Design features and benefits
Sigma decanter centrifuges feature a special design optimized for two-phase operation. Particular features include:
- Fully protected feed zone, benefiting from a new design
- Special conveyor design to improve solids transportation and maximize oil recovery
- Special flight for oil migration to the liquid outlet, designed to help optimize yield and oil clarification by avoiding turbulence
- 360° solids discharge outlet made of tungsten carbide, for exceptional protection against wear
- Tungsten carbide tiles on conveyor, for special wear protection that significantly reduces maintenance costs
- Compact design with small footprint
Electronic control of the conveyor speed (differential speed) means you can adjust the retention time and set it to make sure of maximum oil recovery. A variable frequency drive (VFD) directly connected to the exclusive Alfa Laval direct drive gearbox provides you with electronic control of differential speed. This setup brings you the benefits of minimum power consumption as well as reduced heating of the oil.
Alfa Laval Sigma decanter centrifuges also feature an electronic overload protection system.
High-quality stainless steel is used throughout. The casing is hinged for easy opening, maintenance and cleaning.
Sigma olive oil decanter centrifuge operating principles
The Sigma olive oil decanter centrifuge design makes sure the incoming paste is effectively separated into oil and wet solids.
The olive paste is fed into the bowl of the unit through a stationary inlet tube, and is then smoothly accelerated by an inlet rotor. Separation takes place in a horizontal cylindrical bowl equipped with a screw conveyor. Centrifugal force makes the oil accumulate at the liquid surface, while the solids settle on the inner wall of the bowl, surrounded by the water separated out of the feed stream.
The conveyor rotates at a slightly different speed than the bowl and moves the solids to the discharge ports in the conical end. Olive oil extraction takes place along the entire length of the cylindrical part of the bowl. The oil is returned to the large end for discharge, and then passes into collecting tanks via a filter.