Modelling interaction between cane particles during high rate pneumatic cane cleaning

A dense phase model to investigate the performance of pneumatic cane cleaning devices operating at high pour rates, has been developed. Initially a model of a single impact between two flexible cane particles was developed. Using dimensional analysis it was shown that impact forces and contact times for such an event could be characterised by just two dimensionless terms. Impact characteristics obtained by correlating the data from the single impact model were subsequently incorporated into a multiple particle model. The results of a parametric study using the multiple particle model indicated that the greatest potential for improvement lay in controlling the motion of the particles as they emerged from the chopper into the extraction chamber. Most notably, a critical chopper speed was identified above which extraction efficiency deteriorates markedly. Reducing billet rotation at the chopper would significantly improve separation efficiency. A billet stream greater than a single layer thick emerging from the chopper was found to produce highly variable separation efficiencies. The rigidity of the leaves alone (a factor dependant in part on whether the leaves were green or dry) was found to have little effect on separation.