Powder Technology, Vol.340, 543-552, 2018
Balance and stability between particle collection and re-entrainment inawide temperature-range electrostatic precipitator
In an electrostatic precipitator, particles migrate to the collecting plates through electrostatic force. Simultaneously, the effect of gravity and hydrodynamic drag force will cause these particles to vacate the plates. Emission concentration and removal efficiency gradually stabilize after the particles pass through multiple electric fields, and this stability value determines the high limit of electrostatic precipitation capacity. In this study, the balance between particle electrostatic trapping and air re-entrainment was investigated through a closed-loop electrostatic precipitator system, and the behavior of the particles deposited into the collecting plates was qualitatively analyzed. The particle emission concentration was reduced significantly when residence time was within 40 s. The particle concentration reached its limit and remained relatively stable after remaining stable for 100 s in the electric field. The applied voltage, velocity of flow, and temperature are the influencing factors considered in this study, here it was found that the decreased flow velocity, temperature and rising voltage were benefiting to particles removal efficiency. The ultimate emission concentration gradually decreased from 13.14 mg/m(3) to 7.19 mg/m(3) while the velocity of the flow decreased from 0376 m/s to 0240 m/s at the temperature of 700 K. The ultimate emission concentration gradually increased from 6.24 mg/m(3) to 1.79 mg/m(3) while the temperature decreased from 800 K to 400 K when the flue gas velocity was 0376 m/s, and the applied voltage was at its maximum which can be used at the corresponding temperature. The ultimate emission concentration gradually decreased from 19.5 mg/m(3) to 6.0 mg/m(3) when the flue gas temperature was 400 K, and the velocity of the flow was 0376 m/s, with the increase in voltage from 14.9 kV to 32.5 kV. In addition, particles of different size segments and specific resistances exhibited various characteristics in this study because the electrostatic and van der Waals forces were significantly affected by the particle size. (C) 2018 Elsevier B.V. All rights reserved.