Gas-solid fluidized bed has been used in many links of natural uranium conversion process due to its advantages such as high gas-solid contact efficiency and fast interphase mass and heat transfer.However,the current understanding of fluidization reaction performance of high-density particle systems remains insufficient,complicating precise design and control efforts.This work employs the computational particle fluid dynamics(CPFD)method to conduct a comprehensive three-dimensional numerical simulation of an industrial-scale continuous U3O8 reduction fluidized bed system,focusing on the statistical analysis and comparison of key parameters such as macroscopic gas-solid flow,heat transfer,and reaction characteristics across different particle size distributions within the fluidized bed reduction system.The results indicate that under conditions of 80％excess hydrogen,the fluidization state of particles with three different sizes performs poorly,with most particles in a non-fluidized state and low bed expansion ratios observed.Analysis of the product distribution at the gas and solid outlets reveals that smaller particle sizes correspond to higher system temperatures and product conversion rates.However,due to the generally poor fluidization state,even with smaller particle sizes,the overall conversion rate remains low.This result suggests that further optimization of operational conditions and structural configuration of the fluidized bed may be necessary in practice to enhance fluidization effects and reaction conversion rates.Through this study,we aim to offer new perspectives and methodologies for a deeper understanding of the flow and reaction characteristics of high-density particles in fluidized beds,providing robust support for technological advancements in nuclear chemical engineering and related fields.
关键词
气固流化床/氢还原/高密度颗粒/计算颗粒流体力学/数值模拟/天然铀转化/核化工
Key words
gas-solid fluidized bed/hydrogen reduction/high-density particles/CPFD/numerical simulation/natural uranium conversion/nuclear chemical engineering
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