Electrostatic elimination of charged particles by DC-type bipolar electrostatic eliminator

The electrostatic eliminator is widely used to prevent silos from explosions caused by the electrostatic discharge of charged particles. However, electrostatic accidents still happen occasionally. This study investigated charge elimination characteristics of the DC-type bipolar electrostatic eliminator under different configurations of the applied voltages, air velocities, and initial charge densities of particles for helping improve the charge elimination efficiency. The results show that the unipolar corona discharge will lead to reverse charging of particles, while the bipolar corona discharge at a suitable configuration can neutralize the charged particles completely. The upper and lower ionizers in the bipolar electrostatic eliminator should be applied with positive and negative voltages, respectively, and the positive voltage should be greater than the negative one. The suitable configuration of the electrostatic eliminator is insensitive to air velocity due to the simultaneous increase of the charging capability of positive and negative corona discharges with increasing the air velocity. This electrostatic eliminator can neutralize the charged particles with a net negative charge even in the presence of positively charged particles in the mixture. Furthermore, the performance of this electrostatic eliminator on a full-scale silo was examined using a light intensifier to observe the electrostatic discharge inside the silo. The proposed electrostatic eliminator was found to be effective in eliminating the electrostatic discharge in the silo.