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PUMPS PUMPS Unit -IV Unit -IV CHE216: MOMENTUM CHE216: MOMENTUM TRANSFER TRANSFER
28

Fluid Mechanics- Pumps

Nov 21, 2014

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Regarding Pumps, especially for chemical engineering

Written by

K.Samba Siva Rao,
Lecturer,
Dept. of chemical engineering
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Page 1: Fluid Mechanics- Pumps

PUMPSPUMPSUnit -IVUnit -IV

CHE216: MOMENTUM CHE216: MOMENTUM TRANSFERTRANSFER

Page 2: Fluid Mechanics- Pumps

PRESENTATION OUTLINEPRESENTATION OUTLINE

Pump TerminologyPump Terminology Pump Classification:Pump Classification: - Reciprocating Pumps- Reciprocating Pumps - Rotary Pumps- Rotary Pumps - Centrifugal Pumps- Centrifugal Pumps Pumping ProblemsPumping Problems Power and Efficiency CalculationsPower and Efficiency Calculations Pump SelectionPump Selection

Page 3: Fluid Mechanics- Pumps

PUMP TERMINOLOGYPUMP TERMINOLOGY

PumpingPumping, , the addition of energy to athe addition of energy to a fluid fluid

Pumping action creates a partial vacuum while Pumping action creates a partial vacuum while atmospheric pressure forces liquid up.atmospheric pressure forces liquid up.

Pump performancePump performance, , specified in terms of Q and specified in terms of Q and HH::

)()

22()(/

22,,

sdsdgsgd ZZg

V

g

VPPtQH

Page 4: Fluid Mechanics- Pumps

DisplacementDisplacement,, the discharge of a fluid from a the discharge of a fluid from a vesselvessel

Centrifugal ForceCentrifugal Force,, used to produce kinetic used to produce kinetic energyenergy

Page 5: Fluid Mechanics- Pumps

PIST ON PUM PS

PLUNG ER PUM PS

DIAPHRAG M PUM PS

RE C IPRO C A T ING PUM PS

G EAR PUM PS

LOBE PUM PS

SCREW PUM PS

CAM PUM PS

VANE PUM PS

RO T A RY PUM PS

PO S IT IV E D IS PL A C E M E NT PUM PS C E NT RIF UG A L PUM PS

PUM PS

Page 6: Fluid Mechanics- Pumps

RECIPROCATING PUMPSRECIPROCATING PUMPS

Based on two stroke principleBased on two stroke principles:s:

√ √ High pressure, high efficiencyHigh pressure, high efficiency

√ √ Self-primingSelf-priming

XX Small quantity, vibration, physical dimension, Small quantity, vibration, physical dimension, uneven flowuneven flow

Used mainly for handling slurries inUsed mainly for handling slurries in plant processes plant processes and pipeline applicationsand pipeline applications

Page 7: Fluid Mechanics- Pumps

P IS TO N P U M P S

P L U N G E R P U M P S

D IA P H R A G M P U M P S

R E C IP R O C A TIN G P U M P S

P O S ITIV E D IS P L A C E M E N T P U M P S

Two valves and one stuffing boxTwo valves and one stuffing box AA rotating mechanism rotating mechanism for the for the

reciprocating pistonreciprocating piston UUses suction to raise ses suction to raise liquidliquid into into

the chamberthe chamber..

Page 8: Fluid Mechanics- Pumps

The principle of operation is same as that of the piston pump.The principle of operation is same as that of the piston pump. Two ball check valves on each sideTwo ball check valves on each side Low pressure on the upward part, high pressure on the downward Low pressure on the upward part, high pressure on the downward

partpart Used for high pressure applications and can discharge against a Used for high pressure applications and can discharge against a

pressure of 150 MPa or more.pressure of 150 MPa or more.

P IS TO N P U M P S

P L U N G E R P U M P S

D IA P H R A G M P U M P S

R E C IP R O C A TIN G P U M P S

P O S ITIV E D IS P L A C E M E N T P U M P S

Page 9: Fluid Mechanics- Pumps

For handling of corrosive liquids, toxic liquids, For handling of corrosive liquids, toxic liquids, suspensions of abrasive solids Diaphragm pumps suspensions of abrasive solids Diaphragm pumps are used.are used.

The pump is divided into two sections. In one The pump is divided into two sections. In one section of the pump, there is a liquid to be section of the pump, there is a liquid to be pumped and in other another section piston or pumped and in other another section piston or plunger working in oil, which actuates the plunger working in oil, which actuates the diaphragm.diaphragm.

RRod is od is mmoveoved tod to push push and pull and pull the diaphragm the diaphragm.. Can be used to make artificial hearts.Can be used to make artificial hearts.

