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Training Session on EnergyTraining Session on Energy
EquipmentEquipment
Pumps & PumpingPumps & Pumping
SystemsSystemsPresentation from the
Energy Efficiency Guide for Industry in Asia
www.energyefficiencyasia.org
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Training Agenda: PumpsTraining Agenda: Pumps
Introduction
Type of pumps
Assessment of pumps
Energy efficiency opportunities
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IntroductionIntroduction
20% of worlds electrical energy
demand 25-50% of energy usage in some
industries
Used for Domestic, commercial, industrial and
agricultural services
Municipal water and wastewater services
What are Pumping Systems
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IntroductionIntroduction
Objective of pumping system
What are Pumping Systems
(US DOE, 2001)
Transfer liquid
from source to
destination
Circulate liquid
around a system
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IntroductionIntroduction
Main pump components
Pumps
Prime movers: electric motors, diesel engines,
air system
Piping to carry fluid
Valves to control flow in system
Other fittings, control, instrumentation
End-use equipment
Heat exchangers, tanks, hydraulic machines
What are Pumping Systems
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IntroductionIntroduction
Head
Resistance of the system
Two types: static and friction
Static head
Difference in height betweensource and destination
Independent of flow
Pumping System Characteristics
destination
source
Static
head
Static
head
Flow
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IntroductionIntroduction
Static head consists of
Static suction head (hS): lifting liquid relative topump center line
Static discharge head (hD) vertical distance
between centerline and liquid surface in
destination tank
Static head at certain pressure
Pumping System Characteristics
Head (in feet) = Pressure (psi) X 2.31
Specific gravity
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IntroductionIntroduction
Friction head
Resistance to flow in pipe and fittings
Depends on size, pipes, pipe fittings, flow
rate, nature of liquid
Proportional to square of flow rate
Closed loop systemonly has friction head
(no static head)
Pumping System Characteristics
Friction
head
Flow
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IntroductionIntroduction
In most cases:
Total head = Static head + friction head
Pumping System Characteristics
Systemhead
Flow
Statichead
Friction
head
Systemcurve
Systemhead
Flow
Statichead
Friction
head
Systemcurve
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IntroductionIntroduction
Pump performance curve
Relationship betweenhead and flow
Flow increase
System resistance increases
Head increases
Flow decreases to zero
Zero flow rate: risk ofpump burnout
Pumping System Characteristics
Head
Flow
Performancecurvefor
centrifugal pump
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IntroductionIntroduction
Pump operating point
Pumping System Characteristics
Duty point: rate
of flow at certain
head
Pump operatingpoint:
intersection of
pump curve and
system curveFlow
Head
Static
head
Pump performance
curve
System
curve
Pump
operating
point
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IntroductionIntroduction
Pump suction performance (NPSH)
Cavitation or vaporization: bubbles inside pump If vapor bubbles collapse
Erosion of vane surfaces
Increased noise and vibration
Choking of impeller passages Net Positive Suction Head
NPSH Available: how much pump suction
exceeds liquid vapor pressure
NPSH Required: pump suction needed to avoid
cavitation
Pumping System Characteristics
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Training Agenda: PumpsTraining Agenda: Pumps
Introduction
Type of pumps
Assessment of pumps
Energy efficiency opportunities
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Type of PumpsType of Pumps
Classified by operating principle
Pump Classification
DynamicPositive
Displacement
Centrifugal Specialeffect Rotary Reciprocating
Internal
gear
External
gear
LobeSlide
vane
Others(e.g.Impulse, Buoyancy)
Pumps
DynamicPositive
Displacement
Centrifugal Specialeffect Rotary Reciprocating
Internal
gear
External
gear
LobeSlide
vane
Others(e.g.Impulse, Buoyancy)
Pumps
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Type of PumpsType of Pumps
Positive Displacement Pumps
For each pump revolution
Fixed amount of liquid taken from one end
Positively discharged at other end
If pipe blocked
Pressure rises Can damage pump
Used for pumping fluids other than
water
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Type of PumpsType of Pumps
Positive Displacement Pumps
Reciprocating pump
Displacement by reciprocation of piston
plunger
Used only for viscous fluids and oil wells
Rotary pump Displacement by rotary action of gear, camor vanes
Several sub-types
Used for special services in industry
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Type of PumpsType of Pumps
Dynamic pumps
Mode of operation
Rotating impeller converts kinetic energy
into pressure or velocity to pump the fluid
Two types
Centrifugal pumps: pumping water inindustry 75% of pumps installed
Special effect pumps: specialized conditions
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Type of PumpsType of Pumps
Centrifugal Pumps
How do they work?
