Pump old
Short Description
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Description
PUMP Pump is a mechanical device that converts mechanical power into hydraulic energy. Function of Pump:
Pump enables a liquid to: . Flow from a region region or low pressure pressure to to one of high pressure . Flow from a low level to a higher level . Flow at a faster rate Applications: •
Drainage System
•
Agriculture and Irrigation system
•
ube wells
•
!il pumps
Types of Pump here are two main categories of pump •
Dynamic Pressure Pumps.
•
Positive Displacement Pumps.
Difference between dynamic pressure and positive displacement pump: •
Dynamic pump imparts velocity energy to the fluid" which is converted to pressure energy upon e#iting the pump pump casing
•
Positive displacement pump moves a fi#ed volume of fluid within the pump casing by applying a force to moveable boundaries containing the fluid volume.
Positive Displacement
Dynamic Pressure
Classification of Pumps P$MP Dynamic Pressure Pump
Positi#e Displacement
entri!ug al Reciprocatin g
Rotary Axial fow Mixed fow
Gear
"urbine
Piston
Lobe
Diaphrag m
Sliding Vane
Plunger
Screw
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
•
Initial and maintenance cost
Parameters for the Selection of Pump Parameter
Centrifugal Pumps
Reciprocating Pumps
Rotary Pumps
Optimum 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
%,"""# 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
Maimum Pressure
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" steam turbine or gasoline engine to energy within the liquid being pumped
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
+.
Pump Shaft
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
Thickness of the impeller
Diameter o!
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
Radial vanes
Backward vanes
Forward vanes
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
Impeller
Suction
Components of Centrifugal Pump (.
)ri*e Mechanism provides energy to the impeller. It can be electric motor "steam engine or gasoline engine.
+.
Pump Shaft transmits power from prime mover to the pump impeller.
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. It produces same flow rate but higher head .
Pump Configuration '. Parallel Pump wo or more pumps are connected to a common discharge line" and share the same suction conditions It produces same head but high flow rate.
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 N2 •
orsepower changes as the cube of a change in speed or diameter
W α N3
Performance Characteristic Cur*e •
Predict the performance of pump when the pump is wor%ing under different flow rate.
Terminologies Use" in Pump ,ea" is defined as height of water column. • -&
,ea" is the height at which a pump can raise water up
Terminologies 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 on.
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
.
by the pump when fluid moves through it
!osses an" fficiencies 1. • ,y"raulic fficiency are the losses the occur between the suction and the delivery ends of a pump .
Pump2 s Total Head / H 0 h
Euler Head / H e 0
ydraulic efficiency varies from 0.1 to 0.2.
'. $olumetric efficiency is the ratio of the actual discharge to the total
discharge.
Q v
Q
Q
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.
!osses an" fficiencies +. -*erall fficiency is the ratio of the total head developed by a pump to the total power input to the shaft . ζ m
=
Power in to the impeller Power at the shaft
ange of overall efficiency is between 0.6' to 0.71.
o
m
v
h
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. Total "ifferential hea" 4 static hea" "ifference 5 frictional hea" losses
Si3ing of Pump •
Static ,ea" )ifference
Difference in head between the discharge static head and the suction static head. Static hea" "ifference 4 "ischarge static hea" 6 suction static hea"
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,
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