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Presentation to:Presentation to:Presentation to:Presentation to:2010 Michigan MWEA Process Seminar 2010 Michigan MWEA Process Seminar O ti Effi iO ti Effi i D i M ith LD i M ith LOperation Efficiency Operation Efficiency –– Doing More with LessDoing More with Less

On:

Effective Turndown of Aeration Air Blowers for

On:

Effective Turndown of Aeration Air Blowers forEffective Turndown of Aeration Air Blowers for Electricity Cost SavingsEffective Turndown of Aeration Air Blowers for Electricity Cost Savings

December 8, 2010December 8, 2010

Representing 40 to 60% of a Typical Wastewater Representing 40 to 60% of a Typical Wastewater p g ypp g ypTreatment Plant’s Electrical Energy Use, Diffused Treatment Plant’s Electrical Energy Use, Diffused Aeration Air Blowers (and Turndown Thereof) Aeration Air Blowers (and Turndown Thereof) P id P i F f E S iP id P i F f E S iProvide a Primary Focus for Energy SavingsProvide a Primary Focus for Energy Savings

Misc. Electricity

Uses

Misc. Electricity Uses

Diffused A tiRAS/WAS

Solids Handling/

Processing

Uses

RAS/WAS

Solids Handling/Processing

Aeration

Channel Aeration

RAS/WAS PumpingDiffused

AerationChannel Aeration and/or

Mixing

Pumping

and/or MixingRaw Sewage/Effluent

Pumping

Plants with Raw Sewage/Effluent Pumping

Plants without Raw Sewage/Effluent Pumping

The Diurnal Dry Weather Flow Pattern of MostThe Diurnal Dry Weather Flow Pattern of MostThe Diurnal Dry Weather Flow Pattern of Most The Diurnal Dry Weather Flow Pattern of Most WWTPs Presents the Opportunity for TurndownWWTPs Presents the Opportunity for Turndown

2,650 hp of BlowerCapacity in UseCapacity in UseUnder Both Flow

Conditions

Diurnal Min to Max Ratio = 42/77=55%

If 2,650 hp Can Handle 77 mgd

Then (0.55)(2650) hp or 1,458 hpShould Handle 42 mgd

Historical Dry Weather Diurnal Flow PatternFor the San Antonio Water Systems Dos Rios WRF

Diffused Aeration System Energy Use is HighlyDiffused Aeration System Energy Use is HighlyDiffused Aeration System Energy Use is Highly Diffused Aeration System Energy Use is Highly Influenced by Blower TypeInfluenced by Blower Type

Silencer

To Other A ti To Other A ti

M

PIT

Aeration BasinsAeration Basins

Aeration BasinAeration BasinRunningStartingStopped

RunningStartingStopped

FIT M AIT

Single-Stage Centrifugal Single-Stage Centrifugal

StoppedStartStop

StoppedStartStop

Start/Stop Start/Stop M M BlowerBlowerStart/Stop

StationStart/Stop

StationM M

Multi-Stage Centrifugal Blower

Positive Displacement Blower

High-SpeedTurbo Blower

Turndown of MultiTurndown of Multi--Stage Centrifugal BlowersStage Centrifugal Blowers

Inlet (Suction) Valve( )Throttling

Speed ControlVia Variable Frequency Drive

Images Courtesy of HSI

Comparison of Blower Turndown Techniques: InletComparison of Blower Turndown Techniques: InletComparison of Blower Turndown Techniques: Inlet Comparison of Blower Turndown Techniques: Inlet Valve Throttling Valve Throttling versusversus VFD ThrottlingVFD Throttling

3560 (RPM)3560 (RPM)

Design Condition8000 ICFM @ 8.5psig

(63% Open)

3480 (RPM)3480 (RPM)

3190 (RPM)3190 (RPM)

3030 (RPM)3030 (RPM) (63% Open)

(42% Open)(32% Open)

( )( )

10HP

Legend73HP

75HP

Full Speed/Un-throttledCharacteristicsInlet Valve ThrottledThrottled Characteristics

VFD ThrottledCharacteristics

Estimating the Simple Payback on a VFDEstimating the Simple Payback on a VFDEstimating the Simple Payback on a VFD Estimating the Simple Payback on a VFD Investment for Blower TurndownInvestment for Blower Turndown

