闡述凝結(jié)水過冷度的定義和表示方法

闡述分散水過冷度的定義和表示方法2.1定義definitions分散水過冷度表征了凝汽器熱水井中分散水的過度冷卻程度,凝汽器熱水井出口分散水溫度與凝汽器在排汽壓力下對應(yīng)的飽和溫度之差即稱為過冷度。Characterization of condensate supercoolingdegreearetheovercoolingofthecondensateinthecondenserhotwell,thecondenserhotwellexportwatertemperatureandthecondenserintheexhauststeampressurecorrespondingtothesaturationtemperaturedifferencethatisreferredtoasthedegreeofsupercooling.表示方法2.2representationmethod溫度形式:Temperatureoftheform:δtn=ts-tcThedeltatn=ts-tc式中:δtn—分散水過冷度;“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxType:thedeltatn-condensatesupercoolingdegree;ts—Ts-condenserundertheabsolutepressureofsaturatedtemperature;tc—凝汽器熱井中分散水溫度。Tc-thecondensatetemperatureinthecondenserhotwell.3、過冷度產(chǎn)生的緣由3,thecauseofsupercoolingdegree凝汽器運行中產(chǎn)生分散水過冷卻現(xiàn)象可能是凝汽器設(shè)計中的問題,也可能是運行不當(dāng)而產(chǎn)生的,一般主要緣由有以下幾個。Producedintheoperationofthecondensercondensatesupercooledphenomenonmaybeaprobleminthedesignofthecondenser,alsomaybeimproperoperation,generallyhasthefollowingseveralmainreasons.“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjx3.1凝汽器內(nèi)管束排列不好withinthecondensertubebundlearrangementisnotgood在舊式構(gòu)造的凝汽器上,分散水過冷度可能很大。這些凝汽器通常均為非回?zé)崾降?凝汽器內(nèi)由于冷卻水管束布臵過密和排列不當(dāng),使汽氣混合物在通往凝汽器的管束中心和下部時存在很大的汽阻,引起凝汽器內(nèi)部確定壓力從凝汽器入口到抽氣口漸漸降低,使得凝汽器大局部區(qū)域的蒸汽實際分散溫度要低于凝汽器入口處的飽和溫度,形成了過冷度。這同時造成了蒸汽負荷大局部集中在上部冷卻管束處,蒸汽所分散的水通過密集的管束,又在冷卻水管外側(cè)形成一層水膜,又起到再冷卻分散水的作用,加之排汽不能回?zé)釤崴蟹稚⑺?進一步加劇了分散水的過冷卻。Intheoldstructureofthecondenser,thecondensatesupercoolingdegreecouldbelarge.Thecondenserisusuallyarenotregenerative,condenserinsideduetoimpropercoolingwatertubebundlearrangementtoocloseandarrangement,makethesteamgasmixtureinthecenterofthetubebundletothecondensersteamandlowerwhenthereisabigresistance,absolutepressureinsidea“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxcondenserfromcondenserinlettothepumpintakereducedgradually,makesmuchofthecondenserofsteamcondensationtemperatureislowerthanactualsaturationtemperatureattheentranceofthecondenser,formedthedegreeofsupercooling.Thiscausedasteamloadatthesametimemostlyin the upper cooling tube bundle, steamcondensationwaterthroughdensebundles,andformalayerofwaterfilmontheoutsideofthecoolingwaterpipe,alsohavetheeffectofcoolingthecondensateagain,combinedwiththeexhauststeamcan”tbacktohotWellsinthecondensate,furtherexacerbatingtheovercoolingofthecondensate.空氣漏入凝汽器或抽氣器工作不正常theairleakageintothecondenserorejectordoesn”tworkproperly缸、凝汽器以及低壓給水加熱系統(tǒng)等局部,假設(shè)有不嚴(yán)密不能準(zhǔn)時地把凝汽器內(nèi)漏入的空氣抽走。這兩方面使得凝汽器內(nèi)積存的空氣等不分散氣體增加,這不僅會在冷“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjx氣成分的增高,造成空氣分壓提高、蒸汽分壓降低,而分散水是在對應(yīng)蒸汽分壓的飽和溫度下冷凝,所以此時分散水溫度必定低于凝汽器壓力下的飽和溫度,因而產(chǎn)生了分散水的過冷卻。