采煤专业毕业设计外文文献翻译高效生产一个关于采煤机截割的次序的问题.docx
《采煤专业毕业设计外文文献翻译高效生产一个关于采煤机截割的次序的问题.docx》由会员分享,可在线阅读,更多相关《采煤专业毕业设计外文文献翻译高效生产一个关于采煤机截割的次序的问题.docx(10页珍藏版)》请在冰豆网上搜索。
采煤专业毕业设计外文文献翻译高效生产一个关于采煤机截割的次序的问题
外文文献翻译
英文原文
HighProductivity—AQuestionofShearerLoaderCuttingSequences
1Abstract
Recently,thefocusinundergroundlongwallcoalmininghasbeenonincreasingtheinstalledmotorpowerofshearerloadersandarmouredfaceconveyors(AFC),moresophisticatedsupportcontrolsystemsandlongerfacelength,inordertoreducecostsandachievehigherproductivity.Theseeffortshaveresultedinhigheroutputandpreviouslyunseenfaceadvancerates.Thetrendtowards“biggerandbetter”equipmentandlayoutschemes,however,israpidlynearingthelimitationsoftechnicalandeconomicalfeasibility.Torealisefurtherproductivityincreases,organisationalchangesoflongwallminingprocedureslooksliketheonlyreasonableanswer.Thebenefitsofopti-misedshearerloadercuttingsequences,leadingtobetterperformance,arediscussedinthispaper.
2Introductions
Traditionally,inundergroundlongwallminingoperations,shearerloadersproducecoalusingeitheroneofthefollowingcuttingsequences:
uni-directionalorbi-directionalcycles.Besidesthesepre-dominantmethods,alternativeminingcycleshavealsobeendevelopedandsuccessfullyappliedinundergroundhardcoalminesallovertheworld.Thehalf-webcuttingcyclease.g.utilizedinRAGCoalInternational’sTwentymileMineinColorado,USA,andthe“Opti-Cycle”ofMatla’sSouthAfricanshortwalloperationmustbementionedinthiscontext.Othermineshavealsotestedsimilarbutmodifiedcuttingcyclesresultinginimprovedoutput,e.g.improvementsintermsofproductiv-ityincreasesofupto40%arethoughtpossible。
Whereasthementionedminesareapplyingthealternativecuttingmethodsaccordingtotheirspe-cificconditions,–e.g.seamheightorequipmentused,–thispaperlookssystematicallyatthediffer-entmethodsfromageneralisedpointofview.Adetaileddescriptionoftheminingcycleforeachcuttingtechnique,includingtheillustrationofproductiveandnon-productivecycletimes,willbefollowedbyabriefpresentationoftheperformedproductioncapacitycalculationandasummaryofthetechnicalrestrictionsofeachsystem.Standardisedequipmentclassesfordifferentseamheightsaredefined,afterthemostsuitableandmostproductiveminingequipmentforeachclassarese-lected.BesidesthetechnicalparametersoftheshearerloaderandtheAFC,thelengthofthelong-wallfaceandthespecificcuttingenergyofthecoalarethemainvariablesforeachheightclassinthemodel.Asaresultofthecapacitycalculations,thedifferentshearercuttingmethodscanbegraphicallycomparedinastandardisedwayshowingtheproductivityofeachmethod.Duetothegeneralchar-acterofthemodel,potentialoptimisations(resultingfromchangesinthecuttingcycleandthebenefitsintermsofhigherproductivityoftheminingoperation)canbederived.
3State-of-the-artofshearerloadercuttingsequences
Thequestion“Whyaredifferentcuttingsequencesappliedinlongwallmining?
”hastobean-swered,beforediscussingthesignificantcharacteristicsintermsofoperationalprocedures.Themajorconstraintsandreasonsfororagainstaspecialcuttingmethodaretheseamheightandhard-nessofthecoal,thegeotechnicalparametersofthecoalseamandthegeologicalsettingofthemineinfluencingthecavingpropertiesaswellasthesubsidenceandespeciallythelengthofthelongwallface.Foreachminingenvironmenttheapplicationofeithersequenceresultsindifferentproductionratesandconsequentlyadvanceratesoftheface.ThecoalflowontotheAFCisanotherpointthatvariesliketheloadsontheshearerloader,especiallytherangingarmsandthestressesandthewearonthepicks.Athoroughanalysisisnecessarytochoosethebest-suitedminingcycle;therefore,generalsolutionsdonotguaranteeoptimalefficiencyandproductivity.
Acategorizationofshearerloadercuttingsequencesisrealisedbyfourmajorparameters.Firstly,onecanseparatebetweenminingmethods,whichminecoalintwodirections–meaningfromtheheadtothetailgateandonthereturnrunaswell–orinonedirectiononly.Secondly,thewaytheminingsequencedealswiththesituationatthefaceends,toadvancefacelineafterextract-ingtheequivalentofacuttingweb,isacharacteristicparameterforeachseparatemethod.Thenec-essarytraveldistancewhilesumpingvariesbetweenthesequences,asdoesthetimeneededtoper-formthistask,too.Anotheraspectdefiningthesequencesistheproportionofthewebcuttingcoalperrun.Whereastraditionallythefullwebwasused,theintroductionofmodernAFCandroofsup-portautomationcontrolsystemsallowsforefficientoperationsusinghalfwebmethods.Theforthparameteridentifyingstateoftheartshearerloadercuttingsequencesistheopeningcreatedperrun.Otherthanthepartialorhalf-openingmethodlikethoseusedinMatla’s“Opti-Cycle”,thecuttingheightisequaltothecompleteseamheightincludingpartingsandsofthangingorfootwallmaterial.
