The effects of paint-based protective films on the actual temporal water-side performance ...

187 Pages·2017·10.91 MB·English

by  Information Technology

The effects of paint-based protective films on
the actual temporal water-side performance
characteristics of steam surface condenser
tubes
by
John Goodenough
Dissertation presented for the degree of Doctor of Philosophy in the
Faculty of Engineering at
Stellenbosch University
Supervisor: Prof Hanno Carl Rudolf Reuter
Co-supervisor: Dr Mike Owen
March 2017
Stellenbosch University https://scholar.sun.ac.za
Declaration
By submitting this dissertation electronically, I declare that the entirety of the
workcontainedthereinismyown,originalwork,thatIamthesoleauthorthereof
(savetotheextentexplicitlyotherwisestated),thatreproductionandpublication
thereofbyStellenboschUniversitywillnotinfringeanythirdpartyrightsandthat
Ihavenotpreviouslyinitsentiretyorinpartsubmitteditforobtaininganyqual-
ification.
Date: ..............M..a.r.c.h. 2.0..1.7...........
Copyright©2017StellenboschUniversity
Allrightsreserved.
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Abstract
Paint-based protective films (PPFs) are applied to the internal surface of steam
surface condenser tubes to mitigate corrosion and erosion. The performance
impactresultingfromfresh-waterfoulingonthesePPFsisexperimentallyinves-
tigatedusingactualcoolingwaterfromathermalcoal-firedpowerstation. Four
different paint types are tested alongside unmodified stainless steel, titanium,
andbrasstubesfordirectcomparison,usingapurpose-builttestapparatusfea-
turingsixco-currentflowdouble-pipeheatexchangersarrangedinparallel. Ex-
posure times vary between 85 days and 280 days providing novel information
pertainingtothesePPFsintermsoftheirperformanceovertime.
Coolingwaterexitingthecondenserisdrawnfromatake-offvalvefittedbe-
forethecoolingductentersthewet-cooledcoolingtower,andpassesthroughthe
testapparatusat4L/s. Thecoolingwaterpassesoncethrougheachtesttubeat
thecondenserdesignvelocitybeforebeingreturnedtothecoolingtowerpond.
Each tube is heated using water instead of steam, to provide consistent and re-
peatableouterconvectionconditions. Bymeasuringatotalof24bulkfluidtem-
peraturesand12volumetricflowrates,theheattransfer,andhencefoulingfac-
tor,foreachtubeisdeterminedduringtests.
In order of decreasing predominance: biological fouling, precipitation foul-
ing (scaling), and particulate fouling (deposition) are identified on all the test
tubes. The unmodified admiralty brass tube provides the best overall perfor-
mancebecauseitscopperionsretardthebiologicalfoulingrate.Thenon-biocidal
PPFs experience similar fouling to all the non-copper alloy tubes tested, where
their asymptotic fouling factors are almost five times greater than the copper-
bearing alloy tested. The data gained using the testing techniques described
hereinallowsthedominantfoulingmechanismtobeidentifiedandcanbeused
to better design water treatment management, as well as direct further PPF de-
velopment towards reducing biological fouling tendencies. One of the biocidal
PPFs that is tested reaches a lower fouling factor than an unmodified stainless
steeltubeafter85daysofexposureunderthesameconditions. Theseresultsare
comparedtotheplant’scondenserfoulingfactor,calculatedusingaonedimen-
sionalcondensermodel.Theagreementbetweenthefoulingfactormeasuredon
single tubes compared to the fouling factor of the condenser validates the test-
ing and further means that the fouling data can be used to enhance condenser
designandmanagementusingPPFs.
Keywords: Paint,coating,condenser,fouling,biofouling,performance,corrosion,thermal
conductivity
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Uittreksel
Verf-gebaseerdebeskermendefilm(VBF)wordtoegepasaaninterneoppervlak-
tes van stoom oppervlakte kondenser buise om roes te versag. Die prestasie
impak gevolg van vars-water aangroei op die VBF is eksperimenteel ondersoek
deurgebruikvanwerklikeverkoelingswatervantermiesesteenkoolkragstasie.
Vier verkillende verf tiepes word getoets langs onveranderde vlekvrye staal, ti-
tanium en koper buise vir direkte vergelyking, deur gebruik van doel-geboude
toets aparatus wat ses mede-huidige vloei dubbel pyp hitte uitruilers uitgele in
parallel. Blootstellingtyekanverskiltussen85daeen280daeverskafuniekein-
formasiemetbetrekkingtotdieVBFintermevandieprestasieoortydterwyldie
onderwerpvandieindentiesewaterwatindienservaarword.