InstantaneouskW Savings

InstantaneousHP Savings

kW Savings

Estimating the Simple Payback on a VFDEstimating the Simple Payback on a VFDEstimating the Simple Payback on a VFD Estimating the Simple Payback on a VFD Investment for Blower TurndownInvestment for Blower Turndown

Daily Energy Savings Over and y gy g

Above Inlet Value Throttling …… 923 kWh

Annual Energy Savings ………….. 337,000 kWh

Annual Electricity CostAnnual Electricity Cost

Savings @ $0.09/kWh …………… $30,300

Cost of 400-HP VFD (Installed)……$50,000

S 1 65 Y$50,000( )Simple Payback …… 1.65 Years$30,300( )

Turndown of SingleTurndown of Single--Stage Centrifugal BlowerStage Centrifugal BlowerEfficient Turndown when Used Aloneas Long as Inlet Temperature and Pressures Remain Relatively Constant

Discharge Diffuser Vanes

All T d h U d AlAllows Turndown when Used AloneUnder Varying Inlet Temperatureand Pressure Conditions Images Courtesy of Turblex Inc.

A Siemens CompanyInlet Guide Vanes

Comparison of Comparison of Blower TurndownBlower TurndownBlower Turndown Blower Turndown Techniques: Single Techniques: Single Vane Throttling Vane Throttling VersusVersus Dual Vane Dual Vane ThrottlingThrottling

100 to 40% Turndown

125 HPDesign Condition35,000 ACFM @ 10psig

140 HP

Legend

Single VaneThrottledCh t i tiCharacteristicsDual Vane Throttled Characteristics

Estimating the Simple Payback on a Dual VaneEstimating the Simple Payback on a Dual VaneEstimating the Simple Payback on a Dual Vane Estimating the Simple Payback on a Dual Vane Investment for Blower TurndownInvestment for Blower Turndown

InstantaneouskW Savings

InstantaneousHP Savings

kW Savings

Estimating the Simple Payback on a Dual VaneEstimating the Simple Payback on a Dual VaneEstimating the Simple Payback on a Dual Vane Estimating the Simple Payback on a Dual Vane Investment for Blower TurndownInvestment for Blower Turndown

Daily Energy Savings Over and AboveDaily Energy Savings Over and Above Single Vane Throttling …………………………….2,371 kWh

Annual Energy Savings…………………………865,000 kWh

Annual Electricity Cost Savings @ $0.09/kWh ……………………………….…………$77,900@ ,

Incremental cost of dual vane 35,000/10-psig/2,000-HP single-stage centrifugal blower …………$100,000

Simple Payback …………………… 1.28 Years$100,000$77,900( )

Effect ofEffect of NotNot Turning Down the Dos Rios WRFTurning Down the Dos Rios WRFEffect of Effect of NotNot Turning Down the Dos Rios WRF Turning Down the Dos Rios WRF BlowersBlowers

Hour of the Day Observed Flow (mgd)

% of Max Day Avg. (%)

Required Aeration HP

Excess Aeration HP

Excess Aeration kWh

1:00 AM 68 89 2,370 280 2092:00 AM 66 87 2,300 380 2613:00 AM 64 84 2,230 420 3134:00 AM 58 76 2,020 630 4705:00 AM 53 70 1,850 800 5976:00 AM 48 63 1,670 980 7317:00 AM 46 61 1,600 1,050 7838 00 AM 44 58 1 530 1 120 8358:00 AM 44 58 1,530 1,120 8359:00 AM 41 54 1,430 1,220 910

10:00 AM 46 61 1,600 1,050 78311:00 AM 50 66 1,740 910 67912:00 PM 58 76 2,020 630 4701:00 PM 65 86 2 270 380 2831:00 PM 65 86 2,270 380 2832:00 PM 71 93 2,480 170 1273:00 PM 75 99 2,620 30 224:00 PM 75 99 2,620 30 225:00 PM 75 99 2,620 30 226:00 PM 75 99 2,620 30 22,7:00 PM 76 100 2,650 0 08:00 PM 74 97 2,580 70 529:00 PM 72 95 2,510 140 104

10:00 PM 69 91 2,410 240 17911:00 PM 67 88 2,340 310 23112:00 AM 69 91 2,410 240 179

Excess kWh Used Daily = 8,285

Excess Electricity Cost Incurred Daily @ $0.046/kWh = $381 or $139,000/year

Closed Loop D O Controlled Algorithm for BlowerClosed Loop D O Controlled Algorithm for BlowerClosed Loop D.O. Controlled Algorithm for Blower Closed Loop D.O. Controlled Algorithm for Blower TurndownTurndown

