基于CPFD方法的U_(3)O_(8)氢还原流化床反应器数值模拟  

Numerical simulation of hydrogen reduction of U_(3)O_(8) in fluidized bed reactors using CPFD method

作　　者：李舒月 王欢[1,2] 周少强 毛志宏 张永民 王军武[1] 吴秀花 LI Shuyue;WANG Huan;ZHOU Shaoqiang;MAO Zhihong;ZHANG Yongmin;WANG Junwu;WU Xiuhua(State Key Laboratory of Heavy Oil Processing,China University of Petroleum,Beijing 102249,China;CNNC No.7 Research and Design Institute Co.,Ltd.,Taiyuan 030012,Shanxi,China)

机构地区：[1]中国石油大学(北京)重质油全国重点实验室,北京102249 [2]中核第七研究设计院有限公司,山西太原030012

出　　处：《化工学报》2024年第9期3133-3151,F0004,共20页CIESC Journal

基　　金：国家自然科学基金项目(22308377);中国石油大学(北京)拔尖人才启动基金项目(2462023BJRC004);中核集团青年英才项目(KY202212)。

摘　　要：气固流化床因具有气固接触效率高、相间传质传热快等优点已用于天然铀转化工艺的多个环节,但目前对这类高密度颗粒系统的流化反应性能认识不足,难以对其精确设计和操控。采用计算颗粒流体力学(computational particle fluid dynamics,CPFD)方法对工业尺度连续U_(3)O_(8)还原流化床进行全三维数值模拟,对不同颗粒粒径分布的流化床还原系统中宏观气固流动、传热、反应特性等重要参数进行统计分析。结果显示,在氢气过量80%的条件下,3种不同粒径的颗粒在流化床中的流化状态均表现不佳,大部分区域颗粒处于非流化状态,床层膨胀率低。分析出口处产物分布发现,颗粒粒径越小产物的转化率越高,然而由于流化状态普遍较差,即便是在粒径较小的条件下转化率的总体水平仍然偏低。以上结果表明,在实际操作中可能需要进一步优化流化床的操作条件和结构形式,以提高流化效果和反应转化率。本研究期望能够为高密度颗粒在流化床中的流动与反应特性的深入认识提供新的视角和方法,为核化工及相关领域的技术进步提供有力支持。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 U_(3)O_(8) 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 

分 类 号：TQ051.3[化学工程] TQ016