Research On On-line Dynamic Optimization Methods Of Furnace Temperature In Walking Beam Reheating Furnace With Operating Mode's Switch

Reheating furnace is the important equipment in the steel rolling production process. The production of the reheating furnace is a process of the rise of the billet temperature, which can be described by the nonlinear partial differential equation of heat conduction. The main purpose of reheating furnace production is to make the slab temperature distribution meet with the requirements of the rolling process, and achieve the fewest stock scale loss and energy consumption, accordingly to improve product quality and reduce production costs. From the view of the global optimization in production process, the optimization methods of the reheating furnace temperature are to give a optimization temperature of the different part in reheating furnace satisfying the constrains in reheating furnace production process.The initial temperature of the billets, the types and specifications of the steels, rolling rhythm production conditions are often changed during the reheating furnace production process, which makes the product process existing strong uncertainty and dynamic characteristic. In this case, we must adjust the reheating furnace temperature to make the billets temperature distribution meet with the requirements of the rolling process and improve product quality, reduce energy consumption. The existing literature generally discuss about the problem of the optimization and control of the reheating furnace under the special operating mode while the research on the dynamic optimization methods of furnace temperature in reheating furnace with operating mode's switch is less. However the setting value of the furnace temperature is based on the artificial experience at the production site, which is difficult to make the control system achieve the optimal adjustment and result in the problem of the production efficiency and product quality.Aiming at the problems of the on-line dynamic optimization of furnace temperature in reheating furnace with operating mode's switch, this paper gives some research achievements:Firstly, this paper analyzes and describes the production process of the reheating furnace, proposes the problems of the on-line dynamic optimization of furnace temperature in reheating furnace with operating mode's switch, and then raises the solving strategies to solve these problems based on the idea of rolling optimization. Aiming at the problems of the unmeasured of the slab's temperature in the reheating furnace and the requirements in the time of the slab temperature calculation under on-line optimization, this paper establishes the billet's temperature distribution model based on heat exchange theory.Then, this paper establishes the index model and the constraints model which are based on the reheating furnace's temperature optimize problems under the steady state work conditions to obtain the optimal curve of the billet's temperature rising. With the optimal curve of the billet's temperature rising, this test builds the model of the on-line dynamic optimization of the furnace temperature in reheating furnace with operating mode's switch, and gets the solution under the idea of rolling optimization.Finally, this paper puts forward the model of the reheating furnace's temperature and establishes the semi-physical experimental system of the reheating furnace based on the actual PLC controller. Then, verifying the effectiveness of the on-line dynamic optimization methods of furnace temperature in the reheating furnace with operating mode's switch.