PUMP
PUMP
Pump
Pump
is a mechanical device that converts mechanical power into is a mechanical device that converts mechanical power into hydraulichydraulic energy.energy.
Function of Pump: Function of Pump:
Pump enables a liquid to: Pump enables a liquid to: .
. Flow from Flow from a ra region or egion or low prelow pressure tssure to one o one of high of high pressurepressure .
. Flow Flow from from a a low low level level to a to a higher higher levellevel .
. Flow Flow at at a a faster faster raterate
Applications: Applications:
•
• Drainage SystemDrainage System •
• Agriculture and Irrigation systemAgriculture and Irrigation system •
• ube wellsube wells •
Types of Pump
Types of Pump
here are two main categories of
here are two main categories of pumppump
•
• Dynamic Dynamic Pressure Pressure Pumps.Pumps. •
• Positive Displacement Pumps.Positive Displacement Pumps.
Difference between dynamic pressure and positive
Difference between dynamic pressure and positive displacement pump:displacement pump:
•
• Dynamic pump imparts velocity energy to the fluid" which is converted to Dynamic pump imparts velocity energy to the fluid" which is converted to
pressure energy
pressure energy upon e#iting the pumupon e#iting the pump casingp casing
•
• Positive displacement pump moves a fi#ed volume of fluid within thePositive displacement pump moves a fi#ed volume of fluid within the
pump
pump casing casing by by applying applying a a force force to to moveable moveable boundaries boundaries containing containing thethe fluid volume fluid volume
.
.
Positive Displacement Positive Displacement Dynamic Pressure Dynamic PressureClassification of Pumps
Classification of Pumps
Diaphrag Diaphrag m m Piston Piston Plunger Plunger Reciprocatin Reciprocatin g g Rotary Rotary Mixed Mixed fowfow GearGear
Lobe Lobe Sliding Sliding Vane Vane Screw Screw Axial fow Axial fow entri!ug entri!ug al al Dynamic Dynamic Pressure Pressure Pump Pump "urbine "urbine Positi#e Positi#e Displacement Displacement
P$MP
P$MP
Parameters for the Selection of Pump
Some of the parameters that decide the selection of pump are:
•
Pressure and capacity of liquid being handled
•Speed of rotation and power requirement
•
Properties such as viscosity" corrosiveness etc of fluid
•Availability of space for positioning of pump
Parameters for the Selection of Pump
Parameter Centrifugal Pumps Reciprocating Pumps Rotary PumpsOptimum Flow and Pressure Applications Medium/High Capacity, Low/Medium Pressure Low Capacity, High Pressure Low/Medium Capacity, Low/Medium Pressure Maimum Flow Rate !"","""# $PM !","""# $PM !","""# $PM
Maimum Pressure %,"""# P&' !"","""# P&' (,"""# P&'
&pace
Considerations
Re)uires Less &pace
Re)uires More &pace Re)uires Less &pace Costs Lower 'nitial
Lower Maintenance Higher Power Higher 'nitial Higher Maintenance Lower Power Lower 'nitial Lower Maintenance Lower Power
Centrifugal Pumps
Centrifugal Pump
can be defined as a mechanical device used to transfer liquid• $onverts the energy provided by a prime mover" such as an electric motor"
Working of Centrifugal Pump
$entrifugal pumps wor%s on principle of centrifugal force.
• It has a rotating impeller also %nown as a blade that is immersed in the
liquid.
• &iquid enters the pump near the a#is of the impeller and the rotating
impeller sweeps the liquid out toward the ends of the impeller blades at high pressure
%
Components of Centrifugal Pump
'. Impeller
(. $asing
). Drive *echanism
Components of Centrifugal Pump
1. mpeller
is a rotating component of a centrifugal pump which transfers energy from the motor that drives the pump to the fluid being pumped.•. Thicker the impeller , *ore fluid •. !arger the "iameter , *ore pressure
•. ncrease the spee" , *ore water and pressure
&
'ye o! the (mpeller) *ater'ntrance
Diameter o!
Thickness
Components of Pump
Impeller is classified into three types depending upon impeller vanes
• For#ar" $anes: -anes are in the direction of motion of impeller • %ack#ar" $anes: -anes are opposite to the direction of motion of
impeller
• &a"ial $anes: -anes are straight
Components of Centrifugal Pump
'. Casing
is a stationary part of the pump that receives the fluid being pump by the impeller$asing generally are two types:
•. $olute Casing:
It is used for a higher head. A volute is a curved funnel increasing in area to the discharge port.
•. Circular Casing:
It is used for low head and high capacity. It has stationary diffusion vanes surrounding the impeller periphery that convert velocity energy to
pressure energy. Volute
Suction Impeller
Components of Centrifugal Pump
(.
)ri*e Mechanism
provides energy to the impeller. It can be electric motor "steam engine or gasoline engine.Pump Configuration
Pump may be connected in series or parallel.
1. Series Pump
Pump is said to be connected in series if the discharge of one pump is connected to the suction side of a second pump.
