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What is a Pump ?
A pump is a device that moves fluids or
sometimes slurries, by mechanical action.
Pumps can be classified into three major groups
according to the method they use to move the
fluid:-
direct lift, displacement, andgravity pumps.
Pumps operate by some mechanism (typically
reciprocating or rotary), and consume energy to
perform mechanical work by moving the fluid.
1
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Gravity pumps
Gravity pumps include thesyphon and
Heron's fountain
and there also important qanatorfoggara
systems that simply use downhill flow to
take water from far-underground aquifers in
high areas to consumers at lower elevations.
The hydraulic ram is also sometimes called
a gravity pump.
2
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Pumps
Centrifugal- Single StageMultistage AxialMixed Flow
Positive Displacement-
Gear Type
Screw Type
Reciprocating Type.
Jet Pump
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Basic
A pump transfers liquids from a region of LOWpressure to a region of HIGH pressure.
A pump is a device that moves fluids , orsometimes slurries, by mechanical action.
Pumps can be classified into three major groups
according to the method they use to move thefluid: direct lift, displacement, andgravity pumps.
Pumps operate by some mechanism (typicallyreciprocating or rotary), and consume energy toperform mechanical work by moving the fluid.
Pumps operate via many energy sources,including manual operation, electricity, an engineof some type, or wind power.
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Positive displacement pump
A positive displacement pump makes a fluid
move by trapping a fixed amount, and forcing (displacing) that trapped volume into
the discharge pipe.
Some positive displacement pumps use an
expanding cavity on the suction side and adecreasing cavity on the discharge side.
Liquid flows into the pump as the cavity on thesuction side expands and the liquid flows out of
the discharge as the cavity collapses. The volume is constant through each cycle of
operation.
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Positive displacement pump behaviour and safety
Positive displacement pumps, can produce the same flow at a
given speed (RPM) no matter what the discharge pressure.
Thus, positive displacement pumps are constant f low
machines.
A positive displacement pump must not operate against a
closed valve on the discharge side.
A positive displacement pump operating against a closed
discharge valve continues to produce flow and the raise the
pressure in the discharge line increases until the line bursts.
A safety valve on the discharge side of the positive
displacement pump is therefore necessary. The internal valve
is usually only used as a safety precaution. An external relief
valve in the discharge line, with a return line back to the
suction line or supply tank provides increased safety.
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Positive displacement types
A positive displacement pump can be further
classified according to the mechanism used to
move the fluid:
Rotary-type positive displacement:
internal gear, screw, flexible vane or sliding
vane, helical twisted roots or liquid ring
vacuum pumps
Reciprocating-type positive displacement:
piston or diaphragm pumps
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Rotary positive displacement pumps
Rotary pumps move fluid using a rotating mechanism that
creates a vacuum that captures and draws in the liquid.
Advantages: Rotary pumps are very efficientbecause they
naturally remove air from the lines, eliminating the need to
bleed the air from the lines manually.
Drawbacks: The pump demands very close clearances
between the rotating pump and the outer edge, making it
rotate at a slow, steady speed.
If rotary pumps are operated at high speeds, the fluidscause erosion, which eventually causes enlarged
clearances that liquid can pass through, which reduces
efficiency.
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Piston and Plunger Pump
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Positive Displacement Lobe Pump
11
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Scroll Pump
The red casing is stationary. The black spiral
revolves in the casing to draw fluid andcompress it.
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Twin Screw Pump
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Gear Pump
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Sliding Vanes Eccentric Rotation
15
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Centrifugal Pump with backward vanes.(The
vanes can be Radial or Forward also)
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Velocity DiagramsRadial, Backward & Forward curved vanes
17
RADIAL
FORWARDBACKWARD
RELATIVE VELOCITY
TIP VELOCITY
RESULTANT
VELOCITY
FORWARD BLADES GIVE HIGHEST VELOCITY
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Closed impellar
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Open Impeller - Non Clogging (For slurry)
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Centrifugal Pump Note the expanding Volute
20
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Axial Pump (Generally they are mixed flow)In pure axial pump the Motor has to be in the pipe.
