PIV investigations of flow structures in the fluidised bed freeboard region

Duursma, Gail; Glass, Donald; Rix, S. J. L.; Yorquez-Ramirez, M. I.

doi:10.1016/s0032-5910(01)00340-0

Cited by 32 publications

(22 citation statements)

References 6 publications

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“…Overall, the favoured ascending gas channels within a bubbling fluidised bed varies not only with bed geometry and the ratio of bed height to bed diameter as described in literature [22,40], but also appears to vary with bed materials and superficial gas velocity. Under the similar operation conditions, different bed materials give a different gas/solid flow pattern.…”

Section: Bubble Flow Patternsmentioning

confidence: 70%

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Prediction of bubble behaviour in fluidised beds based on solid motion and flow structure

Fan

Yang

Parker

et al. 2008

Chemical Engineering Journal

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Section: Bubble Flow Patternsmentioning

confidence: 70%

“…A literature search shows that solid flow patterns in bubbling fluidised beds vary mainly with the bed height [22,40]. When the ratio of the bed height to the bed diameter is unity, the solid travels upwards either along the annulus or along the central part of the bed, inducing two circulation cells within the whole bed.…”

Section: Solid Flow Patternsmentioning

confidence: 99%

Prediction of bubble behaviour in fluidised beds based on solid motion and flow structure

Fan

Yang

Parker

et al. 2008

Chemical Engineering Journal

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“…When a bubble erupts at the bed surface, it projects particles into the freeboard, although the particles' necessary to understand the process being undergone below it, namely, the formation and disintegration of coherent structures like clusters, vortex or ghost bubbles, as well as the interaction between the particles and the gas turbulence (Pemberton and Davidson, 1984;Duursma et al, 2001;Solimene et al, 2004). These processes are influenced by bubble eruption, the projection and velocity of the ejected particles and the maximum height they reach.…”

Section: Introductionmentioning

confidence: 99%

A new model for ejected particle velocity from erupting bubbles in 2-D fluidized beds

Almendros-Ibáñez

Sobrino

Vega

et al. 2006

Chemical Engineering Science

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A new model is proposed for obtaining the velocity profile of the particle ejected from the bubble dome in a freely bubbling 2-D fluidized bed. Its basis is the supposition that the initial velocity of the ejected particles, with a direction perpendicular to the dome contour, depends on bubble velocity and bubble growth velocity. This model differs from those previously appearing in the literature in that it is valid not only for vertical-ascent circular bubbles.Experiments were carried out in a freely bubbling 2-D fluidized bed using a high-speed video camera to measure the velocity profile. Upon comparing these results with the proposed model, it was established that, excepting some isolated cases, the model properly predicts the magnitude and direction of the maximum particle ejection velocity and the velocity profile.Using the work of Shen et al. (2004. Digital image analysis of hydrodynamics two-dimensional bubbling fluidized beds. Chemical Engineering Science 59, 2607-2617), we obtain two general equations for the bubble velocity and the bubble growth velocity in a 2-D fluidized bed. These expressions, together with the proposed model, can be used to calculate the initial velocity of the ejected particles.

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“…The experiments were restricted to the determination of the gas field in the freeboard above an erupting bubble but far from the bed surface. Yó rquezRamírez and Duursma [14,15] and Duursma et al [16] studied the air flow pattern above an erupting bubble in an incipiently fluidized bed, showing the applicability of PIV techniques to obtain the continuous phase flow fields in fluidized beds.…”

Section: Introductionmentioning

confidence: 99%

Initial particle velocity spatial distribution from 2-D erupting bubbles in fluidized beds

et al. 2005

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Some results on particle image velocimetry (PIV) in 2 D freely bubbling fluidized beds are presented. The PIV applications were used in order to determine the initial particle velocity of bubble eruptions. A two dimensional non reacting fluidized bed was constructed to measure the origin of the ejected particles and the initial particle velocity distribution, using coarse sand particles. The bubble ejection mechanism was observed taking into account the origin of particles ejected, the initial particle velocity distributions as well as the effect of other neighbor exploding bubbles. Our results show that the assumption of linear dependence of initial velocity with the angle predicts the velocity faithfully only for purely vertical ascent bubbles. Measurements of ejection velocities show that initial velocities in the combined layer are higher than those of the particles in the nose of the leading bubble. Avoiding coalescence of bubbles at the bed surface can lead to less particle entrainment out of the bed and consequently to shorter fluidized beds.

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PIV investigations of flow structures in the fluidised bed freeboard region

Cited by 32 publications

References 6 publications

Prediction of bubble behaviour in fluidised beds based on solid motion and flow structure

Prediction of bubble behaviour in fluidised beds based on solid motion and flow structure

A new model for ejected particle velocity from erupting bubbles in 2-D fluidized beds

Initial particle velocity spatial distribution from 2-D erupting bubbles in fluidized beds

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