Solid-phase temperature in the combustion of carbon under fluidized-bed conditions

1978 ◽  
Vol 35 (1) ◽  
pp. 846-848
Author(s):  
A. A. Belyaev ◽  
G. N. Delyagin ◽  
V. G. Slutskii
Keyword(s):  
Fluidized Bed ◽  
Solid Phase ◽  
Phase Temperature

Solid to Gas Temperature Gradient in a Microwave Fluidized Bed

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Zeljko Pajkic ◽  
Achim Schmidt ◽  
Thorsten Gerdes ◽  
Monika Willert-Porada
Keyword(s):  
Fluidized Bed ◽  
Room Temperature ◽  
Materials Science ◽  
Solid Phase ◽  
Reaction Engineering ◽  
Gas Temperature ◽  
Science And Engineering ◽  
Materials Science And Engineering ◽  
Phase Temperature ◽  
Two Phases

Convective heat transfer from solid to gas was investigated in a microwave heated fluidized bed and compared to an identical conventionally heated bed. Fluidizing gas was fed at room temperature and heated in contact with the bed solid phase. Solid phase temperature was varied in range of 300-600°C. Temperature difference of the two phases and heat loss by gas stream were measured in both heating types and discussed regarding chemical reaction engineering and energy efficiency. Advantages of microwave heating in such systems were elaborated with an outlook to perspective applications of the process in field of materials science and engineering.

scholarly journals Effect of Wall Heat Transfer on the Fluidization Process

2021 ◽  
Vol 39 (2) ◽  
pp. 615-620
Author(s):  
Huda Ridha‏ ◽  
Mohammed Ghalib Al-Azawy
Keyword(s):  
Fluidized Bed ◽  
Solid Phase ◽  
Solid Particles ◽  
Superficial Velocity ◽  
Working Fluid ◽  
Aluminum Particles ◽  
Ansys Fluent ◽  
Computational Fluid Dynamics Cfd ◽  
Phase Temperature ◽  
Fluidization Process

The fluidized bed and the fluidization process and characteristics were studied in this paper numerically using Computational Fluid Dynamics (CFD) Ansys Fluent 15.0. Constant temperature was applied to both sides of the two-dimensional fluidized bed geometry. The superficial velocity of the working fluid ranged amid (0.08 – 0.5 m/s) and the initial height of the solid particles changed amid (0.05, 0.1, 0.2 m). Aluminum particles and water was used as working materials within the fluidized bed. The model used for the investigations was validated using Ngoh and Lim research results. The results showed that the fluidization head increases as the water inlet superficial velocity increases. As well as when the water inlet superficial velocity increases, the average solid phase temperature increases.

3D Numerical Simulation of Polydisperse Pressurized Gas-Solid Fluidized Bed

2011 ◽  
Author(s):  
P. Fede ◽  
O. Simonin ◽  
I. Ghouila
Keyword(s):  
Numerical Simulation ◽  
Fluidized Bed ◽  
Ethylene Polymerization ◽  
Solid Phase ◽  
Three Dimensional ◽  
Gas Velocity ◽  
Particle Segregation ◽  
3D Numerical Simulation ◽  
Model Predictions ◽  
The Mean

Three dimensional unsteady numerical simulations of dense pressurized polydisperse fluidized bed have been carried out. The geometry is a medium-scale industrial pilot for ethylene polymerization. The numerical simulation have been performed with a polydisperse collision model. The consistency of the polydisperse model predictions with the monodisperse ones is shown. The results show that the pressure distribution and the mean vertical gas velocity are not modified by polydispersion of the solid phase. In contrast, the solid particle species are not identically distributed in the fluidized bed indicating the presence of particle segregation.

scholarly journals Comparison of solid phase closure models in Eulerian-Eulerian simulations of a circulating fluidized bed riser

2019 ◽  
Vol 195 ◽  
pp. 39-50 ◽  
Author(s):  
Markku Nikku ◽  
Alexander Daikeler ◽  
Alexander Stroh ◽  
Kari Myöhänen
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Solid Phase ◽  
Closure Models

scholarly journals Experimental and Theoretical Study of the Axial Distribution of Solid Phase Particles in a Fluidized Bed

