Turbines are mechanical devices that mix different fluids with blades and impellers.
Turbines are used for mixing high viscosity liquids because of the greater shear forces produced by them than the propellers.
They are used especially for the preparation of emulsion. For preventing vortex formation, baffles are often used.
Construction
¨ Turbines consist of a circular disc having short blades attached to it Their diameter is 30- 50% of the vessel diameter. They rotate at 50-200rpm speed speed (less than the propellers). Different turbines have blades of different shapes, like straight, curved, pitched, or vertical..
Working
¨ Turbines operate similarly to a centrifugal pump working in a vessel against negligible back pressure.
¨ Mixing is accomplished by the turbine blades, which constrain and discharge the liquid
Applications
¨ Due to high shear forces, they are effective for high viscous solutions, e.g., syrups, glycerine, etc.
¨ They are suitable for liquids of large volume and high viscosity.
Merits
- They provide greater shearing forces than propellers, So the pumping rate is less; therefore, they are suitable for emulsification.
- They do not damage dispersed particles at economical speeds.
Demerits
Due to the absence of vertical flow, they are less suitable for suspension.
They are expensive to fabricate and are restricted to a narrow range of speeds
They are expensive.
