Latest Evolution in Blast Furnace Hearth thermo-Mechanical Stress Modelling
Résumé
Saint-Gobain has a long experience in the design and supply of blast furnace hearth linings. The Blast Furnace Hearth is arguably the most critical part within the whole integrated steel plant when considering overall potential profit/loss. Typical wear lines found in the BF hearth match closely with the areas subject to highest Thermo-Mechanical stresses. There is clear interest in being able to estimate the thermo-mechanical stresses experienced between different designs. Thanks to FEM tools, SG has a means of evaluating these stresses in the hearth and in order to complete their expertise, they have launched an ambitious program of material modelling and characterization aimed at designing a model as close to reality as possible. The last developments include: - The identification of the mortar joint behaviour as a function of temperature. For that purpose, new compressive tests at high temperature have been developed; - A modelling method with Equivalent Homogeneous Materials for pad as well as walls has been used. This calculation method makes it possible to take into account the behaviour of the very soft and numerous joints. As a consequence, the hearth stiffness is globally reduced; - A precise and appropriate identification of the ramming mix behaviour through a Cap model, defining hardening behaviour in compression. Accounting for this specific behaviour is a key point considering its strain absorbing role due to lining expansion. At the same time efforts are being made to register actual stresses found in the BF hearth. With the results from the improved model calculation and better knowledge of the actual stresses which are experienced, we will be better placed to make advances in the correct direction regarding design considerations.
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