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烧结废气最高温度变化规律、影响机制与调控研究进展

Research progress on variation patterns, influencing mechanisms and control of maximum temperatures in sintering exhaust gases

  • 摘要: 烧结废气最高温度可反映料层燃烧带推进与气固传热强度,并可作为终点热态稳定性的外部量化指标,与烧结终点位置相关但不等同。基于工业监测结果与机制研究,烧结废气温度沿机长方向呈现先低后高再回落的空间分布。机头湿料带受蒸发吸热与换热限制温度偏低,随干燥预热完成及燃烧带下移逐步升高,在燃烧带推进至料层底部、接近烧穿点时达到最大值,进入机尾后段逐渐下降,且对工况扰动较为敏感。烧结废气最高温度受燃料、工艺与原料3类因素耦合影响,燃料粒度细化和混合料水分增加可降低峰温;提高配碳量、点火强度和料层厚度则会升高峰温;碱度及其调节方式通过影响液相生成与热平衡改变高温区热强度。温度过低易导致液相不足、黏结相发育受限而强度下降;温度过高或高温持续时间过长则可能诱发过烧并促进薄壁大孔结构形成,影响烧结矿质量。未来应面向“质量-能耗-排放”协同目标,结合机制与数据驱动方法开展烧结废气最高温度在线表征与调控研究,支撑低碳烧结发展。

     

    Abstract: The maximum temperature of sintering exhaust gas reflects the advancement of the combustion zone within the material bed and the intensity of gas-solid heat transfer. It serves as an external quantitative indicator of terminal thermal stability, correlating with but not equating to the precise location of the sintering endpoint. Based on industrial monitoring data and mechanistic studies, the temperature distribution of sintering exhaust gas along the machine length exhibits a spatial pattern of initially low temperatures, followed by a rise and subsequent decline. The wet material zone at the machine head exhibits lower temperatures due to evaporation heat absorption and heat exchange limitations. Temperatures gradually increase as drying and preheating are completed and the combustion zone descends, reaching a maximum when the combustion zone advances to the bottom of the material bed and approaches the burn-through point. Temperatures then gradually decrease in the rear section of the machine tail and are relatively sensitive to operating condition disturbances. The peak sintering exhaust gas temperature is influenced by the coupled effects of fuel, process parameters, and raw materials. Finer fuel particle size and increased mixture moisture content reduce peak temperature. Higher carbon content, ignition intensity, and bed thickness elevate peak temperature. Alkalinity and its regulation methods alter thermal intensity in high-temperature zones by affecting liquid phase formation and thermal equilibrium. Excessively low temperatures may lead to insufficient liquid phase formation, restricted development of the sintered phase, and reduced strength. Conversely, excessively high temperatures or prolonged exposure to high temperatures may induce over-sintering and promote the formation of thin-walled, large-pore structures, adversely affecting sinter quality. Future research should focus on the synergistic objectives of "quality-energy consumption-emissions", combining mechanistic and data-driven approaches to investigate the online characterization and regulation of the maximum sintering exhaust gas temperature, thereby supporting the development of low-carbon sintering processes.

     

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