南师大锅炉原理课件13-3 汽水分离及蒸汽清洗装置

2025/6/22113.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置1.Steam-waterseparation汽水分离Subcriticalpressurerecirculatingboilersandsteamgenerators亚临界锅炉areequippedwithlargecylindricalvesselscalledsteamdrums.配备锅筒Theirprimaryobjectiveistopermitseparationofthesaturatedsteamfromthesteam-watermixtureleavingtheboilingheattransfersurfaces.实施汽水分离Thesteam-freewaterisrecirculatedwiththefeedwatertotheheatabsorbingsurfacesforfurthersteamgeneration.再汽化水冷壁等2025/6/22213.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置1)Functionofsteamdrum

锅筒的作用Thesaturatedsteamisdischargedthroughanumberofoutletnozzlesfordirectuseorfurtherheating.Thesteamdrumalsoservesto:mixthefeedwaterwiththesaturatedwaterremainingaftersteamseparation,给水混合mixthecorrosioncontrolandwatertreatmentchemicals(ifused),药剂混合purifythesteamtoremovecontaminantsandresidualmoisture,蒸汽清洗removepartofthewater(blowdown)tocontroltheboilerwaterchemistry(solidscontent),排污providelimitedwaterstoragetoaccommodaterapidchangesinboilerload.储水量以适应负荷快速变化2025/6/22313.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置Theprimaryfunctionofthesteamdrum主要功能

istopermittheeffectiveseparationofsteamandwater.Thismaybeaccomplishedbyprovidingalargesteam-watersurfacefornaturalgravity-drivenseparationorbyhavingsufficientspaceformechanicalseparationequipment.Highefficiencyseparationiscriticalinmostboilerapplicationsinorderto:preventwaterdropletcarryoverintothesuper-heaterwherethermaldamagemayoccur,防止水滴进入过热器minimizesteamcarryunderinthewaterleavingthedrumwhereresidualsteamcanreducetheeffectivehydraulicpumpinghead,减少蒸汽进入下降管preventcarryoverofsolidsdissolvedinthesteam-entrainedwaterdropletsintothesuperheaterandturbinewheredamagingdepositsmayform.防止溶解固体进入过热器2025/6/22413.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置Thelastitemisofparticularimportance.

Boilerwatermaycontaincontaminants污染物,principallyinsolution溶液.Thesearisefromimpuritiesinthemakeupwater,treatmentchemicalsandcondensatesystemleaks,aswellasfromthereactionofthewaterandcontaminantswiththeboilerandpreboilerequipmentmaterials.Evenlowlevelsofthesesolidsinthesteam(lessthan0.6ppm)candamagethesuperheaterandturbine.Becausethesolubilityofthesesolidsistypicallyseveralordersofmagnitudelessinsteamthaninwater,smallamountsofwaterdropletcarryover(greaterthan0.25%byweight)mayresultindramaticallyincreasedsolidscarryoverandunacceptabledepositioninthesuperheaterandturbine.Thedepositshavecausedturbinedamageaswellassuperheatertubetemperatureincreases,distortionandburnout.2025/6/22513.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置1.Steam-waterseparation汽水分离2)Fundamental锅筒内汽水分离的原理:Gravity-drivenseparation重力分离：利用蒸汽和水滴的密度差在空间自行分离.Inertia-drivenseparation惯性力分离：利用汽流方向改变时，蒸汽和水滴惯性力不同进行分离。Centrifugalforceseparation离心力分离：汽流旋转运动时，会产生离心力，水滴和蒸汽的密度不同，所以离心力也不同而进行的分离。Waterfilmseparation水膜分离：由于水和蒸汽的特性不同，水附着力大，易附于固体壁面形成水膜，从汽流中分离出.综合效果可以解决蒸汽带水，使蒸汽的湿度不大于0.05%。2025/6/22613.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置Across-sectionofahorizontalsteamdrumfoundonamodernhighcapacityfossilfuelboilerisshowninFig.19.Thisillustratesthegeneralarrangementof:baffleplates,挡板primarycycloneseparators,主旋风分离器Secondaryseparatorelements(scrubbers),二级分离洗涤器Waterdischarger排水Feedwaterinlets

给水进口2025/6/22713.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置baffleplates,挡板primarycycloneseparators,主旋风分离器secondaryseparatorelements(scrubbers),二级分离洗涤器waterdischarger排水feedwaterinlets给水进口Steamoutlet蒸汽出口2025/6/22813.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置Steam-waterseparationtakesplaceintwostages.Theprimaryseparation一次分离器removesnearlyallthesteamfromthewatersothatverylittlesteamisrecirculatedfromthebottomofthedrumthroughtheoutletconnection(downcomer)towardstheheatedtubes.Thesteamleavingtheprimaryseparatorsinhighpressureboilersstilltypicallycontainstoomuchliquidintheformofcontaminant-containingdropletsforsatisfactorysuperheaterandturbineperformance.Therefore,thesteamispassedthroughasecondarysetofseparators,orscrubberelements

