Favorable vibrated fluidization conditions for cohesive fine particles

Mawatari, Yoshihide; Tsunekawa, Masaya; Tatemoto, Yuji; Noda, Katsuji

doi:10.1016/j.powtec.2005.04.026

Cited by 27 publications

(14 citation statements)

References 20 publications

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“…The addition of mechanical vibration to the fluidized bed is expected to break the agglomerates and stable gas channels. Many reports about the vibrating fluidization behavior can be seen up to now [9][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Flow Pattern Transition of Fine Cohesive Powders in a Gas-Solid Fluidized Bed under Mechanical Vibrating Conditions

Mawatari

Hamada

Yamamura

et al. 2015

Procedia Engineering

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In this study, the fluidization characteristics for fine cohesive powders under mechanical vibrating conditions were experimentally investigated. In a case of handling of fine cohesive powders with fluidized bed, stable gas channels and cracks were easily formed in the bed due to the strong cohesiveness acting among particles. A mechanical vibration is one of the methods to improve the fluidity of fine cohesive powders. In this study, we focused on the transition of the dominant bed flow pattern induced by mechanical bed vibrating conditions. The powders used in this study were different sizes (0.7 -20μm) and materials (silica, alumina, polymer). All powders belonged to group-C in the Geldart classification. The bed expansion ratio was lower in the relatively smaller vibration strengths regardless of the gas velocity, however, it steeply increased with larger a certain vibration strength. Form the visual observation of the bed, the bubble formation appeared with larger than such a critical vibration strength. This implied that the dominant bed fluidization pattern was transitioned from channeling behavior (group-C) to bubbling behavior (group-A or -AC) by the addition of the mechanical vibration.

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Section: Introductionmentioning

confidence: 99%

Flow Pattern Transition of Fine Cohesive Powders in a Gas-Solid Fluidized Bed under Mechanical Vibrating Conditions

Mawatari

Hamada

Yamamura

et al. 2015

Procedia Engineering

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“…The fluidization characteristics of Al 2 O 3 particles were investigated via a de-fluidization experiment, which is less susceptible to inter-particle forces [ 20 ]. In the experiment, after filling the dispersion vessel with Al 2 O 3 particles, vertical vibration was applied to simultaneously supply fluidized air and secondary air at the bottom of the powder bed to fluidize the powder bed for 5 min.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…There is much research on vibrating fluidized powder beds [ 19 , 20 , 21 , 22 , 23 , 24 ]. These studies have investigated the flow pattern [ 20 , 24 ] and flow characteristics [ 19 , 20 , 21 , 22 , 23 , 24 ] to the particulate materials of micron- and nano-size when the vibrating amplitude, frequency, and fluidized air velocity are changed. Regarding the particle dispersion in the vibrated powder bed, there is also an experimental study of the release of dust from cohesive powder by vibrating fluidization [ 25 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

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Characteristics of Vibrating Fluidization and Transportation for Al2O3 Powder

et al. 2022

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This study focused on the vibrating fluidized-bed-type powder feeder used in HVAF thermal spraying equipment. This feeder has been used in thermal spraying equipment and industrial applications. However, particulate materials’ flow mechanism and stable transport characteristics have not been fully understood. This study experimentally investigated the fluidization characteristics, powder dispersion state, and powder transportation characteristics of Al2O3 particles during vertical vibration fluidization. The material used was Al2O3 particles of 2.9 μm and 3808 kg/m3, classified as the group C particles in the Geldart diagram. As experimental conditions, the fluidized air velocity to the bottom of the powder bed and the vibration intensity in the vertical direction changed. The critical fluidization air velocity was defined to evaluate the generating powder flow by vertical vibrating fluidization. As a result, good fluidization of the powder bed of Al2O3 was obtained by the vertical vibration, as well as an airflow that was higher than the critical fluidization air velocity. Regarding powder transportation characteristics, it was clarified that the fluidized air velocity at the bottom of the powder dispersion vessel and the pressure difference from the powder dispersion vessel to the transportation part significantly affect the mass flow rate.

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“…It is well-known that fine power belongs to group C in Geldart’s classification, which is difficult to be fluidized or conveyed because of the considerable interparticle forces, such as London–van der Waals, electrostatic interactions and liquid bridging forces. , The interparticle forces put forward many problems in the fluidization and entrainment of group C particles, such as channeling, slugging, and spouting . A series of methods have been developed to improve the fluidization characteristics, including addition of coarse particles, , fine powder coating, vibration, − agitation, sound waves, , and magnetic and electric fields . In this work, a combination of vibration, agitation, and coarse particles was introduced into fluidized bed feeder, and the effects on entrainment characteristics were investigated.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Entrainment Characteristics of Ultrafine Powder in a Fluidized Bed with Vibrator and Agitator

Wang

Yin

et al. 2013

Ind. Eng. Chem. Res.

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The entrainment characteristics of Geldart group C powder from solid mixtures (groups A and C) were investigated in a fluidized bed (inner diameter of 40 mm and height of 150 mm) equipped with two vibrators and an agitator. Silicon powders of mean size 2.2 and 0.9 μm were adopted as entrained material (group C), hollow alumina pellets of mean sizes 359, 505, 650, 775, 996, and 1200 μm were used as coarse particles (group A), and industrial nitrogen was applied as carrier gas. At ambient temperature (20 °C) and atmospheric pressure, the effects of the size of coarse particles (D, 359–1200 μm), mass ratio of coarse to fine particles (M, 0–1.5), ratio of static bed height to diameter (H, 0.875–1.625), rotational speed of agitator (ω, 27–54 rps), vibration intensity (Γ, 0–5.0) and superficial velocity of nitrogen gas (V, 0.22–0.55 m/s) on the entrainment characteristics were experimentally studied in sequence. In the scope of this work, the increase of M, Γ, or V could always improve the entrainment characteristics, while there exists an optimal value for D, H, or ω to obtain the optimum entrainment characteristics. The entrainment rate constant is an order of magnitude larger than that without vibration and agitation, which shows the significant effects of vibration and agitation on the improvement of entrainment characteristics. A relational expression is derived to unify the experimental data, which gives a good fitting result.

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Favorable vibrated fluidization conditions for cohesive fine particles

Cited by 27 publications

References 20 publications

Flow Pattern Transition of Fine Cohesive Powders in a Gas-Solid Fluidized Bed under Mechanical Vibrating Conditions

Flow Pattern Transition of Fine Cohesive Powders in a Gas-Solid Fluidized Bed under Mechanical Vibrating Conditions

Characteristics of Vibrating Fluidization and Transportation for Al2O3 Powder

Experimental Study on the Entrainment Characteristics of Ultrafine Powder in a Fluidized Bed with Vibrator and Agitator

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