Electrostatics of the Granular Flow in a Vertical Pneumatic Conveying System

The phenomenon of electrostatic charge generation in a pneumatic conveying system was studied. The main parameters used for quantitative characterization of the phenomenon included induced current, particle charge density and equivalent current of the charged granular flow. These were measured using a Digital Electrometer, Faraday Cage and Modular Parametric Current Transformer (MPCT) respectively. Three different flow patterns corresponding to the different electrostatic effects within the pneumatic conveying system were observed and these were classified as the disperse flow, half-ring flow and ring flow patterns. It was found that the induced current, particle charge density and equivalent current increased with decreasing flow rates. Electrostatic effects generally become stronger with time and this may lead to clustering behavior occurring even in the disperse flow regime.