The Research Of Air Pressure Control To Foundry Cavity Liquid Level Control For Copper Continuous Casting Holding Furnace

Lever control of crystallizer is an important part during the continuous casting. The level fluctuation may lead to protective dregs and the impurities get into the copper water, which could affect the quality of the copper or even cause the copper water to leak and overflow, so the level must be controlled within a reasonable range. However the crystallizer level system has the characteristics of the non-linear and time variability, there are many unsure disturbing factors in this system so the precise mathematical model can not be proposed. The traditional control method could not be satisfying with the requirement of higher automation and quality. The thesis mainly researches the application of nitrogen control system to level control for copper continuous casting holding furnace, establish the equation of state of nitrogen at high temperatures and the thermodynamic properties of nitrogen in polytropic process, the thesis has taken research on Fuzzy-PID control algorithm based on revised genetic algorithm, which is applied on level control of copper continuous casting holding furnace, it is better to get good performance and improving safety and economy of holding furnace,The main content of this thesis:In chapter 1, the characteristic and actuality of this thesis is presented, the development of traditional PID control theory and fuzzy control theory is reviewed . Lastly, the main research subjects are presented,In chapter 2, copper continuous casting holding furnace is introduced. Holding furnace's structure and air pressure control theory are expounded, provided the instruction theoretically for the next step product the level control of holding furnace.In chapter 3, through the thermodynamic properties of nitrogen in holding furnace analysis, establish the equation of state of nitrogen at high temperatures, which is based on Van der waals equation. Through the thermodynamic properties of nitrogen in polytropic process research, the pressure from initial pressure to predetermined pressure of 99%(inflatable process)or1.01%(put gas process) and isobaric process are simplified, provided theoretical basis for level control of holding furnace.In chapter 4, the thesis research on level control of holding furnace by fuzzy control and simulation. Compared with the traditional PID control, it is better to get good performance and improving safety and economy of holding furnace.At the end, some conclusions in this thesis are summarized and the future research proposals are suggested.