CFD Simulation of Fluid Dynamics in a Gas-Solid Jetting Fluidized Bed

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Qicheng Wang ◽  
Kai Zhang ◽  
Guogang Sun ◽  
Stefano Brandani ◽  
Jinsen Gao ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Fluidized Beds ◽  
Cfd Simulation ◽  
Fluid Model ◽  
Outer Region ◽  
Solid Material ◽  
Fundamental Parameters ◽  
Bed Height ◽  
Two Fluid Model ◽  
Solid Movement

A thorough understanding of fundamental parameters, such as transient and time-averaged gas and solid velocities, is helpful for designing and manipulating the gas-solid jetting fluidized beds. In this study, a new two-fluid model developed in our group is used to investigate numerically the gas and solid velocities in the gas-solid jetting fluidized beds by adding the user-defined Fortran subroutines in the platform of CFX 4.4, a commercial CFD software package. Simulation is carried out in a two-dimensional fluidized bed 2.0 m high and 0.3 m wide equipped with a nozzle in the centre at the inlet. Resin, belonging to Geldart B Group, is selected as the solid material. The numerical results show that the solid movement is predominantly upward in the center of the bed, whilst it is primarily downward in the outer region of the bed. Particles exchange between these two regions across their neighboring boundary. Gas interchange between the jet and the emulsion phase becomes obvious with the jet evolution. The time-averaged distributions of gas and solid velocities in the bed are greatly influenced by jet gas velocity, and the effect of the static bed height can be ignored. These numerical computations provide helpful information for designing and scaling up the jetting fluidized bed.

CFD Simulation Research on Flow Characteristics of Fluidized Beds

2014 ◽  
Vol 881-883 ◽  
pp. 1809-1813
Author(s):  
Li Ning Han ◽  
Lu Min Wang
Keyword(s):  
Particle Size ◽  
Pressure Drop ◽  
Fluidized Bed ◽  
Fluidized Beds ◽  
Particle Distribution ◽  
Cfd Simulation ◽  
Fluid Model ◽  
Flow Characteristics ◽  
Fluidization Velocity ◽  
Motion Characteristics

The Euler-Euler two-fluid model incorporating the kinetic theory of granular flow was applied to simulate the gas-solid flow in fluidized beds. The pressure drop, particle distribution and motion characteristics were studied in this paper. In order to investigate the effect of structure of the fluidized bed on flow characteristics, fluidized beds with different diameters and structures were applied. User defined functions (UDF) were applied to study the flow characteristics when the particle size and mass changed over time. The results showed that with the increase of particle size, higher minimum fluidization velocity was required, but lower pressure drop was obtained. For a certain fluidizing medium, the bed critical fluidization velocity depended only on the size and nature of the particles. The structure of a fluidized bed had an influence on the particle distribution and motion characteristics.

Bubbling Flow in a Multi-Jet Fluidized Bed

2020 ◽  
Author(s):  
Liwu Wang ◽  
Sijun Zhang
Keyword(s):  
Fluidized Bed ◽  
Fluidized Beds ◽  
Fluid Model ◽  
Bubble Formation ◽  
Model Parameters ◽  
Phase Flow ◽  
Two Phase ◽  
Single Jet ◽  
Two Fluid Model ◽  
Two Fluid

Abstract This work concerns with numerical simulation of dense gas-particle two-phase flow in a fluidized bed in the framework of two-fluid model, where attention is given to the bubble formation in a single-jet and multi-jet fluidized beds. The kinetic theory is implemented in the model to avoid empirically determined model parameters. The validity of the approach is confirmed through the comparison between the computed results and the measurements in the literature. The results show that increasing the number of jets results in different behavior in bubble formation and the flow pattern in a multi-jet bed is much more complex than that in a single-jet bed.

scholarly journals Study on Fluidization Characteristics of Magnetically Fluidized Beds for Microfine Particles

Minerals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 61
Author(s):  
Yakun Tian ◽  
Shulei Song ◽  
Xuan Xu ◽  
Xinyu Wei ◽  
Shanwen Yan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Fluidized Bed ◽  
Magnetic Field Strength ◽  
Fluidized Beds ◽  
Expansion Rate ◽  
Gas Velocity ◽  
Bed Height ◽  
Bed Expansion ◽  
The Magnetic Field

The bed pressure drop, minimum fluidized gas velocity, bed density, and bed expansion rate are important parameters characterizing the fluidization characteristics of gas-solid fluidized beds. By analyzing these parameters, the advantages and disadvantages of the fluidization state can be known. In this study, experiments were conducted to study the fluidization characteristics of a gas-solid magnetically fluidized bed for microfine particles by changing the magnetic field strength, magnetic field addition sequence, and static bed height. The experimental results show that when the magnetic field strength increased from 0 KA/m to 5 KA/m, the minimum fluidized gas velocity of particles increased from 4.42 cm/s to 10.32 cm/s, while the bed pressure drop first increased and then decreased. When the magnetic field strength is less than 3.4 KA/m, the microfine particles in the bed are mainly acted on by the airflow; while when the magnetic field strength is greater than 3.4 KA/m, the microfine particles are mainly dominated by the magnetic field. The magnetic field addition sequence affects the fluidization quality of microfine particles. The fluidized bed with ‘adding magnetic field first’ shows a more stable fluidization state than ‘adding magnetic field later’. Increasing of the static bed height reduces the bed expansion rate. The bed expansion rate is up to 112.5% at a static bed height of h0 = 40 mm and H = 5 KA/m. This will broaden the range of density regulation of a single magnetic particle and lay the advantage of gas-solid magnetically fluidized bed for microfine particles in the field of separation of fine coal.

