Turbine Mixer (Pharmaceutics | Chapter-4): Latest D Pharma 1st year Notes

Turbine Mixer

A turbine mixer is a mechanical device that is used in mixing different types of liquids. The turbine mixer works mainly on the principle of shearing action.

A turbine consists of a circular disc to which a number of short blades are attached. The diameter of the turbine ranges from 30% to 50% of the diameter of the vessel.
It rotates at a lower speed than propeller (50-200 R.P.M).
The blades may be straight, curved, pitched or vertical.

A flat bladed turbine produces radial and tangential flow, but as speed increase radial flow dominates. A pitched blade turbine produces axial flow.
Near the impeller, the zone of rapid currents high turbulence and intense shear is observed. The shear produced by turbines can be further enhanced using a diffuser ring.
A diffuser ring is a stationary perforated or slotted ring, which surrounds the turbine. It increase shear forces, the liquid passes through the perforations reducing rotational swirling and vortexing.

Turbines are effective for high viscous solutions with a very wide range of viscosities up to 700 Pascal/seconds (syrups, liquid paraffin, glycerin etc).
They can handle slurries with 60% solids.
Turbines are suitable are suitable for liquids of large volume and high viscosity, if the tank is baffled.

Turbine gives greater shearing forces than propellers, through the pumping rate is less. Therefore, turbines are suitable for emulsification.