Principle of the Separation System
- The decanter is used for the separation of two or more phases of different specific gravity, in particular for the clarifying of liquids in which suspended solids are present.
- The separation of solids and liquids takes place within a cylindrical/conical rotating bowl, upon the periphery of which the heavier solid phase collects and is continually removed by the internal conveyor.
- A polyelectrolyte, suitably chosen for its type and specific characteristics, may be added to the product being fed to the machine in order to improve the solid liquid separation.
- The polyelectrolyte favours the aggregation and thus the easier capture of the solid particles. A polyelectrolyte is not always compatible with products being processed. It is generally used in purification processes for the drying of sludge, but not in intermediate product conversion processes, and even less in the processing of foodstuffs.
Principle of Operation
- A decanter centrifuge works according to the same physical rules as a settling tank but with a more than 2500 times faster separation velocity than in the earth gravity field; the requirement for this is that the solid density of the incoming suspension has to be higher than the liquid density.
- The separation of solids takes place in the cylindrical part of the bowl where they collect at the periphery. An internal conveyor moves the solids out of the liquid pond via the conical part of the bowl. At the end of the conical part. the dewatered solids are discharged through ports out of the bowl. Due to the screw conveyor forced discharge. it is possible to handle highly concentrated suspensions with a particles size range of between 10 and 500 micron.
- At the opposite cylindrical end of the bowl. the clarified liquid leaves the rotating part of the machine flowing over adjustable weir-plates.
- The conveying velocity. the so-called “differential speed” between bowl and conveyor is generated using an planetary gearbox.
- Various options are available to adapt the machine to the special requirements of the particular process. e.g. separation of two liquid phases, highly resistant wear protection, highgrade stainless steel, automatic differential speed control via secondary motor –the Roto- Variator- and frequency converter.