高速带式输送机的设计 外文翻译.docx

高速带式输送机的设计 外文翻译.docx

《高速带式输送机的设计 外文翻译.docx》由会员分享，可在线阅读，更多相关《高速带式输送机的设计 外文翻译.docx（23页珍藏版）》请在冰豆网上搜索。

高速带式输送机的设计外文翻译

附件A

esignofHighSpeedBeltConveyors

G.Lodewijks,TheNetherlands.

SUMMARY

Thispaperdiscussesaspectsofhigh-speedbeltconveyordesign.Thecapacityofabeltconveyorisdeterminedbythebeltspeedgivenabeltwidthandtroughingangle.Beltspeedselectionhoweverislimitedbypracticalconsiderations,whicharediscussedinthispaper.Thebeltspeedalsoaffectstheperformanceoftheconveyorbelt,asforexampleitsenergyconsumptionandthestabilityofit'srunningbehavior.Amethodisdiscussedtoevaluatetheenergyconsumptionofconveyorbeltsbyusingthelossfactoroftransport.Withvariationofthebeltspeedthesafetyfactorrequirementsvary,whichwillaffecttherequiredbeltstrength.Anewmethodtoaccountfortheeffectofthebeltspeedonthesafetyfactorispresented.Finally,theimpactofthebeltspeedoncomponentselectionandonthedesignoftransferstationsisdiscussed.

1INTRODUCTION

Pastresearchhasshowntheeconomicalfeasibilityofusingnarrower,fasterrunningconveyorbeltsversuswider,slowerrunningbeltsforlongoverlandbeltconveyorsystems.Seeforexample[I]-[5].Today,conveyorbeltsrunningatspeedsaround8m/sarenoexceptions.However,velocitiesover10m/supto20m/saretechnically（dynamically）feasibleandmayalsobeeconomicallyfeasible.Inthispaperbeltspeedsbetweenthe10and20m/sareclassifiedashigh.Beltspeedsbelowthe10m/sareclassifiedaslow.

Usinghighbeltspeedsshouldneverbeagoalinitself.Ifusinghighbeltspeedsisnoteconomicallybeneficialorifasafeandreliableoperationisnotensuredatahighbeltspeedthenalowerbeltspeedshouldbeselected.

Selectionofthebeltspeedispartofthetotaldesignprocess.Theoptimumbeltconveyordesignisdeterminedbystaticorsteadystatedesignmethods.Inthesemethodsthebeltisassumedtobearigid,inelasticbody.Thisenablesquantificationofthesteady-stateoperationofthebeltconveyoranddeterminationofthesizeofconveyorcomponents.Thespecificationofthesteady-stateoperationincludesaquantificationofthesteady-staterunningbelttensionsandpowerconsumptionforallmaterialloadingandrelevantambientconditions.Itshouldberealizedthatfindingtheoptimumdesignisnotaone-timeeffortbutaniterativeprocess[6].

Designfine-tuning,determinationoftheoptimumstartingandstoppingprocedures,includingdeterminationoftherequiredcontrolalgorithms,anddeterminationofthesettingsandsizesofconveyorcomponentssuchasdrives,brakesandflywheels,aredeterminedbydynamicdesignmethods.Inthesedesignmethods,alsoreferredtoasdynamicanalyses,thebeltisassumedtobeathree-dimensional（visco-）elasticbody.Athreedimensionalwavetheoryshouldbeusedtostudytimedependenttransmissionoflargelocalforceanddisplacementdisturbancesalongthebelt[7].Inthistheorythebeltisdividedintoaseriesoffiniteelements.Thefiniteelementsincorporate（visco-）elasticspringsandmasses.Theconstitutivecharacteristicsofthefiniteelementsmustrepresenttherheologicalcharacteristicsofthebelt.Dynamicanalysisproducesthebelttensionandpowerconsumptionduringnon-stationaryoperation,likestartingandstopping,ofthebeltconveyor.

Thispaperdiscussesthedesignofhighbelt-speedconveyors,inparticulartheimpactofusinghighbeltspeedsontheperformanceoftheconveyorbeltintermsofenergyconsumptionandsafetyfactorrequirements.Usinghighbeltspeedsalsorequireshighreliabilityofconveyorcomponentssuchasidlerstoachieveanacceptablecomponentlife.Anotherimportantaspectofhigh-speedbeltconveyordesignisthedesignofefficientfeedinganddischargearrangements.Theseaspectswillbediscussedbriefly.

2BELTSPEED

2.1BELTSPEEDSELECTION

Thelowestoverallbeltconveyorcostoccurintherangeofbeltwidthsof0.6to1.0m[2].Therequiredconveyingcapacitycanbereachedbyselectionofabeltwidthinthisrangeandselectingwhateverbeltspeedisrequiredtoachievetherequiredflowrate.Figure1showsanexampleofcombinationsofbeltspeedandbeltwidthtoachieveSpecificconveyorcapacities.Inthisexampleitisassumedthatthebulkdensityis850kg/m3（coal）andthatthetroughangleandthesurchargeangleare35'and20'respectively.

Figure1:

Beltwidthversusbeltspeedfordifferentcapacities.

