高炉炉缸凝铁层的组成分析与导热系数测定

Composition analysis and thermal conductivity measurement of iron skull in blast furnace hearth

高炉炉缸内衬表面形成稳定的凝铁层将保护高炉炭砖并延长高炉寿命。利用光学数码显微镜观察统计分析高炉凝铁层生产样品,探究不同焦炭体积占比对凝铁层导热系数的影响。利用元素分析(XRF)、X射线衍射分析(XRD)、扫描电镜(SEM-EDS)等手段分析凝铁层的组成,并观察其微观形貌。利用瞬态平面热源法(TPS)测定凝铁层的导热系数,进一步分析其组成与导热系数之间的关系。结果表明,凝铁层由铁、充满铁水的焦炭、石墨碳、少量渣相组成,凝铁层内部没有气隙。凝铁层生产样品的导热系数测定范围为27.21~97.38 W/(m·K),导热系数(λ)与其组成的焦炭面积比(S_c=22%~48%)之间的线性关系为:λ=-257.47S_c+157.65。模拟实验凝铁层的导热系数范围为30.54~53.95 W/(m·K),该值远大于目前数学模型中采用的凝铁层导热系数(2~4 W/m·K),随着焦炭粒度的增加,凝铁层的导热系数先增加后减小。凝铁层中导热系数(λ)与焦炭体积分数V_c(V_c=39%~50%)的线性关系为:λ=-80.50V_c+78.56。研究结果进一步明确了凝铁层的物相组成及其导热系数,为高炉长寿的研究指明了方向。

The formation of stable iron skull on the inner surface of blast furnace hearth can protect the blast furnace carbon bricks and prolong the service life of the blast furnace.Optical digital microscope was used to observe and analyze the production samples of blast furnace iron skull to explore the effect of different coke volume ratio on the thermal conductivity of the iron skull.The thermal conductivity of the iron skull was measured by transient planar heat source method(TPS),and the relationship between its composition and thermal conductivity was further analyzed.The results show that the solidified iron skull is consist of iron,coke filled with hot metal,graphite carbon and a small amount of slag phase.There is no air gap in the solidified iron skull.The thermal conductivity of the samples produced in solidified iron skull is 27.21-97.38 W/(m·K),and the linear relationship between thermal conductivity(λ)and coke area ratio(S_c=22%-48%)is as follows:λ=-257.47S_c+157.65.The thermal conductivity of the solidified iron skull ranges from 30.54 to 53.95 W/(m·K).The linear relationship between the thermal conductivity(λ)and the volume ratio of coke in the solidified iron skull is as follows:λ=-80.50V_c+78.56.The thermal conductivity by the volume ratio of coke(V_c=39%-50%)is much larger than of the solidified iron skull(2-4 W/(m·K))used in the current mathematical model.With the increase of coke particle size,the thermal conductivity of solidified iron skull increases first and then decreases.This study clarifies the phase composition and thermal conductivity of the solidified iron skull,and points out the direction for the study of blast furnace longevity.