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B C Meikap - One of the best experts on this subject based on the ideXlab platform.
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characteristics of minimum Fluidization Velocity for magnetite powder used in an air dense medium fluidized bed for coal beneficiation
Particle & Particle Systems Characterization, 2012Co-Authors: S Mohanta, Anil Babu Daram, Sudipto Chakraborty, B C MeikapAbstract:Accurate determination of minimum Fluidization Velocity of medium particle is essential for proper designing and operation of an Air Dense Medium Fluidized Bed Separator for coal beneficiation. Significantly different values of minimum Fluidization Velocity have been obtained from different available correlations. So, it is necessary to develop a suitable correlation for this specific purpose. In this study, the minimum Fluidization velocities of different size magnetite powders are investigated in a 15 cm diameter fluidized bed. Three correlations are derived from the fundamental principles for the theoretical prediction of these minimum Fluidization velocities. The adequacy and reliability of each of these correlations is tested by adopting a statistical analysis approach and the most suitable correlation is selected. The predictive capability of this selected correlation is verified by using the data available in the literature. The results show that this new correlation is in very well agreement with these experimental data and shown to be applicable for practical purpose. Moreover, this study reveals that the correlation developed from the basic particle properties and bed characteristics can predict more accurate results.
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characterization of hydrodynamic properties of a gas liquid solid three phase fluidized bed with regular shape spherical glass bead particles
Chemical Engineering Journal, 2008Co-Authors: Hara Mohan Jena, G K Roy, B K Sahoo, B C MeikapAbstract:The hydrodynamic characteristics, viz., the pressure drop, bed expansion and phase hold-up of a cocurrent gas–liquid–solid three-phase fluidized bed has been studied using liquid as the continuous phase and gas as the discontinuous phase. These have been done in order to develop a good understanding of each flow regime in gas–liquid and liquid–solid Fluidization. Air, water and glass beads (2.18, 3.05 and 4.05 mm, respectively) are used as the gas, liquid and solid phases, respectively. The experiments were carried out in a 100 mm ID, 2 m-height vertical Plexiglas column. The column consists of three sections, viz., the gas–liquid disengagement section, test section and gas–liquid distributor section. Bed pressure measurements have been made to predict the minimum liquid Fluidization Velocity. By keeping gas Velocity at a fixed value, the liquid Velocity was varied and the effect on phase hold-up, minimum liquid Fluidization Velocity, pressure drop and the expansion ratio was studied for different particle size and static bed height. Experimental study based on statistical design has been made to investigate the expansion ratio of fluidized bed and a correlation has been developed for gas hold-up. It is evident from the correlation that gas hold-up is strongly function of modified gas Reynolds number and independent of liquid Reynolds number. The experimental values have been compared with those predicted by the
David Pallares - One of the best experts on this subject based on the ideXlab platform.
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a novel experimental method for determining lateral mixing of solids in fluidized beds quantification of the splash zone contribution
Powder Technology, 2020Co-Authors: Guillermo Martinez Castilla, Louise Lundberg, Filip Johnsson, Anton Larsson, David PallaresAbstract:An experimental method to investigate the lateral mixing of bulk solids in bubbling fluidized beds is presented.The method utilizes finite volume analysis of the measured temperature field over the bed surface, from which the solids dispersion coefficient is determined. The temperature field is measured with a thermographic camera,which in this work is applied to a fluid-dynamically down-scaled fluidized bed that resembles the conditions relevant for hot large-scale operation.The method is applied to investigate the effect of key parameters for the solids mixing process; Fluidization Velocity, particle size and pressure drop over the air distributor plate. The results showed up-scaled dispersion coefficients in the order of 10−3m2/s for the conditions investigated. The lateral mixing of solids decreased with increasing particle size and increased with increases in the Fluidization Velocity and pressure drop over the air distributor. The method was also used to quantify the contribution of the splash zone to the total lateral solids mixing. When lateral solids mixing in the splash zone was blocked with a vertical baffle the lateral solids dispersion was reduced by some 90%.
