Electrostatic charging behaviour of dielectric particles in a pressurized gas-solid fluidized bed

The charging behaviour of insulating particles in pressurized fluidized beds was investigated by fluidizing five polyethylene resins in a column of 150 mm inner diameter and 2.0 m height. Seven collision ball probes at different levels and radial positions monitored the electrostatic charge generation in the bed. The influences of operating pressure and superficial gas velocity on the degree of electrification were studied. For each polyethylene resin, the electrostatic charges of the particles in the upper part of the bed gained a polarity which differed from the particles in the lower part of the bed due to bipolar charging and particle segregation. The hydrodynamics in the fluidized bed significantly influenced the particle electrification. Due to increased bubble size and rise velocity, electrostatic charge generation was enhanced as the superficial gas velocity increased. However, it was difficult to predict the influence of elevated pressure on the charging behaviour of each resin as a result of the complex impacts of pressurization on the hydrodynamics and electrification. (C) 2010 Elsevier B.V. All rights reserved.