Unitoperationintheprocess,underavacuumofsteamturbineexhaustcylinder,condenserandlowpressurefeedwaterheatingsystem,iftherearenottight,itwillcauseairleakageintothe;Ejectorwork,ontheotherhand,isnotnormal,notinatimelymannertothecondenserleakintotheair.Accumulatedwithinthesetwoaspectsmakesthecondenseroftheairandcondensationgasincreases,thiswillnotonlyonthesurfaceofcoolingwaterpipeformbadairheattransferfilm,reducetheheattransfereffect,increasetheheattransferenddifference;Alsomakethesteamcondenserinthehighergasmixtureofaircomposition,increasecausedbyairpressure,steampartialpressureisreduced,andthecondensateisincorrespondingtothepartialpressureofsaturatedsteamcondensingtemperature,“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxsoatthispointthecondensatetemperaturemustbelowerthanthesaturationtemperatureofthecondenserpressure,thusproducedtheovercoolingofthecondensate.分散水水位過高thecondensatewaterlevelistoohigh運行過程中,由于分散水泵真空局部漏入空氣或其它故障,使凝汽器熱井中分散水水位過高,漂浮了下部使分散水再次被冷卻,過冷度必定增大。Operationprocess,becauseofthecondensatepumpvacuumpartleakintotheairorotherfault,thecondensateinthecondenserhotwellwaterlevelistoohigh,coveredthebottomofthecoolingwaterpipe,coolingwaterandtakeawaypartoftheheatofthefrozenwater,makewateriscooledagain,degreeofsupercoolingisboundtoincrease.冷卻水漏入分散水內(nèi)coolingwaterleakageintothewater分散水硬度增大的現(xiàn)象發(fā)生。“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxInsidethecondensercoolingwaterpipeburst,resultinginwaterleakageintothewater,lowerthewatertemperature,super-cooling degreeincrease,accompaniedbythephenomenonofwaterhardnessincreaseoccurredatthistime.凝汽器冷卻水入口溫度和流量的影響condensercoolingwaterinlettemperatureandflowrate現(xiàn)代電站凝汽器通常為回?zé)崾降?具有合理設(shè)計的管束構(gòu)造,汽阻微小,在額定的設(shè)計工況下運行時,分散水過冷度實際可為零。在這種狀況下,分散水過冷度主要受凝汽設(shè)備運行工況因素的影響,其中最重要的因素是凝汽器冷卻水的入口溫度和流量。Modernpowerplantcondenserforregenerative,usuallyhaveabundlestructureofreasonabledesign,steamresistancesmall,underthedesignconditionsofratedrunning,thecondensatesupercoolingdegreecanbezero.Inthiscase,thecondensatesupercoolingdegreeismainlyinfluencedbycondensingequipmentoperationconditionfactors,oneofthemostimportantfactoristhecondensercoolingwaterinlettemperature“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxandflowrate.試驗與運行閱歷說明,在肯定的蒸汽負荷下,當(dāng)冷卻水入口溫度降低或流量增加時,細石混凝土泵凝汽器壓力降低,真空增加,進入熱井的分散水的過冷度將增大。Testandoperationexperienceshowthatunderacertainloadofthesteam,whenthecoolingwaterinlettemperaturedecreaseorincreasetraffic,condenserpressure,vacuum,inhotwellofthecondensatesuper-coolingdegreewillincrease.蒸汽負荷的影響theinfluenceofsteamload凝汽器蒸汽負荷的大小對分散水過冷度也有肯定的影響。依據(jù)前蘇聯(lián)вти的試驗結(jié)果,對于汽流向心式凝汽器,隨著蒸汽負荷的提高,過冷度增大;而對于汽流向側(cè)式凝汽器,蒸汽負荷上升時,過冷度減小。