二级分离组件(usuallycloselyspaced,corrugatedparallelplates波纹板)forfinalwaterdropletremoval.Thesteamisthenexhaustedthroughseveralconnections.2025/6/22913.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置3)Influencingfactorsonsteamseparation

影响因素Effectivesteamseparationfromthesteam-watermixturereliesoncertaindesignandoperatingfactors.Thedesignfactorsinclude:设计因素1.pressure,压力2.drumlengthanddiameter,锅筒长度和直径3.rateofsteamgeneration,产汽率4.averageinletsteamquality,蒸汽品质5.typeandarrangementofmechanicalseparators,6.feedwatersupplyandsteamdischargeequipmentarrangement,给水和蒸汽布置型式7.arrangementofdowncomerandriserconnectionstothesteamdrum.下降管和上升管布置2025/6/221013.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置3)Influencingfactorsonsteamseparation

影响因素Theoperatingfactorsinclude:操作因素1.pressure,压力2.boilerload(steamflow),锅炉负荷3.typeofsteamload,蒸汽形式4.chemicalanalysisofboilerwater,锅水化学分析5.waterlevel.锅水水位Primaryseparationequipmentgenerallytakesoneofthreeforms:三合一1.naturalgravity-drivenseparation,2.baffle-assistedseparation,and3.highcapacitymechanicalseparation.2025/6/221113.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置4)Naturalgravity-drivenseparation自然重力分离Whilesimpleinconcept,naturalsteam-waterseparationisquitecomplex.Itisstronglydependentuponinletvelocitiesandinletlocations,averageinletsteamquality,waterandsteamoutletlocations,anddisengagementofliquidandsteamabovethenominalwatersurface.SomeoftheseeffectsareillustratedinFigs.20and21.2025/6/221213.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置5)Baffle-assistedprimaryseparation挡板辅助Simplescreensandbafflearrangementsmaybeusedtogreatlyimprovethesteam-waterseparationprocess.ThreerelativelycommonbafflearrangementsareillustratedinFig.22.Ineachcase,thebafflesprovide:1)changesindirection,改变方向2)moreevendistributionofthesteam-watermixture,强化混合3)addedflowresistance,and增加阻力4)themaximumsteamflowtravellengthtoenhancethegravity-drivenseparationprocess.延长蒸汽流动路径Variouscombinationsofperforatedplates

多孔板

havealsobeenused.Theperformanceofthesedevicesmustbedeterminedbyexperimentalevaluationsandtheyaretypicallylimitedtosmaller,lowcapacityboilers.Pg.290图12-122025/6/22136)Mechanicalprimaryseparators

Centrifugalforceorradialaccelerationisusedalmostuniversallyformodernsteam-waterseparators.离心分离ThreetypesofseparatorsareshowninFig.23:theconicalcyclone,锥形旋风thecurvedarm曲线叶片thehorizontalcyclone.卧式旋风13.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置2025/6/22146)MechanicalprimaryseparatorsTheverticalcyclonesteamseparatorisshowninFig.24.

Thewaterformsalayeragainstthecylinderwallsandthesteammovestothecoreofthecylinderthenupward.Thewaterflowsdownwardinthecylinderandisdischargedthroughanannulusatthebottom,belowthedrumwaterlevel.Withthewaterreturningfromdrumstoragetothedowncomersvirtuallyfreeofsteambubbles,themaximumnetpumpingheadisavailableforproducingflowinthecircuits.Thesteammovingupwardfromthecylinderpassesthroughasmallprimarycorrugatedscrubber波纹板

atthetopofthecycloneforadditionalseparation.Undermanyoperatingconditions,nofurtherseparationisrequired.13.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置2025/6/221513.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置7)Otherseparatorscorrugatedscrubber2025/6/221613.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置汽水分离装置小结(高压锅炉)挡板：夹角不大于45º，1m/s旋风分离器(内置和外置)：4~6m/s波形板分离器：0.2m/s百叶窗分离器：厚度1~3mm，间距10mm多孔板(顶部、水下)：孔径6~10mm，6~8m/s钢丝网集气管粗分离细分离2025/6/221713.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置8)汽水混合物引入旋风分离的方式单位式总汇箱并联式分组汇箱并联式2025/6/22182.蒸汽清洗Steampurification1)Function目的降低蒸汽中的溶盐，减少选择性携带的盐份。2)Mechanism机理经分离后的蒸汽，再经过洁净水层(来自给水)进行清洗，使从浓度较大的炉水中出来的蒸汽在洁净的给水层中发生物质扩散，使溶于蒸汽中的盐份部分地转移到清洗水中。理论上可以提高蒸汽品质达40倍以上，但实际上，一般只能提高4~10倍。13.3Steam-waterseparationandsteampurification

第三节汽水分离及蒸汽清洗装置2025/6/22192.蒸汽清洗Steampurification:给水不能全部用来清洗蒸汽，原因在于：清洗中部分蒸汽凝结，水冷壁受热面要增加蒸汽凝结量的蒸发份额，分离器的负荷增加；蒸汽的凝结将给水温度