国际上水泥生产能耗的最佳实践值

国际上水泥生产能耗的最佳实践值InternationalbestpracticevaluesofenergyconsumptionforcementproductionFortheinternationalbestpracticesateachstageofproduction,dataweregatheredfrompublicliteraturesources,plants,andvendorsofequipment.Thesedataandcalculationsaredescribedbelow.各个生产过程的国际最佳实践值是根据公开发表的各种文献资料，以及水泥企业和设备供应商提供的数据确定的。下面来介绍这些数据及其计算过程。Rawmaterialsandfuelpreparation生料和燃料制备Energyusedinpreparingtherawmaterialconsistsofpreblending(prehomogenizationandproportioning),crushing,grindinganddrying(ifnecessary)therawmealwhichismostlylimestone.Allmaterialsarethenhomogenizedbeforeenteringthekiln.Solidfuelsinputtothekilnmustalsobecrushed,ground,anddried.Bestpracticeforrawmaterialspreparationisbasedontheuseofalongitudinalpreblendingstorewitheitherbridgescraperorbucketwheelreclaimeroracircularpreblendingstorewithbridgescraperreclaimerforpreblending(prehomogenizationandproportioning)at0.5kWh/trawmeal,agyratorycrusherat0.38kWh/trawmeal,anintegratedverticalrollermillsystemwithfourgrindingrollersandahigh-efficiencyseparatorat11.45kWh/trawmealforgrinding,andagravity(multi-outletsilo)drysystemat0.10kWh/trawmealforhomogenization.Basedontheabovevalues,theoverallbestpracticevalueforrawmaterialspreparationis12.05kWh/trawmaterial.Ideallythisvalueshouldtakeintoaccountthedifferencesinmoisturecontentoftherawmaterialsaswellasthehardnessofthelimestone.Highermoisturecontentrequiresmoreenergyfordryingandharderlimestonerequiresmorecrushingandgrindingenergy.Ifdryingisrequired,bestpracticeistoinstallapreheatertodrytherawmaterials,whichdecreasestheefficiencyofthekiln.ForBESTCement,itisassumedthatpre-heatingofwetrawmaterialsisnegligibleanddoesnotdecreasetheefficiencyofthekiln.生料制备的能耗包括生料（主要是石灰石）的预混合（预均化和配料）、破碎、粉磨和烘干（如果需要的话）。所有物料在入窑之前都要经过充分的均化。入窑的固体燃料也要先经过破碎、粉磨和烘干。生料制备的最佳实践值计算依据如下：预混合采用带桥式刮板式取料机或斗轮式取料机的纵向预均化堆场，或者带桥式刮板式取料机的环形预均化堆场（电耗0.5kWh/t生料）；破碎采用转子破碎机（电耗0.38kWh/t生料）；生料粉磨采用带高效选粉机和四个辊子的立磨系统（电耗11.45kWh/t生料）；均化采用重力式（多出口筒仓）烘干系统（电耗0.10kWh/t生料）。综合以上能耗数值，生料制备的最佳总能耗为12.05kWh/t生料。理论上，该能耗值还应考虑生料水分和石灰石硬度的影响。水分越大则烘干能耗越多，石灰石硬度越高则破碎和粉磨能耗越多。如果原料需要烘干，则最佳的措施是安装一个预热器，虽然它会降低窑的热效率。“BESTCement”假设烘干湿原料的能耗可以忽略不计，因此没有降低窑系统的热效率。Solidfuelpreparationalsodependsonthemoisturecontentofthefuel.Itisassumedthatonlycoalneedstobedriedandgroundandthattheenergyrequiredfordryingorgrindingofothermaterialsisinsignificantorunnecessary.Bestpracticeistousethewasteheatfromthekilnsystem,forexample,theclinkercooler(ifavailable)todrythecoal.BestpracticeusinganMPSverticalrollermillis10-36kWh/tanthracite,6-12kWh/tpitcoal,8-19kWh/tlignite,and7-17kWh/tpetcokeorusingabowlmillis10-18kWh/tproduct.Basedontheabove,itisassumedthatbestpracticeforsolidfuelpreparationis10kWh/tproduct.