pump efficiency and system optimization
TRANSCRIPT
Pump Efficiency and OptimizationA system approach to reducing energy and
improving reliability
2
Presenter
Benjamin StevensManager of Engineering Services
AW Chesterton Company – Fluid Efficiency Division
10+ Years @ AW Chesterton04’ Grad of Mass Maritime Academy – Marine Engineering
Active with:Hydraulic Institute – Pump Systems Matter
Society of Maintenance and Reliability Professionals
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“Pumping systems.…..”
a) are critical to plant operation.b) consume a significant amount of
electricity.c) are expensive to maintain and repair.d) are often misunderstood, costing the
end user significantly.
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Agenda
1. Why Efficient Pumping Systems Are Important
2. System Components and Interaction
3. Screening Pump Systems
4. Analysis Tools
5. Improving Performance of Existing Systems
6. Developing The Action Plan
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Why Efficient Pumping Systems are Important
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Electrical Energy Savings Potential – Industrial Plants
Source: U.S. Industrial Motor Systems, Market Opportunities Assessment,U.S. Department of Energy
GWhr / Year
Pumps Systems are Energy Intensive
7
Energy Use by SystemPumping systems account for 15-20% of electricity use in
wastewater and up to 90% in fresh water systems .
8
Finnish Technical Research Center Report: "Expert Systems for Diagnosis of the Condition and Performance
of Centrifugal Pumps"
Evaluation of 1690 pumps at 20 process plants:• Average pumping efficiency is below 40%• Over 10% of pumps run below 10% efficiency• Major factors affecting pump efficiency:
– Throttled valves– Pump over-sizing– Worn internals
• Poor operation resulting in seal leakage • Highest cause of downtime • Highest cost
Impact on Life Cycle Cost?
9
Pump Efficiency Loss Over Time
In a paper published by the Hydraulic Institute, Pump Life Cycle Costs, it is estimated that 20% of the worlds energy demands are
consumed by pumping systems.
Source: European Union Save Report - 2001
10
Technical Standards
Pumps SystemsANSI With a few exceptions there
are no system standards.
Engineering firms, contractors and owner/operators are allowed to design and build systems while ignoring system hydraulic characteristics.
Hydraulic Institute
API
DIN
ISO
NFPA
ASME
There is a plethora of standards for the components that make up a system but nothing governs the system as a whole.
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System Components and Interaction
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Electrical Energy Cost – Centrifugal Loads
100 HP Induction Motor100% Speed100% Load
(100HP) / (95% Efficiency) X (.746 kW/HP) X (.08 $/kWh) X (12Hr/D) X (365 D/Yr)
$27,515 per year!
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Electrical Energy Cost – Centrifugal Loads
100 HP Induction Motor60% Speed22% Load
(22HP) / (95% Efficiency) X (.746 kW/HP) X (.08 $/kWh) X (12Hr/D) X (365 D/Yr)
$6,053 per year!
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Affinity Laws for Centrifugal Loads
Speed Volume Pressure/Head
HP Required
100% 100% 100% 100%90% 90% 81% 73%80% 80% 64% 51%70% 70% 49% 34%60% 60% 36% 22%50% 50% 22% 13%
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Pump Basics
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Pump Basics• Two basic types:
– Rotodynamic (most commonly centrifugal)– Positive Displacement (PD) Pumps:
• Centrifugal Pumps use an impeller and volute to create the partial vacuum and discharge pressure necessary to move water through the casing. The impeller and volute form the heart of the pump and help determine its flow, pressure and solid handling capability.
• PD Pumps move liquids by pressurizing them
This training session will focus exclusively on Centrifugal Pumps
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Centrifugal Pump Operation
HEADTherefore, the head (pressure in terms of height of liquid) developed is approximately equal to the velocity energy at the periphery of the impeller.
A centrifugal pump converts Kinetic Energy (Velocity) to Pressure Energy
1. The amount of energy given to the liquid is proportional to the velocity at the edge or vane tip of the impeller
2. The faster the impeller revolves or the bigger the impeller is, then the higher will be the velocity of the liquid at the vane tip and the greater the energy imparted to the liquid.
