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氢基竖炉高氢区炉衬耐火材料侵蚀行为与机制

Corrosion behavior and mechanism of refractory linings in high-hydrogen zone of hydrogen-based shaft furnace

  • 摘要: 为评价氢基竖炉高氢区域炉衬耐火材料在强还原气氛中的服役稳定性,并明确不同材料在高H2分压条件下的物相、显微结构和性能响应规律,本文首先采用Fluent软件计算炉壁温度、压力及气体组成分布,确定还原段中下部和还原气入口附近为高温、高H2分压的关键位置,并以此作为930 ℃ H2还原试验的工况依据。以I等高铝砖、Ⅱ等高铝砖、刚玉-SiC微孔砖、Sialon-刚玉砖及Si3N4-SiC砖为研究对象,在930 ℃ H2中保温5、10、15、20、25 h,结合X射线衍射(X-ray diffraction,XRD)、扫描电子显微镜(scanning electron microscopy,SEM)以及质量、体积密度、显气孔率和常温耐压强度测试,考察物相结构与宏观性能的响应规律。结果显示,Al2O3骨架相在该条件下保持稳定,而SiO2、Fe2O3、TiO2等敏感组分更易参与还原反应或结构重排。25 h后5种材料的质量变化率依次为-0.318%、-0.477%、+0.063%、-0.044%和-0.262%。其中,Ⅱ等高铝砖失重最大,表明较高SiO2和Fe2O3含量会削弱其在高H2气氛中的稳定性;刚玉-SiC微孔砖质量变化最小,其体积密度增加、显气孔率下降,表现出较好的结构保持能力和抗H2渗透能力。综合分析认为,高H2区炉衬材料的侵蚀可描述为H2经开口气孔和微裂纹进入材料内部,诱发活性组分还原或重构、孔隙网络变化以及力学性能响应的耦合过程;材料抗侵蚀性主要受组分热力学稳定性、气孔连通程度和结合相演化共同制约。研究结果可为氢基竖炉高H2区炉衬材料的筛选与优化设计提供依据。

     

    Abstract: To evaluate the service stability of refractory linings in the high-hydrogen zone of hydrogen-based shaft furnace under strong reducing atmosphere, and clarify the response laws of phase, microstructure and properties of different materials under high H2 partial pressure, Fluent simulation was first used to calculate the furnace-wall temperature, pressure, and gas-composition distributions. The middle-lower part of the reduction section and the region near reducing-gas inlet were identified as key locations with high temperature and high H2 partial pressure, and were taken as the basis for the 930 ℃ H2 reduction experiment. Grade I high-alumina brick, Grade Ⅱ high-alumina brick, corundum-SiC microporous brick, Sialon-corundum brick, and Si3N4-SiC brick were selected as the research objects. The samples were held in H2 at 930 ℃ for 5, 10, 15, 20, 25 h. X-ray diffraction (XRD), scanning electron microscopy (SEM), mass change, bulk density, apparent porosity, and cold compressive strength tests were used to investigate the evolution of phase structure and macroscopic properties. The results show that the Al2O3 skeleton phase remains stable under the experimental conditions, whereas sensitive components such as SiO2, Fe2O3, and TiO2 are more likely to participate in reduction reactions or structural rearrangement. After 25 h, the mass change rates of the five materials are -0.318%, -0.477%, +0.063%, -0.044%, and -0.262%, respectively. Among them, Grade II high-alumina brick exhibits the largest mass loss, indicating that higher contents of SiO2 and Fe2O3 weaken its stability in a high-H2 atmosphere. The corundum-SiC microporous brick shows the smallest mass change, together with increased bulk density and decreased apparent porosity, indicating good structural retention and resistance to H2 penetration. Comprehensive analysis indicates that corrosion of lining materials in the high-H2 zone can be described as a coupled process involving H2 penetration into the material through open pores and microcracks, reduction or reconstruction of active components, pore-network evolution, and mechanical-property response. The corrosion resistance is mainly controlled by the thermodynamic stability of components, pore connectivity, and bonding-phase evolution. This study provides a reference for the selection and optimized design of refractory linings in the high-H2 zone of hydrogen-based shaft furnaces.

     

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