《水處理技術（雙語）》課件-轉子流量計

Rotorflowmeters轉子流量計轉子流量計的特點Featuresofrotorflowmeters轉子流量計又稱浮子流量計，浮子流量計作為直觀流動指示或測量精確度要求不高的現(xiàn)場指示儀表，它可測量液體、氣體和蒸汽的流量，被廣泛地用在電力、石化、化工、冶金、醫(yī)藥等流程工業(yè)和污水處理等方面。Rotorflowmeter,alsoknownasfloatflowmeter,floatflowmeterasanintuitiveflowindicationormeasurementaccuracyrequirementsarenothighfieldindicationinstrument,itcanmeasuretheflowofliquid,gasandsteam,iswidelyusedinelectricpower,petrochemical,chemical,metallurgical,pharmaceuticalandotherprocessindustriesandsewagetreatment.其特點有：Itscharacteristicsare:轉子流量計的特點Featuresofrotorflowmeters壓力損失小且恒定smallandconstantpressurelosses測量范圍比較寬

arelativelywidemeasuringrange.量程比1:10arangeratioof1:10.工作可靠且刻度線性，reliableoperationandlinearscale.使用維修方便，對儀表前后直管段長度要求不高；easytouseandmaintain,withlowrequirementsforthelengthofthestraightpipesection

beforeandaftertheinstrument.

但受被測液體的密度、黏度、純凈度以及溫度、壓力的影響，也受安裝垂直度的影響，其測量精確度為±2％左右。However,itisaffectedbythedensity,viscosityandpurityoftheliquidbeingmeasuredaswellasthetemperatureandpressure,andalsobytheverticalityoftheinstallation,anditsmeasurementaccuracyisaround±2%.轉子流量計工作原理Rotorflowmeterworkingprinciple

浮子流量計的流量檢測元件是由一根自下向上擴大的垂直錐形管和一個沿著錐管軸上下移動的浮子組所組成。工作原理如圖所示。Theflowdetectionelementofafloatflowmeterconsistsofaverticalconicaltubethatexpandsfromthebottomupwardsandasetoffloatsthatmoveupanddownalongtheaxisoftheconicaltube.Theoperatingprincipleisshowninthediagram.被測流體從下向上經過錐管1和浮子2形成的環(huán)隙3時，浮子上下端產生差壓形成浮子上升的力，當浮子所受上升力大于浸在流體中浮子重量時，浮子便上升，環(huán)隙面積隨之增大，環(huán)隙處流體流速立即下降，浮子上下端差壓降低，作用于浮子的上升力亦隨著減少，直到上升力等于浸在流體中浮子重量時，浮子便穩(wěn)定在某一高度。Themeasuredfluidfromthebottomupthroughtheconetube1andfloat2toformtheringgap3,thefloatupperandlowerendofthedifferentialpressuretoformthefloatrisingforce,whenthefloatbytherisingforceisgreaterthantheweightofthefloatimmersedinfluid,thefloatwillrise,theareaoftheringgapthenincreases,thefluidflowrateattheringgapimmediatelydrop,thefloatupperandlowerendofthedifferentialpressuredecreases,therisingforceonthefloatalsodecreases,untiltherisingforceisequaltothefloatimmersedinfluidWhentheweightofthefloatisimmersedinthefluid,thefloatwillbestabilizedatacertainheight.浮子在錐管中高度和通過的流量有對應關系。Thereisacorrespondencebetweentheheightofthefloatinthe

taperedtubeandtheflowratethroughit轉子流量計工作原理Rotorflowmeterworkingprinciple轉子流量計工作原理Rotorflowmeterworkingprinciple體積流量

的基本方程式為：Thebasicequationforvolumetricflow

isWhenthefloatisanon-solidcorehollowstructure,thebasicequationis轉子流量計工作原理Rotorflowmeterworkingprinciple式中α－儀表的流量系數(shù)，因浮子形狀而異；whereα-theflowcoefficientoftheinstrument,whichvariesaccordingtotheshapeofthefloat.

ΔF-流通環(huán)形面積m2;

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

g-accelerationofgravity,m/s2.Vf-浮子體積，如有延伸體亦應包括，m3;

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

Pf-densityoffloatmaterial,kg/m3.

