image analysis［J］.Chemical Engineering Journal，2020，380：122467.