BACK-CORONA MODEL FOR PREDICTION OF ESP EFFICIENCY AND VOLTAGE-CURRENT CHARACTERISTICS.

The back-corona discharge is formed by a series of micro -discharges in the air spaces between the partcles of the dust layer deposited on the collecting plates. It starts when the particle resistivity is quite high: it changes the voltage-current characteristics of the electrostatic precipitator and significantly lowers its efficiency. In the present work, the variation of the voltage-current characteristics, depending on resistivity and particle layer thickness, has been successfully reproduced by a simple electrical circuit model of the dust layer, including a back -corona current generator and the voltage drop across the particle layer. The model also includes an estimation of the variation of the captation efficiency: as back corona lowers the ion space charge, the computation of the back-corona current allows to evaluate the variation of the particle charging rate and therefore of their migration velocity.