Author: Jianxun Deng
Publisher:
ISBN:
Category : Fluidization
Languages : en
Pages : 278

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Book Description

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

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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: Wen-Ching Yang
Publisher: CRC Press
ISBN: 0824748360
Category : Science
Languages : en
Pages : 873

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Book Description
This reference details particle characterization, dynamics, manufacturing, handling, and processing for the employment of multiphase reactors, as well as procedures in reactor scale-up and design for applications in the chemical, mineral, petroleum, power, cement and pharmaceuticals industries. The authors discuss flow through fixed beds, elutriation and entrainment, gas distributor and plenum design in fluidized beds, effect of internal tubes and baffles, general approaches to reactor design, applications for gasifiers and combustors, dilute phase pneumatic conveying, and applications for chemical production and processing. This is a valuable guide for chemists and engineers to use in their day-to-day work.

Author: J.R. Grace
Publisher: Springer Science & Business Media
ISBN: 9400900953
Category : Science
Languages : en
Pages : 599

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Book Description
Since the late 1970s there has been an explosion of industrial and academic interest in circulating fluidized beds. In part, the attention has arisen due to the environmental advantages associated with CFB (circulating . fluidized bed) combustion systems, the incorporation of riser reactors employing cir culating fluidized bed technology in petroleum refineries for fluid catalytic cracking and, to a lesser extent, the successes of CFB technology for calcina tion reactions and Fischer-Tropsch synthesis. In part, it was also the case that too much attention had been devoted to bubbling fluidized beds and it was time to move on to more complex and more advantageous regime,S of operation. Since 1980 a number of CFB processes have been commercialized. There have been five successful International Circulating Fluidized Bed Confer ences beginning in 1985, the most recent taking place in Beijing in May 1996. In addition, we have witnessed a host of other papers on CFB funda mentals and applications in journals and other archival publications. There have also been several review papers and books on specific CFB topics. However, there has been no comprehensive book reviewing the field and attempting to provide an overview of both fundamentals and applications. The purpose of this book is to fill this vacuum.

Author: Richard Dennis Lusk (Junior)
Publisher:
ISBN:
Category :
Languages : en
Pages : 190

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Book Description
A cold flow model circulating fluidized bed reactor was designed and built to determine any correlation that may exist between the percentage of fine bed material in the overall reactor inventory, and both the solids circulation rate as well as the riser axial particle distribution. It was determined that for Geldart group B particles (sand), there may be a direct relationship between an increase in the percentage of fine particles and an increase in the solids circulation rate for a given riser superficial velocity. There may also be a direct relationship between the percentage of fine particles and an increase in the overall solids concentration in the upper zones of the riser for a given riser superficial velocity. It is theorized that these effects are due to a reduction in the overall mean particle size of any particle clusters formed due to the increase of the percentage of fines.

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

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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 : Fluidization
Languages : en
Pages : 684

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Book Description

Author: P. Basu
Publisher: Elsevier
ISBN: 1483286347
Category : Science
Languages : en
Pages : 465

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Book Description
This volume focuses on the present status of circulating fluidized bed technology and provides design information not available elsewhere. Areas covered include combustion of fossil fuel, hydrodynamics, combustion and environmental pollution, design and operating experiences, heat transfer and hydrodynamics, and process applications.

Author: Prabir Basu
Publisher: Pergamon
ISBN:
Category : Science
Languages : en
Pages : 600

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Book Description
Circulating Fluidized Bed Technology II is a result of a series of science-related conferences in the 1980s. The text contains various studies, facts, and discussions on fluidized beds. The book begins by going through the rise and fall of circulating systems, specifically fluid dynamics. The chapter continues with a wider discussion of hydrodynamics, which includes its scales, particles, and different math formulas. In the several chapters that follow, a thorough study of fluidized beds and its subtopics are presented, which include particle behavior, combustion, heat transfer process, reactors, gas mixing, parameters, measurements, and characteristics. The variations of fluidized beds, including the multisolid, dual-column, and turbulent, are also given. The book serves as a very useful reference for undergraduates and postgraduates of physics, chemistry, and other related fields.

Author: Ethan James Brue
Publisher:
ISBN:
Category :
Languages : en
Pages : 296

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Book Description