The Study On Temperature Optimal Control Of Walking-Beam Reheating Furnace

Reheating furnace is an important facility on steel's hot-rolling product line, at the same time it is the main energy consumption equipment on iron and steel industry. It provides qualified billets for the hot-rolling process. So it is essential and benefit to research on optimal temperature setting and controlling of the reheating furnace to improve heating efficiency and reduce energy consumption for steel industry.The billet's reheating furnace is a typical complicated industry system with seriously lag-lead, multivariable, seriously coupled, time-variety, non-linearity, pure time delay and a lot of disturbance factor, and the billet's temperature can not be measured online, so the advanced computer control theory of repeating furnace is still far from mature, and there is little successful application example. There are still some tough problems which are not solved on reheating furnace's optimal control. (1) It is difficult to establish billet temperature model precisely. (2) As the objective function includes too more parameters, the traditional algorithm is not competent for real-time and precision, when to optimize the temperature setting.(3) Feedback of speed is too slow in the reheating system, which is with pure-time delay. Regarding on these problems, this paper gives some research achievements:Because of the complexity of reheating process and limitation of measuring equipment, the data is inevitable to be disturbed. We have the data to be preprocessed to denoise, to extraction the useful data.Aiming at the problems in optimal temperature setting, this paper established billet's two dimension temperature distribution model based on heat exchange theory. Considering reheating production targets, a new target function, which includes furnace's temperature setting value and billet's heating time, is proposed. And this paper adopts GA algorithm to get the optimum solution. The simulation results show that this method is better than traditional optimization algorithm on the precision and the stability.To solve the problem of adjusting furnace's temperature setting online, this paper gives a PID adjusting strategy which based on the deviation between billet's predicted value and wanted value. Taking the characteristics of the delay into account in large systems, a feed-forward compensation based dynamical optimal control method of set points of reheating furnace is proposed. The results show that the strategy we proposed is effective.