全文预览已结束
下载本文档
版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
performance,form17pressurecomparingtheperformanceofadoubleinletcyclonewithPowderTechnology145(2004)operation.However,theincreasingemphasisonenviron-mentprotectionandgassolidseparationisindicatingthatfinerandfinerparticlesmustberemoved.Tomeetthischallenge,theimprovementofcyclonegeometryandper-formanceisrequiredratherthanhavingtoresorttoalterna-tiveunits.Manyresearchershavecontributedtolargevolumeofworkonimprovingthecycloneperformance,byintroducingnewinletdesignandoperationvariables.Theseincludestudiesoftestingacyclonicfractionatorforresearchers,wasdeveloped,andtheexperimentalstudyonaddressingtheeffectofinlettypeoncycloneperformanceswaspresented.2.ExperimentalThreekindsofcycloneseparatorswithvariousinletgeometries,includingconventionaltangentialsingleinlethavebecameoneofmostimportantparticleremovaldevicethatpreferablyisutilizedinbothengineeringandprocesscleanairbyLimetal.6.Inthispaper,thenewinlettype,whichisdifferenttypeofinletfromthatusedbyformersimplicitytofabricate,lowcosttooperate,andwelladapt-abilitytoextremelyharshconditions,cycloneseparatorsKeywords:Cyclone;Symmetricalspiralinlet;Collectionefficiency;Pressuredrop1.IntroductionCycloneseparatorsarewidelyusedinthefieldofairpollutioncontrolandgassolidseparationforaerosolsamplingandindustrialapplications1.Duetorelative2,developingamathematicmodeltopredictthecollectionefficiencyofsmallcylindricalmultiportcyclonebyDeOtte3,testingamultipleinletcyclonesbasedonLappletypegeometrybyMooreandMcfarland4,designingandtestingarespirablemultiinletcyclonesamplerthatminimizetheorientationbiasbyGautamandStreenath5,andparticlesizeandflowrateinthispaper.Experimentalresultindicatedthatthesymmetricalspiralinlet(SSI),especiallyCSSIinletgeometry,haseffectonsignificantlyincreasingcollectionefficiencywithinsignificantlyincreasingpressuredrop.Inaddition,theresultsofcollectionefficiencyandpressuredropcomparisonbetweentheexperimentaldataandthetheoreticalmodelwerealsoinvolved.ShortcommuniDevelopmentofasymmetricalcycloneseparatorBingtaoZhao*,HenggenDepartmentofEnvironmentalEngineering,DonghuaUniversityReceived28October2003;receivedinrevisedAvailableonlineAbstractThreecycloneseparatorswithdifferentinletgeometryweredesigned,directsymmetricalspiralinlet(DSSI),andaconvergingsymmetricalperformancecharacteristics,includingthecollectionefficiencyandsamplingthatusedmultipleinletvanesbyWeddingetal.*Correspondingauthor.Tel.:+86-21-62373718;fax:+86-21-62373482.E-mailaddress:(B.Zhao).Shen,YanmingKangNo.1882,YananRd.,Shanghai,Shanghai200051,China24February2004;accepted3June2004July2004whichincludeaconventionaltangentialsingleinlet(CTSI),aspiralinlet(CSSI).Theeffectsofinlettypeoncyclonedrop,wereinvestigatedandcomparedasafunctionofcationspiralinlettoimprove4750(CTSI),directsymmetricalspiralinlet(DSSI),andconverg-ingsymmetricalspiralinlet(CSSI),weremanufacturedandstudied.ThegeometriesanddimensionsthesecyclonesarepresentedinFig.1andTable1.Toexaminetheeffectsofinlettype,allotherdimensionsweredesignedtoremainthesamebutonlytheinletgeometry.Thepressuredropsweremeasuredbetweentwopressuretapsonthecycloneinletandoutlettubebyuseofadigitalby0.151.15%and0.402.40%inthetestedvelocityrange.Fig.4(a)(d)comparesthegradecollectionefficiencyofthecycloneswithvariousinlettypesattheflowrateof3Fig.2.Schematicdiagramofexperimentalsystemsetup.B.Zhaoetal./PowderTechnology145(2004)475048micromanometer(SINAP,DP1000-IIIC).Thecollectionefficiencywascalculatedbytheparticlesizedistribution,byuseofmicroparticlesizeanalyzer(SPSI,LKY-2).DuetohavingthesamesymmetricalinletinModelBorC,theflowrateofeachinletofmultiplecyclonewasequaltoanotherandcontrolledbyvalve;twonozzle-typescrewfeederswereusedinsameoperatingconditionstodispersetheparticleswithaconcentrationof5.0g/m3ininlettube.Thesolidparticlesusedweretalcumpowderobeyedbylog-normalsizedistributionwithskeletaldensityof2700kg/m3,massmeandiameterof5.97Am,andgeometricdeviationof2.08.Themeanatmosphericpressure,ambienttemperature,andrelativehumidityduringthetestswere99.93kPa,293K,andlessthan75%,respectively.3.ResultsanddiscussionTheexperimentalsystemsetupisshowninFig.2.Fig.1.Schematicdiagramofcyclonesgeometries:(a)conventionaltangentialsingleinlet,ModelA;(b)directsymmetricalspiralinlet,ModelB;(c)convergingsymmetricalspiralinlet,ModelC.3.1.CollectionefficiencyFig.3showsthemeasuredoverallefficienciesofthecyclonesasafunctionofflowratesorinletvelocities.Itisusuallyexpectedthatcollectionefficiencyincreasewiththeentrancevelocity.However,theoverallefficiencyofthecyclonewithsymmetricalspiralinletbothModelsBandCwasalwayshigherthantheefficiencyofthecyclonewithconventionalsingleinletModelAatthesamevelocity;andespecially,thecyclonewithCSSI,ModelChasahighestoverallefficiency.TheseeffectsofimprovedinletgeometrycontributetotheincreaseinoverallefficiencyofthecycloneTable1Dimensionsofcyclonesstudied(unit:mm)DDehHBSab3001504501200112515015060388.34,519.80,653.67,and772.62m/h,withtheinletvelocitiesof11.99,16.04,20.18,and23.85m/s,respectively.Asexpected,thefrictionalefficienciesofallthecyclonesareseentoincreasewithincreaseinparticlesize.Theshapesofthegradecollectionefficiencycurvesofallmodelshaveaso-calledSshape.ThefrictionefficienciesoftheDSSI(ModelB)andCSSIcyclones(ModelC)aregreaterby210%and520%thanthatfortheCTSIcyclone(ModelA),respectively.Thisindicatesthattheinlettypeorgeometrytothecycloneplaysanimportantroleinthecollectionefficiency.Itwasexpectedthatparticlesintroducedtothecyclonewithsymmetricalspiralinlet(ModelsBandC)wouldeasilybecollectedonthecyclonewallbecausetheyonlyhavetomoveashortdistance,andespecially,theCSSI(ModelC)changestheparticleconcentrationdistributionandmakestheparticlepreseparatedfromthegasbeforeenteringthemainbodyofcyclone.Fig.5comparestheexperimentaldataataflowrateof653.67m3/h(inletvelocityof20.18m/s)withexistingclassicaltheories711.Apparently,theefficiencycurvesbasedonMothesandLofflermodelandIoziaandLeithsmethodmatchtheexperimentalcurvesmuchcloserthanothertheoriesdo.ThisresultcorrespondswiththestudycarriedoutbyDirgoandLeith12andXiangetal.13.Fig.3.Overallefficiencyofthecyclonesatdifferentinletvelocities.velocityB.Zhaoetal./PowderTechnology145(2004)475049Fig.4.Gradeefficiencyofthecyclonesatdifferentinletvelocities.(a)Inlet(d)Inletvelocity=23.85m/s.Thecomparisonshowthatsomemodelcanpredictatheoreticalresultthatclosedtheexperimentaldata,butthechangesofflowpatternandparticleconcentrationdistribu-tioninducedbysymmetricalspiralinlethavingeffectsoncycloneperformancewerenottakenintoaccountadequatelyindevelopedtheories.Toexaminetheeffectsofthesymmetricalspiralinletoncycloneperformancemoreclearly,Fig.6wasprepared,depictingthe50%cutsizeforallmodelswithvaryingtheflowrateorinletvelocity.The50%cutsizeofModelsCandBarelowerthanthatofModelAatthesameinletFig.5.Comparisonofexperimentalgradeefficiencywiththeories.=11.99m/s.(b)Inletvelocity=16.04m/s.