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lateral fuel dispersion in a large scale bubbling fluidized bed
Chemical Engineering Science, 2012Co-Authors: David Pallares, Johanna Olsson, Filip JohnssonAbstract:The lateral fuel dispersion in a large-scale (1.44 m(2) in cross section) bubbling fluidized bed operated under ambient conditions has been investigated by means of particle tracking with video recording and subsequent digital image analysis. Wood chips and bark pellets were used as tracer particles. Characterization of the fuel mixing pattern was made by single tracer particle tracking while tracking of batches of tracer particles was applied to quantify the fuel mixing through lateral dispersion coefficients. The experimental technique shows good repeatability and dispersion coefficients are found to be in the order of 10(-3) m(2)/s. The lateral transport of the wood chips is observed to occur mainly while these are submerged in the dense bed. Increased Fluidization Velocity accentuates this pattern, i.e. the share of time spent in the dense bed increases. Only for the wood chips the Fluidization Velocity was found to have an influence on the lateral dispersion coefficient, which is due to that these are of larger size and lower density than the bark particles. Diffusion-type modeling of the horizontal fuel dispersion is discussed, concluding that such an approach is not suitable in cases with low lateral fuel mixing rate or with a characteristic mixing length in the same order as the lateral length scale of the bed. As alternative, this paper proposes a macroscopic modeling approach for the lateral fuel mixing, which includes physical parameters relating to the local mixing mechanisms, operational conditions and fuel particle properties. The proposed model is shown to give an adequate macroscopic description of the lateral fuel mixing.
Chenlong Duan - One of the best experts on this subject based on the ideXlab platform.
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minimum Fluidization Velocity growth due to bed inventory increase in an air dense medium fluidized bed
Chemical Engineering Journal, 2019Co-Authors: Jesse Zhu, Yuemin Zhao, Shahzad Barghi, Zhenfu Luo, Chenlong DuanAbstract:Abstract Minimum Fluidization Velocity is one of the most important Fluidization characteristics when applying an Air Dense Medium Fluidized Bed to dry coal beneficiation. Measurements were carried out for magnetite particles (150–300 μm) and the binary mixtures of magnetite mixed with sand/gangue/coal particles (300–425 μm) to determine the influence of bed inventory on the characteristics at incipient Fluidization state. The experimental results demonstrate that the minimum Fluidization velocities of both single and binary mixtures of solid particles increase with increasing bed mass, which has not properly accomplished by the existing equations. The correlation proposed by Wen and Yu has been modified to predict the minimum Fluidization Velocity as a function of bed inventory. It only requires the knowledge of Archimedes number and the pressure drop of fluidized bed. This correlation is in reasonable agreement with almost all available data in the literature and the present work.
Jesse Zhu - One of the best experts on this subject based on the ideXlab platform.
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minimum Fluidization Velocity growth due to bed inventory increase in an air dense medium fluidized bed
Chemical Engineering Journal, 2019Co-Authors: Jesse Zhu, Yuemin Zhao, Shahzad Barghi, Zhenfu Luo, Chenlong DuanAbstract:Abstract Minimum Fluidization Velocity is one of the most important Fluidization characteristics when applying an Air Dense Medium Fluidized Bed to dry coal beneficiation. Measurements were carried out for magnetite particles (150–300 μm) and the binary mixtures of magnetite mixed with sand/gangue/coal particles (300–425 μm) to determine the influence of bed inventory on the characteristics at incipient Fluidization state. The experimental results demonstrate that the minimum Fluidization velocities of both single and binary mixtures of solid particles increase with increasing bed mass, which has not properly accomplished by the existing equations. The correlation proposed by Wen and Yu has been modified to predict the minimum Fluidization Velocity as a function of bed inventory. It only requires the knowledge of Archimedes number and the pressure drop of fluidized bed. This correlation is in reasonable agreement with almost all available data in the literature and the present work.
