“ START WITH THE NAME OF ALLAH WHO IS THE MOST BENEFICENT

AND MOST MERCIFUL.”

IHSAN ALI WASSAN (14CH18)

DISCIPLINE: CHEMICAL ENGINEERING

SUBJECT:

UNIT OPERATIONS-I

QUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE AND TECHNOLOGY NAWABSHAH, SINDH

PAKISTAN

AGITATION AND MIXING

PRESENTATION OUTLINE

-Definitions -Purposes of agitation -Devices to produce agitation -Conclusion

DEFINITIONS

AGITATION It refers to the induced motion of a

“homogenous” material in a specified way, usually in circulatory pattern inside some sort of container.

MIXING Mixing the random distribution, into and

through one another, of two or more initially separate phases.

PURPOSES OF AGITATION

Suspending solid particles Blending miscible liquids Dispersing a gas through the liquid Dispersing a second liquid to form an

emulsion or suspension Promoting heat transfer

DEVICES TO PRODUCE AGITATION

IMPELLERS

DEFINITION The rotating part of a centrifugal pump,

compressor, or other machine designed to move a fluid by rotation is called Impeller.

OR A rotor used to increase (or decrease in

case of turbines) the pressure and flow of a fluid.

OR A device turned by the flow of water past

a ship's hull, used to measure speed or distance travelled.

IMPELLERS Impeller agitators divided into two

classes.

AXIAL-FLOW IMPELLERS Those impellers that generate currents

parallel with the axis of the impeller shaft are called Axial-Flow Impellers.

Axial-flow impeller

RADIAL-FLOW IMPELLERS Those impellers that generate currents

an a radial or tangential direction are called radial flow impellers.

Radial-flow impellers

Three main types of impellers for low-to moderate viscosity liquids are.

TYPES OF IMPELLERS

PROPELLERS A propeller is an axial-flow, high speed

impeller for liquids of low viscosity.

Small propellers turn at full speed either 1,150 or 1,750 rpm.

Larger propellers turn at 400 to 800 rpm.

PROPELLERS (cont…..) The ratio of distance to the propeller

diameter is known as pitch of the propeller.

A propeller with a pitch 1.0 is said to have square pitch.

Propellers rarely exceeds 18 inch in diameter.

TURBINESThere are 4 types of turbine impeller

The straight-blade turbine Disc turbine Concave blade CD-6 disc turbine Pitched-blade turbine

The straight-blade turbine The simple pushes the

liquid radially and tangentially with almost no vertical motion at the impeller.

The current it generate travel outward to the vessel wall and then flow either upward or downward.

Such impellers sometimes called paddles.

straight-blade turbine

Disc turbine The disc turbine with multiple straight

blades mounded on a horizontal disc.

Useful for dispersing a gas in a liquid.

Concave blade CD-6 disc turbine

It is also used for gas dispersion.

Consists of six concave blades.

Pitched-blade turbine

Used when good overall circulation important.

Because it provides some axial flow in addition to the radial flow.

HIGH EFFICENCY IMPELLERS

The high efficiency impeller HE-3 has three slanted blades that are crimped to decrease the blade angle near the tip.

The A310 fluid foil impeller uses air foil shaped blades with taper so that they are narrower at the tip than their edges.

Used to mix low-or moderate-viscosity liquids.

CONCLUSION In the whole it is concluded that during

agitation or mixing process “ Impellers agitators are widely used to circulate the liquid through the vessel in which the dispersion of liquids and gases into other liquids like mixing of stiff paste, elastomers and dry solids powders takes place.”

Thank You Everyone