Mathematical Modelling of an Annealing Furnace for Process Control Applications

Optimisation and improved control of the annealing furnace on a continuous galvanising line was investigated by the construction of a series of mathematical models to predict furnace and strip temperature and strip recrystallisation under both steady and transient states. A modelling approach is followed due to the very poor measurability of temperatures inside the furnace, affected by strong reflected radiation. A 3D Model is used to investigate the temperature distribution of the steel strip and the furnace thermocouple probes, and information from the 3D model enables the construction of a highly simplified 1D/2D model. Combining the 1D/2D model with a steel recrystallisation calculation allows the system to be used for rapid simulation of furnace operating conditions. This is applied to the most common products processed on the plant, resulting in identification of several opportunities for increased production rate and increased energy efficiency.