Determination of onset of bubbling and slugging in a fluidized bed using a dual-plane electrical capacitance tomography system

Agu, Cornelius Emeka; Tokheim, Lars-André; Eikeland, Marianne Sørflaten; Moldestad, Britt Margrethe Emilie

doi:10.1016/j.cej.2017.07.098

Cited by 38 publications

(27 citation statements)

References 22 publications

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“…It was observed that directly after the Umf observation, the bubbling velocity was noticed where many bubbles appeared above the distributor plate, they became larger and moved upwards through the bed. Also the values of Umf and Umb are approximately the same and that agreed with (Agu, et al, 2017) and (Cocco, et al, 2014) ,that the behavior of this kind of material was according to Geldart classification and can be considered of kind B. Also that agreed well with (Jaiswal, et al, 2018) There was a short period of particulate fluidization (Umb -Umf) with a range of (0.01-0.004 m/s) shown in Table 2.…”

Section: Resultssupporting

confidence: 81%

“…8 and 9, it is obvious that there was not a large dependence on static bed height and column diameter also the values were around 1, these values mean the bed has a less capacity to hold gases and a large possibility to form bubbles for a small increase in air velocity above the minimum fluidization velocity .It can be concluded that for materials of Geldart type B, the fluidization index was nearly unity and that agreed well with (Gajbliye, et al, 2013) and (Ram, 2013). For further increase in gas velocity, slug started to form, it was noted visually with the structure of rounded-nosed, that agreed with (Agu, et al, 2017) , for easy fluidized materials, the material used was considered of this type, the slug had that structure and it can be noted visually for narrow (shallow) beds. The experimental and calculated values of Ums are shown in Table 3.…”

Section: Resultssupporting

confidence: 68%

“…(Gajbliye, et al, 2013) ,studied the hydrodynamics and stability of a fluidized bed with respect to minimum bubbling velocity, minimum fluidization velocity and fluidization quality ,they used Geldart group B particles ,they named the fluidization quality for Umb /Umf and it was equal to one for this type. (Agu, et al, 2017) ,had an experimental study on samples of 150-450 ϻm limestone particles and two samples of 100-550 ϻm glass beads, they concluded that the bubbling velocity is determined when the first bubble was observed in the top of the fluidized bed also they mentioned that for a bed of Geldart B type with particles size range 100-1000 ϻm, the bubbles appear as soon as the fluidization is started.…”

Section: Fi =mentioning

confidence: 99%

“…The flow shifts from slug in to turbulent with further rise in gas velocity, the turbulent flow marked with the bubbles and slug absence in the bed and that followed by particles movement and transportation . (Jaiswal, et al, 2018) and (Agu, et al, 2017) mentioned that the transition from a type of flow to another depends on many factors i.e. static bed height, fluidizing gas flow rate, column diameter, particle density, particle size and others.…”

Section: Introductionmentioning

confidence: 99%

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A Study of the Hydrodynamics Behavior of Cylindrical Gas-Solid Fluidized Beds for pharmaceutical material “Paracetamol “

Alwan

2020

jcoeng

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The hydrodynamics behavior of gas - solid fluidized beds is complex and it should be analyzed and understood due to its importance in the design and operating of the units. The effect of column inside diameter and static bed height on the minimum fluidization velocity, minimum bubbling velocity, fluidization index, minimum slugging velocity and slug index have been studied experimentally and theoretically for three cylindrical columns of 0.0762, 0.15 and 0.18 m inside diameters and 0.05, 0.07 and 0.09 m static bed heights .The experimental results showed that the minimum fluidization and bubbling velocities had a direct relation with column diameter and static bed height .The minimum slugging velocity had an inverse relation with static bed height and a direct one with column diameter .There was no agreement between the experimental and calculated values of Umb for Di=0.0762m ,this was a result to the assumption used in the correlation development. The fluidization index values were around 1 in all cases and that proved that the material is of Geldart type B. There was not a significant dependence of fluidization index and slug index on static bed height and column diameter.

