水利水电工程专业英语

范文范例学习指导SpecializedEnglishforGraduatesof2011Contents1HYDROPOWERPLANT................................................................................................................................11.1Hydropower........................................................................................................................................11.2AdvantagesofHydropower.........................................................................................................11.3DisadvantageofaHydroplant...................................................................................................21.4Multi-PurposeUses.........................................................................................................................2Irrigation..................................................................................................................................3Floodcontrol.........................................................................................................................3Navigation...............................................................................................................................3Recreation...............................................................................................................................3FishBreeding.........................................................................................................................41.5TypicalComponentsofaHydroelectricPlant.....................................................................4DamorBarrage....................................................................................................................4Water-ConduitSystem......................................................................................................4PowerHouse..........................................................................................................................5TailRace...................................................................................................................................5ElectricalPowerTransmission........................................................................................51.6ClassificationofHydroelectricPlants......................................................................................5Base-LoadandPeak-LoadPlants.................................................................................6Plantscanalsobeclassifiedasfollows:....................................................................6ClassificationontheBasisofAvailableHeads....................................................10word整理版范文范例学习指导2HYDRAULICTURBINES142.1Introduction142.1.1Sub-systemsofaWaterTurbine142.2ClassificationofWaterTurbines152.3PeltonTurbine162.3.1Injector172.3.2Runner172.3.3NumberofNozzles192.3.4Distributor202.3.5Casing202.3.6JetBrake222.3.7TailWaterDepressorSystem232.4FrancisTurbine232.4.1MainComponents242.4.2ScrollCase242.4.3StayVanesRing252.4.4GuideVanesMechanism262.4.5Runner272.4.6DraftTube292.4.7HeadCover302.4.8BottomRing312.4.9Shaft312.4.10TurbinePitLiner322.4.11DewateringofTurbine322.5PropellerandKaplanTurbine322.5.1Introduction322.5.2ImprovementinEfficiency332.5.3MainComponentsoftheRunner342.5.4LocationofServomotor362.5.5ScrollCase362.5.6AutomaticAirValves372.5.7ShaftoftheHydrounit372.5.8Over-speedProtectiveDevices372.6DeriazTurbine382.6.1Introduction382.6.2Servomotor403HVAC423.1Background42word整理版范文范例学习指导3.2Heating...............................................................................................................................................453.3Ventilation.........................................................................................................................................47Mechanicalorforcedventilation...............................................................................47Naturalventilation............................................................................