1:30 PM - 1:45 PM
[16p-Z13-1] Electrostatic Discharges from Metal Protrusion during Powder loading
Keywords:electrostatic discharges, electrostatic charges, powder
In this study, the electrostatic discharges from a metal protrusion existed inside a conical-cylindrical silo during continuous loading of polypropylene powders (approximately 3 mm) was experimentally investigated. A pilot-scale silo connected to a pneumatic powder transport facility was used while all parts were electrically grounded. The metal protrusion used in this study had a diameter of 4 cm. The silo was continuously loaded with PP powders at a mass flow rate of 0.68 kg/s to a total mass of approximately 800 kg. An image-intensifier unit was used to observe the electrostatic discharges generated from the metal protrusion and a current probe attached to an oscilloscope was used to measure the discharge amount (Q [nC]).
As for the results, a multiplicity of small electrostatic discharges (brush discharges) from protrusion were clearly observed. First electrostatic discharges during the PP powder loading were developed at 391 s mark, when approximately 270 kg of the powder was loaded. In addition, a difference in the electrostatic discharges before and after the protrusion was embedded in the accumulated powder was observed. That is to say, the electrostatic discharges after the metal protrusion was embedded in the accumulated powder was stronger than that when it was not embedded. As well, the Q after immersion of the metal protrusion in the accumulated powder was several times larger than that when the protrusion was out. Furthermore, strong broad bulk surface discharges clearly appeared after the protrusion was fully immersed in the powder.
As for the results, a multiplicity of small electrostatic discharges (brush discharges) from protrusion were clearly observed. First electrostatic discharges during the PP powder loading were developed at 391 s mark, when approximately 270 kg of the powder was loaded. In addition, a difference in the electrostatic discharges before and after the protrusion was embedded in the accumulated powder was observed. That is to say, the electrostatic discharges after the metal protrusion was embedded in the accumulated powder was stronger than that when it was not embedded. As well, the Q after immersion of the metal protrusion in the accumulated powder was several times larger than that when the protrusion was out. Furthermore, strong broad bulk surface discharges clearly appeared after the protrusion was fully immersed in the powder.