Design And Development Of Control System Software For Red Mud Separation And Washing Process In Alumina Production

The red mud separation and washing process is one of the key processes in the production of bayer alumina.Its function is to achieve the separation of red mud and sodium aluminate solution.The process of red mud separation and washing is complicated,the process is long,and there are many equipments,and it is difficult to realize the automatic operation of the whole process.Key circuits such as the thick layer of thick machine affect the effect of separation and washing.This process has the comprehensive complexity of large inertia,nonlinearity,and strong interference.It is under manual control by operators based on experience,which leads to washing efficiency and sodium aluminate.The quality of the solution is reduced.Therefore,the realization of automatic control of red mud separation washing process is the key to ensure the separation washing target.In view of the above problems,this paper developed a red mud separation and washing process control system software for alumina production based on a domestic alumina project.The main work of this article is as follows:(1)Aiming at the characteristics of strong nonlinearity,great delay and strong interference in the height of the thickener mud layer in the red mud separation and washing process,the mathematical model between the height of the thickener mud layer and the flow rate and the concentration of the bottom flow in the red mud separation and washing process was established based on the solid flux theory.Based on the analysis of the characteristics of the model,in view of the difficulty that conventional cascade control is difficult to control the mud layer height of the thickener within the process specified range,an unmodeled dynamic compensation cascade PI control method based on the dense layer mud layer height is proposed.The inner loop of thickener underflow is controlled by PI,and the outer loop of mud height is controlled by PI based on unmodeled dynamic compensation.(2)According to the technical requirements of the red mud separation and washing process,the DCS control system is combined with the red mud separation and washing process,and the red mud separation and washing process control system software is designed,which is composed of loop control software,logic control software and process monitoring software.The loop control software realizes stable control of the mud layer height,underflow flow,overflow pipe liquid level,and tank temperature of the thickener.Logic control realizes start-stop control of thickener mixer motor,underflow pump,overflow pump and other single equipment and safety interlock control of upstream and downstream equipment.The process monitoring software monitors the data and equipment status of the red mud separation and washing process,and automatically alarms when an abnormality is found.(3)Based on the DCS control system platform,using configuration software tool Studio 5000 and modular programming ideas,the red mud separation and washing process logic control software module and loop control software module were developed.The logic control software module uses standard pins to achieve external interlocking conditions With flexible definition,the loop control software module implements the cascade loop control algorithm for thicker mud layer height and other conventional loop control algorithms proposed in this paper.The monitoring configuration software FactoryTalk View SE was used to develop a red mud separation and washing process monitoring software module based on the C/S architecture,realizing real-time monitoring of the red mud separation and washing process.(4)Combined with the semi-physical simulation system,the simulation software for the model of red mud separation and washing process was developed,and the cascade control software for the thicker mud layer height was developed to conduct simulation experiments.The software function test,system test and industrial field test were carried out for the logic control module and process monitoring module in the developed alumina red mud separation and washing process control system software.