3-D Modeling of Liquid Injection into Fluidized Beds

2004 ◽  
Vol 2 (1) ◽  
Author(s):  
Joachim Werther ◽  
Stefan Bruhns
Keyword(s):  
Fluidized Bed ◽  
Flow Structure ◽  
Three Dimensional ◽  
Fluidized Bed Reactors ◽  
Three Dimensional Model ◽  
Liquid Injection ◽  
Bubbling Fluidized Bed ◽  
Solids Mixing ◽  
Semi Empirical ◽  
Bubble Splitting

A three-dimensional model has been developed to describe the injection of liquid reactants into fluidized bed reactors operating in the bubbling fluidized bed regime. The model considers the processes of liquid transport and evaporation in the vicinity of the point of injection. The underlying idea, which is supported by previous measurements, is that the particles in the dense suspension phase are wetted by the liquid or gas-liquid spray. The wetted particles are subsequently dried while they are following the gross solids circulation within the bed. The model considers the flow structure of the bubbling fluidized bed and the solids mixing with the aid of a hybrid model which combines semi-empirical models for bubble growth by coalescence and for bubble splitting with a CFD approach for the continuous emulsion phase surrounding the bubbles. Submodels for heat and mass transfer are used to describe the temperature and concentration fields in the vicinity of the injection nozzle and the drying process of the wetted particles with the resulting release of the vaporized injection liquid. The model was validated separately against flow structure measurements, solids tracer measurements and experiments with the injection of water and ethanol, respectively, into beds of FCC particles.

A Three-Dimensional Model Frame for Modelling Combustion and Gasification in Circulating Fluidized Bed Furnaces

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Kari Myöhänen ◽  
Timo Hyppänen
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Large Scale ◽  
Circulating Fluidized Bed ◽  
Three Dimensional ◽  
Process Conditions ◽  
Three Dimensional Model ◽  
Macro Scale ◽  
Semi Empirical ◽  
Meso Scale

In a large-scale circulating fluidized bed furnace, the local feeding of fuel, air, and other input materials, and the limited mixing rate of different reactants produce spatially non-uniform process conditions. To simulate the real conditions, the furnace should be modelled three-dimensionally or the three-dimensional effects should be accounted for. The fluidized beds can be studied by different model approaches, ranging from micro-scale particle models and meso-scale two-fluid models to macro-scale engineering models. The fundamentals-oriented micro- and meso-scale models are not yet capable for practical comprehensive calculations of industrial scale circulating fluidized bed units, including modelling of reactions, attrition of particles, and heat transfer. The following paper introduces a three-dimensional semi-empirical steady state model for modelling combustion and gasification in circulating fluidized bed processes. The incorporated submodels include fluid dynamics of solids and gases, fuel combustion and limestone reactions, comminution of solid materials, homogeneous reactions, heat transfer within suspension and to surfaces, models for separators and external heat exchangers, and a model for nitrogen oxide chemistry. The model structure and the main features together with a sample calculation are described. A review of the currently used model approaches for fluidized bed systems at different scales is included to relate the presented model to other modelling field and to justify the need for semi-empirical modelling approach.

Three dimensional multi fluid modeling of Geldart B bubbling fluidized bed with complex inlet geometries

2017 ◽  
Vol 312 ◽  
pp. 89-102 ◽  
Author(s):  
Peter Ostermeier ◽  
Annelies Vandersickel ◽  
Stephan Gleis ◽  
Hartmut Spliethoff
Keyword(s):  
Fluidized Bed ◽  
Three Dimensional ◽  
Fluid Modeling ◽  
Bubbling Fluidized Bed

scholarly journals Three-dimensional numerical simulation of upflow bubbling fluidized bed in opaque tube under high flux solar heating

AIChE Journal ◽  
2018 ◽  
Vol 64 (11) ◽  
pp. 3857-3867 ◽  
Author(s):  
Hadrien Benoit ◽  
Renaud Ansart ◽  
Hervé Neau ◽  
Pablo Garcia Triñanes ◽  
Gilles Flamant ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Fluidized Bed ◽  
Three Dimensional ◽  
Solar Heating ◽  
High Flux ◽  
Bubbling Fluidized Bed

CFD-DEM Modeling of CO2 Capture using Alkali Metal-Based Sorbents in a Bubbling Fluidized Bed

2014 ◽  
Vol 12 (1) ◽  
pp. 441-449 ◽  
Author(s):  
Zhonglin Zhang ◽  
Daoyin Liu ◽  
Yaming Zhuang ◽  
Qingmin Meng ◽  
Xiaoping Chen
Keyword(s):  
Fluidized Bed ◽  
Gas Flow ◽  
Fluidized Bed Reactors ◽  
Solid Sorbents ◽  
Bubbling Fluidized Bed ◽  
Shrinking Core ◽  
Simulation And Experiment ◽  
Kinetics Simulation ◽  
Reaction Processes ◽  
Back Mixing

Abstract This paper describes a CFD-DEM modeling of CO2 capture using K2CO3 solid sorbents in a bubbling fluidized bed, which takes into heat transfer, hydrodynamics, and chemical reactions. Shrinking core model is applied in reaction kinetics. Simulation and experiment results of bed pressure drop and CO2 concentration in the reactor exit agree well. Instantaneous dynamics as well as time-averaged profiles indicate detailed characteristics of gas flow, particle motion, and chemical reaction processes. The simulation results show an obvious core-annular flow and strong back-mixing flow pattern. CO2 concentration decreases gradually along the bed height, while regards on the lateral distribution CO2 concentration near the wall is lower than that in the middle zone where gas passes through faster. The effect of bubbles on CO2 reaction is two-sided: it can promote mixing which strengthens reaction, while it can be a short pass of gas which is not beneficial to reaction. The simulation is helpful for further understanding and optimal design of fluidized bed reactors of CO2 capture.

Three-Dimensional Model of the Flow Structure in the Asynchronous Polar CD Ind during Magnetic Pole Switching

2021 ◽  
Vol 65 (5) ◽  
pp. 392-411
Author(s):  
A. V. Sobolev ◽  
A. G. Zhilkin ◽  
D. V. Bisikalo ◽  
D. A. H. Buckley
Keyword(s):  
Flow Structure ◽  
Three Dimensional ◽  
Dimensional Model ◽  
Magnetic Pole ◽  
Three Dimensional Model

scholarly journals A Mixing Behavior Study of Biomass Particles and Sands in Fluidized Bed Based on CFD-DEM Simulation

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1801 ◽  
Author(s):  
Heng Wang ◽  
Zhaoping Zhong
Keyword(s):  
Fluidized Bed ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Gas Velocity ◽  
Three Dimensional Model ◽  
Large Size ◽  
Behavior Study ◽  
Mixing Behavior ◽  
Computational Fluid Dynamics Cfd ◽  
Biomass Particles

The present paper studied the mixing characteristics of biomass and sands in a fluidized bed. A three dimensional model is calculated on the basis of computational fluid dynamics (CFD) and the discrete element method (DEM), while the lab-scale experiments under similar conditions are conducted. To investigate the mixing behavior of biomass and sands, particle distribution, particles time averaged kinetic motion and the Lacey index are analyzed and the effects of gas velocity and biomass size are discussed. Gas velocity provides the basic motion for particle movement and biomass particles gain a lot more kinetic motion than sands due to their large size. The biomass mixing process in a horizontal direction is more sensitive to gas velocity than in a vertical direction. Biomass size could slightly affect the mixing quality and a well mixing in fluidized bed could be reached if the size of biomass to sands is smaller than 4 times.

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