The particle contacts in different particlefluid flow regimes, such as fixed, expanded and fluidized beds, in gas fluidization are investigated for group a and b powders by means of a combined. A typical example is fluidized bed cracking catalyst. Fluidization or fluidisation is a process similar to liquefaction whereby a granular material is converted from a static solidlike state to a dynamic fluidlike state. Mechanistic models for transitions between regimes of fluidization wenching yang research and development center wesllnghouse electrlc corporatlon pltlsburgh, p 15235 a introduction understanding the flow regime transitions is important because different flow regimes provide vastly different solid circulation patterns, solids and gas mixing rates, and thus the chemical reaction rates. It needs to be confirmed whether a fast xrt setup has sufficient temporal and spatial resolution for measurements in these regimes. The isothermal nature of fluidized beds and the high rates of heat and mass transfer are discussed.
Small gas voids and particle clusters dart to and fro. The simulation results were validated against experimental data. The application of nanopowder fluidization in practice is still limited, but a wide range of potential applications is foreseen. Your browser doesnt seem to have a pdf viewer, please download the pdf to view this.
Handbook of fluidization and fluidparticle systems. Mechanistic models for transitions between regimes of. The micromechanics of different flow regimes in gas fluidization of different powders has been examined based on the combined cfddem approach. Chemical engineering laboratory 3, ce 427 packed and fluidized bed experiment introduction packed and fluidized beds play a major role in many chemical engineering processes. This site is like a library, use search box in the widget to get ebook that you want. Study of fluidization regimes using openfoam computational. Hesketh1 prepared for the process fluid transport objectives 1 examine the flow regimes of a fluidized bed. Pdf flow regime identification in a fluidized bed combustion. Some first attempts have been made to apply computational fluid dynamics. Regular fluidization of these nanopowders can lead to two different types of fluidization. And you can get other different types of flow regimes,if you if you the fluidized bed is operated with the liquid and solid and also gas and liquid and solid. Evaluation of drag models for gassolid fluidization of geldart a particles in all flow regimes xi gao1, tingwen li1, 2, avik sarkar3, liqiang lu1, william a. Flow regime identification in a fluidized bed combustion reactor.
Fluidization regimes in different spouted bed apparatus. Nov 24, 2015 application of fluidization fluidized solids can be easily transferred between reactors. The intense mixing within a fluidized bed means that its temperature is uniform. Jun 18, 20 the particle contacts in different particlefluid flow regimes, such as fixed, expanded and fluidized beds, in gas fluidization are investigated for group a and b powders by means of a combined approach of computational fluid dynamics anddiscrete element method. Concepts in industrial fluidization 19 materials a are easy to fluidize. Transition velocities based on different measurement techniques. Understanding the different fluidization regimes allows a greater understanding of the physical nature of interaction for example, the residence time of a fluid reacting with a packed bed of reactant between the fluidized bed and the fluid causing the fluidization. Click download or read online button to get gas fluidization technology book now. The important properties of particles that relate to fluidization are discussed along with the different regimes that fluidized beds can exhibit. Regimes of fluidization for large particles american institute of. Spectral analysis of pressure fluctuations in fluidized beds under different regimes a numerical study 2 measured signal in order to create a reliable representation of the fluid dynamics of the system. Regimes of fluidization with increasing superficial gas velocity. To establish the connection between macroscopic and microscopic descriptions of complex particlefluid flows, focus is given to the. Fluidization regimes were studied for particles with the same density but different diameters.
Minimum fluidization velocity experimental determination and literature predictions and fluidized bed hydrodynamics special fluidized beds spouted bed, vibrofluidized beds fluidization regimes and transitions use of fluidized bed technology details later in the course. Feb 10, 2012 the agglomerates are typically a few hundred. Micromechanical modeling and analysis of different flow. The regimes including, namely slugging bed, jetinfluidized bed, spout fluidization, and intermediate, are simulated and validated against experiments. Fluidization of solid particles with liquids and with gases leads to vastly different phenomena of solids behavior, as shown in fig. Chapter 3 covers the basics of fluidization and provides a guide to tbe interrelationship between the different regimes of fluidization and gasparticle flow, providing a useful framework for tbe rest of the book. The types of flow regime that can be established in a fluidized bed depend on the parameters such as superficial gas velocity, particle.
New description of fluidization regimes american institute of. There is evidence that solids movement is different. University of groningen particle transport in fluidized. Pdf identification and characteristics of different flow regimes in a. This can cause confusion, and as has been shown in a recent paper i, it is responsible for some of the apparent contradictions and differences of opinion which. There is excellent heat transfer between a fluidized bed and heat exchangers immersed in the bed. Grace 1986a summarized the effects of particles properties and operating conditions on fluidization behavior and prepared a flow regime diagram. Unlike in the previous efforts, 3d dem is used in the present study in order to generate results more comparable to the reality. National energy technology laboratory, morgantown, wv, united states.
