Investigating the Effect of Inlet Velocity on Temperature Distribution and Solid Volume Fraction in Fluidized Bed Dryer using CFD

An experimental 2-D fluidized bed was developed to study gas-solid hydrodynamics. The effects of multiple jet systems were examined using Particle Image Velocimetry (PIV) combined with Digital Image Analysis (DIA). Flow regimes were classified through pressure drop spectral analysis. The combination of these non-intrusive techniques allowed for the development of a solid volume fraction correlation. The experimental results show new void fraction regimes of multiple interacting jets. Jet systems combined to promote gas solid mixing and decrease particle dead zones within the bed. It was determined that the validation of multiple jet Discrete Particle Model simulations cannot be exclusively confirmed from single jet studies.

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CFD Simulation of Heat Transfer in Fluidized Bed Reactor

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.493.267 ◽

2014 ◽

Vol 493 ◽

pp. 267-272

Author(s):

I. Nyoman Suprapta Winaya ◽

I. Made Agus Putrawan ◽

I. Nyoman Gede Sujana ◽

Made Sucipta

Keyword(s):

Heat Transfer ◽

Fluidized Bed ◽

Cfd Simulation ◽

Volume Fraction ◽

Solid Volume Fraction ◽

Navier Stokes ◽

Velocity Variation ◽

Navier Stokes Equation ◽

Program Language ◽

The Heat Transfer Coefficient

This study aims to predict heat transfer from a heated bed in a gas fluidized bed using Syamlal-OBrien drag coefficient. Discrete particles model with the Navier-Stokes equation and Eulerian multiphase are used to approach heat transfer simulation. Coefficient of heat transfer which is related to Nusselt Number and volume fraction are calculated using Gunn model which was compiled from C++ program language. The effect of fluidization velocity variation on the heat transfer coefficient comes to the fore, indicating the heat transfer and solid volume fraction at the bed height are very dependent. Contour of solid volume fraction and temperature distribution are also presented.

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Application of Particle Imaging Method for Measurement of Solid Volume Fraction in Carbon Nanotube Particles Fluidized Bed

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i3.33.18530 ◽

2018 ◽

Vol 7 (3.33) ◽

pp. 85 ◽

Cited By ~ 1

Author(s):

Sung Won Kim ◽

. .

Keyword(s):

Carbon Nanotube ◽

Fluidized Bed ◽

Volume Fraction ◽

Particle Density ◽

Solid Volume Fraction ◽

Fixed Bed ◽

Apparent Volume ◽

Previous Method ◽

Imaging Method ◽

Particle Imaging

Solid volume fraction in the carbon nanotube (CNT) fluidized bed reactors is an important parameter which is responsible of fluidization quality and the design of reactor. The solid volume fraction can be obtained from the pressure drop across the bed with the information of gas and particle densities. However, previous method such as the Hg-porosimetry for the measurement of the particle density did not adequately draw the solid volume fraction of the CNT aggregates with entangled nanotubes network. A new method to measure the apparent particle density of the CNT aggregates was proposed to calculate the solid volume fraction in the CNT fluidized bed. The density of the vertically aligned CNT particle was measured based on the apparent volume by shape analysis using two dimensional imaging. The solid fraction based on imaging method showed a significant value of 0.69 for the fixed bed, which describes well the entangled structure of the CNT aggregates. The distribution of solid volume fraction in the CNT fluidized bed with variation of gas velocity was determined based on the imaging method. The method was verified by applying the obtained values to the Richardson-Zaki equation on the bed expansion in the fluidized bed.

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Computational Analysis of the Hydrodynamic Behavior for Different Air Distributor Designs of Fluidized Bed Gasifier

Frontiers in Energy Research ◽

10.3389/fenrg.2021.692066 ◽

2021 ◽

Vol 9 ◽

Author(s):

Naveed Raza ◽

Muhammad Ahsan ◽

Muhammad Taqi Mehran ◽

Salman Raza Naqvi ◽

Iftikhar Ahmad

Keyword(s):

