培训教材-泵

企业机密请勿外传DEFINITIONANDPURPOSETYPESPUMPS企业机密请勿外传泵定义及用途泵企业机密请勿外传PURPOSEThepurposeofapumpistofacilitatethemovementofliquidsandliquidmixturesfromonelocationtoanother.Thismovementmaybefromonecontainedsystemtoanother,fromacontainedtoanopensystem,anopensystemtoacontainedsystem,oranopensystemtoanother.Differentpumpsaccomplishthismovementindifferentmanners.Thefirstpumpswereinventedover2000yearsago,andtheirdesignhasbeenconstantlyimprovedtowhatwehaveatthepresenttime.Acentrifugalpump,oneofthemostcommontypesofpump,wasinventedintheseventeenthcentury.Regardlessofthetypeofpumpanditsapplication,theabilitytomoveliquidmaterialfromonelocationtoanotherwithmechanicaldevicesisacriticalpartofthemanufacturingprocess.Pumpsaredesignedtoaddenergytotheliquidtheyaretransporting.泵.用途企业机密请勿外传用途泵的用途是将液体或液态混合物将一个地点输送至另一地点。泵在输送中给液体添加外力。这种输送可以从一个独立系统到另外一个独立系统，从独立系统到开放系统，从开放系统到独立系统，从开放系统到开放系统。不同类型的泵有不同的输送方式。第一台泵出现在2000多年前，并不断改进至今。离心泵是最常见的泵类型之一，发明于17世纪。泵的应用是制造业发展中重要的里程碑。泵.用途企业机密请勿外传TYPESTwoofthemostcommontypesofpumpsaredynamic(centrifugal)andpositivedisplacement(PD).Withineachgroupareseveralsubtypes.Therearebothverticalandhorizontalcentrifugalpumps,andtherearesingle-stageandmultistageaxialpumps.InthePDrotarytypegroup,therearescrew,externalgear,internalgear,slidingvane,flexiblevane,andlobepumps;inthePDreciprocatinggrouparepiston,plunger,anddiaphragmpumps.Eachofthesepumptypeshasdifferentcharacteristicsandcapabilities,anddependingontheparticularneedoftheprocess,theonemostsuitedtotheneedswillbeused.Therearedistinctadvantagesforeachgroupofpumps;centrifugalpumpsaregenerallylessexpensivetopurchaseandmaintain,easiertoperformrepairsormodificationson,moreadaptabletofitdifferentpowersituations,andwilloperateoverawidevarietyofconditions.PDpumpsaredesignedtodeliverconsistent,preciseamountsofliquidtoapplicationsthatrequiresuchprecision.Pumpsaresuppliedenergybyvariousmeans.Electricmotorsarewidelyusedtosupplythisenergy,butmanyothersourcescanalsobeused.Steamcanbethedrivingforcethroughtheuseofaturbine;compressedair,internalcombustionengines,andhydraulicpowerarealsousedtosupplyenergyforpumps.泵.类型企业机密请勿外传类型泵.类型最常见的泵两种类型是离心式和正位移式（PD）。每一族中又有许多子类型。离心泵又分垂直的、水平的，单级的、多级的轴流泵。在正位移回转泵中，有螺杆式、内部齿轮和外部齿轮、滑片式和挠性泵以及凸轮泵。在正位移往复泵中有活塞式、柱塞式和隔膜泵。每一组不同泵有不同的特点和功效，根据工艺特殊需要，选用适合的泵。每组泵有明显的优点，离心泵价格便宜、维护简单、容易改装，更适合于安装于不同的电力工况，适用范围更广泛。正位移泵被设计来传送持续的精确数量的液体满足精确地要求。泵驱动方式多种多样。电机的应用最广泛。蒸汽、压缩空气、内燃机、水动力也可以用来为泵提供动力。