Optimization And Improvement Of Automatic Control System For Aluminium Hydroxide Roasting

Aluminium hydroxide roasting is a quite important in alumina production process.Roasting quality directly determines the quality of the products.At present,the domestic aluminium hydroxide roasting usually adopts positive pressure and negative pressure circulating fluidized bed roasting roasting,In the roasting process,the temperature control system adopts single closed loop PID control mode.The control system control method is relatively simple and relatively simple and the lag of the control system is strong.The fluctuation of temperature is more severe,and the precision and stability of the system are poor.In this paper,the performance and advantages and disadvantages of three popular circulating fluidized bed roaster at home and abroad are introduced This paper focuses on the analysis and reconstruction of the temperature coupling and hysteresis of the temperature control system of the positive pressure circulating roaster in the company,On the basis of the original single loop PID regulation,the feed forward Decoupling module and temperature sub regulation module are added.The accuracy of the automatic control system is improved,and the hysteresis and the volatility of the PID regulator are reduced.The main research work of this paper is : The component and working flow of the circulating fluidized roasting system,and the influencing factors of alumina reduction pass rate is analyzed,According to the circular flow temperature coupled system and roasting furnace temperature lag.A cascade control is proposed to solve the problem.The feed forward compensation is used to solve the coupling problem of the temperature in the furnace,The combination of the optimum parameters of the process was found by orthogonal test,and the decoupling control model was designed And the experimental method has been used to obtain the mathematical expression of the feedforward compensation quantity of the fuel valve opening increment,The hardware system of circulating fluidized bed roasting control system is improved,In the roasting DCS system,a simple script program is compiled,and the program module is added into the PID module of DCS.Finally,through many experiments,it is verified that the feed forward decoupling of the roasting system can basically solve the influence of the temperature on the opening of the discharge valve The cascade control circuit can shorten the lag time of the furnace temperature,which is in full compliance with the design requirements Finally,the paper summarizes the research work,In the light of the problems existing in the research,this paper puts forward the further research direction,which lays the foundation for further research.