《过程控制技术》课件-调节阀的流量特性

Flowcharacteristicsofcontrolvalves调节阀的流量特性落版在此谢聪XieCong主讲教师Teacher调节阀的流量特性Flowcharacteristicsofcontrolvalves调节阀的流量特性Flowcharacteristicsofcontrolvalves关键部件Keycomponents调节阀的流量特性Flowcharacteristicsofcontrolvalves流量特性的理解和掌握，对于确保整个系统的稳定运行和高效控制，具有至关重要的意义。

Understandingandmasteringflowcharacteristicsareofcrucialimportanceforensuringthestableoperationandefficientcontroloftheentiresystem.Flowcharacteristicsofcontrolvalves调节阀的流量特性当你拧开浴室的淋浴喷头，为什么轻轻转动旋钮，水流会从涓涓细流突然变成喷涌的水柱？Whenyouturnontheshowerheadinthebathroom,whydoesagentleturnoftheknobsuddenlychangethewaterflowfromatrickletoagushingcolumn?调节阀就像“流体的指挥家”一样，精准控制着工业生产和日常生活中的介质流动。Controlvalvespreciselycontroltheflowofmediainindustrialproductionanddailylife,actinglike"conductorsoffluids".Flowcharacteristicsofcontrolvalves调节阀的流量特性当调节阀的阀芯移动时，流量是如何变化的？Whenthevalveplugofacontrolvalvemoves,howdoestheflowratechange?调节阀阀芯位移与流量之间的关系，对控制系统的控制品质有很大影响。Therelationshipbetweenthedisplacementofthecontrolvalveplugandtheflowratehasasignificantimpactonthecontrolqualityofthecontrolsystem.Definitionofcontrolvalveflowcharacteristics调节阀流量特性的定义Definitionofcontrolvalveflowcharacteristics调节阀流量特性的定义被控介质流过阀门的相对流量Q/Qmax与阀门的相对开度（相对位移）l/L之间的关系称为调节阀的流量特性。TherelationshipbetweentherelativeflowrateQ/Qmax

ofthecontrolledmediumflowingthroughthevalveandtherelativeopening(relativedisplacement)l/Lofthevalveiscalledtheflowcharacteristicsofthecontrolvalve.

Q/Qmax

——相对流量Q/Qmax

——Relativeflowratel/L——相对开度l/L——Relativeopening下面分二种情况进行讨论：Thiswillbediscussedintwocasesbelow：调节阀流量特性不仅与阀门结构和开度有关，还与阀前后的压差有关。Theflowcharacteristicsofacontrolvalveisnotonlyrelatedtothevalvestructureandopeningbutalsotothepressuredifferentialbeforeandafterthevalve.Definitionofcontrolvalveflowcharacteristics调节阀流量特性的定义Definitionofcontrolvalveflowcharacteristics调节阀流量特性的定义为了工程上分析方便Fortheconvenienceofengineeringanalysis先在阀前后压差固定情况下，确定调节阀的固有流量特性。First,determinetheinherentflowcharacteristicsofthecontrolvalvewhenthepressuredifferentialbeforeandafterthevalveisfixed;再延伸到阀前后压差变化的实际工况，确定调节阀工作流量特性。Extendittotheactualworkingconditionswherethepressuredifferentialbeforeandafterthevalvechangestodeterminetheworkingflowcharacteristicsofthecontrolvalve.调节阀固有（理想）流量特性Inherent(ideal)flowcharacteristicsofcontrolvalves常用流量特性Commonflowcharacteristics直线特性Linearcharacteristics等百分比特性Equalpercentagecharacteristics快开特性Quick-openingcharacteristics在将控制阀前后压差固定时得到的流量特性称为固有流量特性，它取决于阀芯的形状。Theflowcharacteristicsobtainedwhenthepressuredifferentialbeforeandafterthecontrolvalveisfixedis

