AGITATOR

 

(A)GITATOR:

     An agitator is a device which is used to import motion in the form of stirring to the liquids or semi solids. The agitator is a device which contains a shaft and an impeller/propeller. The shaft is connected to the gear box and the assembly is driven by motors using electricity.

The purpose of agitators can be for mixing liquids, solids, slurries, pastes, mixing liquids and gases, mixing solids and gases, promote chemical reactions, promote heat transfer, etc

   

:-Agitation Tank

 

 

Working of an Agitator:

                            The agitation is achieved by movement of the heterogeneous mass (liquid-solid phase),to the impeller. This is due to mechanical agitators, to the rotation of an impeller. The bulk can be composed of different substances and the aim of the operation is to blend it or to improve the efficiency of a reaction by a better contact between reactive product. Or the bulk is already blended and the aim of agitation is to increase a heat transfer or to maintain particles in suspension to avoid any deposit.

     An agitator is composed of a drive device ( motor, gear reducer, belts…), a guiding  system of the shaft (lantern fitted with bearings), a shaft and impellers .

An Impeller is a rotor that produces a sucking force, and is part of a pump.

    As the agitator moves in different directions, it pulls and  pushes the substances in the tank causing the substances to move.

An agitator is installed in the vessel to ensure that the contents in the vessel become uniform and homogeneous and remain in a proper mixed state. Since they have such wide variety of uses, the agitators are used in a multitude of industries such as chemical, process, food, pharmaceuticals, cosmetics, metal extractions, ink, paint etc.

 

Agitators are used in a variety of industrial processes such as for carrying out a chemical reaction, for mixing operations, for filtration, for drying, for heat exchange, etc. The agitators are able to cater to such wide variety of applications because there are a variety of impellers which come in different shapes and sizes.

 Types of Agitators

 

1.     Turbine Agitators

2.     Paddle Agitators

 3.     Anchor Agitators

 4.     Propeller Agitators

 5.     Helical Agitators

1.Turbine Agitator

These agitators have an axial input and the output is radial. Turbine agitators are very versatile; they are able to handle a wide variety of mixing operations because these agitators can create turbulent movement of the fluid due to the combination of rotational as well as centrifugal motion. They are popularly used in metal extraction industries and also for chemical reactions and have a very high blending efficiency. These are mostly used in chemical, pharmaceuticals, grease, cosmetics industries.

2. Paddle Agitator

It is one of the most basic types of agitator. It contains blades which are paddle shaped; the blades stretch throughout the vessel and reach the walls of the vessel. They are primarily used in applications where a uniform laminar flow of the liquids and little shearing is desired. This type of agitator is especially used for viscous materials. These are mostly used in food, chemicals, pharmaceuticals, sorbitol etc industries

3. Anchor Agitator

As the name indicates the shape of the impeller resembles that of the anchor. These agitators also extend and spread throughout the vessel such that there is very less clearance between the blades and the walls of the vessel. These agitators are also used when laminar flow conditions are desirable. These impellers sweep the whole batch because the blades are almost in physical contact with the walls of the vessels. These agitators are used in ink, paint and adhesive industries.

4. Paddle Agitator

These have impellers that similar to marine type propellers. They have blades which taper towards the shaft to minimize centrifugal force and to promote axial flow. It means when this agitator operates the motion of fluid is such that the inlet flow is parallel to the shaft and the outlet flow is also parallel to the shaft, the ideal flow is axial in nature. They are primarily used in applications to stir low viscosity liquids. They are used in pharmaceuticals industries and also other industries which use suspensions as the agitators don’t let the solid particles settle.

5.Helical Agitator

The blades of the helical agitators are arranged in a structure of helix. The appearance is similar to how a threaded screw looks. The motion of the liquids in this type of agitator is also axial in nature due to the way the blades or the ribbons move while helical agitator is in operation. There is a vigorous motion of the fluids within the vessel when the agitator is in operation. It is used in polymer industries and other industries which require the use of quite viscous materials.

Agitator in Industries:-

Agitators are machines used in industries that process products in the chemical, food, pharmaceutical and cosmetic industries, in a view of :

•     mixing liquids together

•     promote the reactions of chemical substances

•     keeping homogeneous liquid bulk during storage

•     increase heat transfer (heating or cooling)

References:-

1. Chemical Engineering World
2. Wikipedia
3. Youtube

Here is the animation video of agitator:-

https://youtu.be/rn9roXVDagY

 

 Written by:- Sagar Mangraj