3. This kinetic energy of a liquid coming out of an impeller is harnessed by creating a resistance to the flow.
The first resistance is created by the pump volute (casing) that catches the liquid and slows it down.
4. In the discharge nozzle, the liquid further decelerates and its velocity is converted to pressure according to Bernoulli’s principle.
Impeller Eye
Impeller Volute
Discharge
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Centrifugal Pump Facts
• Centrifugal pumps should be selected and normally operated at or near the manufacturer’s design rated conditions of head and flow.
• Any pump operated at excess capacity, i.e. at a flow significantly greater than BEP and at a lower head, will surge and vibrate, creating potential bearing and shaft seal problems as well as requiring excessive power.
• When operation is at reduced capacity, i.e. at a flow significantly less than BEP and at a higher head, the fixed vane angles will now cause eddy flows within the impeller, casing, and between the wear rings. The radial thrust on the rotor will increase, causing higher shaft stresses, increased shaft deflection, and potential bearing and mechanical seal problems while radial vibration and shaft axial movement will also increase.
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Understanding a Pump Performance Curve
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What is on a Pump Performance Curve?A pump curve or performance curve shows the total head, power, efficiency and NPSHr
curves plotted against rate of flow
Head is the “pressure” developed across the pump Power is typically expressed in break horsepower – the power required of the
driver output shaft Efficiency is the relationship between hydraulic work (water horsepower) and
input rotational work NPSHr is the required liquid pressure at the suction end of a pump. Insufficient
NPSH can allow cavitation in a pump or reduced performance NPSHa is the actual pressure at inlet of the pump (NPSHa should be greater than
NPSHr)
There is a LOT of data contained on one sheet of paper! The pump curve is absolutely essential to assessing the
efficiency of our system.
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Pump Curve
Understanding Pump Performance
Hea
d (P
ress
ure)
Capacity (Flow GPM)
Pumps are sized based on the pressure and flow rate required of the system.
The head is measured by the Y, or vertical, axis and the capacity is measured by the X, or horizontal, axis. For the purpose of this discussion head can be described as the liquid pressure and the capacity is the liquid flow rate.
The head and flow move inversely with each other.
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System CurveEvery pumping system has a curve plotting the relationship between head and capacity.
One can see that as the flow demand through a system becomes greater a corresponding increase in pressure is required (opposite of a pump curve).
Where does the pump operate on it’s curve?
Hea
d (P
ress
ure)
Capacity (Flow GPM)
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Operating PointIn a fixed speed system, the system curve and pump curve, overlaid on the same graph, intersect at one point.
This intersection is known as the operating point. The head and capacity at this point is a known value from which pump efficiency and power requirements can be determined.
Understanding Pump Performance
Hea
d (P
ress
ure)
Capacity (Flow GPM)
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Power RequirementThe power required to develop the specified flow is also plotted on the graph, represented here by the red curve.
Drawing a vertical line downward from the operating point will determine the power consumed by the pump, as read by the secondary scale on the Y axis (right hand side of graph).
Understanding Pump Performance
Hea
d (P
ress
ure)
Capacity (Flow GPM)
Pow
erK
W
Operating Point
Power Required
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EfficiencyWhen we talk about pump efficiency we are referring to how much mechanical work is converted into hydraulic work. In other words, what percent of the motor output results in liquid flow and pressure?
As a result of inherent losses in all pumps, 100% efficiency is not attainable. A number between 80% and 90% would be more common. Represented by the green curve on the graph, the efficiency varies as a result of the flow requirements.
Understanding Pump Performance
Hea
d (P
ress
ure)
Capacity (Flow GPM)
B.E.P.
Peak Efficiency
Effic
ienc
y %
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Efficiency
Understanding Pump Performance
Hea
d (P
ress
ure)
Capacity (Flow GPM)
B.E.P.
Peak Efficiency
The most efficient operating point of a given pump is determined by drawing a vertical line through the peak of the efficiency curve.
Where this line intersects the pump curve is referred to as best efficiency point, or B.E.P.
