466733 Continuous Wet Granulation in a Twin Screw Extruder: Effect of Process Variables on Residence Time Distribution and Granule Characteristics
Here we analyse the dependence of the residence time and granule size distribution (GSD) in a twin screw granulator on process parameters (screw speed, powder feed rate, liquid-to-solid ratio) and screw configuration (conveying, kneading, and cutting elements). The formulation was granulated in a 12 mm twin screw extruder (Three-Tec, Switzerland) with a length-to-diameter ratio of 40, using water as the granulating liquid. GSD was measured using a laser diffraction technique, while the residence time distribution was measured by adding a small dose of dye into the powder feeding port during steady state operation, followed by the sampling cup method described elsewhere. Parameter values were chosen using a d-optimal factorial design to identify the most important parameters, and the results were rationalised to elucidate the granulation mechanisms in the different screw regions/screw elements.
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