Design Of The Circulatory Suspension Semi-Dry Type FGD Monitored Control System Based On PLC

Although China has current positive progress in environmental protection, environmental situation is still grim. So many power plants have produced lots of FGD removal devices, for the purpose to positively respond to national saving and environmental protection policies. However, for the FGD removal system, the control level is relatively low. This paper mainly designs a set of FGD monitored system for the power limited liability company, including the hardware selection and the software programming, systematically elaborating the monitored system's main control functions.Firstly, this paper studies the current development of FGD control system at home and abroad, mainly analyzing the scope and application examples of the Semi-dry FGD process. By analyzing the basic process of the circulatory suspension semi-dry type FGD, the overall analysis of the control system is respectively carried out from the hardware to the software. In terms of the hardware, the equipment selection and overall configuration are mainly designed, and in terms of the software, the realization of various functions is analyzed and the main program control process is designed.Secondly, the specific nature of controlled objects in each control loop is analyzed, and the cascade control system is applied to the each control loop. Then the traditional PID control algorithm is improved, and the incomplete differential PID control algorithm is applied to the lime slurry and cooling water flow control systems. And then, the simulation software Lab VIEW is used to analyze incomplete differential PID control algorithm simulation, mainly the effect in flow control. Through observing the system waveform, the system stability time and all parameters'setting are determined. After all the analysis, PLC ladder program of the algorithm is prepared by using the programming software STEP 7.Thirdly, the configuration software is developed for the PC. By analyzing design requirements of the FGD control system, the PC monitored interface is designed by using the configuration software Fame View to achieving several functions, including the creation of data tables by using the database functionality and the alarm information inquiry table, in order to providing clear reports to operators for analyzing and solving practical problems.Finally, the communication between IPC and PLC, and the communication between PLC and the micro master are set up respectively. By analyzing the communication protocol of the MPI network and PROFIBUS DP network, real-time monitored system is achieved.Through designing the circulatory suspension semi-dry type FGD monitored control system, the functions of various parts are realized theoretically and the foundation of practical applications is laid for the future.