REYMA MATERIALES REFRACTARIOS Technical Department High-Efficiency Refractory Linings to reduce the impact from Cement plants on Greenhouse Gases emissions through fuels savings 1/10 High-Efficiency Refractory Linings to reduce the impact of Cement plants on Greenhouse Gases emissions through fuels savings SUMMARY 2 CONTEXT OF CLIMATE CHANGE 2 GREENHOUSE GASES EMISSIONS (GHG) IN CEMENT INDUSTRY 4 HIGH-EFFICIENCY REFRACTORY LININGS (HERL) FOR REDUCTION OF GHG EMISSIONS 6 CONCLUSION 10
SUMMARYCement Industry has a very relevant impact on Greenhouse Gases emissions (GHG) at globallevel, causing the everydaymore obvious Climate Change leading to environmental incidents,affecting our planet and ourselves. The industry is implementing practices aimed to thereductionofemissions,beingoneofthemaininitiativesthereductionoffossil(coals)orderivedfrom fossil (petcoke) fuels burned for clinker production, intermediate product for cementmanufacture.RefractoryliningsatclinkerkilnshavethereforeapotentialofbeneficialimpactonthereductionofGHGemissionscausingGlobalWarming, throughtheadoptionofHigh-EfficiencyRefractoryLinings (HERL),minimising theconsumptionof fossil fuelsnecessary forclinker fabricationandhence reducingbothGHGemissionsandvariableproductioncosts.HERL investment isquicklypaid off thanks to thermal savings, while strategically becomes mandatory in the context ofClimateEmergencywelivein.
CLIMATECHANGECONTEXTCurrentlythegraveproblemofClimateChangehasbeenrenamedasClimateEmergencygiventheevidenceofquickglobalwarmingoftheEarthandthemagnitudeofitseffectsonthenaturalhabitatsandpopulatedareas, takingplacemuchmoreoftenextremephenomena likemassivefires,prolongeddroughts,icebergsmelting,floodscausedbythelossofforestmass,etc.It is commonly accepted by the Scientific Community that within this 2020-2030 decadeHumanity must adopt urgent policies and put in place measures aimed to the sustainedreductionofGreenhouseGases(GHG),maincauseoftheglobalwarming.Inthiscontext,thePowerGenerationsectorfromfossilfuelsappearsasthemajorcontributor,followed by a series of industrial processes headed by Cement Industry. Cement productioncontributeswithuntil8%ofglobalGHGemissionscausedbyhumanactivity,morethanalltheworldwide road trucks fleet used for terrestrial transport. Moreover, Cement sector is thesecond global generator of CO2 and third global energy consumer, which in turn requires ahigherutilisationofpollutantpowerstations.
Source:USEnvironmentalProtectionAgencyCO2emitted forcivilworksconcretemanufacture (fromwhich14% iscement) isestimatedas410kgCO2/m3ofconcrete,inotherwords,some180kgforeachtonofconcrete(atanaveragedensity of 2.3mT/m3), although the use of fly andwet ashes (more andmore scarce due togradualparalisationof fossil fuelspower stations)may reduce theseemissionsbyuntil a30%.CO2emissions due to civilworks concrete fabrication is thereforedirectly proportional to thecementcontent inconcrete.900kgofCO2areemittedforthefabricationof1tonofcement,assuminganaverageof70%ofemissionsrelatedtoeachtonofconcrete.Therefore it is urgent the adoption of immediatemeasures to revert this trend, whichmajorCementGroupsworldwidearearticulatingaround:
replacingclinkerandcompatiblewithcementspecifications.• Electric power co-generation for internal consumption of cement plant, usually from
sparehotairfromcoolers,hencereducingthedemandofelectricpowerfromthegrid.• Development and production of new clinker types, of lower environmental impact
It should be remarked that these measures are subject to technical and process limitations,conditioning their effectiveness, butmuchmore can still be donewithin the scope of energyoptimisation.GREENHOUSEGASESEMISSIONS(GHG)INCEMENTINDUSTRYInternationallygasesconsideredasGreenhouse(GHG)arewatervapour (H2O),carbondioxide(CO2),nitrogenoxide(N2O),methane(CH4)andozone(O3).Amongthem,fromEuropeanUniondata,81%ofemissionsareduetoCO2,11%tomethaneand5%toN2O.Therefore,CO2controlmeasureswillleadtoaquickereffect.Watervapourjoinswatercycleandthereforeisnaturallyabsorbed.IntheclinkerproductionprocessforcementmanufactureamassivevolumeofCO2isgeneratedfromtwosources:
• Thermal emissions : fuels combustion (40% emissions related to burning process).Hydrocarbonfuelsgenerate,attheexothermicreactionstakingplaceduringcombustion,heat,CO2andwatervapour.InordertoreduceCO2emissions,itismandatorytoreducethe volume of necessary fuel per ton of clinker. The amount of hydrocarbon fuelnecessaryisdefinedbytheamountofavailablewastefuelsburned(residualwastes,notfossil orderived from fossil), and theamountofnecessaryheat toproduceone tonofclinker.
