Local occurrence of back corona at the dust layer of electrostatic precipitators

This paper deals with investigations of back corona behaviour at the collecting electrodes of electrostatic precipitators. Experimental investigations with high-resistivity dust have been performed in a laboratory scale electrostatic precipitator. High dust resistivities in combination with a high electric field are responsible for the occurrence of back corona which is the cause for a dramatic decrease in the efficiency of an electrostatic precipitator. The local occurrence strongly depends on dust layer thickness and porosity which is strongly influenced by forces of the electrohydrodynamic field. The corresponding increase of the electric current density was monitored and compared for different geometric parameters and electric operation settings. The present paper presents impressive observations of back-corona discharges. The results of these investigations underline the existence of different types of back corona. Moreover, the experiments show a correlation between the quality of the dust layer and the occurrence of back corona.