calledtheinherentflowcharacteristics,whichdependsontheshapeofthevalveplug.Definitionofcontrolvalveflowcharacteristics调节阀流量特性的定义调节阀固有（理想）流量特性Inherent(ideal)flowcharacteristicsofcontrolvalves常用流量特性Commonflowcharacteristics直线特性Linearcharacteristics等百分比特性Equalpercentagecharacteristics快开特性Quick-openingcharacteristicsDefinitionofcontrolvalveflowcharacteristics调节阀流量特性的定义Classificationofcontrolvalveflow调节阀流量的分类Classificationofcontrolvalveflow调节阀流量的分类调节阀的相对流量Q/Qmax与相对开度l/L成直线关系，即单位位移变化所引起的流量变化是常数。TherelativeflowrateQ/Qmax

ofthecontrolvalveisinalinearrelationshipwiththerelativeopeningl/L.Thatis,thechangeinflowratecausedbyaunitdisplacementchangeisaconstant.用数学式表示为：Itcanbeexpressedmathematicallyas:

R——调节阀可调比R——rangeabilityofthecontrolvalve直线流量特性Linearflowcharacteristics可调比R为调节阀所能控制的最大流量与最小流量的比值TherangeabilityRistheratioofthemaximumflowratethatthecontrolvalvecancontroltotheminimumflowrate.

指阀门全关时的泄漏量Refertotheleakageratewhenthevalveisfullyclosed阀门按照流量特性能进行连续平稳控制的最小流量Theminimumflowrateatwhichthevalvecanperformcontinuousandstablecontrolaccordingtotheflowcharacteristics一般约为最大流量Qmax的2~4%，国产阀门的可调比一般为R=30。Itisgenerallyabout2-4%ofthemaximumflowrateQmax.TherangeabilityofdomesticvalvesisgenerallyR=30.直线流量特性LinearflowcharacteristicsClassificationofcontrolvalveflow调节阀流量的分类直线阀的流量放大系数在任何一点上都是相同的，但其对流量的控制力却是不同的。Theflowamplificationcoefficientofalinearvalveisthesameatanypoint,butitscontrolforceovertheflowrateisdifferent.控制力指阀门开度改变时，相对流量的改变比值（%）。Controlforcereferstotheratio(%)ofthechangeintherelativeflowratewhenthevalveopeningischanged.直线流量特性LinearflowcharacteristicsClassificationofcontrolvalveflow调节阀流量的分类Q/Q100L/LmaxS=1S=1开度10％时：Atanopeningof10％:开度50％时：Atanopeningof50%:开度80％时：Atanopeningof80%:[(20-10)/10]×100%=100%[(60-50)/50]×100%=20%[(90-80)/80]×100%=12.5%直线流量特性Linearflowcharacteristics以直线阀为例TakingalinearvalveasanexampleClassificationofcontrolvalveflow调节阀流量的分类Q/Q100L/LmaxS=1S=1开度10％时：Atanopeningof10％:开度50％时：Atanopeningof50%:开度80％时：Atanopeningof80%:较小的开度变化能引发流量大幅改变，控制灵敏度高。Asmallchangeinopeningcancausealargechangeinflowrate,withhighcontrolsensitivity.相同开度变化对流量的影响减弱，控制效果趋于平缓。Theinfluenceofthesameopeningchangeontheflowrateweakens,andthecontroleffecttendstobegentle.[(20-10)/10]×100%=100%[(60-50)/50]×100%=20%[(90-80)/80]×100%=12.5%直线流量特性Linearflowcharacteristics以直线阀为例TakingalinearvalveasanexampleClassificationofcontrolvalveflow调节阀流量的分类单位相对行程变化l/L所引起的相对流量变化Q/Qmax与此点的相对流量成正比关系。TherelativeflowratechangeQ/Qmax

causedbyaunitrelativestrokechangel/Lisproportionaltotherelativeflowrateatthispoint。等百分比（对数）流量特性Equalpercentage(logarithmic)flowcharacteristics

