Testing a new device for suppressing electrostatic charges on polymer granules

Abstract Large discharges along the surface of the silo heap of polyethylene granules were reproducibly generated during filling of a 3 m diameter earthed metallic silo. The specific charge acquired by the granules during pneumatic transport was of the order of 2 μC kg −1 and the mass flow rate of the granules was approximately 1 kg s −1 (3.6 metric tons h −1 ). The rate of discharges depends on the height of the heap and varied from 4 to 8 discharges min −1 . By operating a three nozzle injector of bipolar ions in a carefully optimized arrangement at a short distance from the granules' entry port, all discharges were immediately suppressed.