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Axial Flow Pump Twisted blades
22
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Jet Pump
Works on Bernoullis Principle.
As velocity increases, the pressure falls.
Total energy remains constant.
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Boiler Feed Pump
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Centrifugal Pump
Centrifugal pumps are used to transport fluids by the
conversion of rotational kinetic energy to thehydrodynamic energy of the fluid flow.
The rotational energy typically comes from an engine
or electric motor.
The fluid enters the pump impeller along or near to the
rotating axis and is accelerated by the impeller,
flowing radially outward into a diffuser or volute
chamber (casing), from where it exits.
The reverse function of the centrifugal pump is a water
turbine converting potential energy of water pressure
into mechanical rotational energy. 25
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Multistage centrifugal pumps
A centrifugal pump containing two or more impellers is
called a multistage centrifugal pump. The impellers may be
mounted on the same shaft or on different shafts.
For higher pressures at the outlet, impellers can be connected
in series.
For higher flow output impellers can be connected in
parallel.
A common application of the multistage centrifugal pump is
the boiler feed water pump.
All energy transferred to the fluid is derived from the
mechanical energy driving the impeller.
This can be measured at isentropic compression, resulting in
a slight temperature increase (in addition to the pressure
increase).26
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Power Input to a PUMP
Pi = Q H/
where: (SI Units )
Pi is the input power required (W)
is the fluid density (kg/m3)
is the standard acceleration of gravity (9.8 m/s2)
H is the Head added to the flow (m)
Q is the flow rate (m3/s)
is the efficiency of the pump plant as a decimal.
27
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Illustration
If we consider water as the fluid,
= 1000 Kg/M3; g = 9.81 M/Sec 2; Q = 1 M3 / Second ; H = 10 Meters.
= 0.85 (Motor + Pump)
Then Power required in watts =1000 x 9.81 x 1 x 10 / 0.85
= 115411.76 Watts or
= 115.41 KW
28
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29
BFP - 210 MW (200 KHI)
p 1000 Kg/M3
g 9.81Q 430 m3/Hr
Q 0.119 m3/sec
H 1836 Metersn-Motor 0.75
n-Pump 0.75
n-Composit 0.5625
Watts 3824592
KW 3825
Actual Motor Rating = 4000 KW
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The head added by the pump (H) is a sum
of
the static lift,
the head loss due to friction and
any losses due to valves or pipe bends all
expressed in metres of fluid.
The value for the pump efficiency, , may be
stated for the pump itself or as a combined
efficiency of the pump and motor system.
30
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Difficulties faced in centrifugal pumps:
Cavitationthe net positive suction head (NPSH) of
the system is too low for the selected pump Wear of the Impellercan be worsened by
suspended solids
Corrosion inside the pump caused by the fluid
properties
Overheating due to low flow.(Churning)
Leakage along rotating shaft
Lack of primecentrifugal pumps must be filled
(with the fluid to be pumped) in order to operate
31
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Note how neck rings prevent recirculation 32
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33
Centrifugal pumps contain rotating impellers
within stationary pump casings.
To allow the impeller to rotate freely withinthe pump casing, a small clearance is designed
to be maintained between the impeller and the
pump casing. To maximize the efficiency of a centrifugal
pump, it is necessary to minimize the amount of
liquid leaking through this clearance from thehigh pressure or discharge side of the pump
back to the low pressure or suction side.
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34
Some wear or erosion will occur at the
point,
where the impeller and the pump casing
nearly come into contact.
This wear is due to the erosion causedby liquid leaking through this tight
clearance and other causes.
As wear occurs,
the clearances become larger and the
rate of leakage increases.
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To minimize the cost of pump maintenance, centrifugal
pumps are designed with wearing rings.
Wearing rings are replaceable rings that are attached to
the impeller and/or the pump casing to allow a small
running clearance between the impeller and the pump
casing
without causing wear of the actual impeller or pumpcasing material.
These wearing rings are designed to be replaced
periodically during the life of a pump and
prevent the more costly replacement of the impeller or
the casing.
