Flow regimes and vertical solids conveying in a spout‐fluid bed with a draft tube

Nagashima, Hiroshi; Ishikura, Toshifumi; Ide, Mitsuharu

doi:10.1002/cjce.20403

Cited by 28 publications

(7 citation statements)

References 30 publications

(44 reference statements)

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“…This requires more fluidizing gas, which leads to an increase in minimum spouting fluidizing gas velocity. This implies that more gas flow is needed to form a fountain at the end of the draft tube, similar to the results in Nagashima et al for a conical base spout‐fluid bed with a draft tube. As described previously, the change in minimum spouting fluidization velocity is very significant for large static beds compared to lower bed heights.…”

Section: Resultssupporting

confidence: 92%

Experimental investigation of hydrodynamics of gas‐solid flow in an internally circulating fluidized bed

Gujjula

Mangadoddy

2015

Can J Chem Eng

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Hydrodynamic study of gas and solid flow in an internally circulating fluidized bed (ICFB) is made in this paper using a high-speed camera and pressure probes for the laboratory 0.3 m Â 0.27 m column having an internal draft tube. Experiments were conducted using sand particles of Geldart B and Geldart B-D groups. At each run the standard pressure-flow curves for both the draft tube and annular region beds, and the moving wall particle velocity in the annular bed region were measured. The effects of superficial gas velocity, static bed height, and draft tube gap height on pressure drop profiles, solid circulation patterns, and gas bypassing dynamics for the ICFB were investigated extensively. Unlike the conventional CFB, the pressure drop in ICFB is further decreased with superficial gas velocity after the minimum spouting fluidization, followed by yielding a crossover in the pressure drop of the annular bed compared to the draft tube. Pressure drop in the draft tube increases with an increase of static bed height and gap height between the draft tube bottom and the air distributor. The gas bypassing fraction increases with an increase in gap height and decreases with increased bed height and mean particle size. The mechanism governing the solid circulation and the pressure losses in an ICFB has been elaborated based on gas and solid dynamics obtained from the experimental data.

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Section: Resultssupporting

confidence: 92%

Experimental investigation of hydrodynamics of gas‐solid flow in an internally circulating fluidized bed

Gujjula

Mangadoddy

2015

Can J Chem Eng

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“…Many studies have been made in the past in order to better understand the hydrodynamic behaviours of the spout bed and the spout‐fluid bed with or without a draft tube. San José et al compared the bed stability of conical spouted beds for stable operation with and without a draft tube, and reported that the unstable spouted‐bed state is not reached at any stagnant bed height with a draft tube, and stated that the minimum spouting velocity is much lower.…”

Section: Introductionmentioning

confidence: 99%

Effect of bed geometry on operating pressure drop and minimum fluidizing velocity in a draft tube spout‐fluid bed

Zhang

Huang

et al. 2019

Can J Chem Eng

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Operating pressure drop and minimum fluidizing velocity were studied in a flat spout-fluid bed using sub-millimetre grade silicon particles. The influence of introducing a nonporous draft tube of different configurations as well as fluidizing gas on the two parameters was investigated. A comparison of fluidizing gas systems indicated that introduced gas restrained gas bypassing to lower the minimum fluidizing velocity; however, the operating pressure drop was higher than systems without the existence of fluidizing gas. Two new correlations that took into account the effects of bed geometry and fluidizing gas on the operating pressure drop and minimum fluidizing velocity were developed based on the experimental data, which were in agreement with the present experiments.

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“…In view of its excellent performance and widespread application, numerous experimental efforts have unsurprisingly focused on various aspects of this apparatus, spanning the hydrodynamics, solid circulation, particle velocity profile, pressure drop and fluctuation, flow reigme, maximum bed height, particle mixing, minimum spouting velocity, effect of draft plates, thermal behavior, and so on. In tandem with experimental investigations, the numerical simulation of the dense two‐phase flow has progressed too.…”

Section: Introductionmentioning

confidence: 99%

CFD–DEM investigation into the scaling up of spout‐fluid beds via two interconnected chambers

et al. 2016

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The hydrodynamics and chamber interaction in a three-dimensional spout-fluid bed with two interconnected chambers are investigated via computational fluid dynamics coupled with discrete element method (CFD-DEM), because multiple interconnected chambers are key to scaling up spout-fluid beds. The overall solid motion, spouting evolution, and spoutannulus interface is studied, followed by time-averaged hydrodynamics, particle-scale information, spout-annulus interaction, and inter-chamber interaction. The results show that inter-chamber interactions lead to unique characteristics distinct from that for a single-chamber system, including (1) asymmetry of the hydrodynamics within each chamber, (2) alternative spouting behavior in the two chambers, (3) smaller pressure drop in terms of magnitude and fluctuations, (4) two peaks in the solid residence time (SRT) frequency histogram of the annulus, (5) average SRT in the spout is twice that in a single-chamber, and (6) larger solid dispersion in all three directions. The results provide meaningful understanding for the scale-up of spout-fluid beds.In view of its excellent performance and widespread application, numerous experimental efforts have unsurprisingly focused on various aspects of this apparatus, spanning the hydrodynamics, 11,12 solid circulation, 13,14 particle velocity profile, 15 pressure drop 16 and fluctuation, 17 flow reigme, 18-20 maximum bed height, 21 particle mixing, 22 minimum spouting velocity, 23 effect of draft plates, 24-26 thermal behavior, 27 and so on. In tandem with experimental investigations, the numerical simulation of the dense two-phase flow has progressed too. As is well-acknowledged, two approaches, namely, the twofluid model (TFM) and computational fluid dynamics combined with discrete element method (CFD-DEM), are available to model the dense gas-solid flow. 28,29 The critical difference between these two approaches lies in the resolution of the solid motion: the solid phase is treated as a continuum and tracked individually in the Lagrangian framework in TFM and CFD-DEM, respectively. Zhong et al. 30 numerically explored the gas/solid flow in the three-dimensional (3-D) spout-fluid bed using TFM, wherein the kinetic theory of granular flow provided the closures. The results demonstrated that the simulation results are strongly affected by the restitution

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Flow regimes and vertical solids conveying in a spout‐fluid bed with a draft tube

Cited by 28 publications

References 30 publications

Experimental investigation of hydrodynamics of gas‐solid flow in an internally circulating fluidized bed

Experimental investigation of hydrodynamics of gas‐solid flow in an internally circulating fluidized bed

Effect of bed geometry on operating pressure drop and minimum fluidizing velocity in a draft tube spout‐fluid bed

CFD–DEM investigation into the scaling up of spout‐fluid beds via two interconnected chambers

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