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UVEES 1
Centrifugal PumpsTraining Program @ Petronet LNG
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PUMP
A pump is a machine that imparts
energy to the liquid in it to flow or rise
to a higher level / pressure or both.
PUMPA machine used for the
purpose of transferring
quantities of liquids from
one place to another.
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UVEES 3
PUMPS
POSITIVE
DISPLACEMENTROTODYNAMIC
Energy is imparted to the
fixed volume of liquid.
RECOPROCATING:
PISTON / PLUNGER
Kinetic energy of a rotor is
converted in to fluid energy
ROTARY:
LOBE, GEAR, VANE, PISTON
Types of Pumps
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UVEES 4
Positive
Displacement
Pumps
a. Reciprocating piston or
plunger
b.External gear
c. Double screw
d.Sliding vane
e.Three lobef. Twin circumferential pis
ton
g. Peristaltic .
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UVEES 5
Rotodynamic Pump Theory
The (rotational) kinetic energy of impeller istransferred to liquid in the casing of the pump
by dynamic action.
The velocity of the flow is reduced to convert it
in to potential energy and/or pressure energy.
The Bernoulli's principle says so.
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UVEES 6
Action of moving Blade
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Kinetic EnergyPotential
& Pressure Energy
This is achieved by thevolute casing ordiffuser vanes in which
cross sectional area ofthe casing is graduallyincreased. This willdecrease velocity of flow
(KE) to result inincrease in pressure.
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UVEES 8
Simplify? . .
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UVEES 10
Working of RDP (contd.)
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CENTRIFUGAL
PUMPS
IMPELLERS AXIS CASINGS STAGES
RADIAL FLOWCLOSED
AXIAL FLOW
VERTICAL
HOROZONTALVOLUTE
SINGLE
MULTI
SEMI OPEN
MIXED FLOW OPEN
DIFFUSER
(IN VERTICAL
TURBINE PUMP)
Classification ofRotodynamic Pump
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UVEES 12
Centrifugal Pumps
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Multistage Pumps
Horizontal Centrifugal &
Vertical Turbine Pumps
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Vertical Turbine Pumps
Generally mixed flow type, Single stage
or Multi stage types.
Other components; viz. entry bell,
bearings, couplings and seals.
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UVEES 15
Cryogenic Pumps
Cryogenic pumps are
used for handling liquids attemperatures as low as -160C (-320F). Topsuction pump design has
become a standard in theindustry for handling fluidswhich are near or atboiling point without vapor
binding. such as LiquefiedOxygen, Nitrogen, NaturalGas, etc..
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UVEES 16
Cryogenic Pumps (contd.)
Design considerations for cryogenic pumps include
special metallurgical considerations due to lowtemperatures and flammability of liquefied gases
such as LNG, liquid oxygen, thermal expansion and
contraction and material behavior at cryogenic
temperatures, and extremely low NPSH.
Impellers may be either of the semi-open or closed
design and are keyed to the shaft. Both single and
multi-stage cryogenic pumps can be designed toincorporate an inducer for low NPSH applications.
Inducers are individually sized for each application.
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UVEES 17
Cryogenic Pumps (contd.)
Shaft sealing is provided by a precision labyrinth
seal which operates at the pump suction pressure.
Thermocouples are used to detect and monitor theliquid level in the pump column. This safety featureensures that the labyrinth seals operate in vaporphase and icing at the support plate is eliminated.
In one of design, easily replaceable cartridgeassemblies are mounted in the bearing frame above
the top mounting plate. This configuration providesgreater support for the pump shaft and eliminatesthe reliance of the drive motor's bearings.
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UVEES 18
Selection of Pump
.. is very important decision making.
Important Parameters considered are . . .
Head and Flow : The Duty or Operation combo
Type of liquid; Clear, Contaminated, Corrosive,
Viscous, Volatile, etc/
Input Power & Efficiency
NPSH Required
Maintenance requirement
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Estimation of Flow and Head +
The average flow/capacity requirement ofprocess most of the time and range of
variation.
The pressure sufficient to overcome total
dynamic head for the flow required.
NPSH available at suction side.
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Total Dynamic Head (TDH)=
Static Lift + Static Height + Pressure
of Upstream System connected +Friction Losses + Other Losses
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Pump Characteristic Curves
Interpretation of CC
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Interpretation of CC
As flow increases the
head developed
decreases.
Power consumption
increases with increase
in flow NPSHr increases with
increase inflow
There exist a best
efficiency point, to betargeted for fixing duty
point near it
C it ti
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UVEES 23
Cavitation
Low pressure at the suction side of a pump
can encounter the fluid to start boiling with
reduced efficiency and cavitation damage
of the pump as a result. Boiling starts when the
pressure in the liquid is reduced to the vaporpressure of the fluid at the actual temperature.
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UVEES 25
Model Modification
Pumps are selected for its operation atbest efficiency point most of the time. If the
duty point is not matching with BEP, what
to do?
Pump affinity laws can help us in
necessary modification so that DP & BEP
for the modification match as far aspossible.
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Affinity LawsThe affinity laws express the mathematical relationship betweenthe several variables involved in pump performance. They apply to
all types of centrifugal and axial flow pumps. They are as follows:
2. With speed
N held
constant:
So by changing the diameter of impeller or rotational speed onecan bring DP and BEP nearer. Since it is not impractical to change
the speed, trimming of the impeller is done. Refer the
Interpretation of CC Slide
1. With impeller
diameter D held
constant:
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Material of Construction
of Body - Impeller - Seals
Mainly made of Cast Iron or Steel. Stainless
Steel is used for corrosive liquids or food &
pharmaceutical application.
Special Material for reactive liquids: SpecialMetals (Alloys) e.g. Bronze, Hastelloy,
Carpenter 20 etc. or Nonmetals (Polymers) like
PVDF, PP etc.
Lined (coated internally) for harsh liquids
reducing cost of the special material, e.g. EPDM
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Static Sealing Material
Gaskets and O-ringsEPDM
VITON
BUNA
Natural Rubber
Silicon Rubber
Pump Standards
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Pump StandardsSome commonly used centrifugal pumps standards;
ANSI/API 610-1995 - Centrifugal Pumps for General Refinery Service -Covers the minimum requirements for centrifugal pumps, including pumps
running in reverse as hydraulic power recovery turbines, for use inpetroleum, heavy duty chemicals, and gas industry services. The pumptypes covered by this standard can be broadly classified as overhung,between bearings, and vertically suspended.
DIN EN ISO 5199 - Technical specifications for centrifugal pumps
ASME B73.1-2001 - Specification for Horizontal End Suction CentrifugalPumps for Chemical Process - This standard covers centrifugal pumps of
horizontal, end suction single stage, centerline discharge design. ThisStandard includes dimensional interchangeability requirements and certaindesign features to facilitate installation and maintenance. It is the intent ofthis Standard that pumps of the same standard dimension designation fromall sources of supply shall be interchangeable with respect to mountingdimensions, size and location of suction and discharge nozzles, inputshafts, baseplates, and foundation bolt holes
ASME B73.2-2003 - Specifications for Vertical In-Line Centrifugal Pumpsfor Chemical Process
BS 5257:1975 - Specification for horizontal end-suction centrifugal pumps(16 bar) - Principal dimensions and nominal duty point. Dimensions for sealcavities and base plate installations.
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UVEES 30
Q & A
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