對于舊起過冷度增加。Condensersteamloadonthesizeofthecondensatesuper-coolingdegreehasacertaininfluence.AccordingtotheformerSovietunionkindguideтиtestresults,forsteamflowtotheheart“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxtypecondenser,withtheimprovementofthesteamload,super-coolingdegreeincreased;Forthesteamflowtothelateraltypecondenser,steamloadincreases,thedegreeofsupercooling.Foroldnonregenerativecondenser,steamloadreduced,will inevitably cause super-cooling degreeincrease.將溫度較低的補充水直接補入凝汽器的熱水井Add3.7willbeaddedcoolerwaterdirectlyintothecondenserhotwell機組在運行過程中,由于鍋爐排污等緣由,導(dǎo)致工質(zhì)在循環(huán)過程中產(chǎn)生了汽水損失,因此為了滿足汽輪機補充水補入的位臵有除氧器和凝汽器兩種方案,假設(shè)承受況時凝汽器中分散水溫度可達十幾攝氏度。這樣將溫度較低的補充水直接補入凝汽器的熱水井,并且在補充水流量較大時,勢必會造成分散水溫度的降低,致使過冷度增加。Unitsintheprocessofoperation,duetoreasonssuchasboilerblowdown,causeworkingsubstance“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxproducedsodalossinthecirculationprocess,soinordertomeettheneedsofthesteamturbineinletsteamquantity,mustaddintothesodamediumcirculationsysteminatimelymanner.Supplementwateraddthelocationofthedeaeratorandcondensercoagulationtwoplans,ifaddcondenserdesign,make-upwaterinwintertemperatureislowerthanthedesignworkingconditionofthecondensateinthecondensertemperaturecanbeuptotendegreesCelsius.Suchlowtemperatureaddsupplementarywaterdirectlyintothecondenserhotwell,andtosupplementthewaterflowisbig,willcausethecondensatetemperatureisreduced,thesupercoolingdegreeincrease.4、過冷度對機組運行經(jīng)濟性和安全性的影響4,thesupercoolingdegreeofimpactontheeconomyandsafetyoftheequipmentoperation4.1對機組運行經(jīng)濟性的影響“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjximpactonunitoperationeconomicalefficiency凝汽器過冷度會增加冷源損失,引起作功力量的損失,降低系統(tǒng)的熱經(jīng)濟性。Condensersupercoolingdegreecanincreasethecoldsourceloss,causethelossofworkability,reducethethermalefficiencyofthesystem.n154.9/470,當(dāng)分散水過冷卻度增加2℃時,蒸汽等效焓降削減0.457kj/kg,機組效率相對降低0.051%,電廠標(biāo)準(zhǔn)煤耗0.198g/kw.h。假設(shè)該機組年運行小時數(shù)為7500h,那么,一臺該型號機組每年多耗標(biāo)煤為147.6t,相當(dāng)于每年多支出燃料本錢3.1萬元?？梢?分散水過冷度對因此實行各種措施降低分散水過冷度是格外必要和有意義的。A4.9/470typesteamturbineofn15calculationresultsshowthatwhenthecondensatesupercooleddegreeincrease2℃,thenewsteamtoreduce0.457kj/kgofequivalententhalpydrop,theunitefficiencyrelativelyreduced0.051%,thestandardcoalconsumptionofpowerplantby0.198g/kw.H.Assumethattheunitannualoperationhoursis7500“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxh,so,onethemodelunitsannuallymoreBiaoMeiconsumptionis147.6t,equivalenttomorethanayearspendingonfuelcosts31000yuan.Visible,thecondensatesupercoolingdegreehasdistincteffectontheeconomicoperationoftheunit,cannotbeignoredisanindicator,sototakevarious measures toreducethe condensatesupercooling degree isverynecessary andmeaningful.