Simulation analysis on effects of spargers and baffles in three-phase fluidized bed

doi:10.11949/0438-1157.20250174

Abstract

Abstract:

Three-phase fluidized bed reactor is characterized by a complex, non-uniform, and dynamic structure. To gain a deeper understanding of the influence of internal component design parameters on the performance of three-phase reactors, this study employs the Eulerian-Eulerian multi-fluid model in conjunction with the open-source software OpenFOAM to conduct numerical simulations of internal components within a gas-liquid-solid fluidized bed. The investigation focuses on the effects of three different porosities (0.866, 0.219, 0.072) of spargers and two distinct baffle heights (20 m, 6.8 m) on the flow behavior of particles and gas. The results show that the total bubble volume density of the three types of distributors with three opening ratios is the highest when the opening ratio is 0.219, which is 12.4% and 22.6% higher than that of the total opening ratios of 0.866 and 0.072, respectively. Reducing the baffle height from 20 m to 6.8 m led to an increased bubble count in the upper bed layers, resulting in a 13.4% increase in the total bubble number in the fully developed section.

Key words: three-phase fluidized bed, spargers, baffle, PBM, bubble size

摘要：

三相流化床反应器具有复杂的非均匀动态结构，为了深入理解内构件设计参数对三相反应器性能的影响，基于欧拉-欧拉多流体模型，使用开源软件OpenFOAM对气液固三相流化床内构件进行数值模拟，考察了三种开孔率（0.866、0.219、0.072）的分布器和两种挡板高度（20 m，6.8 m）对颗粒、气体流动的影响。研究结果表明，三种开孔率的分布器在开孔率为0.219时总气泡体积密度最高，相较于0.866和0.072的总开孔率气泡体积密度分别增加了12.4%和22.6%。挡板位置从20 m降低到6.8 m使得更高的床层中有更多的气泡数量，在充分发展段其总气泡数增加了13.4%。研究结果为三相流化床内构件设计提供了依据。

关键词: 三相流化床, 分布器, 挡板, 群平衡, 气泡尺寸

CLC Number:

TQ 021.1

Zicheng ZHU, Yunpeng JIAO, Mengxi LIU, Jianhua CHEN. Simulation analysis on effects of spargers and baffles in three-phase fluidized bed[J]. CIESC Journal, 2025, 76(8): 3873-3884.

朱紫橙, 焦云鹏, 刘梦溪, 陈建华. 三相流化床内分布器与挡板效应的模拟分析[J]. 化工学报, 2025, 76(8): 3873-3884.

Figures/Tables 18

References 44

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Parameter	Value
reactor diameter/m	3.2
reactor straight section height/m	30
superficial gas velocity/(mm/s)	22.588
superficial liquid velocity/(mm/s)	2.768
bubble size/mm	2—10
gas phase density/(kg/m³)	5.57 (15 MPa, 623.15 K)
gas phase viscosity/(Pa·s)	1.48 × 10^-5 (623.15 K)
liquid phase density/(kg/m³)	780 (623.15 K)
liquid phase viscosity/(Pa·s)	0.0187 (15 MPa, 623.15 K)
temperature and outlet pressure conditions	623.15 K/15 MPa
catalyst packing height/m	18
particle density/(kg/m³)	1500
particle shape	spherical
particle size/mm	0.6
particle packing fraction	0.41
time step/s	0.005

Parameter	Value
reactor diameter/m	3.2
reactor straight section height/m	30
superficial gas velocity/(mm/s)	22.588
superficial liquid velocity/(mm/s)	2.768
bubble size/mm	2—10
gas phase density/(kg/m³)	5.57 (15 MPa, 623.15 K)
gas phase viscosity/(Pa·s)	1.48 × 10^-5 (623.15 K)
liquid phase density/(kg/m³)	780 (623.15 K)
liquid phase viscosity/(Pa·s)	0.0187 (15 MPa, 623.15 K)
temperature and outlet pressure conditions	623.15 K/15 MPa
catalyst packing height/m	18
particle density/(kg/m³)	1500
particle shape	spherical
particle size/mm	0.6
particle packing fraction	0.41
time step/s	0.005

Parameter	Value
bed diameter/m	0.254
bed height/m	2.5
superficial gas velocity/(m/s)	0.04
superficial liquid velocity/(m/s)	0.06
air density/(kg/m³)	1.29
liquid phase density/(kg/m³)	1000
solid particle density/(kg/m³)	2500
particle diameter/mm	2.3

Parameter	Value
bed diameter/m	0.254
bed height/m	2.5
superficial gas velocity/(m/s)	0.04
superficial liquid velocity/(m/s)	0.06
air density/(kg/m³)	1.29
liquid phase density/(kg/m³)	1000
solid particle density/(kg/m³)	2500
particle diameter/mm	2.3

Parameter	Value
bed diameter/m	0.15
bed height/m	4.35
superficial gas velocity/(m/s)	0.031
superficial liquid velocity/(m/s)	0.049
air density/(kg/m³)	1.2
liquid phase density/(kg/m³)	997.4
liquid phase viscosity/(Pa·s)	3.322 × 10^-3
solid particle density/(kg/m³)	2460
particle diameter/mm	0.48