HYDROCARBONFUEL+O2èHEAT+CO2+H2OHarder rawmeals (less suitable to cooking)will needahigherCombustion (Formation)Heat and thereforewill imply a higher Specific Heat Consumption (SHC) at the clinkerproductionline.
• Process Emissions : decarbonation of raw materials (>50% emissions, associated andinseparablefromrawmaterials),thermaldecompositionofcarbonatestoreleasecalciumoxide(lime)whichwilllaterbecombinedtoformclinkercompounds.ThisdecarbonationreactionreleaseshighvolumesofCO2totheatmosphere.Unfortunatelytheseemissionsareintrinsictotheproductionprocessandcanonlybereducedbydecreasingtheclinkervolumes produced. As a consequence, Cement plants are trying to reduce theclinker/cementratio,whichinturnalsoleadstoenergysavings,ordevelopnewtypesofmorereactiveclinkerswhosecontributiontocementislowerinpercentage.
Therefore,Cementplantsaremakingspecialeffortstomaximisetheburningofavailablewastefuels,despitetheprocessandoperationalstabilityproblemsconnectedtothem,aswellastryingto reduce the Specific Heat Consumption (SHC, amount of total heat consumed per ton ofclinker).Within this latter group of control measures is where refractory linings play a vital role tocontribute to the reductionof emissions, through thedecreaseof fossil fuels usage (petcokesandcoals).
HIGH-EFFICIENCYREFRACTORYLININGS(HERL)FORREDUCTIONOFGREENHOUSEGASES(GHG)EMISSIONSTraditionallyCementplantshavepaidmuchattentiontotheselectionofrefractoryliningswithrobust hot-face materials in order to cope with process conditions and perform for longlifetimes.Insulationlayershaveusuallyreceivedlessconsideration,seenassomethingnecessarytoreduceheatloss,inmanycaseswithoutconcedingtoomuchimportancetothem.With the gradual introduction of waste fuels, chemical conditions of combustion gases andcomposition of material build-ups formed over the linings, specially connected to the use ofhighersulphur,cheaperpetcokes,havefavouredtheappearanceofacidcorrosionphenomenaon steel casings, inparticular at theareasof injectionofwaste fuels inpreheaters, aswell ascondensationareas(inletchambers)ofthegasesgeneratedatthemainburner.Traditional liningsweredesignedwithconventional insulatingmaterials, like lightweightbricks,calcium-silicate boards and insulating concretes of several capabilities and densities, offeringthermalconductivitiesacceptabletodate.However,undertheClimateEmergencyproblemandhigherneedofplantstoadjustfuelsvariablecosts,itmakesmoresensethanevertoreviewthelinings specifications to minimise fuels consumption, while enhancing their performance andresistanceagainstprocessdemand.It is important to remark that heat losses in linings happen due to the three ways of heattransmission:conduction,convectionandradiation.Theevaluationoftheselossescanbesimplyestimated through the use of thermal cameras and later calculation of losses (kWh orkilocalories)pereachkiln component (cyclone, smokeschamber, calciner,ducts,etc.).RegularinspectionsandthermographicreportsareacrucialtoolforplantsProcessteamstocontroltheenergy consumption at any given time and therefore emissions to atmosphere, aswell as forplanningofrefractorymaintenanceshutdowns.Thermal bridges, mainly metallic elements inserted in the lining like steel anchors, consoles,beams,mandoors frames, steel stiffeners, air blasters nozzles, Cardox pipes, samples/tappingpoints,processprobes,etc.,aswellasthenecessaryexpansionjointsfortherefractorylinings,arealldetrimentalforthethermalefficiencyastheyincreaseconductivityandheatlosses,andmustthereforebetakenintoaccountwhendesigningtheoptimumlining.
