DESIGN OF SMALL-RATE FEEDERS FOR NON-FREE-FLOWING MATERIALS - A CASE-STUDY

This paper uses a case study to illustrate the problems which can occu r when using small feeders to dose at low rates, with materials which are not totally free flowing. The general principles of good design fo r small feeders are enlarged upon, together with issues to look for wh en trouble shooting these equipment items. The system in question used a screw to dose a moist pelleted talc into a process at a nominal rat e which was variable at around 1 t/h and originally suffered from poor flow in the hopper, a variable dosing rate and binding of the screw, thus needing constant attention from the operator to keep it working. Various types of mechanical flow assistance device had been tried, mos t of which made the problem worse. The Wolfson Centre redesigned the s crew and hopper of the unit, and the performance problems were cleared . The problems with the original and intermediate designs serve to ill ustrate very well the points that need to be observed, in obtaining go od performance from small feeders.