對機組運行安全性的影響4.2impactonunitoperationsafety分散水過冷度的存在會威逼機組運行的安全性和牢靠性。分散水溫度過低,即分散水水面上的蒸汽分壓含量增加,由于溶于分散水的氣體量和熱井水面上氣體的分壓力成正比。因此假設(shè)分散水消滅過冷度,則其含氧量增加,這將導(dǎo)致凝汽器內(nèi)換熱管、低加及相關(guān)管道閥門腐蝕加劇,以致降低設(shè)備的使用壽命,不利于機組的安全運行。這同時也加重了除氧器的工作負擔(dān),使除氧的給水管道和鍋爐省煤器管,引起泄漏和爆管。據(jù)統(tǒng)計,2023年某電廠凝汽器冷卻水管腐蝕造成的泄漏,使“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjx達5次?？梢?分散水過冷度的存在對機組運行安全性極為不利。Thecondensatesupercoolingdegreetherewillendangerthesafetyandreliabilityoftheequipment operation. Condensation watertemperaturewaslow,thepartialpressureofthesteamcondensatewater,gaspartialpressureincreases,madethegasdissolvedinthewatercontentincreases,becauseinthecondensategasamountandhotwellwatersurfaceisdirectlyproportionaltothepartialpressureofthegas.Soifappearscondensatesupercoolingdegree,theoxygencontentincreases,thiswillleadtothecondenserheatexchangetube,lowcorrosionintensifiesandrelatedpipelinevalve,soastoreducetheservicelifeofequipment,isnotconducivetothesaferunningoftheunit.Italsoaddstothedeaerator”sworkburden,makethedeaeratingeffectofdeaerator,seriouscorrosionathightemperaturewhentheyworkundertheenvironmentofwatersupplypipesandboiler“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxeconomizertubes,leakageanddetonationtube.Accordingtostatistics,in2023acertainpowerplantcondensercoolingwaterpipecorrosioncausedbytheleak,thewaterhardnessishigh,forcingthecrewcutoutputloadingleakfrequencyupto5times.Visible,theexistenceofcondensatesupercoolingdegreeofunitoperationtothedetrimentofsecurity.5、削減分散水過冷度的對策5,toreducethecondensatesupercoolingdegreeofcountermeasures通過上述對分散水過冷度產(chǎn)生緣由及其對機組運行經(jīng)濟性和安全性的影響的分析可以看到,分散水過冷度的存在威逼著機組運行的安全性和牢靠性,同時也會降低機組運行的經(jīng)濟性。因此須從設(shè)計、改造、檢修以及運行維護等各個環(huán)節(jié)對其實行有效措施,以期降低分散水過冷度,提高機組運行的經(jīng)濟性和安全性。Bytheabovereasonsofcondensatesupercooling“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxdegreeanditseffectontherunningefficiencyandsecurityanalysiscansee,thecondensatesupercoolingdegreeoftheexistenceofthethreattothesafetyandreliabilityoftheequipmentoperation,alsocanreducetherunningefficiency.Somustbefromthedesign,modification,maintenance,andoperationmaintenanceandsooneachlinktotakeeffectivemeasures,inordertoreducethecondensatesupercoolingdegree,improvetheeconomicbenefitofunitoperationandsafety.5.1設(shè)計中所實行的對策designcountermeasurestakenin在冷卻水管束設(shè)計中改進管束的布臵,在管束構(gòu)造中適當(dāng)留有足夠?qū)挼恼羝ǖ?