On the Incipient Fluidized State of Solid Particles

1993 ◽  
Vol 58 (6) ◽  
pp. 1213-1241 ◽  
Author(s):  
Miloslav Hartman ◽  
Robert W. Coughlin
Keyword(s):  
Fixed Bed ◽  
Packed Bed ◽  
Solid Particles ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Minimum Fluidization ◽  
Turbulent Flow Regime ◽  
Temperature And Pressure ◽  
Particle Size And Shape ◽  
Comprehensive Study

A comprehensive study has been reported on all aspects of the transition of packed bed to the state of incipient fluidization (point of minimum fluidization, onset of fluidization): particle size and shape, size distribution in a batch of particles, fixed bed voidage, pressure drop through a packed bed and oneset of fluidization. A number of predictive equations have been compared that were proposed to estimate the minimum fluidization velocity. All the equations tested do not have any flow limitations and are applicable to laminar, transitional as well as to turbulent flow regime. While some equations have some foundation in theory, the other are more or less generalized correlations of experimental data amassed by different authors under various conditions. The influence of temperature and pressure on the minimum fluidization velocity has been explored with respect to the important applications such as combustion and gasification. Problems have also been discussed with transition from fixed to fluidized bed of binary and polydisperse systems.

Minimum Fluidization Velocity of Binary Particles with Different Geldart Classification

2012 ◽  
Vol 482-484 ◽  
pp. 655-662
Author(s):  
Jun Tang ◽  
Xiao Na Chen ◽  
Chun Xi Lu ◽  
Yong Min Zhang
Keyword(s):  
Mass Fraction ◽  
Particle Systems ◽  
Solid Particles ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Minimum Fluidization ◽  
Group A ◽  
Solid Phases ◽  
The Difference ◽  
Equal Density

The minimum fluidization behavior of four different binary particle systems with different Geldart classification is experimentally investigated by carrying out slow defluidization of an experimental cold device of I.D. 300 mm and height 3 m. The solid particles are four kinds of quartz sand particles with equal density, corresponding to Group A, B, C and D particles of Geldart classification, respectively. The fluidization processes can be divided into packing state, partial fluidization state and complete fluidization state. The difference in physical properties and mass fraction of the two constituent solid phases is found to strongly influence the fluidization behavior and the minimum fluidization velocity during the slow defluidization process. For binary particle systems, the minimum fluidization velocity decreases with increasing mass fraction of the component whose fluidization quality is better. Finally, the models of Noda et al. (1986), Cheung et al. (1974) and Chiba et al. (1979) are used to predict the minimum fluidization velocity of above binary particle systems.

Correlation for Prediction of Minimum Fluidization Velocity and Riser Liquid Holdup in Three-Phase External Loop Air Lift Fluidized Bed Reactor

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Sivakumar Venkatachalam ◽  
Kannan Kandasamy ◽  
Senthilkumar Kandasamy
Keyword(s):  
Fluidized Bed ◽  
Fluidized Bed Reactor ◽  
Solid Particles ◽  
Liquid Holdup ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
External Loop ◽  
Minimum Fluidization ◽  
Newtonian Liquids ◽  
Air Lift

The effect of superficial gas and liquid velocities and properties of solids on the minimum fluidization velocity and riser liquid holdup of a three-phase external loop air lift fluidized bed reactor was characterized using Newtonian and non-Newtonian systems. Water, 65% and 85% of glycerol and n-Butanol were used as Newtonian liquids and different concentrations of carboxymethyl cellulose (i.e. 0.2%, 0.5% and 1% CMC) were used as non-Newtonian liquids. Spherical glass beads, bearl saddles and rasching rings of different sizes were used as solid phases. The phase flow rates and properties of solid particles had significant effects on the hydrodynamic characteristics of the external loop air lift fluidized bed reactor, such as minimum fluidization velocity and riser liquid holdup. Unified correlations have been developed to estimate the minimum fluidization velocity and riser liquid holdup as a function of superficial phase velocities, properties of solid particles and physical properties of both Newtonian and non-Newtonian liquid systems. The predicting ability of the correlations were tested with the experimental data and found to be a good fit with an absolute average relative deviation (AARD) of ± 6.5 % and ± 7.8 % for minimum fluidization velocity and riser liquid holdup, respectively.

scholarly journals Significance of the particle physical properties and the Geldart group in the use of correlations for the prediction of minimum fluidization velocity of biomass–sand binary mixtures

2021 ◽  
Author(s):  
Louis Edwards Cáceres-Martínez ◽  
Diana Carolina Guío-Pérez ◽  
Sonia Lucía Rincón-Prat
Keyword(s):  
Physical Properties ◽  
Binary Mixtures ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Minimum Fluidization ◽  
Mass Fractions ◽  
Char Particle ◽  
Geldart Groups ◽  
Biomass Particles

AbstractThe present study explores the relevance of the physical properties of biomass particles on the determination of the minimum fluidization velocity (Umf) of binary mixtures. Fluidization experiments were performed in a cold flow unit with diverse biomasses mixed with sand in different mass fractions. Gas velocity and pressure drop across the bed were used to determine Umf. Different correlations reported in the literature were evaluated on their ability to accurately predict Umf of the mixtures. Results showed satisfactory predictions when appropriately identifying correlations according to the corresponding Geldart groups for the biomass particles. This perspective opens new possibilities toward the generalization of correlation factors and helps in improving the accuracy of the prediction for highly heterogeneous mixtures. The methodology also allows the analysis of mixtures for which the experimental approach is difficult, such as those including char particle, with the only requirement of carefully measuring the physical properties of the particles.

scholarly journals Prediction of minimum fluidization velocity in pulsed gas–solid fluidized bed

2020 ◽  
pp. 127965
Author(s):  
Yanjiao Li ◽  
Chenyang Zhou ◽  
Guannan Lv ◽  
Yongxin Ren ◽  
Yuemin Zhao ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Minimum Fluidization
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