Charge measurement of dust particles in motion

Abstract

The charging of dusts or powders formed in a discontinuous flux in air is measured with a novel non-contactive method. A special ring probe was designed to measure the resultant electric charge of dust particles passing through the probe without disturbing the flow. The scope of the investigations was to verify the method proposed and to examine the influence of mass, equilibrium moisture content and velocity of motion on the electrification of PVC dusts. Experiments were carried out to study the generation of charge in the initial stage of flux formation. A mathematical model was derived to describe the response of the measuring system to the flowing resultant charge and its velocity. After the measuring system had been calibrated the empirical equation was obtained. The resultant charge (qr) and the initial rate of charge accumulation in the flux are found to be strongly dependent on the velocity of the air carrier, which causes that the dust particles are torn off from the metal surface of the feeder. The validity of the adopted measuring procedure is proved by experiments. The results obtained in terms of the mathematical model are consistent with the experimental data.