Effect of solid bed height on pressure drop in stationary liquid fluidization

2018 ◽  
Vol 8 (1) ◽  
pp. 6
Author(s):  
S. Kumar ◽  
A. Arora ◽  
H. Chandra
Keyword(s):  
Pressure Drop ◽  
Bed Height ◽  
Stationary Liquid ◽  
Liquid Fluidization

The Pressure Drop at Critical Fluidization of Large Particles in Vibrated Fluidization Bed

2012 ◽  
Vol 550-553 ◽  
pp. 2763-2766
Author(s):  
Xue Jun Zhu ◽  
Jun Deng
Keyword(s):  
Pressure Drop ◽  
Fluidized Bed ◽  
Large Particle ◽  
Particle Diameter ◽  
Future Design ◽  
Vibration Strength ◽  
Bed Height ◽  
Large Particles ◽  
Vibrated Fluidized Bed ◽  
Critical Fluidization

The pressure drop at critical fluidization for two-dimensional vibrated fluidized bed(240 mm×80 mm) was studied, with large particle glass beads of average diameters dp of 1.8mm, 2.5mm and 3.2mm.The effect of the vibration strength, the static bed height and the particle diameter on the pressure drop was analyzed. The results of the study show that the pressure drop decreases with the increase of the vibration strength. It plays an even more prominent part with decreases of the static bed height and the particle diameter. The empirical correlation equations to predict the pressure drop was established, and the results of the prediction was compared with the experimental data, the error is in range of ±10%. The results can provide references for future design and research on the vibrated fluidized bed.

scholarly journals Mathematical Model of Three Dimensional Spouted Bed Using Distinct Element Method

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
S. Laorratanasak ◽  
Thongchai Rohitatisha Srinophakun ◽  
Parichat Mongkolsaowanit
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Continuous Flow ◽  
Distinct Element ◽  
Operating Parameter ◽  
Spouted Bed ◽  
Time Step ◽  
Simple Method ◽  
Bed Height ◽  
Element Method

Spouted bed was simulated by a combining of Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) technique. In the simulation, DEM based on the Newton’s second law of motion was used to solve the particle motion and the fluid motion were obtained by CFD with the SIMPLE method and Upwind scheme. Programming was developed in Standard-C language and MATLABTM was used to visualize the results. The size of particles focused on this simulation is 2.5 mm in diameter (the density = 2,500 kg/m3, stiffness = 800 Nm -1). The time step used to maintain the stability of the simulation was 6.5 10-5 sec.In this simulation, three levels of the static bed height were studied: 45, 58, and 70 mm. The operating parameter effects (the static bed height on the pressure drop across the bed and the minimum spouting velocity) were investigated. The pressure drop across the bed and the minimum spouting velocity increased corresponding to the level increment. In the study of the pulsed and multi-pulsed frequency, it was found that the higher number of frequency introduced the higher heat transfer to the particles. Moreover, the effect of each type of flow on the average particles temperature was studied. The continuous flow gave the highest average particles temperature. Even though, the single pulsed flow and the multiple pulsed flows gave the lower heat transfer than continuous flow, the multiple flows produced a very good distribution in the heat transfer and also can reduce the dead zone problem of the spouted bed.

On the Modeling of Gas-Solid Fluidization: Which Physics Are Most Important to Capture?

2010 ◽  
Author(s):  
Francine Battaglia ◽  
Jonas A. England ◽  
Santhip Kanholy ◽  
Mirka Deza
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Packing Fraction ◽  
Walnut Shell ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Bed Height ◽  
Minimum Fluidization ◽  
Two Parameters ◽  
Bed Material

Recent studies to predict biomass fluidization hydrodynamics motivated a new study to reassess how to model gas-solid characteristics that capture the same physics as that measured in experiments. An Eulerian-Eulerian multifluid model was used to simulate and analyze gas-solid hydrodynamic behavior of the fluidized beds. The relations for the pressure drop measured at fluidization were used to correct for the bed mass by either adjusting the initial solids packing fraction or initial bed height, two parameters that must be specified in a CFD model. Simulations using sand as the bed medium were compared with experiments and it was found that adjusting the bulk density, or in other words, the initial solids volume packing, correctly predicted the pressure drop measured experimentally, but significantly under-predicted the minimum fluidization velocity. By adjusting the initial bed height to correct for the mass, both the pressure drop and minimum fluidization velocity were successfully predicted. Ground walnut shell and ground corncob were used as biomass media and simulations were performed for two reactor bed diameters by simply adjusting the initial bed height to match the measured pressure drop. All of the simulations correctly predicted the pressure drop curves of the experimental data. Further examination of the simulations and experimental data for walnut shell confirmed that adjusting the bed height was the best approach to model fluidization without artificially altering the physics and retaining the known characteristics of the bed material.