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Section: Resultssupporting

confidence: 81%

Section: Resultssupporting

confidence: 68%

Section: Fi =mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Study of the Hydrodynamics Behavior of Cylindrical Gas-Solid Fluidized Beds for pharmaceutical material “Paracetamol “

Alwan

2020

jcoeng

View full text Add to dashboard Cite

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“…Therefore, the Landweber iteration algorithm is used to reconstruct solids distribution and identify the flow regime in gassolids fluidised beds. Table 2 Image reconstruction for gas-solids fluidised beds Authors ECT sensors Image reconstruction algorithm Dyakowski et al (2000) Circular, 8 electrodes Landweber iteration Liu et al (2002Liu et al ( , 2005 Rectangular, 12 electrodes Landweber iteration with optimized iteration step length Marashdeh et al (2006) Circular, 12 electrodes Non-linear Neural network based iteration Wang et al (2008) Rectangular, 12 electrodes Landweber iteration with optimized step length Banaei et al (2015) Circular, 12 electrodes Landweber iteration and Tikhonov iteration Chandrasekera et al (2015) Circular, 12 electrodes Total variation iterative soft thresholding algorithm Zhao et al (2016) Circular, 12 electrodes LBP Agu et al (2017) Circular, 12 electrodes LBP Li et al (2017) Circular, 8 electrodes LBP…”

Section: Ect Image Reconstructionmentioning

confidence: 99%

Application of process tomography in gas–solid fluidised beds in different scales and structures

Wang

Che

et al. 2018

Meas. Sci. Technol.

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Gas-solids fluidised beds are commonly used in particle-related processes, e.g. for coal combustion and gasification in the power industry, and coating and granulation process in the pharmaceutical industry. Because the operation efficiency depends on the gas-solids flow characteristics, it is necessary to investigate the flow behaviour. This paper is about application of process tomography, including electrical capacitance tomography (ECT) and microwave tomography (MWT), in multi-scale gas-solids fluidisation processes in the pharmaceutical and power industries. This is the first time that both ECT and MWT are applied for this purpose with multi-scales and complex structure. To evaluate the sensor design and image reconstruction and to investigate the effects of sensor structure and dimension on the image quality, a normalised sensitivity coefficient is introduced. In the meanwhile, computational fluid dynamic (CFD) analysis based on a computational particle fluid dynamic (CPFD) model and a two-phase fluid model (TFM) is used. Part of the CPFD-TFM simulation results are compared and validated by experimental results from ECT and/or MWT. By both simulation and experiment, the complex flow hydrodynamic behaviour in different scales is analysed. Time-series capacitance data are analysed both in time and frequency domains to reveal the flow characteristics.

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Investigation of fluidized bed behaviour using electrical capacitance tomography

et al. 2020

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The temporal and cross-sectional distributions of particles in a 127 mm diameter fluidized bed have been obtained using a new generation, high-speed Electrical Capacitance Tomography. Two planes of eight electrodes were used and mounted at 160 and 660 mm from the gas distributor which was a 3 mm thick porous plastic plate made (maximum pore size of 50-70 m). 3 mm diameter, nearly-spherical polyethylene granules made up the bed. Experiments at sampling frequencies of 200-2000 cross-sections per second and gas superficial velocities from just below the minimum fluidization to 83% above minimum fluidization velocities were used. The time series of the cross-sectional average void fractions have been examined both directly and in amplitude and frequency space. The last two used Probability Density Functions and Power Spectral Densities. The information generated show that the fluidized bed is operating in the slugging mode, not surprising given the size of the particles. It has been found that an increase of the excess gas velocity above the minimum fluidization velocity resulted in the increase of the mean void fraction, length and velocity of the slug bubbles as well as the bed height, and in a slight decrease of the slug frequency. The results are presented in a level of detail suitable for comparison with later numerical simulation.

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Determination of onset of bubbling and slugging in a fluidized bed using a dual-plane electrical capacitance tomography system

Cited by 38 publications

References 22 publications

A Study of the Hydrodynamics Behavior of Cylindrical Gas-Solid Fluidized Beds for pharmaceutical material “Paracetamol “

A Study of the Hydrodynamics Behavior of Cylindrical Gas-Solid Fluidized Beds for pharmaceutical material “Paracetamol “

Application of process tomography in gas–solid fluidised beds in different scales and structures

Investigation of fluidized bed behaviour using electrical capacitance tomography

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