This projec,q- cgngngeqt on adequate funding, will provide most of *re energy lor tle hospital and will include 3-4 days energy storage in piessuised hot water.
SOLAR'88
EnvironmentalImprovementThrough SolarEnergy
Proceedingsof the Annual Conference of the Australian and New 7*aland SolarEnergy Society
L7-L9Nove,mber 1988 University of Melbourne
Editor - Ken Gutbrie Thermal ProjectManager Victorian Solar EnergyCouncil 10th Floor, 270 FlindersSt. Melboume 3000
Australian and New ZealandSolar
EnergySociety
Rrblished by Auslralian and New Zn"lardsolar EnergySocisy Copyrigh 1988Ausrralian and New ?;;alardsdarEnergr Soci*y
stateoents of frct ard opinion madain articles in 6es proceedingsare tboceof tbe authrrs; all aclaowledgementsmd rcftrences in sticbs are frc resporeibility of the authors. Neitber tbe Australiao and New zcaland Solar Eo€rgr S&ty, tbc Edits ns tte Editorid comnitac "!"n u" respon*ute for irconca staementgorlibel. Advertising material in 6ese proceedingswas rcoeptedana inccporatea into tb layort by tb Editor. Endorscmcntof tbe advertiscdpro&cts-ad serrries Uy aftZSfS or ary .a;o"t urbors isnotimplied
rsBN0958852049
SOLAR'88- ANZSESCONFERENCE MELBOURNENOVEMBER1988
CAMBELLTOWN HOSPITAL STEAM PLANT UPDATE Dr D.R. Mills andDr B. Mukherjee Department of AppliedPhysics Schoolof Physics Universityof Sydney SydneyNSW 2006 MrA. Moore HOSPLAN RozelleNSW 2039 INTRODUCTION ln Augustthisyearthesolarindustrialprocess-steem plantfundedby rhe demonstration NationalEnergyResearch DevelopmentandDemonstration Program(N.E.R.D.D.P.)of theDepartrnentof PrimaryIndusuryandEnergywentinto operationat Campbelltown DistrictHospitalnearSydney.The primarygoalof thispilot projectis to srudythe technicalfeasibilityof integratingsolarprocesssteamfrom an advanced"evacuated rube" typesolarcollectorsystem,with othercommercialsteemgenerators usinggasor electricity. The technicalandoperationalexpertisegainedfrom this pilot plant will bea vital stepto enableconstnrction of muchlargerdemonstration andcommercialplantsin thenearfuture(Mills et al., 1987). Sincetheinitid descriptionof the technicaldetailsof this project waspublishedin previousreports(Mills et al., 1987andHOSPLAN, 1987),somedesignchangeshave beenmadeandaredescribedin the following textwhereappropriate. SOI-ARCOLLECTORTECI{NOI-OGY Periodicallyadjustednon-trackingsolarcollectorsconsistingof linearparabolicthrough mirrorandevacuated rubeswith selectivesurfacecoatinghavebeenproposedasthemost cost-effective methodof harnessing (100-200oC) solarenergyin themediumtemperature range(Mills, 1986). Thecollectorusesevacuated tubularabsorbers and 1.4metrelong parabolictrough mirrorswith anapertueareaof 0.6m2each. Thesearefabricatedfrom galvanisediron sheetandlinedwith 0.3mmhightypolishedanodisedaluminiumfoil. F-ouneen such mirrorsareattached togetherasa singlemodulein a planararrangement of steelheat rransferpipes.Theevacuated collectortubes aresimplyslippedover the steelpipes,and canbeveryconveniently replacedif damaged Theefficiencyof themanufacnredcollector/mirrorassemblyhasbeenrecentlymeasured by a newandaccurate experimental methodusingmeasured amountsof waterboiledoff from anattachedhorplate,thelosscharacteristics of which areknown. As shownin Fig.1,efficiencywasfoundto becloseto 55Voat 15@Cfluid temperanreandthe collectorstagnated at 465oC.Opticaleffi.ciencyis estimatedat66Vo.The-collectors are not tracked,but areinsteadperiodicallytilt adjustedabouta dozentimesa year.