Verkoelingswaterwatdiekondenserverlaat,wordvertrekvan’nuitlaatklep
wattoegerusisvoordieverkoelingsuitlaatpypdienat-verkoeldeverkoelingstor-
ing in loop, en loop deur die toets aparatus teen 4L/s. Die verkoelings water
loop een keer deur elke toets buis van die kondenser ontwerpde snelheid voor
ditteruggekeerwordnadieverkoelingstoringdam. Elkebuisisverhitdeurwa-
terinplaasvanstoom,om’nkonstanteenvertroubarebuitekonveksietoestand
tevoorsien.Deur’ntotaalvan24grootmaatvloeistoftemperatureen12volume-
triesefloeikoers,diehitteoordrag,envandaardieaangroeifaktorvanelkebuis
wordbepaalgeduirendedietoets.
Biologieseaangroei,skalering,endeeljies(ingesteldheid)wordgeidentifiseer
asdieoorheersendemeganismeopaldietoetsbuise,hoeweldieonveranderde
Admiralty braas buise voer die beste algehele prestasie want die koper ione be-
woonbakterelesellulereasemhaling.Dienie-biocidenVBFervaringhetsoortge-
lykaangroeiviraldienie-koperallooibuisewatgetoetswas, waarhulleasimp-
totiese aangroei faktore in orde was vyf keer groter as die koper-draende allooi
wat getoets was. Die data laat toe dat die dominante aangroei meganisme gei-
dentifiseer word en dan beter gebruik kan word vir beter ontwerpde water be-
handelingbeheer,sowelasdirekverdereVBFontwikkelingvirdievermindering
vanbiologieseaangroeineigings. EenvandiebiocidenVBFwatgetoetswas,het
’n laer biologiesie aangroei bereik as ’n nie geverfde stainless steel buise na 85
daeonderdieselfdeblootstelling. Hierdieresultateisvergelykmetdiekragstasie
sekondenseraangroeifaktor,watbepaalisdeur’neendimensionellekondenser
model. Dieooreenkomstussendieaangroeifaktorwatgemeetisopenklebuise
invergelykingvandieaangroeifaktorvandiekondenserbevestigdietoets,endie
datakandusgebruikwordvirdieverbeteringvankondenserontwerpenbestuur,
deurdiegebruikvanVBF.
Sleutelwoorde:verf,laag,kondenser,aangroei,biologieseaangroei,pre,roes,gradering,ter-
miesegeleiding
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Acknowledgements
MydeepestgratitudeisgiventomysupervisorandmentorProfessorHannoCarl
Rudolf Reuter. Thank you for your continued dedication, exceptional support,
andleadershipthroughouttheyearsofourfriendship. Yourteachingisextraor-
dinaryandIshallalwaysendeavortoapplytheknowledgeyouhavepassedonto
me.
MyparentshavemadethisprojectpossibleandIcouldnothaveachievedany
ofthiswithoutthem.Myfatherhasguidedmealonganamazingjourney,lighting
the way ahead. Thank you for believing in us and never giving up. My mother,
with her ironclad faith in all our efforts, has been a stronghold in any adversity.
To my sister and brother-in-law, thank you and I appreciate your never-ending
help,encouragementandsupport.
Membersofthepowerutilitywhowereinstrumentalinthisresearcharedeeply
appreciated. In particular Dhiraj Maharaj, the plant station manager who sup-
portedthisprojectfromitsinception.LouwNagal,KeithNorthcott,Kelley-Reynolds
Clausene,FrancoisdePreez,AlainMicheals,andGontseMathibediareexpressly
thankedfortheircontributions.
Tomyco-supervisorDrMichealOwen,thankyouforyourexceptionalguid-
ance,aswellasyourdeterminedsupportinseeingthisprojecttocompletion.
