Consistency of circulating fluidized bed experimental data

1993 ◽  
Vol 32 (6) ◽  
pp. 1041-1045 ◽  
Author(s):  
S. Ouyang ◽  
O. E. Potter
Keyword(s):  
Experimental Data ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed

Applications of Feed-Forward Neural Network to Study Irregular-Shape Particle Effects on Hydrodynamics Behavior in a Liquid–Solid Circulating Fluidized Bed Riser

2013 ◽  
Vol 11 (1) ◽  
pp. 443-452 ◽  
Author(s):  
Shaikh Abdur Razzak
Keyword(s):  
Neural Network ◽  
Experimental Data ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Phase Distribution ◽  
Flow Behavior ◽  
Pilot Scale ◽  
Irregular Shape ◽  
Feed Forward Neural Network ◽  
Feed Forward

Abstract Feed-forward neural network (FFNN) modeling techniques are applied to study the flow behavior of different-size irregular-shape particles in a pilot scale liquid–solid circulating fluidized bed (LSCFB) riser. The adequacy of the developed model is examined by comparing the model predictions with experimental data obtained from the LSCFB using lava rocks (dmean 500 and 920 µm) and water as solids and liquid phases, respectively. Axial and radial solid holdup profiles are measured in the riser at four axial locations (H 1, 2, 3 and 3.8 m above the distributor) above the liquid distributor for different operating liquids. In the model training, the effects of various auxiliary and primary liquid velocities, superficial liquid velocities and superficial solid velocities on radial phase distribution at different axial positions are considered. For model validation along with other experimental parameters, dimensionless normalized superficial liquid velocities and net superficial liquid velocities are also introduced. The correlation coefficient values of the predicted output and the experimental data are found to be 0.95 and 0.94 for LR-500 and LR-920 particles, respectively which reflects the competency of the developed FFNN model.

Flow Regime Study of a Light Material in an Industrial Scale Cold Flow Circulating Fluidized Bed

2006 ◽  
Vol 128 (2) ◽  
pp. 129-134 ◽  
Author(s):  
Joseph S. Mei ◽  
Esmail R. Monazam ◽  
Lawrence J. Shadle
Keyword(s):  
Experimental Data ◽  
Mathematical Models ◽  
Flow Regime ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Density Ratio ◽  
Gas Velocity ◽  
Dense Phase ◽  
Empirical Correlations ◽  
Light Material

A series of experiments was conducted in the 0.3meter diameter circulating fluidized bed test facility at the National Energy Technology Laboratory (NETL) of the U. S. Department of Energy. The particle used in this study was a coarse, light material, cork, which has a particle density of 189kg∕m3 and a mean diameter of 812μm. Fluidizing this material in ambient air approximates the same gas-solids density ratio as coal and coal char in a pressurized gasifier. The purpose of this study is twofold. First, this study is to provide a better understanding on the fundamentals of flow regimes and their transitions. The second purpose of this study is to generate reliable data to validate the mathematical models, which are currently under development at NETL. Utilization of such coarse, light material can greatly facilitate the computation of these mathematical models. Furthermore, the ratio of density of cork to air under ambient conditions is similar to the density ratio of coal to gas at the gasification and pressurized fluidized bed combustion environment. This paper presents and discusses the data, which covered operating flow regime from dilute phase, fast fluidization, and to dense phase transport by varying the solid flux, Gs at a constant gas velocity, Ug. Data are presented by mapping the flow regime for coarse cork particles in a ΔP∕ΔL‐Gs‐Ug plot. The coarse cork particles exhibited different behavior than the published literature measurements on heavier materials such as alumina, sand, FCC, silica gel, etc. A stable operation can be obtained at a fixed riser gas velocity higher than the transport velocity, e.g., at Ug=3.2m∕s, even though the riser is operated within the fast fluidization flow regime. Depending upon the solids influx, the riser can also be operated at dilute phase or dense phase flow regimes. Experimental data were compared to empirical correlations in published literature for flow regime boundaries as well as solids fractions in the upper dilute and the lower dense regions for fast fluidization flow regime. Comparisons of measured data with these empirical correlations show rather poor agreements. These discrepancies, however, are not surprising since the correlations for these transitions were derived from experimental data of comparative heavier materials such as sands, FCC, iron ore, alumina, etc.

