Fluidization of Group B particles with a rotating distributor

Sobrino, C.; Almendros-Ibáñez, J.A.; Santana, D.; Vega, M. de

doi:10.1016/j.powtec.2007.05.014

Cited by 30 publications

(21 citation statements)

References 21 publications

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“…The fixed bed height (h b ) was varied throughout the experiments between 0.25D and 0.75D. The minimum fluidization velocity was measured to be 0.31 m/s for the rotating distributor bed and 0.33 m/s for the static one, thus the minimum fluidization velocity slightly decreases with the rotation, in agreement with Sobrino et al [24].…”

Section: Methodssupporting

confidence: 85%

“…Sobrino et al [24], using a similar experimental setup to the one used in the present experiments, showed that a rotating distributor may affect global bed parameters. For instance, they showed that, as a consequence of rotation, bubble diameter is affected, and become more homogeneous along the bed and minimum fluidization velocity decreases.…”

Section: Introductionmentioning

confidence: 72%

“…Passive or active control tools are motivated by general drawbacks of BFB, such as poor radial mixing, large bubbles and gas by-pass, or agglomerates and the incidence of heterogeneous fluidization. Proposed solutions include pulsed gas flow ( [17,18]), vibrating beds [19,20], and the use of advanced distributor designs, including spiral [21,22], swirl [23] and rotating distributors [24,25].…”

Section: Introductionmentioning

confidence: 99%

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Motion of a large object in a bubbling fluidized bed with a rotating distributor

Soria-Verdugo

García-Hernando

Almendros-Ibáñez

et al. 2011

Chemical Engineering and Processing: Process Intensification

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a b s t r a c tThis work studies the effect of a low-frequency rotating distributor on the motion of a large object immersed in a bubbling fluidized bed. The object size and density differ from those of the inert solids that conform the bed. Examples of objects moving in a bubbling fluidized bed include passive particles, catalysts and reactants. The rotation modifies the bed dynamics in the surroundings of the distributor and affects the motion of the object within the bed.A set of experiments was carried out in a lab-scale cylindrical bed, equipped with a perforated plate distributor that can rotate at around 1 Hz, for different bed aspect ratios, gas velocities, and object characteristics. Sizes were far larger than that of the solids of the dense phase and densities ranged from half the bed density to values around it. The experiments were video recorded, capturing the surface of the bed from above.As have often been noted, objects might remain in stagnant regions near the distributor and be "lost" or precluded to circulate. This can be avoided in most practical cases forcing the distributor to rotate. Also, the effect of rotation on the circulation time of the objects is presented, showing a general reduction of large circulation times.

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Section: Methodssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

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Motion of a large object in a bubbling fluidized bed with a rotating distributor

Soria-Verdugo

García-Hernando

Almendros-Ibáñez

et al. 2011

Chemical Engineering and Processing: Process Intensification

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“…3. In addition to the 2D measurements, several measurements were obtained from a 3D bed that was similar to the one described in the literature [31]. These data were used to obtain the minimum fluidization velocity in a 3D bed.…”

Section: Experimental Set-upmentioning

confidence: 99%

On the minimum fluidization velocity in 2D fluidized beds

et al. 2011

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a b s t r a c tIn the present study, a new correlation for the determination of the minimum fluidization velocity in 2D fluidized beds was developed. The proposed correlation was based on the experimental results obtained in 2D fluidized beds with different particle sizes, bed thicknesses and bed heights. Thus, the proposed correlation depends only on the nondimensional variable t/d p , where t is the bed thickness and d p is the particle size. The proposed correlation was compared with other experimental results that can be found in the literature, and two different trends were observed. Namely, one set of experimental results was in accordance with the proposed correlation, while the other set deviated from the theoretical results. In particular, the minimum fluidization velocities of the experimental results were greater than the predicted values of the proposed correlation. In view of the differences in the experimental conditions, the observed discrepancies may be attributed to the effects of electrostatic charge and particle shape. In addition, the experimental fluidization defluidization curves were compared to the theoretical results of Jackson's model, and the parameters were fitted to the experimental data. However, Jackson's model is based on a 1D bed; thus, general parameters could not be obtained for a bed with a fixed particle size and thickness due to the two dimensional voidage distribution in the bed and bed cohesion effects, which are a result of electrostatic forces and are not considered in Jackson's model.

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“…It has been previously reported that the rotating distributor motion promotes an increase in the radial dispersion of particles, preventing the temperature gradients by reducing high particle concentration zones present within fluidized beds [19,20]. Furthermore, there is some experimental evidence that the stagnant zones just above the distributor could be broken by the rotating distributor, improving the radial and axial mixing at the bottom of the bed [21].…”

Section: Introductionmentioning

confidence: 99%

Fluidized bed with a rotating distributor operated under defluidization conditions

Gómez-Hernández

Soria-Verdugo

Briongos

et al. 2012

Chemical Engineering Journal

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h i g h l i g h t sThe capability of a rotating distributor to recover a defluidized bed was analyzed. Defluidization was reached by injecting a punctual volume of water on the bed surface. Fluidization and recovery processes were analyzed in the time and frequency domain. An excellent agreement was found for the time and frequency domain results. The rotating distributor improves the fluidization quality of a defluidized bed. Keywords: Fluidized bed Liquid injection Defluidization Rotating distributor a b s t r a c tThe fluidization conditions of a rotating distributor applied to a 3-D bubbling fluidized bed was studied to assess its potential use as a counteracting measure of defluidization phenomena. The performance of the fluidized bed operating under nominal conditions was characterized for the rotating and the static distributor configuration. Different methods of analysis in the time and frequency domain were applied to establish the performance of the fluidized bed. The frequency domain analysis suggests some kind of local structuring of fluidized bed dynamics imposed by the distributor motion. The punctual injection of water over the surface of the bed lead to a high cohesive wet region that tend to settle down on top of the distributor giving rise to defluidization. The water-induced defluidization tests reflect an improvement of the fluidization quality with the distributor rotation.

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Fluidization of Group B particles with a rotating distributor

Cited by 30 publications

References 21 publications

Motion of a large object in a bubbling fluidized bed with a rotating distributor

Motion of a large object in a bubbling fluidized bed with a rotating distributor

On the minimum fluidization velocity in 2D fluidized beds

Fluidized bed with a rotating distributor operated under defluidization conditions

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