Pump Configuration
'. Parallel Pump
wo or more pumps are connected to a common discharge line" and share the same suction conditions
Affinity !a#
Affinity !a# of centrifugal pump indicates the influence on flow rate" head and power consumption of a pump due to:
change in impeller spee" change in impeller "iameter
• Flow changes directly as a change in speed or diameter
Q
α
N
• ead changes as the square of a change in speed or diameter
H
α
N
2• orsepower changes as the cube of a change in speed or diameter
Performance Characteristic Cur*e
• Predict the performance of pump when the pump is wor%ing under
Terminologies Use" in Pump
,ea"
is defined as height of water column.-&
,ea"
is the height at which a pump can raise water upTerminologies Use" in Pump
• Static Suction ,ea" is head on the suction side" with pump off.
• Static )ischarge ,ea" is head on discharge side of pump" with the pump
off.
• )ynamic Suction ,ea" is head on suction side of pump with pump on. • )ynamic )ischarge ,ea" is head on discharge side of pump with pump
Terminologies Use" in Pump
• Pressure ,ea" is measure of fluid/s potential energy
.
• $elocity ,ea" is measure of fluid/s %inetic energy.
• Friction ,ea" is measure of energy loss that heats fluid
.
• et Positi*e Suction ,ea" /PS,0 defines the pressure required at the
suction of a pump to prevent cavitation
• Manometric ,ea" is defined as the change in total energy head produced
!osses an" fficiencies
1. ,y"raulic fficiency
are the losses the occur between the suction and the delivery ends of a pump.ydraulic efficiency varies from 0.1 to 0.2.
'. $olumetric efficiency
is the ratio of the actual discharge to the total discharge.3 4 Amount of discharge 53 4 Amount of lea%age.
It/s value lies between 0.26 and 0.27
(. Mechanical efficiency
is the ratio of the actual power input to the impeller and the power given to the shaft.ζm
P 4 otal power input to the shaft 5 P 4 *echanical losses
It/s value lies between 289 , 279.
• 0 / 0 / 2 e h H Head Euler H Head Total s Pump Q Q Q v
!osses an" fficiencies
+. -*erall fficiency
is the ratio of the total head developed by a pump to the total power input to the shaft.
ange of overall efficiency is between 0.6' to 0.71. shaft the at Power impeller the to in Power m = ζ h v m o
Si3ing of Pump
o si;e a pump" you must define
:
• Flow rate of liquid the pump is required to deliver
• otal differential head the pump must generate to deliver the required flow
rate
•
Flo# &ate
Determined by the process in which the pump is installed. Defined by the mass and energy balance of the process.
•
Total )ifferential ,ea"
he total differential head is made up of ( components.
Si3ing of Pump
•Static ,ea" )ifference
Difference in head between the discharge static head and the suction static head
.
Si3ing of Pump
•Suction Static ,ea"
he suction static head is sum of the gas pressure at the surface of the liquid in the suction vessel and the difference in elevation between the surface of the liquid in the suction vessel and the center line of the pump.
Suction static hea" 4 Suction *essel gas pressure hea" 5 ele*ation of suction *essel li7ui" surface 6 ele*ation of pump center line
Si3ing of Pump
•)ischarge Static ,ea"
)ischarge static hea" 4 )ischarge *essel gas pressure hea" 5 ele*ation of
"ischarge pipe outlet 6 ele*ation of pump center line
he discharge pipe outlet may be above the surface of the liquid in the discharge vessel or it may be submerged as shown in these two diagrams.
Si3ing of Pump
•Frictional ,ea" !osses
he frictional head losses are usually calculated from the Darcy,<eisbach equation using friction factors and fittings factors to calculate the pressure loss in pipes and fittings.
Frictional hea" losses 4 frictional losses in suction piping system 5 frictional losses in "ischarge piping system
Si3ing of Pump
•et Positi*e Suction ,ea" A*aila8le
=et positive suction head available >=PSa? must e#ceed the net positive suction head required >=PSr? for that particular pump.
=PSr is given by the pump manufacturer
et positi*e suction hea" a*aila8le 4 a8solute pressure hea" at the pump suction 6 li7ui" *apor pressure hea"
•
Pump Po#er
Pumps are usually driven by electric motors" diesel engines or steam turbines. Determining the power required is essential to si;ing the pump driver .
Pump po#er 4 flo# rate 9 total "ifferential hea" 9 li7ui" "ensity 9 acceleration "ue to gra*ity pump efficiency
Si3ing of Pump
9ample:
<ater Flow ate:)0000 %g@hr <ater emperature:(0$
<ater Density :227 %g@m)
-apor Pressure :0.0()bara <ater -iscosity:'cP
Pump efficiency is 609
Calculation:
Pump Pro8lems an" Trou8leshooting
•
Ca*itation
$avitation occurs when the pressure falls below the vapor pressure of the liquid at a given temperature" small bubbles of vapor are formed.
Pump Pro8lems an" Trou8leshooting
Pump Pro8lems an" Trou8leshooting
Pump Pro8lems an" Trou8leshooting
•
Priming
Priming is the process of filling the impeller of centrifugal pump with water
.
• equired when there is a first start up.
• Pump casing becomes filled with vapors or gases" the pump impeller