固体燃料制备的能耗也与燃料的水分有关。“BESTCement”假设只有煤需要烘干和粉磨，其他物料的烘干和粉磨能耗可忽略不计。烘干煤粉的最佳措施是利用窑系统（如熟料冷却机）的废热做烘干热源。煤粉磨的最佳措施是采用MPS立磨（电耗为10-36kWh/t无烟煤，6-12kWh/t烟煤，8-19kWh/t褐煤，7-17kWh/t石油焦），或碗磨（电耗为10-18kWh/t产品）。综合以上能耗数值，燃料制备的最佳总能耗为10kWh/t产品。--Additivespreparation混合材制备Inadditiontoclinker,someplantsuseadditivesinthefinalcementproduct.Whilethisreducesthemostenergyintensivestageofproduction(clinkermaking),aswellasthecarbonationprocesswhichproducesadditionalCO2asaproductofthereaction,someadditivesrequireadditionalelectricityforblendingandgrinding(suchasflyash,slagsandpozzolans)and/oradditionalfuelfordrying(suchasblastfurnaceandotherslags).除了熟料以外，一些水泥企业还在水泥终产品中添加混合材。该措施在减少熟料生产能耗以及CO2排放量的同时，需要增加混合材的混合与粉磨电耗（如粉煤灰、矿渣和火山灰）以及烘干用的燃料消耗（如高炉矿渣和其他矿渣）。AdditionalrequirementsfromuseofadditivesarebasedonthedifferencesbetweenblendingandgrindingPortlandcement(5%additives)andothertypesofcement(upto65%additives).PortlandCementtypicallyrequiresabout55kWh/tforclinkergrinding,whileflyashcement(with25%flyash)typicallyrequires60kWh/tandblastfurnaceslagcement(with65%slag)80kWh/t(thesearetypicalgrindingnumbersonlyusedtodeterminetheadditionalgrindingenergyrequiredbyadditives,notbestpractice;forbestpracticerefertodatabelowincementgrindingsection).Itisassumedthatonlyflyash,blastfurnaceandotherslagsandnaturalpozzolansneedadditionalenergy.Basedonthedataabove,flyashwillrequireanadditional20kWh/tofflyashandslagswillrequireanadditional38kWh/tofslag.Itisassumedthatnaturalpozzolanshaverequirementssimilartoflyash.Thesedataareusedtocalculatecementgrindingrequirements.Foradditiveswhicharedried,bestpracticerequires0.75GJ/t(26kgce/t)ofadditive.Generally,onlyblastfurnaceandotherslagsaredried.Thoseadditivesthatneedtobedried(thedefaultisallslags,althoughtheusercanenterthisdataaswellintheproductioninputsheet)bestpracticerequiresanadditional0.75GJ/t(26kgce/t)ofadditive.根据硅酸盐水泥（5％混合材）和其他类型水泥（混合材配比最高达65％）在混合和粉磨方面的差别，添加混合材会增加额外的电耗。硅酸盐水泥的熟料粉磨电耗一般为55kWh/t，而粉煤灰水泥（含25％粉煤灰）的粉磨电耗一般为60kWh/t，高炉矿渣水泥（含65％矿渣）的粉磨电耗一般为80kWh/t（这些能耗数值是掺加混合材的一般能耗水平，不是最佳能耗水平；最佳能耗水平可参考下文的水泥粉磨部分）。“BESTCement”假设只有粉煤灰、高炉矿渣、其它矿渣和天然火山灰需要额外的能耗。综合以上能耗数值可知，粉煤灰需要的额外电耗为20kWh/t粉煤灰，矿渣需要的额外电耗为38kWh/t矿渣。天然火山灰的额外电耗假设与粉煤灰相同。这些数据可用于计算水泥粉磨电耗。混合材烘干热耗的最佳水平是0.75GJ/t（26kgce/t）混合材。一般情况下，只有高炉矿渣和其他矿渣需要烘干。那些需要烘干的混合材（默认情况是所有矿渣，虽然用户可以在生产信息输入表中输入该数据）的最佳烘干热耗为0.75GJ/t（26kgce/t）混合材。--KilnClinkerproductioncanbesplitintotheelectricityrequiredtorunthemachinery,includingthefans,thekilndr