Simulations of vertical jet penetration using a filtered two-fluid model in a gas–solid fluidized bed

Particuology ◽  
2017 ◽  
Vol 31 ◽  
pp. 95-104 ◽  
Author(s):  
Shuyan Wang ◽  
Baoli Shao ◽  
Xiangyu Li ◽  
Jian Zhao ◽  
Lili Liu ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Fluid Model ◽  
Jet Penetration ◽  
Two Fluid Model ◽  
Two Fluid ◽  
Vertical Jet

A two-fluid model for avalanche and debris flows

2005 ◽  
Vol 363 (1832) ◽  
pp. 1573-1601 ◽  
Author(s):  
E. Bruce Pitman ◽  
Long Le
Keyword(s):  
Debris Flows ◽  
Fluid Model ◽  
Solid Material ◽  
Fluid Inertia ◽  
Two Phase ◽  
Engineering Research ◽  
Mass Flows ◽  
Two Fluid Model ◽  
Two Fluid ◽  
Geophysical Mass Flows

Geophysical mass flows—debris flows, avalanches, landslides—can contain O (10 6 –10 10 ) m 3 or more of material, often a mixture of soil and rocks with a significant quantity of interstitial fluid. These flows can be tens of meters in depth and hundreds of meters in length. The range of scales and the rheology of this mixture presents significant modelling and computational challenges. This paper describes a depth-averaged ‘thin layer’ model of geophysical mass flows containing a mixture of solid material and fluid. The model is derived from a ‘two-phase’ or ‘two-fluid’ system of equations commonly used in engineering research. Phenomenological modelling and depth averaging combine to yield a tractable set of equations, a hyperbolic system that describes the motion of the two constituent phases. If the fluid inertia is small, a reduced model system that is easier to solve may be derived.

scholarly journals Catalytic Cracking of Heavy Oil from Waste Plastic in Tapered Circulating Fluidized Bed Riser Reactor

2020 ◽  
Vol 141 ◽  
pp. 01012
Author(s):  
Parinya Khongprom ◽  
Thanapat Whansungnoen ◽  
Permsak Pienduangsri ◽  
Waritnan Wanchan ◽  
Sunun Limtrakul
Keyword(s):  
Fluidized Bed ◽  
Heavy Oil ◽  
Catalytic Cracking ◽  
Circulating Fluidized Bed ◽  
Fluid Model ◽  
Plastic Waste ◽  
Hydrodynamic Behavior ◽  
Continuous Increase ◽  
Waste Plastic ◽  
Two Fluid Model

Because of the continuous increase in the amount of plastic waste, catalytic cracking is an interesting method that could be used to convert heavy oil from thermal cracking of plastic waste into fuel. The objective of this study was to investigate the hydrodynamic behavior and the performance of catalytic cracking of heavy oil in a circulating fluidized bed reactor using computational fluid dynamics. The two– fluid model incorporated with the kinetic theory of granular flow was applied to predict the hydrodynamic behavior with a reactive flow. Three reactor geometries were studied, which included a conventional riser, tapered–out riser, and tapered–in riser. The four–lump kinetic model was used to describe the catalytic cracking of heavy oil from waste plastic. A core–annulus flow pattern was found in the three reactor geometries. The solid fraction distribution of the tapered reactor was found to be more uniform than that of the conventional riser. The tapered–in riser showed the highest heavy oil conversion with the lowest gasoline selectivity. However, the heavy oil conversion and gasoline selectivity of the conventional and tapered–out reactors were not significantly different.

scholarly journals CFD Simulation of Polydispersed Bubbly Two-Phase Flow around an Obstacle

2009 ◽  
Vol 2009 ◽  
pp. 1-12 ◽  
Author(s):  
E. Krepper ◽  
P. Ruyer ◽  
M. Beyer ◽  
D. Lucas ◽  
H.-M. Prasser ◽  
...  
Keyword(s):  
Size Distribution ◽  
Cfd Simulation ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Size Distribution Function ◽  
Phase Flow ◽  
Two Phase ◽  
Ansys Cfx ◽  
Two Fluid Model ◽  
Drag And Lift

This paper concerns the model of a polydispersed bubble population in the frame of an ensemble averaged two-phase flow formulation. The ability of the moment density approach to represent bubble population size distribution within a multi-dimensional CFD code based on the two-fluid model is studied. Two different methods describing the polydispersion are presented: (i) a moment density method, developed at IRSN, to model the bubble size distribution function and (ii) a population balance method considering several different velocity fields of the gaseous phase. The first method is implemented in the Neptune_CFD code, whereas the second method is implemented in the CFD code ANSYS/CFX. Both methods consider coalescence and breakup phenomena and momentum interphase transfers related to drag and lift forces. Air-water bubbly flows in a vertical pipe with obstacle of the TOPFLOW experiments series performed at FZD are then used as simulations test cases. The numerical results, obtained with Neptune_CFD and with ANSYS/CFX, allow attesting the validity of the approaches. Perspectives concerning the improvement of the models, their validation, as well as the extension of their applicability range are discussed.

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