2021 ◽  
Vol 64 (4) ◽  
pp. 349-362
Author(s):  
A. V. Mitrofanov ◽  
V. E. Mizonov ◽  
N. S. Shpeynova ◽  
S. V. Vasilevich ◽  
N. K. Kasatkina
Keyword(s):  
Fluidized Bed ◽  
Field Experiments ◽  
Solid Phase ◽  
Cell Model ◽  
Experimental Studies ◽  
Parametric Identification ◽  
Resistance Coefficient ◽  
Model Material ◽  
Spherical Particles ◽  
Axial Distribution

The article presents the results of computational and experimental studies of the distribution of a model material (plastic spherical particles with a size of 6 mm) along the height of a laboratory two-dimensional apparatus of the fluidized bed of the periodic principle of action. To experimentally determine the distribution of the solid phase over the height of the apparatus, digital photographs of the fluidized bed were taken, which were then analyzed using an algorithm that had been specially developed for this purpose. The algorithm involved splitting the image by height into separate rectangular areas, identifying the particles and counting their number in each of these areas. Numerical experiments were performed using the previously proposed one-dimensional cell model of the fluidization process, constructed on the basis of the mathematical apparatus of the theory of Markov chains with discrete space and time. The design scheme of the model assumes the spatial decomposition of the layer in height into individual elements of small finite sizes. Thus, the numerically obtained results qualitatively corresponded to the full-scale field experiment that had been set up. To ensure the quantitative reliability of the calculated forecasts, a parametric identification of the model was performed using known empirical dependencies to calculate the particle resistance coefficient and estimate the coefficient of their macrodiffusion. A comparison of the results of numerical and field experiments made us possible to identify the most productive empirical dependencies that correspond to the cellular scheme of modeling the process. The resulting physical and mathematical model has a high predictive efficiency and can be used for engineering calculations of devices with a fluidized bed, as well as for setting and solving problems of optimal control of technological processes in these devices for various target functions.

Dynamical modelling of an anaerobic digestion fluidized bed reactor

1997 ◽  
Vol 36 (5) ◽  
pp. 285-292 ◽  
Author(s):  
Benjamin Bonnet ◽  
Denis Dochain ◽  
Jean-Philippe Steyer
Keyword(s):  
Fluidized Bed ◽  
Solid Phase ◽  
Biofilm Reactor ◽  
Momentum Balance ◽  
Balance Equations ◽  
Biological Variables ◽  
Dynamical Simulation ◽  
Model Derivation ◽  
The Stability ◽  
Bed Expansion

One of the main difficulties in modelling a Fluidized Bed Biofilm Reactor (FBBR) is to take into account hydraulic phenomena (such as bed expansion) and its interactions with the biological variables. In this paper, we shall present a dynamical model of the process, analyse the stability of the hydrodynamics and illustrate its performances in simulation. A key feature of the model is that it combines mass balance of the process components with momentum balance equations in order to emphasise the different hydrodynamics of the liquid phase and of the solid phase, and the interactions between both phases. The model derivation finally leads to a set of partial differential equations (PDE). This model is intended to be used as a basis for the derivation of controllers and for dynamical simulation.

CFD Modelling of a Fluidized Bed Gasifier; Effects of Drag Model and Bed Heights

2014 ◽  
Vol 699 ◽  
pp. 730-735
Author(s):  
Kamariah Md Isa ◽  
Kahar Osman ◽  
Nik Rosli Abdullah ◽  
Azfarizal Mukhtar ◽  
Nor Fadzilah Othman
Keyword(s):  
Fluidized Bed ◽  
Volume Fraction ◽  
Solid Phase ◽  
Multiphase Model ◽  
Cfd Modelling ◽  
Drag Model ◽  
Bed Height ◽  
Representative Unit Cell ◽  
Fluidized Bed Gasifier ◽  
Drag Models

One of the unresolved issues in using the gasifier is the inability to determine the occurrence of the transition regime of fluidized bed. In modeling gas-solid phase, drag force is one of the main mechanisms for inter-phase momentum transfer. Thus, a simulation of fluidized bed was developed to study the effect of using various drag models over different bed height of H/D ratio such as 0.5, 1 and 2. A two dimensional model using Eulerian-Granular Multiphase Model (EGM) based on two fluid models have been used to simulate hydrodynamics of a bubbling fluidized beds. Gas-solid interactions are modeled via inter-phase of a drag model. The drag correlations of Gidaspow, Wen Yu, Syamlal-O'Brien, Hill Koch Ladd (HKL) and Representative Unit Cell (RUC) were implemented to simulate the interaction between phases. From this study, we found that different H/D ratio such as 0.5, 1 and 2 yields different volume fraction as increasing bed height slows kinetic transport of particle sand to the upper side of the bed. Besides that, different H/D ratio also resulted in different velocity vector. The results also show that Wen Yu and Syamlal-O'Brien are sufficient enough in detecting the change from one regime to another regardless of the bed height.

