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Candle Filtration
CANDLE FILTRATION
For the most efficient possible filtration of spinbath, acid water and backwash bath.
Features
- High filtration quality
- Fully automated with nearly no manpower requirements
- Low maintenance cost
In Detail
FILTRATION
During filtration, which takes place in a pressure vessel, the spinbath is pressed from outside through the filter medium, on which the solids form a uniform cake. The filtrate leaves the filter through the registers which are built into the upper portion of the vessel. To obtain a sufficient filtration time all the time a small quantity of filteraid has to be added into the unfiltered stream before the candle filter. This is done by a small dosing pump.
According to the thickness of the cake the pressure difference increases. After reaching either the maximum pressure difference or the maximum cake thickness the filtration has to be stopped and a regeneration program starts.
CAKE DISCHARGE
After filtration is completed the filter cake can be discharged as dry cake or slurry. Therefore pressure air is used to dry the filter cake and/or to blow back through the candles and throw off the filteraid and dirt.
Discharging the waste as dry cake means manual handling of the filter cake, no waste water generation, but a requirement for high pressure drying air (air pressure approx. 4 bar); a discharge as slurry results in a lower pressure air demand (no drying - an air pressure of only 2 bar is necessary) and means flushing the slurry to the waste water treatment plant.
CLEANING THE FILTER CLOTH
First the filter is filled up with hot water and than the filter cloth is cleaned by pulsed blow-back with pressure air. This action is repeated several times. From time to time a cleaning solution is used.
PRECOATING
First the filteraid, necessary for the filtration, is mixed with filtered backwash bath in a separate tank in order to get a homogenous suspension. This mixture then circulates through the filter back to the tank for filteraid by means of a small circulation pump, until the filteraid coating of the filter candles is complete (precoating layer of approx. 2 mm).
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