Annular-slit nozzles for reverse flow cleaning of pleated filter cartridges

Annular-slit nozzles were proposed to reduce the patchy cleaning often encountered in the reserve flow process for regenerating filter media in industrial filtration systems. In this study we investigated the effect of annular-slit nozzles on the efficiency and quality of reverse flow cleaning. A 3-D transient numerical model was developed to model the flow and pressure fields in a simple filtration system having a single pleated filter cartridge. The cleaning performance of three different annular-slit nozzles and paired round nozzles (having the same opening area as that of associated annular one) were analyzed. Compared with paired round nozzles, annular-slit nozzles have favorable effect on the local cleaning efficiency of pleated filter cartridges by significant increasing of local static pressure drop, especially in the upper region of pleated filter cartridges. The uniformity of pressure distribution along the cartridge height is also improved, resulting in the less probability of filter media damage by local mechanical stress developed during reverse flow cleaning when increasing the tank pressure. More, the better cleaning quality of reverse flow cleaning is expected because of the induced gas flow passing through the inner tube of an annular-slit nozzle when the air jetting was initiated from the nozzles. The benefit of applying annular-slit nozzles in the reverse flow cleaning was also observed in the cases taking into the consideration of the dust cake release from the cartridge filter surfaces.