P IS TO N P U M P S

P L U N G E R P U M P S

D IA P H R A G M P U M P S

R E C IP R O C A TIN G P U M P S

P O S ITIV E D IS P L A C E M E N T P U M P S

Page 10: Fluid Mechanics- Pumps

ROTARY PUMPSROTARY PUMPS Positive displacement typePositive displacement type

High pressure, high efficiencyHigh pressure, high efficiency

Liquids must be free of solidsLiquids must be free of solids

Handle viscous fluidsHandle viscous fluids Used mainly in, oil burners, soaps and Used mainly in, oil burners, soaps and

cosmetics, sugars, syrup, and molasses, cosmetics, sugars, syrup, and molasses, dyes, ink, bleaches, vegetable and dyes, ink, bleaches, vegetable and mineral oilsmineral oils

Page 11: Fluid Mechanics- Pumps

G E A R P U M P S

L O B E P U M P S

S C R E W P U M P S

C A M P U M P S

V A N E P U M P S

R O TA R Y P U M P S

Gears create voids as Gears create voids as they come out they come out of mesh and liquid flows into the of mesh and liquid flows into the cavitiescavities

As the gears come back into mesh, As the gears come back into mesh, the volume is reduced and the liquid the volume is reduced and the liquid is forced out of the discharge portis forced out of the discharge port

Page 12: Fluid Mechanics- Pumps

G E A R P U M P S

L O B E P U M P S

S C R E W P U M P S

C A M P U M P S

V A N E P U M P S

R O TA R Y P U M P S

As the teeth come out of mesh, As the teeth come out of mesh, liquid flows into the pump and liquid flows into the pump and is carried between the teeth is carried between the teeth and the casing to the discharge and the casing to the discharge side of the pump side of the pump

The teeth come back into mesh The teeth come back into mesh and the liquid is forced out the and the liquid is forced out the discharge portdischarge port

Page 13: Fluid Mechanics- Pumps

Fluid is carried between the rotor Fluid is carried between the rotor teeth and the pumping chamber teeth and the pumping chamber

The rotor surfaces create The rotor surfaces create continuous sealingcontinuous sealing

Rotors include bi-wing, tri-lobe, Rotors include bi-wing, tri-lobe, and multi-lobe configurationsand multi-lobe configurations

G E A R P U M P S

L O B E P U M P S

S C R E W P U M P S

C A M P U M P S

V A N E P U M P S

R O TA R Y P U M P S

Page 14: Fluid Mechanics- Pumps

Screw pumps carry fluid in the Screw pumps carry fluid in the spaces between the screw threads.  spaces between the screw threads. 

The fluid is displaced axially as the The fluid is displaced axially as the screws mesh. screws mesh.

G E A R P U M P S

L O B E P U M P S

S C R E W P U M P S

C A M P U M P S

V A N E P U M P S

R O TA R Y P U M P S

Page 15: Fluid Mechanics- Pumps

PPiston slide arm moves iston slide arm moves around inside a slot in the around inside a slot in the casing. casing.

AAn eccentric cam rotates the n eccentric cam rotates the circular plunger (shown in circular plunger (shown in gray) around the edge of the gray) around the edge of the casing, fluid is swirled around casing, fluid is swirled around the edge to the outlet port. the edge to the outlet port.

It is not in use now and is It is not in use now and is mainly of historical curiositymainly of historical curiosity. .

G E A R P U M P S

L O B E P U M P S

S C R E W P U M P S

C A M P U M P S

V A N E P U M P S

R O TA R Y P U M P S

Page 16: Fluid Mechanics- Pumps

G E A R P U M P S

L O B E P U M P S

S C R E W P U M P S

C A M P U M P S

V A N E P U M P S

R O TA R Y P U M P S

TThe vanes are in slots in the rotor. he vanes are in slots in the rotor. RRotor spins, centrifugal force pushes otor spins, centrifugal force pushes

the vanes out to touch the casing, the vanes out to touch the casing, where they trap and propel fluid. where they trap and propel fluid.

Page 17: Fluid Mechanics- Pumps

CENTRIFUGAL PUMPSCENTRIFUGAL PUMPS

WHAT IS CENTRIFUGAL PUMP?WHAT IS CENTRIFUGAL PUMP? WORKING MECHANISM OF A CENTRIFUGAL WORKING MECHANISM OF A CENTRIFUGAL

PUMPPUMP ADVANTEGAES AND DISADVANTAGES OF ADVANTEGAES AND DISADVANTAGES OF

CENTRIFUGAL PUMPSCENTRIFUGAL PUMPS

Page 18: Fluid Mechanics- Pumps

WHAT IS CENTRIFUGAL PUMP?WHAT IS CENTRIFUGAL PUMP?