A Study on Fluidized Bed-Type Particulate Filter for Diesel Engines

2007 ◽  
Vol 129 (4) ◽  
pp. 1072-1078 ◽  
Author(s):  
Sung-Sub Kee ◽  
Ali Mohammadi ◽  
Takuji Ishiyama ◽  
Takaaki Kakuta
Keyword(s):  
Particle Size ◽  
Diesel Engine ◽  
Pressure Drop ◽  
Fluidized Bed ◽  
Particle Diameter ◽  
Filtration Efficiency ◽  
Particulate Filter ◽  
Design Parameters ◽  
Gas Velocity ◽  
Bed Height

A fluidized bed-type diesel particulate filter (DPF) was applied to filter particulate matter (PM) in diesel engine exhaust gas. The effects of the fluidized bed design parameters, such as gas velocity, bed particle size, and height, on PM and smoke filtration efficiencies, and pressure drop were experimentally investigated using a single-cylinder direct injection (DI) diesel engine. High PM filtration efficiency and low pressure drop were achieved with the DPF, especially at a lower gas velocity. The PM filtration efficiency was higher with a smaller bed particle size at the lower gas velocity; however, it drastically decreased with an increase in gas velocity due to excessive fluidization of the bed particles. Increase in bed height led to higher PM filtration efficiency while causing an increase in pressure drop. The theoretical work was also conducted for further investigation of the effects of the above-mentioned parameters on PM filtration. These results indicated that diffusion filtration was the dominant mechanism for PM filtration under the conditions of this study and that the decrease in PM filtration efficiency at high gas velocity was caused by a deterioration in the diffusion filtration. The bed particle diameter and the bed height should be optimized in order to obtain a high filtration efficiency without increasing the DPF size.

scholarly journals Modelling of a Heated Gas-solid Fluidised Bed using Eulerian Based Models

R&D Journal ◽  
2021 ◽  
Author(s):  
A. Potgieter ◽  
M. Bhamjee ◽  
S. Kruger
Keyword(s):  
Pressure Drop ◽  
Fixed Bed ◽  
Fluidised Bed ◽  
Bubble Interactions ◽  
Bed Height ◽  
Chamber Height ◽  
Model Predictions ◽  
Computational Fluid Dynamics Cfd ◽  
Fluidised Beds ◽  
Bed Expansion

ABSTRACT An Eulerian-Eulerian granular model was used to simulate the flow and heat transfer through a heatedgassolid fluidised bed. The primary objective of the study was to determine whether the Eulerian-Eulerian granular model adequately predicts the chamber pressure drop, temperature, and bed expansion through the bed. The model predictions were assessed and validated for various flow-regimes, namely the fixed-bed, smooth, bubbling fluidisation, and the maximum fluidisation regimes. This was done on an experimental scale heated gas-solid fluidised bed. However, the results are generalisable for heated gas-solid fluidised beds when the flow is laminar. Numerical models were created using Computational Fluid Dynamics (CFD). The CFD-model predictions were investigated, analysed, and compared to experimental results. Basic experiments were carried out to obtain varying hydrodynamic characteristics. The results showed a slight overprediction of pressure drop and bed expansion, however, the results were still in close agreement with the experiment. In contrast, underprediction of chamber temperatures were obtained. Based on the results of this study, it is recommended that the Eulerian model be used to predict dynamic flow behaviour. Before minimum fluidisation, when in a fixed bed regime, pressure drop in the chamber increases with no increase in bed height. No visible bubbles were present in the fixed bed regime. When fluidisation has been reached, the bed height rises whereas the pressure drop tends to a constant value. Bubble size increases with chamber height and increased superficial velocities. Bubble speed increased with increased chamber height. With increased superficial velocity, the chamber temperatures increase to a maximum temperature of326.65 K with an initial heating element temperature of373.15 K. However, when excessive heat is present in the gas-solid fluidised bed, other methods that sufficiently incorporate particle-particle interactions and bubble-bubble interactions, are recommended. An investigation should be lent to bubble-bubble interactions in the fluidised beds with relation to heat transfer. Additional keywords: Heated fluidised bed, computational fluid dynamics, CFD, Eulerian, granular, fluidisation, gas-solid

scholarly journals Absorption in a three-phase fluidized bed I: Hydrodynamic investigations

2003 ◽  
Vol 57 (7-8) ◽  
pp. 326-329 ◽  
Author(s):  
Srdjan Pejanovic
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Gas Flow ◽  
Minimum Fluidization Velocity ◽  
Bed Height ◽  
Three Phase ◽  
Height Increase ◽  
Improve Mass Transfer

The hydrodynamic properties of a three phase fluidized bed with low density inert spherical packing, fluidized by the interaction of a gas flowing upwards and a liquid flowing downwards through the column, were investigated. It was found that the pressure drop, liquid hold up and dynamic bed height increase with both increasing liquid and gas flow rate. While the dynamic bed height and minimum fluidization velocity remain unchanged, both the pressure drop and liquid hold up increase with increasing density of the packing. Therefore, an increase in packing density causes more intensive mass transfer between the fluid phases than packed columns. It was shown that increase of the liquid flow rate causes an increase of both the effective liquid and gas velocity through the fluidized bed, which may also improve mass transfer.

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