The effects of granular velocity and shape factors on the generation of polymer-metal electrostatic charge

Electrostatic charge has been observed in many gas-solid two-phase processing systems, which may cause serious industry problems, such as particle clustering, blockage and explosion hazards. However, the fundamental mechanism of electrostatic charge generation has not yet been well studied. The effects of granule velocity, granular shape factors such as front-facing angle, length-ratio and sliding area, as well as charge saturation on electrostatic charge generation were studied in this work, using polyvinyl chloride (PVC) granules (diameter 1.1-4.1 mm, with triangular or trapezoidal sliding faces). The mechanism of electron transfer between polymer and metal was analyzed. It was found that the charge generation on granules is strongly dependent on the sliding velocity. The amount of electrostatic charge generated on a granule increases with the decreasing velocity. Longer contact time is considered to account for this phenomenon. For both triangular and trapezoidal granules, the electrostatic charge generated tends to become saturated after sliding certain times, where accurate charge saturation fitting has been achieved. (C) 2016 Elsevier B.V. All rights reserved.