4.8 7.24.8 7.2160 240 40 6040 604000 6000 0.8 1.240 6040 60 4.8 7.29.6

120

2.44.8 7.2

9.6

120

2.4

0

80

160 240

320

400

Blower Air and Air Valve

Control Signal to Other

Blower Air and Air Valve

Control Signal to Other

Diffused Air Flow

Diffused Air Flow

Dissolved Oxygen

Dissolved Oxygen

Diffused Air Valve Position

Diffused Air Valve Position

0

20 80

1000

20 80

1000

2000

000 6000

8000

10000 20

0.4

0.8 1.2

1.6

Motor AmpsMotor Amps

Header PressureHeader

PressureInlet Guide

Valve Position

Inlet Guide Valve

Position

0

20 80

1000

20 80

100

to Other Basins

to Other Basins

Filter/ Silencer

PositionPosition

Dissolved Oxygen Signal Averager /Dissolved Oxygen Signal Averager /

AY

M

PIC PIT AY

MFITRunningStartingStoppedStart

RunningStartingStoppedStart

Signal Averager / DiscriminatorSignal Averager / Discriminator

AIT AIT AITFIT AIT AIT AIT



11.0 12.0

11.5

0 10000

5000

0 4

2

AICFIC SwitchStopStop FIC Switch AIC

11.0

11.5

12.0 0

5000

10000 0

2

4Representative or

“Pacing” Aeration BasinRepresentative or

“Pacing” Aeration Basin0

Dissolved O2Setpoint

Dissolved O2Setpoint

Air Flow SetpointAir Flow Setpoint

Pressure SetpointPressure Setpoint

The Reliability of the D.O. Process Variable Can BeThe Reliability of the D.O. Process Variable Can BeThe Reliability of the D.O. Process Variable Can Be The Reliability of the D.O. Process Variable Can Be Enhanced Through the Use of Redundant Enhanced Through the Use of Redundant Instrumentation and Output Signal Discrimination Instrumentation and Output Signal Discrimination FiltersFilters

Raw Sewage Flow Controlled Algorithm for BlowerRaw Sewage Flow Controlled Algorithm for BlowerRaw Sewage Flow Controlled Algorithm for Blower Raw Sewage Flow Controlled Algorithm for Blower TurndownTurndown

ZIZIHCHC

Inlet Guide Vane Position Indicator (36

to 100% Open)Ratio Station

ZIZIHCHC

Existing Inlet Guide Vane Position Controller Located on Blo er

SV1 PV2

RatioRatio

PV3(4-20 mA, Where 4

A 36% O )

Located on Blower Control Panel

( PV1) ( X.X) = PV2Where X.X = 0.5 to 2.0

PV1

PV2 = SV2(4-20 mA)

HCHC

FITFITZCZC ZITZIT

mA= 36% Open)

Ambient Air

MM 1200 t 3000 HP

PV1(4-20 mA, Where 4 mA = 0 mgd and 20 mA =

Span)

MV(4-20 mA, Where 4 mA= 36% Open)

Raw Sewage

FEFE MMMM

Aeration Inlet Guide

Vanes

≈1200 to 3000 HP

To Blower Discharge Header

FEFEAeration Blower

Vanes

108” Influent Flow Meter

A Simple Relationship Table for Blower TurndownA Simple Relationship Table for Blower Turndown

Hour of the Day Observed Flow (mgd)

Blower Guide Vane Position (%)

1:00 AM 68 602:00 AM 66 603 00 AM 64 83:00 AM 64 584:00 AM 58 585:00 AM 53 506:00 AM 48 507:00 AM 46 508:00 AM 44 458:00 AM 44 459:00 AM 41 4510:00 AM 46 5011:00 AM 50 5012:00 PM 58 581:00 PM 65 581:00 PM 65 582:00 PM 71 653:00 PM 75 804:00 PM 75 805:00 PM 75 806:00 PM 75 807:00 PM 76 808:00 PM 74 709:00 PM 72 7010:00 PM 69 6511:00 PM 67 6012:00 AM 69 65

Closed Loop D.O. Control Optimizes Energy UseClosed Loop D.O. Control Optimizes Energy Use

