炼铁系统的C〇2排放|1|钢铁流程总排放的70%w±,降低炼铁系统的碳 耗对于减少钢铁.1:业C〇2排放.11带蓝耍。商炉炼铁系统巧过近凡十年的技术 发展,运行效率己经人大捉高,要想进步辟化炼铁过程的C〇2排放,需发 展新的低碳炼铁工艺。炉顶煤气循环氧气島炉炼铁技术采用氧气代替热空气 鼓风,大量喷吹煤粉,炉顶煤气经脱除C〇2后喷吹进高炉循环利用,具有高 生产率、高喷煤量、低焦比和低碳排放等优点。本文从基础工艺、关键过程 和钢铁流程等不同摆次建立模型来分析氧气高炉工艺可行性,获得7关键技 术参数影响规律,解析了炉内热化学行为,评估I钢铁流程的能耗和碳排放。 本文建立的氧气高炉系统」:艺模型包含炉身炉腹区传输与反应模型、风 口回旋区燃烧模型liJ■及炉外煤气能质平衡横型。该了艺模型实现TH个子模 型的稱合计算,可W更精准地描述炉内热化学过程煤气分配情况。利用该模 型,研巧了莱钢3号高炉的改造方案和氧气高炉系统关键技术参数的影响规 律。研究表明:为了保证炉内合理的理论燃烧温度和较好的铁矿石还原效果, 风曰循环煤气的流量应为300Nm-Vt-铁左右,鼓风氧气浓度不低于80%,上 部炉身循环煤气流量不低于300Nm'Vt-铁:鼓风氧气浓度为炉内直接还原度 和炉顶煤气热值的主要影响因素,而循环煤气流量为煤气外供量和工序能耗 的主耍影响因素;与传统高炉相比,氧气高炉的气体还原性更强,炉内直接 还原反应更少,综合能耗和C化净排放可分别降低6.4%和35.7%。 针对氧气高炉艺带来的炉内关键过程变化,本义通过实验和数值模拟 来分析工艺参数设定的合理性。通过兰维半周高炉模型实验,研究7炉料T 降行为,结果表明:料流K降平推流为主,氧气高炉带来的气流减少和生 产率提高对炉料K降化为影响化小,HUM旋区尺寸变化对炉腹区域汇聚流 巧巧影响。通过风n时旋K苗!模巧来分析巧粉燃烧行为,结果表明:氧 气含量:提高可有效提巧煤粉燃烧效巧:氧气高炉工况F的回旋区尺寸减小, 而煤粉喷吹璧义期塑巧大幅提商,这些都对煤粉的燃烧小利,需通过喷吹循 环煤气和适当的炉型改造乂扩乂回旋区,保证煤粉的燃烧效果。通过全炉传 输与反应过程二维模型,研巧煤气循环的影响,结果表明:与传统高炉相比, 氧气高炉的气流较小,软融带更薄;提离炉身煤气喷吹戰,可提升气固温度 及软融带位置,增强炉内气氛还巧性,加快铁氧化物还原速度。但循环煤气 喷吹量需控制在合理范閱来避免炉顶煤气温度过高,造成炉顶设备无法正常 运行,并因高温煤气排出损失大蘆热能。 -III- 巧于《店次模消的炉顶煤气循环氧气岛炉uf巧性研究 结合实际钢厂生产运行数据,建立钢铁流程的物质流、能量流模型,来 评估氧气高炉钢铁流程的能耗和碳排放。氧气嵩炉应用后,钢铁流程煤消耗 量减少26.]%,制氧需求量提高1.7倍,电九消耗量提高50.9%,副产煤气总 产量降低53.4%,在钢/ ' 副产煤气供需平衡的甚础.L,氧H高炉钢铁流程可 实现煤气零放散。氧气高炉钢铁流程的综合能耗受电人折标系数影响较大。 随着我国发电效率提島和火电比例降低.化等价侦会不断减小,氧气高炉 钢铁流程的节能潜力会随之增大。若捕集的C〇2不封备,氧气高炉钢铁流程 的C〇2直接排放可比传统流程降低26.2%;若捕集的C〇2‘把现封存,0)2直 接排放和净排放可比传统流程分别降低56.5%和40.9%。 炉顶煤气循环氧气高炉是新颖,并存在争议的低碳炼铁技术。希望本文 的方法和结果能够为我固该技术的发展提供帮助,并为该技术的理论基础和 工程应用提供指导。 关键词:氧气高炉,煤气循环,数学模型,可行性,碳排放 -IV- 北点科技大巧辟I:‘’声位论义 Feas化ilityInvestigationonOxygenBlastFurnacewithTop GasRecyclingBasedonMulti-levelModels Abstract Itisvei＊yimportant阳lowerC〇2emissionof化eiron-makingprocesswhich emitsover70〇/〇ofC〇2thewhole^ronandsteelmanufactiuingsys化m.After severaldecadesofdevelopment,化ereisnomuchpotentialforcarbonemission reducdo打intheprocessofconventionalbiastfurnace(BF),soitiscertainlyurgent todevelopnewlow-carbontechnologiesforiron-makingprocess.The打ewprocess ofoxyge打blastfurnacewkhtopgasrecyciing(下G民-OBF)usesroom-tempei＊ature oxygenratherthanhotairintheconventionalprocess,withthetopgasre-injected throughthemai打a打dstacktuyeresafterdecarbonizingandheating.Asaresult,the TGR-OBFprocessisthoughtwithadvantagesofhighproductivity,highpulverized coalinjectionra化,lowcoke巧tioa打dlowcarbonemission,anywayitissdnargued inbothfundameMalandengineering.Theobjectiveofthis出ssenationisto i打vestigatethefeasibilityofTG民-OBFprocessbasedonmodelsfromfurnacelevel, systemlevel化iron-steel-makingprocesslevel.Vianunwriccomputationand experimentalvalidation,t;hein-fumacedieiTnochemicalbehaviorswererevealed a打dt;heinfluenceofsomekeyKchnicalpai＊ametersonenergyconsumptionand carbonemissionwereanalyzedtoevaluatethenewprocess.Themain achievementsinclude: Aprocessmodelwas巧rstlydevelopedfbrt:heTGR-OBFsys化m,which consistsofthreesub-models:aone-dimensionalmodelofheattransferand reactionsinthestackandboshzone,anequilibriummodelforcombustionatthe raceway,amassandenergybalancemodelforthedistributionoftopgas.Withthe couplingcalculationofthethreesub-models,theprocessmodelmakesmore accuratepredictionofthethermochemicalprocessandthegasbalancecomparedto theuncoupledmodels.Thentheprocessmodelwasus’edtoinvestigatethe upgradingdesignoftheNo.3BFofLaiwuSteelCo.Ltd.andsomekeyparameters. Toachievethereasonableflametemperatureandthefiillreductionofironore,the