Bed height and material density effects on fluidized bed hydrodynamics

Escudero, David R.

doi:10.31274/etd-180810-1789

Cited by 16 publications

(39 citation statements)

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“…They showed that for 3D beds, the minimum fluidization velocity remained constant no matter the bed height used in the experiments. Similar results showing independence between minimum fluidization velocity and bed height were concluded by Escudero and Heindel [8] using different Geldart type B particles (glass beads, ground walnut shell and ground corncob) in the size range of 500-600 J.Lm.…”

Section: Introductionsupporting

confidence: 71%

Acoustic Field Effects on Minimum Fluidization Velocity in a 3D Fluidized Bed

Escudero

Heindel

2012

Volume 2: Fora

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Fluidized beds are used in a variety of process industries because they provide uniform temperature distributions, low pressure drops, and high heat/mass rates. Minimum fluidization velocity is an important factor in understanding the hydrodynamic behavior of fluidized beds, and this characteristic may be modified through high frequency (sound) vibrations. The effects caused by sound wave frequency on the minimum fluidization velocity in a 3D fluidized bed are investigated in this study. Experiments are carried out in a 10.2 cm ID cold flow fluidized bed filled with glass beads with material density of 2600 kg/m 3 , and particles sizes ranging between 212-600 μm. In this study, four different bed height-to-diameter ratios are examined: H/D = 0.5, 1, 1.5, and 2. Moreover, the sound frequency of the loudspeaker used as the acoustic source ranges between 50-200 Hz, with a sound pressure level fixed at 110 dB. Results show that the minimum fluidization velocity is influenced by the frequency change. As the frequency increases, the minimum fluidization velocity decreases until a specific frequency is reached, beyond which the minimum fluidization velocity increases. Thus, acoustic fields provide an improvement in the ease of fluidization of these particles. ABSTRACT Fluidized beds are used in a variety of process industries because they provide uniform temperature distributions, low pressure drops, and high heat/mass rates. Minimum fluidization velocity is an important factor in understanding the hydrodynamic behavior of fluidized beds, and this characteristic may be modified through high frequency (sound) vibrations. The effects caused by sound wave frequency on the minimum fluidization velocity in a 3D fluidized bed are investigated in this study. Experiments are carried out in a 10.2 em ID cold flow fluidized bed filled with glass beads with material density of 2600 kg/m 3 , and particles sizes ranging between 212-600 J.lm. In this study, four different bed height-todiameter ratios are examined: HID = 0.5, 1, 1.5, and 2. Moreover, the sound frequency of the loudspeaker used as the acoustic source ranges between 50-200 Hz, with a sound pressure level fixed at 110 dB. Results show that the minimum fluidization velocity is influenced by the frequency change. As the frequency increases, the minimum fluidization velocity decreases until a specific frequency is reached, beyond which the minimum fluidization velocity increases. Thus, acoustic fields provide an improvement in the ease of fluidization of these particles.

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Section: Introductionsupporting

confidence: 71%

Acoustic Field Effects on Minimum Fluidization Velocity in a 3D Fluidized Bed

Escudero

Heindel

2012

Volume 2: Fora

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“…Both the original data and averaged data are recorded for further analysis. More details about the fluidized bed system are available in Escudero and Heindel …”

Section: Methodsmentioning

confidence: 99%

Using stereo XPTV to determine cylindrical particle distribution and velocity in a binary fluidized bed

2018

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Nonspherical particles are commonly found when processing biomass or municipal solid waste. In this study, cylindrical particles are used as generic nonspherical particles and are co‐fluidized with small spherical particles. X‐ray particle tracking velocimetry is used to track the three‐dimensional particle position and velocity of a single tagged cylindrical particle over a long time period in the binary fluidized bed. The effects of superficial gas velocity (u f), cylindrical particle mass fraction (α), particle sphericity (Φ), and bed material size on the cylindrical tracer particle location and velocity are investigated. Overall, the cylindrical particles are found in the near‐wall region more often than in the bed center region. Increasing the superficial gas velocity u f provide a slight improvement in the uniformity of the vertical and horizontal distributions. Increasing the cylindrical particle mass fraction α causes the bed mixing conditions to transition from complete mixing into partial mixing. © 2018 American Institute of Chemical Engineers AIChE J, 65: 520–535, 2019

