Particle charge neutralization in roll-type electroseparators

Safe and efficient operation of industrial electrostatic separators require a strict control of the residual electric charge of the particles emerging from the process. The present paper analyses the efficiency of charge neutralization accomplished by conveniently located electrodes, energized from a.c. high-voltage supplies of 1250 Hz and 50 Hz. The tests were carried out on a laboratory electrostatic separator, provided with two wire-type corona electrodes connected to a fully-adjustable d.c. high-voltage supply of positive polarity (0...30)kV peak value. A needle-type corona electrode was employed for the neutralization of the charge. The particulate material used throughout the experiments consisted of mm-size PVC granules, issued from chopping of electric wire insulation. With both the 1250 Hz high-voltage supply and the conventional 50 Hz high-voltage transformer, about 80% of the material is removed from the surface of the roll electrode, following charge neutralization. The tests should continue with a variable frequency high-voltage supply, in order to establish an optimum value of this parameter under various operating conditions.