(Sahdev M)
Liquid forced intoimpeller
Vanes pass kinetic
energy to liquid: liquid
rotates and leaves
impeller
Volute casing converts
kinetic energy into
pressure energy
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Type of PumpsType of Pumps
Centrifugal Pumps
Rotating and stationary components
(Sahdev)
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Type of PumpsType of Pumps
Centrifugal Pumps
Impeller Sahdev)
Main rotating part that provides centrifugalacceleration to the fluid
Number of impellers = number of pump stages
Impeller classification: direction of flow, suction type
and shape/mechanical construction
Shaft
Transfers torque from motor to impeller during pump
start up and operation
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Type of PumpsType of Pumps
Centrifugal Pumps
Casings
Volute Casing(Sahdev) Functions
Enclose impeller as pressure vessel
Support and bearing for shaft and impeller
Volute case
Impellers inside casings Balances hydraulic pressure on pump shaft
Circular casing Vanes surrounds impeller
Used for multi-stage pumps
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Training Agenda: PumpsTraining Agenda: Pumps
Introduction
Type of pumps
Assessment of pumps
Energy efficiency opportunities
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Assessment of pumpsAssessment of pumps
Pump shaft power (Ps) is actual horsepower
delivered to the pump shaft
Pump output/Hydraulic/Water horsepower (Hp) isthe liquid horsepower delivered by the pump
How to Calculate Pump Performance
Hydraulic power (Hp):
Hp = Q (m3/s) x Totalhead, hd - hs(m) x (kg/m3) x g(m/s2) / 1000
Pump shaft power (Ps):
Ps = Hydraulic powerHp / pump efficiency Pump
Pump Efficiency (Pump):
Pump = Hydraulic Power/ Pump Shaft Power
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hd - dischargehead hs suctionhead,
- density ofthefluid g accelerationduetogravity
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Assessment of pumpsAssessment of pumps
Absence of pump specification data
to assess pump performance
Difficulties in flow measurement and
flows are often estimated
Improper calibration of pressuregauges & measuring instruments
Calibration not always carried out
Correction factors used
Difficulties in Pump Assessment
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Training Agenda: PumpsTraining Agenda: Pumps
Introduction
Type of pumps
Assessment of pumps
Energy efficiency opportunities
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Energy Efficiency OpportunitiesEnergy Efficiency Opportunities
1. Selecting the right pump
2. Controlling the flow rate by speed
variation3. Pumps in parallel to meet varying
demand
4. Eliminating flow control valve
5. Eliminating by-pass control
6. Start/stop control of pump
7. Impeller trimming
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Energy Efficiency OpportunitiesEnergy Efficiency Opportunities
1. Selecting the Right Pump
Pump performance curve for centrifugal
pump
BEE India,
2004
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Energy Efficiency OpportunitiesEnergy Efficiency Opportunities
1. Selecting the Right Pump
Oversized pump
Requires flow control (throttle valve or by-
pass line)
Provides additional head
System curve shifts to left
Pump efficiency is reduced
Solutions if pump already purchased VSDs or two-speed drives
Lower RPM
Smaller or trimmed impeller
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Energy Efficiency OpportunitiesEnergy Efficiency Opportunities
2. Controlling Flow: speed variation
Explaining the effect of speed
Affinity laws: relation speed N and
Flow rate Q E N
Head H E N2
Power P E N3
Small speed reduction (e.g. ) = large
power reduction (e.g. 1/8)
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Energy Efficiency OpportunitiesEnergy Efficiency Opportunities
Variable Speed Drives (VSD)
Speed adjustment over continuousrange
Power consumption also reduced!
