The Alteration Of Control System For Reheat Furnace In Hot Strip Continuous Rolling And Optimum Of Reheat Technology

Reheating furnace is very important heating equipment in steel rolling plant, which is crucial to the rolling temperature. It consumes most of energy during the rolling process.The technology requirements of the furnace is to heat slabs to the desired temperature distribution for rolling process, and diminish the energy consumption of the reheating furnace and burning loss of the slab as much as possible. But most plants rise the output temperature of the slab deliberately in order to guarantee the temperature distribution of the slab, ignoring the optimization and energy target of the furnace and oxidation target of the slab in practical production. So improving the control level of the facilities, optimizing the reheating curve of the slab to reduce the energy consumption are crucial to increase the production, improve the quality of the products, and minimize the consumption of the fuel and the materials burning loss as well.The thesis consists of PLC upgrade alteration of walking beam furnace and optimizing the heating curse of the slab, which were carried out on control system of the heating furnace in the first hot strip continuous mills, Wuhan Iron & Steel Company. In order to improve the control level and increase online supervisory function of the walking beam running state, the first hot strip mills required to upgrade the hydraulic control system with S7-PLC control system without interrupting normal production of the original S5-PLC control system. The thesis elaborates the PLC program configuration and realization of the main functions, the communication ways between SIEMENS S5-PLC and S7-PLC series, mainly introduces the basic principles of FMS-Profibus communicating network, analyzes the task and realization of programming and configuration of S5 and S7, and gives the resolving scheme to existed problems. Simultaneously communication system of SIEMENS PLC was designed and successfully put into the production control in the plant.At the same time, the strained conditions of mathematics model were studied in the thesis by combining the reheating principles and running characters of the upgraded walking beam of the furnace. Then the heat curve of the slab with constrained condition of heating and rolling processing was optimized by the complex optimal method with aim function of minimum of energy consumption. The results of the optimization in this thesis improved the temperature control model obtained by congressional method, which provided basic guarantees for the productivity efficiency, good microstructure and quality of the hot strips.