Numerical study of the effects of cartridge shape on the reverse pulsed flow cleaning of pleated cartridge filters

Abstract

Patchy cleaning is one of the principal factors resulting in the reduction of the efficiency and quality of reverse pulse-jet cleaning as well as the service lifetime of filtration units. To resolve the above issues, a new pleated cartridge shape was introduced in this study to improve the cleaning efficiency and quality of pleated filter cartridges. To calculate the transient flow and pressure fields for a simple filtration system with one filter cartridge in the reverse pulse-jet cleaning process, an unsteady computational fluid dynamics model was developed via the commercial computational fluid dynamics software of ANSYS CFX. The transient static pressure fields for filter cartridges under four different pleated cartridge shapes were studied. The conventional cylindrical cartridge was selected as the base-model of filter cartridge and contrasted with other three cartridge shapes. It was found that the convergent–divergent cartridge was able to effectively improve the cleaning performance without the increase of tank pressure. Different pleated cartridge shapes are expected to be able to redistribute the pressure drop across the porous media along the filter height and to improve the flow behavior after pulsing gas releasing from the nozzle. For convergent–divergent cartridge shape, the peak pressure on the inner surface of porous media has an obvious increase and the peak pressure arriving time is earlier than other cases. It shows that the reverse flow has much more competence to remove the dust powder or cake from the porous media. At the same time, the area-averaged pressure drop at the bottom section of the filter has an increase of 50% under the cartridge with a convergent–divergent shape compared to that with a cylindrical shape. It is considered to enhance the cleaning mechanical stress at the bottom section of the filter cartridge. The better cleaning performance was observed in the medium, with 150% increase compared to that with a cylindrical shape. Furthermore, the cleaning performance gets improved because the value enhances on the top section. The redistribution of pressure drop observed is mainly because the special geometric construction of pleated cartridges compresses the flow on the medium and produce higher pressure drop there. Further studies indicate that the improved cleaning performance was observable under the consideration of the tank pressure reduction and variation of media permeability during each cleaning phase, and the change of pleated cartridge shapes can also improve the cleaning performance when combined with other improvement methods.