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Contents
Page
Declaration i
Abstract ii
Uittreksel iii
Acknowledgements iv
Contents v
Listoffigures viii
Listoftables x
Nomenclature xiii
1 Introduction 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Foulingofheattransfersurfaces . . . . . . . . . . . . . . . . . . . . . 6
1.3 Fieldtestingofthewatersidefoulingofcondensertubesatather-
malpowerplant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.4 Definitionsandpresuppositions . . . . . . . . . . . . . . . . . . . . 12
1.5 Contextofthisresearch . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.6 Researchobjectivesandmotivation . . . . . . . . . . . . . . . . . . 13
1.7 Thesisoutline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2 Literaturesurvey 17
2.1 Characteristicsofcondensertubematerials . . . . . . . . . . . . . . 17
2.2 PerformancetestingofPPFsinheatexchangerapplications . . . . 20
2.3 Foulingmitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.4 Measuringthefoulingresistance . . . . . . . . . . . . . . . . . . . . 26
2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3 Experimentation 32
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.2 Apparatusdescription . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
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CONTENTS
3.3 Measurementtechniques . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.4 Operationandcontrol. . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.5 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.6 Performancemeasures: thefoulingfactorandcleanlinessfactor . 49
3.7 Foulingmodeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.8 Calibrationandvalidation . . . . . . . . . . . . . . . . . . . . . . . . 52
3.9 Uncertaintyanalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
3.10 Dataprocessing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
3.11 Experimentalresults . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
3.12 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
4 Relatingtheexperimentalresultsobtainedonsingletesttubestothe
actualcondenserperformance 79
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
4.2 Theoryforcondensationonasinglehorizontalcondensertube . . 80
4.3 Condensationphenomenainsideasteamsurfacecondenser . . . 81
4.4 Designperformancefactor . . . . . . . . . . . . . . . . . . . . . . . . 82
4.5 Actualcondenserperformance . . . . . . . . . . . . . . . . . . . . . 85
4.6 ImpactonthecondenserperformanceandPPFsinthecondenser
lifecycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
5 Conclusionsandrecommendations 94
5.1 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
5.2 Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Listofreferences 98
Appendices 106
A Thermophysicalpropertydata 107
A.1 Thermophysicalpropertiesofsaturatedwater . . . . . . . . . . . . 107
A.2 Thermophysicalpropertiesofsaturatedwatervapor . . . . . . . . 108
B Supplementarydataandphotographs 109
B.1 Testfacilityspecifications. . . . . . . . . . . . . . . . . . . . . . . . . 109
B.2 Supplementaryphotographs . . . . . . . . . . . . . . . . . . . . . . . 109
C Calibrationsandcommissioningtests 114
C.1 Temperatureprobecalibrationandcertification . . . . . . . . . . . 114
C.2 Regressioncoefficientsresultingfromtheannularconvectionco-
efficienttesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
C.3 Conductivities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
C.4 Flowmeteringcalibrationresults . . . . . . . . . . . . . . . . . . . . 128
C.5 ComparisonofannularNusseltnumbers . . . . . . . . . . . . . . . 129
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CONTENTS
D Experimentaldata 130
D.1 Presentationofdata . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
D.2 Rawdata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
D.3 Processedconvectiondata . . . . . . . . . . . . . . . . . . . . . . . . 147
D.4 AnnularNusseltnumbers . . . . . . . . . . . . . . . . . . . . . . . . 150
D.5 Heattransferdata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
D.6 Bacterialcounts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
D.7 ComparisonofR andR fromtestBandtestC . . . . . . . . . . 161
f f∗
E Samplecalculations 162
E.1 Determiningthefrictionfactoratthestartoftesting . . . . . . . . . 162
E.2 Determiningthefoulingfactor . . . . . . . . . . . . . . . . . . . . . 164
F Wateranalysis 170
F.1 Coolingwateranalysis . . . . . . . . . . . . . . . . . . . . . . . . . . 170
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List of figures
Page
1.1 Temperature-entropydiagramoftheRankinepowercycle . . . . . . . 2
1.2 Simplifiedendviewofcondenser . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Crosssectionofcondensertube . . . . . . . . . . . . . . . . . . . . . . . 5
