Application of expert system for heating control of Annealing Furnaces in a cold rolling mill - A case study at Bokaro Steel Plant

Steel coils in cold rolling mill of an integrated steel plant are annealed to remove the mechanical distortions ensued by hot and cold rolling. It is an extremely crucial process upon which the final quality of product depends. In annealing process coils are heated following a pre-defined thermal regime and then cooled slowly. Thermal regime or heating cycle basically depends on coil dimensions and steel grade. However in practical there are no well established co-relations are available, which can determine the thermal regime to be followed for a given set of coil parameters. Such indeterminate applications are the fittest areas, where the theoretical concepts of Artificial Intelligence or expert system in particular can be applied in real time process control. A close loop expert system guided heating control system has been developed for Annealing Furnaces of Line # 1 at Bokaro Steel Plant. The integrated automation is based on the concepts of hierarchical control, wherein a Level-II rule based expert system selects most appropriate thermal regime for a given set of steel coils and Level-I PAC controls and supervises the furnace heating operation as per the guidelines of expert system. The application has rendered significant improvement in plants performance in terms of productivity, quality and energy savings.