Computationally efficient alternative to a full-scale transient simulation of a reheating furnace

Abstract

Reheating of steel slabs in a reheating furnace is an intermediate step in the long and complicated process of steel making. Reheat furnaces heat the slabs to about 1200°C, which makes the steel suitable for hot rolling. During this reheating process temperature uniformity within the slab is very important. A detailed understanding of the reheating process is hence, important both from the perspective of product quality and energy use. Unfortunately, the extreme conditions inside the furnace do not allow for a detailed experimental investigation. Numerical tools like Computational Fluid Dynamics are useful in such situations, but full-scale transient models often lead to unpractically high computational costs. In this paper, a Truncated Transient Slab Model is validated, which is capable of predicting the transient behaviour of the slab during reheating in a computationally efficient way. This is accomplished by coupling two different models: a steady-state model of the complete furnace and a transient model of the truncated domain around a single slab. The truncated domain replicates the flow conditions of a full-scale transient model in a much smaller domain. The advantage of this modelling approach when compared to full-scale transient models is a significant reduction in simulation time (just 4 days) while maintaining a high grid resolution. Compared to the experiments, the simulations have an average accuracy of 4-5% for the entire range of reheating temperatures(28– 1200°C) for both the slab surface and the core. The error on the slab drop-out temperature was about 2% at a measured temperature 1185°C.