Multiphysics Model of the Hearth Lining State

Abstract

The campaign life of the blast furnace is governed by the erosion of the hearth lining. Therefore, it is essential to keep track of the residual lining thickness not only for the better planning of the relining but also for the operational safety to avoid dangerous hearth breakthrough incidences. Modern blast furnaces are equipped with many thermocouples in the hearth refractory to monitor the temperature level. Higher temperatures indicate a lower residual wall thickness. However, the measured temperatures are also influenced by many other effects such as thermocouple defects, brittle layers in the refractory, hearth cooling system, production rate, temperature, and flow state of hot metal. Existing models lack comprehensive checks of the data plausibility or of possible effects unrelated to wear. The new multiphysics approach provides a flexible platform to include these influences as well as other physical aspects that are important for operational hearth monitoring. For instance, thermal stresses and the deformation of the hearth lining and steel shell can be analyzed. This enables the integration of strain‐gauge measurements into the model which were recently suggested for the monitoring of liquid levels. The numerical computations and visualization are performed using COMSOL Server with MATLAB for the 3D hearth geometry. This enables the use of a standard web browser to visualize the results interactively on any device connected to the internal network without any local software installation. The developed multiphysics model is calibrated and validated by comparing the estimated wear profile with the measured residual wall thickness during the blast furnace relinings in 2016 at Eisenhüttenstadt and Dillingen. Two instances of the multiphysics model are online and in use for monitoring the hearth lining state at these plants.