Keywords: ESP, electrostatic precipitators, re-entrainment, diesel exhaust gas, particle depositon, ion concentration, gas neutralisation, tunnel decontamination, downstream walls
Suppression of particle deposition onto downstream wall in an AC Electrostatic Precipitator with neutralisation
Electrostatic Precipitators (ESPs) are used to decontaminate polluted environment around the tunnels. A conventional ESP has high collection efficiency but still has a problem in that its downstream walls are polluted due to particle deposition. The experiments carried out in this study have focused on how the particle deposition can be prevented by neutralising the gases. The collection efficiency as a function of particle diameter and the amount of deposited particles on the wall were studied on three types of the ESP: the universal ESP under DC operating mode (DCESP), the ESP under AC operating mode (ACESP) and the ACESP with gas-neutralising equipment (ACESP with neutralisation). Electrostatic field intensity and ion concentration were also measured to understand the state of neutralising the gases. The ACESP, an invention of the authors, prevents particle re-entrainment. The ACESP with neutralisation, which not only prevents the particle re-entrainment but also decreases the charge amount of the downstream gases, was most effective in decreasing the amount of deposited particles.