This document discusses fluid dynamics and agitation. It defines the difference between agitation and mixing, and describes the purposes of agitation such as suspending solids, blending liquids, and enhancing heat and mass transfer. It also discusses agitator vessel design including the vessel, baffles, impellers and motor. Different types of impellers like axial and radial flow impellers are described. Factors affecting agitator design and applications of agitation in industries are summarized.

2. FLUID DYNAMICS

3. GROUP
NO 2
• MUHAMMAD FEROZ 2017-CH-
720
• IHTASHAM MEHMOOD 2017-
CH-719
• ADEEL AKRAM 2017-
CH-718
• MALIK ANNAS 2017-
CH-732
• UBAID-UL-REHMAN 2017-
CH-710

4. DIFFERENCE B/W AGITATION AND MIXING
• AGITATION
IT REFERS TO THE INDUCED
MOTION OF A “HOMOGENOUS”
MATERIAL IN A SPECIFIED WAY.
• MIXING
IT RANDOM DISTRIBUTION, INTO
AND THROUGH ONE ANOTHER,
OF TWO OR MORE INITIALLY
SEPARATE PHASES.

5. 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
• ENHANCEMENT OF MASS TRANSFER BETWEEN DISPERSED
PHASES.

6. AGITATOR VESSEL
• INTRODUCTION
 AN AGITATOR IS SOMETHING WHICH IS USED TO STIR LIQUID OR
MIXTURE OF LIQUIDS.
IT CAN BE USED IN VARIOUS OPERATIONS, IN A PHARMA INDUSTRY IT
CAN BE USED IN MULTIPLE OPERATIONS LIKE REACTIONS, DRYING,
FILTRATION, ETC.
AGITATION IS THE PROCESS OF KEEPING A MIXTURE THAT HAS BEEN
MIXED IN THE PROPER MIXED STATE REQUIRED FOR THE 'END' PRODUCT

7. A BACIS AGITATOR VESSEL DESIGN

8. PRINCIPLE OF AGITATION
• 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.

9. A BACIS AGITATOR VESSEL DESIGN
•THE VESSEL
• BAFFLES
• IMPELLER
•MOTOR

10. THE VESSEL
• A DISHED BOTTOM REQUIRES LESS POWER THAN A FLAT ONE. ECONOMIC
AND MANUFACTURING CONSIDERATIONS, HOWEVER, OFTEN DICTATE
HIGHER RATIOS OF DEPTH TO DIAMETER.

11. IMPELLERS
• AN IMPELLER IS A ROTATING COMPONENT OF A CENTRIFUGAL PUMP
WHICH TRANSFERS ENERGY FROM THE MOTOR THAT DRIVES THE PUMP
TO THE FLUID BEING PUMPED BY ACCELERATING THE FLUID OUTWARDS
FROM THE CENTER OF ROTATION. THE VELOCITY ACHIEVED BY THE
IMPELLER TRANSFERS INTO PRESSURE WHEN THE OUTWARD
MOVEMENT OF THE FLUID IS CONFINED BY THE PUMP CASING.
IMPELLERS ARE USUALLY SHORT CYLINDERS WITH AN OPEN INLET
(CALLED AN EYE) TO ACCEPT INCOMING FLUID, VANES TO PUSH THE
FLUID RADIALLY, AND A SPLINED, KEYED, OR THREADED BORE TO ACCEPT
A DRIVE-SHAFT.

12. TYPES OF IMPELLERS
• THERE ARE TWO TYPES OF IMPELLERS, DEPENDING ON THE FLOW REGIME CREATED
(SEE FIGURE):
AXIAL FLOW IMPELLER
RADIAL FLOW IMPELLER

13. TYPES OF IMPELLERS
1. GENERATE CURRENTS PARALLEL WITH THE AXIS OF IMPELLER SHAFT
AXIAL-FLOW IMPELLER.
2. GENERATE CURRENTS IN A RADIAL OR TANGENTIAL DIRECTION
RADIAL FLOW IMPELLERS.
• AXIAL FLOW IMPELLERS IMPOSE BASICALLY BULK MOTION, AND ARE
USED IN HOMOGENIZATION PROCESSES .
• RADIAL FLOW IMPELLERS IMPOSE SHEAR STRESS TO THE FLUID,
AND ARE USED TO MIX IMMISCIBLE LIQUIDS.

14. TYPES OF IMPELLERS
• IMPELLERS CAN BE FURTHER CLASSIFIED PRINCIPALLY INTO THREE SUB-
TYPES
• PROPELLERS
• PADDLES
• TURBINES

15. IMPELLER SIZE
• THIS DEPENDS ON THE KIND OF IMPELLER AND OPERATING CONDITIONS
DESCRIBED BY THE REYNOLDS, FROUDE, AND POWER NUMBERS AS
WELL AS INDIVIDUAL CHARACTERISTICS WHOSE EFFECTS HAVE BEEN
CORRELATED. FOR THE POPULAR TURBINE IMPELLER, THE RATIO OF
DIAMETERS OF IMPELLER AND VESSEL FALLS IN THE RANGE, D/DT=0.3-
0.6, THE LOWER VALUES AT HIGH RPM, IN GAS DISPERSION, FOR
EXAMPLE.
• IMPELLER SPEED
• WITH COMMERCIALLY AVAILABLE MOTORS AND SPEED REDUCERS,
STANDARD SPEEDS ARE 37, 45, 56, 68, 84, 100, 125, 155,190, AND 320
RPM.

