Specification Framework for Control of the Secondary Cooling Zone in Continuous Casting

Abstract

A model describing heat transfer in the secondary cooling zone (SCZ) of a continuous caster is derived. In order to reduce the defects arising from improper cooling in the SCZ of a continuous caster, a simple open-loop control strategy is proposed and evaluated. This means that with the aid of an equivalent numerical model of the SCZ, the heat transfer coefficients are found which deliver an ideal or near-ideal temperature profile along the midface of the strand. The temperature profile is specified by the user, and strongly depends on characteristics of the steel and physical constraints of the water cooling system of the continuous caster. Two examples highlighting the open-loop control approach are shown for a low carbon 14 cm×14 cm billet caster. Simulations show that a temperature profile can be achieved with open-loop control that differs only slightly from the specified temperature profile.
Casting speed, rollers and clogged sprays are the main disturbances that can cause the temperature profile to deviate from ideal. The influence of these disturbances is shown.