The solids flow in the CFB-riser quantified by single radioactive particle tracking

Mahmoudi, Shiva; Baeyens, Jan; Seville, Jonathan

doi:10.1016/j.powtec.2011.04.011

Cited by 37 publications

(24 citation statements)

References 62 publications

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“…Clearly, the occurring choking regime is specifically important at high values of G and/or low values of ( − TR ). An inaccuracy of 0.2 m/s was indicated with respect to TR predictions from (5).…”

Section: Resultsmentioning

confidence: 94%

“…Having established a correlation for Ch in terms of gas and solids properties, the "work" diagram of Mahmoudi et al [5,6] can be adapted, as illustrated in Figure 6. Clearly, the occurring choking regime is specifically important at high values of G and/or low values of ( − TR ).…”

Section: Resultsmentioning

confidence: 99%

“…Bi and Fan [10] Ch √ = 21.6( The objective of the present research hence considered (i) the delineation of the choking phenomenon in different riser geometries and using different A-type powders, (ii) the comparison of experimental results with the empirical predictions of (1)-(4), and finally (iii) the adaptation of the proposed operation diagram of Mahmoudi et al [5,6] to include the ( , ) region subject to choking.…”

Section: Literature Correlations To Predict Choking Velocitiesmentioning

confidence: 99%

“…First approaches to develop a "work map" of the riser operation were presented by, for example, Grace [1], Yerushalmi and Avidan [2], and Bai et al [3]. It was further developed by Chan et al [4] and Mahmoudi et al [5,6] for both Geldart A-and B-type powders: the operating gas velocity ( ) and the solids circulation flux ( ) jointly delineate different regimes, called, respectively, dilute riser flow (DRF), core-annulus flow (CAF) (possibly with a turbulent fluidized bed at the bottom of the riser (TFBB)), and dense riser upflow (DRU). For a given powder and its associated transport velocity, TR , the combination of and will determine the flow regime encountered.…”

Section: Introductionmentioning

confidence: 99%

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Choking Affects the Operation Diagram of a CFB Riser

Zhang

Degrève

Baeyens

et al. 2014

Journal of Powder Technology

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Experiments in 3 different CFB risers have confirmed that common riser operations can be hampered in a well-defined (U, G) range where choking occurs. Geldart A-type powders were investigated. Experimental results of the choking velocity were empirically correlated, being about 30% lower than predicted by the correlation of Bi and Fan, but largely exceeding other predictions. Introducing the findings into the operation diagram presented by Mahmoudi et al. adds a region where stable riser operation is impossible. The adapted diagram enables CFB designers to better delineate the operating characteristics.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Literature Correlations To Predict Choking Velocitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Choking Affects the Operation Diagram of a CFB Riser

Zhang

Degrève

Baeyens

et al. 2014

Journal of Powder Technology

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“…As the key part of a CFB, the riser provides a place for the circulation of the reacting gas/solid substances . In order to keep sufficient dense suspension in the riser, particles are continuously collected from the exit and recycled to the base . Provided the riser is long enough, fully developed flow conditions will be formed, and the solids hold‐up will be approximately invariant with the changes of axial heights.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic investigation on gas–solid two‐phase flow character in a circulating fluidized bed

Wang

Fan

Lei

et al. 2013

Asia-Pacific J Chem Eng

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Riser is the key component of circulating fluidized bed reactors, in which gas-solid or catalytic reactions occurs. The flow hydrodynamics and Geldart B type solids' concentration profiles in the riser, under higher superficial gas velocity, larger solids circulation rate, and wide ranges of operating conditions, were the focuses of this experimental study. The typical core-annulus structure with clusters and a small amount of particles' back-mixing phenomena near the wall of the riser was observed. The axial solids concentration distributions in the riser with an abrupt T-shape exit were characterized by a dense region near the bottom, a dilute region toward the up-middle zone, and a dense region near the top exit. Solids became dilute, and the back-mixing phenomena weakened with the increase of superficial gas velocity. And the solids concentration at the same height position increased with the increment of solids circulation rate. Furthermore, the effects of two exit configurations, namely smooth C-shape and abrupt T-shape, on the flow characteristics were investigated. In order to compare the influence of particles' density and diameter, four single Geldart D particles and a soybean and millet two-phase mixture are chosen as bed materials to study the bubbling bed flow character.

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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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The solids flow in the CFB-riser quantified by single radioactive particle tracking

Cited by 37 publications

References 62 publications

Choking Affects the Operation Diagram of a CFB Riser

Choking Affects the Operation Diagram of a CFB Riser

Hydrodynamic investigation on gas–solid two‐phase flow character in a circulating fluidized bed

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

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