1.4 Schematicofanopenrecirculatingcoolingsystemwithawet-cooled
naturaldraftcoolingtower . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.5 Influence of bulk water temperature: measured log rate of biofilm
thicknessinanexperimentalflowsystem . . . . . . . . . . . . . . . . . 9
1.6 TimelineofthehistoryofPPFsusedattheselectedthermalpowerplant 11
2.1 Overallheattransfercoefficientchangewithtimeforseveralcondenser
tubealloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.2 Schematicofpilotplant . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.1 Apparatusinstallationinrelationtotheplantcoolingwaternetwork . 33
3.2 Illustrationcomparingheattransferconditionswithinthecondenser
andthedouble-pipeheatexchanger . . . . . . . . . . . . . . . . . . . . 34
3.3 Photographoftheapparatushousing . . . . . . . . . . . . . . . . . . . . 35
3.4 Simplified front view of the apparatus showing hexagonal arrange-
mentoftheheatexchangers . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.5 Photographs showing a centralizing disc inside the heat exchanger
unionatitsmidpoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.6 Explodedviewofatubegland . . . . . . . . . . . . . . . . . . . . . . . . 36
3.7 Pipingandinstrumentationdiagramshowingvariablemeasurement
locationsandset-pointflowrates . . . . . . . . . . . . . . . . . . . . . . 38
3.8 Perspectiveviewofheatexchangers. . . . . . . . . . . . . . . . . . . . . 39
3.9 Photographshowingastaticpressuretapping . . . . . . . . . . . . . . . 41
3.10 Schematicofaheatexchanger . . . . . . . . . . . . . . . . . . . . . . . . 46
3.11 Diagramshowingthelinkpipeinstalledduringnoloadtesting . . . . 52
3.12 Measuredflowratesusingtheultrasonicflowmetercomparedtothe
referenceelectromagneticflowmeter . . . . . . . . . . . . . . . . . . . . 53
3.13 Flowchartshowingtheexperimentalprocedure . . . . . . . . . . . . . 56
3.14 MeasuredfrictionfactorsfromtestA . . . . . . . . . . . . . . . . . . . . 61
3.15 MeasuredfoulingfactorsfromtestA . . . . . . . . . . . . . . . . . . . . 62
3.16 PhotographofTT3Aafterlongitudinalsectioning . . . . . . . . . . . . 63
3.17 MicrographofTT3Aaftercrosssectioningshowingdezincification . . 63
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LISTOFFIGURES
3.18 Measuredfoulingfactorscomparedusingequations(3.24)and(3.30). 64
3.19 MeasuredfrictionfactorsfromtestB . . . . . . . . . . . . . . . . . . . . 66
3.20 BulkfoulingfluidvelocityfromtestB . . . . . . . . . . . . . . . . . . . . 67
3.21 MeasuredfoulingfactorsfromtestB . . . . . . . . . . . . . . . . . . . . 68
3.22 CleanlinessfactorversustimemeasuredduringtestB . . . . . . . . . . 70
3.23 Bacterialcountsafter126daysofexposure . . . . . . . . . . . . . . . . 71
3.24 QEMSCAN®cross-sectionalmicrographsofstainlesssteeltubes:TT1B
andTT2B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
3.25 QEMSCAN®cross-sectionalmicrographsoftitaniumtubes:TT4Band
TT5B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
3.26 Dwelltimesnecessaryforremovaloffoulantsoneachtubeusinghigh
pressurewaterlancing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
3.27 MeasuredfrictionfactorsfromtestC . . . . . . . . . . . . . . . . . . . . 75
3.28 MeasuredfoulingfactorsfromtestC . . . . . . . . . . . . . . . . . . . . 76
3.29 CleanlinessfactorversustimemeasuredduringtestC . . . . . . . . . . 77
4.1 Simplifiedillustrationofthesteam-waterpowercycleusedbythepower
plant(designvaluesnormalizedper1MW ) . . . . . . . . . . . . . . . . 80
e
4.2 Performancefactorasafunctionofsteamflow . . . . . . . . . . . . . . 84
4.3 Estimatedfoulingfactoroftheplantcondenser . . . . . . . . . . . . . . 85
4.4 Modelcomparisontoactualplantdata . . . . . . . . . . . . . . . . . . . 86
4.5 CleanlinessfactoroftheplantcondensercomparedtotesttubeTT1B 87
4.6 Comparisonoftheexpectedsteamtemperatureforvarioustubeoptions 89
4.7 Measuredhotwelltemperature . . . . . . . . . . . . . . . . . . . . . . . 90
4.8 DecisiontreeforwhentoapplyPPFsinthecondenserlifecycle . . . . 91
B.1 Assembledheatexchangersbeforeplacementinthecontainer . . . . 110
B.2 Hotpumpshowingallwettedpartsareplastic . . . . . . . . . . . . . . 110
B.3 Photographduringinitialconstructionofapparatusshowingthesize
ofthecontainer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
B.4 Transportofapparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
B.5 Apparatusafterinstallationon-site . . . . . . . . . . . . . . . . . . . . . 112
B.6 Photographofblockedstrainer . . . . . . . . . . . . . . . . . . . . . . . 112
B.7 Y-strainersarrangedinparalleltoenableonlinecleaning . . . . . . . . 113
C.1 MeasuredNusseltnumbersversustheoreticalvalues . . . . . . . . . . 129
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