Design And Development Of The Intelligent Control System Of Decomposing Furnace In Cement Production Process

The function of the decomposing furnace is to pre-decompose the carbonate in raw material, ensuring the decomposition rate over the technical index before entering into the rotary kiln. Decomposition rate is the main technical index of the decomposing furnace. And the decomposing rate of raw material is directly affected by the temperature of decomposing furnace, by which the sinter process stabilization, the final production quality and the equipment operation efficiency and energy consumption are also restricted. Decomposing furnace is connected to rotary kiln and pre-heater directly, so problems of severe equipment coupling, furnace combustion, heat transfer, decomposition complexity, nondeterministic disturbances, and strong nonlinearities exist in the temperature control process. Since the accurate mathematical model is un-established, the conventional control strategy cannot reach automatic control. Most of the cement decomposing furnace is still under manual control with human operators. As a result, the operator’s workload is high and the product quality is hard to be kept consistent. What is worse, the kiln running rate and yield remain low and the energy consumption remains high. Therefore, it is significant to research automatic control technology for the decomposing furnace to stabilize the production quality and improve the yield and production efficiency.This dissertation has made research on the design and development of the intelligent control system of decomposing furnace, supported by the National Hi-tech863/CIMS. The research also takes as its background the1500tons/day new dry cement production line by automatic project of Jiu-STEEL Group HongDa Building Material Co., Ltd. The main work of this paper is as follows:(1) The intelligent control strategy and control method of the intelligent control of decomposing furnace temperature are studied. In this paper, the intelligent control strategy of the decomposing furnace temperature and the strategy of steady flow silo weight control are proposed. The intelligent control strategy of the decomposing furnace aims to deal with the characteristics of decomposing furnace process, the online detection difficulty of decomposition rate index, the difficulty of direct closed-loop controlling on the quality index. Thus the intelligent control strategy of decomposing furnace process proposes the combination of advanced control methods which are fuzzy control, feed-forward control, PI control and rule control and it designs the controller, which includes a fuzzy supervisory controller, a feed-forward controller, abnormal condition controller and the switching mechanism of decomposing furnace. The simulation control on the temperature of decomposing furnace has been achieved; Because of the effect of the fluctuate of steady flow silo weight on raw material supply process, the steady flow silo weight control strategy proposes that PI controller or rule controller is selected when the working conditions are different, the purpose of which is to control the steady flow silo weight and reduce the effect of fluctuate of steady flow silo weight on the raw material supply process. In order to ensure the equipment running steadily and continuously and to keep the safety of workers, we achieve the single equipment and process equipment interlocking chain.(2) Based on the above control strategy and control methods, the structure and function of the control system have been designed and cultivated. The structure of control system is divided into process control level and process running monitor and management level. The process control level includes loop control and logical control, which are used to realize the control function of production process. It functions as logic chain, temperature automatic control of decomposing furnace and weight automatic control of steady flow silo weight. The function of the process of running monitor and management level mainly includes operation interface, user login, data archiving, history curves and alarm information, etc.(3) The industrial application and industrial experiment results of decomposing furnace control system are analyzed. German Siemens S-400control system is adopted as the system platforms of this project and the control strategy and control methods mentioned above have been applied to the first line of cement clinker production built in Jiu-STEEL Group HongDa Building Material Co., Ltd.