Investigation of electrostatic charge distribution within the reactor wall fouling and bulk regions of a gas–solid fluidized bed

Salama, Fawzi; Sowinski, Andrew; Atieh, Khaled; Mehrani, Poupak

doi:10.1016/j.elstat.2012.11.002

Cited by 47 publications

(32 citation statements)

References 28 publications

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“…That said, attractive forces not accounted in this study could explain formation of motionless particle layers on the wall. A plausible explanation for such a structure could be a bipolar charge distribution (Salama et al 2013;Song & Mehrani 2017), which in single-component systems is associated with different charging tendencies of differently sized particles (Cartwright et al 1985;Mehrani, Bi & Grace 2005;Forward, Lacks & Sankaran 2008). Even with tightly monodisperse particles, the effective work function could be somewhat different for the various particles (as opposed to the same value assumed in our simulations), for example, due to the differences in surface heterogeneities.…”

Section: Discussionmentioning

confidence: 62%

“…Mehrani and co-workers (Salama et al 2013;Song & Mehrani 2017) have suggested that the particle sheet on the wall would consist of alternating layers of bipolar particles that attract each other. While this mechanism is feasible, it requires a fairly wide charge distribution.…”

mentioning

confidence: 99%

“…In gas-solid and granular flows, triboelectric charging may cause particle agglomeration (LaMarche et al 2010;Lee et al 2015); affects particle entrainment rate (Fotovat et al 2017a;Fotovat, Grace & Bi 2017c;Yang et al 2017); affects bubble size and shape in bubbling fluidized beds (Jalalinejad, Bi & Grace 2012;Rokkam et al 2013); and leads to adhesion of particles to the walls (Hendrickson 2006;Sowinski, Mayne & Mehrani 2012;Salama et al 2013;Song & Mehrani 2017). For instance, this may result in wall sheeting seen in polymerization reactors that hinders the reactor performance (Hendrickson 2006).…”

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confidence: 99%

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Experimental and numerical study of wall layer development in a tribocharged fluidized bed

Sippola

Kolehmainen

Özel³

et al. 2018

J. Fluid Mech.

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The effects of triboelectricity in a small-scale fluidized bed of polyethylene particles were investigated by imaging the particle layer in the vicinity of the column wall and by measuring the pressure drop across the bed. The average charge on the particles was altered by changing the relative humidity of the gas. A triboelectric charging model coupled with a computational fluid dynamics-discrete element method (CFD-DEM) model was utilized to simulate gas-particle flow in the bed. The electrostatic forces were evaluated based on a particle-particle particle-mesh method, accounting for the surface charge on the insulating walls. It was found that simulations with fixed and uniform charge distribution among the particles capture remarkably well both the agglomeration of the particles on the wall and the associated decrease in the pressure drop across the bed. With a dynamic tribocharging model, the charging rate had to be accelerated to render the computations affordable. Such simulations with an artificial acceleration significantly over-predict charge segregation and the wall becomes rapidly sheeted with a single layer of strongly charged particles.

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Section: Discussionmentioning

confidence: 62%

mentioning

confidence: 99%

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confidence: 99%

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Experimental and numerical study of wall layer development in a tribocharged fluidized bed

Sippola

Kolehmainen

Özel³

et al. 2018

J. Fluid Mech.

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“…The negatively charged particles were inclined to move toward the wall due to the electrostatic attractive forces and thus caused wall sheeting . Figure further shows the photos of wall sheeting in the fluidized bed after injection of LAA.…”

Section: Resultsmentioning

confidence: 99%

Experimental investigation of electrostatic effect on bubble behaviors in gas‐solid fluidized bed

et al. 2015

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Electrostatics and hydrodynamics in the fluidized bed are mutually affected, and excess accumulation of electrostatic charges has a severe impact on hydrodynamics. However, there is a serious lack of experimental investigation of electrostatic effect on hydrodynamics. This work provides a first insight into the electrostatic effects on bubble behaviors experimentally by injecting a trace of liquid antistatic agents (LAA) into a fluidized bed. Different amounts of LAA (0–50 ppm) were injected to make the electrostatic charges vary in a wide range and the bubble behaviors were investigated simultaneously. Results showed that the charges on particles decreased with increasing amount of LAA, which resulted in larger bubble sizes, stronger fluctuations of dynamic bed height, and less wall sheeting, respectively. The maximum reduction ratio of bubble sizes due to electrostatic effect was 21%. When particles were charged, the bubble sizes were significantly smaller than those estimated from the classical correlation. This discrepancy was attributed to the neglect of electrostatic effect in classical correlation. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1160–1171, 2015

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“…It will be shown that when particle charge is allowed to evolve through tribocharging, particles carry a distribution of charges, consistent with the experiments of Lee et al 42 A bipolar distribution of charges arises in some cases, consistent with previous experiments. 1,30,42,43 This bipolar distribution arises in part due to long-range electrostatic forces and creates changes in hydrodynamics which cannot be seen in simulations using monopolar fixed charges.…”

Section: Introductionmentioning

confidence: 99%

Triboelectric charging of monodisperse particles in fluidized beds

et al. 2016

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To investigate the interplay between particle charging and hydrodynamics in fluidized beds, models for triboelectric charging and electrostatic forces were built into a computational fluid dynamics‐discrete element method model. Charge transfer was governed by the difference in effective work function between contacting materials as well as the electric field at the point of contact. Monodisperse particles were fluidized with an effective work function difference between the particles and the conducting walls. For smaller work function differences, hydrodynamics were not changed significantly as compared with an uncharged case. In these simulations, the average charge saturated at a value much lower than the value anticipated based on the work function difference, and a unimodal distribution of charges was observed. For larger work function differences, particles stuck to walls and bed height oscillations due to slugging were less pronounced. For these cases, a bimodal distribution of charges emerged due to effects from strong electric fields. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1872–1891, 2017

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Investigation of electrostatic charge distribution within the reactor wall fouling and bulk regions of a gas–solid fluidized bed

Cited by 47 publications

References 28 publications

Experimental and numerical study of wall layer development in a tribocharged fluidized bed

Experimental and numerical study of wall layer development in a tribocharged fluidized bed

Experimental investigation of electrostatic effect on bubble behaviors in gas‐solid fluidized bed

Triboelectric charging of monodisperse particles in fluidized beds

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