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Investigation On A Gas Solid Fluidized Bed Hydrodynamics Using A Non Intrusive Technology To Visualize Flow Field
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Book Synopsis Investigation on a Gas-solid Fluidized Bed Hydrodynamics Using a Non-intrusive Technology to Visualize Flow Field by : Md. Rashedul Hasan Sarker
Download or read book Investigation on a Gas-solid Fluidized Bed Hydrodynamics Using a Non-intrusive Technology to Visualize Flow Field written by Md. Rashedul Hasan Sarker and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigation of Gas Solid Fluidized Bed Dynamics with Non-Spherical Particles by :
Download or read book Investigation of Gas Solid Fluidized Bed Dynamics with Non-Spherical Particles written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the largest challenges for 21st century is to fulfill global energy demand while also reducing detrimental impacts of energy generation and use on the environment. Gasification is a promising technology to meet the requirement of reduced emissions without compromising performance. Coal gasification is not an incinerating process; rather than burning coal completely a partial combustion takes place in the presence of steam and limited amounts of oxygen. In this controlled environment, a chemical reaction takes place to produce a mixture of clean synthetic gas. Gas-solid fluidized bed is one such type of gasification technology. During gasification, the mixing behavior of solid (coal) and gas and their flow patterns can be very complicated to understand. Many attempts have taken place in laboratory scale to understand bed hydrodynamics with spherical particles though in actual applications with coal, the particles are non-spherical. This issue drove the documented attempt presented here to investigate fluidized bed behavior using different ranges of non-spherical particles, as well as spherical. For this investigation, various parameters are controlled that included particle size, bed height, bed diameter and particle shape. Particles ranged from 355 μm to 1180 μm, bed diameter varied from 2 cm to 7 cm, two fluidized beds with diameters of 3.4 cm and 12.4 cm, for the spherical and non-spherical shaped particles that were taken into consideration. Pressure drop was measured with increasing superficial gas velocity. The velocity required in order to start to fluidize the particle is called the minimum fluidization velocity, which is one of the most important parameters to design and optimize within a gas-solid fluidized bed. This minimum fluidization velocity was monitored during investigation while observing variables factors and their effect on this velocity. From our investigation, it has been found that minimum fluidization velocity is independent of bed height for both spherical and non-spherical particles. Further, it decrease with decreasing particle size and decreases with decreasing bed diameter. Shadow sizing, a non-intrusive imaging and diagnostic technology, was also used to visualize flow fields inside fluidized beds for both spherical and non- spherical particles and to detect the particle sizes.
Book Synopsis Experimental Study of the Hydrodynamics and Cluster Formation in a Circulating Fluidized Bed by :
Download or read book Experimental Study of the Hydrodynamics and Cluster Formation in a Circulating Fluidized Bed written by and published by . This book was released on 1991 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: A novel non-invasive gas-solid flow measuring technique being developed and tested for studying the hydrodynamics inside the riser of a Circulating Fluidized Bed (CFB). First of the two aims of the overall program, namely, design, development and testing of the technique to characterize the particle and gas velocities in two-phase flows was accomplished in the past year. The fringe-model'' laser Doppler anemometry concept has been modified and extended by using particles coated with a fluorescent dye and introducing a narrow band pass filter in the receiving optics. The technique permits optical discrimination between the scattered light (laser wavelength from undyed particles) and the fluorescence emission (longer wavelength). Results from extensive testing of various dye-solvent combinations, counter processor settings, signal-to noise optimization and subsequent flow measurements in the test section have shown that the technique can effectively discriminate between two classes of particles--the smaller seed particles for the gas phase data and the larger bed particles. Use of a two-watt Argon-Ion laser assisted in the non-intrusive probing of the gas-solid flow and in enhancing the signal-to-noise ratio. An uncertainty analysis of LDA measurements is presented. Design of the cold flow CFB model, presently under fabrication, is outlined in this report. The Plexiglas CFB model will be employed for the riser core-annular flow studies using the fluorescence-emission based laser-Doppler anemometry. The results from this study will present a unique detailed description of the complex gas-solid behavior in the CFB riser.
