Numerical Analysis on the Dynamic Behaviour of Fluidized Bed Reactor

2015 ◽  
Vol 813-814 ◽  
pp. 718-722
Author(s):  
P.M. Suhaile ◽  
S. Rupesh ◽  
C. Muraleedharan ◽  
P. Arun
Keyword(s):  
Fluid Dynamics ◽  
Fluidized Bed ◽  
Volume Fraction ◽  
Solid Phase ◽  
Fluid Model ◽  
Turbulence Models ◽  
Fluidized Bed Reactor ◽  
Two Fluid Model ◽  
Bed Expansion ◽  
Phase Transport

A gas-solid multiphase flow is simulated using CFD to investigate the fluid dynamics of a fluidized bed reactor. The simulation is based on Euler-Euler two fluid model where Kinetic Theory of Granular Flow is used for predicting the solid phase transport properties. The simulation procedure is validated by reproducing and comparing hydrodynamic parameters with those available in the literature. The effect of different turbulence models on bed fluid dynamics is analyzed and k-ε RNG per-phase model is found to have better prediction accuracy compared to other models. The minimum fluidization velocity, granular temperature, bed expansion, particle velocity and volume fraction are determined by the model.

The effect of ring baffles on the hydrodynamics of a gas—solid bubbling fluidized bed using computational fluid dynamics

2009 ◽  
Vol 223 (10) ◽  
pp. 2281-2289 ◽  
Author(s):  
S H Hosseini ◽  
R Rahimi ◽  
M Zivdar ◽  
A Samimi
Keyword(s):  
Fluidized Bed ◽  
Volume Fraction ◽  
Fluid Model ◽  
Expansion Ratio ◽  
Bubbling Fluidized Bed ◽  
Gas Volume Fraction ◽  
Two Fluid Model ◽  
Particle Velocities ◽  
Bed Expansion ◽  
Gas Volume

An Eulerian—Eulerian two-fluid model (TFM) integrating the kinetic theory for emulsion phase was used to simulate gas—solid fluidized beds. Validation of the model was investigated based on hydrodynamic parameters such as bed expansion ratio, H/ H0, gas volume fraction profile, bubble behaviour, and motion of the particles. A good agreement was found between numerical results and experimental values. The model was used to study a bubbling fluidized bed (BFB) including the ring baffles. Predicted results show that the ring baffles have an important role in the flow pattern of the bed. Baffles increase the bed expansion height and particle velocities at axial locations on the top of the highest baffle as well as uniform distribution of gas volume fraction between the baffles area. In spite of increasing the dead zones in the bed, ring baffles cause the improvement of mixing and heat transfer in the bed. The present study provides a useful basis for further works on the effect of baffles in BFBs.

scholarly journals CFD investigation of slugging behavior in a gas-solids fluidized bed

2017 ◽  
Vol 23 (4) ◽  
pp. 529-536 ◽  
Author(s):  
Yanjun Guan ◽  
Xiuying Yao ◽  
Guiying Wu ◽  
Kai Zhang
Keyword(s):  
Fluidized Bed ◽  
Volume Fraction ◽  
Fluid Model ◽  
Predictive Ability ◽  
Momentum Equation ◽  
Expansion Ratio ◽  
Viscous Force ◽  
Spectrum Density ◽  
Two Fluid Model ◽  
Bed Expansion

The hydrodynamics of a slugging fluidized bed is investigated numerically by using a two-fluid model suggested by Brandani and Zhang [22]. Numerical simulations are carried out in the platform of a commercial software package, CFX 4.4, by adding user-defined subroutines. The bed expansion ratio, the pressure drop fluctuation and its power spectrum density at the equipment scale and the solids volume fraction distributions at the grid scale are predicted to explore the slugging fluidization characteristics for Geldart group D particles. By comparing with the experimental data in the literature, the numerical model is found to have better predictive ability when the viscous force term is considered in the gas phase momentum equation.