16. BAFFLES
• BAFFLES ARE NEEDED TO PREVENT VORTEXING AND ROTATION OF
THE LIQUID MASS AS A WHOLE. A BAFFLE WIDTH ONE-TWELFTH THE
TANK DIAMETER, W = DT/12; A LENGTH EXTENDING FROM ONE
HALF THE IMPELLER DIAMETER, D/2, FROM THE TANGENT LINE AT
THE BOTTOM TO THE LIQUID LEVEL, BUT SOMETIMES TERMINATED
JUST ABOVE THE LEVEL OF THE EYE OF THE UPPERMOST IMPELLER.

17. BAFFLES

18. VORTEX
• IF SOLID PARTICLES PRESENT WITHIN TANK; IT TENDS TO THROW THE
PARTICLES TO THE OUTSIDE BY CENTRIFUGAL FORCE. POWER ABSORBED BY
LIQUID IS LIMITED. AT HIGH IMPELLER SPEEDS, THE VORTEX MAY BE SO DEEP
THAT IT REACHES THE IMPELLER.

19. PREVENTING VORTEX
• BAFFLES ON THE TANK WALLS  IMPELLER IN AN ANGULAR OFF-
CENTER POSITION.

20. MOTOR
• A MOTOR IS AN ELECTRICAL MACHINE THAT ELECTRICAL
ENERGY INTO MECHANICAL ENERGY.

21. A GOOD MIXING SHOULD ACHIEVE THE
FOLLOWING
1.MINIMUM POWER REQUIREMENT.
2.EFFICIENT MIXING IN OPTIMUM TIME.
3.BEST POSSIBLE ECONOMY.
4.MINIMUM MAINTENANCE, DURABLE AND TROUBLE FREE OPERATION.

22. FACTORS AFFECTING THE DESIGNING OF THE
AGITATOR:
1. TYPE OF VESSEL
2. CIRCULATION PATTERN.
3. LOCATION OF THE AGITATOR
4. SHAPE AND SIZE OF THE VESSEL
5. DIAMETER AND WIDTH OF THE AGITATOR
6. METHOD OF BAFFLING
7. POWER REQUIRED
8. SHAFT OVERHANG
9. TYPE OF STUFFING BOX OR SEAL, BEARING, DRIVE SYSTEM ETC

23. MIXING OF LIQUIDS
• SINCE NATURAL DIFFUSION IN LIQUIDS IS RELATIVELY SLOW, LIQUID MIXING IS
MOST COMMONLY ACCOMPLISHED BY ROTATING AN AGITATOR IN THE LIQUID
CONFINED IN A TANK. IT IS POSSIBLE TO WASTE MUCH OF THIS INPUT OF
MECHANICAL ENERGY IF THE WRONG KIND OF AGITATOR IS USED.
• IN GENERAL, AGITATORS CAN BE CLASSIFIED INTO THE
• FOLLOWING TWO GROUPS.
1.AGITATORS WITH A SMALL BLADE AREA WHICH ROTATE AT HIGH SPEEDS.
THESE INCLUDE TURBINES AND MARINE TYPE PROPELLERS.
2.AGITATORS WITH A LARGE BLADE AREA WHICH ROTATE AT LOW SPEEDS.
INCLUDE ANCHORS, PADDLES AND HELICAL SCREWS.

24. • SMALL BLADE HIGH SPEED AGITATORS ARE USED TO MIX LOW TO MEDIUM VISCOSITY
LIQUIDS. TWO OF THE MOST COMMON TYPES ARE THE SIX-BLADE FLAT BLADE TURBINE
AND THE MARINE TYPE PROPELLER. FLAT BLADE TURBINES USED TO MIX LIQUIDS IN
BAFFLED TANKS PRODUCE RADIAL FLOW PATTERNS PRIMARILY PERPENDICULAR TO THE
VESSEL WALL. IN CONTRAST MARINE TYPE PROPELLERS USED TO MIX LIQUIDS IN BAFFLED
TANKS PRODUCE AXIAL FLOW PATTERNS PRIMARILY PARALLEL TO THE VESSEL WALL.
SMALL BLADE HIGH SPEED AGITATORS

25. LARGE BLADE LOW SPEED AGITATORS
• LARGE BLADE LOW SPEED AGITATORS INCLUDE ANCHORS, GATES, PADDLES, HELICAL
RIBBONS AND HELICAL SCREWS. THEY ARE USED TO MIX RELATIVELY HIGH VISCOSITY
LIQUIDS AND DEPEND ON A LARGE BLADE AREA TO PRODUCE LIQUID MOVEMENT
THROUGHOUT A TANK. SINCE THEY ARE LOW SHEAR AGITATORS THEY ARE USEFUL FOR
MIXING SHEAR THICKENING LIQUIDS.

26. INDUSTRIAL APPLICATION OF AGITATION
 BLENDING OF TWO MISCIBLE LIQUIDS AS ETHYL ALCOHOL AND
WATER
 DISSOLVING SOLIDS IN LIQUIDS, SUCH AS SALT IN WATER
 DISPERSING A GAS IN A LIQUID
 LIQUID-LIQUID DISPERSION, SUCH AS DISPERSION OF PIGMENT IN
SOLVENTS
 SUSPENDING OF FINE SOLID PARTICLES IN A LIQUID, AS IN CATALYTIC
HYDROGENATION OF A LIQUID
 AGITATION OF THE FLUID TO INCREASE HEAT TRANSFER BETWEEN
THE FLUID AND A COIL OR JACKET IN THE VESSEL WALL.