面向长流程的富氢低碳炼铁技术路径分析

Technical pathway analysis for low-carbon ironmaking with hydrogen-rich towards long-process

高炉→转炉长流程是中国钢铁生产的主要流程。在“双碳”背景下,绿色低碳发展成为钢铁行业转型发展的核心命题,目前国内外主要采用以氢代碳的氢冶金低碳技术路线,国内路线以富氧高炉和氢基竖炉为主,推动着传统高炉向富氢全氧碳循环技术进行转变。结合氢冶金机理和现有的典型低碳工艺技术路线特点,分析了氢冶金技术路线的减排上限问题,从限制传统高炉减排的关键参数入手,提出了一种全氧富氢低碳还原熔化炉炼铁系统和炼铁方法。炼铁系统包括还原熔化炉、煤气除尘器、干燥器、CO_(2)分离器、电解水装置、风机、换热器、还原气备用储气罐、烟囱等设备,其中还原熔化炉自上而下依次包括间接还原区、软熔滴落区、焦炭燃烧及渣铁区;炼铁方法包括矿焦混装、间接还原区喷入由电解产生的绿氢与炉顶循环煤气组成的混合还原气、焦炭燃烧区鼓入纯氧、炉顶煤气CO_(2)回收、渣铁处理。通过设计新炉型和优化参数,使间接还原区金属化率达到85%~95%,大大降低吨铁冶炼碳耗。基于热力学理论计算、相关的物理试验数据和6种典型工艺流程的CO_(2)排放指标分析等研究成果,进一步阐述了新工艺的可行性及推广前景,新工艺采用全氧使自身反应器还原产生的煤气得以循环利用,达到CO_(2)排放降低50%以上的目标,实现绿色低碳冶金。

The long ironmaking process with blast furnace and basic oxygen furnace(BF→BOF)is the leading process of steel production in China.Under the background of"dual carbon",green and low-carbon development has become the core proposition of the transformation and development for the iron and steel industry.At present,the hydrogen metallurgy low-carbon technology route based on hydrogen instead of carbon is mainly adopted at home and abroad,and the domestic route is mainly oxygen-rich BF and hydrogen-based shaft furnace(SF).It promotes the transformation of traditional BF to hydrogen-rich and oxygen and carbon-recycle(Hy-O-CR)technology.Combined with the mechanism of hydrogen metallurgy and the characteristics of the existing typical low-carbon process route,the upper limit of CO_(2)emission reduction of hydrogen metallurgy technology route is analyzed.Starting with limiting the key parameters of CO_(2)emission reduction in BF,the author puts forward a new ironmaking system and method of reduction smelting furnace(RSF)with Hy-O-CR.The ironmaking system includes many sets of equipment such as reduction smelting furnace,gas dust collector,dryer,CO_(2)separator,electrolytic water device,blower,heat exchanger,storage tank of reduction gas,chimney,and other equipment,in which the reduction melting furnace includes an indirect reduction zone,a soft melting dripping zone,and a coke combustion zone from top to bottom.Ironmaking methods include coke and ore mixed charging,injection of the mixed reduction gas composed by electrolytic green hydrogen and circulating gas from the furnace top gas in the indirect reduction zone,injection of oxygen in the coke combustion zone,CO_(2)recovery of the furnace top gas,slag and hot metal treatment.By designing the size of new furnace type and optimizing parameters,the metallization rate of ore in the indirect reduction zone is up to 85%-95%,and the carbon consumption per ton of hot metal is greatly reduced.Based on the theoretical calculation of thermodynamics,the relevant physical experimental data and the analysis of CO_(2)emission indexes of six typical processes,the feasibility and popularization prospect of the new process are further expounded.Using the full-oxygen method to recycle the reduction gas produced by its own reactor,the process achieves the goal of reducing CO_(2)emissions by more than 50%,and realizes green and low-carbon metallurgy.