Concept

Agitators are widely used in industries like chemical, food, pharmaceutical and cosmetics for mixing of various fluids to achieve desire products. It’s machine having different blades arrangement on a rotating shaft for creating turbulence within the fluids containing in Reactor ,Vessel or Tank.

Mixing may be defined as the process in which two or more than two components in a separate or roughly mixed condition are treated in such a way so that each particle of any one ingredient lies as nearly as possible to the adjacent particles of other ingredients or components. This process may involve the mixing of gases, liquids or solids in any possible combination and in any possible ratio of two or more components.

Necessity of Mixing

Mixing can be done for the following reasons:

• To ensure that there is uniformity of composition between the mixed ingredients which may be determined by taking samples from the bulk material and analyzing them, which should represent overall composition of the mixture.
• To initiate or to enhance the physical or chemical reactions e.g. diffusion, dissolution etc.

Product of Mixing

Generally mixing is carried out to obtain following type of products:

• When two or more than two miscible liquids are mixed together, this results into a solution known as true solution.
• When two immiscible liquids are mixed in the presence of an emulsifying agent, an emulsion is produced.
• When a solid is dissolved in a vehicle, a solution is obtained
• When an insoluble solid is mixed with a vehicle, a suspension is obtained.
• When a solid or liquid is mixed with a semisolid base, an ointment or a suppository is produced.
• When two or more than two solid substances are mixed together, a powder is obtained which when filled into capsule shell is known as capsules and when compressed under heavy pressure is called tablet.

Applications

• Dispersion of immiscible liquids.
• Gas Liquid Contacting.
• Gas-Gas Mixing.
• Mixing of Liquids of extreme Viscosity ratio.
• Turbulent Mixing of miscible low Viscosity liquid.

Selection of Agitator

Selection of Agitator for mixing is based on the process parameters (density and Viscosity of fluid), Geometry of Tank, mixing time, temperature etc. To fix the Diameter of Impeller some of the thumb rule has to follow.

Re= D² N_р/µ,
D= Diameter of Impeller (m)
N= Speed of Impeller (RPS)
Р= Density of Fluid (Kg/M3)
µ= Viscosity of Fluid. (Pa.s)

For Higher Reynolds No, select Turbine or Propeller and for lower Reynolds No. Select Helical, Ribbon or Screw type Impeller.

Power number NP vs. Reynolds number Re for turbines and Impellers

Po=N_р x D⁵ x N³ x p,
Where p=Density of Fluid(kg/m³),
Po=power in watt

Material of Construction

• Carbon Steel
• Carbon Steel + FRP
• Carbon Steel + PVC
• Carbon Steel + Rubber Lined
• Carbon Steel + Epoxy Coating
• Stainless Steel ( SS 304,SS 304L,SS 316,SS 316L)
• Special Alloys.
• Hastealloy
• Titanium

Mounting Arrangement

• Foot mounted Motor with Gear Box
• Flanged mounted Geared Motor
• With and Without Bottom Bush
• Wall mounted
• Side entry with retracting type Mechanical Seal
• Chain / Hoist mounted.
• Portable clamp mounting
• Detachable coupling.