P-被測流體密度，如為氣體是在浮子上游橫截面上的密度，kg/m3。

P-densityofthefluidbeingmeasured,inthecaseofagasisthedensityinthecross-sectionupstreamofthefloat,kg/m3;Ff-一浮子工作直徑(最大直徑)處的橫截面積，㎡

Ff-cross-sectionalareaattheworkingdiameterofthefloat(maximumdiameter),m2.Gf-一浮子質量，kg

Gf-floatmass,kg.轉子流量計工作原理Rotorflowmeterworkingprinciple流通環(huán)形面積與浮子高度之間的關系如式（3-3）所示，當結構設計已定，則d、β為常量。Therelationshipbetweentheflow-throughannulusareaandthefloatheightisshowninequation(3-3).Whenthestructuraldesignhasbeendetermined,thendandβareconstants.式中有h的二次項，一般不能忽略此非線性關系，只有在圓錐角很小時，才可視為近似線性。Thereisaquadratictermofhintheequation,andthisnon-linearrelationshipcannotgenerallybeignored,andcanonlybeconsideredapproximatelylinearwhentheconeangleisverysmall.轉子流量計工作原理Rotorflowmeterworkingprinciple式中d---浮子最大直徑（即工作直徑），m；

whered-themaximumdiameterofthefloat(i.e.theworkingdiameter),m.h--浮子從錐管內徑等于浮子最大直徑處上升高度，m；h-heightofriseofthefloatfromtheinnerdiameteroftheconetubeequaltothemaximumdiameterofthefloat,m.

β－錐管的圓錐角；β-coneangleoftheconetube.a，b-常數(shù)a,b-constants透明錐形管浮子流量計如圖所示。Thetransparentconicaltubefloatflowmeterisshowninthediagram.透明錐形管用得最普遍的由硼硅玻璃制成，習慣簡稱玻璃管轉子流量計。Themostcommonlyusedtransparentconicaltubeismadeofborosilicateglassandiscustomarilyreferredtoasaglasstuberotameter.流量分度直接刻在錐管外壁上，也有在錐管旁另裝分度標尺。Theflowisgradeddirectlyontheouterwalloftheconicaltube,butthereisalsoaseparategraduationscaleinstallednexttotheconicaltube.（1）玻璃管轉子流量計Glasstuberotameter轉子流量計的特點Featuresofrotorflowmeters轉子流量計的特點Featuresofrotorflowmeters321較大口平滑面內壁儀表采用導桿導向。Largermouthswithsmoothinnerwallgaugesareguidedbyguiderods.錐管內腔有圓錐體平滑面和帶導向棱筋（或平面）兩種。Theinnerchamberoftheconicaltubehasasmoothconesurfaceandaguiderib(orflat)oftwokinds.浮子在錐管內自由移動，或在錐管棱筋導向下移動，Thefloatisfreetomovewithintheconetube,orintheconetuberibbedguidetomove.轉子流量計的類型Typesofrotorflowmeters（2）金屬管轉子流量計Metaltuberotorflowmeter金屬管轉子流量計與玻璃轉子流量計具有相同的測量原理Metaltuberotameterandglassrotameterhavethesamemeasuringprinciple不同的是其錐管由金屬制成，這樣不僅耐高溫、高壓，而且能選擇適當?shù)牟馁|以適合各種腐蝕性介質的流量。Thedifferenceisthatitsconicaltubeismadeofmetal,sothatitisnotonlyresistanttohightemperatureandpressure,butalsoabletochoosetheappropriatematerialtosuittheflowofvariouscorrosivemedia.轉子流量計的類型Typesofrotorflowmeters浮子的位移量與流量的大小成比例，通過磁耦合系統(tǒng)，以不同接觸方式，將浮子位移量傳給指示器指示出流量的大小，并通過轉換器，將流量值轉換成標準的電遠傳信號，從而實現(xiàn)遠距離顯示、記錄、積算和控制功能。Thedisplacementofthefloatisproportionaltothesizeoftheflow.Throughthemagneticcouplingsystem,thefloatdisplacementistransmittedtotheindicatorindifferentcontactwaystoindicatethesizeoftheflow,andthroughtheconverter,theflowvalueisconvertedintoastandardelectricalremotesignal,thusachievingremotedisplay,recording,accumulationandcontrolfunctions.流量計主要由傳感器（測量管及浮子）和信號變送器（指示器）兩大基本部分組成：Theflowmeterconsistsoftwobasicparts:thesensor(measuringtubeandfloat)andthesignaltransmitter(indicator).金屬管轉子流量計在指示器的設計上可以為各種應用場合提供可靠適用的功能組合，如現(xiàn)場指針顯示、LCD顯示瞬時和累計流量等。在指示器供電選擇方面有電池供電、24VDC供電、220VAC供電，方式根據現(xiàn)場情況選擇。金屬轉子流量計如圖所示。Metaltuberotameterintheindicatordesigncanbeforavarietyofapplicationstoprovideareliableandsuitablecombinationoffunctions,suchasfieldpointerdisplay,LCDdisplayinstantaneousandcumulativeflow,etc..Intheindicatorpowersupplyoptionsarebatterypowered,24VDCpowered,220VACpowered,thewayaccordingtositeconditionstochoose.Themetalrotameterisshowninthediagram.轉子流量計的類型Typesofrotorflowmeters

