| It plays an important role of asphalt agitated plant in highway construction. Asphalt agitated plant used currently is divided into batch and continuous type. It has many advantages of continuous asphalt agitated plant compared to batch type. However, volumetric method is used in the material measurement of traditional continuous asphalt agitated plant, and the measuring error is very large.It is researched Continuous Drum Asphalt Agitated Plant in the paper. And the control system included PLC control system and monitored control system is designed on the base of understanding its development, equipment structure and technical requirements. For the defect of traditional measuring method, it is advanced using ratio control to control the ratios of aggregate, powder and asphalt automatically, and mixing process PID algorithm is used.According to the control requirement, it is used Siemens S7-200PLC in the design. In the compiling environment STEP7-Micro/WIN4.0 SP6, the PLC software is designed and debugged, and the functions of the system are realized. It is used WinCC to realize monitored control system. Control order to PLC can be issued by PC, and various of field data can be passed to PC and displayed in PC to realize the real-time monitoring of production process by PLC. The Communication of WinCC and PLC can be realized by PPI protocol.Through the result of Matlab simulation, we can see it is effectively improved the accuracy of mixture and production quality due to the application of double closed loop ratio control and mixing process PID algorithm. It has great practical value. |
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