Thermomechanical Behavior of Steel Ladle Linings and the Influence of Insulations

Refractory linings of steel ladles are usually exposed to considerable thermomechanical loads caused by temperature gradients and different thermal expansion coefficients of refractory material and steel construction. Highest temperatures and compressive stresses appear at the hot face in circumferential direction. For common refractory materials this leads to irreversible compressive strains. If these strains are exceeding a critical value and the lining shows further radial displacement joints between bricks will open. Hence the joint opening depends on the lining design, material properties, and process conditions. A new group of refractory materials can counterbalance the irreversible strains by controlled expansion (CE) during service. For a selected steel ladle the value of required expansion was calculated to achieve closed joints at the hot face. Therefore, a Finite Element simulation was set up and the influence of lining design, material properties, and preheating conditions was determined. Special interest is attributed to an occasionally applied insulation. On the one hand it increases the lining temperature and decreases the steel shell temperature. Both factors increase the thermomechanical stress. On the other hand a relatively low stiffness of insulating materials reduces the stresses. The impact of insulation on the required CE is discussed in the results.