Intelligent Optimization Control In Furnace Production Process

Heating slab process is an important part in steel rolling production process, which not only affects directly product performance, but also influences product cost and safety of production equipment in production process. So it is very important to steel makers by using advanced control means.At present, most of furnace is pusher-type or walking beam type, the main content of furnace control system is on the premise of that slab met the demands of rolling can be produced in the furnace, to improve heating efficiency of slab, to save energy consumption, to reduce oxidation burning loss and decarburization of slab surface, and to prolong service life of equipment. But furnace is a typical complex industry controlled object, in which all kinds of chemical, thermodynamic and physical process are contained. Furnace system has characteristics of pure hysteresis, multivariable, compact coupling, nonlinear and big inertia. It is very difficult to make an accurate mathematical model. The temperature in furnace can not be measured directly because of much disturbance outside. Heating process is constrained by many kinds of production technology factor. So it is difficult to reach a satisfied controlled effect by applying classical optimization control method. Now, most production of furnace only depends on operators by experience to control base loop set-point value. When operating condition is changed, under heating or overheating will occur, which not only wastes resource, but also decreases production quality. According to the above things, main work is done in the paper as follows.(1) A heating process was set. Based on the metallography principle, analyzed the metal heating temperature, heating speed and heating schedule, combined with the Heavy Plate Plant of Anshan Iron and Steel production situation, classified the reheating billet, each type of steel's reheating temperature and heating rate in the furnace are set.(2) Designed an automatic control strategy of reheating furnace. According to the characteristics of control system and the production condition of reheating furnace, the control system of furnace temperature, gas and air flow rate and pressure of furnace were respectively designed.(3) The optimization of the heating furnace temperature was set in this paper. In order to realize minimum energy consumption, minimum billet oxidation burning loss, minimum billet temperature difference between billet surface and center, the optimal target function was established, the function was solved by optimization algorithm. In the last we got the optimal temperature distribution curve. According to the furnace operators'experience and knowledge, the optimal furnace temperature distribution was modified, to meet the needs of practical production process.(4) Using high thermo stability temperature testing device, we actually measured the on-line temperature of Q345A steel in the reheating process, to check the running state of automatic control strategy. Meanwhile, the steel temperature changing curve was obtained, which could provide dependable data for the optimizing of reheating schedule.