| In the field of industrial control, process automation requirements are becoming increasingly complex, added with the growing demands of integrated management and control from the factory, there’s an urgent need for an open and efficient communication network that has strong expansion capability to support the process control system. Industrial Ethernet has inherited the normal Ethernet with its high-speed transmission, low power consumption, easy installation and compatibility, etc. By means of Ethernet switching and full-duplex technology, Industrial Ethernet can achieve a seamless connection from the device layer to the information layer, and gradually be applied to the field of industrial control.In this paper, the EtherNet/Ip Industrial Ethernet communication structure model and the network protocol were deeply analysed on the background of the urea-SNCR(Selective Non-Catalytic Reduction) flue gas denitrification project of a plant. Combined with the denitrification process, the SNCR Flue Gas Denitrification Control System was designed on the basis of EtherNet/Ip Industrial Ethernet. Under the Industrial Ethernet communication framework, the whole control system was divided into three layers:information layer, control layer, device layer. In order to facilitate access to communication networks much more intelligent devices with Ethernet communication interface were used in device layer, the other devices were accessed to the controller through a DeviceNet network. In the control layer, the CompactLogix control platform from Rockwell Automation was used. The control program was divided into modular and the appropriate program design process was proposed. The programs of urea solution preparation process, real-time dilution process, boiler-front injection process and their constraints were designed through programming software. The monitoring and control system for the upper computer, developed by Factory Talk View SE from the Rockwell Automation, establish the communication connection between information layer and the control networks and make the operators easily to monitoring and control the entire denitrification process.In order to improve the safety and reliability of the denitrification system, the redundancy design of the communication networks and some devices was made. In the running process of the system, since the conventional PID controller has no effective control for the flow of urea solution, the paper improved the PID controller with BP neural network. The paper designed and used the adaptive PID controller based on BP neural network, the simulation results show that the control algorithm works well.After a period of operation, it proves that the denitrification control system is running stable, safe and reliable. The control accuracy and denitrification efficiency can meet the requirements very well, it also has room for improvement, at the same time, the control system has a certain upgrade ability and scalability. The successful running of the flue gas denitrification control system proves that using EtherNet/Ip Industrial Ethernet as the control system communication network is a perfect application. It has the application and promotion of higher value. |
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