THE EFFECT OF FILL LEVEL ON POWDER MIXER PERFORMANCE USING A POSITRON CAMERA

The technique of positron emission particle tracking was used to study the influence of fill level on the particulate motion in a 5 l ploughshare batch mixer. The average tangential velocity was found to increase linearly with increasing fill, whereas the r.m.s. axial velocity decreased. Above 10% fill, the axial motion developed into two circulation cells, with particles transferring occasionally between the two. Varying the size of the tracer particle had little effect on the velocity estimates or on the residence time distributions found. The axial mixing time increased with increasing fill, and showed some dependence on tracer size.