INFLUENCE OF DESIGN ON DISPERSIVE MIXING PERFORMANCE IN AN AXIAL DISCHARGE CONTINUOUS MIXER - LCMAX-40

The axial discharge continuous mixer combines the features of a contin uous mixer and a twin screw extruder, expanding the flexibility of thi s compounding machine. In this work we analyzed the influence of rotor design on the dispersive mixing performance of a LCMAX 40 unit. Speci fically we looked at various arrangements for the pushing and counter pushing units in the design of the LCMAX 40. A fluid dynamics analysis package-FIDAP, based on the finite element method, was used to model the flow behavior of a power law model fluid under different pressuriz ation conditions. Dispersive mixing efficiency was quantified in terms of shear stresses and elongational now components generated in the fl ow field. We found that the counter-pushing unit generally contributes more in building up high shea. stresses. However, the generation of e longational now components, which is beneficial for dispersive mixing, is not solely dependent upon the pushing-counter pushing configuratio n but rather on the overall rotor geometry. We found that the maximum number of counter-pushing units in the rotor design of the LCMAX 40 sh ould not exceed two in order to provide adequate material pumping. Rot or designs with alternating arrangements of pushing and counter-pushin g units provide overall better dispersive mixing conditions.