Convert the mechanical energy into Convert the mechanical energy into hydraulic energy by centrifugal force hydraulic energy by centrifugal force on the liquidon the liquid

Constitute the most common type of Constitute the most common type of pumping machinerypumping machinery

Used to move liquids through a piping Used to move liquids through a piping systemsystem

Has two main components:Has two main components: 1. Stationary componets, casing, 1. Stationary componets, casing,

casing cover and bearingscasing cover and bearings2. Rotating components, impeller and 2. Rotating components, impeller and shaftshaft

Classified into three categories ; Classified into three categories ; Radial Flow, Mixed Flow, Axial FlowRadial Flow, Mixed Flow, Axial Flow

Page 19: Fluid Mechanics- Pumps

WORKING MECHANISM OF A WORKING MECHANISM OF A CENTRIFUGAL PUMPCENTRIFUGAL PUMP

Simplest piece of equipment Simplest piece of equipment in any process plantin any process plant

Energy changes occur by Energy changes occur by virtue of impeller and volutevirtue of impeller and volute

Liquid is fed into the pump at Liquid is fed into the pump at the center of a rotating the center of a rotating impeller and thrown outward impeller and thrown outward by centrifugal forceby centrifugal force

The conversion of kinetic The conversion of kinetic energy into pressure energy energy into pressure energy supplies the pressure supplies the pressure difference between the difference between the suction side and delivery side suction side and delivery side of the pumpof the pump

Liquid flow path inside a centrifugal pump

Page 20: Fluid Mechanics- Pumps

ADVANTAGES OF CENTRIGUGAL ADVANTAGES OF CENTRIGUGAL PUMPSPUMPS

AdvantagesAdvantages

Simple in construction and cheapSimple in construction and cheap Handle liquid with large amounts of solidsHandle liquid with large amounts of solids No metal to metal fitsNo metal to metal fits No valves involved in pump operationNo valves involved in pump operation Maintenance costs are lowerMaintenance costs are lower

Page 21: Fluid Mechanics- Pumps

DISADVANTAGES OF DISADVANTAGES OF CENTRIFUGAL PUMPSCENTRIFUGAL PUMPS

DisadvantagesDisadvantages

Cannot handle highly viscous fluids efficientlyCannot handle highly viscous fluids efficiently Cannot be operated at high headsCannot be operated at high heads Maximum efficiency holds over a narrow range of Maximum efficiency holds over a narrow range of

conditionsconditions

Page 22: Fluid Mechanics- Pumps

PUMPING PROBLEMSPUMPING PROBLEMSCavitation

Reduces the pump capacityReduces the pump capacity

CausesCauses metal removalmetal removal

reduced flowreduced flow

loss in efficiencyloss in efficiency

and noiseand noise

To avoid cavitation To avoid cavitation NPSH

Page 23: Fluid Mechanics- Pumps

POWER AND EFFICIENCY POWER AND EFFICIENCY CALCULATIONSCALCULATIONS

•The power supplied to the pump:

Where m=mass flow rate, kg/s H= total discharge head, N.m/kg =efficiency

…………(1)

Page 24: Fluid Mechanics- Pumps

•The power delivered to the fluid:

……………(2)

•From equations (1) and (2) efficiency:

Page 25: Fluid Mechanics- Pumps

PUMP SELECTIONPUMP SELECTION

The amount of fluidThe amount of fluid

The properties of the fluid The properties of the fluid

Type of power supplyType of power supply

Cost and mechanical efficiency of the pumpCost and mechanical efficiency of the pump

Page 26: Fluid Mechanics- Pumps

CAPACITY

LOW HIGH

GEAR LOBE CENTRIFUGAL

PRESSURE

SMALL OR MODERATE

MODERATEOR HIGH

ROTARY PLUNGER

or

ROTARY PISTON

RECIPROCATING or

RIGID SCREW

HIGHER

Page 27: Fluid Mechanics- Pumps

REFERENCES

1.1. http://en.wikipedia.org/wiki/Pumphttp://en.wikipedia.org/wiki/Pump

2.2. www.cheresources.comwww.cheresources.com

3.3. www.pumpworld.com/contents.htmwww.pumpworld.com/contents.htm

4.4. www.rpi.edu./dept/chem-eng/ www.rpi.edu./dept/chem-eng/ Biotech-Environ/PUMPS/intro.htmlBiotech-Environ/PUMPS/intro.html

Page 28: Fluid Mechanics- Pumps

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