2 edition of flow behaviour of shallow fluidised beds. found in the catalog.
flow behaviour of shallow fluidised beds.
Stuart James McGuigan
by University of Aston in Birmingham, Dept. of Mechanical Engineering in Birmingham
Written in English
|Series||Ph.D. thesis 1974|
A numerical study was carried out to explore the hydrodynamic behavior of gas-solid flow in a 2D turbulent fluidized bed. The gas-solid flow was simulated by mean of an Eulerian-Eulerian two fluid. A fluidized bed reactor (FBR) is a type of reactor device that can be used to carry out a variety of multiphase chemical reactions. In this type of reactor, a fluid (gas or liquid) is passed through a solid granular material (usually a catalyst possibly shaped as tiny spheres) at high enough speeds to suspend the solid and cause it to behave as though it were a fluid.
The fluidized bed offers a number of advantages over most other methods of contacting, in particular high rates of heat transfer, temperature uniformity and solids mobility. Among the disadvantages are particle losses by entrainment, attrition of solids, limited reactor efficiency due to gas bypassing and gas and solids backmixing, and. The present study provides a deeply analysis of the flow behavior of bubbling fluidized beds with fine particles in two- (2D) and three-dimensional (3D) conditions, and computational fluid dynamics (CFD) simulations of agglomerates fluidization are carried out coupled with the modified agglomerate-force balance model, correspondingly. The experimental results indicate that the fluidized bed.
Homsy G.M. () Aspects of Flow and Mixing Behavior in Fluidized Beds. In: Guyon E., Nadal JP., Pomeau Y. (eds) Disorder and Mixing. NATO ASI Series (Series E: Applied Sciences), vol This paper reviews recent advances in our understanding of the origin and hierarchy of organized flow structures in fluidized beds, distinction between bubbling and nonbubbling systems, and stages of bubble evolution. Experimental data and theory suggest that, at high particle concentrations, the particle-phase pressure arising from flow-induced velocity fluctuations decreases with increasing.
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The flow behaviour of shallow gas-fluidised beds was studied. experimentally using a rotational viscometer, and an inclined open channel. Initially, tests were carried out with the viscometer in order to establish qualitative trends in the flow properties of a variety of materials over a Author: Stuart J.
McGuigan. perforated or porous plate. In the case of fluidized bed coating, air is passed through a bed of polymer particles. When the frictional force acting on the particles, or pressure drop, of the flowing air through the bed equals or exceeds the weight of the bed, the powder particles become suspended and the bed exhibits liquid-like Size: 2MB.
mass and heat transfer, and particularly in the case of fluidized beds, catalytic chemical reactions. You will find a good deal of information about flow through packed and fluidized beds in the book by McCabe, Smith, and Harriott (1) and Perry’s Handbook (2).
Here, only a brief summary is given. First, let us consider flow through a packed Size: 44KB. Circulating Fluidized Bed Technology II is a result of a series of science-related conferences in the s. 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 Edition: 1. The fluid dynamics behavior of shallow fluidized and vibrofluidized beds operating with fresh leaves was investigated with the aim of exploring drying applications in a modified conveyor belt (MCB) system, which may be operated in a fixed- or fluidized-bed by: Fluidized beds are widely used in industry for mixing solid particles with gases or liquids.
In most industrial applications, a fluidized bed consists of a vertically-oriented column filled with granular material, and a fluid (gas or liquid) is pumped upward through a distributor at the bottom of the bed. The characteristics of the behaviour of the particles in a liquid fluidised bed in which the influence of the bubbles of fluid is small, depends at a particular liquid flowrate, on the size and size range of the particles.
Two types of behaviour can exist: 1. The particles may behave in a particulate manner with size segregation occurring such that the size of the particles and also the. In this phase, the bed can be considered fluidised because a heavier object sinks in the bed, and particles smoothly flow out when a weir built on the bed wall is opened.
In the swirling mode, the free surface of the bed resembles somewhat that of a rotating fluid, with a higher bed height at the wall than in the centre of the bed.
Four flow patterns, which are named as patterns A–D, were observed in this study as shown inFig. Patterns A, B and D were observed when the bed material was – glass beads and the.
Understanding how a fluidized bed as a multiphase flow system operates will improve its capabilities and operations.
Minimum fluidization velocity and local gas holdup are important parameters used to characterize the hydrodynamic behavior of a material inside the fluidized bed. Due to the opaque nature of a fluidized bed system, noninvasive X-ray. Pioneering CFD work on pulsed fluidized beds was performed by Wang and Rhodes.
They used the discrete element method to predict the fluidization behavior of a fluidized bed subjected to square-wave and sinusoidal pulsed flow in a bed contain spherical particles of diameter μm and density kg/m 3.
Profiles of bed pressure. The prototype consists of an indirect heating shallow cross-flow fluidized-bed reactor-receiver. It is composed of 4 compartments in series in which the particles are thermally treated with solar power in order to drive the endothermic calcination reaction.
The results of the experimental study of the dynamics of a shallow fluidized bed are reported. The behavior of granular material is controlled by the interplay of two factors--levitation due to. Shallow fluidized beds (SFB) are studied in this paper as a paradigm for deep fluidized beds.
We take advantage of their much simpler behavior to analyze their dynamics with a one-dimensional. The development of a mechanism for gas-particle heat transfer in shallow fluidised beds of large particles. Chemical Engineering Science32 (1), DOI: /(77) S.S.E.H. Elnashaie. Multiplicity of the steady in the fluidized bed reactors—III.
Understanding hydrodynamics of liquid−solid fluidized beds is crucial in proper scale-up and design of these reactors. Computational fluid dynamics (CFD) models have shown promise in gaining this understanding.
In this paper, a two-dimensional CFD model, using an Eulerian−Eulerian two-fluid model incorporating the kinetic theory of granular flow, is used to describe the liquid−solid two.
The fluid dynamics behavior of shallow fluidized and vibrofluidized beds operating with fresh leaves was investigated with the aim of exploring drying applications in a modified conveyor belt (MCB. Fluidized Beds Fluidization occurs when a gas or liquid is forced to flow vertically through a bed of particles at such a rate that the buoyed weight of the particles is completely supported by the drag force imposed by the fluid.
Abstract. A physical model of a steady jet discharging into a fluidized bed in a vertical direction is examined on the example of plane flow, and the quantities characterizing the exchange of particles and the fluid phase between the jet and the bed are estimated.
Some applications of swirling fluidized beds include drying and combustion processes using Geldart type D particles (Mohideen et al., ).
In a swirling fluidized bed, the bed height is an important factor in determining the bed behaviour. A shallow bed usually swirls as a single mass, whereas a deep bed behaves differently. The fluidization behavior of a binary mixture of Geldart D type particles in a shallow vibrated gas-fluidized bed (VFB) was systematically studied by using a high-speed dynamic camera.
This study drew a comparison between the fluidization of a VFB and a conventional gas-fluidized bed .Hydrodynamic characteristics among different flow regimes of gas fluidized beds are compared on the basis of experiments with fluidized catalytic cracking particles in a mm diameter riser.
Pressure and local voidage fluctuations were analyzed using both statistical and chaotic tools. The standard deviations of local voidage fluctuations are much lower in a high-density circulating.A fluidized bed is a physical phenomenon occurring when a quantity of a solid particulate substance (usually present in a holding vessel) is placed under appropriate conditions to cause a solid/fluid mixture to behave as a is usually achieved by the introduction of pressurized fluid through the particulate medium.
This results in the medium then having many properties and.