On the electrostatic equilibrium of granular flow in pneumatic conveying systems

Ye, Jun; Zhang, Yan; Wang, Chi-Hwa; Liang, Yung C.

doi:10.1002/aic.10991

Cited by 59 publications

(38 citation statements)

References 34 publications

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“…Other pertinent simulation parameters are presented in Table 1. Values of fluidizing velocities were selected to be consistent with a recent study by Lim et al 23 so that direct comparisons of fluidization and mixing behaviors of particles in fluidized bed 25 so as to obtain physically realistic simulations of charged particles and container walls. In all simulations performed, particles were first allowed to settle freely under gravity for 0.5 s and form a packing at the bottom of the container before fluidizing air was initiated.…”

Section: ■ Computational Modelmentioning

confidence: 98%

Mixing Behaviors of Granular Materials in Gas Fluidized Beds with Electrostatic Effects

Lim

2013

Ind. Eng. Chem. Res.

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The discrete element method combined with computational fluid dynamics was coupled to an electrostatic force model for computational studies of mixing behaviors in gas fluidized bed systems with electrostatic effects. Due to the presence of strong electrostatic forces between particles and walls, there was a high tendency for particles to be adhered to the walls or other particles near the walls within the fluidized bed, resulting in less vigorous fluidization. This in turn resulted in lower mixing efficiencies in comparison with fluidization in the presence of weaker electrostatic effects. Particle−wall electrostatic forces were on average stronger than both fluid drag forces and particle−particle collision forces when strong electrostatic effects were present, and this accounted for the difficulty with which particles adhered to walls could be removed and transferred to other locations within the bed. Such transfers of particles were necessary for mixing to occur during fluidization but required strong electrostatic forces to be overcome. ■ INTRODUCTIONTriboelectrification is the process of charge acquisition by solid particulate materials during flows due to repeated collisions between the solid particles with surfaces made of a different material. 1 It is an important phenomenon that arises in various environmental and industrial processes especially those that involve bounded flows of granular materials. The amount of charge transferred between two contacting bodies during impact depends on the potential difference between the two bodies, which in turn depends on their surface work functions and the image charge effect. 2 In recent years, the behaviors of granular materials under the effects of electrostatics have been investigated by several researchers. Al-Adel et al. 3 investigated the effect of static electrification on gas−solid flows in vertical risers and captured various qualitative features of riser flows. Matsusaka et al. 4 developed a formulation for the variation of granule charging caused by repeated impacts on a wall and employed the formulation to granule charging in granular flows where each granule carried a different amount of charge. They then analyzed theoretically the granule charge distribution. Lim et al. 5 coupled the discrete element method (DEM) with large eddy simulation (LES) and an electrostatic force model for computational studies of pneumatic transport of granular materials in the presence of electrostatic effects. They observed that electrostatic and fluid drag forces were important in influencing particle behaviors during pneumatic transport at low and high flow rates respectively. Tanoue et al. 6 investigated triboelectrification of particles fed by an ejector into a turbulent pipe flow and observed an unusual charge transfer which could not be accounted for solely by contact potential difference. They suggested that the charge transfer consisted of adsorption of ions on the inner wall of the pipe in addition to ionization by self-discharge. Bunchatheeravate et al. 7 develo...

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Section: ■ Computational Modelmentioning

confidence: 98%

Mixing Behaviors of Granular Materials in Gas Fluidized Beds with Electrostatic Effects

Lim

2013

Ind. Eng. Chem. Res.

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“…Yao [14] carried out a comprehensive study of the granular size and shape effect on electrostatics in continuous recycled pneumatic conveying systems. Yao [15] also integrated various instruments including electrometers, electrical capacitance tomography (ECT) and particle image velocimetry (PIV) to characterize granular behavior and figure out the "electrostatic equilibrium state" for a pneumatic conveying system.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Electrostatic Charge Generation for Granules

Zhou

Yin

et al. 2015

Procedia Engineering

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In studies of granule electrification due to sliding, quantitatively evaluating the charging characteristic of single particles, rather than of a mass of granules as a group, is important for a fundamental understanding of the elementary tribocharging phenomenon, which is complicated, since it is resulted from electrical and physical properties of granules and operational environment conditions. In this work, charge transfer due to a single particle repeated sliding along metal plane for Polyvinyl Chloride(PVC)granules(diameter 1.1-4.1 mm, in the shape of halfcircle or rectangle). The amount of transferred charge is expressed as a function of granular shape factor, such as length-ratio, sliding area, front-facing edge, as well as sliding velocity, plane angle and relative humidity. The transferred charge increases with length-ratio and area. Front-facing edge, plane angle, sliding velocity and relative humidity do have effect on the degree of electrification.

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“…Until now, majority of the work was involved in developing the understanding on the tribo-charging mechanism [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49]. Several studies were also carried out to know the tribocharging characteristics in pneumatic conveying [50][51][52][53][54][55][56][57][58][59][60][61][62][63] and gassolid fluidized bed system [64][65][66][67]. Different types of tribo-chargers such as vibratory feeder, cyclone, fluidized bed, pneumatically conveying through pipe were developed so that the target and reject particulates could attain higher differential charge during contact electrification [14,17,18,[68][69][70][71][72].…”

Section: Introductionmentioning

confidence: 99%

Studies on the effect of electrode plate position and feed temperature on the tribo-electrostatic separation of high ash Indian coking coal

Dwari

Mohanta

Rout

et al. 2015

Advanced Powder Technology

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On the electrostatic equilibrium of granular flow in pneumatic conveying systems

Cited by 59 publications

References 34 publications

Mixing Behaviors of Granular Materials in Gas Fluidized Beds with Electrostatic Effects

Mixing Behaviors of Granular Materials in Gas Fluidized Beds with Electrostatic Effects

Experimental Investigation of Electrostatic Charge Generation for Granules

Studies on the effect of electrode plate position and feed temperature on the tribo-electrostatic separation of high ash Indian coking coal

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