Large Particle Fluidization--a Photographic Study of a Two Dimensional Fluidized Bed PDF Download

Author: Michael William Ferrell
Publisher:
ISBN:
Category :
Languages : en
Pages : 114

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Author: Adonis C. Stephanakis
Publisher:
ISBN:
Category : Fluidization
Languages : en
Pages : 190

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Observation shows that bubbles in large particle fluidized beds behave quite differently from beds of fine particles. They expand and can grow faster than they rise. Bubbles in fine particle beds seem to grow primarily by coalescence, while in large particle beds they are observed to grow mainly without coalescence. The aim of this study was to gain a better insight into bubble behavior in fluidized beds of intermediate and large particles (particle diameter greater than 0.4 mm), and understand the cause of the observed bubble growth. In the theoretical part of this work it is shown that emulsion voidage invariability, incompressible viscous gas flow and potential solids flow assumed by existing theoretical two-phase models cannot account for the observed gas accumulation within bubbles. A simplified theoretical form for the gas accumulation rate in a cylindrical bubble is developed. It is based on different areas of gas inflow and outflow at the bubble boundary, and on the fact that the emulsion voidages above and below the bubble are different. It was shown that voidage variations in the emulsion phase around a bubble are important to bubble growth considerations. The experimental cases analyzed for single growing two dimensional bubbles indicate a higher voidage at the wake region, than the voidage at the nose of the bubble. It was found that a relatively small difference in emulsion voidage above and below the bubble can cause significant gas accumulation within the bubble reaching values comparable to the gas throughflow. Finally the movement of bubbles in the vicinity of an immersed tube and pressure-time curves representing the slow bubble and rapid bubble growth regime, and the transition range are analyzed in order to identify important bubble behavior characteristics. An experimental set up was developed making possible simultaneous permanent recording of the two-dimensional bubble behavior and instantaneous pressure data acquisition at multiple locations in an area under study. Lapsed cinematography and a special circuit activating the data acquisition system was used. The experimental set up enabled the collection of a large amount of data which gave valuable information about fluid dynamic behavior in the vicinity of an immersed tube. Experiments were performed at atmospheric pressure and room temperature in a two-dimensional fluidized bed with an immersed 50.8.mm (2 in) in diameter internal located at a height 0.35 m above the distributor plate. Glass, sand and dolomite particles with mean surface particle diameters of 0.65 to 2.6 mm were used. Superficial air velocities used spanned a region from well below minimum fluidization conditions to 2.82 m/s.

Author: Arvind Chetty
Publisher:
ISBN:
Category : Fluidization
Languages : en
Pages : 124

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Author: Wen-Ching Yang
Publisher: CRC Press
ISBN: 0203912748
Category : Science
Languages : en
Pages : 876

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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: Yong-Chil Seo
Publisher:
ISBN:
Category :
Languages : en
Pages : 176

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Author: Baldev Singh
Publisher:
ISBN:
Category : Fluidization
Languages : en
Pages :

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Author: J G Yates
Publisher: Butterworth-Heinemann
ISBN: 1483162761
Category : Science
Languages : en
Pages : 237

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Fundamentals of Fluidized-bed Chemical Processes presents a survey of the design, operation, and chemical processes of fluidized-bed reactors. The book is composed of five chapters. The first chapter examines the basic physics of gas-solid fluidization. The second chapter shows how the physics of gas-solid fluidization may be combined with chemical kinetics to generate models of fluidized-bed reactors. Chapters 3 and 4 deal with two major applications of gas-solid fluidization, the Fluidized Catalytic Cracking process and the combustion and gasification of coal. The final chapter analyzes other processes used in the production of chemicals such as phthalic anhydride, acrylonitrile, and compounds of uranium. Undergraduate and postgraduate students of chemical engineering, engineers, chemists, and scientists will find this text useful.

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

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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: Tom Wytrwat
Publisher: Cuvillier Verlag
ISBN: 3736965710
Category : Technology & Engineering
Languages : en
Pages : 200

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An in-depth experimental study of the fluid dynamics of turbulent fluidized beds with particles of Geldart’s Group B was carried out. For this purpose, fluidization behavior was investigated in different fluidized bed plants having diameters in the range of 0.05 m to 1 m. Pressure fluctuation analysis has been used as an identification tool for the turbulent fluidized bed regime. Different fluidization conditions have been investigated by variation of the fluidized bed properties, the bed material properties, and the gas properties. Based on the measured data, a correlation predicting the transition velocity from bubbling to turbulent fluidization is introduced. To investigate the local flow structure, capacitance probe measurements have been carried out. Using this measurement technique, local solids concentrations and properties of rising bubbles have been determined and analyzed. Finally, an empiric fluid dynamic model was developed using the local measurement data. It is mainly based on capacitance probe measurements and shows high accuracy in comparison to pressure data.

Author: Yat On Chong
Publisher:
ISBN:
Category : Fluidization
Languages : en
Pages : 286

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