oxygenconcentrationshouldbesetover80〇/〇,andthevolumesoftheupperand lowerrecycledgasshouldbesetbothover300NnrVthm(thm-tonofhotinetal). Itwasalsofoundthattheoxygenconcentrationisthedominantfactoronthedirect reductionratioandthecalorificvalueoftopgas.Thevolumeofrecycledgasisthe dominantfactorontheenergyconsumptionandthetopgasoutput-Thecomparison ofperfovmarvcebetweenco\we、、\AovAa\BFand化e了G长-OBFshows化atthe -V- 巧多掉次模叩j的炉顿煤气術环氣气廚炉uj巧性研光 TG民-OBFisavailableforhighergasreducibilityandlesscon化ibution行omdirect reductionreactionsparedwiththeconventionalBFprocess,theTGR-OBF processdecreasestheenergyconsumptionby6.4%andthenetCO2emissionby 35,7%. Furthennore,thekeyparametersinfurnacefortheTGR-OBFprocesswere analyzedbytheexperimentsandnumericalsimulations.Inthispa,thesolid descendingbehaviorswerefirstlyinvestigatedbytheexperimentsofathree- dimensionalsemicirclebench.Theresultsshowedthatthesolidflowisaffectedby thesizeofraceway,butlittleaffect:edbythegasflowandtheburdendescending ra化.Athree-dimensionalmodelwas化endevelopedtoanalyzet:hecombustion behaviorsofthepulverizedcoalattheraceway.Highertheoxygenconcentration andracewaysize,lowerthecoalrate,higherthecombustionefficiencyofthe pulverizedcoal.Toobtainanefficientcombustion,wecouldbuilda打ecessarijy largeracewaybyre-injectingtherecycledgasandmodifyingthefiimacestructure. Atwo-dimensionalmodelbasedonthetransportphenomenaandreactionkinetics wasalsodevelopedtoinvestigatetheeffectofrecycledgas0打theTGR-OBF. ComparedwiththeconventionalBF,theTG民-OBFhassmallergasflowand thinnercohesivezone.As化eamountofdierecycledgas1打〔化3565,化e!:emperature increases,thepositionofcohesivezonegoeshigher,and化egasreduc化ilityand thereductionrateoftheironoreincrease.However,theflowrateoftherecycled gasshouldbeinareasonableran呂etopreve打tdietopgasoverheatingfor equipmentshealthandenergysaving. Finally,awhole-processmodelofmat:enalandenergyflowswasdevelopedto evaluate化eenergyconsumptionandcarbonemissionin化eintegra化dsl;eelmill (ISM)withTGR-OBFtechnologybasedonthepracticalproductiondata. Comparedto化econventionalISM,化ecoalconsumptionoft:heTG民-OBFISM reducesby26.10/0,theoxygenconsumptionincreasesby1.7times,化eelectricity consumptionincreasesby50.9%,andthemetallurgygasgenerationdecreasesby 53.4%.MoreovertheTGR-OBFISMcanrealizezeroemissionofmetallurgygas bykeepingthegasbalance.TheTGR-OBFISMhasgenerallygreatenergysaving potentialsaccountingforthefuturedecreaseoftheenergyequivalentvalueof electricityalongwiththeefficiencyimprovementofpowergeiierati饥1,although化e valueismuchdepe打denton化eselectionofenergyvaluesforelectricitypared witlnheconventionalISM,thedirectCO2emissionfrom化eTG民-OBFISMcould reduceby26.2%withoutCO2captureandstorage(CCS),andthedirectandthenet CO2emissioncouldre加ceby56.5%and40.9%withCCS. The化chnologyofTG民-OBFisciurentlya打ovelandwiddy-arguedconcept iniron-makingprocess.Wehope,andwebelievethattheapproachesandresultsin -VI- 北京科技乂学睛十学位论义 化isdissertationcouldprovidesome化ingmeaningflilin化edevelopmentofthis technologyinChina,inbothfundamentalandengineeringapplications. KeyWords:oxygenblastfurnace,gas化cycling,mathematicalmodel, feasibility,carbonemission -VII- 北诉科技大学階-k学位论义 目录 ItillI 摘要Ill AbstractV 1'JlN1 2文献综述 2 2.1高炉炼铁工艺发展现状 2 2.1.1高炉炼铁节能减排的重耍性 2 2丄2高炉炼