Book Synopsis An Investigation on the Mixing Hydrodynamics of a Gas-solid Fluidized Bed by : Mario A. Ruvalcaba
Download or read book An Investigation on the Mixing Hydrodynamics of a Gas-solid Fluidized Bed written by Mario A. Ruvalcaba and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Simulation of the Hydrodynamic Behavior of a Gas-solid Fluidized Bed with and Without an Electric Field by : Forhad Md Hossain
Download or read book Numerical Simulation of the Hydrodynamic Behavior of a Gas-solid Fluidized Bed with and Without an Electric Field written by Forhad Md Hossain and published by . This book was released on 1998 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this investigation is to numerically predict the effect of an electric field on a two-dimensional gas-solid fluidized bed. The particles in the bed are taken to be of a uniform size and density forming the particulate phase with a gas (air) taken as the continuum phase. A hydrodynamic model of fluidization utilizes the principles of conservation of mass and momentum describing the multiphase flow equations along with the constitutive equations of gas-solid drag and solids stress. A two-dimensional unsteady-state computer code (K-Fix) was used to observe the effect of an electric field on the gas and solid velocities and the void fraction and pressure in the bed. Special case studies included that of a jet, a bubble, and two bubbles, with and without an electric field.
Book Synopsis Experimental Study of the Hydrodynamics and Cluster Formation in a Circulating Fluidized Bed. Annual Report, 1990 by :
Download or read book Experimental Study of the Hydrodynamics and Cluster Formation in a Circulating Fluidized Bed. Annual Report, 1990 written by and published by . This book was released on 1991 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: A novel non-invasive gas-solid flow measuring technique being developed and tested for studying the hydrodynamics inside the riser of a Circulating Fluidized Bed (CFB). First of the two aims of the overall program, namely, design, development and testing of the technique to characterize the particle and gas velocities in two-phase flows was accomplished in the past year. The f̀̀ringe-model ̀̀laser Doppler anemometry concept has been modified and extended by using particles coated with a fluorescent dye and introducing a narrow band pass filter in the receiving optics. The technique permits optical discrimination between the scattered light (laser wavelength from undyed particles) and the fluorescence emission (longer wavelength). Results from extensive testing of various dye-solvent combinations, counter processor settings, signal-to noise optimization and subsequent flow measurements in the test section have shown that the technique can effectively discriminate between two classes of particles--the smaller seed particles for the gas phase data and the larger bed particles. Use of a two-watt Argon-Ion laser assisted in the non-intrusive probing of the gas-solid flow and in enhancing the signal-to-noise ratio. An uncertainty analysis of LDA measurements is presented. Design of the cold flow CFB model, presently under fabrication, is outlined in this report. The Plexiglas CFB model will be employed for the riser core-annular flow studies using the fluorescence-emission based laser-Doppler anemometry. The results from this study will present a unique detailed description of the complex gas-solid behavior in the CFB riser.
Book Synopsis Hydrodynamics and Flow Structure, Gas and Solids Mixing Behavior, and Choking Phenomena in Gas-solid Fluidization by : Bing Du
Download or read book Hydrodynamics and Flow Structure, Gas and Solids Mixing Behavior, and Choking Phenomena in Gas-solid Fluidization written by Bing Du and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In this study, the dynamic flow behavior and gas and solids mixing behavior in the turbulent fluidized beds are investigated by using Electrical Capacitance Tomography (ECT) technique and tracer technique. The ECT study reveals that the time-averaged solids holdup distribution exhibits radial symmetry in the turbulent regime. The addition of 10% fine particles decreases the solids concentration in the emulsion phase. The flow behavior in the turbulent fluidized beds is not appreciably affected by the temperature up to 400 oC. More than one spiral motion of bubble swarms is observed in the bubbling regime for the 0.3 m ID fluidized bed. The gas and solids mixing behavior varies significantly with the flow regimes. A small quantity of fine particles is noted to drastically affect the gas and solids mixing behavior in the turbulent fluidized bed. For Group A particles, the flow in the bed transits from the dilute regime to the turbulent regime when the gas velocity is below Utr or the solids circulation rate is lower than Gs, tr. Such flow transition can be signified as the choking transition. For Group B particles, choking is initiated by the formation of the square-nosed slugs (0.05 m ID column) or the wall slugs (0.1 m ID CFB) when the gas velocity is below Utr or the solids circulation rate is lower than Gs, tr. When the gas velocity is above Utr or the solids circulation rate is higher than Gs, tr, choking is characterized by the formation of open slugs. These regime transitions are characterized as the choking transition. A model based on the movement of the solids blob at the center of the bed is developed to predict the critical lifetime of a solids blob in a circulating fluidized bed. The criterion for the occurrence of choking transition in a circulating fluidized bed for both Group A and Group B particles is given.
