Assessment of the energy and separation efficiency of the decanter centrifuge with regulation capability of oil water ring in the industrial process line using a continuous method.

The third era in olive oil extraction sees a new generation of decanter that give the operator the possibility to chose time by time the type of working: two or three phase shifting from one solution to the other without stopping the machine and even intermediate solutions between two or three phase, making the most suitable adjustments, following olive variety, just as the machine works. A decanter centrifuge was employed during the experimental tests with variable differential speed between bowl and screw conveyor (Dn) and with regulation capability of oil-pulp ring levels. Thus permit to shift from three to two phase, reducing water added and discharging the following by-products: dehydrated husk similar to that of three-phase and recovers a wet pulp that is the between the liquid phase and the solid phase. This paper aims to report the preliminary results of the energy and functional efficiency of the decanter when it works in the industrial scale plant and using a continuous method. The trials were carried out at two different flow rate values; for each flow rate the different variable differential speed between bowl and screw conveyor was varied at 15,50, 17,50 and 19,50. Quality olive, operating speed of the crusher machine and relative feed flow rate of the machine, the malaxing time and the degree of dilution of the paste, as well as the oil-pulp ring level were the same for all the trials. Irrespective of the flow rate and Dn used, the machine tends to stabilize energy consumption in a very short time and values were quite similar to each other. The reductions in flow rate do not involve reductions of energy consumption indeed lead to the increase of absorption per unit mass of product worked. For all thesis studied, no significant changes of the oil recovery efficiency were found, indeed changing the flow rate and the Dn a different distribution of the not extracted oil was found in the pulp and in the husk. To complete the knowledge, a set of trials changing also the oil-pulp ring levels, has been provided for the next olive oil season.