10-Centrifugal Pumps Construction 1
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Transcript of 10-Centrifugal Pumps Construction 1
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OF CENTRIFUCONSTRUCTIONGAL PUMPS
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Construction of Centrifugal Pumps
Casing
Casing generally are two types:
I. Volute casings for a higher head.
II. Circular casings for low head and high
capacity.
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Construction of Centrifugal Pumps
CasingVolute casings:
A volute is a curved funnel
increasing in area to the
discharge port.
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Construction of Centrifugal Pumps
CasingVolute casings:
Running volute-style pumps
at a lower capacity than the
manufacturer recommendscan put lateral stress on the
shaft of the pump,
increasing wear-and-tear
on the seals and bearings,and on the shaft itself.
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Construction of Centrifugal Pumps
CasingVolute casings:
Double- volute casings are
used when the radial
thrusts become significantat reduced capacities.
the main purposes of a
volute casing is to help
balance the hydraulicpressure on the shaft of the
pump at the manufacturer's
recommended capacity .
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Construction of Centrifugal Pumps
CasingCircular casings:
have stationary diffusion vanes surrounding the impeller
periphery that convert velocity energy to pressure energy.
Solid casing is one casting or fabricated piece.
Split casing consists of two or more parts are fastened together.
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Construction of Centrifugal Pumps
CasingCircular casings:
Split casing
Horizontally split or axially split casing.
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Construction of Centrifugal Pumps
CasingCircular casings:
Split casing
Vertically split or radially split casing.
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Construction of Centrifugal Pumps
Casing
Shaft
weight
Sha
ftdeflection
Cost=
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Construction of Centrifugal Pumps
CasingThe ideal design would be one which reduces radial thrust
to an acceptable level.
How?
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Construction of Centrifugal Pumps
CasingSome pump casings use a split volute design instead of a
double volute.
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Construction of Centrifugal Pumps
Casing
Some pump casings use a split volute design instead of
a double volute.
Diffuser pump casings:
The liquid leaves the diffuser at
a higher pressure than it leaves
the impeller, then enters the
casing annulus and finally
leaves at the discharge branch.
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Construction of Centrifugal Pumps
Casing
Diffusers are frequently used in
multi-stage pumps and are
more efficient than volute typesof casing.
Diffuser pump casings:
However, diffuser designs are
more costly than volute designs
and therefore single-stagediffuser pumps are not used as
often as volute types because
of the expense.
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
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Diffuser
Construction of Centrifugal Pumps
CasingMulti-stage pumps:
Diffuser
Impeller
1. Guides the liquid flow from one
impeller to the next.
2. acts in a similar manner to a volute
by converting velocity energy (kinetic
energy) into pressure energy.
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
LP
LP
HP
HP
LP HP HP LP
LP
LP
Normal thrust
on rotor
Normal thrust
on rotor
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
LP
LP
HP
HP
LP HP HP LP
Normal thrust
on rotor
Normal thrust
on rotor
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
LP
LP
HP
HP
LP HP HP LP
Normal thrust
on rotor
Normal thrust
on rotor
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
LP
LP
HP
HP
LP HP HP LP
Normal thrust
on rotor
Normal thrust
on rotor
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
LP
LP
HP
HP
LP HP HP LP
Normal thrust
on rotor
Normal thrust
on rotor
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
LP
LP
HP
HP
LP HP HP LP
Normal thrust
on rotor
Normal thrust
on rotor
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
LP
LP
HP
HP
LP HP HP LP
Normal thrust
on rotor
Normal thrust
on rotor
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
LP
LP
HP
HP
LP HP HP LP
Normal thrust
on rotor
Normal thrust
on rotor
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
LP
LP
HP
HP
LP HP HP LP
Normal thrust
on rotor
Normal thrust
on rotor
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
LP
LP
HP
HP
LP HP HP LP
Normal thrust
on rotor
Normal thrust
on rotor
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
LP
LP
HP
HP
LP HP HP LP
Normal thrust
on rotor
Normal thrust
on rotor
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Construction of Centrifugal Pumps
CasingMulti-stage pumps:
LP
LP
HP
HP
LP HP HP LP
Normal thrust
on rotor
Normal thrust
on rotor
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Construction of Centrifugal Pumps
CasingSuction and Discharge nozzle:
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Construction of Centrifugal Pumps
CasingSuction and Discharge nozzle:
End suction/Top discharge:
1) Always an overhung type.2) Typically has lower NPSHR.
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Construction of Centrifugal Pumps
CasingSuction and Discharge nozzle:
Top suction/Top discharge:
1) Always a radially split case pump.2) It can be either an overhung type
or between bearing type..
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Construction of Centrifugal Pumps
Casing
Side suction/Side discharge:
This pump can have either an axially orradially split case type.
Suction and Discharge nozzle:
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Construction of Centrifugal Pumps
CasingSeal Chamber and Stuffing Box:
If sealing is by mechanical seal, the chamber is referred to as a
Seal Chamber.
If sealing is by packing, the chamber is referred to as a StuffingBox.
They either integral with or
separate from the pump
case housing that forms theregion between the shaft
and casing where sealing
media are installed.
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Construction of Centrifugal Pumps
CasingSeal Chamber and Stuffing Box:
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Construction of Centrifugal Pumps
CasingSeal Chamber and Stuffing Box:
Throat
bushing
Throttlebushing
GlandInternal circulating device
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Construction of Centrifugal Pumps
Bearing housing