A novel dual-material probe for in situ measurement of particle charge densities in gas

He, C., Bi, X. T., & Grace, J. R. (2015). A novel dual-material probe for in situ measurement of particle charge densities in gas–solid fluidized beds. Particuology, 21, 20-31. https://doi.org/10.1016/j.partic.2014.11.001

A novel dual-material probe for in situ measurement of particle charge densities in gas–solid fluidized beds

Chuan He, Xiaotao T. Bi ^*, John R. Grace

Fluidization Research Centre, Department of Chemical and Biological Engineering, The University of British Columbia, 2360 East Mall, Vancouver V6T 1Z3, BC, Canada

10.1016/j.partic.2014.11.001

Volume 21, August 2015, Pages 20-31

Received 6 May 2014, Revised 20 October 2014, Accepted 13 November 2014, Available online 26 December 2014, Version of Record 6 June 2015.

E-mail: xbi@chbe.ubc.ca

Highlights

• Particle charge density and bubble velocity were measured by a dual-material probe.

• Probe measurements were compared with Faraday cup and video data retrieved from 2D fluidized bed.

• Probe signals and video images were synchronized for calibration of the probe.

• Current peaks are related to particle charge density and bubble rise velocity.

• Differences in signals between the two tips arise mainly from charge transfer.

Abstract

Particle charge density is vitally important for monitoring electrostatic charges and understanding particle charging behavior in fluidized beds. In this paper, a dual-material probe was tested in a gas–solid fluidized bed for measuring the charge density of fluidized particles. The experiments were conducted in a two-dimensional fluidized bed with both single bubble injection and freely bubbling, at various particle charge densities and superficial gas velocities. Uniformly sized glass beads were used to eliminate complicating factors at this early stage of probe development. Peak currents, extracted from dynamic signals, were decoupled to determine charge densities of bed particles, which were found to be qualitatively and quantitatively consistent with charge densities directly measured by Faraday cup from the freely bubbling fluidized bed. The current signals were also decoupled to estimate bubble rise velocities, which were found to be in reasonable agreement with those obtained directly by analyzing video images.

Graphical abstract

Keywords

Electrostatics; Particle charge density; Dual-material collision probe; Signal decoupling; Fluidized bed; Bubble rise velocity

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