Book Synopsis Use of an Optical Probe to Study the Hydrodynamics of a Gas-solid Fluidized Bed by : Fouad Arib
Download or read book Use of an Optical Probe to Study the Hydrodynamics of a Gas-solid Fluidized Bed written by Fouad Arib and published by . This book was released on 1989 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Visual Study of Hydrodynamics in a Two-dimensional Gas-solid Fluidized Bed by : Lisa Nalani Freeman
Download or read book Visual Study of Hydrodynamics in a Two-dimensional Gas-solid Fluidized Bed written by Lisa Nalani Freeman and published by . This book was released on 1992 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrodynamic effects play important roles in fluidized bed combustion processes. Since the motion of "bubbles" is an important influence on fluidized bed heat transfer, a better understanding of their behavior is necessary for improving the design of fluidized bed boilers. Using a two-dimensional bed, silica sand particles were fluidized with air at room conditions. The bubbling bed was videotaped, and both qualitative and quantitative information were gathered. Bubble characteristics such as size, rise velocity and frequency were studied while particle size and superficial gas velocity were varied. Results were compared with some existing theories and other similar research. The effect of internal surfaces at several heights in the bed was also studied. General bubble behavior agreed well with descriptions from previous research, and the expected spherical-cap bubble shape was observed. Both bubble size and rise velocity increased with particle size and with fluid velocity. Bubble frequency increased with fluid velocity, but decreased with increasing particle size and height in the bed. These results agree with previous work done using optical probes to measure bubble characteristics. Comparisons of data with empirical models showed general agreement. The presence of internal surfaces had the effect of reducing the bubble size, rise velocity, and frequency, and also of reducing the influence of changing particle size and superficial velocity on the bed behavior.
Book Synopsis Experimental Investigations of Bed Hydrodynamics and Solids Elutriation from Gas-fluidized Beds by : Dilip G. Kathuria
Download or read book Experimental Investigations of Bed Hydrodynamics and Solids Elutriation from Gas-fluidized Beds written by Dilip G. Kathuria and published by . This book was released on 1986 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Theory and Simulation of Incipient Instability in Gas-solid Fluidization by : Kar Yang Look
Download or read book Theory and Simulation of Incipient Instability in Gas-solid Fluidization written by Kar Yang Look and published by . This book was released on 2006 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanism of incipient in gas-solid fluidized bed was investigated by using Computational Fluid Dynamics (CFD) simulation - FLUENT version 6.1.18. The Finite Volume Method (FVM) is employed to simulate the complex flow behaviours and heterogenous structure of the gas-solid fluidized bed. Fluidization of Geldart group A B and C particles were simulated. The formation and development of the plumes during incipient fluidization were studied. Different fluidization behaviours of Geldart group A, B and C particles were observed from the contours of gas volume fraction and velocity vector. The observation agreed well with characteristics and behaviours of particles in gas-solid fluidized bed as reported by Geldart (1973). A theory of transient instability adopted with the principles advanced by Tan and Thorpe (1992 and 1996) was proposed to calculate the theoretical transient Rayleigh number (Rac) for the onset of incipient instability. The mobilization of the particles occured once a critical value of transient Rayleigh number was exceeded. Different type of particles exhibit different Rac values. However, the Rac is almost independent of the superficial velocity. The incipient instability of gas-solid fluidized bed was first indentified when the initial stable air diffusion became distorted and particles began to move chaotically. The fluidization parameters such as gas volume fraction, bubble rise velocity and bed pressure drop were used to determine the critical time for onset of incipient instability. The simulated critical onset time (tc) and transient Rayleigh Number (Rac) for the incipient instability of gas-solid fluidized bed were then investigated. A correlation between Rac and permeability was derived, which provides a convenient and simple way to estimate the Rac. The predicted values of Rac were found to agree fairly with the literature data.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1981 with total page 1370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Book Synopsis Hydrodynamic Study of Three Phase Fluidized Beds by : Ravindra Gaikwad
