State Key Laboratory of Coal Combustion,School of Energy and Power Engineering,Huazhong Universityof Science and Technology

我国钢铁行业以高炉-转炉长流程为主,一次能源消耗主要为煤粉与焦炭,化石能源消耗大、碳排放高,其中70%的CO2排放集中在高炉炼铁工序。双碳背景下,亟需研发低碳炼铁技术以降低高炉工艺的能源消耗和CO2排放。提出一种生物质重整煤气喷吹-氧气高炉(BRGI-OBF)工艺流程,该工艺通过优化气化炉工艺参数与生物质替代煤粉重整,产生的重整煤气满足高炉的富氢冶炼需求,并降低了化石能源的使用。结合高炉煤气富氧燃烧碳捕集,可实现末流烟气中CO2富集,从而实现高炉低能耗与低碳(负碳)排放。为分析BRGI-OBF工艺的低碳潜力,首先运用AspenPlus搭建了BRGI-OBF工艺模型,研究了气化炉输入热量与生物质种类对工艺性能的影响。基于计算得到的工艺参数,运用高炉炼铁工艺能耗计算方法,对比分析了传统高炉工艺与炉顶煤气循环-氧气高炉(TGR-OBF)工艺的能耗与碳流情况。结果表明,向气化炉提供适宜的热量可有效减少煤粉用量,同时增加循环煤气量,最多可减少煤粉用量124.2kg/t(以生铁计);生物质种类对生物质用量与重整煤气的组分产生显著影响,采用杨木半焦进行重整时,杨木半焦用量为204kg/t,重整煤气中H2体积分数达29.91%,满足富氢冶炼需求。此外,BRGI-OBF工艺显著改善了能源结构,其化石能源占比约55%,与传统高炉相比,降低煤粉消耗17.6%、焦炭消耗29.3%。该工艺流程耦合富氧燃烧碳捕集技术后,末流中存在碳素372.6kg/t,以易于压缩捕集的高浓度CO2(>90%)形式存在。扣除由杨木半焦造成的碳素排放,总碳素排放为-109.9kg/t,相当于生产每吨铁水可额外捕集CO2403kg,可实现生物质+CCS的负碳技术,为钢铁行业实现深度脱碳提供重要支持。

China′s iron and steel industry is dominated by the long blast furnace - converter process, with primary energy consumption mainly pulverized coal and coke. The large amount of fossil energy consumption leads to high carbon emissions, 70% of whichare generated by the blast furnace ironmaking process. To realize the " Dual Carbon" targets earlier, it′s urgent to develop low-carbonironmaking technologies to reduce the energy consumption and CO emissions from the blast furnace process. In this study, a biomass reformed gas injection-Oxygen Blast Furnace (BRGI-OBF) process was proposed. In this process, the gasifier process parameters were optimized, and biomass reforming was adopted instead of pulverized coal reforming. Thus, the reformed gas meets the blast furnace′s hydrogen-rich smelting demand and reduces fossil fuel consumption. Combined with carbon capture in the oxygen-enriched combustion of blastfurnace gas, CO in the end-stream flue gas can be greatly enriched, thus realizing low energy consumption and low carbon (negative carbon) emission of the blast furnace. In order to analyze the low-carbon potential of the BRGI-OBF process, a model of the BRGI-OBFprocess was first constructed by the chemical process analysis software Aspen Plus. Then, the effects of the heat input to the gasifier andthe type of biomass on the process performance were analyzed. Furthermore, based on the calculated process parameters, the traditionalblast furnace process and the top gas recycle-oxygen blast furnace (TGR-OBF) process were horizontally compared in terms of energy consumption and carbon flow by applying the energy consumption calculation method of the blast furnace ironmaking process. The results show that supplying appropriate heat to the gasifier effectively reduces pulverized coal consumption by up to 124.2 kg/ t(per metricton of hot metal) and increases the amount of recycled gas. Notably, different biomass types have a significant effect on the amount of biomass and the composition of reformed gas. When poplar semi-coke is used for reforming, 204 kg/ t of poplar semi-coke would be consumed with up to 29.91% of H in the reformed gas, fulfilling the needs of hydrogen-rich smelting. In addition, the BRGI-OBF processsignificantly improves the energy structure with a fossil energy share of about 55%, reducing the consumption of pulverized coal and cokeby 17.6% and 29.3%, respectively, compared to conventional blast furnaces. With the process coupled to oxygen-enriched combustion carbon capture technology, 372.6 kg/ t of carbon exists in the end stream in the form of highly concentrated CO(>90%) that can beeasily compressed and captured. Deducting the carbon emission from poplar semi-coke, the total carbon emission would be -109.9 kg/ t,which is equivalent to 403 kg of additional CO capture per ton of iron produced. This process can realize the carbon negative technology ofbiomass + CCS, which significantly support the iron and steel industry to achieve deep decarbonization.

国家重点研发计划资助项目(2021YFF0601000)

毛文超,黄志辉,张泽武,等.生物质重整煤气喷吹-氧气高炉的低碳潜力分析[J].洁净煤技术,2024,30(8):138-149.

MAO Wenchao,HUANG Zhihui,ZHANG Zewu,et al.Analysis of low carbon potential of biomass reforming gas injection-oxygen blast furnaces[J].Clean Coal Technology,2024,30(8):138-149.