Temperature control of reheating furnace based on distributed model predictive control

In steel industry, reheating furnaces are the biggest energy consumers after the blast furnace. The purpose of a slab reheating furnace is to heat steel slabs to a suitable temperature profile (around 1250°C) before entering to hot rolling phase. The reheating furnace is divided in zones, each zone being controlled independently. In this paper, a model considering the coupling effect between zones is proposed and identified. This model is afterwards used in a distributed model predictive control strategy (DMPC). The experimental results in industrial plant show an energy saving of about 3% while maintaining the heating quality of products. In addition to energy saving, industrial online measurements showed more stable furnace performance, especially in transient (oxygen level, pressure, global air/gas supply).