The effect of particle size distribution psd on the performance of a fluidized bed reactor was investigated in different hydrodynamic regimes. 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 highdensity circulating. Flow regimes in the two phase liquidsolid fluidized system mainly depends upon the liquid velocity. Characterization and classification of fluidization regimes by nonlinear analysis of pressure fluctuations. Numerical investigation of the effect of bed height on. Other minimum fluidization correlations exist, but eq.
Particulate fluidization is a condition when particles in a fluidized bed are. Fluidization regimes, international journal of multiphase. Numerical simulation for 4 different ratios of initial bed heights h to base diameter d, were performed. Relation between minimum fluidisation velocity and terminal settling velocity is discussed in this video and minimum fluidisation velocity is computed both analytically and experimentally. For other measurement techniques in fluidized beds. The particle diameters were selected based on geldarts classification of particles. The results show that the lattice boltzmann drag relation performs well in capturing characteristics of different gassolid flow. Fluidization can also be used to provide individual nps with a thin coating of another material and to mix two different species of nanopowder. Tbe text is organized into 18 chapters beginning with an introduction and a chapter on industrial applications. Evaluation of drag models for gassolid fluidization of. Effect of initial static bed height and liquid superficial. The point at which this occurs depends on the particle size and density. Thapa and others published flow regime identification. Fluidized beds with coarse particles have become more.
Smaller or lighter particles tend to experience smooth fluidization. Simulation of different gassolid flow regimes using a drag. Dec 23, 2015 stages of fluidization gas flow through the column from the blower to the drying chamber is characterized with increased gas flow as fixed bed, delayed bubbling, bubbling fluidization, slugging fluidization, turbulent fluidization, and fast fluidization and dilutes pneumatic conveying regimes as shown in fig 2. Our new crystalgraphics chart and diagram slides for powerpoint is a collection of over impressively designed datadriven chart and editable diagram s guaranteed to impress any audience. The flow regime diagram was further modified by kunii and levenspiel 1997. Ppt fluidization powerpoint presentation free to download. Hydrodynamic characteristics among different flow regimes of gas fluidized beds are compared on the basis of experiments with fluidized catalytic cracking particles in a 76. P is equal to the bed weight per unit crosssectional area, and the particle sphericity. Design of fluidized beds is introduced as are the various pieces of hardware needed. University of groningen particle transport in fluidized beds. Minimum fluidization velocity is one of the most important properties to characterize a bed, differentiating between a packed bed and a fluidized bed. Characteristics of gasfluidized beds in different flow regimes. When the gas velocities increase beyond the minimum fluidization velocity, bubbles can form.
The following conclusions can be drawn from the present study. Fluidization is the process where a bed of solid particles is transferred from a static solidlike state to a dynamic fluidlike state. Gas fluidization technology download ebook pdf, epub, tuebl. In liquid, fluidized beds, the flow regimes are limited as compared to gas fluidized beds. Such a transition, which occurs at upt, is known as choking. Segregation of a lower density tracer particle could be avoided at low liquid velocity by inclining the bed, thus, limiting power consumption of the pump and particle attrition. Fluidization regimes fluidization regimes 19971201 00. Characteristics of gasfluidized beds in different flow. Pdf characterization and classification of fluidization. Chart and diagram slides for powerpoint beautifully designed chart and diagram s for powerpoint with visually stunning graphics and animation effects. After the gas velocity surpasses a critical value, the particles become. Lion bulk handlings fluidization principle explained. Apf agglomerate particulate fluidization and abf agglomerate bubbling fluidization.
This process occurs when a fluid liquid or gas is passed up through the granular material. Fluidization regimes characterized using a fast xray. This principle is used in our bulk handling systems hiflow fluidization floor and airslides. Schematic is based upon a similar diagram appearing in perry et al. Fluidization and flow regimes of titaniferous solids. Contact analysis of different flow regimes in gas fluidization. These particles can be fluidized in a limited range of velocities in a regime similar to liquid fluidization i. Study of fluidized bed regimes using computational particle. Particulate fluidization definition and meaning collins. The second row of insets represents improved fluidization through the use of fine, smooth, graded particles, for which the full spectrum of fluidization regimes can be realized. Fluidized beds typically are more complex to design, build, and operate than other types of reactors, such as packedbed and stirredtank reactors. The objective of this paper is to characterize the fluidization regime transitions using. Fluidization regimes in different spouted bed apparatus constructions article in chemical engineering and processing 468.
30 1340 826 1033 462 163 547 82 1250 361 1040 1255 394 1251 1549 816 441 692 1406 536 1481 1439 1008 234 457 471 1287 1506 441 1080 593 735 1406 1220 927 352 1315 901 145 1431 1415 799 856