1A-11
SOLAR'88. ANZSESCONFERENCE MELBOURNENOVEMBER1988 SOI-ARGENERATINGSYSTEM Thearrayof solarcollectorswereinstalledon theslightlyinclined,metalcladroof of the m?tgnuryblockinslea4of on thelargerflat concreteroof of themainhospitalblock,as originallyproposed"Our analysisof thesteamloadshowedthattheauroclaves in the r.naternlty. wi-n-g offeredI largerandmoreconsistentload*ran rhedishwashingfaciliry on themain building..Twelvemodulesconsistingof fourteenmirron weredistributedalong theroof as shownin Fig.]. Installationwasrelatively straighdorwardand the array sufferedgnlyminorproblemson startup,predominantty dubto failuresor leakageiin cornmcrcialvalves. Thc arraywassplit into two halvesin a latedecisionduring-assembly in orderto improvemaintenanceaccess,andadditionalheaderexpansionjoints were requiredasa result On the fint day, slagfrom weldedsteelpipejoints wasbackwashed into thecondensate resenroirdueto a valvefailure,but this hasnot sinceoccurred Steel tubesbentduring constnrctionhavecausedsosreevacuatedtubebreakages,but theseare graduallybeingrectified by the hospitaistaff. The designhasrhebenefii that the rubes can bc replacedwithout array shutdown. In operation,chemicallytreatedwateris pumpedinto theheadertanksituatedon rheroof. The waterlevel of the headertankis maintainedat a consrantvalueby meansof a float controlledelectremcchanicalwaterflow rcgulaor. The wareris dire-ctlyfed into the pipeworkfrom below andthe steirnlis collecrcdat thehighcr headersid-e. Steamis deliveredthrougha non-returnvalve to main steamlinesin the basementof the bqtlding,after beingdtied with a steirmtrap. The main steamlines areconnectedto a pair of autoclavesusedQr gtcrilisingmedicalequipmenr The auroclaveswereoriginally drivenbytwo 80kW electricalboilersat all times. Now, duringsunnyweather,thd load is ca:riedby solarpoweredsteamwith the electricalboilerson stand-by.In caseof suddendrop of insolation(ie. cloud coveredsun)or a high loaddeman4 theelectric boilerstensea drop in stea4 pressurc,boostingup to requiredcapacirywirhin a short time. This sensingcapacityis completelyconventionalandis requiredin atl multi-boiler systems.This systcmhasno thermalstoragefacility andoperatesasa "fuel saver"with an expectedannualenergygainof approximately500GJfor Sydney(34oS).
cI]sTs Althougha technicaldemonstration, we aremonitoringenergyexpenditure saved.As the systemis on electricaldemandmriff, reductionin elecricalusagep"rLr areasimportant asenergyrcplacedbecause theyreducethecostof all elecaicirypurchased by rhehospital. Thesolarsystemproduceshighourputat thetimesof ma.ximum rraditionalload- near middayandin sunm€rwhenair-conditioningdemandis high. Reductionin electricalpeakdemandis worthabour$13perkilowartpermonthfor this 90!W systcm,but only about70kW will be usedto redubeelectricirypeakdemand.This yteld! anuP?erli-i! 9f +ogt $11,000p.a in demand-related savings.Conventionalgas andelectricitysavedlie in the rungeof $0.03-0.Mpcr kWh, or $0.01per MI, equivalent to an upperlimi3sf about$5,000p.a.savedin energyunit costsavings. Theestimatedinstalledcostof thearrayin largescaieproducrionwouldbe$3G36,000. The actu.alprojectpricefor theinstalledarraywasabout2.5 timesthatfigure,reflecting ye5Yhighlqbo* andrnaterialcostsattributableto our low producrionvolume. In spitJof this,a positivepaybackagainstelecricity seemsto beassured for this "hand-made'i sysrem.
