《水處理技術(shù)（雙語）》課件-止回閥

Checkvalves止回閥止回閥在管路系統(tǒng)中的主要作用是防止介質(zhì)倒流而造成泵及其驅(qū)動(dòng)電機(jī)機(jī)反轉(zhuǎn)，防止容器內(nèi)介質(zhì)的泄放。止回閥還可用于壓力可能超過主系統(tǒng)壓力的輔助系統(tǒng)管路上Themainroleofcheckvalvesinthepipingsystemistopreventthebackflowofmediaandcausethepumpanditsdrivemotormachinereversal,topreventthereleaseofmediainthecontainer.Checkvalvecanalsobeusedintheauxiliarysystempipelinewherethepressuremayexceedthemainsystempressure.止回閥又稱為逆流閥、逆止閥、背壓閥、單向閥。這類閥門靠管路中介質(zhì)本身的流動(dòng)產(chǎn)生的力而自動(dòng)開啟和關(guān)閉，屬于自動(dòng)閥門的一種。Checkvalveisalsocalledbackflowvalve,checkvalve,backpressurevalve,checkvalve.Thesevalvesrelyontheforcegeneratedbytheflowofthemediumitselfinthepipelineandautomaticallyopenandclose,belongingtoakindofautomaticvalve.止回閥的工作原理Principleofoperationofcheckvalves止回閥的分類Classificationofcheckvalves止回閥根據(jù)其結(jié)構(gòu)和安裝方式可分為旋啟式、升降式、碟式和管道式四種形式。Checkvalvescanbedividedintofourforms:swingtype,lifttype,disctypeandpipelinetypeaccordingtotheirstructureandinstallationmethod.圖為升降式Liftingtype圖為旋啟式Swing-opentype圖為碟式Disc圖為管道式Pipelinetype1.旋啟式止回閥Swing-opencheckvalve止回閥的分類Classificationofcheckvalves旋啟式止回閥的閥瓣呈圓盤狀，繞閥座通道的轉(zhuǎn)軸作旋轉(zhuǎn)運(yùn)動(dòng)，因閥內(nèi)通道成流線型，流動(dòng)阻力比升降式止回閥小，適用于低流速和流動(dòng)不常變化的大口徑場合，但不宜用于脈動(dòng)流，其密封性能不及升降式。Swingcheckvalveflapisdisc-shaped,rotatingmovementaroundtheaxisofthevalveseatchannel,becausethevalvechannelintostreamline,flowresistancethanliftcheckvalveissmall,suitableforlowflowrateandflowdoesnotoftenchangethelargediameteroccasions,butnotforpulsatingflow,itssealingperformanceisnotasgoodaslifttype.旋啟式止回閥分單瓣式、雙瓣式和多瓣式三種。單瓣旋啟式止回閥一般適用于中等口徑的場合，大口徑管路選用單瓣旋啟式止回閥時(shí)，為減少水錘壓力，最好采用能減小水錘壓力的緩閉止回閥；雙瓣旋啟式止回閥適用于大中口徑管路；多瓣旋啟式止回閥適用于大口徑管路。Swingcheckvalveisdividedintosingle,doubleandmulti-flaptypethree.Single-valveswingcheckvalveisgenerallysuitableformediumcaliberoccasions,largediameterpipelineselectionofsingle-valveswingcheckvalve,inordertoreducewaterhammerpressure,itisbesttousetheslow-closingcheckvalvetoreducewaterhammerpressure;double-valveswingcheckvalveforlargeandmediumdiameterpipeline;multi-valveswingcheckvalveforlargediameterpipeline.旋啟式止回閥及其結(jié)構(gòu)示意圖如圖所示。

Swing-opencheckvalveanditsstructureschematicdiagramisshowninthefigure.止回閥的分類Classificationofcheckvalves止回閥的分類Classificationofcheckvalves2.升降式止回閥Liftcheckvalve為閥瓣沿著閥體垂直中心線滑動(dòng)的止回閥。升降式止回閥的閥體形狀與截止閥一樣（可與截止閥通用），其結(jié)構(gòu)與截止閥相似，閥體和閥瓣與截止閥相同。Acheckvalveforwhichthevalveflapslidesalongtheverticalcenterlineofthevalvebody.Thebodyshapeoftheliftcheckvalveisthesameastheglobevalve(canbecommonwiththeglobevalve),itsstructureissimilartotheglobevalve,andthevalvebodyandvalveflaparethesameastheglobevalve.止回閥的分類Classificationofcheckvalves升降式止回閥閥瓣上部和閥蓋下部有導(dǎo)向套筒，閥瓣導(dǎo)向筒可在閥蓋導(dǎo)向筒內(nèi)自由升降。