Oilseeds Continuous Pressing: Theoretical and Experimental Analyses
Bogaert L.1,2, Mhemdi H.1, Carre P.2, Fine F.3, Quinsac A.3, Vorobiev E.1
1UTC/ESCOM, Compiègne/F, 2OLEAD, Pessac/F, 3Terres Inovia, Pessac/F 

Continuous screw pressing is widely applied for mechanical extraction of oil from oilseeds. Despite significant recent advances in the field of press design and automation, the prediction of performance based on theoretical approaches remains difficult. This work is devoted to better understand, characterize and model the solid/liquid behavior in a screw press by comparing experimental and theoretical approaches. 
For this purpose, a pilot (0-40 kg/h) screw press (Reinartz, Germany) was instrumented and divided into five sections. Winter rapeseed seeds were used for investigation. For each section, the pressure, the temperature and the oil flow rate were measured and recorded. Additionally, samples of press cake were taken in the different sections and analyzed (porosity, residual oil content). 
The experimental results showed the presence of successive sections of compression and mixing. An agreement was found between oil flow rates and pressure values in the compression sections. The total oil yield increased with lower rotation speed and the maximal oil yield was approximately 90 %. The residence time distribution in the press was studied and showed an important oil recirculation and axial dispersion of mass flow through the screw press. These phenomena will be taken into account for oil expression kinetics modeling.