Working Principle of a Bag-Pull Centrifuge
A bag-pull centrifuge is called such because it adds a bag-pulling action compared to a regular automatic unloading centrifuge. An additional bag-pulling cylinder is installed above the discharge port. After the scraper scrapes the material, the remaining filter cake is shaken off by the bag and enters the discharge port. Unlike regular automatic unloading centrifuges, which require manual cleaning of the filter bags after about 8 hours of operation, this type of centrifuge offers a higher degree of automation and allows for continuous production.
The configuration of a bag-pull centrifuge is almost identical to that of a regular unloading centrifuge, except for the addition of the bag-pulling device. The complete working process of a bag-pull centrifuge is as follows:
Feeding and Separation: Medium-speed material distribution, where the material is evenly distributed onto the drum wall by a rotating inclined disc distributor.
Washing and Spin-drying (Optional): When the material level detector detects that the material has reached the set position, feeding stops, and the rotation speed is increased to spin-dry the material. If the purity of the solid product is required, washing liquid can be added at this step before spin-drying.
Scraper Discharge: After spin-drying, the drum speed is reduced to low speed. The scraper extends into the rotating basket and scrapes off most of the filter layer, which falls to the outlet due to gravity. However, a very thin residual layer (about 20mm) must remain between the scraper and the filter cloth to prevent the scraper from directly damaging the filter cloth.
Pull-bag cleaning of residual filter cake: After the scraper discharges the material, a pneumatic or linkage mechanism drives the bottom of the filter bag to move up and down repeatedly within the rotating drum. This "lifting and shaking" action removes the thin layer of stubborn filter cake remaining on the surface of the filter cloth.
From the working principle of the pull-bag centrifuge, it can be seen that the pull-bag centrifuge has a higher degree of automation. The entire process, from feeding, primary filtration, washing, fine filtration, to unloading, is automated, achieving unmanned operation. It can also remove residual filter cake, avoiding cross-contamination between different batches of products, complying with GMP standards. Furthermore, timely removal of the filter cake layer can unclog the filter cloth pores, preventing clogging and reduced filter cloth efficiency.
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