The Phase Transformations during Fluidized-Bed Combustion of Biomass

2013 ◽  
Vol 419 ◽  
pp. 366-369 ◽  
Author(s):  
Hai Peng Teng ◽  
Bin Yang ◽  
Bin Liang
Keyword(s):  
Gas Phase ◽  
Fluidized Bed ◽  
Solid Phase ◽  
Fluidized Bed Reactor ◽  
Biomass Combustion ◽  
Material Surface ◽  
Fluidized Bed Combustion ◽  
Biomass Ash ◽  
Equilibrium Modeling ◽  
Bed Material

FactSage6.1 was used to study the phase transformation at high temperature when biomass combustion in a fluidized bed reactor. The results show that eutectic was formed during the reaction process, the eutectics are formed mainly by the reaction between the silica in bed particles and the alkali species in biomass ash. The solid phase transformed to melt layer on the surface of sands particle mainly contains potassium, some calcium and magnesium, and also a few phosphorus and chlorine are found in the melt layer. The result utilizing FactSage equilibrium modeling shown that the distribution ratio of potassium in the gas phase increased with the increase of temperature, moreover, the melt of bed material surface increased when defluidized occurred.

Study on Black Liquor Low-temperature Gasification in Fluidized Bed by Eulerian Multiphase Computationally Fluid Dynamics Modeling

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Weiling Li ◽  
Wenqi Zhong ◽  
Baosheng Jin ◽  
Rui Xiao ◽  
Yingjuan Shao ◽  
...  
Keyword(s):  
Low Temperature ◽  
Fluidized Bed ◽  
Reaction Rate ◽  
Solid Phase ◽  
Heterogeneous Reaction ◽  
Black Liquor ◽  
Molar Fraction ◽  
Reaction Rates ◽  
Operating Conditions ◽  
Heterogeneous Reactions

Abstract A three-dimensional Eulerian multiphase based computational model was developed to simulate the black liquor gasification processes in a fluidized bed gasifier (FBG) at low temperature. The standard k-e model and kinetic theory of granular model were used to simulate the gas phase and solid phase, respectively. Black liquor pyrolysis, homogeneous reactions and heterogeneous reactions were taken into account in chemical model. The reaction rates of homogeneous and heterogeneous reaction were determined by Arrhenius–Eddy dissipation reaction rate and kinetic reaction rate. Simulations were carried out at four different operating conditions, i.e. reactor temperature was kept at 550 degree centigrade or 600 degree centigrade, and nitrogen or air was used as fluidizing medium. The calculated results were in well agreement with the experiment used as calibration. Base on the simulation, gas-sold flow patterns and gas species molar fraction distributions were obtained, the relationship of gas composition profiles with the temperature and the fluidizing media were discussed.

Analysis of Solid Structures and Stresses in a Gas Fluidized Bed

2007 ◽  
Author(s):  
Jin Sun ◽  
Francine Battaglia
Keyword(s):  
Kinetic Theory ◽  
Normal Stress ◽  
Fluidized Bed ◽  
Volume Fraction ◽  
Solid Phase ◽  
Coarse Graining ◽  
Contact Forces ◽  
Normal Contact ◽  
Stress Components ◽  
Force Network

Structures and stresses for the solid phase in a gas-solid fluidized bed are analyzed using results from hybrid simulations. The hybrid method couples the discrete element method (DEM) for particle dynamics with the averaged two-fluid (TF) equations for the gas phase. The coupling between the two phases is modeled using an interphase momentum transfer term. Structure information is characterized using force network size distribution, which shows no large force network existing in the fluidized bed. The normal contact forces have an exponentially decaying distribution. Solid phase continuum fields (local volume fraction, strain rate, stress tensor, and granular temperature) are computed using a coarse-graining process. The results show that the stress has difference in normal stress components. The collisional contribution is larger than the kinetic contribution and spatially correlated to force networks. Stresses are also computed using a kinetic theory stress model. It is demonstrated that the kinetic theory model predicts no difference in normal stress components and larger normal stresses than those computed from the coarse-graining process.

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