Upgrading a Set of Large Cooling Water Pumps with C 13the Aim to Increase Capacity at Least 13 Percent and

Minimize Impeller Cavitationp

Frank Visser

Flowserve FSG Pumps

Case Study

27TH International Pump Users Symposium, Houston, Texas, USA September 12 – 15, 2011

186

C t tContents

• Backgroundac g ou d

• In-situ capacity measurement

I ll diff CFD t d• Impeller-diffuser CFD study

• Scaled model testing

• Start-up transient

• As built performance• As built performance

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187

B k dBackground

• Up-rate of Nuclear Power Station.Up ate o uc ea o e Stat o

• Increase of electrical output power required increase of cooling water capacity (> 13%)cooling water capacity (> 13%).

• Existing cooling water pumps (CWPs) are suffering from cavitation attackcavitation attack.

• CWP retrofit design objective:– Cooling water capacity increase of 13%+

– Minimize impeller cavitation

• CWP E-motor replacement (PCWP)– System start-up transient analysis

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188

B k dBackground

Four (4) CWP running in parallel feeding condenser with seawaterou ( ) C u g pa a e eed g co de se t sea ate

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189

I Sit C li W t C it M tIn-Situ Cooling Water Capacity Measurement

• Required to establish pre-upgrade baseline situationequ ed to estab s p e upg ade base e s tuat o– Total CWPs flow rate measurement

– Individual CWP’s head measurementIndividual CWP s head measurement

• Flow rate measurement with OTT-mills6 ill h i t l i b– 6 mills on a horizontal scanning bar

– 4 throughflow areas scanned (curtain wall)

– 6x14 scanning window (14 elevations)

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190

I Sit C li W t C it M tIn-Situ Cooling Water Capacity Measurement

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191

In-Situ Cooling Water Capacity Measurement

Existing Up-rate

Speed 325 r/min 325 r/minSpeed 325 r/min 325 r/min

Capacity 7.8 m3/s 275 cfs > 8.81 m3/s > 311 cfs

Head 5.7 m 18.7 ft > 7.3* m > 24.0 ft

Ns,D 127004.64

rpm, gpm, ft(-)

112004.1

rpm, gpm, ft(-)

D 56” 58” 59”Dnom 56 58 – 59

* Per quadratic scaling

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192

I ll Diff CFD St dImpeller-Diffuser CFD Study

• Geometries studied:Geo et es stud ed– Existing impeller / diffuser combination

– Retrofit impeller / diffuser combinationRetrofit impeller / diffuser combination

• ObjectiveD t i ti f b t it ti i t (BCP) NPSHi– Determination of best cavitation point (BCP) NPSHi

– Evaluate cavitation development

– Head comparison

Note: Both the existing and retrofit design have 4 impeller blades / 7 diffuser blades

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193

Impeller-Diffuser CFD Studyp yExisting Design

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194

Impeller-Diffuser CFD Studyp yNew Design for Upgrade

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195

I ll Diff CFD St dImpeller-Diffuser CFD Study

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196

I= u.. ...... ~

"C

"' Q) .c

"' +-'

~

50 --.-------.-----------r--------.-------.-------.-----------r- 250 CFD NPSHi

CFD NPSHi 200

30 150

CFD TDH Existing Design

CFD TDH @59" 20 Uprate Design 100

10 NPSHA 50

0 +-------+-------+-------~------~------~------+ 0 50000 75000 100000 125000 150000 175000 200000

Capacity, [USGPM]

I= u.. ...... ~

:I: CJ) c.. z

I ll Diff CFD St dImpeller-Diffuser CFD Study

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197

o ...... -=====o=·=5•ojo .... -;:=:=1=.jooo <ml 0.250 0 .750

S l d M d l T tiScaled Model Testing

• ObjectiveObject e– Verify hydraulic performance

• Scaled model testing• Scaled model testing– 1:4 model scale (approx. 14” test impeller)

4 1 d ti ( 1300 / i )– 4:1 speed ratio (approx. 1300 r/min)

– Existing impeller-diffuser

– Up-rate impeller-diffuser

• Existing parts reproduced on scale f 3D Ffrom 3D Faro-arm scan

• Up-rate hydraulic parts modeled

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directly in 3D CAD

198

S l d M d l T tiScaled Model Testing

• Test Loop & Test Set-up– Q, H, performance testing

– Cavitation visualization

Flow visualization window

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Flow visualization window

with impeller mounted

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S l d M d l T tiScaled Model Testing

Cavitation @ 90% duty capacity:

– Experiment

– CFD

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200

S l d M d l T tiScaled Model Testing

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201

~ u.. ......