這除了可以保證汽流均勻進入管束各區(qū)域外,還可保證局部排汽可直接通應(yīng)使抽氣口位臵離開分散水遠一些,以削減分散水過冷度;theimprovementinthedesignofcoolingwatertubebundletubebundlearrangement,properinthevascularbundleshaveenoughwidesteamchannel,inadditiontothiscanensureuniformsteamflow“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxintothetubebundledistrictoutside,stillcanensuresomeexhauststeamcanpassdirectlytothecondensingobjectsbottom,heatingwater,reducethecondensatesupercoolingdegree;Alsoshouldmakethebleedingpointlocationawayfromthecondensatefaraway,inordertoreducethecondensatesupercoolingdegree;從凝汽器入口至抽氣口的路徑應(yīng)力求直接,且有足夠的流通面積,蒸汽進入管束的流速不超過40m/s～50m/s,蒸汽沿程阻力盡量小,以削減汽阻,降低分散水的過冷度;fromthecondensertothepathoftheentrancetothesuctionportdirectly,andhaveenoughcirculationarea,theflowrateofthesteamintothetubebundleisnotmorethan40m/s~50m/s,steamon-wayresistancesmall,asfaraspossibletoreducethesteamresistance,reducethecondensatesupercoolingdegree;合理選擇凝汽器內(nèi)的淋水裝臵,優(yōu)化設(shè)計循環(huán)冷卻水量;selectionofcondenserinthewaterspraydevice,theoptimaldesignofcirculatingcooling“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxwater;汽輪機排汽口與凝汽器的連接承受柔性連接,theexhaustmouthconnectedtothecondenserofthesteamturbineadoptsflexibleconnection,inordertopreventconfusingcauseairleakageintotheoperationofinflation;對于排入凝汽器的各種疏水、補充水、再循環(huán)水水位,最好接至分散器上部蒸汽空間,并裝折流檔板,防止沖刷冷卻水管,以除掉這些水源中的空氣,削減對分散水溶氧及對過冷度的影響;forintothecondenserofhydrophobic,replenishwaterandcirculatingwaterandotheradditionalfluid,connecttothelocationofthecondensermustbehigherthanthatofthecondensatewaterlevel,thebestupperconnectedtothecondensersteamspace,andbaffleplate,“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxtopreventscourcoolingwaterpipe,inordertogetridofthewaterintheair,toreduceacrosscoldwaterdissolvedoxygenandthedegreeofinfluence;利用鍋爐連續(xù)排污對補充水進展加熱,以削減補入凝汽器的補充水對分散水的過冷卻。一般凝汽器的補充水箱與除氧器、連續(xù)排污擴容器布臵在同一平臺處,因此可在補充水箱內(nèi)加裝一組管式換熱器,由連續(xù)排污7675(6)usingtheboilercontinuoussewageformake-upwaterforheating,inordertoreducetheaddedwateraddcondenserovercoolingofthecondensate.Generaladditionaltankcondenseranddeaerator,continuousblowdownflashtankarrangedonthesameplatform,thuscansupplementthetankequippedwithasetofpipeheatexchanger,thecontinuousblowdownflashtankraisesthetube,thedomesticsewageasheatsource,heatexchangerintointurn(76)(on75)supplementedbyheatingthewater,andthenintothegutter.改造中所實行的對策“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxreformcountermeasurestakenin舊式凝汽器通常均為非回?zé)崾降?冷卻管束通道很窄,汽阻很大,可達1.3～2.0kpa,這本身就可使過冷度5℃～10是改造凝汽器冷卻管束構(gòu)造。如:Oldcondenserareusuallynonregenerative,coolingtubebundlechannelisverynarrow,steamresistanceisverybig,canreach1.3~2.0kpa,thatinitselfcanmakethesupercoolingdegreereach5℃to10℃.Fortheseoldcondenser,thecondensatesupercoolingdegreehaslittletodowithworkingcondition,eliminatethesupercoolingphenomenonistheonlyeffectivemeasurestotransformthecondensercoolingtubebundlestructure.Suchas:撤除一局部冷卻水管(削減一局部冷卻面積),讓排汽可深入到冷卻面中部,并留有足夠的寬度,但不穿通,