Beltspeedselectionishoweverlimitedbypracticalconsiderations.Afirstaspectisthetroughabilityofthebelt.InFigure1thereisnorelationwiththerequiredbeltstrength（rating）,whichpartlydependsontheconveyorlengthandelevation.Thecombinationofbeltwidthandstrengthmustbechosensuchthatgoodtroughabilityofthebeltisensured.Ifthetroughabilityisnotsufficientthenthebeltwillnottrackproperly.Thiswillresultinunstablerunningbehaviorofthebelt,inparticularathighbeltspeeds,whichisnotacceptable.Normally,beltmanufacturersexpectasufficientlystraightrunifapproximately40%ofthebeltwidthwhenrunningempty,makescontactwiththecarryingidlers.Approximately10%shouldmaketangentialcontactwiththecenteridlerroll.

Asecondaspectisthespeedoftheairrelativetothespeedofthebulksolidmaterialonthebelt（relativeairspeed）.Iftherelativeairspeedexceedscertainlimitsthendustwilldevelop.Thisisinparticularapotentialprobleminmineshaftswhereadownwardairflowismaintainedforventilationpurposes.Thelimitinrelativeairspeeddependsonambientconditionsandbulkmaterialcharacteristics.

Athirdaspectisthenoisegeneratedbythebeltconveyorsystem.Noiselevelsgenerallyincreasewithincreasingbeltspeed.Inresidentialareasnoiselevelsarerestrictedtoforexample65dB.Althoughnoiselevelsaregreatlyaffectedbythedesignoftheconveyorsupportstructureandconveyorcovers,thismaybealimitingfactorinselectingthebeltspeed.

2.2BELTSPEEDVARIATION

Theenergyconsumptionofbeltconveyorsystemsvarieswithvariationofthebeltspeed,aswillbeshowninSection3.Thebeltvelocitycanbeadjustedwithbulkmaterialflowsuppliedattheloadingpointtosaveenergy.Ifthebeltisoperatingatfulltonnagethenitshouldrunatthehigh（design）beltspeed.Thebeltspeedcanbeadjusted（decreased）totheactualmaterial（volume）flowsuppliedattheloadingpoint.Thiswillmaintainaconstantfillingofthebelttroughandaconstantbulkmaterialloadonthebelt.Aconstantfillingofthebelttroughyieldsanoptimumloading-ratio,andlowerenergyconsumptionperunitofconveyedmaterialmaybeexpected.Thereductioninenergyconsumptionwillbeatleast10%forsystemswherethebeltspeedisvariedcomparedtosystemswherethebeltspeediskeptconstant[8].

Varyingthebeltspeedwithsuppliedbulkmaterialflowhasthefollowingadvantages:

∙Lessbeltwearattheloadingareas

∙Lowernoiseemission

∙Improvedoperatingbehaviorasaresultofbetterbeltalignmentandtheavoidanceofbeltliftinginconcavecurvebyreducingbelttensions

Drawbacksinclude:

∙Investmentcostforcontrollabilityofthedriveandbrakesystems

∙Variationofdischargeparabolawithbeltspeedvariation

∙Controlsystemrequiredforcontrollingindividualconveyorsinaconveyorsystem

∙Constanthighbeltpre-tension

∙Constanthighbulkmaterialloadontheidlerrolls

Ananalysisshouldbemadeoftheexpectedenergysavingstodeterminewhetheritisworththeeffortofinstallingamoreexpensive,morecomplexconveyorsystem.

3ENERGYCONSUMPTION

Clientsmayrequestaspecificationoftheenergyconsumptionofaconveyorsystem,forexamplequantifiedintermsofmaximumkW-hr/ton/km,totransportthebulksolidmaterialatthedesignspecificationsovertheprojectedroute.Forlongoverlandsystems,theenergyconsumptionismainlydeterminedbytheworkdonetoovercometheindentationrollingresistance[9].Thisistheresistancethatthebeltexperiencesduetothevisco-elastic（timedelayed）responseoftherubberbeltcovertotheindentationoftheidlerroll.Forin-plantbeltconveyors,workdonetoovercomesideresistancesthatoccurmainlyintheloadingareaalsoaffectstheenergyconsumption.Sideresistancesincludetheresistanceduetofrictiononthesidewallsofthechuteandresistancethatoccursduetoaccelerationofthematerialattheloadingpoint.

Therequireddrivepowerofabeltconveyorisdeterminedbythesumofthetotalfrictionalresistancesandthetotalmateriallift.Thefrictionalresistancesincludehysteresislosses,whichcanbeconsideredasviscous（velocitydependent）frictioncomponents.Itdoesnotsufficetolookjustatthemaximumrequireddrivepowertoevaluatewhetherornottheenergyconsumptionofaconveyorsystemisreasonable.Thebestmethodtocomparetheenergyconsumptionofdifferenttransportsystemsistocomparetheirtransportefficiencies.

3.1TRANSPORTEFFICIENCY

Thereareanumberofmethodstocomparetransportefficiencies.ThefirstandmostwidelyappliedmethodistocompareequivalentfrictionfactorssuchastheDINffactor.Anadvantageofusinganequivalentfrictionfactoristhatitcanalsobedeterminedforanemptybelt.Adrawbackofusinganequivalentfrictionfactoristhatitisnota'pure'efficiencynumber.Ittakesintoaccountthemassofthebelt,reducedmassoftherollersandthemassofthetransportedmaterial.Inapureefficiencynumber,onlythemassofthetransportedmaterialistakenintoaccount.

Thesecondmethodistocomparetransportationcost,eitherinkW-hr/ton/kmorin$/ton/km.Theadvantageofusingthetransportationcostisthatthisnumberiswidelyusedformanagementpurposes.Thedisadvantageof