The pump is not only the most efficient at B.E.P., it will also run the most reliably. Operation on the pump curve to the right or left can result in cavitation, vibration, overheating and contact with non-moving parts.
Effic
ienc
y %
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EfficiencyA pump will rarely operate at it’s B.E.P. However when sizing a pump for a specific application every effort is made to match the best efficiency point as close as possible to the required operating point.
To determine the efficiency of a pump in a given system we must draw a vertical line from the operating point downward. Where this line intersects the efficiency curve is the operating efficiency of the pump, as read from the scale on the secondary Y axis (right hand side of graph).
Understanding Pump Performance
Hea
d (P
ress
ure)
Capacity (Flow GPM)
Peak EfficiencyOperating Efficiency
Effic
ienc
y %
Operating PointB.E.P.
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Understanding Pump Performance
Hea
d (P
ress
ure)
Capacity (Flow GPM)
Pow
erK
WEf
ficie
ncy
%
Efficiency
Flow
Head
Power
Operating PointPump CurveSystem Curve
Review
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Off‐BEP Operation
Vibration Axial Loads Radial Loads Suction Recirculation
Excessive Discharge Pressure
Low Flow Operation Increases:
BEP
LowFlow
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Run‐out Flow issues vs. BEP
BEP
HighFlow
Run‐out Flow Operation:• Increased Vibration • Increased Radial Load• High/Steep NPSHR Curve• Decreased Discharge
Pressure• Reduced Seal and Bearing
Life• Increased Cavitation and
Potential Damage to Impeller and Case
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Operating at or near BEP means Reliability ‐Weibull
Source: © Paul Barringer & Associates, Inc, http://www.barringer1.com/oct97prb_files/Pump%20Practices%20&%20Life.pdf
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Simplified – 5 Important Points
Shutoff headBEP
AOR
MCSF50% of Design
Run-out120% of design
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Specific Speed and Efficiency
Where are the losses?
100%
95%
90%
75%
85%
80%
70%1 2 3 4 5 6 7
Pum
p Ef
ficie
ncy
Specific Speed (Ns) x 1000
This well known graph illustrates the magnitude of friction and leakage losses on the left end of the pump specific speed spectrum.2These losses will increase over time as a result of wear and degradation.
1) Mechanical Losses – 1%2) Impeller Losses – 2.5%3) Disc Friction Losses4) Leakage Losses5A)Casing Losses – Vertical5B)Suction Losses – Double Suction6) Pump Output
3 5a
6
4
1 2
5b
2. Centrifugal and Axial Flow Pumps by A.J. Stepanoff, published by John Wiley and Sons 1957
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Net
P ositiveSuctionHead
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NPSHa > NPSHr(available) (required)
No Exceptions!
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NPSH Defined
NPSH (Net Positive Suction Head) is the total suction head in feet of the liquid being pumped (at the centerline of the impeller eye) less the absolute vapor
pressure of the liquid.
NPSHa = ha – hvpa± hst – hfs
Where:
ha = absolute pressure (in feet of liquid being pumped) on the surface of the liquid supply level (if open tank, barometric pressure); or the absolute pressure existing in a closed tank
hvpa = the head in feet corresponding to the vapor pressure of the liquid at the temperature being pumped
hst = static height in feet that the liquid supply level is above or below the pump centerline or impeller eye
hfs = all suction losses (in feet) including entrance losses and friction losses through pipe, valves, and fittings, etc.
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NPSHa = Net Positive Suction Head Available
static height in feet that the liquid supply level is above or below the pump centerline or impeller eye
the head in feet corresponding to the vapor pressure of the liquid at the temperature being
pumped
absolute pressure (in feet of liquid being pumped) on the surface of the liquid supply level (if open tank, barometric pressure); or the absolute pressure existing in a closed tank
all suction losses (in feet) including entrance losses and friction losses through pipe, valves, and fittings, etc.
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Vapor Pressure of Water
Temperature (ºF) Vapor Pressure (PSIG)
212º 0
230º 6
240º 11
At a given temperature, if the water pressure drops below its vapor pressure, some of the water will flash
into steam. This is gauge pressure.
