Influence of rheological properties of stirred liquids on the axial and tangential forces in a vessel with a PMT impeller

Based on literature information, the role of both tangential and axial forces in stirred liquids on the formation of circulation regions is discussed. Rheological measurements of seven applied liquids show that five liquids are pure Newtonian and two other liquids exhibit shear-thinning rheology. Those liquids are used in experiments in a baffled vessel stirred by a Prochem Maxflo T (PMT) type impeller in a broad range of its rotational speed. Both the tangential and axial forces, exerted by the impeller on the stirred liquids, are calculated on the basis of measured values of torque and apparent mass change of the stirred tank for the studied range of agitator speed. The total, resultant force is also calculated. A significant impact of the stirred liquid viscosity on the relationship of the three forces vs. the impeller power consumption is determined. Relationships of the three forces on the impeller power are also analysed and relevant correlation equations are proposed.