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effects of acoustic vibration on nano and sub micron powders Fluidization
Powder Technology, 2011Co-Authors: S Kaliyaperumal, Shahzad Barghi, Jesse Zhu, Lauren Briens, Sohrab RohaniAbstract:Fluidization of nano and sub-micron powders with and without acoustic vibration was investigated. The effects of sound pressure level and frequency were studied. Loudspeakers located under the distributor plate were used as the sound source to disintegrate larger agglomerates concentrated at the bottom of the bed. Nanoparticles showed fluid-like behavior similar to Geldart's A group and application of sound vibration improved their Fluidization quality. Submicron particles were hard to fluidize and their Fluidization quality was partially improved by sound excitation. Bed compaction, caused by rearranging of the agglomerates, was observed for submicron particles at low gas velocities while the bed was fixed. Nanoparticles did not experience any bed compaction. Sound vibration led to a decrease in minimum Fluidization Velocity and an increase in bed pressure drop and bed expansion for both types of particles. The Fluidization quality of both particles increased at low frequencies, while the reverse was observed at higher frequencies. Fluidization of these particles was improved by increasing sound pressure level. There was a critical sound pressure level of 110 dB, below which the effect of sound vibration was insignificant. A novel technique was employed to find the apparent minimum Fluidization Velocity from pressure drop signals.
Filip Johnsson - One of the best experts on this subject based on the ideXlab platform.
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a novel experimental method for determining lateral mixing of solids in fluidized beds quantification of the splash zone contribution
Powder Technology, 2020Co-Authors: Guillermo Martinez Castilla, Louise Lundberg, Filip Johnsson, Anton Larsson, David PallaresAbstract:An experimental method to investigate the lateral mixing of bulk solids in bubbling fluidized beds is presented.The method utilizes finite volume analysis of the measured temperature field over the bed surface, from which the solids dispersion coefficient is determined. The temperature field is measured with a thermographic camera,which in this work is applied to a fluid-dynamically down-scaled fluidized bed that resembles the conditions relevant for hot large-scale operation.The method is applied to investigate the effect of key parameters for the solids mixing process; Fluidization Velocity, particle size and pressure drop over the air distributor plate. The results showed up-scaled dispersion coefficients in the order of 10−3m2/s for the conditions investigated. The lateral mixing of solids decreased with increasing particle size and increased with increases in the Fluidization Velocity and pressure drop over the air distributor. The method was also used to quantify the contribution of the splash zone to the total lateral solids mixing. When lateral solids mixing in the splash zone was blocked with a vertical baffle the lateral solids dispersion was reduced by some 90%.
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lateral fuel dispersion in a large scale bubbling fluidized bed
Chemical Engineering Science, 2012Co-Authors: David Pallares, Johanna Olsson, Filip JohnssonAbstract:The lateral fuel dispersion in a large-scale (1.44 m(2) in cross section) bubbling fluidized bed operated under ambient conditions has been investigated by means of particle tracking with video recording and subsequent digital image analysis. Wood chips and bark pellets were used as tracer particles. Characterization of the fuel mixing pattern was made by single tracer particle tracking while tracking of batches of tracer particles was applied to quantify the fuel mixing through lateral dispersion coefficients. The experimental technique shows good repeatability and dispersion coefficients are found to be in the order of 10(-3) m(2)/s. The lateral transport of the wood chips is observed to occur mainly while these are submerged in the dense bed. Increased Fluidization Velocity accentuates this pattern, i.e. the share of time spent in the dense bed increases. Only for the wood chips the Fluidization Velocity was found to have an influence on the lateral dispersion coefficient, which is due to that these are of larger size and lower density than the bark particles. Diffusion-type modeling of the horizontal fuel dispersion is discussed, concluding that such an approach is not suitable in cases with low lateral fuel mixing rate or with a characteristic mixing length in the same order as the lateral length scale of the bed. As alternative, this paper proposes a macroscopic modeling approach for the lateral fuel mixing, which includes physical parameters relating to the local mixing mechanisms, operational conditions and fuel particle properties. The proposed model is shown to give an adequate macroscopic description of the lateral fuel mixing.