Classificationofcontrolvalveflow调节阀流量的分类曲线斜率（放大系数）随行程的增大而增大Theslopeofthecurve(amplificationcoefficient)increaseswiththeincreaseofthestroke.流量小时，流量变化小；Whentheflowrateissmall,theflowratechangeissmall;流量大时，流量变化大。Whentheflowrateislarge,theflowratechangeislarge.Classificationofcontrolvalveflow调节阀流量的分类等百分比（对数）流量特性Equalpercentage(logarithmic)flowcharacteristics等百分比流量特性的调节阀在小开度时，对流量的调节较为平缓，不会因为微小的开度变化就导致流量大幅波动，有利于在低流量区域进行精确、稳定的控制。Foracontrolvalvewithequalpercentageflowcharacteristics,whenitisatasmallopening,theadjustmentoftheflowrateisrelativelygentle,anditwillnotcauselargefluctuationsintheflowrateduetosmallopeningchanges,whichisconducivetopreciseandstablecontrolinthelowflowratearea.Classificationofcontrolvalveflow调节阀流量的分类等百分比（对数）流量特性Equalpercentage(logarithmic)flowcharacteristics例如：Forexample:在一些需要精细调节小流量的化工反应过程中，能避免流量突变影响反应进程。Insomechemicalreactionprocessesthatrequirefineadjustmentofsmallflowrates,itcanavoidsuddenchangesintheflowratefromaffectingthereactionprogress.在大开度时：随着开度增加，流量变化逐渐增大，能够快速响应并调节大流量，满足生产过程中对大流量快速调整的需求。Atalargeopening:Astheopeningincreases,thechangeintheflowrategraduallyincreases,enablingarapidresponseandadjustmentoflargeflowratestomeettheneedsforrapidadjustmentoflargeflowratesintheproductionprocess.Classificationofcontrolvalveflow调节阀流量的分类等百分比（对数）流量特性Equalpercentage(logarithmic)flowcharacteristics等百分比阀在各流量点的放大系数不同，但对流量的控制力却是相同的。Theamplificationcoefficientsofanequalpercentagevalveatdifferentflowratepointsaredifferent,butitscontrolforceovertheflowrateisthesame.Q/Q100L/LmaxS=1S=1开度10％时：Atanopeningof10％:开度50％时：Atanopeningof50%:开度80％时：Atanopeningof80%:分别增加10%开度，计算相对流量变化比值。Iftheopeningisincreasedby10%respectively,calculatetheratiooftherelativeflowratechange.Classificationofcontrolvalveflow调节阀流量的分类等百分比阀在各流量点的放大系数不同，但对流量的控制力却是相同的。Theamplificationcoefficientsofanequalpercentagevalveatdifferentflowratepointsaredifferent,butitscontrolforceovertheflowrateisthesame.Q/Q100L/LmaxS=1S=1开度10％时：Atanopeningof10％:开度50％时：Atanopeningof50%:开度80％时：Atanopeningof80%:（6.58%-4.68%）/4.68%≈41%（25.7%-18.2%）/18.2%≈41%（71.2%-50.6%）/50.6%≈41%Classificationofcontrolvalveflow调节阀流量的分类Q/Q100L/LmaxS=1S=1百分比阀在控制流量时，能够在不同的流量范围内都保持相对稳定的调节精度。Whencontrollingtheflowrate,apercentagevalvecanmaintainrelativelystableadjustmentaccuracyindifferentflowrateranges.对于负荷变化较大的控制系统具有很好的适应性，能够在小流量和大流量情况下都能实现较为精准的流量控制。Andhasgoodadaptabilitytocontrolsystemswithlargeloadchanges,achievingrelativelypreciseflowratecontrolinbothsmallandlargeflowratesituations.Classificationofcontrolvalveflow调节阀流量的分类开度较小时，随开度的增大，流量迅速增大，很快就达到最大，故称为快开特性。适用于迅速启闭的切断阀或双位控制系统。Whentheopeningissmall,astheopeningincreases,theflowrateincreasesrapidlyandsoonreachesthemaximum,soitiscalledthequick-openingcharacteristics.Itissuitableforshut-offvalvesortwo-positioncontrolsystemsthatrequirerapidopeningandclosing.Classificationofcontrolvalveflow调节阀流量的分类快开特性Quick-openingcharacteristics其它针对特殊需求的流量特性，如抛物线特性（图中蓝色虚线），介于直线和对数曲线之间，实际工程使用较少（只在特殊情况下使用）。Otherflowcharacteristicsforspecialneeds,suchastheparaboliccharacteristiccurve(thebluedotted