Two types Mechanical: hydraulic clutches, fluid couplings,
adjustable belts and pulleys
Electrical: eddy current clutches, wound-rotor
motor controllers, Variable Frequency Drives
(VFDs)
2. Controlling Flow: speed variation
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Energy Efficiency OpportunitiesEnergy Efficiency Opportunities
Benefits of VSDs
Energy savings (not just reduced flow!)
Improved process control
Improved system reliability
Reduced capital and maintenance
costs
Soft starter capability
2. Controlling Flow: speed variation
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3. Parallel Pumps for Varying Demand
Multiple pumps: some turned off during low
demand
Used when static head is >50% of total head
System curve
does not change
Flow rate lowerthan sum of
individual
flow rates
(BPMA)
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Energy Efficiency OpportunitiesEnergy Efficiency Opportunities
4. Eliminating Flow Control Valve
Closing/opening discharge valve (throttling)
to reduce flow
Head increases:
does not reduce
power use
Vibration andcorrosion: high
maintenance
costs and reduced
pump lifetime
(BPMA)
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Energy Efficiency OpportunitiesEnergy Efficiency Opportunities
5. Eliminating By-pass Control
Pump discharge divided into two
flows One pipeline delivers fluid to destination
Second pipeline returns fluid to the source
Energy wastage because part of fluidpumped around for no reason
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Energy Efficiency OpportunitiesEnergy Efficiency Opportunities
6. Start / Stop Control of Pump
Stop the pump when not needed
Example:
Filling of storage tank
Controllers in tank to start/stop
Suitable if not done too frequently
Method to lower the maximum
demand (pumping at non-peak hours)
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Energy Efficiency OpportunitiesEnergy Efficiency Opportunities
7. Impeller Trimming
Changing diameter: change in
velocity
Considerations
Cannot be used with varying flows
No trimming >25% of impeller size
Impeller trimming same on all sides
Changing impeller is better option but more
expensive and not always possible
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Energy Efficiency OpportunitiesEnergy Efficiency Opportunities
7. Impeller Trimming
Impeller trimming and centrifugal pump performance
(BEE India,
2004)
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Energy Efficiency OpportunitiesEnergy Efficiency Opportunities
Comparing Energy Efficiency
Options
Parameter Change
control valve
Trim impeller VFD
Impeller
diameter
430 mm 375mm 430 mm
Pump head 71.7m 42 m 34.5m
Pump efficiency 75.1% 72.1% 77%
Rate of flow 80 m3/hr 80 m3/hr 80 m3/hr
Power
consumed
23.1 kW 14 kW 11.6 kW
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Training Session on EnergyTraining Session on Energy
EquipmentEquipment
Pumps & PumpingPumps & Pumping
SystemsSystems
THANK YOUTHANK YOU
FOR YOUR ATTENTIONFOR YOUR ATTENTION
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Disclaimer and ReferencesDisclaimer and References
This PowerPoint training session was prepared as part of
the project Greenhouse Gas Emission Reduction from
Industry in Asia and the Pacific (GERIAP). While
reasonable efforts have been made to ensure that the
contents of this publication are factually correct andproperly referenced, UNEP does not accept responsibility for
the accuracy or completeness of the contents, and shall not
be liable for any loss or damage that may be occasioned
directly or indirectly through the use of, or reliance on, the
contents of this publication. UNEP, 2006.
The GERIAP project was funded by the Swedish
International Development Cooperation Agency (Sida)
Full references are included in the textbook chapter that is
available on www.energyefficiencyasia.org