Gas-Assisted Oilseed Pressing on an Industrial Scale

In previous work, gas-assisted pressing (GAP) was evaluated in linear piston oil presses. These tests were important to determine optimal operating conditions and the effective mechanisms of GAP operations in modified-cage screw presses. To test whether this technique can be applied on an industrial scale, a GAP screw-press test run of rapeseed was performed on an industrial scale. Residual oil levels were reduced to 7.7 wt% by gas assistance at an average CO2 pressure of 12.5 MPa compared with 9.9 wt% achieved by conventional pressing with the same process. The high residual values were due to the cold pre-pressing nature of the experiment. The test run achieved a steady-state operation. Oil quality was improved, and a payback period of investment under these conditions was conservatively calculated to be approximately 3 years. A predictive model of the increase in oil yield achievable with gas assistance is presented, and the results indicate that a temperature decrease below 361 K results in an even better oil yield. Therefore, gas assistance is a promising technique for the cold pressing of oilseeds.