Experimental Study of the Corona Discharge in a Modified Coaxial Wire-Cylinder Electrostatic Precipitator

Coaxial wire-cylinder electrode arrangements are widely used for the electrostatic precipitation of dust particles contained in flue gases. The aim of this work was to evaluate a new design, which was expected to increase the particle collection efficiency. The collector electrode of the several models under study consisted in a cylinder with alternate small- and large- diameter sections. In a first set of experiments, the current- voltage characteristics of each model were compared to those obtained for a standard wire-cylinder electrode arrangement, at both polarities of the high-voltage supply, and for three values of the inlet gas pressure: 1 bar, 1.7 bar, and 2.5 bar. The particle collection efficiency of the different models was evaluated in a second set of experiments, performed with 2-g samples of starch powder, under various operating conditions. Data analysis revealed that the modified precipitators have a higher efficiency than the standard model. For a given geometry of the electrode arrangement, the efficiency was found to depend on the pressure of the inlet gas. This fact could be explained by examining the results of a third set of experiments: the curves that describe the current density distribution inside the models at various values of the inlet gas pressure. The best collection efficiency was obtained at a gas pressure for which the current density was higher in all the sections of the modified precipitator. These findings could serve in the design of new industrial electrostatic precipitators.