高炉炉缸“自保护”凝壳生长/消蚀动力学基础研究

The bottleneck zone determining the campaign life of a blast furnace is moving to its hearth in the current situation of high operation intensity and low-quality raw materials and fuels. The consumption and erosion of hearth linings are inevitable during production process. In order to guarantee long-term safety, it is of essential importance to create a non-overheated hearth system and to generate a stable layer of skull existing between the molten melts and lining materials. In the present time, however, it is still lacking in fundamental research particularly pertinent to the protective skull in blast furnace hearth. Therefore, the current project is focused on the main scientific issues related to rate process of hearth skull phenomena utilizing the theories of metallurgical physicochemistry, metallurgical transport principles, metallurgical macro kinetics and solidification of high-temperature alloy melts. In the project, a series of in-depth theoretical and experimental studies are carried out, aimed to determine quantitative correlations of convective heat and mass transfer coefficients concerning with a boundary layer of high temperature and physical properties variations, as well as the qualitative temperature. Efforts are also put into revealing underlying mechanisms for the evolutions of skull physical properties, which are then quantitatively characterized. After that, a comprehensive macro kinetic model is established. The building and melting processes of blast furnace hearth skull are simulated and analyzed by utilizing the macro kinetic model and the corresponding controlling steps are estimated, serving as a basis for exploring technical measures to timely adjust the state of hearth skull. Therefore, the results of this project could provide preliminary scientific guidance for multi-physics co-protection of blast furnace and extension of its campaign life.

在高冶炼强度和低原燃料品质的当下，限制高炉寿命的瓶颈部位正转向炉缸。高炉炉缸内衬在生产过程中的耗损不可避免，所以创造无过热炉缸体系，形成稳定热面凝壳，是隔绝高温熔体与衬材，保障炉缸长期安全的根本途径。然而，目前具体以炉缸凝壳为题的基础性研究仍不多见。有鉴于此，本项目以冶金物理化学、冶金传输原理、冶金宏观动力学及高温合金凝固等理论为基础，围绕高炉炉缸凝壳现象速率过程所涉及的主要科学问题进行深入系统的理论和实验研究，旨在确定大温差变物性边界层对流传热/传质系数的定量关系式及合理的定性温度、揭示炉缸凝壳物性参数变化规律并对各物性参数进行定量表征，最终建立相应的凝壳生长/消蚀过程宏观动力学模型。同时，应用上述模型，对高炉炉缸凝壳生长/消蚀过程进行综合模拟解析，进而确定相应条件下的限制性环节，探讨及时调控高炉炉缸凝壳状态的技术手段。项目成果可为实现多物理场协同护炉和延长高炉寿命提供先期科学指导。

受高冶炼强度和低原燃料品质的影响，限制炼铁高炉寿命的瓶颈部位正转向炉缸。由于高炉炉缸内衬在生产过程中的耗损不可避免，所以采用较高导热系数衬材，配备高效冷却设备，以炉缸内熔融铁水为原料，在衬材热面形成“自保护”的凝壳，是隔绝内衬与高温渣铁接触，从而保障炉缸长期安全的根本途径。然而，目前具体以炉缸凝壳为研究对象的基础性工作仍不多见，导致对凝壳现象本质的认识尚待深入。本项目针对高炉炉缸铁口以下侵蚀严重区域的铁水-炭砖体系，开展了关于铁基凝壳的系统研究，在其基础上探索了合理调控炉缸凝壳状态，进而延长高炉寿命的技术方法。项目成果可为实现多物理场协同护炉和延长高炉寿命提供先期科学指导，具有显著现实意义和参考价值。本项目主要研究进展和结果为：（1）结合高温实验结果、经验公式和热力学软件，建立了可用于计算高炉炉缸近热面处流体碳含量，进而预测其密度、黏度、导热系数以及碳元素扩散系数的通用模型。模型研究结果表明高炉炉缸近热面处流体的主要物性参数与温度的线性关系良好，故可将边界层内平均温度作为定性温度使用；（2）基于边界层理论、冯卡门积分方法以及雷诺类似律，推导了可用于表征高炉炉缸凝壳生长/消蚀传热过程Nu、Re和Pr数以及传质过程Sh、Re和Sc数的定量关系式；（3）设计并搭建了可进行高炉炉缸凝壳生长/消蚀过程动力学的高温实验设备，验证了实际生产中炭砖与冷却壁间气隙对凝壳行为的决定性影响。对凝壳微观形貌进行了相关研究，发现炉缸凝壳内析出石墨的结构特征自凝壳冷面至热面有很大差别；（4）耦合流动、传热和传质，建立了高炉炉缸凝壳生长/消蚀过程动力学模型，考察了陶瓷杯壁厚度对炉缸热面凝壳生成过程的影响，研究结果可用于指导炉缸衬材的选择；（5）结合数值传热学、有限元法及遗传算法，开发了能够预测高炉炉缸内衬轮廓的仿真系统，不仅可用于预测不同类型的残衬和凝壳双轮廓内型，还能计算特定内型对应的炉缸容积及炉底和炉壁热损失。