Effect of propeller use on residence time distribution (rtd) in single-screw cam-flow rice semolina extrusion

Abstract

The influence of the speed of the feeding (Nf) and main (Nw) screw, the moisture content of the material (W) and the temperature of the die (Tm) on the average residence time (t) and the Peclet number (Pe) in single-screw extrusion of rice semolina using a propeller were investigated. A computer system with a camera was used to continuously read the colorant saturation as a tracer pulsed into the feed zone of the extruder. The differential distribution curves of dwell times were constructed. The responce surface methodology with an orthogonal central compositional plan was used. Regression equations were obtained describing the influence of the selected independent variables on the average residence time (t) and the Peclet number (Pe). It has been found that the use of a propeller increases the mixing capability of the extruder and brings it closer to the ideal mixer.