Inviewofthecomplexthermomechanicaldemandandchemicalattackoverthehotface,aswellas the higher need of insulation, REYMA has developed High-Efficiency Refractory Linings(HERL),allowingtheplanttooptfor:OPTION1–High-Efficiencyrefractoryliningswithlongestlifetime:Thissolutionallowsplantstoobtainallthebenefitsfromahigh-performancelining,extendingitslifetime to themaximumpossiblekeeping thecurrent total thickness, inotherwords, keepingcurrentkilnthroughput(tonsperday):
• Keeping current total thickness, maximising hot-face thickness while minimisinginsulationthickness.
• Usingstate-of-the-artdensematerialstoextendlifetimestothemaximum.• Combination of application techniques of dense materials depending on areas and
requirements, choosing between vibrocasting or high-pressure gunning, hydraulic orceramicbonding,aswellashigh-performancepre-castblocks.
OPTION2–High-Efficiencyrefractoryliningswithmaximumsavingspertonofclinker:This solution allows the plant to increase kiln throughput (tons per day), particularly whenappliedatbottleneckareas,asitreducesthetotalliningthickness,droppingthereforepreheaterdifferentialpressure(deltaP)andincreasingoxygenavailableforcombustionforthesamelevelofdraft(mainIDfan).ThehigheramountofO2availableallowstoincreasekilnoutput(feedandfuels),henceincreasingkilnperformanceandreducing,asaddedvalue,specificpower(electric)consumption (per ton of clinker) due to the dilution of the power consumption of the fixedconsumers(maindrives)overahigherhourlyoutput:
• Keeping the current thickness of hot-face, review and upgrade the specification of thedensematerialtoextendlifetime,applyingcostoptimisationcriteria.
• Combination of application techniques of dense materials depending on areas andrequirements, choosing between vibrocasting or high-pressure gunning, hydraulic orceramicbonding,aswellashigh-performancepre-castblocks.
HERLselectioncriteriaandREYMAtechnicalservicePlant priorities and cost-benefit criteria will allow to select one option or another, or acombination of both, to optimise energy consumption, reduce emissions and maximise kilnthroughput.REYMA offers all our customers the following materials and services to optimise EnergyEfficiencyoftheirlinings:
• Process studies from customer plant information over the existing lining, current andfuturedemand,inordertoproposeHERLoptimumspecifications.
face layers to guarantee the maximum performance and lifetimes. Variety of denseproducts include vibrocast or high-pressure gunning versions with our exclusiveGUNTIX®-HPtechnology.
• Supply of super-insulating materials, based on the latest technology in insulationsystems, in order tominimise heat loss, available in a variety ofmaterials, shapes andprotectionsagainstmoistureandcorrosion.
CONCLUSIONCement Industry iscurrently livingacontextofstrong increaseofoverallproduction,expectedby 2030 around 5,000millionmetric tonnes, up until 4 times 1990 volumes. Simultaneously,ClimateEmergencysituationrequirestheadoptionofurgentandsignificantmeasuresaimedtothe reduction of fossil fuels consumption by plants. And finally, the higher and highercompetitivityonworldwideclinkerandcementmarketsandpricesisputtingahardpressureonCement groups and factories, forcing them to implement measures to reduce costs, oftencompromising the reliable run of equipments, particularly those units using medium-qualityrefractorylinings.High-Efficiency Refractory Linings (HERL) designed and suppliedbyREYMAoffer a solution tothese problems, contributing to thermal savings, improvement of equipments reliability andreductions of GHG emissions. Strategically, plants installing these new linings enjoy from acompetitiveandtechnlogicaladvantageagainstcompetition.REYMA is as always at disposal of all current and future customers for the study andimplementationoftheselinings.