50

40

30

10

0 50000

Full Size Performance from Scaled Model Test of Impeller & Diffuser

.. ~

~ Upgrade @ 59" & 330 r/min

-........ ' ~

~ ~ Existing@ 330 r/min

~

~ ~Up-rate Duty Existing Duty

'\ 75000 100000 125000 150000 175000 200000

Capacity, [USGPM]

St t U T i tStart-Up Transient

• Objective:Object e– Check motor capability (torque) to start the pumps

– Determine start-up time(s)Determine start up time(s)

• Entire cooling water system is modeled

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202

St t U T i tStart-Up Transient

• Start-up requirement E-motor: Sta t up equ e e t oto– 80% Voltage

– -15% Torque (tolerance per IEC 60034-1)15% Torque (tolerance per IEC 60034 1)

• Start-up scenario: P1 th P4 t t d t 60 i t l– P1 thru P4 are started at 60 sec intervals

• Initially selected motor showed problem when starting 4th

pump– P4 could not be accelerated to full speed due to insufficient motor

torquetorque

– P4 ended up running against closed (check) valve at intermediate speed

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p

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St t U T i tStart-Up Transient

Pump curve Motor speed-torque curveu p cu e oto speed to que cu e

(80% Voltage; -15% Torque)

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St t U T i tStart-Up Transient

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205

Speed Torque Pump 1 (-15% Tol) Speed Torque Pump 2 (-15% Tol)

25 350 25 350

300 300 20 20

250 250

'E 15 200 - F luid Torque 'E 15 200 - Fluid Torque z z ~ - Motor Torque

~

" " - Motor Torque " " ~ 150 - Speed ~ 150 - Speed {:.. 10 {:.. 10

100 100

5 5 50 50

0 0 0 0 0 2 4 6 8 10 60 62 64 66 68 70

Time [sec) Time [sec)

Speed Torque Pump 3 (-15% Tol) Speed Torque Pump 4 (-15% Tol)

25 350 12 200

180 300 10

20 160 250 140 8

'E 15 200 - Fluid Torque 'E 120 - Fluid Torque z z ~ ~

" - Motor Torque " 6 100 - Motor Torque " " ~ := 10 150 - Speed ~

0 ,_ 80 - Speed

4 60 100

5 2 40 50

20

0 0 0 0 120 125 130 135 140 180 182 184 186 188 190

Time [sec) Time [sec)

St t U T i tStart-Up Transient

• Issue solved by new motor with better speed-torquessue so ed by e oto t bette speed to que

Cooling water flow through condenser at start-up

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g g p

206

A B ilt P fAs Built Performance

• Final design built @ 58 1/16”a des g bu t @ 58 / 6

• Taking into account:P f i k d t li– Performance pick-up due to up-scaling

– Intake & discharge losses not being accounted for in impeller/diffuser CFDaccounted for in impeller/diffuser CFD study and scaled model testing

– System resistance line was lowered due to installing power pack (actuator) on check values less steep characteristic

Contractually required capacity increase– Contractually required capacity increase of 113%, with +3% tolerance.

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207

A B ilt P fAs Built Performance

• In-situ field performance checks tu e d pe o a ce c ec– Four pumps running

– Three pumps runningThree pumps running

• Pumps are over-performing (Q-H)P Q H b di t d– Pump Q-H above predicted curve

– System resistance curve lowered more than expectedmore than expected

– Higher condenser cooling capacity

Higher driver power but motors are– Higher driver power, but motors are not overloaded

• At the end: Everybody Happy!23

At the end: Everybody Happy!

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Thank you for your attentionThank you for your attention

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