Demonstrating the non-similarity in local holdups of spouted beds obtained by CT with scale-up methodology based on dimensionless groups

Ali, Neven; Al-Juwaya, Thaar; Al‐Dahhan, Muthanna H.

doi:10.1016/j.cherd.2016.08.010

Cited by 20 publications

(28 citation statements)

References 47 publications

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“…The gas flow rates were measured using the two rotameters and gas flow was introduced into the spouted beds through the inlet orifice (gas distributor). To maintain stable spouting in spouted beds, the conditions of the experiments used in [13] were followed.…”

Section: Experimental Work 21 Spouted Beds Setupmentioning

confidence: 99%

“…Recently, Ali et al [13] studied the local solids and gas holdup distributions along the bed height using gamma-ray computed tomography (CT) technique which measures time averaged crosssectional distribution of phases densities and hence holdups. Also, Aradhya [14] investigated the local solids holdup and velocity in spouted beds using sophisticated and newly developed optical fiber probes which measure the point measurements of both solids velocity and solids concentrations (holdups with a proper calibration).…”

Section: Introductionmentioning

confidence: 99%

“…Aradhya [14] demonstrated the dissimilarity using limited local point measurements of solids velocity and holdup by implementing an optical fiber probe when the proposed dimensionless groups of [15] were matched. Recently, Ali et al [13] used gamma-ray computed tomography (CT) to assess such [15] scale-up methodology and also found that the similarity of solids and gas holdups cross-sectional distribution and their radial profiles along the bed height was not achieved by matching the proposed dimensionless groups. Following the work of [15], studies have been conducted in the literature to expand upon the dimensionless-group-based scale-up approach of spouted beds by adding the restitution coefficient (e ss ) of particles to the set of dimensionless groups proposed by [15], [17,18].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An advanced evaluation of spouted beds scale-up for coating TRISO nuclear fuel particles using Radioactive Particle Tracking (RPT)

Ali

Al-Juwaya

Al‐Dahhan

2017

Experimental Thermal and Fluid Science

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A set of dimensionless groups has been proposed in the literature by He et al. [He Y. L., Lim C. J., Grace J. R., Scale-up studies of spouted beds, Chemical Engineering Science, 52 (2), 329-339, 1997] to scale-up gas-solid spouted beds while maintaining their hydrodynamics similarity. The literature reported studies do not provide conclusive assessments about this methodology. Therefore, in this work, we have applied an advanced non-invasive radioactive particle tracking (RPT) technique for the first time to evaluate such scale-up methodology by measuring the local solids velocity, normal and shear stresses and the turbulent kinetic energy. The axial and azimuthal averaged radial profiles of solids velocity, normal stresses, shear stresses, and turbulent kinetic energy illustrate that the similarity of the hydrodynamics has not been attained when the proposed set of dimensionless groups has been matched using two sizes of spouted beds of 0.076 m and 0.152 m and sets of operating conditions. The conclusion is consistent with the recent reported findings by measuring cross sectional distribution and radial profiles of solids and gas holdups along the bed height using gamma-ray computed tomography and by the limited point measurements of solids velocity and holdup using optical fiber probe. It is clear that local measurements of hydrodynamic parameters are essential for detailed assessment of scale-up methodologies. The presented results of our work in terms of the components profiles of the particles radial velocities and turbulent parameters are also valuable for benchmarking computational fluid dynamics codes and models.

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Section: Experimental Work 21 Spouted Beds Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An advanced evaluation of spouted beds scale-up for coating TRISO nuclear fuel particles using Radioactive Particle Tracking (RPT)

Ali

Al-Juwaya

Al‐Dahhan

2017

Experimental Thermal and Fluid Science

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“…The kinetic model using these parameters conducted to relative errors of 3.25 % and 3.98 % for HDS and HDN conversion when compared with experimental values (which had the highest error margin of 0.3 wt%).…”

Section: Theorymentioning

confidence: 99%

“…In our previous work, we implemented a study comparing columns with different relations between length and diameter (L R /D R ) and reactor diameter to pellet diameter ( N = D R /d P ). It was observed that to ensure a similar hydrodynamic behaviour inside two packed columns of different dimensions, the liquid holdups between both columns should be equalized . This kind of equality, combined with a model that incorporates a rigorous description of the void fraction of the bed and considers an adequate closure for the interfacial momentum exchange model (IMEM), has led to predictions of pressure drops with an error that is down to 1.9 %, which implies a 50 % improvement in holdup predictions and up to 5 times better accuracy in pressure drops.…”

Section: Introductionmentioning

confidence: 99%

CFD analysis of bed textural characteristics on TBR behaviour: Kinetics, scaling‐up, multiscale analysis, and wall effects

Uribe¹,

Cordero²,

Zárate³

et al. 2018

Can J Chem Eng

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A simulation of a trickle bed reactor aided by computational fluid dynamics was implemented. With a Eulerian approach, geometrical characteristics were explicitly considered and two simultaneous heterogeneous reactions were included, hydrodesulphurization (HDS) and hydrodenitrogenation (HDN). This was performed in order to achieve the following: (1) attain further insight into a proper scaling‐up procedure to be able to obtain the same hydrodynamics and kinetics behaviour in two reactors of different length and diameter scales; (2) develop a multiscale analysis regarding the communication of information between scales through the construction of a porous microstructure model from which the geometrical information of the microscale is captured by the effective transport coefficients (which affect the overall reactor behaviour); (3) investigate the effect of operation condition variations on hydrodynamics and kinetics; and (4) assess the deviations and further differences observed from average to punctual conversion values and the assumptions from kinetic literature models through a preliminary multiscale analysis. The CFD results were validated against experimental pressure drop data as well as HDS and HDN conversion theoretical data. An excellent agreement was found. The model produces a significant improvement in hydrodynamic parameter prediction, achieving 5 times better accuracy in predicting pressure drops and 50 % improvement in holdup prediction. The fully coupled model predicts HDS conversion with 96 % accuracy and HDN conversion with 94 % accuracy. Results suggest that the best way to obtain similar kinetic and hydrodynamic behaviour in TBRs with different lengths and diameter length scales is by equaling the liquid holdup true(ϵγtrue) or the mass velocities (L‐G).

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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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Demonstrating the non-similarity in local holdups of spouted beds obtained by CT with scale-up methodology based on dimensionless groups

Cited by 20 publications

References 47 publications

An advanced evaluation of spouted beds scale-up for coating TRISO nuclear fuel particles using Radioactive Particle Tracking (RPT)

An advanced evaluation of spouted beds scale-up for coating TRISO nuclear fuel particles using Radioactive Particle Tracking (RPT)

CFD analysis of bed textural characteristics on TBR behaviour: Kinetics, scaling‐up, multiscale analysis, and wall effects

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

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