Because of the low pressures at the impeller eye this is important to understand.
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Vapor Pressure and Cavitation
If the pressure of water drops below its vapor pressure, vapor pockets will form.
When the pressure of the water is later increased above its vapor pressure, the vapor pockets will collapse. The pressure of this implosion can be 100,000 PSI!!!
The collapse of these vapor pockets is known as cavitation.
Cavitation will cause damage.
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Pressure Through a Pump Illustrated
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Effects of Cavitation on Pump
• Pump cavitation is noisy! (Audible Cavitation Vs Insipient)• Pump impeller damage due to vapor bubble formation and
collapse• Pump curve will change drastically. The pump cannot deliver
both liquid and vapor.• Pump shaft can be broken because of slugging of the impeller
against alternate bodies of liquid, vapor, and air.• Pump seal failure because the vapor flash causes “dry” seal
operation and rapid wear.
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What do the Effects of Cavitation Look Like?
Damage on the tail end of the impeller blades would typically be
an indication of vaporization cavitation. Insufficient NPSHa.
Damage on the leading edge of the impeller blades would typically be an indication of
recirculation cavitation.
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Motors and Pumps
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Motor and Pump – “The Odd Couple”
Electric motors maintain high efficiencyOver a wide range
35% load to 120% load Centrifugal pumps have a very narrow operating range
-20% to +10%
The motor and pump react to system requirements and therefore operate based on system resistance.The pump reliability and performance is highly influenced by the system
Acceptable Operating Range
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Think System
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What is System Optimization?
“The process of identifying, understanding, and cost effectively eliminating unnecessary losses while reducing energy consumption and improving reliability in pumping systems, which while meeting process requirements, minimizes the cost of ownership over the economic life of the pumping systems.”
Source: Optimizing Pumping Systems: A Guide to Improved Energy, Efficiency, Reliability and Profitability
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Using a Systems Approach to Manage Pumping System
Focusing solely on individual components overlooks potential cost‐savings
Component failures are often caused by system problems (How do you identify these problems?)
Use a life cycle cost approach in designing systems and evaluating repair and maintenance options
Remember the energy bill discussion vs. first cost
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Pumps and Systems
A pump must overcome two fundamental system‐related aspects: Friction Static Liquid elevation differences between supply and discharge Pressure differences between supply and discharge
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What is a System Curve?
A system curve represents the sum of the static head and the friction loss due to flow of fluid through a system. The pumping system will operate where the pump and system curves intersect
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Static Head in Pumping Systems
Influent Pump
Wet Well
Discharge Basin
The elevation difference between the liquid level of the pump suction source and the liquid level of the discharge location.
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Friction in Pumping Systems
Friction occurs in pump systems due to irrecoverablehydraulic losses in: Piping Valving Fittings (e.g., elbows, tees) Equipment (e.g., heat exchangers)
Friction is also used to control flow or pressure, recoverable hydraulic losses Automated flow and pressure control valves Orifice Plates Manual throttling valves
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Calculating System Resistance Theoretically
Darcy Weisbach Formula
hf = f (L/D) x (v2/2g)
Where;hf = head loss (ft)f = friction factor*L = length of pipe work (ft)d = inner diameter of pipe work (ft)v = velocity of fluid (ft/s)g = acceleration due to gravity (ft/s²)
*Derived from the Moody diagram
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Calculating System Resistance
The Darcy Weisbach Equation can be interpreted to say the head resistance in a system varies as
the square of the flow.
∆hf } (∆Q)2
The more fluid you pump, and the faster you pump it, will increase the friction losses.
“System Affinity”
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System Curve – Friction Head + Static Head
htotal = k(Q2)+ hstatic
where;htotal = total dynamic head (feet)k = friction coefficient describing characteristics of total systemQ = flowhstatic = system static head (feet)
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System Curve ‐ Components
Operating Point
Tota
l Dyn
amic
Hea
d
Flow
Static Head
Dynamic Head
Dynamic:Pipe length, diameter, internal roughness, fittings, etc..
