Flow property measurement of food powders and sensitivity of Jenike’s hopper design methodology to the measured values

Abstract

The flow properties and powder physical properties were measured for 13 food powders. The flow properties were measured using shear cell techniques, and the powder physical properties measured were particle size, moisture, bulk and particle densities. The flowability of the food powders, as characterised by flow index, varied from easy flow to very cohesive. Particle size and moisture content do affect flowability, however there was no strong relationship for trying to relate the flowability of the food powders based solely on these physical properties. There was no relationship between measured powder physical properties and their wall friction characteristics. As a result, surface forces between the powder particles, and between particles and the wall surface play an important role in determining the flow nature of the powders, and this is an area requiring research. Jenike’s mathematical analysis to determine the minimum hopper angle and opening size for mass flow is the engineering standard practice for designing a hopper. Applying this analysis, using values of the measured food powder flow properties, shows that this can occasionally produce some unexpected values for the hopper opening size.