Simulation Study of Gas-Solid Macro-Mixing Characterization in Small Fixed-Fluidized Bed Reactor

2011 ◽  
Vol 236-238 ◽  
pp. 1537-1545
Author(s):  
Wen Jing Liu ◽  
Hui Zhao ◽  
Chao He Yang ◽  
Hong Hong Shan
Keyword(s):  
Fluidized Bed ◽  
Raw Materials ◽  
Fluid Model ◽  
Structural Parameters ◽  
Flow Behavior ◽  
Fluidized Bed Reactor ◽  
Operating Conditions ◽  
Laboratory Evaluation ◽  
Two Fluid Model ◽  
Two Fluid

In fixed-fluidized bed reactor, laboratory evaluation of different catalyst, raw materials and process parameters can be implemented, so it has wide applications in the refining process. In this study, we focused on small fixed-fluidized bed reactor, using Eulerian-Eulerian two-fluid model, simulated the gas-solid flow behavior in it. Gas residence time distribution was measured in order to characterize macro-mixing. At the same time, by changing the reactor structure and operating conditions, we studied their effects on gas-solid macro-mixing characterization. The results show that the effects of structural parameters are larger than operating conditions, and different parameters have different effects. Different parameters can be adjusted to change the gas-solid macro-mixing characterization in small fixed-fluidized bed reactor. Therefore, the small fixed-fluidized bed reactor can provide better results in more application areas.

Hydrodynamics of Multiple Size Particles in a Liquid Fluidized Bed Classifier

2003 ◽  
Author(s):  
Dinesh Gera ◽  
Madhava Syamlal ◽  
Thomas J. O’Brien
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fluidized Bed ◽  
Volume Fraction ◽  
Fluid Model ◽  
Operating Conditions ◽  
Particle Sizes ◽  
Two Fluid Model ◽  
Predicted Values

A two fluid model is extended to an N-phase, multi-fluid model, in which each particulate phase represents a collection of particles with identical diameter and density. The current N-phase model is applied to a fluidized bed classifier with six different particle sizes to investigate the effects of different operating conditions—fluidizing liquid flow rate, feed voidage, and particle size distribution in the feed stream—on the particle size distribution inside the classifier and the discharge streams. The predicted volume fraction of different particle sizes is compared with the experimental data reported by Chen et al. (2002) for two columns, 191 mm and 292 mm in diameter, each having different geometries and containing glass beads of different sizes fluidized with water. A fairly good agreement is observed between the measured and predicted values for mono- and poly-dispersed systems.

Numerical Simulation of Fluid Dynamics in a Two-Dimension Gas-Solid Bubbling Fluidized Bed

2010 ◽  
Vol 42 ◽  
pp. 466-470
Author(s):  
Tao Zeng ◽  
Xiang Zhang ◽  
Hai Bo Lin ◽  
Min Zhou ◽  
Kai Cheng
Keyword(s):  
Numerical Simulation ◽  
Fluidized Bed ◽  
Solid Phase ◽  
Fluid Model ◽  
Simulation Method ◽  
Wall Region ◽  
Flow Characterization ◽  
Bubbling Fluidized Bed ◽  
Two Fluid Model

The process of bubbles from formation to eruption was simulated by using the two-fluid model combined with the particle kinetic theory to investigate the flow characterization of gas-solid in a bubbling fluidized bed. The velocity distributions of solid-phase in different axial height were also studied. The results show that the numerical simulation method can success simulates the flow characterization of gas-solid bubbling fluidized bed. The flow characterization in bubbling fluidized bed is circulating flow structure, while the central region is upward flow and the wall region is downward flow. The simulation results agree with the experiment results.

Three-dimensional computational fluid dynamics investigation of hydrodynamics behaviour of gas–solid flow in fluidized bed of Geldart D particles

2021 ◽  
pp. 095440892098769
Author(s):  
Fazia Aiche ◽  
Salah Belaadi ◽  
Adel Lalaoua ◽  
Abdallah Sofiane Berrouk ◽  
Abdelwahid Azzi
Keyword(s):  
Fluidized Bed ◽  
Gas Flow ◽  
Turbulence Modeling ◽  
Volume Fraction ◽  
Solid Phase ◽  
Fluid Model ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Industrial Processes ◽  
Cyclic Process

Fluidized beds are widely used in many industrial processes as they ensure the desirable high-intensity heat and mass transfers between gas and particles and offer the possibility to perform operations in a continuous mode and powders recycling. Some of these industrial processes use Geldart D type of powders and operate in the slugging mode. This paper presents a 3 D numerical model of gas-solid flows in a fluidized bed based on the Two-Fluid Model (TFM). Turbulence modeling (k- ε) was used to predict flow behavior in fluidized bed of Geldart D particles. The solid phase consists of Geldart D powders and the gas flow is in a slug regime. The numerical results are validated against the experimental work of Azzi et al. Model predictions on flow patterns, bed expansion, volume fraction time series and pressure drop fluctuations are presented and discussed in details in order to demonstrate the cyclic process of slug formation (onset, growth, rising and bursting of slugs) and its effects on the overall performance of beds fluidizing Geldart D type of powders.

Sign in / Sign up

Export Citation Format

Share Document