當(dāng)介質(zhì)順流時(shí)，閥瓣靠介質(zhì)推力開啟；Theupperpartofthevalveflapandthelowerpartofthevalvecoverhaveguidesleeves,andthevalveguidecylindercanbefreelyliftedinthevalvecoverguidecylinder.Whenthemediumflow,thevalveflapopensbythemediumthrust.當(dāng)介質(zhì)停流時(shí)，介質(zhì)作用在閥瓣的壓力加上自身重力大于閥前的壓力時(shí)，閥瓣降落在閥座上，起阻止介質(zhì)逆流作用。Whenthemediumstopsflowing,thepressureofthemediumactingonthevalveflapplusitsowngravityisgreaterthanthepressureinfrontofthevalve,thevalveflaplandsonthevalveseatandplaysaroleinstoppingthebackflowofthemedium.止回閥的分類Classificationofcheckvalves直通式升降止回閥介質(zhì)進(jìn)出口通道方向與閥座通道方向垂直；Straightliftcheckvalvemediaimportandexportchanneldirectionandseatchanneldirectionperpendicular對于立式升降式止回閥，其介質(zhì)進(jìn)出口通道方向與閥座通道方向相同，其流動(dòng)阻力較直通式小，升降式止回閥及其結(jié)構(gòu)示意圖如圖所示。升降式止回閥只能安裝在水平管道上。Forverticalliftcheckvalve,itsmediaimportandexportchanneldirectionandseatchanneldirectionisthesame,itsflowresistanceissmallerthanthestraight-throughtype,liftcheckvalveanditsstructureschematicdiagramasshowninthefigure.Liftcheckvalvecanonlybeinstalledonthehorizontalpipeline.為閥瓣圍繞閥座內(nèi)的銷軸旋轉(zhuǎn)的止回閥。碟式止回閥結(jié)構(gòu)簡單，流阻較小，水錘壓力亦較小。但只能安裝在水平管道上，密封性較差。Itisacheckvalvewherethevalveflaprotatesaroundapininthevalveseat.Thedisccheckvalvehasasimplestructure,lowflowresistance,andlowwaterhammerpressure.However,itcanonlybeinstalledonhorizontalpipingandhaspoorsealing.碟式止回閥如圖所示。Thedisctypecheckvalveisshowninthefigure.止回閥的分類Classificationofcheckvalves4.管道式止回閥Pipe-typecheckvalve止回閥的分類Classificationofcheckvalves3.碟式止回閥Disctypecheckvalve管道式止回閥為閥瓣沿閥體中心線滑動(dòng)的閥門。管道式止回閥是一種新型閥門，具有體積小，重量較輕，加工工藝性好的特點(diǎn)，是止回閥的發(fā)展方向之一。Pipe-typecheckvalveisavalvewhosevalveflapslidesalongthecenterlineofthevalvebody.Pipe-typecheckvalveisanewtypeofvalvewithsmallvolume,lightweightandgoodprocessability,whichisoneofthedevelopmentdirectionofcheckvalve.但其流體阻力系數(shù)比旋啟式止回閥略大，管道式止回閥如圖所示。However,itsfluidresistancecoefficientisslightlylargerthanthatofswingcheckvalve,pipe-typecheckvalveasshowninthefigure.止回閥安裝與維護(hù)Checkvalveinstallationandmaintenance止回閥的安裝應(yīng)注意以下事頂：Theinstallationofthecheckvalveshouldpayattentiontothefollowingthingstop.（1）在管線中不要使止回閥承受重量，大型的止回閥應(yīng)獨(dú)立支撐，使之不受管系統(tǒng)產(chǎn)生的壓力的影響；Donotsubjectcheckvalvestoweightinthepipeline,andlargecheckvalvesshouldbeindependentlysupportedsothattheyarenotaffectedbythepressuregeneratedbythepipesystem.（2）安裝時(shí)，注意介質(zhì)流動(dòng)的方向應(yīng)與閥體所標(biāo)箭頭方向一致；Wheninstalling,notethatthedirectionofmediaflowshouldbeconsistentwiththedirectionofthearrowmarkedonthevalvebody.圖為止回閥的安裝示意圖Installationdiagramofcheckvalve止回閥安裝與維護(hù)Checkvalveinstallationandmaintenance（3）升降式垂直瓣止回閥應(yīng)安裝在垂直管道上；Liftingverticalflapcheckval