轉子流量計是污水處理廠最常用的一種流量計Rotameteristhemostcommonlyusedtypeofflowmeterinwastewatertreatmentplants通過刻有流量標度尺的錐形玻璃管和管內浮子的位置高度，直接觀察管道內流體流量。Thefluidflowinthepipeisdirectlyobservedbymeansofaconicalglasstubeengravedwithaflowscaleandtheheightofthefloatpositioninthetube.它具有結構簡單、直觀、壓力損失小、維修方便等特點。Ithasasimple,intuitivestructure,lowpressurelossandeasymaintenance.轉子流量計的特點Featuresofrotorflowmeters轉子流量計的特點Featuresofrotorflowmeters

轉子流量計適用于測量通過中小管徑（DN4～250）的流量，也可以測量腐蝕性介質的流量。

Rotorflowmeterissuitableformeasuringtheflowthroughsmallandmediumpipediameter(DN4~250),canalsomeasuretheflowofcorrosivemedia.其中玻璃管浮子流量計結構簡單，成本低，易制成防腐蝕性儀表，但其強度低；Rotorflowmeterissuitableformeasuringtheflowthroughsmallandmediumpipediameter(DN4~250),canalsomeasuretheflowofcorrosivemedia.而金屬管浮子流量計可輸出標準信號，耐高壓，能實現(xiàn)流量的指示、積算、記錄、控制和報警等多種功能。Andmetaltubefloatflowmetercanoutputstandardsignal,highpressureresistance,canrealizetheflowofindication,accumulation,record,controlandalarmandotherfunctions.轉子流量計的特點Featuresofrotorflowmeters轉子流量計安裝與使用Rotorflowmeterinstallationanduse儀表安裝方向絕大部分浮子流量計必須垂直安裝在無振動的管道上，不應有明顯的傾斜，流體自下而上流過儀表。Themajorityoffloatflowmetersmustbeinstalledverticallyinavibration-freepipelinewithoutanyobviousinclination,withthefluidflowingthroughthemeterfromthebottomup.中心線與鉛垂線間夾角一般不超過5°，高精度（1.5級以上）儀表0≤20°。Floatflowmetercenterlineandtheanglebetweentheplumblinegenerallydoesnotexceed5°,high-precision(morethan1.5grade)instrument0≤20°.（1）儀表安裝方向Instrumentinstallationdirection儀表無嚴格上游直管段長度要求，但也有制造廠要求2～5D（D為連接管管徑）長度。Thereisnostrictupstreamstraightpipesectionlengthrequirementfortheinstrument,buttherearemanufacturerswhorequire2to5D(Distheconnectionpipediameter)length.轉子流量計安裝與使用Rotorflowmeterinstallationanduse應在儀表進水方向的上游裝過濾器。Afiltershouldbeinstalledupstreamofthemeterinthedirectionofthewaterintake.帶有磁性耦合的金屬管浮子流量計用于可能含鐵磁性雜質流體時，應在儀表前裝磁過濾器。Metaltubefloatflowmeterswithmagneticcouplingshouldbefittedwithamagneticfilterinfrontofthemeterwhenusedwithfluidsthatmaycontainferromagneticimpurities.浮子的潔凈程度明顯影響測量值，要保持浮子和錐管的清潔，特別是小口徑儀表。Thecleanlinessofthefloatobviouslyaffectsthemeasuredvalue,keepthefloatandtheconeclean,especiallyforsmalldiametermeters.（2）用于污臟流體的安裝Forinstallationswithdirtyfluids如果測量要求的流量范圍度寬，范圍度超過10時，經常采用2臺以上不同流量范圍的玻璃管浮子流量計并聯(lián)；Ifthemeasurementrequirementsoftheflowrangedegreewide,rangedegreemorethan10,oftenusingmorethan2differentflowrangeofglasstubefloatflowmeterinparallel.也可按所測量擇其一臺或多臺儀表串聯(lián)，小流量時讀取下流量范圍儀表示值，大流量時讀取大流量儀表示值，串聯(lián)法比并聯(lián)法操作簡便，不需頻繁啟閉閥門，但壓力損失大。Canalsobemeasuredaccordingtothechoiceofitsoneormoremetersinseries,smallflowratewhenreadingthelowerflowrangemetertoindicatethevalue,thelargeflowratewhenreadingthelargeflowmetertoindicatethevalue,seriesmethodthantheparallelmethodofoperationissimple,donotneedtofrequentlyopenandclosethevalve,butthepressure