企业机密请勿外传Centrifugalpumpsarethemainclassinthedynamicgroupofpumps.Theyarethemostcommonpumpusedthroughouttheindustry.Thesepumpsmoveliquidsbycentrifugalforceandthedesignofthepumpsvolute.Theliquidspuninsidethebodyofapumpinacircularmotionbyitsimpellerpropelsitoutwardintoadischargeareacalledavolute.Thecentrifugalforceaddsenergytotheliquid,andtheshapeofthevolutecausestheliquidleavingittoslowdown,whichcreatesadditionalpressure.(Bernouli’sprinciple:inaclosedsystem,changesinpressurearerelatedtochangesinvelocity,i.e.whenvelocitydecreases,pressureincreasesandviceversa.)Theadditionofenergyfromthespinningimpellerinconjunctionwiththechangeinvelocityaddspressuretotheliquidbeingpumped,allowingthepumptomovetheliquid.泵.离心泵企业机密请勿外传动力泵中最主要的就是离心泵，也是工厂中普遍使用的一种泵。这种泵主要靠离心力和泵的涡形来输送流体。液体在叶轮的推动下由中心流向外缘。在离心力的作用下，液体从叶轮中心被抛向外缘时获得能量，以高速离开叶轮外缘进入蜗形泵壳。在蜗壳中，液体由于流道的逐渐扩大而减速，又将部分动能转变为静压能，最后以较高的压力流入排出管道。贝努力定理认为：在密闭系统中，压力变化相应的速度就会改变，速度降低，压力增加，反之亦然。速度的改变使液体获得更高的能量，以较高的压力将液体输出。泵.离心泵企业机密请勿外传Inorderforacentrifugalpumptofunctionproperly,thepumpmustbefullofliquid(primed),anditmusthavesufficientsuction(inlet)pressure.Theliquidsupplytothesuctionofthepumpispushedintotheimpeller.Theforcethatpushestheliquidiscallednetpositivesuctionhead(NPSH)whichisnormallycalculatedinfeetofliquid.Liquidsexertpressurebasedontheheightandweightoftheliquid.Centrifugalpumpsaredesignedtooperateinspecificservicesatspecifiedrates.Acharacteristiccurveisdevelopedtoshowwhatthebestoperatingconditionsforthatparticularpumpare.ThechartcomparesNPSH,andflowratestoindicatetheoptimumoperatingefficiencyforthepump.泵.离心泵企业机密请勿外传为了使离心泵正常工作，泵内必须充满液体，而且有足够的吸入压。吸入泵内的液体被推入叶轮，这种推动力就叫做净吸入扬程。液体的出口压力由液体的高度和重量决定。离心泵在特定速度下应用于特定的设备。离心泵的特征曲线可以表明泵的最佳工作条件。可以根据泵的特征曲线和静压头、流速来确定泵的最佳操作效率。泵.离心泵企业机密请勿外传Thebasicpartsofacentrifugalpumpare:outercasing(body)-thisisdesignedtoenhanceliquidflow.Itcontainstheliquid,housesthevolute,andholdstheinternalandexternalpartsofthepumptogether.Itisnormallyintwopieces,withagasket,orsealingmaterialbetweenthetwopieces.volute-agraduallywideningcavityinsidethecasingofthepump.inlet-commonlyreferredtoasthesuctionorsuctioneye;pipingattachedtothecenterbringsliquidintothecenteroftheimpeller.outlet-commonlyreferredtoasthedischarge,itreceivestheliquidpropelledfromthevolute.Thedischargehasasmallerdiameterthantheinletandbecauseofthat,velocityagaindecreases,whichincreasespressure.impeller-acirculardeviceresemblingawheelwithcurvedbladesattachedtotheshaftofthepumpwhichrotatesinsidethecasing,comesintocontactwiththeliquidenteringthepumpinlet,andprovidesrotationalenergytotheliquid.泵.离心泵构成企业机密请勿外传离心泵的主要部件：泵壳-提高液体流速，里面是液体、蜗壳，泵壳将内部和外部的部件连接到一起,主要有两部分，这两部分之间是垫圈或者说是密封材料。蜗壳-泵体内逐渐扩大的一个气腔。吸入口-液体吸入