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
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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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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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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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I Sit C li W t C it M tIn-Situ Cooling Water Capacity Measurement
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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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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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Impeller-Diffuser CFD Studyp yNew Design for Upgrade
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I ll Diff CFD St dImpeller-Diffuser CFD Study
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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
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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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~ 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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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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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
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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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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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