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[March 2003]
Impeller for Mixing Shear Thinning Fluids
The 'Counterflow' impeller from Mixing Solutions Ltd (Newbury, Berks, England) has been designed to improve mixing performance and to reduce blend times, particularly for high-viscosity shear thinning fluids, whilst offering substantial energy savings over conventional open impellers.Said to be easily retrofitted to existing agitators, these impellers operate at considerably higher impeller-to-tank diameter ratios. Mixing Solutions says that this is a significant advantage with shear thinning fluids where stagnancy at the vessel wall can be a problem.
Internal and external blades create counterflow by pumping both upwards and downwards, providing dependable product consistency in shorter cycle times. They eliminate stagnant zones at low power.
The impellers are claimed to ideal for applications where non-Newtonian fluid properties or wide viscosity changes are encountered. Used in heat transfer applications, they are claimed to provide up to 200% improvement over standard impellers.
The ability to mix difficult high viscosity/shear thinning and water-like fluids in the same vessel with or without baffles makes them ideal for make-up vessels. They also offer controlled vortexing and adjustable local dissipation and can replace helical ribbon and anchor impellers in high viscosity applications.
Maintenance costs are said to be reduced as the slower rotating speed of these impellers will increase the life cycle of both seals and equipment.
ENDS