Prediction of Solid Recirculation Rate and Solid Volume Fraction in an Internally Circulating Fluidized Bed

2015 ◽  
Vol 12 (04) ◽  
pp. 1540005 ◽  
Author(s):  
Ravi Gujjula ◽  
Narasimha Mangadoddy
Keyword(s):  
Experimental Data ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Volume Fraction ◽  
Draft Tube ◽  
Numerical Study ◽  
Solid Particles ◽  
Granular Temperature ◽  
Solids Concentration ◽  
Drag Laws

This paper presents a numerical study of gas and solid flow in an internally circulating fluidized bed (ICFB). Two-fluid Eulerian model with kinetic theory of granular flow option for solid phase stress closure and various drag laws were used to predict the hydrodynamic behavior of ICFB. 2D and 3D geometries were used to run the simulations. The 2D simulation results by various drag laws show that the Arastoopour and Gibilaro drag models able to predict the fluidization dynamics in terms of flow patterns, void fractions and axial velocity fields close to the experimental data. The effect of superficial gas velocity, presence of draft tube on solid hold-up distribution, solid circulation pattern, and variations in gas bypassing fraction for the 3D ICFB are investigated. The mechanism governing the solid circulation and solids concentration in an ICFB has been explained based on gas and solid dynamics obtained from the simulations. Predicted total granular temperature distributions in the draft tube and annular zones qualitatively agree with experimental data. The total granular temperature tends to increase with increasing solids concentration in the dilute region (ε < 0.1) and decreases with an increase of solids concentration in the dense region (ε > 0.1). In the dense zone, the decreasing trend in the granular temperature is mainly due to the reduction of the mean free path of the solid particles.

Effect of Various Parameters on the Solids Holdup in a Liquid-Solid Circulating Fluidized Bed

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Natarajan Palani ◽  
Velraj Ramalingam ◽  
Seeniraj R.V.
Keyword(s):  
Experimental Data ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Liquid Flow ◽  
Circulating Fluidized Bed ◽  
Liquid Flow Rate ◽  
Tap Water ◽  
Solid Particles ◽  
Circulation Rate ◽  
Solids Holdup

A liquid-solid circulating fluidized bed (LSCFB) is operated at high liquid velocity, where particle entrainment is highly significant and between the conventional liquid fluidized bed and the dilute phase liquid transport regimes. In the present work, systematic experiments were carried out in a 0.094 m ID and 2.4 m height laboratory-scale liquid-solid circulating fluidized bed apparatus by using various solid particles and tap water as a fluidizing medium to study the hydrodynamics (axial solids holdup and solids circulation rate). The effects of operating parameters, i.e., primary liquid flow rate in the riser (jf), auxiliary liquid flow rate (ja), total liquid flow rate (jl), particle density (?s), particle diameter (dp) and solids feed pipe diameter (do) on the axial solids holdup distribution were analyzed from the experimental data. Finally, a correlation was developed from the experimental data to estimate average solid holdup in the riser, and it was compared with present experimental and available data in the literature. They agree well with a maximum root-mean-square deviation of 9.12 %.

