化工学报 ›› 2022, Vol. 73 ›› Issue (6): 2649-2661.doi: 10.11949/0438-1157.20211701

• 流体力学与传递现象 • 上一篇    下一篇

气固流化床启动阶段挡板内构件受力特性的CFD-DEM模拟

李铁男1,2(),赵碧丹2,3,赵鹏2,3,张永民1(),王军武2,3,4()   

  1. 1.中国石油大学(北京)重质油国家重点实验室,北京 102249
    2.中国科学院过程工程研究所多相复杂系统 国家重点实验室,北京 100190
    3.中国科学院大学化学工程学院,北京 100049
    4.中国科学院绿色过程制造创新研究院,北京 100190
  • 收稿日期:2021-11-29 修回日期:2022-03-11 出版日期:2022-06-05 发布日期:2022-06-30
  • 通讯作者: 张永民,王军武 E-mail:tnli@ipe.ac.cn;zhym@cup.edu.cn;jwwang@ipe.ac.cn
  • 作者简介:李铁男(1996—),男,硕士研究生,tnli@ipe.ac.cn
  • 基金资助:
    国家自然科学基金项目(21978295);中国科学院绿色过程制造创新研究院自主部署项目(IAGM-2019-A13)

CFD-DEM simulation of the force acting on immersed baffles during the start-up stage of a gas-solid fluidized bed

Tienan LI1,2(),Bidan ZHAO2,3,Peng ZHAO2,3,Yongmin ZHANG1(),Junwu WANG2,3,4()   

  1. 1.State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China
    2.State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
    3.School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
    4.Innovation Academy for Green Manufacture, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2021-11-29 Revised:2022-03-11 Published:2022-06-05 Online:2022-06-30
  • Contact: Yongmin ZHANG,Junwu WANG E-mail:tnli@ipe.ac.cn;zhym@cup.edu.cn;jwwang@ipe.ac.cn

摘要:

流化床启动阶段内构件会受到较大的破坏性载荷冲击,为了保障流化床内构件的长周期可靠性,需要掌握这个阶段内构件在流化床内的受力特性。首先提出了一种统计内构件表面受力的方法,将微观颗粒-挡板作用信息转换为宏观挡板受力载荷信息。在此基础上采用CFD-DEM方法,统计分析了流化床启动阶段床层中水平挡板内构件的受力载荷特性。研究结果表明:CFD-DEM方法可半定量复现实验中启动阶段内构件表面受到的动态载荷信号,并复现了表观气速和颗粒粒径对挡板峰值载荷强度的影响规律。本研究证明了内构件表面受力载荷强度统计方法的正确性和CFD-DEM统计分析受力载荷的可行性。

关键词: 内构件, 介尺度结构, 流化床, CFD-DEM方法, 多相流, 数值模拟

Abstract:

In the start-up stage of a fluidized bed, the internal components will be impacted by a large destructive load. In order to ensure the long-term reliability of the internal components of the fluidized bed, it is necessary to master the force characteristics of the internal components in the fluidized bed at this stage. To this end, a method for statistically calculating the stress exerted on the internals from CFD-DEM simulation was proposed, and the simulation results were validated. It was found that the experimentally measured dynamic load impact can be reproduced semi-quantitatively, the effects of superficial gas velocity and particle properties on the load impact can also be predicted. Present study proved not only the correctness of the proposed statistical method, but also the feasibility of extracting the stress exerted on the internals using CFD-DEM method.

Key words: baffle, mesoscale structure, fluidized bed, CFD-DEM method, multiphase flow, numerical simulation

中图分类号: 

  • TQ 021.1

图1

密相床层中挡板表面与颗粒接触示意图(a);等效为“虚拟平面”后颗粒碰撞接触图示(b)"

图2

三维方形冷模流化床实验装置示意图[11]"

图3

模拟采用的流化床几何结构"

表1

挡板床与自由床数值模拟参数"

ParameterValue
bed sizeLx ×Ly ×Lz /mm300×300×2200
baffle sizelx ×ly ×lz /mm60×300×10
particlemean Sauter particle diameter/μm595
density/(kg/m3)2906
voidage at the minimum fluidization condition0.47
minimum fluidization velocity/(m/s)0.33
sphericity0.86
coarse-graining ratio5
coarse-grained particle number3459863
restitution coefficient0.90
friction coefficient0.30
rolling friction coefficient0.01
characteristic velocity/(m/s)0.5
Young’s modulus/Pa1×108
Poisson’s ratio0.3
time step/s1×10-5
gasdensity/(kg/m3)1.2
viscosity/(Pa·s)1.8×10-5
superficial gas velocity/(m/s)0.4, 0.6, 0.9
operating pressure/Pa101325
gas grid size/mm10
time step/s1×10-4

图4

流化床启动阶段内构件所受载荷实验结果与CFD-DEM模拟结果比较"

表2

挡板床数值模拟参数"

ParameterValue
Young’s modulus/Pa1×1085×1081×1092×1093×1095×1091×1010
DEM-time step/s1×10-51×10-51×10-61×10-61×10-61×10-61×10-6
CFD-time step/s1×10-41×10-41×10-51×10-51×10-51×10-51×10-5

图5

不同颗粒杨氏模量下颗粒床层内挡板受到载荷随时间的变化"

图6

不同杨氏模量下颗粒最大重叠量与粒径比值随时间的变化"

图7

不同颗粒碰撞恢复系数(a)、滑动摩擦因数(b)、滚动摩擦因数(c)下颗粒床层内挡板受到载荷随时间的变化"

图8

不同表观气速下颗粒床层内挡板受到载荷随时间的变化"

图9

不同颗粒粒径床层启动阶段挡板受到载荷随时间的变化"

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