Real-time Model-based Spray-cooling Control System for Steel Continuous Casting

This paper presents a new system to control secondary cooling water sprays in continuous casting of thin steel slabs, CONONLINE. It uses real-time numerical simulation of heat transfer and solidification within the strand as a software sensor, in place of unreliable temperature measurements. The one-dimensional finite-difference model, CON1D is adapted to create the real-time predictor of the slab temperature and solidification state. During operation, the model is updated with data collected by the caster Level 2 automation system. A decentralized controller configuration based on a bank of PI (Proportional-Integral) controllers with antiwindup is developed to maintain the shell surface temperature profile at a desired setpoint. A new method of setpoint generation is proposed to account for measured mold heat flux variations. A userfriendly monitor visualizes the results and accepts setpoint changes from the caster operator. Example simulations demonstrate how significantly better shell surface temperature control is achieved.