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{'
SOLAR'88. AI.IZSESCONFERENCEMELBOURNENOVEMBER 1988 Againstgasheatingon thesite,if performance estimationsareverified, lifecyclecostsof aninstallationcosting$290per m2 wouldcompetewith gasat $0.01per MJ over a 15 yeararraylifetime, including 3Voawualmaintenance. Theauthorsareconfidentthata largescaledemonstration projectwould allow massproductiontechniques which*ollg yield considerably lower prices. The project engineeringcompanyestimatesfull productionex-factorymoduleprices ai $90-128per m?. LOAD CONSIDERATIONS A studyof the steamload duty cycle (Fig.3) showedthat the load wasessentiallyflat at about60kW with very shortterm bursa up to 160kW. Testsof the improvedc6Uectoron the Universityroof showedthat a reductionin arraysizefrom 194 squaremerresto 180 sqriaremetreswasdesirableandwould yield a peakpoweron sunnf daysabout90kW afterdeductionof l0Voltne losses.Allowing for lower input in the early rnorninp and lateafternoon,this shouldcompletelycov€rexpectedusagefor 6 hoursa dayon sunny dayq. The excesspowergenemtednearnoonwill be deliveredto a heatexchangerand usedfor heatingwaterandfor hospitalspaceheating. A systemoptimallydesignedto minimizepaybacktime could deliver a peakof 60kW and would allow the electricboilersto balarrcethe load at other times. However,this is a technicalprmf systemandwe areinterestedin acquiringinformation on interfacingwith different typesof fuels. The hot water systemis poweredby natural gas,and we have divertedexcesssteamto ttratsystem. Heu exchangngto thehot watersystemhasprovedexceptionallyeasyandcost-effective, with the35kW heatexchangerunit costing$1,550to insrall. Energyis deliveredto the hot watersystemwhenthepressurein the main steamline risesabovea presetfigure. Sucha risein pressurewill occur whenautoclaveload is insufficient to matchcoilector output. The shortdr:rationof high steamload periodssuggeststhat somebuffer storagewould be cost-effectivein furtherdepressingpeakelectricaldemand However, the arrayitself has somethermalcapacityandwe will studythis interaction. CHANGESDURING TI{E PROJECT Themirrorswereoriginallyto usechemicallypolishedstainlesssteel,thenaluminium laminate.However,duringthecourseof theprojecttherequired316 srainlesssteelrose very steeplyin priceandbecamevirnrally unavailabledue to hoardingabroad(Austraiian 316stainlesssteelhastoo poora surfacefinish). Althoughaccelerated indoortestshad shownno problern,corrosionwasdetectedin backuplong lifetime outdoortestsof the laminate,whichwasprotectedby a supposedly IJV stableTeflon "wax" product. As a result,we haveoptedfor an initial testperiodusingunprotectedanbdizedaluminium reflecton. Whenthis degrades, the liningswill bereplacedbya new sandwichof aluminiumandFEPteflon film usingno adhesiveor UV sensitivematerials. We estimate thelifetimeof theunprotected materialat l-3 years,andtheAI/FEP at anexcessof ten years.In principle,thealuminiumin thelaminatecanbe very thin. Corrosionof mi:rorsandpipeworkwill bemonitoredthroughoutthe liferimeof thearray by hospitalstaffandHOSPI-AN. This will yield valuablelong termdataunavailable elsewhere.
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SOLAR'88- ANZSESCONFERENCEMELBOURNENOVEMBER i988 The hospitalstafforiginaliybelievedantifreezemeasures to be unnecessary, but we found ice on the roof during installation,during a particularlycold pedd. An antifreezebackpumpingcontrolsensorhasbeeninstalledwhichwouldacruatewhenthecollectorpipe temp€rature droppedbelow4oC,whichhappensonly rarely. The costof modifrcarionis minimal,beingan alterationof the usualanti-scaleflushingcyclein conventionalboiler systems.The arrayis flushedin thesarneway, beinga parailetboiler to theothersin the system. INSTRI'MENTATION AND DATALOCGING The temperatures of inlet waterandoutgoingsteamaremonitoredat six different locations with K-type thermocouplesaswell asthe insolationwith a pyranometermountedon a mirror asshownin Fig.2. The ambientandthe temperatureof the headertank are also measured All themtocouplgleadsareconnectedto a 10channelsignalconditioningunit consistingof Analog Device'sAD-197 Temperatureto VoliageConverterChip and-the rqglting