Mixing impellers and impeller systems for mixing and blending liquids and liquid suspensions having a wide range of viscosities

摘要

The impellers have a plurality of fluidfoil blades (12,14,16) and have camber and twist. The geometric pitch or blade angle increases from the tip (24) of the blade towards their axis of rotation in a manner to provide an over pitched condition so that the pitch ratio of the blades at 40% of the blade radius from the axis is greater than the pitch ratio at the tip. The blades are preferably smoothly tapered and increased in width from the tip towards the axis. The impeller blades are mounted on a hub (18) connected to a drive shaft. The blades may decrease in width where they connect to the hub. The pitch angle at the tip is in the range of 18 DEG to 30 DEG (preferably about 20 DEG ). The angle at the tip of two diametrically disposed blades of a four blade impeller may have a different blade angle at the tip than the other pair of blades. A pair of impellers may be used. These impellers may be of different diameter and disposed in close proximity so that they are in dependent relationship (preferably spaced apart by less than the diameter of the larger impeller). IMAGE