EXTRUSION OF DEFATTED SOY FLAKES - MODEL OF A PLUG FLOW PROCESS

Observation of defatted soy flakes contained in the screw channel of an extruder suggested that the soy flakes were being conveyed as a powder and that a plug flow model should describe the process. Flow rates from an extruder, operating at low temperature (30-50°C), were measured for different die sizes, screw speeds, and feed moistures. Dynamic coefficients of friction for different moisture soy flakes on stainless steel and hard chrome plate were determined. The Darnel and Mol model of plug flow in solids conveying was then used to calculate theoretical outputs, which were in good agreement with the experimental results. Output rates versus die pressure indicated extremely pseudoplastic flow approaching plug flow (slip) through the die. © 1979, The Society of Rheology. All rights reserved.