The filtration basket has a fabricated/welded or cast design and a filtration basket with a cylindrical shell and filtrate bores through which the filtrate is spun out into the filtrate housing after passing through the filter medium.
Rotary siphon basket
Unlike the conventional perforated basket, the rotary siphon basket has a solid cylindrical shell with filtrate bores arranged radially at the rear end of the basket, where they are connected to a siphon-shaped chamber. Once it has penetrated the filter cake and the filter medium, the filtrate is redirected through axial channels beneath filter medium support segments into the siphon chamber, where a pivoting skimmer pipe extracts it from the centrifuge under positive pressure. The radial distance between the filter medium and the liquid level in the siphon chamber increases the driving force and thus, also the filtration rate.
Residual heel removal
After frequent cycles, the residual heel may have compacted with enough fine solids to make it impermeable, resulting in poor filtration performance. When this occurs, the heel can be regenerated (by backwashing in siphon peeler centrifuges) or removed pneumatically or hydraulically (in peeler centrifuges with filtration baskets).
Pneumatic heel removal
By blowing either compressed air or nitrogen against the heel through special flat-jet nozzles mounted on a pivoting and oscillating manifold inside the basket, the heel cake is broken up into pieces and discharged by the peeling device.
Hydraulic heel removal
Using the feed distributor, a large quantity of rinse liquid is fed to the basket for a short period of time. The resulting shear forces create sufficient turbulence to lift the heel off the filter medium. The rinse liquid with the dispersed heel solids is discharged from the basket by the peeling device. This step requires diverting the liquid to outside the centrifuge away from the normal dry product discharge. The rinse liquid can be recycled to the main process or divided into heel solids and liquid in a separate process step. In both procedures, the heel is removed at low basket speeds to avoid tearing the filter medium. Hydraulic heel removal has the added advantage of simultaneously cleaning the interior of the centrifuge. The most suitable removal procedure will depend upon the specific application.