Static:Pump elevation, tank level, wet well level, pressure differential, etc…
Hf
Hs
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System Curve – Alterations – Example 1
Operating PointH
ead
(Pre
ssur
e)
Capacity (Flow GPM)
Dynamic:What effect does closing a valve have on system operation?
“Steepens” the dynamic component,
resulting in Increased Head
(resistance),Less Flow
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System Curve – Alterations – Example 2
Operating PointH
ead
(Pre
ssur
e)
Capacity (Flow GPM)
Dynamic:What effect does less friction have on the system curve? Recirculation?Fire Hydrant.
“Flattens” the dynamic component resulting in
Decreased Head (resistance),
More Flow
90
System Curve – Alterations – Example 3
Operating PointH
ead
(Pre
ssur
e)
Capacity (Flow GPM)
Static:What effect does a decreased storage tank level have on the system curve?
Increases static head (Y intercept of curve)
resulting in Less Flow
91
System Curve – Alterations – Example 4
Operating PointH
ead
(Pre
ssur
e)
Capacity (Flow GPM)
Dynamic:What effect does an increased storage tank level have on a system curve?
Decreases static head (Y intercept of curve)
resulting in More Flow
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Pump Affinity Laws
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The Affinity Laws – Centrifugal Pumps
1.Flow (capacity) varies proportionally to changes in impeller speed or diameter.
2.Pressure (or head) varies as the square of changes to the impeller speed or diameter.
3.Power required (BHP or kW) varies as the cube of changes to the impeller speed or diameter.
100
The Affinity Laws – EquationsThe Affinity Laws are mathematical expressions that define changes in pump capacity, head, and BHP when a change is made to pump speed, impeller diameter, or both. According to Affinity Laws:
• Capacity, Q changes in direct proportion to impeller diameter D ratio, or to speed N ratio:
Q2 = Q1 x [D2/D1]Q2 = Q1 x [N2/N1]
• Head, H changes in direct proportion to the square of impeller diameter D ratio, or the square of speed N ratio:
H2 = H1 x [D2/D1]2
H2 = H1 x [N2/N1]2
• BHP changes in direct proportion to the cube of impeller diameter ratio, or the cube of speed ratio:BHP2 = BHP1 x [D2/D1]3
BHP2 = BHP1 x [N2/N1]3
Where the subscript: 1 refers to initial condition, 2 refer to new conditionIf changes are made to both impeller diameter and pump speed the equations can be combined to:
Q2 = Q1 x [(D2xN2)/(D1xN1)]H2 = H1 x [(D2xN2)/(D1xN1)]2
BHP2 = BHP1 x [(D2xN2)/(D1xN1)]3
This equation is used to hand-calculate the impeller trim diameter from a given pump performance curve at a bigger diameter.
The Affinity Laws are valid only under conditions of constant Load.
101
The Affinity Laws – Centrifugal Pumps
In other words….Slowing a pump by 50% will;
Reduce the flow to 50% (1/2)
Reduce the head to 25% (1/4)
Reduce the power required to 12.5% (1/8)
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Impeller Size Changes
Using the affinity rules the pump head curve can be adjusted for a different diameter impeller
Efficiency Curves
103
Pump Speed Changes
Using the affinity rules the pump head curve can be adjusted for different SPEEDS.
Efficiency Curves
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Pump Speed Changes
Friction-Dominated Systems
105
Pump Speed Changes
Static-Dominated Systems
106
ConclusionA change in impeller speed or a change in impeller diameter has approximately the same effect. This is true only if you decrease the impeller diameter to a maximum of 10% . As you cut down the impeller diameter, the housing is not coming down in size so the affinity laws do not remain accurate below this 10% maximum number.
The affinity laws remain accurate for speed changes and this is important to remember when we promote variable frequency drives.
114
Screening Pumping Systems
116
Why Screen?