0

20004000 6000

8000

10000 20

0.4

0.8 1.2

1.64.8 7.2

9.6

120

2.44.8 7.2

9.6

120

2.4

0

2040 60

80

1000

2040 60

80

1000

2040 60

80

1000

2040 60

80

1000

60120 180

240

3000

60120 180

240

3000

2040 60

80

1000

2040 60

80

1000

16003200 4800

6400

80000

16003200 4800

6400

80000

2040 60

80

1000

2040 60

80

100

Inlet Guide Inlet Guide Vane PositionVane Position

Blower Blower SpeedSpeed

Diffuser Vane Diffuser Vane PositionPosition

Motor Motor AMPsAMPs

Header Header PressurePressure

BlowBlow--Off Off Valve Valve

PositionPosition

Diffused Air Diffused Air FlowFlow

Dissolved Dissolved OxygenOxygen

Diffused Air Diffused Air Valve Valve

PositionPosition

SilencerSilencerPIT To Other To Other

M

MFITRunningRunningStartingStarting

To Other To Other Aeration Aeration BasinsBasins

AIT

Aeration BasinAeration Basin

SingleSingle--Stage Stage Centrifugal Centrifugal

AICFIC

StoppedStoppedStartStartStopStop

PIC

8 12

10

0 10000

5000

0 2

1

Centrifugal Centrifugal BlowerBlowerM

PICMM

Dissolved Dissolved OO22 SetpointSetpoint

Air Flow Air Flow SetpointSetpoint

Pressure Pressure SetpointSetpoint

Increasing D.O. Demand

EquilibriumReached

Closed Loop D.O. Control Optimizes Energy UseClosed Loop D.O. Control Optimizes Energy Use

0

20004000 6000

8000

10000 20

0.4

0.8 1.2

1.6

0

2040 60

80

1000

2040 60

80

100 0

16003200 4800

6400

80000

16003200 4800

6400

8000 0

2040 60

80

1000

2040 60

80

100 0

60120 180

240

3000

60120 180

240

300 0

2040 60

80

1000

2040 60

80

100

4.8 7.29.6

120

2.44.8 7.2

9.6

120

2.4

0

2040 60

80

1000

2040 60

80

100







PositionPosition

Diffused Air Diffused Air FlowFlow

Dissolved Dissolved OxygenOxygen


PositionPosition

SilencerSilencerPIT To Other To Other

M

MFITRunningRunningStartingStarting

To Other To Other Aeration Aeration BasinsBasins

AIT



AICFIC


PIC

8 12

10

0 10000

5000

0 2

1


PICMM

Dissolved Dissolved OO22 SetpointSetpoint

Air Flow Air Flow SetpointSetpoint


Decreasing D.O. Demand

EquilibriumReached

You Can’t Change the Laws of PhysicsYou Can’t Change the Laws of Physics

Blower ShaftHorsepower ~

Mass FlowProduced

Pressure BuildAcross the Blower( )

( )( )( )Horsepower Efficiency of the

Blower

( ) ( )Bl S l i dBlower Selection and Turndown Mechanism

Dependent

Optimized UsingClosed-Loop Dissolved

O C t l

Optimized Using Most O V l H d

Oxygen Controls

Open Valve Header Pressure Controls

CharacteristicCharacteristic HeadlossHeadloss Across Throttled ButterflyAcross Throttled ButterflyCharacteristic Characteristic HeadlossHeadloss Across Throttled Butterfly Across Throttled Butterfly ValveValve

Most Open Valve Header Pressure Control Also Optimizes Most Open Valve Header Pressure Control Also Optimizes Energy UseEnergy Usegygy

0

16003200 4800

6400

80000

16003200 4800

6400

80000

2040 60

80

1000

2040 60

80

100 0

2040 60

80

1000

2040 60

80

100 0

60120 180

240

3000

60120 180

240

300 0

2040 60

80

1000

2040 60

80

100

4.8 7.29.6

120

2.44.8 7.2

9.6

120

2.4

0

2040 60

80

1000

2040 60

80

100 0

2040 60

80

1000

2040 60

80

100







PositionPosition


PositionPosition


PositionPosition

SilencerSilencerMFITPIT AIT

MSTEP 1: Find Most Open Valve UsingDiffused Air Valve Position SignalsSTEP 2: If Any Valve is Greater ThanLimit Setpoint; Increase Header PressureSTEP 3: If Any Valve is Less ThanLimit Setpoint; Decrease Header Pressure

