“ 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