三相流化床内分布器与挡板效应的模拟分析

doi:10.11949/0438-1157.20250174

摘要/Abstract

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

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

中图分类号:

TQ 021.1

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.

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.

图/表 18

表1 模拟参数、操作条件及物性参数

Table 1 Simulation parameters， operating conditions and physical property parameters

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

表2 气液固三相流动模拟边界条件

Table 2 Boundary conditions for the simulation of gas-liquid-solid three-phase flow

G&L: interstitialInletVelocity

S: fixedValue

zeroGradient

walls

fixedFluxPressure

G&L: noSlip

S: JohnsonJacksonParticleSlip

zeroGradient

outlet

prghPressure

pressureInletOutletVelocity

inletOutlet

图1 不同网格数在20 m挡板处的气速

Fig.1 Gas velocity at 20 m baffle with different mesh numbers

表3 三相流化床实验参数

Table 3 Experimental parameters of three-phase fluidized bed

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

图2 本文模型计算结果与文献实验结果[32]气含率对比

Fig.2 Comparison of the simulated gas holdup in this work and the experimental results in Ref.[32]

表4 三相流化床实验参数

Table 4 Experimental parameters of three-phase fluidized bed

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

图3 本文模型计算结果与文献[33]中局部固含率实验结果对比

Fig.3 Comparison of the local solid volume fraction between the simulation in this work and the experimental results in Ref.[33]

图4 反应器网格及分布器设置

Fig.4 Grid and sparger settings of the reactor

图5 不同分布器下各区域的气泡数密度

Fig.5 Bubble number density in each region for different spargers

图6 不同分布器下各区域的气泡体积密度

Fig.6 Bubble volume density in each region for different spargers

图7 固含率与相对固含率的轴向分布

Fig.7 Axial distribution of solid volume fraction and relative solid volume fraction

图8 Sparger 1（开孔率0.866）气含率随时间变化

Fig.8 Variation of gas holdup over time in Sparger 1 (porosity 0.866) case

图9 不同分布器下气含率对比

Fig.9 Comparison of gas holdup for different spargers

图10 反应器网格及挡板位置设置

Fig.10 Grid and baffle position setting of the reactor

图11 挡板位置对涡的影响

Fig.11 Effect of baffle position on vortex

表5 不同挡板位置对整体与局部三相含率的影响

Table 5 The effect of different baffle positions on the global and local three-phase volume fraction

Item	Volume fraction
	20 m baffle		6.8 m baffle
	Global	Local	Global	Local
gas phase	0.055	0.055	0.054	0.059
liquid phase	0.700	0.699	0.724	0.697
solid phase	0.244	0.245	0.222	0.243

图12 不同挡板高度下各区域的气泡数密度

Fig.12 Bubble number density in each region at different baffle heights

图13 颗粒轴向速度（VZ ）的径向分布

Fig.13 Radial distribution of particle axial velocity (VZ )

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