Grate - Kiln Computer Control System Design

In view of the situation that the measure and control system for pellet sintering of grate-kiln is relatively backward, this paper discusses a computer control system based on Industrial Ethernet, which could be used for parameter detect, parameter control and process control. This research can provide pellet plant the best ratio of the raw materials and have the vital practical significance to the pellet production.After analysising the grate-kiln sintering technology characteristics, in this paper a improved grate structure program has been proposed, which reducts the hardware investment and improves the efficiency. According to the analysis of system functions, this paper studied a two-level control system based on Industrial Computer, Intelligent Instruments and Programmable Logic Controller. The application of Intelligent Instruments improves the system's control precision and reliability. The monitoring software is designed based on Delphi 7.0, and realized online monitoring of the detect process. To meet the requirements of real-time and reliability, the system used Industrial Ethernet to complete the communication tasks between Industrial Computer, Intelligent Instruments and Programmable Logic Controller.The roasting in the kiln is the most important stage during the process of the pellet sintering, so the control of the kiln's temperature is the key factor. According to the features of the kiln's temperature such as nonlinearity, large time-delay, time-varying, this paper applied the kiln'temperature fuzzy adaptive PID and Smith composite algorithm, as well as used the relay-identification method to identify the temperature control system of the kiln under different tempereture according to the analysis result of the heat balance and the characteristics of Smith predictor. In order to reduce the compensation error which results from the unmatched model, the method is used in the paper, that using the discrete model to approximate the continuous change of the actual model. The main controller is the SIEMENS S7-200 PLC, and in conjunction with the monitoring software, the control strategy has been achieved by the ladder language.Simulink in the Matlab was used to do the strategy simulation,and the result proved the control strategy is feasible. The grate-kiln computer control system has been put into use and runs well.