Alfa Laval’s UltraPure levitated Magnetic Mixer (MM) uses a strong magnetic field to levitate and rotate the impeller, thereby eliminating the need for complex bearings and seals and reducing the risk of fouling and downtime for cleaning and replacing components.
Inside the body of the impeller there are permanent magnets, which are coupled magnetically through the bottom of the mixing vessel to matching magnets in the drive unit. Consequently, no seal through the vessel is required. The impeller floats on a powerful magnetic field and rotates around a male bearing, which acts purely as a guide. Thanks to its levitation there is no direct contact between the female rotating bearing and the stationary male guide bearing. A motor mounted externally and operated via a frequency converter provides the drive.
Contactless rotation makes the MM much more efficient than conventional, mechanical mixers in several important ways, the company says.
- Without bearings or seals to worry about, the mixer can run dry. It can also cope with very low levels, ensuring that product is mixed to the last drop and fully homogenised.
- Since every drop that leaves the tank is fully mixed product, there is no residual waste. Consequently, there are no waste disposal costs and minimal environmental impact.
- The actual mixer incorporates eight wings to ensure gentle product treatment with minimal shear and to provide efficient pumping even at low rpm.
Unlike other magnetic mixers, the MM does not rely on electrical current to provide the magnetic field. The impeller therefore stays levitated at all times, even in the absence of liquid or electrical energy and does not need to be stopped for the CIP (clean-in-place) process.
