《水处理技术（双语）》课件-转子流量计

Rotorflowmeters转子流量计转子流量计的特点Featuresofrotorflowmeters转子流量计又称浮子流量计，浮子流量计作为直观流动指示或测量精确度要求不高的现场指示仪表，它可测量液体、气体和蒸汽的流量，被广泛地用在电力、石化、化工、冶金、医药等流程工业和污水处理等方面。Rotorflowmeter,alsoknownasfloatflowmeter,floatflowmeterasanintuitiveflowindicationormeasurementaccuracyrequirementsarenothighfieldindicationinstrument,itcanmeasuretheflowofliquid,gasandsteam,iswidelyusedinelectricpower,petrochemical,chemical,metallurgical,pharmaceuticalandotherprocessindustriesandsewagetreatment.其特点有：Itscharacteristicsare:转子流量计的特点Featuresofrotorflowmeters压力损失小且恒定smallandconstantpressurelosses测量范围比较宽

arelativelywidemeasuringrange.量程比1:10arangeratioof1:10.工作可靠且刻度线性，reliableoperationandlinearscale.使用维修方便，对仪表前后直管段长度要求不高；easytouseandmaintain,withlowrequirementsforthelengthofthestraightpipesection

beforeandaftertheinstrument.

但受被测液体的密度、黏度、纯净度以及温度、压力的影响，也受安装垂直度的影响，其测量精确度为±2％左右。However,itisaffectedbythedensity,viscosityandpurityoftheliquidbeingmeasuredaswellasthetemperatureandpressure,andalsobytheverticalityoftheinstallation,anditsmeasurementaccuracyisaround±2%.转子流量计工作原理Rotorflowmeterworkingprinciple

浮子流量计的流量检测元件是由一根自下向上扩大的垂直锥形管和一个沿着锥管轴上下移动的浮子组所组成。工作原理如图所示。Theflowdetectionelementofafloatflowmeterconsistsofaverticalconicaltubethatexpandsfromthebottomupwardsandasetoffloatsthatmoveupanddownalongtheaxisoftheconicaltube.Theoperatingprincipleisshowninthediagram.被测流体从下向上经过锥管1和浮子2形成的环隙3时，浮子上下端产生差压形成浮子上升的力，当浮子所受上升力大于浸在流体中浮子重量时，浮子便上升，环隙面积随之增大，环隙处流体流速立即下降，浮子上下端差压降低，作用于浮子的上升力亦随着减少，直到上升力等于浸在流体中浮子重量时，浮子便稳定在某一高度。Themeasuredfluidfromthebottomupthroughtheconetube1andfloat2toformtheringgap3,thefloatupperandlowerendofthedifferentialpressuretoformthefloatrisingforce,whenthefloatbytherisingforceisgreaterthantheweightofthefloatimmersedinfluid,thefloatwillrise,theareaoftheringgapthenincreases,thefluidflowrateattheringgapimmediatelydrop,thefloatupperandlowerendofthedifferentialpressuredecreases,therisingforceonthefloatalsodecreases,untiltherisingforceisequaltothefloatimmersedinfluidWhentheweightofthefloatisimmersedinthefluid,thefloatwillbestabilizedatacertainheight.浮子在锥管中高度和通过的流量有对应关系。Thereisacorrespondencebetweentheheightofthefloatinthe

taperedtubeandtheflowratethroughit转子流量计工作原理Rotorflowmeterworkingprinciple转子流量计工作原理Rotorflowmeterworkingprinciple体积流量

的基本方程式为：Thebasicequationforvolumetricflow

isWhenthefloatisanon-solidcorehollowstructure,thebasicequationis转子流量计工作原理Rotorflowmeterworkingprinciple式中α－仪表的流量系数，因浮子形状而异；whereα-theflowcoefficientoftheinstrument,whichvariesaccordingtotheshapeofthefloat.

ΔF-流通环形面积m2;

ΔF-circulationringarea,m².g-重力加速度，m/82;

g-accelerationofgravity,m/s2.Vf-浮子体积，如有延伸体亦应包括，m3;

Vf--floatvolume,includingextensionsifany,m3.Pf-浮子材料密度，kg/m3;

Pf-densityoffloatmaterial,kg/m3.

