Design And Development Of Ball Mill Intelligent Optimal Control Software Of Alumina Dissolving Process

There are three methods in the production of alumina, which are the sinter, Bayer and combined method. Owing to the low-grade A/S of the aluminum mine, the sinter and combined method are widely adopted in our country. In the procedure of the sintering, the function of dissolving process is to make the Al2O3 and Na2O dissolved from the clinker fired by rolling kiln as much as possible, in order to guarantee the concentration of sodium aluminate and sodium carbonate in the target range.The alumina dissolving process is the bond of the two producing process of wet and dry method, and it is also the most important part of economic index in the sinter method. The alumina dissolving process has complicated characteristics of nonlinearity, long time-delay, slow time-varying and so many key process parameters which can not be measured online, so it is dramatically significant and difficult to study the control and the optimization techniques of the process.Supported by National 863 Plan subject "Large-Scale Ball Mill Intelligent Control System" (No.2007AA041405), the ball mill intelligent optimal control software of alumina dissolving process is designed and developed, and the developed software has been tested to prove its feasibility and effectiveness. The contents of this paper are summarized as followed:(1)The ball mill intelligent optimal control methods of the alumina dissolving process are researched, and the intelligent optimal control strategy, which consists of intelligent optimal setting method and basic loop control method, is proposed. The intelligent optimal setting method consists of the preset model based on CBR and the feedback compensation model based on experts rules.(2) Combined with the characteristics and control requirement of the alumina dissolving process, this paper designs the structure and functions of the ball mill intelligent optimal control software of the alumina dissolving process. The function of intelligent setting software is to optimize the flow set points of the basic loops based on the working conditions, in order to guarantee the concentration of sodium aluminate and sodium carbonate in the target range; The process monitoring software is mainly to monitor the states of the production process; The function of basic loop control software is mainly to control the production devices,such as the start/stop of devices, interlock function and loop control.(3)In the project of the alumina dissolving process, the basic loop control software is developed based on the Control Builder platform, the process monitoring software is developed based on the HMIWeb Display Builder platform,and the intelligent optimal setting software is developed based on Visual Basic 6.0 platform. The development of intelligent optimal setting software includes:the development of OPC client based on automation interface, the development of case base using the ADO component and Access software, and the development of interfaces of the intelligent optimal setting software.(4) The subscription and asynchronous communication functions of OPC are tested to realize the data exchange between the intelligent optimal setting software and the PKS computer control system;the function of the case base of the preset module is tested to realize the addition, revision and deletion of a case;the preset module, feedback compensation module and setpoint download module are tested to successfully calculate the preset values, feedback compensation values and flow setpoints respectively. The tests of the functions of OPC communication, the case base and software modules prove feasibility and effectiveness of the developed software.