Open Access Conference Proceedings

With rising energy costs, efficient and accurate heating of the charge to rolling temperature is critical to reducing operating costs and improving the quality of the finished product. The surface temperature of the charge obtained from non-contact measurements after exiting the furnace does not provide information about the internal temperature of the charge, nor does it reveal the temperature profile prior to exiting the furnace. As a result, charge overheating, low internal temperature, or insufficient soaking time at target temperature may go undetected. This paper presents a methodology that includes operational temperature measurements inside steel blooms throughout the heating process in industrial furnaces and subsequent numerical calculation of the heat transfer coefficient. The operational measurements were carried out using thermocouples placed inside circular continuously cast semi-finished product, which allowed precise monitoring of the temperature profile throughout the heating process. The data showed that the furnace design significantly affects the thermal homogeneity of the furnace charge. In a rotary hearth furnace, a significant influence of the furnace bottom on the thermal homogeneity of the charge was observed, especially when the bloom was in full contact with the bottom. To better understand these phenomena, a numerical inverse calculation was performed to determine the heat transfer coefficient as a function of position and temperature within the furnace. This coefficient is critical for accurate numerical modelling of the heating process without the need for complex combustion flow and radiative exchange calculations. Knowledge of the heat transfer coefficient allows process optimization, minimization of energy consumption, and improvement of final product quality. The results presented provide valuable insights into industrial practice and demonstrate possible approaches to improve heating efficiency.

Keywords: Heating, temperature measurement, heat transfer coefficient, inverse calculation

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