| Because the original production line of Baotou Iron and Steel Group has a single variety of steelmaking,the quality of steel is not high,and the working environment of steelmaking workshop is bad,the equipment is bulky,which has a certain working risk.In order to improve the quality of steel and change the product structure,a new double-station RH refining furnace has been built in Baotou Iron and Steel Group Rare Earth Steel Plant.The design of its automatic control system can improve the working environment and improve the working efficiency,which has important practical significance in engineering.This new RH refining furnace can process 1 million tons of molten steel annually,which mainly meets the requirements of rare earth steel sheet factory for producing high quality automobile sheet and high performance sheet metal.On the basis of expounding the present situation and development trend of automatic control system for vacuum refining,this paper analyses the main production equipment of RH refining furnace and the process flow of RH vacuum treatment at Baotou Iron and Steel Co.,Ltd.It also analyses the performance,parameters and action sequence of ladle car system,vacuum pump system,slag breaker system,wire feeding argon blowing system,oxygen lance system and vacuum tank system of vacuum treatment device.The technical principles of PLC control technology,fieldbus technology and frequency conversion speed regulation technology are described.Because in RH refining furnace system,oxygen lance system and vacuum tank system are the most important links in the whole system,so the design mainly includes the following aspects:(1)Introduce the background of this topic and analyze the research status at home and abroad,the development trend of RH refining furnace in China,and list the main research work of this topic.(2)On the basis of investigating the production process of RH refining furnace on the spot and understanding the working principle,performance index and control requirements of the process equipment,this paper gives a general explanation of each system of RHrefining furnace,and mainly designs the control scheme for the oxygen lance system and the vacuum tank system.(3)The hardware design of the system is completed according to the characteristics of field control objects and electrical design specifications.It mainly includes the design of control system network scheme,mainly using three-tier industrial network to realize automatic control system;variable statistics,field bus selection and instrument and frequency converter selection,including the control wiring and main circuit design of PLC master station and slave station.(4)For the control design of oxygen lance system and vacuum tank system of RH refining furnace,PID cascade control is adopted,and the vacuum tank system of RH refining furnace is optimized.(5)Software design and monitoring system design of RH refining furnace control system,real-time dynamic monitoring and centralized operation of RH refining furnace control system are realized by monitoring software WinCC. |
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