Types of Agitators

propeller agitator and free calculator for power consumptionPropeller agitators are commonly made of three-bladed attached to the main shaft. They are flexible in operations and mostly used in the mechanical mixing of low to medium viscosity fluids. These type of propellers are also called as marine type propellers. The diameter of the propellers depends on the rotational speed and diameter of the batch reactor or the agitator vessel. Depending on the agitator vessel size and the fluid viscosity the power consumption of the propeller agitator may exceed more than 50kW.                         
turbine impeller and mixing intensity calculatorpitched turbine Turbine impellers operate at low speed and are much larger than propellers. Turbine has an excellent feature in designing the flow pattern where a change in design can divert the flow pattern of fluid by radial flow or axial flow in the reactor vessel. Based on the configuration of the impeller blades these flow patterns can be achieved. The radial design makes the fluid to flow at high velocity in radial direction whereas axial impellers use pitched blades, make the fluid to flow parallel to shaft in the downward direction and then push the fluid towards the wall of the agitator vessel. For gas dispersion operation radial turbine impeller is used and axial turbine impeller is used for chemical reactions, suspension solid and miscible liquid mixing. 

anchor type agitator and a calculator for calculating power and mixing requirement

Types of agitators models, application and comparison:

Agitator models Application Advantages Disadvantages
  • Flat paddles
  • Finger paddles
  • Gate paddles
  • Solid mixing
  • Slurry mixing
  • Heavy duty mixing
  • Adjustable to 2 or 4 blades
  • Excellent for low-speed
  • High power consumption
  • Inefficient liquid circulation
Counter-rotating paddles Paste mixing
  • Efficient in the laminar condition
  • Blending
  • Vibrates at high speed
  • Not suitable for liquid mixing
Tumbling Blending Paste and viscous material mixing Not suitable for  fluid solutions
Disk and cone Polymers and dispersion preparation Viscous solution mixing with 60 revolutions per second Paste mass cannot be handled
Free shaft suspension Sugar processing Suspension, Thickening operation High power requirement
Impeller type Emulsion preparations
  • Good temperature control
  • Creates axial flow
  • Good phase mixing
Not for viscous materials
Turbine agitator
  • Straight blade
  • Pitched blade
  • Vaned disk
  • Curved blade
Liquid and gas reactions
  • Excellent for dispersion operations
  • Creates good radial flow
Only for less viscous liquid below 15 to 20 Ns/m2
Slotted rotary
  • Rotating disk
Powders and
Unique particle size and homogeny product formation
  • Minimum axial flow
  • Operates better only for 0.1 to 0.01mm particle size solids
  • Screw in cone
Food and snack processing Homogenization of high viscous materials Not suitable for miscibility operations
  • Ribbon type
  • Helical screw
Polymer and paints processing Handles viscoelastic liquids that are more than 20 Ns/m2 Less radial flow patterns
Gate Blending operations
  • Good speed control
  • Handles pseudoplastic liquids
Not suitable for gas to liquid operations
  • Round anchor
  • Combine anchor and gate
Milk and fat processing Efficient heat exchange between the reactor walls and reaction mass (fluids)
  • High power consumption
  • Requires heavy duty gearbox
  • Dairy and food processing
  • Chemicals processing
  • Less  Metzner –Ott shear rate constant
  • Homogenization
  • Good miscibility
  • Motion of liquid starts on one spot
  • Dead spots formation at high rotation speeds
  • The occurrence of solids settling at low speeds