Semi Continuous Centrifuge
Principle
- Short cycle batch centrifuges are also known as automatic batch centrifuges.
- Filtration centrifuges are used for filtration. A perforated wall achieves separation by using the difference in densities of solids and liquids.
- A perforated sidewall is present in the bowl. As the liquid phase travels through the wall of the bowl during centrifugation, the solid phase is retained.
- The solid is cut away using blades.
Construction
The following image shows how a semi continuous centrifuge is constructed. An electric motor is powering the horizontal shaft that supports a vertical perforated basket. Through horizontal tubes, feed and wash pipes can be introduced from the open side of the basket. The diaphragm valve is linked by an air supply to a feeler which rides over the feet. Through the feeler, the feed is controlled in thickness. Crystals are discharged out of the basket by means of a hydraulic cylinder attached to an entry chute.
Working
- A rotating perforated basket is inserted through a pipe to the side of the bowl/basket so that the liquid feed is distributed evenly throughout the basket.
- The walls of the trough are perforated, allowing liquid to pass through while solid remains inside the trough.
- Water is used to wash the cake. Through the filtrate outlet, the wash escapes.
- Spinning collects the solids after drying, while outlet collection collects the liquid.
- A feeler in this centrifuge cuts off the air supply to the diaphragm valve after it has reached the desired thickness of 50 to 70 mm, thus cutting off the flow of slurry.
Merits
When solids can be drained from a bowl without stopping, a short-cycle automatic batch centrifuge is used.Demerits
Crystals can break considerably during discharge. It's complicated to construct and it's complicated to operate thanks to many moving parts.
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