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冷压块配加对高炉上部炉料分布的模拟分析

Simulation analysis of cold briquette addition on upper burden distribution of blast furnace

  • 摘要: 在钢铁行业绿色低碳转型与冶金固废高效资源化利用的迫切需求下, 铁矿粉冷压块作为低能耗、低排放的新型含铁炉料, 可消纳烧结返矿、冶金粉尘等二次含铁资源, 但其在高炉内的布料行为与炉料适配性研究仍存在明显空缺, 制约了其规模化工业应用。本文以国内某钢厂3 200 m3无料钟高炉的实际生产参数为基准, 采用离散单元法(DEM)构建涵盖称量料管、中心喉管、旋转溜槽及炉喉上部的全流程布料数值模型, 选用Hertz-Mindlin无滑移接触模型描述炉料颗粒间的碰撞、滑动及堆积相互作用, 通过与同工况工业实测数据对标验证了模型可靠性。在此基础上, 系统对比了冷压块形状、替代炉料种类及配加比例对炉料径向偏析及料层压降的影响规律。模拟结果显示, 高炉上部1.8, 2.7)m中径区域是炉料布料的主要初始落点, 炉料堆积密度最高、孔隙率最低, 成为制约整体透气性的高压降区, 基准工况下该区域单位压降达15 000 Pa/m; 不同参数的冷压块均表现出"中心稀疏、边缘集中"的径向偏析特征, 随着配加比例从10%提升至20%, 其边缘富集程度逐渐减弱, 20%配加时径向分布均匀性最佳。椭球形冷压块在3种形状的压块中有着最低的压降; 替代烧结矿时对原有炉料分布扰动最小; 当配加比例超过20%后, 高压降区压降呈非线性急剧上升, 30%配加时单位压降飙升至40 000 Pa/m, 将严重恶化炉料透气性。本研究明确了冷压块高炉应用的最优参数组合, 提出工业生产中应优先采用椭球形冷压块、以替代烧结矿为主且配加比例控制在20%以内的技术建议, 可为冷压块的工业试生产及高炉炉料结构低碳调整提供数据支撑。后续将结合冷压块高温冶金性能开展全流程耦合模拟, 并推进工业高炉配加试验。

     

    Abstract: Driven by the urgent demand for the green and low-carbon transformation of the iron and steel industry and the efficient resource utilization of metallurgical solid wastes, iron ore powder cold briquettes, as a new type of iron-bearing burden with low energy consumption and low emissions, can consume secondary iron-bearing resources including sinter return fines and metallurgical dusts. However, there is an obvious research gap in the burden distribution behavior and burden adaptability of cold briquettes in blast furnaces, which restricts their large-scale industrial application. Based on the actual production parameters of a 3 200 m3 bell-less blast furnace of a domestic steel plant, this study established a full-process numerical model of burden distribution covering the weighing pipe, central throat, rotating chute and upper furnace throat by adopting the Discrete Element Method (DEM). The Hertz-Mindlin no-slip contact model was selected to describe the collision, sliding and accumulation interactions between burden particles, and the reliability of the model was verified by comparison with industrial measured data under the same working conditions. On this basis, the effects of cold briquette shape, replaced burden type and addition ratio on the radial segregation and bed pressure drop of burden were systematically compared.Simulation results show that the1.8, 2.7) m middle diameter area in the upper part of the blast furnace is the main initial landing area for burden distribution. This area presents the highest burden accumulation density and the lowest porosity, forming a high pressure drop zone that limits the overall gas permeability. Under the baseline working condition, the unit pressure drop in this area reaches 15 000 Pa/m. Cold briquettes with different parameters all exhibit the radial segregation characteristic of sparse center and dense edge. As the addition ratio increases from 10% to 20%, the edge enrichment degree gradually decreases, and the radial distribution uniformity reaches the optimum at the addition ratio of 20%. Among the three types of cold briquettes with different shapes, ellipsoidal cold briquettes have the lowest pressure drop and cause the minimum disturbance to the original burden distribution when replacing sinter ore. When the addition ratio exceeds 20%, the pressure drop in the high pressure drop zone increases sharply in a nonlinear manner, and the unit pressure drop surges to 40 000 Pa/m at the addition ratio of 30%, which seriously deteriorates the burden gas permeability.This study clarifies the optimal parameter combination for the application of cold briquettes in blast furnaces, and proposes technical suggestions for industrial production that ellipsoidal cold briquettes are preferentially applied to mainly replace sinter ore with the addition ratio controlled within 20%. The research results can provide data support for the industrial trial production of cold briquettes and the low-carbon adjustment of blast furnace burden structure. Full-process coupling simulation considering the high-temperature metallurgical properties of cold briquettes will be carried out, and industrial addition tests in blast furnaces will be promoted in subsequent research.

     

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