Comparative experiments to assess the performance of an innovative horizontal centrifuge working in a continuous olive oil plant

Abstract

The performance of an innovative horizontal centrifugal decanter working in a continuous industrial olive oil extraction plant was evaluated. This decanter produces two streams a semi-solid residue (or pulp) formed from the wastewater and soft solids (i.e. without fragments of stone) and a husk rich in rigid solids from pit shells. Considering the phase separation obtained using this machine, and increasing number of restrictive laws on waste disposal, this decanter is of significant interest for use in olive oil extraction. The effects of varying the decanter centrifuge settings are documented and discussed. A correlation between the mass flow rate, water ring levels and conveyor-bowl differential speed with respect to the extracted efficiency, husk fat content and pulp water fat content was evaluated. The decanter studied was found to maintain high values of extraction efficiency between 86.5% and 90.8% for a large range of feed mass flow rates (4075–5820 kg h−1) and for a large range of conveyor-bowl differential speeds (15.5–26.0 rpm). In addition, by appropriately adjusting the ring level of the waste-water output, it was possible to obtain a greater or lesser soft solid content, with a greater or lesser amount of residual oil.