Alfa Laval presents the range of Sigma series decanters designed specifically for the two-phase extraction of olive oil. These units are designed to operate in first or second extraction, also known as regrind. The goal is to optimize oil recovery over the entire flow range and, at the same time, to preserve quality by preventing any temperature increases during the extraction process.
The decanters of the Sigma series are designed to guarantee a low cost extraction of olive oil. These compact and efficient decanters are optimized for use in two-stage olive oil separation processes including clarification, extraction and dehydration. With the introduction of the Sigma 6 and Sigma 8 models, in addition to the existing Sigma 9 and Sigma 10 models, Alfa Laval is now able to meet all market needs, from those of small and medium olive oil producers to those of of large industrial oil mills.
Principles of operation
The design of the Sigma centrifugal decanter ensures that the incoming olive paste is effectively separated into oil and wet pomace. The olive paste enters the decanter drum through a stationary inlet tube and is then slowly accelerated into the rotating feed zone. The separation process takes place inside a horizontal cylindrical drum equipped with a screw conveyor. Centrifugal force causes oil to accumulate on the surface of the liquid, while solids settle on the inner wall of the drum, surrounded by water separated from the feed stream. The auger rotates at a slightly different speed than the drum and conveys the solids to the discharge openings of the conical end. Oil separation takes place over the entire length of the cylindrical part of the drum. The oil flows back to the large end for the drain, then passes into the collecting tanks through a filter.