【作者】 冯超；

【导师】 朱荣；

【作者基本信息】 北京科技大学 ， 冶金工程， 2022， 博士

【摘要】 我国钢铁行业的CO2排放量约占全国CO2排放总量的15%,少数钢铁企业开展了工业尾气CO2捕集利用的工程建设,但原料气气源石灰窑和热电厂尾气中的CO2含量普遍小于30%,且石灰窑和热电厂区域距离转炉冶炼区域较远,造成CO2捕集项目的投资运行成本、能耗和占地面积大幅度增加。基于此,本文提出了“转炉炼钢CO-CO2质能转换自循环利用”的新工艺思路,采用转炉煤气富氧燃烧富集烟气中的CO2,降低CO2捕集的投资和运行成本,有助于推动钢铁企业大规模捕集CO2资源化利用技术的发展。分析了助燃气成分、当量比、循环烟气和预热温度对于转炉煤气富氧燃烧特性及烟气性质的影响,确定了当量比为0.9的SCH-3为最适合CO2捕集工序的燃烧方案;经过4次循环的烟气中CO2含量稳定在74.32%,预热温度降低了烟气中NOx的生成量,但对烟气中C02含量没有影响。研究了不同CO2捕集流程的碳排放及（火用）效率,发现C-PRO-1、C-PRO-2、C-PRO-3 和 C-PRO-4 流程的碳排因子分别 为 3.7811 tCO2/km3、3.2057 tCO2/km3、1.8553tCO2/km3 和 0.8701tCO2/km3,产品（火用）效率分别为 9.76%、6.71%、4.34%和 4.51%,而回收（火用）效率分别为 9.76%、6.71%、18.27%和 19.01%。建立了转炉顶底复吹CO2冶炼的物料平衡和能量平衡模型,开展了 CO2冶炼工业试验,确定CO2喷吹最大比例为14.71%,且煤气和蒸汽循环作为捕集工序的输入项不会影响能源平衡;U-BOU-1边界和U-BOU-2边界的CO2排放量分别为165.5 kg/t钢和138.2 kg/t钢,（火用）损失分别为7.17%和5.98%,（火用）效率分别为92.83%和94.02%,主产品（火用）效率分别为84.75%和85.01%。评估了新工艺思路(PRO-4流程)的碳排放、（火用）效率和经济性指标,发现PRO-4流程的CO2排放量为0.1404t/t钢,相比常规冶炼、PRO-1、PRO-2和PRO-3流程的CO2排放量分别减少了 25.13 kgCO2/t钢、16.91 kgC02/t钢、13.57 kgCO2/t 钢和 5.72 kgCO2/t 钢;C-PRO-4 流程的运行成本为 247.64 元/km3CO2,相比 C-PRO-1、C-PRO-2 和 C-PRO-3 流程分别降低了 39.5%、55.5%和 26.3%。本文的研究成果将为“转炉炼钢CO-CO2质能转换自循环利用”新工艺提供参考依据,有助于钢铁企业CO2捕集利用技术的进一步发展。更多还原

【Abstract】 The CO2 emission from iron and steel industry accounts for about 15%of the country’s total CO2 emission in China.Only a few iron and steel enterprises have carried out the projects for industrial exhaust CO2 capture and utilization.One reason for this phenomenon is that the content of industrial exhaust CO2 from feed gas source lime kiln and thermal power plant is generally less than 30%,the other is that the lime kiln and thermal power plant are far away from the converter smelting area,which resulting in a significant increase of the investment and operation cost,energy consumption and land area of CO2 capture projects.Hence,a new process idea named "capturing CO2 after oxygen enriched combustion of converter gas and applying it to converter smelting" is put forward.The new process idea could use oxygen enriched combustion of converter gas to enrich CO2 in flue gas in order to reduce the investment and operation cost of CO2 capture,which is helpful to promote the development of large-scale CO2 capture resource utilization technology in iron and steel industry.The effects of auxiliary gas composition,equivalence ratio,circulating flue gas and preheating temperature on oxygen enriched combustion characteristics and flue gas properties of converter gas are analyzed.Sch-3 with equivalence ratio of 0.9 is determined to be the most suitable combustion scheme for CO2 capture process;The CO2 content in the flue gas is stable at 74.32%after four cycles.Although the preheating temperature reduces the generation of NOx in the flue gas,it has no effect on the CO2 content in the flue gas.The carbon emission and efficiency of different CO2 capture processes are studied.It is found that the carbon emission factors of C-PRO-1,C-PRO-2,C-PRO-3 and C-PRO-4 processes are 3.7811 tCO2/km3,3.2057 tCO2/km3,1.8553 tCO2/km3 and 0.8701 tCO2/km3 respectively.The product efficiencies are 9.76%,6.71%,4.34%and 4.51%respectively,while the recovery efficiencies are 9.76%,6.71%,18.27%and 19.01%respectively.The material balance and energy balance models of converter top and bottom combined blowing CO2 smelting are established,and the industrial test of CO2 smelting is carried out.It is determined that the maximum proportion of CO2 injection is 14.71%,and the gas and steam cycle as the input of capture process will not affect the energy balance;The CO2 emissions of U-BOU-1 boundary and U-BOU-2 boundary are 165.5 kg/t and 138.2 kg/t respectively,the exergy losses are 7.17%and 5.98%respectively,the exergy efficiencies are 92.83%and 94.02%respectively,and the exergy efficiencies of main product are 84.75%and 85.01%respectively.The carbon emission,efficiency and economic indicators of the new process idea(PRO-4 process)are evaluated.It is found that the CO2 emission of PRO-4 process is 0.1404t/t,which is reduced by 25.13 kgCO2/t,16.91 kgCO2/t,13.57 kgCO2/t and 5.72 kgCO2/t respectively compared with conventional smelting,PRO-1,PRO-2 and PRO-3 processes;The operation cost of C-PRO-4 process is 247.64 yuan/km3CO2,which is 39.5%,55.5%and 26.3%lower than that of C-PRO-1,C-PRO-2 and C-PRO-3 processes respectively.The research results provides a reference basis for the new process of"converter steelmaking CO-CO2 mass energy conversion and self recycling".In the meantime,it is a contribution to the further development of CO2 capture and utilization technology in iron and steel industry.更多还原