Determinação de parâmetros de transferência de calor para o modelo transiente do ciclo das panelas de uma aciaria.

Abstract

The steel production at a steel industry should be conducted by seeking continuous improvements in productivity and product quality, at a lower cost. In order to achieve these objectives, the control of the temperature of the liquid steel in the steelmaking is of paramount importance, since the factors that affect the quality of the steel and the reduction of the cost of production are directly affected by the variations in the temperature of the steel. The variations in the temperature of the steel depend directly on the thermal losses during the period of contact with the steelmaking ladles in the stages of the ladles cycles. In this way, the quantification of these thermal losses is of extreme importance for the optimization of the steel control process. However, due to the great variability of the operation dynamics of the ladles and the fact that the thermal phenomena involved in these steps present non-linear behavior, the quantification of these losses does not become an easy task. In addition, in the majority of the works consulted in the literature that deal with the quantification of these losses, the authors consider constant the heat transfer parameters by convection that occur throughout the entire process, however, this consideration becomes inconsistent, since such parameters vary according to the conditions in which the ladles are. In this work, a transient phenomenological model of temperature prediction of the refractory ladles was obtained, and a methodology was applied for the determination of the parameters of heat transfers that involve the cycle of the steelmaking ladles, through minimization of the difference between values obtained by the model and experimental data. The use of this model made it possible to analyze the thermal state of the ladles under different operating conditions, besides providing improvements in the predictions of temperature variations of liquid steel, optimization of the consumption of natural gas, which is used during the heating stage of the ladles. Key words: Steelmaking Ladles, Temperature, Heat Transfer, Thermal Loss, Modeling.