Opportunities_to_Improve_Energy_Efficiency_on_paper_machine.ppt

Opportunities_to_Improve_Energy_Efficiency_on_paper_machine.ppt

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OPPORTUNITIESTOIMPROVEENERGYEFFICIENCYONPAPERMACHINEDr.VivekKumarDepartmentofPaperTechnologyIITRoorkee,SaharanpurCampusINTRODUCTIONThepapermillareaisamajorenergyconsumerinmostintegratedpulpandpapermills.Energyconsumptionandcostpertonvarywidelyonpapermachines.Millshavedifferentenergycostsbasedonmillconfiguration,vintageofpapermakingequipment,geographiclocation,andotherparameters.Eachmillneedstodevelopanunderstandingofenergycostfactorsbeforepreparinganeffectiveenergyreductionprogram.Techniquesforimprovingenergyefficiencyonpapermachinei.e.,FormingSectionFormingSection,PressingPressingsection,Dryingsection.section,Dryingsection.Optimizeperformanceofequipment.Usesteam,water,air,andvacuumpressuresappropriatetoprocesses.Minimizeenergylosses.Minimizewaterevaporatedinthedryers.HeatRecovery.FORMINGSECTIONVACUUMSYSTEMThevacuumsystemisamonglargestprocessinthepapermillwithrespecttospacerequirements,piping,andenergyusage.Vacuumsystemscanhaveinstalledandrequiredenergyof500to8,000hp.Severalstepsarerequiredtoguaranteethevacuumsystemisoperatingasefficientlyaspossible.Vacuumsystemauditsorsurveys.Routinemaintenanceofvacuumpumpsandauxiliaryequipment,includingbeltandgeardrivesandmotors;ReplacementandcalibrationofgaugesandprocessinstrumentationHOWDOWECONTROLORMINIMIZEWASTEDENERGY?

Vacuumsystemaudits:

Vacuumsystemaudits:

Onceidentified,somevacuumsystemproblemsmaycausehigherenergyusage,costs,andinefficienciesfortheentiresystem.Hotsealwater.Highsealwaterflowduetounregulatedorhighsealwaterpressure.Backpressureonthevacuumpumpsduetosystemdesignoroperationalproblems.Synchronousvs.inductionmotors,whichmayaffectthepowerfactor.VACUUMSYSTEM.Elevatedsealwaterwillreducevacuumpumpefficiencyandwilllowervacuumsystemcapacity.However,therearemethodstoreducesealwaterconsumptionwithoutsacrificingvacuumpumpperformance.Thiscaninvolveawaterrecoveryplanand/orcoolingthewaterwithacoolingtower.Itisimportanttonotethatspecial,dirty-watercoolingtowershavebeensuccessfulinthisapplication.VACUUMSYSTEM.Wemusthavetomaintainavacuumsysteminsuchawaythatitshouldnothavemorethan1psigofbackpressuremeasuredatthepumpdischarge.Alsowehavetomaintainthesystemcleanandthescalebuildupasminimumaspossible.Insystemswhereadischargesumpisused,highwaterlevelswithinthesumpcancausebackpressureaswellascontributetopoorair/waterseparationwithinthesump.VACUUMSYSTEM.MOTORSIZE/VACUUMPUMPHORSEPOWERAnotherissueinvolvingmotorsistheselectionofthemotorsizewithrespecttothevacuumpumphorsepower.Manymillselecttoinstalloversizedmotorsonequipmenttoreducesparepartsandstoreroominventory.Manyvacuumpumpsareinstalledanddrivenwithamotorfromanoldrefinerthatmayhave50%morehorsepowerthanthevacuumpumprequires.Afrequentpracticeistoreplaceacorrectlysizeddrivemotorwithalargersizetoeliminateoverloadingandtrip-outproblems.Thisisanexampleofcorrectingthesymptomratherthansolvingtheproblem.VACUUMSYSTEM.MOTORSIZE/VACUUMPUMPHORSEPOWEROlder,inefficientvacuumpumpsversusnew,moderndesigns;Scalebuild-up;Processcarryoverandhighsealwaterflows;Pipinglossesorpoorsystemdesign.VACUUMSYSTEM.Newerlargerpumpscanreducethequantityofpumpsonapapermachinebyonehalf.Scale,orcalciumcarbonatebuildup,willincreasevacuumpumphorsepowerrequirementsbyasmuchas20%to30%andoftenlocksuptherotorwithinthevacuumpump.Watertreatmentanddescalingprogramsareusefulinthepreventionofscaling.Recirculatedsealwatersystemswithcoolingtowers,haveexperiencedbettercontrolofthewaterqualityforthevacuumpumps.CaseStudyVACUUMSYSTEM.Inoneaudititismentionedas,thetotalvacuumsystempowerconsumptionwas3,040hp.Allowingforperformancetolerancesanddrivelosses,thesystemshouldrequireonly2,775hp.Thisexcessivepowerconsumptionof265hpwasduetoseveralfactorsaffecting.Theproblemsincludedoverloadingduetohighsealwaterflowsandinternalscaling.Vacuumpumpoperatedat11.3in.Hg,Highestvacuumlevelofthewas7.0Hg.Theextrahorsepowertooperatethevacuumpumpat11.3in.Hgrequiredanadditional34hpAnothervacuumpumpwasrequiring36hpmorethannecessaryduetotheincorrectmodelbeinginstalled.Thiswasahighvacuummodel,designedformoreefficientoperationatabove15in.Hg.However,thepumpwasonthelowvacuumpresszoneandoperatedatonly7in.Hg.Alowvacuummodelneededtobeinstalledtoreducehorsepower.Bymakingsomechangesinfeltconditioning,therewasanopportunitytosaveanadditional108hp.REPLACEMENTOFEXISTINGVACUUMPUMPSCurrentSituation:

InPapermachineNo.1twovacuumpumps（capacity1800m3/hr&ratedvacuum400mmHgeach）areprovidedandhavingcommonheader（i.e.forFlatBoxes&uhleBoxes）andconsuming107kWhSuggestion&Benefits:

Asthesuctionvacuumrequirementisonly200mmHg.Itisrecommendedtoinstallanewvacuumpumpofhighercapacity（ratedsuctionvacuum300mmHg,capacity3500m3/hr）inplaceofexisting2vacuumpumps,whichwillconsumeabout65kWh.Savingpotentialis10765=42kWhorRs.8.05lacs/annumagainstinvestmentofRs.3.00lacs.SituationCurrent:

InPapermachineNo.2twovacuumpumps（capacity1800m3/hr&ratedvacuum400mmHgeach）areprovidedandhavingcommonheader（i.e.forFlatBoxes&uhleBoxes）andconsuming77kWh.Suggestion&Benefits:

Asthevacuumrequirementisonly200mmHg.Itisrecommendedtoinstallanewvacuumpumpofhighercapacity（ratedvacuum300mmHg,ratedcapacity3200m3/hr）inplaceofexisting2vacuumpumps,whichwillconsumeabout56kWh.Savingpotentialis7756=21kWhorRs.4.02lacs/annumagainstinvestmentofRs.3.00lacs.CurrentSituation:

InpapermachineNo.4onevacuumpump（KVM900capacity3600m3/hr,Ratedvacuum500mmHg）hasbeeninstalledforuhleBox,whichisconsuming104kWh.Suggestion&Benefits:

AstherequirementofsuctionvacuuminuhleBoxisaround200mmHg.Itissuggestedtoconventitasperthespecificationi.e.Capacity4125m3/hr,Ratedvacuum300mmHg.Atthesespecificationthepowerconsumptionwillbeabout70kWh.Thereforesavingpotentialis10470=34kWhresultinginsavingofRs.6.5lacs/annumagainstinvestmentofRs.5.00lacs.CurrentSituation:

InpapermachineNo.5onevacuumpump（7LVCapacity1410m3/hr,Ratedvacuum660）hasbeeninstalledforflatboxes,whichisconsuming48.7kWhpower.Suggestion&Benefits:

Astherequirementofsuctionvacuumisonly200mmHginflatboxes,itissuggestedtoreplaceexistingvacuumpumpwithKVM300（Capacity1500m3/hr,Ratedvacuum300mmHg）,whichwillconsumeonly24.5kWhpower.Thereforesavingpotentialisabout48.7-24.5=24kWhresultinginsavingofRs.4.6lacs/annumagainstinvestmentofRs.2.00lacs.CurrentSituation:

InthepapermachineNo.7fourvacuumpumps（allKVM600）arerunningcontinuouslyandhavingcommonheaderforCouch,suctionpress,flatboxes&uhlebox.RequirementofsuctionvacuuminCouchandsuctionpressishighi.e.upto400mmHgandinFlatBoxanduhleBox,itislessi.e.200mmHg.Allthefourpumpsareconsumingabout273kWhpower.Suggestion&Potential:

AstherequirementofsuctionvacuumislessincaseofFlatBoxesanduhleboxitisrecommendedtofabricateseparatelinesfortwovacuumpumpsandreducetherpm500frompresent550rpm.Asavingpotentialof14kWhisestimatedagainstreductionofrpmresultinginsavingofRs.2.7lacswithaninvestmentofRs.50,000.ImprovementEffect（A）:

Rs.32.96lacs/annumInvestment（B）:

Rs.13.50lacsSimplePayBack（B/A）:

5monthsENERGYEFFICIENTFORMERSTwinwireformingisnewprinciplehadtheadvantagesofavoidingthefreesurfacebetweenmixandair,ofincreasingthedewateringcapacitybyallowingdewateringcapacitythroughtwowires.TheformingsectionsisveryshortandtheformationtakesplaceinafractionofthetimeittakesforaFourdriniermachine.Producesapaperofequalanduniformqualityatahigherrateofspeed.Couplingtheformerwithapresssectionrebuildoranimprovementinthedryingcapacityincreasesproductioncapacitybyasmuchas30%.Energysavingscomefromreducedelectricityconsumption.Thetechnologyalsomayimprovequalityandelectricitysavingsof41kWh/tofpaper.HIGHCONSISTANCYFORMINGInhighconsistencyforming,thefurnish（processpulp）whichentersattheformingstagehasmorethandoubletheconsistency（3%）thannormalfurnish.Thismeasureincreasesformingspeed,andreducesdewateringandvacuumpowerrequirements.Electricitysavingsareestimatedat8%thatisabout41kWh/tofpaper.PRESSINGSECTIONPRESSINGARRANGEMENTSDryingthesheetofpaperusingsteamheateddryersisalotmoreexpensivethanusingefficientpresses.Theprimaryfunctionofthepresssectionthereforeistoremoveasmuchwaterfromthesheetaspossible,consolidatethesheetandimprovethesurfacesmoothness.EXTENDEDNIPPRESS（SHOEPRESS）Theadditionalpressingareaallowsforgreaterwaterextraction,（about5-7%morewaterremoval）toalevelof35-50%dryness.Thistechnologyreducestheloadonthedryer,itallowsplantstoincreasecapacityupto25%incaseswheretheplantwasdryerlimited.Extendednippressingalsoincreaseswettensilestrength.HOTPRESSINGPre-heatingthewaterinthepapersheetbeforepressingcanreducetheevaporationload.Useofsteamshowershasbeenestimatedtoreducethesteamrequirementby1kgofsteamperkgpaper.Weestimatesteamenergysavingsof0.61GJ/tpaperthroughhotpressing.CaseStudiesInstallationofSteamBoxesinthePressSectionsCurrentSituationTherearenosteamboxesinstalledinthepresssectionSuggestionWiththeInstallationofsteamboxesthefollowingoptimizationsarepossible:

IncreaseofproductioncapacityorreductionofsteamconsumptioninthedryersectionImprovemoistureprofileIngeneralthedesigndataofsteamboxesareSteamconsumptionapprox.80-120kgsteam/tonnepaper（thevaluedependsonthedrynessofthepaper）Potentialofwarmingupthepaperwebfrom10to15K10Kincreaseofpaperwebtemperaturecorrespondswithanincreaseofdrynessafterthepresssectionofabout1%1%increaseofdrynessafterpresssectionleadsto5%higherproductionor5%less