The Alteration Of Control System For Reheat Furnace In Strip Plant

The hardware of computer control system in strip plant is old, and it does not work well, so takes the SIMATIC S7-400PLC instead of MITSUBISHI PLC which is used before alteration and buy some new facilities and measuring instrument, to make the control of reheating furnace reach the advanced level. Because of the advance of hardware, the software also must be improved to adapt the hardware. By the alteration of hardware to improve the control level of equipment, taking the advanced method to make the temperature of reheating furnace in the right range. It is important that making sure the quality is good; enhancing the quality of product, reducing the energy consumption and burning loss of steel.Based on the computed result of math module of reheating furnace's reheating process, this paper have a study on method of expert control, expert control is a control method which is forming about ten years, it based on controlled object and all kinds of control method, and apply those knowledge in aptitude, making the control process work better; using expert control in the reheating process of reheating furnace will have a better result than traditional method. The temperature control of reheating, the press control of coal gas and air, the protection of heat exchanger by the way of expert control have a better result than traditional method, especially when the pressure of coal gas is changing.The paper uses method expert control, designed expert controller based S7-400PLC, it contain program modules of the acquisition and process of data, of the optimization of air-fuel ratio, of the temperature control of reheating furnace's each section ,of the pressure control, of the protection of heat exchanger, of the performing of valve, of the controlled variable which learning by itself, and so on; based on information which is gathered form reheating furnace, after computing, the expert controller sent a control conclusion, to make the temperature of reheating furnace in the right range, the flux of air and coal gas is stabilization, and the heat exchanger working smoothly, complete the task of reheating control well. And have developed a monitoring system in upper computer by SIMATIC WinCC, it completes the display of Real-time parameter, the setup of process parameter, the display of dynamic curve, and so on.The result of debugging indicate the programme is right, the method of expert control can complete the temperature control of reheating, the press control of coal gas and air, the protection of heat exchanger; also prove the selection of expert control is right, the method of expert control basing on PLC is feasible, meeting the control of reheating furnace completely.