RunningRunningStartingStarting




PIC

FIND

IF MFIT AIT

8 12

10

0 100

50


PICMM

IF MFIT AIT


Most Open Valve Most Open Valve Limit Limit SetpointSetpoint


Most Open Valve Header Pressure Control Also Optimizes Most Open Valve Header Pressure Control Also Optimizes Energy UseEnergy Usegygy

0

2040 60

80

1000

2040 60

80

100 0

16003200 4800

6400

80000

16003200 4800

6400

8000 0

2040 60

80

1000

2040 60

80

100 0

60120 180

240

3000

60120 180

240

300 0

2040 60

80

1000

2040 60

80

100

4.8 7.29.6

120

2.44.8 7.2

9.6

120

2.4

0

2040 60

80

1000

2040 60

80

100 0

2040 60

80

1000

2040 60

80

100







PositionPosition


PositionPosition


PositionPosition

SilencerSilencerMFITPIT AIT

M

RunningRunningStartingStarting




PIC

FIND

IF MFIT AIT

8 12

10

0 100

50


PICMM

IF MFIT AIT


Decreasing

Most Open Valve Most Open Valve Limit Limit SetpointSetpoint


HeaderPressure

Case Study: Jacksonville, IL WWTPCase Study: Jacksonville, IL WWTP• Current condition: Continuous operation of 1 out of 4 multistage centrifugal blowers (four @ 300 HP)

No VFDs Inlet valve throttled at 50% 44% of total WWTP• No VFDs, Inlet valve throttled at 50%, 44% of total WWTP electricity use

• Energy use evaluation provided two recommendations toEnergy use evaluation provided two recommendations to improve efficiency:

• Automated control of inlet valve throttling by either a dissolved oxygen or raw sewage flow control loop

• Installation of a high speed turbo-type centrifugal blower

Condition

Average Daily

Electricity Use (kWh)

% Daily Energy Savings

Energy Savings per Year (kWh)

Energy Cost

Savings per Year

Estimated Installation Cost / Calculated Simple

Payback Period (years)

Existing Blowers 4,300 - - - -

Existing Blowers with Increased Levels of Inlet

Valve Throttling3,400 21% 329,000 $26,000 $40,000 / 1.6

Valve Throttling

New High Speed Turbo-type Blower with

Onboard VFD2,200 49 % 767,000 $61,000 $250,000 / 4.1

Case Study: Valparaiso, IN WWTPCase Study: Valparaiso, IN WWTP• Current condition: Continuous operation of 1 out 4 multistage centrifugal blowers (two @ 200HP & two @ 400HP)

No VFDs Inlet valve throttled at 50% 40% of total WWTP• No VFDs, Inlet valve throttled at 50%, 40% of total WWTP electricity use

• Energy use evaluation provided recommendations to improveEnergy use evaluation provided recommendations to improve efficiency:

• Add VFDs on existing two 200-HP blowers

• Modify blower impellers to allow for maximum turndown

Average % Daily Energy Energy Estimated Installation CostCondition Daily




Cost Savings per

Year




Existing Blowers modified w/new

impellers and VFDs 2,500 31 % 402,000 $32,000 $200,000/6.25

Case Study: Marion, IN WWTPCase Study: Marion, IN WWTP• Current condition:

•Three 300HP PD blowers operating with VFDs (blowers are 30 to 40 years old)

•One blower is typically operated at 60% speed (3000 SCFM)

• Recommendation: • Based on energy use analysis of existing blowers, a high speed turbo-type centrifugal blower was recommendedyp g

Average % Daily Energy Energy Estimated Installation CostCondition Daily




Cost Savings per

Year




New High Speed Turbo-type Blower with

Onboard VFD2,100 34 % 402,000 $32,000 $250,000/7.8

ConclusionConclusionTurndown of aeration air blowers yields real cost savings:

SAWS/Dos Rios WRF realized > $125,000/yearDallas/Southside WWTP realized > $880,000/year

Effective turndown requires:

Appropriate selection of turndown mechanismturndown mechanism

Optimized use of oxygen

Optimized use of

pressure

$$ Saved

Thank YouThank YouThank YouThank You

Questions &Questions &AnswersAnswers

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