The Design And Research Of Converter's Bottom Blowing Control System

At present Convertersteelmaking-refined and continuous casting has been used in many steel enterprises.The main raw material of converter steel-making is molten steel,scrap steel and ferroalloy.Without external energy,steel-making is accomplished by the physical and chemical reactions between the molten steel and the heat of the molten steel.In the production process of converter steel-making,using the technology of bottom blowing is to improve insufficient mixing power of top-blowing-converter.The bottom blowing technology becomes a crucial procedure of converter because of its good metallurgical resultsforinstance highly stirring,distributing ingredient and temperature,increasing the rate ofchemical reactions,removing inclusions and soon.Therefore,it is very important to study the precise control of nitrogen and argon flow in the bottom blowing system.Because nitrogen has certain influence on the quality of molten steel,it can be switched to argon at certain stage in steelmaking process,in consideration of two factors of economy and quality,nitrogen and argon are controlled by the automatic system,and the corresponding gases(nitrogen and argon)are changed in different smelting stages,so as to achieve the best performance.Thethesisresearches the flow control of bottom blowingnitrogen and argon based on PGCSST's 80 t steel-making converter.First,the process and structure of the bottom blowing system are studied,and then establish the system model based on the classical PID control algorithm.The author designa converter bottom blowing control system based on the established system control model.Converter bottom blowing control system adopts SIEMENS S7-400 PLC,and combining the WinCC configuration software to acquire pipeline flow,pressure,control valve opening and other field instrumentation data for real-time monitoring,tracking the bottom blowing process information,smelting cycle,and according to theinterlock setting to start or stop the device,setting the valve opening.Converter bottom blowing control system can also generatealarm records of important parameters and real-time/historical curve.Based on the analysis of converter bottom blowing control system,the model of converter bottom blowing system is established.The PID control algorithm is used to obtain the transfer function of the bottom blowing system,and the simulation experiment and field debugging of the bottom blowing process are carried out by the combination of SIEMENS and PLCSIM software.The experiment shows that this control system can through the controller output to the valve actuator,dynamic regulation of air flow size,so that it has good dynamic performance and eliminate steady-state error,meet the requirements of the production process,and have high control precision.