P-被测流体密度，如为气体是在浮子上游横截面上的密度，kg/m3。

P-densityofthefluidbeingmeasured,inthecaseofagasisthedensityinthecross-sectionupstreamofthefloat,kg/m3;Ff-一浮子工作直径(最大直径)处的横截面积，㎡

Ff-cross-sectionalareaattheworkingdiameterofthefloat(maximumdiameter),m².Gf-一浮子质量，kg

Gf-floatmass,kg.转子流量计工作原理Rotorflowmeterworkingprinciple流通环形面积与浮子高度之间的关系如式（3-3）所示，当结构设计已定，则d、β为常量。Therelationshipbetweentheflow-throughannulusareaandthefloatheightisshowninequation(3-3).Whenthestructuraldesignhasbeendetermined,thendandβareconstants.式中有h的二次项，一般不能忽略此非线性关系，只有在圆锥角很小时，才可视为近似线性。Thereisaquadratictermofhintheequation,andthisnon-linearrelationshipcannotgenerallybeignored,andcanonlybeconsideredapproximatelylinearwhentheconeangleisverysmall.转子流量计工作原理Rotorflowmeterworkingprinciple式中d---浮子最大直径（即工作直径），m；

whered-themaximumdiameterofthefloat(i.e.theworkingdiameter),m.h--浮子从锥管内径等于浮子最大直径处上升高度，m；h-heightofriseofthefloatfromtheinnerdiameteroftheconetubeequaltothemaximumdiameterofthefloat,m.

β－锥管的圆锥角；β-coneangleoftheconetube.a，b-常数a,b-constants透明锥形管浮子流量计如图所示。Thetransparentconicaltubefloatflowmeterisshowninthediagram.透明锥形管用得最普遍的由硼硅玻璃制成，习惯简称玻璃管转子流量计。Themostcommonlyusedtransparentconicaltubeismadeofborosilicateglassandiscustomarilyreferredtoasaglasstuberotameter.流量分度直接刻在锥管外壁上，也有在锥管旁另装分度标尺。Theflowisgradeddirectlyontheouterwalloftheconicaltube,butthereisalsoaseparategraduationscaleinstallednexttotheconicaltube.（1）玻璃管转子流量计Glasstuberotameter转子流量计的特点Featuresofrotorflowmeters转子流量计的特点Featuresofrotorflowmeters321较大口平滑面内壁仪表采用导杆导向。Largermouthswithsmoothinnerwallgaugesareguidedbyguiderods.锥管内腔有圆锥体平滑面和带导向棱筋（或平面）两种。Theinnerchamberoftheconicaltubehasasmoothconesurfaceandaguiderib(orflat)oftwokinds.浮子在锥管内自由移动，或在锥管棱筋导向下移动，Thefloatisfreetomovewithintheconetube,orintheconetuberibbedguidetomove.转子流量计的类型Typesofrotorflowmeters（2）金属管转子流量计Metaltuberotorflowmeter金属管转子流量计与玻璃转子流量计具有相同的测量原理Metaltuberotameterandglassrotameterhavethesamemeasuringprinciple不同的是其锥管由金属制成，这样不仅耐高温、高压，而且能选择适当的材质以适合各种腐蚀性介质的流量。Thedifferenceisthatitsconicaltubeismadeofmetal,sothatitisnotonlyresistanttohightemperatureandpressure,butalsoabletochoosetheappropriatematerialtosuittheflowofvariouscorrosivemedia.转子流量计的类型Typesofrotorflowmeters浮子的位移量与流量的大小成比例，通过磁耦合系统，以不同接触方式，将浮子位移量传给指示器指示出流量的大小，并通过转换器，将流量值转换成标准的电远传信号，从而实现远距离显示、记录、积算和控制功能。Thedisplacementofthefloatisproportionaltothesizeoftheflow.Throughthemagneticcouplingsystem,thefloatdisplacementistransmittedtotheindicatorindifferentcontactwaystoindicatethesizeoftheflow,andthroughtheconverter,theflowvalueisconvertedintoastandardelectricalremotesignal,thusachievingremotedisplay,recording,accumulationandcontrolfunctions.流量计主要由传感器（测量管及浮子）和信号变送器（指示器）两大基本部分组成：Theflowmeterconsistsoftwobasicparts:thesensor(measuringtubeandfloat)andthesignaltransmitter(indicator).金属管转子流量计在指示器的设计上可以为各种应用场合提供可靠适用的功能组合，如现场指针显示、LCD显示瞬时和累计流量等。在指示器供电选择方面有电池供电、24VDC供电、220VAC供电，方式根据现场情况选择。金属转子流量计如图所示。Metaltuberotameterintheindicatordesigncanbeforavarietyofapplicationstoprovideareliableandsuitablecombinationoffunctions,suchasfieldpointerdisplay,LCDdisplayinstantaneousandcumulativeflow,etc..Intheindicatorpowersupplyoptionsarebatterypowered,24VDCpowered,220VACpowered,thewayaccordingtositeconditionstochoose.Themetalrotameterisshowninthediagram.转子流量计的类型Typesofrotorflowmeters

