Rotofoil H-series

Applications:

Viscosity range up to 5,000 mPa×s. Mixing miscible liquids, dissolving solids that are unlikely to agglomerate, preventing precipitation, heat dispersion, floc-culation.


Axial mixing with energy savings:
For the most mixing applications, it is essential to get a controlled uniform flow pattern in the entire batch. In reality, the solution is in a distinct axial flow pattern. A traditional impeller spreads the flow 45° or more. The ROTOFOIL impeller creates strong axial currents that follow the tank geometry all the way out in the corners and in this way transport even heavy particles upwards to avoid dead zones. Because of its efficient impeller design, ROTOFOIL offers energy savings up to 60%.


Smaller investment:
Thanks to the powerful axial flow of the ROTOFOIL, it can be placed higher in the tank than a traditional impeller - 1 to 2 impeller diameters or more from the bottom. This means a shorter shaft, a smaller shaft diameter and a smaller bearing stand. Thus we provide a smaller, easy-to-handle, and more cost effective agitator.

Hydrodynamics - the key to cutting energy cost:
Just like an airplane stalling, a mixer impeller will create turbulence from the back of its blades if their angle of attack is too steep. Turbulence at the impeller itself gives no flow but consumes a lot of power. The hydrodynamic ROTOFOIL transfers almost the entire energy input into motion of the liquid; a minimum of energy is wasted on turbulence.


Characteristics of the ROTOFOIL blade:


Increasing width:
The blade is slim at the tip - where the speed is greatest and wider at the base where the speed is lowest. The blade profile assures uniform flow from the entire length of the blade as each segment has a similar pumping capability.


The twist:
The twist gives the blade an evenly decreasing angle from the hub out to where the velocity is higher, carefully proportioned to avoid turbulence anywhere on the diameter of the ROTOFOIL.


The arch:
The arch has two functions. It allows a higher average blade angle since the leading edge "attacking the liquid" is angled lower than the trailing edge directing powerful currents downwards. The arc also strengthens the blade. Actually it makes the blade four times stronger. That´s why we can use a lighter material when making the ROTOFOIL. A ROTOFOIL impeller only weighs about one third of a traditional impeller of the same diameter and the blade thickness is half the size. The thin blades further contribute to reducing power consumption.


The table shows an example of an actual mixing job performed by a Pitch Blade Turbine, a Marine Type Propeller and a ROTOFOIL.


Pitch Blade Turbine Marine Propeller ROTOFOIL
RPM 300 300 300
Impeller diameter 415 mm 450 mm 500 mm
Flow rate 21.1 m3 / min 21.5 m3 / min 22.1 m3 / min
Power draw 2.03 kW 0.96 kW 0.69 kW
Required shaft length 2500 mm 2450 mm 1500 mm
Required shaft diam. 55 mm 45 mm 30 mm
Agitator weight 148 kg 96 kg 43 kg
Agitator puchase price factor 1.00 0.74 0.49
Flow per kW 10.4 m3 / min 22.4 m3 / min 32 m3 / min