35
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36
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Axial-flow pump
An axial-flow pump, is a pump that essentially
consists of a propeller (an axial impeller) in a pipe.The propeller can be driven directly by a sealed motor
in the pipe or by electric motor or petrol/diesel engines
mounted to the pipe from the outside or by a right-
angle drive shaft that pierces the pipe.
Fluid particles, in course of their flow through the
pump, do not change theirradiallocations since the
change in Diameter at the entry (called 'suction') andthe exit (called 'discharge') of the pump is very small.
Hence the name "axial" pump.
There is no radial movement of the fluid.37
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Pump specific speed
Low-specific speed radial flow impellers develop
hydraulic head through centrifugal force.Pumps of higher specific speeds develop head partly by
centrifugal force and partly by axial force.
An axial flow or propeller pump with a specific speed
of 10,000 or greater generates its head exclusively
through axial forces.
Radial impellers are generally low flow/high head
designs whereas axial flow impellers are high flow/low head
designs.
38
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Centrifugal pump impellers have specific speed
values ranging from 500 to 10,000 (English units),
Radial flow pumps at 500-4000,Mixed flow at 2000-8000 and
Axial flow pumps at 7000-20,000.
Values of specific speed less than 500 areassociated with positive displacement pumps.
As the specific speed increases, the ratio of the
impeller outlet diameter to the inlet or eye
diameter decreases.
This ratio becomes 1.0 for a true axial flow
impeller.
39
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Specific Speed-Metric System
Ns = n (Q)1/2 / (g H)3/4
where:
Ns- is specific speed (unitless)
N - is pump rotational speed (radians per
second)
Q - is flow rate (m/s) at the point of best
efficiency.
H - is total head (meters) per stage at the point
of best efficiency
g - is acceleration due to gravity (m/s)40
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Selecting between Centrifugal or Positive
Displacement Pumps
Flow Rate and Pressure Head
The Centrifugal Pump has varying flow depending on the system
pressure or head
The Positive Displacement Pump has a constant flow regardless of the
system pressure or head..
Capacity and Viscosity
In the Centrifugal Pump the flow is reduced when the viscosity is
increased
In the Positive Displacement Pump the flow is increased when
viscosity is increased Liquids with high viscosity fill the clearances of a Positive
Displacement Pump causing a higher volumetric efficiency and a
Positive Displacement Pump is better for high viscosity applications.
A Centrifugal Pump becomes very inefficient at even modest viscosity.41
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Mechanical Efficiency
Changing the system pressure or head has little or no
effect on the flow rate in the Positive DisplacementPump
Changing the system pressure or head has a dramatic
effect on the flow rate in the Centrifugal Pump
Net Positive Suction Head - NPSH
In a Centrifugal Pump, NPSH varies as a function of
flow determined by pressure
In a Positive Displacement Pump, NPSH varies as afunction of flow determined by speed.
Reducing the speed of the Positive Displacement Pump,
reduces the NPSH42
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Losses in Pumps & Efficiency
Internal losses
hydraulic losses - disk friction in the impeller, loss due torapid change in direction an velocities through the pump
volumetric losses - internal recirculation at wear rings and
bushes
External losses
mechanical losses - friction in seals and bearings .
The efficiency of the pump at the designed point is
normally maximum and is called the Best Efficiency Point
- BEP
It is possible to operate the pump at other points than BEP,
but the efficiency of the pump will always be lower than
BEP. 43
B Effi i P i
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Best Efficiency Point
44
C t if l P P t
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Centrifugal Pump Parts
45
M lti St B F P
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Multi-Stage B.F.P.
46
B i M h i l S l
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Basic Mechanical Seal
47
WATER PUMPS IN POWER STATION
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WATER PUMPS IN POWER STATION
48
Hi h P BFP S l k
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High Pressure BFP Sulzer make
49
C d t E t ti P
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Condensate Extraction Pump
50
S li f CEP
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Sealing for CEP
The CEP has negative suction.
Hence any opening will result in air ingress fromthe atmosphere.
So, the glands of the pump and suction side valves
are provided with sealing water tapped from the
pump discharge.
Even the glands of condenser level indicator
isolating valves must be made leakproof.
If there is air ingress in level indicator, correctlevel indication is not possible.
