Modelling of powder hydrodynamics in a screw reactor

Abstract

Screw reactors are largely used devices in the industry. Very few studies focus on the powder hydrodynamics in screw reactors. The overflow point, a filling degree value when the powder passes over the shaft, was determined for different conditions and a dimensionless model was fitted to predict this parameter. The residence time distribution (RTD) has been measured with a pulse injection of salty powder. The influence of operating conditions and geometry parameters on the RTD has been studied. It appeared that the Hausner ratio, the pitch length and the filling degree mostly influence the RTD shape. Two models for the RTD have been compared: the compartment model was the most accurate and has one parameter of adjustment. A dimensionless model was developed and fitted with 51 experimental RTD results, predicting the RTD shape. The dimensionless model predicts with good accuracy other experimental data from the literature.