................................48AirborneIllnesses..............................................................................................................493.4Airconditioning..............................................................................................................................493.5Energyefficiency............................................................................................................................52Heatingenergy..................................................................................................................52GeothermalHeatPump.................................................................................................53VentilationEnergyrecovery.........................................................................................53Airconditioningenergy.................................................................................................543.6AirFiltrationandCleaning........................................................................................................54CleanAirDeliveryRateandFilterPerformance.................................................543.7HVACindustryandstandards.................................................................................................55International........................................................................................................................55NorthAmerica(USA).......................................................................................................55Europe(UnitedKingdom).............................................................................................57Australia................................................................................................................................58Asia(India)...........................................................................................................................58word整理版范文范例学习指导1HYDROPOWERPLANT1.1HydropowerItisthepowergeneratedbyusingwaterastheenergy-supplyingagent.Inthiscase,waterisallowedtoflowfromahigherleveltoalowerlevelthroughaturbinewherethepotentialenergyofwaterisconvertedintokineticenergyandtheturbine,inturn,rotatesageneratortoproduceelectricity.Hydropowergenerationdependsupontheavailabilityofrainwater.Cloudsareformedbecauseoftheheatingofseawaterbythesun.Theymovetowardstheland,wherelow-pressurezonesareformedandastheygetcooled,moisturestartsprecipitating.Therainwaterstartsmovingtowardslowerlevelsbecauseofgravity,throughasystemofnaturaldrainsconsistingofnullahs,rivulets,riversandsoon.Thiswatercanbestoredinreservoirscreatedontherivers,byconstructionofdamsandcanbeusedtogeneratepower.Aftergeneration,thewaterisletoutintotheriverandgraduallytravelsfurtherandultimatelyreachesthesea.Hereitisheatedupbythesuntostartthenextcycle.Therefore,hydropowerisnothingbutconversionofsolarenergyintoelectricitythroughacircuitousroute.1.2AdvantagesofHydropowerHydropowergenerationisnon-wastingself-replenishingandnon-polluting.Itisaphysicalphenomenonandnochemicalchangeisinvolved.Watercomeoutunchangedfromtheturbineafterimpartingitsenergyandcanbeusedagaineitherforpowergenerationorforirrigation.Infact,thisisdoneinmulti-purposeriver-valleyschemesliketheChambalValleydevelopmentinIndiaandtheTennesseeValleydevelopmentinU.S.A.InthecaseoftheChambalValleydevelopment,powerisgeneratedwiththehelpofthesamewaterinthreepowerhouses,situatedoneafteranotherontheriver,beforebeingreleasedintoirrigationcanals.Asagainstthis,coal,oilornuclearfuelcanonlybeusedonce.word整理版范文范例学习指导Thesupplyofwaterisautomaticandthewaterutilizedinoneseasonisreplenishedbynatureinthenextseason.Thewaterreachesthepowerhousesiteonitsown-nominingoperationsandtransportationareinvolvedasinthecaseofcoaloroil.Waterpoweriscleanasitdoesnotproducecaseofthermalornuclearpowergenerationby-productsareemitted.anypollutants,whereasinthepollutionisinevitable,astoxicThehydropowerplantshaveveryhighefficiencies.Theturbineefficiencyisabove90percentandtheoverallefficiencycanbeabove80percentwhichismuchhigherthanthatofthermalplants.Thehydro-plantsarelonglastingandmanyplantsarestillinserviceeven40yearsaftercommissioning.Thepercentageofoutagesisverylow,asshutdownsforrepairsandmaintenancearefewer.Theplantsareavailableforinstantloadingandasetcanstarttakingfullloadwithinfiveminutes,startingfromthestandstillposition,whereasthermalplantsmaytakeaboutfivetosixhours.1.3DisadvantageofaHydroplantTheinitialinvestmentsareveryheavyandthespecificcostishighcomparedtoathermalplant.Thetimeneededforconstructionisquitelonganditaffectstheeconomyadverselyasreturnsstartflowinginlate.Whenalakeisformed,landsubmergencecreatesitsownproblem.Astheavailabilityofwatervariesfromyeartoyear,inlowrainfallyearstheplantcapacityisunder-utilized.Anywaytheadvantagesfaroutweighthedisadvantages.1.4Multi-PurposeUsesAsalreadystartedearlier,anumberofadditionalbenefitscanbeobtainedfromwaterstoredbesidesgeneratingpower,suchasirrigation,floodcontrol,navigationandsoon.Themulti-purposeuseofwatergivesmuchbetterword整理版范文范例学习指导returnsoninvestmentandthereismarkedimprovementinthecost-benefitratio.1.4.1IrrigationThewaterbeingdischargedfromapowerhousecanbefedintoacanalnetworktoprovideirrigationfacilitiestolandsituateddownstream.Asamatteroffact,inmanymulti-purposeprojectsinIndia,waterisstoredpredominantlyforirrigationpurposeswithpowergenerationplayingasecondaryrole.1.4.2FloodcontrolCreationoflakeonariverhastheinherentpossibilitiesoffloodmoderation.Thefloodwatersmaybefullyorpartlyabsorbedinthelakeandonlyregulatedquantitiesofwaterareallowedtopassdownstream,protectingthelowerareasfromfloods.Thisaspectassumesgreatimportanceinthecaseofrivers,whichgoondevastatinglargetractsoffertilelandandvaluablepropertyyearafteryear.1.4.3NavigationTheformationofstoragereservoirincreasesthenormalwaterlevelinariver.Manypoolsandshallowstretchesoftherivergetsubmergedunderwaterandasufficientdepthofwaterbecomesavailableforshiptonavigatethesestretches.Thusfacilitateseconomictransportofcargoandpassengers.Themulti-purposedevelopmentoftheriverDanubeinEuropeisatypicalexampleofcombiningnavigationwithpowergeneration.It’slinkingupwiththeriverRhinehasallowedtheshipstopassfromtheNorthSeatotheBlackSea.Barrageshavebeenconstructedatanumberofpointsintheriverincreasingtheupstreamwaterlevelsandpowerisbeinggeneratedattheseplaces.Theonlyadditionalconstructionneededistoprovidenavigationallocksatthesitesofthebarragefortheuninterruptedmovementofaship.1.4.4RecreationCreationareservoirofwaterconsiderablyenhancesthebeautyandcharmofword整理版范文范例学习指导surroundingareasandtouristresortsandpicnicspotsarebeingdevelopedintheseareas.1.4.5FishBreedingItcantakeplaceonalargescaleandfishcanbemadeavailableeconomicallytothepopulationlivingintheneighboringareas.1.5TypicalComponentsofaHydroelectricPlantThemaincomponentsare(Fig.1.1):(i)Thedam,(ii)Thewater-conduitsystem,Thepowerhouse,(iv)Thetail-watersystem,(v)Theswitchyard,and(vi)Thetransmissionlines.1.5.1DamorBarrageAdamorabarrageisconstructedontherivercourseresultinginanincreaseintheupstreamwaterlevelbecauseoftheformationofareservoirwhosestoragecapacityisdecidedbythewaterrequirementforpowergeneration.1.5.2Water-ConduitSystemWater-conduitsystemcarrieswaterfromthereservoirtothepowerstation.Itmayconsistofapressuretunneland/orpipescalledpenstockswhichmaybelaidabovegroundorunderground.Onepenstockmayfeedanumberofturbines,whereanumberofbrancheshavetotakeoff.Flow-controlvalvesmaybeprovidedbeforewaterisadmittedtotheturbines.Asurgetankisoccasionallyprovidedtorestricttheeffectsofwaterhammer.word整理版范文范例学习指导Fig.1.1Typicallayoutofahighheadhydroelectricplant1.5.3PowerHouseThepowerhouseaccommodatestheturbinesandgenerators,thecontrolequipmentandinsomecasesthetransformers.Itslocationcanbeeitheratthesurfaceorundergroundanditmaybeawayfrom,atthefootof,orinthebodyof,thedam.1.5.4TailRaceThewater,afterpassingthroughtheturbine,isdischargedintothetailracewhich,inturn,carriesittoariver.Thetailracecanbeanopenchannelasinthecaseofasurfacepowerhouse,oratunnelasinthecaseofanundergroundpowerhouse.Thedischargefromalltheturbinesiscollectedinthetailraceatitsbeginningbymeansofbranchchannels.Thetailracemaydischargeintotheoriginalriveritselfor,inrarecases,someotherriverwhenthereisaninter-basintransferofwater.1.5.5ElectricalPowerTransmissionTheelectricalpowergeneratedbythegeneratorsisfedtothestep-uptransformersbymeansofcablesasthegeneratingvoltagemaybemuchlessthanthetransmissionvoltage.Thepoweristhensuppliedtothetransmissionnetworkviaaswitchyardwheretheswitchingandprotectiveequipmentisinstalled.Theswitchyardislocatedwithinashortdistanceofthepowerhouse.Transmissionlinestakeoffindifferentdirectionstosupplypowertotheconsumers.Inthecaseofcombinedhydropowerandirrigationmulti-purposeprojects,acanalnetworkisestablisheddownstreamofdam.1.6ClassificationofHydroelectricPlantsTheycanbeclassifiedonthebasisoftheoperatingheads,theoutputorsomeotherimportantfeatures,suchasthenatureofduty.word整理版范文范例学习指导1.6.1Base-LoadandPeak-LoadPlantsEveryhydro-plantisanindividualentityandnotwoplantsareidenticalasregardsthehead,availabilityofpowerandsoon.Ahydro-plantworksasabase-loadplantifthereiscontinuouspowergeneration.Thisisespeciallythecaseiftheflowthroughtheriverhastobemaintainedconstantformeetingtheirrigationornavigationrequirements.Iftheconditionsprevailingatthepowerstationpermitregulatedreleases,theplantcanbeusedtogeneratepeakpower.Forexample,theRoselandplant(France)isdesignedtomeetthepeakwinterdemandfromwaterlargelystoredduringthesummerperiod.1.6.2Plantscanalsobeclassifiedasfollows:Conventionalhydro-plantswithvalleystorage.Run-of-the-riverplants.Diversiontypeofplants.Pumpedstorageplants.Tidal-powerplants.ValleystorageplantsInthecaseofconventionalhydro-plants,areservoirhastobecreatedontherivertostoresufficientrainwater,forpowergenerationthroughouttheyearbyconstructionofadam.Thesetypesofplantsaresub-dividedintohigh-headplants,medium-headplants,andlow-headplants(Fig.1.2).Itisdifficulttolaydownexactranges.However,thefollowinglimitsarerecommended(theyarearbitraryandareasgoodasanyotherarbitraryrangesrecommended):High-headplants-havingheadsofmorethan250m.Medium-headplants-havingheadsbetween50mand250m.word整理版范文范例学习指导(iii)Low-headplants-havingheadslessthan50m.Fig.1.2TheGeheyanvalleystorageplant(China)Today,theplantcapacitiesrangefromafewhundredkilowattstothousandsofmegawattswithindividualunitcapacitiesrangingfromfewhundredkWto700,000kWanditisratherdifficulttoclassifytheplantsoncapacitybasis.Run-of-the-riverplantsFig.1.3ChiefJosephDamnearBridgeport,Washington,USA,isamajorrun-of-the-riverstationwithoutasizeablereservoirword整理版范文范例学习指导Theseplantsgeneratepoweronriverswithacontinuousflowthroughouttheyearwithminorseasonalvariations.Suchconditionsprevailmainlyincoldercountriesbutrarelyintropicalregions.Thestorageneededisminorandcanbecreatedbybuildingabarrageacrosstheriver,whichraisesthewaterlevelcreatingsomeheadforpowergeneration.Thesitechosenshouldbeonastablereachoftheriverwithstablebedandbanks.Themaximumfloodanticipatedshouldhavealowvalueandwatershouldnotcarrymuchsediment.Creatingasmallpooldoesnotcreateproblemsoflandacquisitionanddoesnotsubstantiallyaltertheoriginaltopographyalongthebanksoftheriverassubmergenceislow.Thispoolmayalsobeusefulfornavigation(Fig.1.3).SuchplantsarequitepopularinEurope.AchainofsuchplantshavebeenconstructedontheDanubetofullyutilizeitspowerandnavigationpotential.DiversionCanalPlantsThesediversiontypeofplantscangeneratepower,takingadvantageoftheleveldifferenceonacurvedmeanderingstretchofariverwithasteepbed-slope.Adiversioncanalwithaflatslopeinwhichtheflowfromtheriverisdivertedtakesofffromthehigherreachesofthemainriver.Aweirisconstructedattheendofthecanaltocreateasmallpoolofwater,calledtheforebay.Thewaterfromtheforebayisfedbymeansofthepenstockstothepowerhousesituatedinthelowreachoftheriver(Fig.1.4).word整理版范文范例学习指导Fig.1.4DiversionhydropowerplantPumpedStoragePlantsApumped-storageplantusestworeservoirs,onelocatedatamuchhigherelevationthantheother.Duringperiodsoflowdemandforelectricity,suchasnightsandweekends,energyisstoredbyreversingtheturbinesandpumpingwaterfromthelowertotheupperreservoir.Thestoredwatercanlaterbereleasedtoturntheturbinesandgenerateelectricityasitflowsbackintothelowerreservoir.Thesearepeakloadplantswhereduringoffpeakperiodstogenerateperiod.waterispumpeduptoahigherlevelpeakpowerduringthehighdemandword整理版范文范例学习指导Fig.1.5PumpedstorageplantTidalPowerPlantsThesedependontidesforgeneratingpower.Thissourceisunconventionalandalotofimportanceisbeinggiventothistypeofplant.1.6.3ClassificationontheBasisofAvailableHeadsTherearevariousclassificationsofhydroelectricpowerplants.Basedonthetotalheadofwateravailablethehydroelectricpowerplantsareclassifiedintothreetypes:lowheadhydroelectricpowerplants,mediumheadhydroelectricpowerplants,andhighheadhydroelectrcipowerplants.1.6.3.1LowheadhydroelectricpowerplantsFig.1.6Cross-sectionofatypicallowheadplantThelowheadhydroelectricpowerplantsaretheonesinwhichtheavailableword整理版范文范例学习指导waterheadislessthan30meters.Thedaminthistypeofpowerplantsisofverysmallheadmaybeevenoffewmetersonly.Incertaincasesweirisusedandinothercasesthereisnodamatallandmerelyflowingwaterintheriverisusedforgenerationofelectricity.Thelowheadtypesofhydroelectricpowerplantscannotstorewaterandelectricityisproducedonlywhensufficientflowofwaterisavailableintheriver.Thustheyproduceelectricityonlyduringparticularseasonswhenabundantflowofwaterisavailable.Sincetheheadofwaterisverysmallinthesehydroelectricpowerplants,theyhavelesserpowerproducingcapacity.InsuchplantsFrancis,PropellerorKaplantypesofturbinesareused.Alsonosurgetankisrequired.1.6.3.2MediumheadhydroelectricpowerplantsThehydroelectricpowerplantsinwhichtheworkingheadofwaterismorethan30metersbutlessthan300metersarecalledmediumheadhydroelectricpowerplants.Thesehydroelectricpowerplantareusuallylocatedinthemountainousregionswheretheriversflowsathighheights,thusobtainingthehighheadofthewaterindambecomespossible.Inmediumheadhydroelectricplantsdamsareconstructedbehindwhichtherecanbelargereservoirofwater.Waterfromthereservoircanbetakentothepowergenerationsystemwhereelectricityisgenerated.TheturbinesusedareFrancistypeofthesteelencasedvariety.Fig.1.7Cross-sectionofatypicalmediumheadplant1.6.3.3HighheadhydroelectricpowerplantsInthehighheadhydroelectricpowerplantstheheadofwateravailableforword整理版范文范例学习指导producingelectricityismorethan300metersanditcanextendevenupto1000meters.Thesearethemostcommonlyconstructedhydroelectricpowerplants.Inthehighheadhydroelectricpowerplantshugedamsareconstructedacrosstherivers.Thereislargereservoirofwaterinthedamsthatcanstorewateratveryhighheads.Waterismainlystoredduringtherainyseasonsanditcanbeusedthroughouttheyear.Thusthehighheadhydroelectricpowerplantscangenerateelectricitythroughouttheyear.Thehighheadhydroelectricpowerplantsareveryimportantinthenationalgridbecausetheycanbeadjustedeasilytoproducethepoweraspertherequiredloads.Whenconstructingthehighheadtypesofhydroelectricpowerplantsanumberoffactorsespeciallythoserelatedtotheenvironmentandnaturalecosystemofthelandandwatershouldbeconsidered.Thetotalheightofthedamdependsuponanumberoffactorslikequantityofavailablewater,powertobegenerated,surroundingareas,naturalecosystemetc.Mainlyintheseplantspressuretunnelisprovidedbeforethesurgetank,whichinturnconnectedtopenstock.Apressuretunnelistakenofffromthereservoirandwaterbroughttothevalvehouse(notshowninpicture)atthestartofthepenstocks.Thepenstocksarehugesteelpipeswhichtakelargequantityofwaterfromthevalvehousetothepowerhouse.Thevalvehousecontainsmainsluicegatesandinadditionautomaticisolatingvalveswhichcomeintooperationwhenthepenstockbursts,cuttingfurthersupplyofwater.Surgetankisanopentankandisbuiltjustinbetweenthebeginningofthepenstocksandthevalvehouse.Inabsenceofsurgetank,thewaterhammercandamagethefixedgates.Normallythehighheadplantsare500metersaboveandforheadsabove500metersPeltonwheelsareused.word整理版范文范例学习指导Fig.1.8Cross-sectionofatypicalhigh