Download or read book Hydrodynamic Study of Three Phase Fluidized Beds written by Ravindra Gaikwad and published by LAP Lambert Academic Publishing. This book was released on 2014-01-01 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: The general purpose of the experimental investigations described here has to study the hydrodynamic properties of gas-liquid fluidized beds. Gas -liquid fluidization of or three-phase fluidization is a chemical engineering operation where all the three phases are brought into contact with each other. This contact is brought about by passing the gas and liquid trough the bed of solids. The solids are said to be in a fluidized state when they are suspended in the continuous phase.Hydrodynamic properties such as gas hold-up, liquid hold-up and bed porosity have been studied. These properties depend upon certain independent variables such as gas flow rates, liquid flow rate, particle size, static bed heights, gas density, liquid density, solid density, liquid surface tension, liquid viscosity, gas viscosity and particle shape. During the course of this experimental investigation only four of these parameters have been varied, viz, gas flow rates, liquid flow rates, static bed height and particle size.The result of these experimental investigations is discussed and correlations have also been developed for the hydrodynamics properties studied.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1988 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :Martin R Dis Li Publisher :Sudwestdeutscher Verlag Fur Hochschulschriften AG ISBN 13 :9783838133218 Total Pages :372 pages Book Rating :4.1/5 (332 download)
Book Synopsis Bubbling Fluidized Bed Hydrodynamics by : Martin R Dis Li
Download or read book Bubbling Fluidized Bed Hydrodynamics written by Martin R Dis Li and published by Sudwestdeutscher Verlag Fur Hochschulschriften AG. This book was released on 2012-05 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rising gas bubbles in bubbling fluidized beds are important for all hydrodynamics related phenomena, e.g. mass transfer, gas bypassing, heat transfer, gas-solids mixing, etc. However, still many interactions of bubbles with specific operation conditions in fluidized beds are unknown. In this work, fluidized beds with vertical heat exchangers are investigated. Vertical heat exchangers are in this case used to remove the heat of reaction from the exothermal methanation reaction for the production of synthetic natural gas (SNG) from wood. Several vertical tube bank configurations varying in their diameter, tube-to-tube spacing, and arrangement (square vs. triangular) have been immersed into a lab-scale fluidized bed. By means of optical probing and pressure fluctuation measurements, their influence on the rising gas bubbles has been evaluated by means of statistical tools. Findings from these experiments are furthermore used to develop a modified approach to scale up fluidized beds with vertical internals.
Book Synopsis Meubles et objets d'art de bel ameublement... by :
Download or read book Meubles et objets d'art de bel ameublement... written by and published by . This book was released on 1978 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Hydrodynamic Study of Three Phase Semi Fluidized Bed with Irregular and Homogeneous Binary Mixtures by :
Download or read book Hydrodynamic Study of Three Phase Semi Fluidized Bed with Irregular and Homogeneous Binary Mixtures written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluidization refers to a process by which a fluid like state is imparted to granular solid particles by the passing of a fluid upwards through the bed of particles. A semi fluidized bed is characterized by a fluidized bed and a packed bed in a series within a single contacting vessel. Gas-liquid-solid semi fluidization is defined as an operation in which a bed of solid particles is suspended in gas and/or liquid upward flowing media due to the net gravitational force on the particles and the motion of the particles is restricted by a top restraint. Such an operation generates intimate contact between the gas, liquid and solid particles in these systems and provides substantial advantages for applications in physical, Chemical and biochemical processing involving gas, liquid and solid phases. The experiments were conducted using liquid as the continuous phase and gas as the discontinuous phase. In this work air, water and dolomite (2.31mm, and 1.7mm) are used as the gas, liquid and solid phases respectively. The experiments were carried out in a 100 mm ID of 2m height vertical Plexiglas column. Knowledge of minimum liquid semi fluidization velocity is essential for the successful operation of gas-liquid-solid semi fluidized beds. Bed pressure measurements have been made to predict the values of the minimum liquid semi fluidization velocity. In the present work, hydrodynamic characteristics viz., the pressure drop, bed expansion of a co-current gas-liquid-solid semi fluidized bed has been studied. These have done in order to develop a good understanding of each of the flow regime in gas-liquid and liquid-solid semi fluidization. The effect of static bed height, particle size, liquid velocity and gas velocity on hydrodynamics parameters like minimum semi fluidization velocity, pressure drop, expansion ratio have been investigated. Experimental study based on statistical design has been made to investigate the expansion ratio of semi fluidized bed. The experimental val.
