Numerical calculation model on critical compression ratio of castor bean in cold uniaxial press

Castor is an important kind of industrial oil plant with high oil content of about 50%, high protein content of about 15%, and low moisture content of about 6%. A cold pressing process is required to ensure a low degree of pro-tein denaturation when pressed for castor oil. Castor cake is then extracted by solvent to reduce the residual oil of the meal. Main contents of castor beans, feeding morphology and the operating temperature can affect the pressing effect directly. Critical compression ratio of oilseeds is a key reflection for pressing ability of pre-press. In the process of cold pressing, oilseeds are squeezed and ruptured under the interaction with the barrel by the axial compression and lateral limit. Oils in the cells are gradually squeezed out only leaving the cake inside the cylinder barrel. While oilseeds were compressed by axial pressure to make the cells destroyed, drop of the oil was pressed out from the cell through micro holes and gathered to form a flow where there were much more in the bottom than in the top. After pressing, the pressed cake becomes a kind of consolidated system with semi-solid material saturation. The presence of residual stres-ses caused big friction between barrel and cake, which has a significant effect on low power consumption and mecha-nized separation lines. Using self-made testing apparatus, experimental tests on castor oil rate were carried out in dif-ferent pressing pressure and velocities, and the pressure holding time. Based on the principle that oil production value was equal to energy consumption value, the relationship model between critical compression ratio and residual oil rate was established. It was calculated that the parameters of critical compression ratios for intact castor beans were 6.2 and 3.6 for crushed seeds, which will provide a reliable data support for the design and operation of castor beans squeezer.