The effects of a corona precharger on the performance of a fabric filter were studied experimentally in the air with controlled humidity. Test dusts, fine calcium carbonate and fly ash, were precharged and then introduced to a test fabric. The test fabrics were felt, spun staple and filament woven fabrics.
When charged dust is collected on a test fabric at low filtration velocity and low relative humidity, a rugged surface often appears on the charged dust layer, and pressure loss across the loaded test fabric is reduced. This electrostatic effect on pressure loss occurs not only for felt fabric but also for spun staple woven fabric, but does not appear for polyester (Tetron) and glass filament woven fabrics, because of pin-hole formation.
On the other hand, the collection efficiency of a fabric filter can always be improved by using a corona precharger. The collection efficiency increases with the charge-to-mass ratio of dust. Even if pin-holes are formed during the filtration, the collection efficiency can be improved using a corona precharger, without substituting a higher-performance fabric.