Influence of vertical internals on a bubbling fluidized bed characterized by X-ray tomography

Maurer, Simon; Wagner, Evert C.; Ommen, J. Ruud van; Schildhauer, Tilman J.; Teske, Sinan L.; Biollaz, Serge M.A.; Wokaun, Alexander; Mudde, Robert F.

doi:10.1016/j.ijmultiphaseflow.2015.06.001

Cited by 47 publications

(16 citation statements)

References 35 publications

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“…Using the workstation it was possible to trigger the X-ray source and read out the signals from the detector plate. Further details on the setup and the measurement technique can be found in [15,16,18]. Each result reported in the present study is an average of 2100 frames (at 35 Hz) of one minute of continuous recording from one source and one detector plate.…”

Section: Methodsmentioning

confidence: 99%

“…To convert the measured attenuation (intensity) to a solids concentration (path length), a calibration protocol that has already been reported in [16] was performed. A dummy calibration module made of identical material (Perspex ® ) and with identical inner diameter (100 mm) and wall thickness (5 mm) as the fluidized bed reactor was constructed (Fig.…”

Section: Image Analysismentioning

confidence: 99%

“…Recently, a detailed study was devoted on the effect of vertically immersed internals on the performance of a lab-scale and a pilot-scale fluidized bed heat exchanger in a real 3D reactor geometry utilizing an ultra-fast X-ray tomography technique [15][16][17]. It was generally found that the immersion of internals results in a lower average bubble size along the fluidized bed.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On the hydrodynamics of membrane assisted fluidized bed reactors using X-ray analysis

Helmi

Wagner

Gallucci

et al. 2017

Chemical Engineering and Processing: Process Intensification

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Section: Methodsmentioning

confidence: 99%

Section: Image Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On the hydrodynamics of membrane assisted fluidized bed reactors using X-ray analysis

Helmi

Wagner

Gallucci

et al. 2017

Chemical Engineering and Processing: Process Intensification

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“…The holdup may increase or decrease depending on the configuration and disposition of the internal tubed. Maurer et al (2015) studied the influence of inner tubes (with outer diameter ranging from 0.01 to 0.02 m) in a 0.14 m column by using x ray tomography. The authors reported a reduction in bubble size for the case with vertical internals.…”

Section: Introductionmentioning

confidence: 99%

Influence of internals on counter-current bubble column hydrodynamics: Holdup, flow regime transition and local flow properties

Besagni

Inzoli

2016

Chemical Engineering Science

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However, in most industrial applications, internal devices are often added to control heat transfer, to foster bubble break-up or to limit liquid phase back mixing. These elements can have significant effects on the multiphase flow inside the bubble column reactor and the prediction of these effects is still hardly possible without experimentation. In this paper, we study experimentally a counter-current gas-liquid bubble column in the open tube and annular gap configurations. In the annular gap bubble column, two vertical internal tubes are considered. The column has an inner diameter of 0.24 m, and the global and local hydrodynamic properties are studied using gas holdup measurements and a double-fiber optical probe. The gas holdup measurements are compared with the literature and used to investigate the flow regime transition. A double-fiber optical probe is used to acquire midpoint data and radial profiles of the local properties to study the flow properties and to further investigate the flow regime transition. The counter-current mode is found to increase the holdup, decrease the bubble velocity and cause regime transition at lower superficial gas velocity. The holdup curves in the annular gap and open tube configurations are similar in shape and values, suggesting that the presence of internals has a limited influence on the global hydrodynamic. In addition, it is found that the presence of the internals stabilizes the homogeneous regime in terms of transition gas velocity and holdup.

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“…Various measurement devices can be used to measure gas holdup in bubble/slurry bubble columns, such as fiber optical probes, conductivity probes, differential pressure probes, ultrasonic techniques, electrical capacitance tomography, X‐ray tomography, gamma‐ray densitometry, and gamma‐ray computed tomography (CT) . However, gamma‐ray computed tomography is superior to other techniques due to its capability to visualize and measure gas holdup over the entire cross‐sectional area of the column in dense and opaque flows that are not visible to other measurement devices due to their limitation to measure in single points (such as probe‐based measurement) or their low penetration capability to pass through the high attenuating material (such as X‐ray tomography) …”

Section: Introductionmentioning

confidence: 99%

Overcoming the gamma‐ray computed tomography data processing pitfalls for bubble column equipped with vertical internal tubes

et al. 2018

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This study identifies and addresses some major pitfalls that are involved in the visualization and quantification of the gas‐liquid distributions and their profiles in a bubble column with internals using the gamma‐ray computed tomography (CT) technique. Some of these pitfalls encountered in the scanning of bubble columns with internals are using an improper reference scan, and applying the same experimental scanning procedure and mathematical relationships for estimating the gas holdup in the column without internals to the column with internals. The experimental results revealed that the selection of the inappropriate reference scan for CT experiments would significantly affect the reconstructed linear attenuation coefficient values and consequently the gas holdup results. Additionally, the reconstructed linear attenuation values showed good agreement with theoretical values when considering air as reference scans. However, disagreement is observed when using the empty column with internals as a reference scan. Moreover, it was found that using the proper reference scan eliminated the errors not only for the reconstructed linear attenuation coefficients but also for the gas holdup values near the wall region. Furthermore, the CT technique was capable of capturing the small thickness (5 mm) of the wall for phantom and bubble columns as well as the internals when the air was used as the reference scan. Finally, a new methodology has been implemented to exclude the internals from the cross‐sectional images, and the azimuthally averaged gas holdup profiles to provide accurate and reliable results for comparison and validation purposes for the bubble column with internals.

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Influence of vertical internals on a bubbling fluidized bed characterized by X-ray tomography

Cited by 47 publications

References 35 publications

On the hydrodynamics of membrane assisted fluidized bed reactors using X-ray analysis

On the hydrodynamics of membrane assisted fluidized bed reactors using X-ray analysis

Influence of internals on counter-current bubble column hydrodynamics: Holdup, flow regime transition and local flow properties

Overcoming the gamma‐ray computed tomography data processing pitfalls for bubble column equipped with vertical internal tubes

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