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

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.

Genetic Programming based Drag Model with Improved Prediction Accuracy for Fluidization Systems

2017 ◽  
Vol 15 (2) ◽  
Author(s):  
R. R. Sonolikar ◽  
M. P. Patil ◽  
R. B. Mankar ◽  
S. S. Tambe ◽  
B. D. Kulkarni
Keyword(s):  
Pressure Drop ◽  
Genetic Programming ◽  
Drag Coefficient ◽  
Prediction Accuracy ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Superior Performance ◽  
Momentum Exchange ◽  
Drag Model ◽  
Parameter Ranges

Abstract The drag coefficient plays a vital role in the modeling of gas-solid flows. Its knowledge is essential for understanding the momentum exchange between the gas and solid phases of a fluidization system, and correctly predicting the related hydrodynamics. There exists a number of models for predicting the magnitude of the drag coefficient. However, their major limitation is that they predict widely differing drag coefficient values over same parameter ranges. The parameter ranges over which models possess a good drag prediction accuracy are also not specified explicitly. Accordingly, the present investigation employs Geldart’s group B particles fluidization data from various studies covering wide ranges of Re and εs to propose a new unified drag coefficient model. A novel artificial intelligence based formalism namely genetic programming (GP) has been used to obtain this model. It is developed using the pressure drop approach, and its performance has been assessed rigorously for predicting the bed height, pressure drop, and solid volume fraction at different magnitudes of Reynolds number, by simulating a 3D bubbling fluidized bed. The new drag model has been found to possess better prediction accuracy and applicability over a much wider range of Re and εs than a number of existing models. Owing to the superior performance of the new drag model, it has a potential to gainfully replace the existing drag models in predicting the hydrodynamic behavior of fluidized beds.

Validation and Application of Computational Modeling to Reduce Erosion in a Circulating Fluidized Bed Boiler

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Peter J. Blaser ◽  
Giorgio Corina
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Complex Geometry ◽  
Three Dimensional ◽  
Palm Kernel ◽  
Operational Experience ◽  
Solid Flow ◽  
Internal Surfaces ◽  
And Performance ◽  
Palm Kernel Shells

Abstract The 40 MW Strongoli power plant, located in the Calabria region of Italy, produces power from 100% biomass sources. The combustion of wood biomass, exhausted olive residues and palm kernel shells, occurs in a sand-filled, Circulating Fluidized Bed (CFB) combustor. Operational experience with the unit dates back to 2003. This paper describes the optimization of the boiler in order to minimize erosion on internal surfaces and structures. Detailed three-dimensional, transient, multiphase gas-solid flow fields were computed and are presented. Details of the complex geometry include the combustion chamber, cyclone, cyclone dipleg, seal pot, fluidized bed heat exchanger and cyclone outlet structures including suspension tubes. The gas-solid flow was computed using the commercially-available software package Barracuda, a CFD software based on a unique Eulerian-Lagrangian formulation that was essential to the success of the subject work. Both instantaneous and time-averaged results were obtained. Results were validated against operational erosion experience. The validated model, in turn, was utilized to redesign various components of the boiler, optimizing both erosion characteristics and performance behaviour of the system. The redesigned unit was commissioned in early 2012.

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

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.

Relationship between Solid Flow Rate and Pressure Drop in the Riser of a Pressurized Circulating Fluidized Bed

2016 ◽  
Vol 49 (7) ◽  
pp. 595-601 ◽  
Author(s):  
Muhammad Shahzad Khurram ◽  
Jeong-Hoo Choi ◽  
Yoo Sube Won ◽  
A-Reum Jeong ◽  
Ho-Jung Ryu
Keyword(s):  
Pressure Drop ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Circulating Fluidized Bed ◽  
Solid Flow

Hydrodynamics Simulation of Gas-Solid Flow Field in Conveying Vessel

2011 ◽  
Vol 236-238 ◽  
pp. 1528-1531
Author(s):  
Yue Cui ◽  
Hong Gao ◽  
Jin Sheng Sun ◽  
Xu Chen
Keyword(s):  
Flow Field ◽  
Uniform Distribution ◽  
Volume Fraction ◽  
Dead Zone ◽  
Solid Volume Fraction ◽  
Three Dimensional ◽  
Gas Velocity ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Solid Flow

Flow field of gas and particles in a conveying vessel is investigated by use of a three-dimensional model combined Eulerian approach. Because of the nozzles’ arrangement in this study, the flow patterns of spouts and bubbles can be seen in the gas-solid flow field, which lead to a non-uniform distribution of gas velocity. Solid volume fraction is high near the bottom and low at the top part. The porosity rises with gas speed increasing, as well as time. An improvement is examined to remove the dead zone at the bottom, which results in particles remaining.

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

2005 ◽  
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.

scholarly journals Three-dimensional Numerical Simulation of Dense Gas-Solid Flow in Circulating Fluidized Bed under Rolling Motion of Ship

2010 ◽  
Vol 45 (Special) ◽  
pp. 1004-1011 ◽  
Author(s):  
Hideyuki Oka ◽  
Hiroyuk Murata ◽  
Kazuyoshi Harumi ◽  
Tomokazu Kuwayama ◽  
Kazumasa Tsuboi ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Three Dimensional ◽  
Rolling Motion ◽  
Dense Gas ◽  
Solid Flow
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