炼铁高炉多物理场耦合跨尺度数值建模及内部热化学行为研究

Ironmaking blast furnace (BF) process, proceeding under a high temperature and a high pressure, is largely operated as a “black box” due to its inner complicated multi-phase flow (gas, liquid, solid and powder etc.) and multi-physics-coupled (force field, temperature field, and chemical composition field). It has been realized that the mathematical model can be taken as an effective method to know, study and further guide practical BF operation based on the fact that the current practice largely depending on empirical experience. This project, based on advanced multi-scale-coupled CFD-DPS approach, aims to develop a multi-phase flow BF model by creatively overcoming various challenges in high-temperature process modeling. Generally, the studies are listed as follows: The present work firstly develops a multi-phase (gas, liquid and solid) and multi-scale-coupled mathematical BF model which considers heat and mass transfer in a solid particle, and then study the theoretical speedup mechanism for the multi-phase transition processes and investigate its inner thermochemical behaviors evolution periodically; Secondly, it will examine the void fraction variations and its related chain reactions due to solid particle shrinkage and degradation, stress change etc. in dry zone, and explore the relations between the cohesive zone profile variation and some key variables such as burden distribution and gas inlet condition, additionally investigate the interactions of gas, liquid and solid in dripping zone, and finally provide scientific support and theoretical basis for improving BF operation efficiency and decreasing energy consumption under some new operation conditions.

炼铁高炉内部是高温高压环境下的多相物质流（气、液、固、粉相等）多物理场（力场、温度场、化学组分场）复杂耦合的“黑箱”。基于目前高炉操作还主要是依靠生产经验的事实，采用数学模型来认识、研究进而指导高炉操作被视为一种有效手段。本项目采用基于先进的CFD-DPS多相流耦合方法跨尺度数值建模进行研究，以突破炼铁高炉多相高温过程模拟中的科学难题，主要开展如下研究：首先建立考虑固相颗粒内部热质传输，同时与气相、液相的多物理场耦合的高炉数学模型，研究多相流传输过程的理论加速规律并探明全生产周期高炉内部演变机制；然后考察高炉块状带内因颗粒收缩粉化、应力变化等引起的孔隙度变化等连锁反应，明晰软熔带的形貌和位置变化与布料制度、送风条件等重要变量的关系，并探明滴落带内气、液、固相间传输过程的相互作用关系，进而为实现高冶炼强度等新型条件下提高高炉工作效率、降低高炉能源消耗等目标提供理论基础及技术支撑。

传统炼铁高炉过程的能耗与CO2排放均占钢铁生产的70%左右，研发低碳高炉是实现钢铁工业“双碳”目标和高质量发展的重大需求。本项目主要围绕“炼铁高炉多物理场耦合跨尺度数值建模及内部热化学行为”进行研究，从炼铁高炉内部多相流传输过程的研究出发，发展了考虑气体与焦炭反应物性变化及铁矿石熔化相变的多流场模型与模拟方法，获得了高炉内部如颗粒尺度的作用力和流动结构等微观信息，揭示了铁矿石熔化相变的动态演化规律和影响机制，建立了不同类型焦炭颗粒的运动轨迹分布图，提出了优化及分析风口回旋区形貌的方法，阐明了高炉内部多元多相物质流在多物理场作用下的理化性质的时空演变规律。得出主要结论如下：（1）回旋区的宽度和高度随着鼓风速率的增大而增加；鼓风速率的上升使气体高温区和化学反应区分布发生改变，即最高温度点和焦炭反应区均向焦炭床中心移动。（2）通过解析不同工况条件下单矿石颗粒还原模型中气膜阻力的影响，发现气膜阻力可带来最大约3.00%的计算误差；铁矿石颗粒粒径大小对加热熔化过程的液相析出、相变区厚度和颗粒中心与外表面温差影响最为显著。（3）针对颗粒移动床反应器内的多相流传输过程采用相似理论原理，通过对炉内多物理场的耦合现象（包括热量和质量传输、化学反应）的广泛模拟，提出了结合过程特点的合理加速规律。（4）炉内料批重减小21.50%，炉料平均温度降低约5.81%，软熔带高度缩减约8.00%，炉内矿石还原度降低约3.10%，反之亦然，表明在料批重发生增加或减少21.50%时，当料批重恢复时，当前操作的高炉主要运行参数及特征可以恢复先前水平。. 围绕本项目研究内容，发表相关学术论文17篇，出版专著1部，授权发明专利1项、软件著作权6项，参加国内外学术会议8次并作报告，培养毕业硕士生7名（3名已毕业）。