Applications of electrostatic probes in fluidized beds

The electrostatic charge in a fluidized bed can be applied to provide local information on the bed hydrodynamics. Electrostatic probes can withstand adverse conditions that would be an issue for other measurement probes, such as high temperatures (limited by metal), high velocities (e.g. 2 m/s), high bed densities (1500 kg/m3), and large-scale equipment. The objective of this study was to investigate various applications of electrostatic probes in fluidized beds. Results obtained with an array of 45 probes arranged in 5 rows provided the local bubble gas flux and bubble velocity. They could also be used to detect any slugging. When liquid was sprayed into the gas-fluidized bed, the electrostatic probes could provide the penetration of the gas-liquid spray jet, detect bogging and measure the free moisture, i.e. the amount of liquid that was not trapped within wet agglomerates. The electrostatic probes measurements were validated with alternate measurement methods. [Display omitted] •Electrostatic probe measurements with dry bed provide: Gas bubble flow profile, Bogging detection.•Electrostatic probe measurements with wet bed provide: Jet penetration, Liquid distribution.•Cross-correlation between the signals from several electrostatic probe provides: Slugging detection, Bubble velocity.