Pressure Drop ◽

Fluidized Bed ◽

Volume Fraction ◽

Solid Volume Fraction ◽

Perforated Plate ◽

Column Height ◽

Thermochemical Conversion ◽

Open Area ◽

Slotted Plate ◽

Distributor Plate

Fluidized bed gasification has proven to be an appropriate technique for converting various biomass feedstocks into helpful energy. Air distributor plate design is one of the critical factors affecting the thermochemical conversion performance of fluidized bed gasifiers. The present study is proposed to investigate the mixing pattern and pressure drop across different configurations of air distributors using a two-fluid model (TFM) of finite volume method-based solver ANSYS FLUENT. The pressure drop across the bed and mixing pattern have been investigated through qualitative and quantitative analysis of CFD results using three diverse distributor plate designs: perforated plate, 90° slotted plate, and 45° swirling slotted plate. The pressure drop by employing the perforated distributor plate reveals the highest pressure drop due to the smallest open area ratio. However, the pressure drop in the case of 90° slotted plate is found to be 7% and 4% lesser than perforated and 45° slotted plate respectively due to a smaller velocity head developed through the wider open area of the straight slotted plates. The distributor design configuration having a 45° slotted plate exhibits considerable pressure drop compared to the 90° slotted plate due to the longer path length of the slot. Numerical pressure drop results across the bed with different types of distributor plates prove reasonable agreement with the experimental results available in the literature. Mixing behavior in perforated distributor plates exhibits lower portion solid volume fraction of around 0.58. However, it falls rapidly as go up the riser (7.7% of column height); 90° slotted plate shows bottom region solid volume fraction of around 0.5. In addition, it exhibits an even broader range of sand volume fraction and column height (13.46% of column height). Finally, the 45° distributor plate reveals the highest range of volume fraction through the riser height (17.3% of column height), indicating the better mixing characteristics of the fluidized zone.

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Three-Dimensional Simulation of Gas-Solid Flow in the Biomass Circulating Fluidized Bed Gasifier’s Riser

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.383-390.6537 ◽

2011 ◽

Vol 383-390 ◽

pp. 6537-6542

Author(s):

Wen Yi Chen ◽

Xin Liu ◽

Xiao Xu Fan ◽

Lei Zhe Chu ◽

Yi Mei Yang ◽

...

Keyword(s):

Pressure Drop ◽

Fluidized Bed ◽

Circulating Fluidized Bed ◽

Volume Fraction ◽

Mutual Influence ◽

Solid Volume Fraction ◽

Three Dimensional ◽

Momentum Exchange ◽

Solid Flow ◽

Radial Profiles

Using the Gidaspow model as the momentum exchange coefficient to take a full-loop simulation of miniature circulating fluidized bed gasifier (CFBG) in the lab, and taking mutual influence of different parts in consideration, it focus on the gas-solid flow structure in the riser in this paper. The heterogeneous behavior in the CFBG riser and the radial profiles of solid volume fraction under different solid inventories in simulation are showed in this paper as a replenishment of certain data which are hard to measure in experiments. The results showed it can’t form an obvious core-annulus flow because of the riser’s high height-diameter ratio and the big refeed line diameter. There are clusters growing and dissipation in a short time. A turning point of pressure drop may be seem as a separation of dense area and dilute area.The three-dimensional (3D) simulation revealed the solid flux and the pressure drop agree with the experimental data.

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Simulation Studies of Gas-Solid in the Riser of a Circulating Fluidized Bed

18th International Conference on Fluidized Bed Combustion ◽

10.1115/fbc2005-78014 ◽

2005 ◽

Cited By ~ 2

Author(s):

Ahmad Hussain ◽

Farid Nasir Ani ◽

Amer Nordin Darus ◽

Azeman Mustafa ◽

Arshad A. Salema

Keyword(s):

Gas Phase ◽

Fluidized Bed ◽

Turbulence Model ◽

Circulating Fluidized Bed ◽

Volume Fraction ◽

Solid Volume Fraction ◽

Design Parameters ◽

Cfd Model ◽

End Effects ◽

Wide Range

A numerical parametric study was performed on the influence of various riser exit geometries on the hydrodynamics of gas-solid two-phase flow in the riser of a Circulating Fluidized Bed (CFB). A Eulerian continuum formulation was applied to both phases. A two fluid framework has been used to simulate fully developed gas-solid flows in vertical riser. A two dimensional Computational Fluid Dynamics (CFD) model of gas-particle flow in the CFB has been investigated using the code FLUENT. The turbulence was modeled by a k-ε turbulence model in the gas phase. The simulations were done using the geometrical configuration of a CFB test rig at the Universiti Teknologi Malaysia (UTM). The CFB riser column has 265 mm (width), 72 mm (depth) and 2.7 m height. The riser is made up of interchangeable Plexiglas columns. The computational model was used to simulate the riser over a wide range of operating and design parameters. In addition, several numerical experiments were carried out to understand the influence of riser end effects, particle size, gas solid velocity and solid volume fraction on the simulated flow characteristics. The CFD model with a k-ε turbulence model for the gas phase and a fixed particle viscosity in the solids phase showed good mixing behaviour. These results were found to be useful in further development of modeling of gas solid flow in the riser.

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