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“…To ensure the same response for each condition from the detector system, each CT is taken with the same X-ray source power settings for the respective conditions. The local time-average gas holdup is then determined from the two reference CT images and the flow CT image [10]:…”

Section: -D Imagementioning

confidence: 99%

“…Escudero and Heindel [ 10,12] studied the effects of bed height, superficial gas velocity, and bed material on the local time-average gas holdup of a 10.2 em fluidized bed, using Xray computed tomography. Using different materials (glass beads, ground corncob, and ground walnut shell), superficial gas velocities (U 8 ), and height-to-diameter ratio (H/D), they determined the variations on the fluidization hydrodynamics of the bed.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, having multiple scans fi·om different projections give a high spatial resolution to this technique, a characteristic that can be used to measure the local time-average gas holdup in a very efficient way. [10] Moreover, XCT data analysis allows for the calculation of time-average local gas holdup or solid holdup. Grassier and Wirth [11] used XCT to determine the solids concentration in a 0.19 m diameter circulating fluidized bed with 50-70 f!m glass beads as the bed material.…”

Section: Introductionmentioning

confidence: 99%

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Characterizing Acoustic Fluidized Bed Hydrodynamics Using X-Ray Computed Tomography

Escudero

Heindel

2013

Volume 2, Fora: Cavitation and Multiphase Flow; Fluid Measurements and Instrumentation; Microfluidics; Multiphase Flows: Work I

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Fluidized bed reactors are important assets of many industrial applications because they provide uniform temperature distributions, low pressure drops, and high heat/mass rates. Characterizing the hydrodynamics of a fluidized bed is important to better understand the behavior of these multiphase flow systems. The hydrodynamic behavior in a cold flow 3D fluidized bed, with and without acoustic intervention, using X-ray computed tomography is investigated in this study. Experiments are carried out in a 10.2 cm ID fluidized bed filled with glass beads, with material density of 2600 kg/m 3 and particle size ranges between 212-600 μm. In this study, three different bed height-to-diameter ratios are examined: H/D = 0.5, 1 and 1.5. Moreover, the sound frequency of the loudspeaker used as the acoustic source is fixed at 150 Hz with a sound pressure level of 120 dB. Local time-average gas holdup results show that the fluidized bed under the presence of an acoustic field provides a more uniform fluidization, the bed exhibits less channeling, and the jetting phenomena produced by the distributor plate is less prominent when compared to no acoustic field. Thus, acoustic intervention affects the hydrodynamic behavior of the fluidized bed. KeywordsAcoustic fluidized bed, hydrodynamics, x-ray computed tomography ABSTRACT Fluidized bed reactors are important assets of many industrial applications because they provide uniform temperature distributions, low pressure drops, and high heat/mass rates. Characterizing the hydrodynamics of a fluidized bed is important to better understand the behavior of these multiphase flow systems. The hydrodynamic behavior in a cold flow 3D fluidized bed, with and without acoustic intervention, using X-ray computed tomography is investigated in this study. Experiments are carried out in a 10.2 em ID fluidized bed filled with glass beads, with material density of 2600 kg/m 3 and particle size ranges between 212-600 ~un. In this study, three different bed height-to-diameter ratios are examined: HID = 0.5, 1 and 1.5. Moreover, the sound frequency of the loudspeaker used as the acoustic source is fixed at 150Hz with a sound pressure level of 120 dB. Local time-average gas holdup results show that the fluidized bed under the presence of an acoustic field provides a more uniform fluidization, the bed exhibits less channeling, and the jetting phenomena produced by the distributor plate is less prominent when compared to no acoustic field. Thus, acoustic intervention affects the hydrodynamic behavior of the fluidized bed.

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Bed height and material density effects on fluidized bed hydrodynamics

Cited by 16 publications

References 0 publications

Acoustic Field Effects on Minimum Fluidization Velocity in a 3D Fluidized Bed

Acoustic Field Effects on Minimum Fluidization Velocity in a 3D Fluidized Bed

Using stereo XPTV to determine cylindrical particle distribution and velocity in a binary fluidized bed

Characterizing Acoustic Fluidized Bed Hydrodynamics Using X-Ray Computed Tomography

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