Bi-directionalcuttingsequence
Thebi-directionalcuttingsequence,depictedinFigure1a,ischaracterisedbytwosumpingopera-tionsatthefaceendsinacompletecycle,whichisaccomplishedduringboththeforwardandreturntrip.Thewholelongwallfaceadvanceseachcompletecycleattheequivalentoftwowebdistancesbythecompletionofeachcycle.Theleadingdrumoftheshearercutstheupperpartoftheseamwhilethereardrumcutsthebottomcoalandcleansthefloorcoal.Themaindisadvantagesofthiscuttingmethodarethoughttobetheunproductivetimeresultingfromthefaceendactivitiesandthecomplexoperation.Therefore,thetrendinrecentyearswastoincreasefacelengthtoreducetherelativeimpactofsumpinginfavouroflongerproductiontime.
Uni-directionalcuttingsequence
Incontrasttothebi-directionalmethod,theshearerloadercutsthecoalinonesingledirectionwheninuni-directionalmode.Onthereturntrip,thefloorcoalisloadedandtheflooritselfcleaned.Theshearerhaulagespeedsonthereturntripsarerestrictedonlybytheoperators’movementthroughthelongwallface,orthehaulagemotorsinafullyautomatedoperation.Thesumpingprocedurestartsinneartheheadgate,asshowninFigure1b.Thelowmachineutilisationbecauseofcuttingjustonewebpercycleisthemaindisadvantageoftheuni-directionalcuttingsequence.Besidesthecoalflowcanbequiteirregulardependingonthepositionoftheshearerinthecycle.
Halfwebcuttingsequence
Themainbenefitofhalfwebcuttingsequencesisthereductionofunproductivetimesintheminingcycle,whichresultsinhighmachineutilisation.Thisisachievedbycuttingonlyahalfwebinmidfacewithbi-directionalgatesequencesasshowninFigure2a.Thefullwebisminedatthefaceends,withlowerspeedsallowingfastersheareroperationinbothdirectionsinmidseam.Besidetherealisationofhigherhaulagespeeds,thecoalflowontheAFCismorebalancedforshearerloadertripsinbothdirections.
Half-/partial-openingcuttingsequence
Theadvantageofthehalf-or,moreprecisely,partial-openingcuttingsequenceisthefactthatthefaceisextractedintwopasses.Figure2bshowsthattheupperandmiddlepartoftheseamiscutduringthepasstowardsthetailgate.Whereasthelastpartofthistripfortheequivalentofama-chinelengththeleadingdrumisraisedtocuttherooftoallowtheroofsupporttobeadvanced.Onthereturntripthebottomcoalisminedwiththeadvantageofafreefaceandasmallerproportionoftheleadingdrumcuttingcoal;consequentlyleadingtolessrestrictionsofthehaulagespeedduetothespecificcuttingenergyofthematerial.Theshearersumpsinmidseamneartheheadgatetothefullwebwithoutinvokingunproductivecycletime.Likeforthetripthetailgatetheleadingdrumhastobeloweredamachinelengthaheadofthemaingate.
4Productioncapacitycalculations
Atheoreticalcomparisonoftheproductivitybetweendifferentminingmethodsingeneral,orinthiscasebetweendifferentshearerloadercuttingcycles,isalwaysbasedonnumerousassumptionsandtechnicalandgeologicalrestrictions.Asaresult,thisproductioncapacitycalculationdoesnotclaimtoofferexactresults,althoughitdoesindicateproductivitytrendsandcertainparametersforeachanalysedmethod.
Themodelworkswithso-calledheightclassesvaryingtheseamthicknessesbetween2mand5minstepsof50cm.Equipmentisassignedtoeachclass,havingbeenselectedbylookingatthebest-suitedtechnicalpropertiesavailableonthemarket[4].Apartfromthedefinedequipment,itisassumedthattheseamisflatandnoundulationsorgeologicalfaultsoccur.Inthemodel,theventilationandtheroofsupportsystemrepresentnorestrictionstotheproduction.Sincetheaimofthismodelistoshowwaystofurtherincreasesinlongwallproductivity,thecalculationisbasedonafullyautomatedsystemwithnomanualoperatorsrequiredattheface.ThehaulagespeedofthesheareristhereforeonlyrestrictedbytheAFCcapacity,thecuttingmotorsandthehaulagemotorsrespectively.
Thevariableparametersinthiscomparisonofthefourcuttingsequencesare,(besidesseamthick-ness)thespecificcuttingenergyofthecoaltobecutandthelengthofthelongwallface.Theformervaryingbetween0.2and0.4kWh/m³,thelatterbetween100mand400min50mintervals.The100mshortwallsweredeliberatelyselected,sincetheyarecomingmoreintofocusforvariousreasons.Geotechnicalaspects,likee.g.thecavingabilityofthehangingwallandfaults,restrictlong-wallpanelsinmanyplacestomaximumfacelengthsof150morless,likeinSouthAfricaandGreatBritain.