Bi, Xiaotao T.

Grace, John R.

Moughrabiah, Wajeeh O.

English

Engineering Conferences International

Engineering Conferences InternationalECI Digital ArchivesThe 14th International Conference on Fluidization– From Fundamentals to Products Refereed Proceedings2013Effects of Particle Properties, Temperature andRelative Humidity on Electrostatics in Gas-SolidFluidized BedsWajeeh O. MoughrabiahUniversity of British Columbia, CanadaJohn R. GraceUniversity of British Columbia, CanadaXiaotao T. BiUniversity of British Columbia, CanadaFollow this and additional works at: http://dc.engconfintl.org/fluidization_xivPart of the Chemical Engineering CommonsThis Article is brought to you for free and open access by the Refereed Proceedings at ECI Digital Archives. It has been accepted for inclusion in The14th International Conference on Fluidization – From Fundamentals to Products by an authorized administrator of ECI Digital Archives. For moreinformation, please contact franco@bepress.com.Recommended CitationWajeeh O. Moughrabiah, John R. Grace, and Xiaotao T. Bi, "Effects of Particle Properties, Temperature and Relative Humidity onElectrostatics in Gas-Solid Fluidized Beds" in "The 14th International Conference on Fluidization – From Fundamentals to Products",J.A.M. Kuipers, Eindhoven University of Technology R.F. Mudde, Delft University of Technology J.R. van Ommen, Delft Universityof Technology N.G. Deen, Eindhoven University of Technology Eds, ECI Symposium Series, (2013). http://dc.engconfintl.org/fluidization_xiv/9Effects of Particle Properties, Temperature and Relative Humidity  on Electrostatics in Gas-Solid Fluidized Beds  Wajeeh O. Moughrabiah*, John R. Grace, Xiaotao T. Bi  Fluidization Research Center Department of Chemical and Biological Engineering, University of British Columbia 2360 East Mall, Vancouver, Canada, V6T 1Z3     Abstract  Electrostatic charges in polyolefin fluidized bed reactors are unavoidable. Minor reduction in electrostatics could substantially improve operation and reduce downtime. In this study the influences of particle size, density, shape, temperature and relative humidity were investigated. Eight collision probes at different levels in the bed measured electrostatics. Charges were higher in beds of 45 µm glass bead particles than 250-850 µm beads, probably due to an increase in bubble splitting, complexity of emulsion flow patterns, increased particle-particle and particle-wall contact surface areas and domination of other interparticle forces such as van der Waals forces. Addition of fine glass beads (up to 5 wt%) to a bed containing 650 µm particles decreased electrostatics. As the amount of fine glass beads increased beyond 10 wt%, electrical charges increased.  When the density of polyethylene particles increased, electrostatics increased. Particle shape played a significant role in determining particle charging mechanisms and consistency of the degree of electrification in the bed. Non-spherical particles with uneven surfaces produced inconsistent electrostatics compared to beds of closely spherical particles, probably due to different charging mechanisms. Temperature played a significant role in determining the charge polarity. At higher temperatures (up to 90°C) the polarity in the bed was opposite to that at low temperatures (<50°C). The bed exhibited smoother fluidization at higher temperatures (up to 90°C).  Increasing the relative humidity of the fluidizing air to 30% reduced electrostatic charging in the bed, probably due to increasing surface conductivity, thereby enhancing charge dissipation.  

Effects of Particle Properties, Temperature and Relative Humidity  on Electrostatics in Gas-Solid Fluidized Beds

https://dc.engconfintl.org/cgi/viewcontent.cgi?article=1127&amp;context=fluidization_xiv

Effects of Particle Properties, Temperature and Relative Humidity on Electrostatics in Gas-Solid Fluidized Beds

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