voltagesaresenttq qdat4logger(Manufacturer:DatatakerPty. Ltd.). ttre ourput of thepyranomet€rgivesa DC voltageproponionalto insolation(wat/squaremetre),tfius directly fed to the datalogger. The dataloggerat the Campbelltownsideis connectedwith a modemandcommunicates with the CommodoreAMIGA 500hostcomputerat the Schoolof Physics,Sydney Universityvia a telephoneline (Fig.4a).The simplifiedflow chartof thedata communicationsystemis shownin Fig.4b. MAINTENANCE The hospitalstaffhandleall routinemaintenance andsuggestsmall modificarionsfrom time to time. This is possiblesincethe arrayis, in essence,a conventionalboiler with a differentfuel. Much conventionalengineeringexpertiseis directly applicableto the runningof this system,andthis hasprovedaninestimableadvantage-during this project. While small problemsarisein all suchlargesystems,the staff in this one seemro be able to meetmostchallenges unaided.This is in directcontrastto largesolarinsrallacions overseas, whereindustrialdemonstrations oftenfailedafterthegfimt moneyran our for a want of expertise. SUMIVIARYAND COMMENTS The Campbelltown DistrictHospiul SolarSteamPilot Plantis successfullyoperaringand thepro_ject is on budget(exceptfor a newcatwalkrequiredbecauseof the changeofioof site). It is behindschedulein commissioningbecause of designandproductiondelays. Althoughcompletewithin theoriginalrwo yeargrantperiod,dataloggingis just resultswill besomewhatdelayedin presentation.Testof legt1ryngandperformance individualproductioncollectorsat theUniversityhaveexceeded expecrarions, however. Theoverallconceptappearsto be successful andpotentiallycost-effectiveasan industrial fuel. Mirror materialsaresdtl beingimproved,bur thescopefor cosrreductionin this otherlargesolarprojectsusingnew technology,srartup 3rea.isvery geat..Compared-to hasbeenremarkablytrouble-free.This isa resultof theexrremesimpliciryof the sysrem. Snrdiesarein progressfor a muchlarger,andmorecost-effectiveinstallationat Parkes cgngngeqton adequate funding,will providemostof *re energy fospiql. This projec,qtle hospital will and include 3-4 days energy storagein piessuisedhot water. Thls lor "totll ene-r-gy" *4 provide ul* electricalenergyat alater stageusinga steam -systeengineof local design, Backupenergywill be suppliedby LPG. We areawareof no othersuchprojectq tttp wg,rld,yet for townsandindustriesin Australiaandin sunny countriesoverseastheimplicationsof suchwork arevery exciting.
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SOLAR'88- ANZSESCONFERENCE MELBOURNENOVEMBER1988 This cost-effectiveAustralian solar technologyrepresentsa near-tennand potentially ex.tre-mely large scaleenergyresource. It is important now that energy plannersrecognise this fact.
REFERENCES i.
,, L.
a J "
Mills, D.R. and Moore, A., 'Cost Effective Solar Boiler'. ANZSES Conference. Canberra(1987) ppl23. HOSPLAN Internal Report, New South wales Hospitai Advisory Cenrre, Sydney (1987). 'Relative Mills, D.R. Cost-Effectivenessof Periodically Adjusted Solar Collectors Using EvacuatedAbsorber Tubes'. Solar Energy,36 No.4, pp323-33l, (1986)
FIGURES Figure 1 :
Efficiencyof thecollector/mirrorassembly with an averageinsolarionvalue of 916 wata/n0 measured by boilingoff of warerfrom an anached horplate.The experimentwascarriedout on a sunnycloudlessday.
Figure2 :
Schematic diagramof theiurangement of thesolarcollectormoduleson the roof of thematernityward of C.D.H. The thermocouples TC-1 andTC-8 measures thefeedwaterandambienttemperatures resirectively. Temperatures at differentlocationsof thearrayaredetectedby the therrnocoupies TC-2,TC-3,TC-4,TC-5,TC-6 andTC-7. The pyronometer PYR-I senses theinsolation.The safetyvalvesand joints arenot shownin thediagram. expansion
Figure3 :
steamloaddurycycleof theelectricalboilersysremof thec.D.H. artached to theautoclaves.
Figure4a :
Schematicdiagramof thedataioggingsysremof the C.D.H. solar-process steamplant.
Figure4b :
Simplifiedflow chartof thedatalogging procedure.
14-15
SOI-AR'88- AI.IZSESCONFERENCEMETBOURNE NOVEN{BER1988
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SOLAR'88 - ANZSESCONFERENCEMELBOURNENOVE}IBER 1988
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