PARTICLE PRECHARGING AND FABRIC FILTRATION - EXPERIMENTAL RESULTS OF A CORONA PRECHARGER

A corona precharger has been installed in front of a pilot-sized, puls e-jet cassette filter. Experiments under ambient conditions with re-di spersed fly ash as well as experiments at higher gas temperatures (up to 130 degrees C) have been performed. The net electrostatic charge on the particles was measured directly behind the precharger. The effect of the corona pre-charge, the triboelectric charge and discharging th e particles on the filtration behaviour of the fly ashes was evaluated . The pressure loss of the dust cake as well as the cycle time between back-pulse cleaning was improved under certain conditions. Collection efficiency has been enhanced by charging of the fly ash particles. It has been observed that the beneficial effect of the particle precharg ing depends strongly on the gas velocity in the system, the dust conce ntration and the tribocharge on the fly ash. Back-corona effects in th e precharger unit had been detected. It was tried to suppress these ne gative effects on performance by intermittent energization of the high -voltage power supply connected to the corona precharger. The results of these experiments will be presented and discussed.