Asymptotic Model of Refractory and Buildup State of the Blast Furnace Hearth

Wear of the hearth refractory and buildup (“skull”) formation play important roles for the life length of the ironmaking blast furnace. The extent of these factors during the campaign can be estimated by solving a sequence of inverse heat-conduction problems, but this requires thermocouple measurements in the lining and the effect of liquid flow is often disregarded. The model developed in the present paper aims at providing a theoretical estimation of the asymptotic inner profile of the hearth by a CFD-based approach that estimates both the iron flow and the refractory erosion and possible skull. The profile, shaped by the flowing hot metal, solidified skull, and remaining refractory, is obtained through an iterative process based on the calculated fluid flow and temperature distribution in the domain. The paper presents the assumptions behind the model, its main equations and the solution procedure, as well as a set of illustrative examples that show the versatility of the approach. The results of the model can be used to estimate the potential strengths and weaknesses of a specific hearth design and also how the lining state would be affected by changes in the boundary conditions.