51
P t f CEP
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Parts of CEP
52
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53
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54
Balancing Scheme
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Balancing Scheme
55
Balancing Disc
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Balancing Disc
56
Gland packing Stuffing Box
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Gland packing Stuffing Box
57
Mechanical Seal
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Mechanical Seal
58
BOILER FEED WATER PUMP
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BOILER FEED WATER PUMP
Boiler feed pump is the major power consumer
among all power consuming equipment in the
power plant. BFP may constitute about 25% of the
total auxiliary power consumption. (4% of Power
Generated)
BFP Main Parameters for 210 MW unit
Model Speed
RPM
Disch. head
mWC
Capacity
TPH
Motor
Power kW
200 KHI 4320 1834.6 430 4000
FK 6D 30 5050 2104 398 350059
BFP LAYOUT
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BFP LAYOUT
60
B F P Protections
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B.F.P.- Protections
NPSH (Minimum pressure at suction to
avoid flashing) Minimum Flow Valve (Churning)
Balancing Leak-off
T between Inlet & Outlet Feed WaterTemperature.
Lubricating oil Pressure
Bearing Temperature & Vibrations.
61
Condensate Cycle
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Condensate Cycle
62
Feed water cycle
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Feed water cycle
63
PUMP CURVES
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PUMP CURVES
Pump Operating Point
System head curve Pump Head Flow curve
64
C W Pumps
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C.W.Pumps.
Flowwise , this is the largest pump in a TPS.
The Cooling Water Flow is approximately 100 timesthe steam flow condensing in the condenser.
The make up water rate is equal to the rate of steam
flow to the condenser + Drift loss + Blow down loss.
C.W. Pumps may be located close to the condenser or
Located in a separate pump house between the main
plant and the cooling towers.
These are generally vertical mixed flow pumps.
But horizontal, centrifugal pumps are also used.
65
Louvres & Drift Eliminators
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Louvres & Drift Eliminators
66
ENERGY CONSERVATION OPPORTUNITIES
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Avoiding over sizing of pump
ENERGY CONSERVATION OPPORTUNITIES
Head
Head
Partially
closed valve
Const. Speed
A
B
C
Meters
Pump Efficiency 77%
82%
Pump Curve at
Full open valve
System Curves
Operating Points
500300
50 m
70 m
Static
42 m
Flow (m3/hr)
Oversize Pump
Required Pump
67
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anilpalamwar@yahoo.com68
ENERGY CONSERVATION OPPORTUNITIES
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28.6 kW
14.8 kW
Avoiding Over sizing of Pump by
impeller trimming
ENERGY CONSERVATION OPPORTUNITIES
69
ENERGY CONSERVATION OPPORTUNITIES
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Provision of variable speed drive
ENERGY CONSERVATION OPPORTUNITIES
70
Energy Conservation Possibilities- Summary
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Energy Conservation Possibilities Summary Improvement of systems and drives.
Use of energy efficient pumps
Replacement of inefficient pumps
Trimming of impellers
Correcting inaccuracies of the Pump sizing
Use of high efficiency motors
Integration of variable speed drives into pumps: The integration of
adjustable speed drives (ASD) into compressors could lead to energy
efficiency improvements, depending on load characteristics.
High Performance Lubricants: The low temperature fluidity and high
temperature stability of high performance lubricants can increase energyefficiency by reducing frictional losses.
Booster pump application
Centralisation/ decentralisation
Categorising according to the pressure requirement71
ESP duct modification
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or ig inal arrangement . LHS half on ly is shown in the plan
ESP path#1
ESP path# 2
1.8 METER FROM APH 2-inlets
4 METER
BUS
DUCT4 OUTLETS to E.S.P.
2 x 2.5 mtr.
1.8 mtr x 6 mtr duct from APH
2.5 mtr x 4 mtr
BUS DUCT
Suggest
modification
72
MODIFICATION
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MODIFICATION
ESP path#1
ESP path# 2
2.5x2.5
2.5x2.5
ETER FROM APH 2-inlets4 OUTLETS to E.S.P.
2 x 2.5 mtr.
Recommended