Most industrial and municipal plants have tens, hundreds, or even thousands of pumping systems
Screening the pumping systems identifies specific systems for further analysis
These pumps will be the best candidates for further study to identify energy savings opportunities
117
Pump System Screening
Use Pump System Basic Assessment Guide Pre‐screening Form or similar tool
On‐site inspection & Gathering data – Walk Through Data analysis that prioritize opportunities Selection of pumps for further analysis
Post‐Screening ‐ Work with appropriate pumping system specialist and/or in‐
house team to gather and analyze additional system data Develop, economically justify, and implement performance
improvement opportunities
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Pre‐screening Form
123
Prioritize the Opportunities
Rank pumps with opportunities for performance improvement
Focus on energy use, those with maintenance problems, etc.
124
End Result from Pre‐Screening
List of pump systems and solutions that can be implemented immediately without further analysis
List of pump systems that need further analysis System’s conditions that are steady and a snapshot of performance data is required for the analysis
OR There are changes in system demand over time and the system must be monitored over a longer period of time
125
Select Pumping Systems for Further Analysis
Review ability of plant staff to collect additional data and provide solutions
Consider using an outside pump system specialist Contact your electric utility
126
System Assessment Standard – EA‐2‐2009
Section 1‐3: Scope, Definitions and References
Section 4: Organizing the Assessment Section 5: Conducting the Assessment Section 6: Analysis of Data Section 7: Reporting and Documentation Next Steps
128
ASME EA‐2‐2009
Three Levels of Assessments
Level 1 Qualitative (prescreening) investigation to identify energy
optimization potential.Level 2
Quantitative (measurement based) investigation to determine the energy saving potential for at least one operating condition
within a limited time frame.Level 3
Quantitative investigation over an extended period of time sufficient to develop a system load profile.
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Standards for Performing System AssessmentsISO/ASME 14414:2015 - Pump System Energy Assessment
ForewordIntroduction1 Scope2 Normative references3 Terms and definitions4 Identification of the assessment team, authority and functions5 Conducting the Assessment6 Reporting and documentationAnnex A Report ContentsAnnex B Recommendations on efficient system operation and energy reduction - ExamplesAnnex C Expertise, experience and competenciesAnnex D Recommended guidelines for analysis softwareAnnex E Example of prescreening worksheetAnnex F Specific EnergyAnnex G Pumping system parasitic powerAnnex H Example of pumping system efficiency indicatorBibliography
130
Key Points
Screening is the first step to improving the performance of your pumping systems
Screening allows you to prioritize your opportunities Screening provides valuable information on how many systems should be further assessed
131
Analysis Tools
132
Various Tools Available
Pump system specialists use a variety of tools to analyze pumping systems
Examples: US DOE’s PSAT – Gather field measurements and focus on identifying
energy savings opportunities PSM’s P‐SMART – Educational tool to model current system and
proposed changes to improve performance More tools available in PSM Tool Matrix (both free and commercially
available) Many pump system specialists have their own proprietary tool or use
excel spreadsheets Most pump system specialists feel that multiple tools are needed
during an assessment
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Data Input Screen – DOE PSATInput data
Results
Measuredfield data
Nameplatetype data
Duty, costdata
134
Valve Analysis – DOE PSAT
135
Pump Head – DOE PSAT
Accounts for suction losses, gauge elevation, velocity head, etc….
136
System Curve – DOE PSAT
Simple System – more complex systems require greater analysis
137
System Modeling ‐ P‐SMART, Hydraulic Institute
Commercially available from Engineered Software Inc.