使蒸汽能沿著冷卻面作均勻的安排,并使分散水加熱到排汽溫度;Part(1)thedemolitionofpartofthecoolingwaterpipe(reducecoolingarea),allowtheexhauststeam“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxintothecentralcoolingsurface,andhadenoughwidth,butnotthrough,canmakesteamalongthecoolingsurfaceoftheuniformdistribution,andmakesthewaterheatedtosteamdischargetemperature;inthecoolingbundlesreasonabledecoratesomecatchmentanddrainageelement;限制管束中汽流流速,使其盡可能不超過40m/s～50m/s。(3)bundleZhongQiflowvelocity,sothatitisnotasmuchaspossibleformorethan40m/s~50m/s.檢修中所實行的對策maintenancecountermeasurestakenin對真空系統(tǒng)進展灌水查漏,重點檢查凝汽器喉部、低壓抽汽管路、低壓缸軸封蒸汽進出管道焊口、低凝汽器水位計接頭處、疏水?dāng)U容器焊接處、與熱井連接的真空系統(tǒng)閥門等部位,并修補泄漏處;thevacuumsystemforwaterleak,checkthecondenserthroat,lowpressuresteamextraction“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxpipe,lowpressurecylinderinandoutofthepipejointandlowpressureshaftsealsteamcylinderflangejointsurface,thermalWells,condensatepipelineflangejointwelds,condenserwaterlevelgauge,jointdrainflashtankwelding,vacuumsystem,whichisconnectedwithhotwellvalveandotherparts,andrepairtheleak;檢查凝汽器內(nèi)的淋水裝臵;checkthetubeinthecondenserwaterdevice;對凝汽器水位調(diào)整器和軸封壓力調(diào)整器進展檢修;theregulatorandshaftsealwaterlevelinthecondenserpressureregulatorformaintenance;對抽真空系統(tǒng)進展檢修,保證抽氣設(shè)備的正常工作,以便運行時可準(zhǔn)時抽出凝汽器內(nèi)不分散氣體。(4)thevacuumsystemformaintenanceandrepair,thenormalworkoftheextractionequipment,sothattheruntimecantimelytakeoutinsidethecondensercondensategas.運行中所實行的對策intheoperationoftheadoptedcountermeasures保證真空局部的嚴(yán)密性“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjxensurevacuumrigor保證真空局部的嚴(yán)密性,防止空氣漏入,同時正確配臵抽氣器。這不僅是為了維持凝汽器內(nèi)的高真空度,也是防止分散水過冷的有效措施之一。投運行軸封壓力調(diào)整器,并將軸封壓力掌握在規(guī)定值內(nèi),以防止空氣從軸封漏入,影響凝汽器真空。Ensurepartvacuumrigor,preventleakageintotheair,atthesametimecorrectconfigurationofejector.Thisisnotonlytomaintainahighvacuumdegreewithinthecondenser,itisalsooneoftheeffective measures to prevent condensatesupercooling. Run forshaft sealpressureregulator,andshaftsealpressurecontrolwithinthespecifiedvalue,inordertopreventtheairfromtheshaftsealleakage,affectthecondenservacuum.對分散水水位及水質(zhì)的監(jiān)視與掌握ofcondensatewaterlevelandwaterqualitymonitoringandcontrol為了消退運行中分散水水位過高而造成的分散水過冷卻現(xiàn)象,一方面除了要求運行人員對分散水水位嚴(yán)格監(jiān)視外,另一方面可通過裝設(shè)分散水水位自動調(diào)整器“:///“://“://tastdmp/“://tastdmp“://taflmy/“://taflmy“://tastjx/“://tastjx可以利用分散水泵本身的運行特性,承受凝汽器低水位運行的方式。Inordertoeliminatethecondensateintheoperationofthecondensatesupercooledphenomenoncausedbywaterlevelistoohigh,ontheonehand,inadditiontotherequiredoperatingpersonneltothecondensatewateroutsidethestrictsupervision,ontheotherhandcanfurnishthecondensatewaterautomaticregulator