摘要
在密相床层内安装内构件可显著改善工业流化床的流化质量、强化气固传质和提高化学反应效率。由于长时间受气体和颗粒的挤压和冲击,流化床内构件可能会发生变形或断裂。为实现流化床内构件设计的科学性,确保其长周期可靠性,需要明确其受力机理与不同操作条件下受力特性。利用粗粒化CFD-DEM-IBM方法,实现了利用笛卡儿网格模拟流化床中倾斜挡板内构件受力特性的定量模拟,该方法拓展原有挡板应力统计方法,获得了不同倾斜角度对挡板所受应力的定量影响规律。模拟所得挡板受力随时间的演化曲线与实验报道较为一致,在流化床启动阶段会出现较大的峰值,同时成功复现在启动阶段的峰值受力总体与挡板在水平面上的投影面积成正比。模拟结果显示,在启动阶段,挡板受力中颗粒挤压作用力占主导,但在流化阶段,除颗粒作用力达到极大值外的大部分时间中挡板受到的气相压差力要大于颗粒作用力。当挡板倾斜角度较小时,挡板受力较大但抑制床内返混效果较好,因此在工业流化床内构件设计中应兼顾强化传递及长周期可靠性的需求,当挡板倾斜角度较小时应选择强度大的挡板材料。
Installing internal components in the dense-phase bed can significantly improve the fluidization quality of the industrial fluidized bed,enhance gas-solid mass transfer and improve chemical reaction efficiency.Due to the instantaneous impulse and long-term erosion of gases and particles,the internal components may deform or fracture.Therefore,it is necessary to comprehend their mechanical characteristics to optimize the design and implementation of the internal components of the fluidized bed.This article presents coarse-grained CFD-DEMIBM simulation on the forces exerted on an inclined baffle using Cartesian grids.Furthermore,it extends the current stress statistical methodology to analyze the stress on baffles with varying tilt angles.The simulation results are compared to the experimental results,revealing that the simulated force curve of the baffle matches well in both trend and numerical values.Specifically,the particle force dominates the combined force acting on the baffle at the start-up stage,but during the normal fluidization stage,except for the maximum particle force,the gas phase pressure difference acting on the baffle is greater than the particle force for most of the time.As the tilt angle of the baffle decrease,the force acting on the baffle increases and the ability to inhibit the back-mixing enhances,so it is recommended to select a mechanically stronger baffle with the small inclination angle.
作者
赵碧丹
代伊杨
王军武
张永民
ZHAO Bidan;DAI Yiyang;WANG Junwu;ZHANG Yongmin(State Key Laboratory of Multiphase Complex Systems,Institute of Process Engineering,Chinese Academy of Sciences,Beijing 100190,China;School of Chemical Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Heavy Oil Processing,China University of Petroleum,Beijing 102249,China)
出处
《化工学报》
EI
CSCD
北大核心
2024年第1期255-267,共13页
CIESC Journal
基金
中国科学院战略性先导科技专项(XDA29040200)
中国科学技术协会青年人才托举工程项目(2022QNRC001)
国家自然科学基金项目(22378399,21978295)
国家重点研发计划项目(2021YFB1715500)。