Uses Cv to calculate pressure drop with Haizen Williams formula
138
System Modeling ‐ P‐SMART, Hydraulic Institute
Sizes pump according to system requirements (capacity vs. head loss)
139
MS Excel – “Old Reliable”
Nameplate Test Point 1 Modified OEM Curve 856.7 RPM System Curve Measured RPM
Speed Control Fixed Wire Water 856.7 TDH Flow BHP Eff TDH FlowMotor BHP 700 Test Location Line Flow (GPM) 9500 Feet GPM Feet GPMMotor RPM 514 Volts 4160 Discharge PSI 35 Shut‐off 330.6 0.0 0.0 #DIV/0! Static Head 60.0 0.0Motor Eff 93% Amps 66.5 Suction PSI 1 1 325.0 8333.7 1296.4 52.8% 1 74.3 8333.7Motor PF 0.9 PF 0.96 2 311.1 16667.3 1666.9 78.6% 2 117.1 16667.3VFD Eff (100% if not) 98% Speed Unit Hz Total Dynamic Head (feet) 78.5 3 288.9 25001.0 2037.3 89.5% 3 188.4 25001.0VFD PF (1.0 if not) 0.98 Speed 100 Water HP 188.4 4 255.6 33334.6 2361.4 91.1% 4 288.3 33334.6Volts 4160 Hydraulic Eff 32.9% 5 208.3 41668.3 2592.9 84.6% 5 416.7 41668.3Amps 100 6 138.9 50001.9 2685.5 65.3% 6 573.6 50001.9Flow 22,000 kVA 479.155 System 7 0.0 0.0 0.0 0.0% 7 60.0 0.0Head 100 kW 459.988 System Static Head (feet) 60.0 8 0.0 0.0 0.0 0.0% 8 60.0 0.0Sp Gravity 1.0 Brake HP 573.444 9 0.0 0.0 0.0 0.0% 9 60.0 0.0
Friction Coeficient 2.054E‐07 10 0.0 0.0 0.0 0.0% 10 60.0 0.0Red = Inputs 11 0.0 0.0 0.0 0.0% 11 60.0 0.0Green = Calculated 12 0.0 0.0 0.0 0.0% 12 60.0 0.0
Test Point 2 Modified OEM Curve System Curve Measured RPMWire Water 450.0 TDH Flow BHP Eff TDH FlowTest Location Line Flow (GPM) 8000 Feet GPM Feet GPMVolts 4160 Discharge PSI 30 Shut‐off 91.2 0.0 0.0 #DIV/0! Static Head 58.0 0.0Amps 54 Suction PSI 1 1 89.7 4377.4 187.9 52.8% 1 60.7 4377.4PF 0.96 2 85.8 8754.9 241.6 78.6% 2 68.8 8754.9Speed Unit RPM Total Dynamic Head (feet) 67.0 3 79.7 13132.3 295.3 89.5% 3 82.2 13132.3Speed 450 Water HP 135.3 4 70.5 17509.7 342.2 91.1% 4 101.1 17509.7
Hydraulic Eff 29.1% 5 57.5 21887.2 375.8 84.6% 5 125.3 21887.26 38.3 26264.6 389.2 65.3% 6 154.9 26264.6
kVA 389.088 System 7 0.0 0.0 0.0 0.0% 7 58.0 0.0kW 373.524 System Static Head (feet) 58.0 8 0.0 0.0 0.0 0.0% 8 58.0 0.0Brake HP 465.654 9 0.0 0.0 0.0 0.0% 9 58.0 0.0
Friction Coeficient 1.405E‐07 10 0.0 0.0 0.0 0.0% 10 58.0 0.011 0.0 0.0 0.0 0.0% 11 58.0 0.012 0.0 0.0 0.0 0.0% 12 58.0 0.0
140
MS Excel – “Old Reliable”
142
Key Points
There are many no cost tools available from various organizations
However, there is no “one size fits all” tool for pump assessments
We must understand the components of a pumping system and how they interact with each other before using the analysis tools
Consider all potential solutions to improve performance of systems
Validate, from an economic standpoint, and choose the most cost effective solutions
143
Improving Performance of Existing Systems
145
Define the System Boundaries
MCCF1P
P
Input
F2Beware of “Scope-creep”
146
Performance Improvement Solutions
Eliminate unnecessary uses
Improve Operations & Maintenance (O & M) practices
Improve piping configuration
Consider alternative pump configurations
Change pump speed
Trim Impeller
Reduce Internal Frictions
147
Unnecessary Use of Energy
Using a pump when the fluid is not needed
Running two pumps when only one is needed
Continuing to run pumps in a batch‐type process whenproducts are not being produced (recirculation)
Excessive pump head or flow – sized incorrectly?