A Model to Predict Radial Solids Holdup and Liquid Velocity Distributions in Liquid-Solid Circulating Fluidized Bed

2007 ◽  
Vol 2 (3) ◽  
Author(s):  
Natarajan Palani ◽  
Velraj R. ◽  
Seeniraj R.V.
Keyword(s):  
Experimental Data ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Liquid Velocity ◽  
Two Phase ◽  
Cross Sectional ◽  
Operating Variables ◽  
Solids Holdup ◽  
Cross Sectional Average ◽  
Good Agreement

A general expression which is useful for predicting the radial distributions or for analyzing and interpreting experimental data is derived for a liquid-solid circulating fluidized bed. The effect of both the radial liquid velocity and solids holdup distributions are taken into account in the analysis. Both effects are analyzed and are related to the operating variables of superficial liquid velocity, jl, superficial solids velocity, js, and cross-sectional average solids holdup. The results predicted by the analysis are compared with the experimental data obtained for various two-phase flow regimes, when different solids and bed dimensions are applied. The model predictions show good agreements with the experimental data and reasonable trends when different solids and bed dimensions are applied. Stronger non-uniformities in flow structures are found in larger size particles systems, with larger solids density and/or larger diameter columns. Radial solids holdup distribution is related with the cross-sectional average solids holdup. Good agreement with data and reasonable trends are observed.

Application of LS-SVM Control Model in Circulating FLuidized Bed Electric Power Generation Process

2012 ◽  
Vol 241-244 ◽  
pp. 1105-1108
Author(s):  
Ming Ming Gao ◽  
Ji Zhen Liu ◽  
Kai Yang Li ◽  
Yu Wen Zhu ◽  
Yong Zhou ◽  
...  
Keyword(s):  
Experimental Data ◽  
Power Generation ◽  
Electric Power ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Least Square ◽  
System Structure ◽  
Support Vector ◽  
Generation Process ◽  
Electric Power Generation

The model of circulating fluidized bed (CFB) electric power generation process based on dynamic method which needs a lot of parameters, but these parameters are usually not easy to get. A model method based on least square support vector machine (LS-SVM) which directly uses the experimental data is presented to overcome the weakness of mechanism model, and the system structure and algorithm are given. Compared with the experimental data, the simulation results show that this method has good performance and can provide control and optimization reference to the CFB electric power generation.

scholarly journals Development of Euler-Lagrangian Simulation of a Circulating Fluidized Bed Reactor for Coal Gasification

2019 ◽  
pp. 45 ◽  
Author(s):  
D. Tokmurzin ◽  
D. Adair
Keyword(s):  
Experimental Data ◽  
Fluidized Bed ◽  
Coal Gasification ◽  
Circulating Fluidized Bed ◽  
Fluidized Bed Reactor ◽  
Reaction Rates ◽  
Gas Composition ◽  
Particle In Cell ◽  
Lagrangian Simulation ◽  
Gasification Process

A Computational Particle Fluid Dynamics (CPFD) model based on the Multiphase Particle in Cell (MP-PIC) approach is used for Shubarkol coal gasification simulation in an atmospheric circulating fluidized bed reactor. The simulation is developed on a basis of experimental data available from a biomass gasification process. The cross-section diameter of the reactor riser is 200 mm and the height is 6500 mm. The Euler-Lagrangian simulation is validated using experimental data available in the literature and also compared with an Euler-Euler simulation. The gasification reactions kinetics model is improved, and homogenous and heterogeneous chemistry are described by reduced-chemistry, with the reaction rates solved numerically using volume-averaged chemistry. The simulations reveal gas composition, temperature, and pressure interdependencies along the height of the reactor. The product gas composition compares well with the experiment and the temperature profile demonstrate good consistency with the experiment. The developed model is used for a case study of Shubarkol coal gasification in the circulating fluidized bed reactor.

Modeling of Solid Fuel Combustion in Furnaces with a Circulating Fluidized Bed

2008 ◽  
Vol 39 (1) ◽  
pp. 65-78
Author(s):  
Yu. S. Teplitskii ◽  
V. A. Borodulya ◽  
V. I. Kovenskii ◽  
E. P. Nogotov
Keyword(s):  
Fluidized Bed ◽  
Solid Fuel ◽  
Circulating Fluidized Bed ◽  
Fuel Combustion ◽  
Solid Fuel Combustion
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