An Experimental Technique for Investigating the Skulling Behavior in the Blast Furnace Hearth

Abstract

The skulling behavior in the blast furnace (BF) hearth has yet to be investigated as few (if any) industrial/experimental studies with particular focus on hot metal are reported in the open literature. As a necessary first step toward a better understanding of the sophisticated behavior, an experimental technique is introduced in the present paper. The experimental apparatus, which mainly consists of a vertical tube furnace, a rotating and moveable pedestal, and a moveable water‐cooled probe covered with a multi‐layer structured refractory sleeve can utilize industrial coke, pig iron, and BF hearth carbon brick as raw materials. The technique is shown to be capable of producing chemical, thermal, and mechanical conditions similar to those in the real process. The feasibility and potential of the technique are demonstrated by a set of experimental runs. The results indicate that the air gap between the cooling device and the refractory lining plays a decisive role in both skull formation and lining erosion. Furthermore, the microstructure of graphite precipitated during solidification is influenced by the cooling rate, which in practice is affected by the BF hearth operating parameters. It is hoped that the current contribution will stimulate the growing research interest in this subject.

Numerical Simulation Model for Evaluating Protection Measures of Blast Furnace Hearth

“…The solidified iron layer in the depression erosion area has completely disappeared, leaving only the mushy area. This is the same as the conclusion of the experiment in the literature [10]. The existence of the air gap directly destroys the stable thermal cycle state of the hearth…”

“…In the thermofluid coupling calculation model, the convection heat transfer coefficient of the side walls of the hearth was equivalent and calculated by using the convection heat transfer boundary replacement method of the long cylinder [30]. The equivalent convection heat transfer coefficient of the side walls of the hearth (h c ) was calculated by Equations ( 7)- (10). The convection heat transfer coefficient of the furnace bottom was 40 W/m 2 •K, and all other boundaries were adiabatic boundaries.…”

“…Improving the cooling intensity of the furnace hearth can reduce the temperature of its hot surface [9,10]. The accumulation of heat in the hearth is avoided in this way.…”

Numerical Estimation of Hearth Internal Geometry of an Industrial Blast Furnace

“…[1][2][3][4] In the practical operation, the hearth walls are routinely cooled with surface or embedded water circuits and the liquid iron ("hot metal") in the vicinity of the hot face may therefore solidify to form a build-up ("skull") layer acting as an autogenous barrier to protect the remaining lining. [5,6] However, an excessive growth of skull is detrimental as it reduces the effective hearth volume and consequently the possibilities to maintain a high production rate. Timely monitoring and proper control of the hearth internal geometry reflecting the state of lining erosion and skull buildup are, therefore, essential steps toward successful BF operation with a long campaign and a high production rate.…”