148
System Opportunities
Systems controlled by throttle valves
High operating hours per year
Recirculation or bypass line normally open
Cavitation noise at valves, pumps, or piping
Systems with multiple parallel pumps always operating
Constant pump operation in a batch environment or frequent cycle batch operation in a continuous process
149
System Opportunities (continued)
• Systems that have undergone a change
• Variability of operation
• High system maintenance
• Motor tripping out
• Larger pumps
• Excessive seal leakage & packing problems
150
Excessive Valve Throttling is Expensive
Lower pump and process reliability
Higher energy consumption
Sub‐optimal process control
increased variability
manual operation
Pumps are tightly associated with control loops and should be considered an integral part of the automation architecture
152
Eliminating Control Valves by Changing Pump Speed
Slower motor (fixed speed) Two‐speed motor * Changes to belt drives/gears * Variable Speed Drives Variable Frequency Drive Magnetic Drive Fluid Drive
153
Variable Speed Pumping
Why use a variable speed pump? Slowing down/speeding up mis‐sized pumps
When to use variable speed? Pressure Control Variable Flow
When not to use variable speed? Static Dominated Systems Frequent Start/Stop
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Taking Advantage of Variable Speed Pumping
Affinity Laws
%SPEED
% F
LOW
, HEA
D, P
OW
ER
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Decision Tree for VFD’s
Consider System Dem ands
Start
Confirm system and duration curves. Establish if not
available.
Consider reducing system losses
Is duty available?
VFD potentially useful
Confirm existing fixed speed pum p correctly
sized
Consider m odification or replacem ent
equipmentNO NO
Retain existing installation if efficient
Mostly friction (rotodynam ic only)
VFD potentially usefulIs VFD suitable?
Are existing pum p and m otor suitable for
proposed variable speed
Does pum p run m ost of the tim e?
VFD alm ost certainly beneficial
Calculate total annual operating cost w ith alternative system
solutions
NO
NO
YES
Check overall benefits include non energy item s ie: reduced m aintenance cost
Select drive and perform financial justification
YES
NO
NO
YES
YES
YES
Flow Chart to assess the suitability of retrofitting a VSD to an existing pump system
urce – Hydraulic Institute LCC Guide Book
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Modifying Pump Curves for Speed Changes
Same as changes in impeller trim < 10-15%
169
Developing The Action Plan
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Six Step Action Plan
1. Gain management support for improving high priority and critical pumping systems
2. Screen and prioritize your pumping systems to identify good performance improvement opportunities
3. Assemble a team with appropriate pump system specialists, operations, maintenance and engineering
4. Identify, economically validate, and implement performance improvement plan
5. Document the actions taken and report results to management
6. Repeat the action plan process for other good candidate systems
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Key Points
If you want to improve your pumping systems, follow the plan: Create a partnership between production, management, purchasing, etc.
Find out what they consider important Begin with something small and involve production Always document everything that you do Partner with appropriate pump system experts Measure and report the impact of system changes in terms that are important to management and production (show them the money)
Use life cycle cost analysis
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Where to go to get Help
• Visit the these Website Resources: •www1.eere.energy.gov/industry•www.superiorenergyperformance.net•www.PumpSystemsMatter.org•www.Pumps.org•www.chesterton.com•www.weg.com•www.energyquickstart.org
• Send your staff to webinars and courses available from the DOE, PSM, Hydraulic Institute and others
• Explore local efficiency programs and utility rebates!• Bring in a pumping system specialist to help you• Purchase the ASME Energy Assessment for Pumping Systems
Standard
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Efficiency Incentive Programs
http://www.dsireusa.org/
DSIREData Base for State Incentives for Renewable Energy and Efficiency
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Efficiency Incentive Programs
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AcknowledgementsIn addition to those mentioned throughout this presentation, we would like to acknowledge the following organizations for their contributions to the content for this course: Engineering Software, Inc. • WEG Electric Corp• Manitoba Hydro• Grundfos, USA• Department of Energy/Industrial Technologies Program• Flowserve Corporation• Hydro, Inc. • ITT Industrial Process• Applied Flow Technology• AW Chesterton Company
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Contact
Benjamin StevensManager of Engineering Services
AW Chesterton [email protected]
O – 978-469-6317C – 617-699-5591
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Questions, Comments and Discussion