Twin screw extruder (TSE) has been studied extensively as a granulator because it allows continuous processing. Initial work was carried out by comparing the TSE with conventional granulator shows that the mechanism of TSE granulation is different from conventional granulation with the absence of the consolidation stage. PEPT was also utilised and it reveals that the flow stream of the material is not only due to the conveying capacity but also the granulator fill, in particularly for the 90o mixing zone which is believed to be a dispersion type of mechanism driven by the granulator fill gradient. Residence time distribution was measured and simulated by fitting the experimental data using a continuous stirred tank reactors model. The model describes the experimental curves reasonably well when a plug flow fraction was considered. Generally the mean residence time (MRT) of the system is proportional to the mixing zone angle and is inversely proportional to the screw speeds and flowrate. A study using the variance reduction ratio demonstrates that the TSE granulator used in the present study is able to remove the feed instability given that the ratio of the frequency of the input stream fluctuation to the MRT is high.
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