Estimation and prediction of unmeasurable variables in the steel mill soaking pit control system

The objective of the soaking pit operation in the steelmaking process is to equalize the temperature throughout the steel ingot masses at some prespecified temperature before the ingots may be rolled at the rolling mill. The ingot temperature, though, is not measurable directly and must be estimated using some indirect measurements (pit wall temperature, fuel flow, etc.). Another piece of information which is important for the whole operation, and specifically for the operation planning purposes, is the predicted moment of time at which the ingots will arrive at the said prespecified temperature. This paper describes a Kalman filter approach and some results of a joint project of General Electric Company-U.S. Steel Company on the estimation and prediction of the ingot temperature in the soaking pit operation.