Prediction of transient slab temperature distribution in the re-heating furnace of a walking-beam type for rolling of steel slabs

Abstract

This article is on heat transfer analysis by the commercial code, FLUENT, for slabs heated in a walking beam type of a re-heating furnace in POSCO (Pohang Iron & Steel Co., Ltd.). Steady state, three-dimensional analysis is performed for turbulent reactive flow and radiative heat transfer in the furnace. Computation is based on the Favre-averaged conservation equations of mass, momentum, energy and species with the k-ε turbulence model. The predicted global energy flow is in good agreement with the measurement. Two-dimensional transient calculation is performed for conduction in a slab with the boundary condition given in terms of the calculated local heat flux in the furnace. Results show substantial variation of the temperature across the furnace as well as between skid and non-skid regions in the slab. Parametric study is performed to examine skid mark severity and energy loss to the skid system with respect to the height and shape of the skid button and the convective heat transfer coefficient to cooling water. It is shown that the radiative exposure, which depends on the height and shape of the skid button, reduces skid mark severity by decreasing heat loss from the slab. The convective heat transfer coefficient to the cooling water turns out not to be of as much significance to skid mark severity as the exposure area of the skid button.