Billet Heating Time Forecast when Implementing Optimal Control of Heating Process with Regard to Mill Performance

Pre-rolling slab heating furnaces are throughfeed heating systems. A furnace is an element of the rolled sheet process flow and its yield is directly dependent on the rolling mill yield. To implement optimal heating schedules, it is necessary know the slab heating time when loading a slab in the furnace. The author evaluates a method of predicting heating time for each slab accounting for the expected rolling mill yield and downtime due to operational shutdowns. Special attention is given to the procedure for slab heating time correction in the event of nonscheduled rolling mill downtime. Nonscheduled rolling mill shutdowns are accidental and unpredictable events caused by breakdowns in the technological process or failures of equipment elements. The author describes a method of routine slab heating time correction in the event of rolling mill's process equipment accidents. The developed heating time prediction algorithm was implemented and tested using the rolling mill at Magnitogorsk Iron & Steel Works, PJSC, Magnitogorsk. The comparison of the predicted and actual heating time demonstrated that the absolute error of slab heating time prediction does not exceed 12 minutes when the total heating time is 180 minutes.