转子流量计是污水处理厂最常用的一种流量计Rotameteristhemostcommonlyusedtypeofflowmeterinwastewatertreatmentplants通过刻有流量标度尺的锥形玻璃管和管内浮子的位置高度，直接观察管道内流体流量。Thefluidflowinthepipeisdirectlyobservedbymeansofaconicalglasstubeengravedwithaflowscaleandtheheightofthefloatpositioninthetube.它具有结构简单、直观、压力损失小、维修方便等特点。Ithasasimple,intuitivestructure,lowpressurelossandeasymaintenance.转子流量计的特点Featuresofrotorflowmeters转子流量计的特点Featuresofrotorflowmeters

转子流量计适用于测量通过中小管径（DN4～250）的流量，也可以测量腐蚀性介质的流量。

Rotorflowmeterissuitableformeasuringtheflowthroughsmallandmediumpipediameter(DN4~250),canalsomeasuretheflowofcorrosivemedia.其中玻璃管浮子流量计结构简单，成本低，易制成防腐蚀性仪表，但其强度低；Rotorflowmeterissuitableformeasuringtheflowthroughsmallandmediumpipediameter(DN4~250),canalsomeasuretheflowofcorrosivemedia.而金属管浮子流量计可输出标准信号，耐高压，能实现流量的指示、积算、记录、控制和报警等多种功能。Andmetaltubefloatflowmetercanoutputstandardsignal,highpressureresistance,canrealizetheflowofindication,accumulation,record,controlandalarmandotherfunctions.转子流量计的特点Featuresofrotorflowmeters转子流量计安装与使用Rotorflowmeterinstallationanduse仪表安装方向绝大部分浮子流量计必须垂直安装在无振动的管道上，不应有明显的倾斜，流体自下而上流过仪表。Themajorityoffloatflowmetersmustbeinstalledverticallyinavibration-freepipelinewithoutanyobviousinclination,withthefluidflowingthroughthemeterfromthebottomup.中心线与铅垂线间夹角一般不超过5°，高精度（1.5级以上）仪表0≤20°。Floatflowmetercenterlineandtheanglebetweentheplumblinegenerallydoesnotexceed5°,high-precision(morethan1.5grade)instrument0≤20°.（1）仪表安装方向Instrumentinstallationdirection仪表无严格上游直管段长度要求，但也有制造厂要求2～5D（D为连接管管径）长度。Thereisnostrictupstreamstraightpipesectionlengthrequirementfortheinstrument,buttherearemanufacturerswhorequire2to5D(Distheconnectionpipediameter)length.转子流量计安装与使用Rotorflowmeterinstallationanduse应在仪表进水方向的上游装过滤器。Afiltershouldbeinstalledupstreamofthemeterinthedirectionofthewaterintake.带有磁性耦合的金属管浮子流量计用于可能含铁磁性杂质流体时，应在仪表前装磁过滤器。Metaltubefloatflowmeterswithmagneticcouplingshouldbefittedwithamagneticfilterinfrontofthemeterwhenusedwithfluidsthatmaycontainferromagneticimpurities.浮子的洁净程度明显影响测量值，要保持浮子和锥管的清洁，特别是小口径仪表。Thecleanlinessofthefloatobviouslyaffectsthemeasuredvalue,keepthefloatandtheconeclean,especiallyforsmalldiametermeters.（2）用于污脏流体的安装Forinstallationswithdirtyfluids如果测量要求的流量范围度宽，范围度超过10时，经常采用2台以上不同流量范围的玻璃管浮子流量计并联；Ifthemeasurementrequirementsoftheflowrangedegreewide,rangedegreemorethan10,oftenusingmorethan2differentflowrangeofglasstubefloatflowmeterinparallel.也可按所测量择其一台或多台仪表串联，小流量时读取下流量范围仪表示值，大流量时读取大流量仪表示值，串联法比并联法操作简便，不需频繁启闭阀门，但压力损失大。Canalsobemeasuredaccordingtothechoiceofitsoneormoremetersinseries,smallflowratewhenreadingthelowerflowrangemetertoindicatethevalue,thelargeflowratewhenreadingthelargeflowmetertoindicatethevalue,seriesmethodthantheparallelmethodofoperationissimple,donotneedtofrequentlyopenandclosethevalve,butthepressure