The FUNDA filter operates one batch at a time to remove solids from liquids. When the batch is complete the filter nest briefly spins at high speed to sling off the cake that was collected on the filter plates. The name FUNDA is the latin word for: to sling.
The Type A FUNDA Filter is designed for wet cake discharge and consists of four main parts; the vessel, the head, the filter nest and the filter drive.
Cake Discharge
Once the filter is empty, the filter nest briefly spins at high speed to sling off the cake. The cake falls to the bottom of the vessel where a valve opens to allow the cake to drop into a receptacle. The Type A FUNDA filter features a wiper blade to aid the removal of wet cake discharge. The wiper blade is attached to the bottom of the filter nest and pushes the cake to the outlet. Discharging the cake while still wet reduces the overall time between batches.
Filter Vessel
The largest part of the FUNDA filter is the vessel. It is cylindrical in form with a dished bottom. The head, which is removable, closes the top of the vessel and supports the filter nest and the drive unit. The filter nest is an assembly of horizontal filter plates stacked on a vertical, rotatable hollow shaft. There are upper and lower bearings and seals for the filter shaft. On the Type A FUNDA filter the lower bearing and seal can be serviced without removing the filter nest.
Filter Nest & Filter Motor
Each filter plate assembly consists of a filter plate, a support screen, a filter screen and an outer clamp ring. There is also a passage ring and an inner clamp ring. The inner and outer clamp rings hold the filter screen in place while the support screen and the passage ring are trapped between the filter screen and the filter plate. The slightly dished form of the filter plate assures complete drainage of the filtered liquid. The filter drive can be either electric or hydraulic. The hydraulic drive is directly coupled to the filter shaft while the electric drive employs a reducer. When the electric drive motor is mounted vertically above the filter shaft, a gear reducer is installed. The electric drive option uses a programma- ble VFD speed controller.
Filtration
During operation the unfiltered liquid is pumped into the vessel and flows around the stationary filter nest. When the vessel is full, the pressure in the vessel begins to rise. This pressure forces the unfiltered liquid through the filter screens. The solids are left on the filter plates and the filtered liquid flows into the hollow shaft to drain out through the filtrate outlet which exits through the bottom of the vessel. The filter nest remains stationary during the slurry filtration.
Heel Filtration
Once the slurry filtration is complete some of the unfiltered liquid remains in the FUNDA filter below the lowest filter plate. This is the heel. In order to capture it, the heel can be drained from the filter vessel and pumped to a nozzle on the top of the Funda filter. The unfiltered liquid is directed by a distribution plate, which is mounted inside the head of the filter, to gently cascade over the filter plates until all of the heel has been filtered. Due to the dished shape of the vessel bottom of the Type A FUNDA filter, less heel is left at the end of each batch than that which is left in the cone of a Type R FUNDA filter.