(c)Inletvelocity=20.18m/s.velocity.Astheinletvelocityisdecreased,the50%cutsizeisapproximatelydecreasedlinearly.Withinletvelocity20.18m/s,forexample,thedecreaserateof50%cutsizeisupto9.88%forModelBand24.62%forModelC.Thisindicatedthatthenewinlettypecanhelptoenhancethecyclonecollectionefficiency.3.2.PressuredropThepressuredropacrosscycloneiscommonlyexpressedasanumbergasinletvelocityheadsDHnamedthepressureFig.6.The50%cutsizeofthecyclones.inletvelocityarepresentedinTable2.Obviously,higherpressuredropisassociatedwithhigherBarth5.18B.Zhaoetal./PowderTechnology145(2004)475050flowrateforagivencyclone.However,specifyingaflowrateorinletvelocity,thedifferenceofpressuredropcoef-ficientbetweenModelsB,C,andAislesssignificant,andvariedbetween5.21and5.76,withanaveragevalue5.63,forModelB,5.225.76,withanaveragevalue5.67,forModelC,and5.165.70,withanaveragevalue5.55,forModelA,calculatedbyregressionanalysis.Thisisanimportantpointbecauseitispossibletoincreasethecyclonecollectionefficiencywithoutincreasingthepressuredropsignificantly.Theexperimentaldataofpressuredropwerealsocomparedwithcurrenttheories1420,andresultsarepresentedinTable3.TheresultsshowthatthemodelofAlexanderandBarthprovidedthebetterfittotheexperimentaldata,althoughforsomecyclonesthemodelsofShepherdandLappleandDirgopredictedequallywell.4.ConclusionsAnewkindofcyclonewithsymmetricalspiralinletdropcoefficient,whichisthedivisionofthepressuredropbyinletkineticpressureqgmi2/2.Thepressuredropcoeffi-cientvaluesforthethreecyclonescorrespondingtodifferentTable2PressuredropcoefficientofthecyclonesCycloneInletvelocity(m/s)model11.9916.04A5.165.18B5.215.27C5.225.35Table3ComparisonofpressuredropcoefficientwiththeoriesTheoryShepherdAlexanderFirstStairmandValue6.405.626.185.01(SSI)includingDSSIandCSSIwasdeveloped,andtheeffectsoftheseinlettypesoncycloneperformanceweretestedandcompared.ExperimentalresultsshowtheoverallefficiencytheDSSIcycloneandCSSIisgreaterby0.151.15%and0.402.40%thanthatforCTSIcyclone,andthegradeefficiencyisgreaterby210%and520%.Inaddition,thepressuredropcoefficientis5.63forDSSIcyclone,5.67forCSSI,and5.55forCTSIcyclone.Despitethatthemultipleinletincreasesthecomplicityandthecostofthecycloneseparators,thecycloneswithSSI,especiallyCSSI,canyieldabettercollectionefficiency,obviouslywithaminorincreaseinpressuredrop.Thispresentsthepossi-bilityofobtainingabetterperformancecyclonebymeansofimprovingitsinletgeometrydesign.References1Y.F.Zhu,K.W.Lee,Experimentalstudyonsmallcyclonesoperatingathighflowrates,AerosolSci.Technol.30(10)(1999)13031315.2J.B.Wedding,M.A.Weigand,T.A.Carney,A10Amcutpointinletforthedichotomoussampler,Environ.Sci.Technol.16(1982)602606.3R.E.DeOtte,Amodelforthepredictionofthecollectionefficiencycharacteristicsofasmall,cylindricalaerosolsamplingcyclone,Aero-solSci.Technol.12(1990)10551066.4M.E.Moore,A.R.Mcfarland,Designmethodologyformultipleinletcyclones,Environ.Sci.Technol.30(1996)271276.5M.Gautam,A.Streenath,Performanceofarespirablemulti-inletcyclonesampler,J.AerosolSci.28(7)(1997)12651281.6K.S.Lim,S.B.Kwon,K.W.Lee,Characteristicsofthecollectionefficiencyforadoubleinletcyclonewithcleanair,J.AerosolSci.34(2003)10851095.7D.Leith,W.Licht,Thecollectionefficiencyofcyclonetypeparticlecollectors:anewtheoreticalapproach,AIChESymp.Ser.68(126)(1972)196206.8P.W.Dietz,Collectionefficiencyofcycloneseparators,AIChEJ.27(6)(1981)888892.9H.Mothes,F.Loffler,Predictionofparticleremovalincyclonesepa-rators,Int.Chem.Eng.28(2)(1988)231240.10D.L.Iozia,D.Leith,Thelogisticfunctionandcyclonefractionalefficiency,AerosolSci.Technol.12(1990)5
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 2024-2029年调心滚珠轴承行业市场现状供需分析及市场深度研究发展前景及规划投资研究报告
- 2024-2029年血糖仪行业市场现状供需分析及重点企业投资评估规划分析研究报告
- 2024-2029年蛋白质零食行业市场现状供需分析及重点企业投资评估规划分析研究报告
- 2024-2029年蓝光播放器行业市场现状供需分析及重点企业投资评估规划分析研究报告
- 2024-2029年落地式离心机行业市场现状供需分析及市场深度研究发展前景及规划投资研究报告
- 2024-2029年药品玻璃瓶行业市场现状供需分析及重点企业投资评估规划分析研究报告
- 2024-2029年茶几行业风险投资运行分析及运作模式与投融资研究报告
- 2024-2029年花洒行业市场现状供需分析及重点企业投资评估规划分析研究报告
- 2024-2029年船舶推进系统行业市场现状供需分析及重点企业投资评估规划分析研究报告
- 2024-2029年航空轴承系统行业市场现状供需分析及市场深度研究发展前景及规划投资研究报告
- 航海英语会话(一)
- 学校预防接种证查验工作方案
- 设立种子管理公司可行性研究报告
- 医学装备使用安全培训
- 湖南省长沙市长郡梅溪湖中学2024届中考试题猜想化学试卷含解析
- 实验室安全风险点及控制措施统计表(全新完整版)
- 2023医院医疗机构手术分级管理制度(完整版)
- 领导者的创新能力
- 工程招标代理服务投标方案(技术方案)
- 网络系统管理与维护实训
- 供应商考察申请表
评论
0/150
提交评论