高炉喷煤新技术的研究

The new technology, “gas made from coal→ gas injection in blast furnace”, is presented in this project which can substitute the present pulverized coal injection technology. The basis theories of the blast furnace by gas injection (OGBF) and gas-making-oven(GMO), and so on, are importantly researched. The operation state of OGBF is simulated by “multifluid model”. The heat .balance rules and characteristics, and the relationship of technique parameters and coke ratio are studied in order to require the limit coke ratio theory of OGBF. The thermodynamics and kinetics theory of hydrogen reduction in blast furnace are established by exploring the effects of H2 content on heat balance, direct reduction, and indirect reduction. The gas distribution, the resistance loss and temperature distribution are researched, the aim of which is to disclosure the rule of pneumatics and temperature distribution of OGBF. The reaction thermodynamics and kinetics rules of GMO are obtained by studying operation status and technique of gas with H2-rich. The control measures of techniques containing coal election, temperature control, gas flow distribution, and slag-tap in GMO are formed. The effects of circulation quantity and recycle ratio of blast furnace top gas on the quality of gas made from coal are researched, which is to acquire the basis theory data of circularly utilizing blast furnace top gas. Based on the above researches, the fundamental theories of thermodynamics, kinetics, combustion and fluid mechanics in OGBF and GMO are established which provide theory basis for the new technology of gas made from coal→gas injection in the blast furnace.

本项目提出煤造气→高炉喷吹煤气新喷煤技术，以代替现有的高炉喷煤工艺，重点研究喷煤气高炉和造气炉反应的基本理论等关键问题。通过“多流体模型”模拟研究，揭示喷煤造气高炉的运行状态；通过研究喷煤造气高炉的热平衡规律及特点、各工艺参数和焦比之间的关系等，获得喷煤造气高炉极限焦比的相关理论；通过研究 H2 含量对高炉热平衡、直接还原、间接还原的影响，建立高炉氢还原热力学和动力学基本理论；通过研究喷煤造气高炉气流分布和阻力损失特点、温度分布规律等，揭示喷煤造气高炉气体力学和温度分布规律；结合造气炉运行状态和煤造气富 H2 等技术的研究，获得造气炉内燃烧反应、碳气化反应的热动力学规律，建立煤种选择、温度控制、气流分布及排渣等工艺控制基础；通过研究炉顶煤气循环量、循环比等对煤造气质量的影响，获得高炉炉顶煤气循环利用的基础理论数据。基于上述研究，构建喷煤造气高炉及造气炉热力学、动力学、燃烧学和流体力学基础。

喷吹煤造气高炉是把风口前煤粉燃烧气化这一复杂物理、化学过程转移到炉外的新喷吹工艺。它简化了高炉冶炼反应过程，可大幅度提高喷煤量，降低焦比；实现高炉富氢冶炼，生产效率大大提高，成本降低；循环高炉炉顶煤气降低了环境污染。围绕研究目标，开展了喷吹煤造气高炉运行状态、还原热力学、动力学、渣铁形成过程及渗碳特点、极限焦比、煤气中H2含量对冶炼的影响及合理利用、造气炉内反应机理及技术、高炉炉顶煤气合理循环利用的研究。.由高炉反应数学模型得到，喷吹煤造气高炉流场更加均匀、炉料透气性提高、气相与固相间温差增大换热加强、还原速率加快生铁产量增加；构建了喷吹煤造气高炉反应热力学和动力学理论，得到CO-H2还原矿石特点，确定了反应限制性环节；试验研究得到喷吹煤造气高炉初渣形成比传统高炉提前，初渣组成接近终渣组成，金属铁渗碳速率远低于炉料还原速率；由理论计算得到喷吹量为775Nm³/tFe时，喷吹煤造气高炉焦比达到理论最低值273.36kg/tFe，喷吹的煤气理论上可替代83.6kg/tFe的焦炭，且富氧率在8.25%以上可满足理论燃烧温度在1900℃以上的要求。. 随煤气中H2含量的增加，高炉内直接还原度降低，间接还原度增加，热量收支差逐渐减少，由试验研究得到煤气中H2含量对炉料冶金性能的影响。由高炉反应数学模型计算得到，喷吹煤造气高炉喷吹的煤气量为600～800Nm³/tFe，富氧率20%～30%，炉腹煤气H2含量10%～15%，CO含量45%～60%，与传统高炉对比，产量提高11.06%～26.51%，渣量降低10.68%，CO的利用率为60.11%。. 由理论和试验研究得到最佳配煤、配气方案和调控煤气含氢量技术，煤灰分、反应温度、时间和气化剂流量与煤气中（CO+H2）的关系；通过调控技术得到煤量为285kg/tFe，富氧率为20.3%，喷入水蒸气14kg/tFe时，造气炉的煤气产量为700m3/tFe，煤气中的H2为20.55%，CO为46.21%，提高鼓风温度至1200℃，煤气出口温度控制在1000℃左右，出口压力可达到372.27kPa。试验研究得到煤燃烧、气化的热力学、动力学规律和调渣技术；通过炉顶煤气循环数学模型得到炉顶煤气循环四次后高炉和造气炉的进出气体成分、热量等参数达到稳定。