An Experimental and Numerical Study of the Velocity and Voidage Distribution in a Circulating Fluidized Bed Cold Model PDF Download

Author: Sirpa Kallio
Publisher:
ISBN: 9789516506701
Category :
Languages : en
Pages : 85

View

Book Description

Author:
Publisher:
ISBN:
Category : Coal gasification
Languages : en
Pages : 232

View

Book Description

Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 916

View

Book Description

Author: Elizabet Ananay Cruz Torres
Publisher:
ISBN:
Category : Fluidization
Languages : en
Pages : 584

View

Book Description

Author: Guodong Liu
Publisher:
ISBN:
Category : Science
Languages : en
Pages :

View

Book Description
Numerical simulation of voidage distributions and bed expansions is carried out in a liquid-solid fluidized bed in the present work. Effects of drag force models as well as virtual mass force and lift force are studied in the prediction of particle flow characteristics; simulated results indicated that both virtual mass force and lift force could not be neglected in liquid-solid fluidized bed. Different superficial velocities of liquid phase are also studied to investigate the effects of operating conditions on the distribution of particle concentration and velocities. The coefficient of restitution varied from 0.6 to 0.99, and the effects of radial distribution function models on granular pressure and granular temperature are also studied. Different drag models exhibit various particle velocity distributions, while the Gibilaro drag model failed in predicting the liquid-solid drag to some extent in this study. A comprehensive simulation model was proposed for predicting the two-phase flow characteristics in the liquid-solid fluidized bed. Predicted axial void fraction agrees qualitatively and quantitatively well with the experimental results in the literature.

Author: Prabir Basu
Publisher: Springer
ISBN: 3319061739
Category : Technology & Engineering
Languages : en
Pages : 370

View

Book Description
· Explains operation and scientific fundamentals of circulating fluidized bed (CFB) boilers · Outlines practical issues in industrial use · Teaches how to optimize design for maximum reliability and efficiency · Discusses operating and maintenance issues and how to troubleshoot them This book provides practicing engineers and students with insight into the design and operation of circulating fluidized bed (CFB) boilers through a combination of theoretical concepts and practical experience. An emphasis on combustion, hydrodynamics, heat transfer, and material issues illustrates these concepts with numerous examples from actual operating plants. The relevance of design and feed-stock parameters to the operation of a CFB boiler are also examined, along with their impacts on designs of mechanical components, including cyclones, air distributor grids, and solid recycle systems. This versatile resource explains how fluidized bed equipment works and how the basic principles of thermodynamics and fluid mechanics influence design, while providing insight into planning new projects, troubleshooting existing equipment, and appreciating the capabilities and limitations of the process. From hydrodynamics to construction and maintenance, the author covers all of the essential information needed to understand, design, operate, and maintain a complete fluidized bed system. It is a must for clean coal technology as well as for biomass power generation.

Author: Pang, Bo
Publisher: KIT Scientific Publishing
ISBN: 3731502194
Category :
Languages : en
Pages : 146

View

Book Description

Author: Shihui Zhou
Publisher:
ISBN:
Category :
Languages : en
Pages : 226

View

Book Description
A new theoretical approach to the modelling of the upward flow of gas-particle suspensions is presented. In this, the proposed theory is used to predict suspension concentration, radial gas and solids velocities, axial gas and solids velocities. This thesis provides a general expression for slip velocity between gas and solids phases. The equivalence of pressure gradient with suspension concentration is demonstrated. The experimentally observed existence of core-annulus flow structure, a rapidly- rising dilute core surrounded by a slowly-falling denser annulus adjacent to the pipe walls, in vertical risers is predicted by the theory. Sodium chloride tracer impulse injection was used to measure the longitudinal solids mixing in circulating fluidized bed risers of internal diameter 0.152 and 0.305m at superficial gas velocity from 2.8 to 5.0 m/s for mean solids circulation flux from 5.0 to 80 kg/m2s. The measured solids mixing data were satisfactorily described by a simple one-dimensional dispersion model which permits residence time distribution curves to be calculated directly from a knowledge of operating conditions. The degree of longitudinal solids mixing in the riser is found to decrease with increase in riser diameter. The measurement of instantaneous local temperature fluctuation traces and mean thermal boundary layers was conducted with a special probe for various operating conditions. A mechanism, in which eddying particle cloud swarms and gas packets are pictured as the receptors of heat, and relatively steady conduction of heat and unsteady random transport of heat play the principal roles in the wall-to-suspension heat transfer, is proposed and is analyzed mathematically. Overall heat transfer coefficients were measured on 0.180 m long heat transfer section in two scale cold model circulating fluidized bed risers at several temperature differences for ... powder at superfical gas velocity from 1.96 to 5.66 m/s, and for solids circulation fluxes up to 118.54 kg/m2s. Average heat transfer coefficients increase with suspension concentration which ranged from 0 to 86.09 kg/m3, and decrease with heat transfer temperature difference, Tw - Tb, which ranged from 12 to 121.5 degrees C Heat transfer coefficients are found to increase with riser diameter.

Author: Dimitri Gidaspow
Publisher: Elsevier
ISBN: 0080512267
Category : Science
Languages : en
Pages : 489

View

Book Description
Useful as a reference for engineers in industry and as an advanced level text for graduate engineering students, Multiphase Flow and Fluidization takes the reader beyond the theoretical to demonstrate how multiphase flow equations can be used to provide applied, practical, predictive solutions to industrial fluidization problems. Written to help advance progress in the emerging science of multiphase flow, this book begins with the development of the conservation laws and moves on through kinetic theory, clarifying many physical concepts (such as particulate viscosity and solids pressure) and introducing the new dependent variable--the volume fraction of the dispersed phase. Exercises at the end of each chapterare provided for further study and lead into applications not covered in the text itself. - Treats fluidization as a branch of transport phenomena - Demonstrates how to do transient, multidimensional simulation of multiphase processes - The first book to apply kinetic theory to flow of particulates - Is the only book to discuss numerical stability of multiphase equations and whether or not such equations are well-posed - Explains the origin of bubbles and the concept of critical granular flow - Presents clearly written exercises at the end of each chapter to facilitate understanding and further study

Author:
Publisher:
ISBN:
Category : Combustion engineering
Languages : en
Pages : 736

View

Book Description