Accurate Control of Mould Level in Continuous Bloom Casting

This paper describes a case study of advanced control in continuous bloom casting. The study employed nonlinear identification techniques to improve physical understanding of the process. As a consequence, the primary cause of control difficulties in the existing design was found to be slip-stick friction in the hydraulic slide gate valve. A new controller was then designed to compensate for this key nonlinear effect. The new control strategy reduced the magnitude of the previously observed oscillations on the mould level by a factor of ten to one. Subsequent analysis revealed a considerable economic impact resulting in potential savings of many hundreds of thousands of dollars.