Pump Efficiency and System Optimization

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

3

“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.

4

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

5

Why Efficient Pumping Systems are Important

6

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.

11

System Components and Interaction

14

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!

15

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!

16

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%

28

Pump Basics

29

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

30

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

31

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.

32

Understanding a Pump Performance Curve

33

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.

34

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.

35

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)

36

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.


Hea

d (P

ress

ure)

Capacity (Flow GPM)

37

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).


Hea

d (P

ress

ure)

Capacity (Flow GPM)

Pow

erK

W

Operating Point

Power Required

38

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.


Hea

d (P

ress

ure)

Capacity (Flow GPM)

B.E.P.

Peak Efficiency

Effic

ienc

y %

39

Efficiency


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 %

40

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).


Hea

d (P

ress

ure)

Capacity (Flow GPM)

Peak EfficiencyOperating Efficiency

Effic

ienc

y %

Operating PointB.E.P.

41


Hea

d (P

ress

ure)

Capacity (Flow GPM)

Pow

erK

WEf

ficie

ncy

%

Efficiency

Flow

Head

Power

Operating PointPump CurveSystem Curve

Review

42

Off‐BEP Operation

Vibration Axial Loads Radial Loads Suction Recirculation

Excessive Discharge Pressure

Low Flow Operation Increases:

BEP

LowFlow

43

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

44

Operating at or near BEP means Reliability ‐Weibull

Source: © Paul Barringer & Associates, Inc, http://www.barringer1.com/oct97prb_files/Pump%20Practices%20&%20Life.pdf

45

Simplified – 5 Important Points

Shutoff headBEP

AOR

MCSF50% of Design

Run-out120% of design

53

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

57

Net

P ositiveSuctionHead

58

NPSHa > NPSHr(available) (required)

No Exceptions!

60

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.

61

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.

62

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.

63

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.

64

Pressure Through a Pump Illustrated

65

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.

66

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.

67

Motors and Pumps

68

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

69

Think System

70

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

71

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

72

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

73

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

77

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.

78

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

80

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

82

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”

83

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)

87

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

88

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

89


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


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


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

98

Pump Affinity Laws

99

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)

102

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

104

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

118

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.

129

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

133

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

154

Taking Advantage of Variable Speed Pumping

Affinity Laws

%SPEED

% F

LOW

, HEA

D, P

OW

ER

156

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

157

Modifying Pump Curves for Speed Changes

Same as changes in impeller trim < 10-15%

169

Developing The Action Plan

170

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

171

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

173

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

174

Efficiency Incentive Programs

http://www.dsireusa.org/

DSIREData Base for State Incentives for Renewable Energy and Efficiency

175

Efficiency Incentive Programs

176

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

177

Contact

Benjamin StevensManager of Engineering Services

AW Chesterton [email protected]

O – 978-469-6317C – 617-699-5591

178

Questions, Comments and Discussion

Documents

Pump Efficiency and System Optimization