The Design And Research Of Monitoring System For PU Reactor Based On DCS

The physical characteristics of PU(polyurethane) are varied, and different proportion of raw materials will produce different chemical reaction, which bring different physical properties for PU. Nowadays, artificial charging and manual control mode are used in most of PU production enterprises, whose products quality is not good and the production safety can not be guaranteed. Therefore, an automatic control mode for the production process of PU reactor is to be researched based on designing a DCS monitoring system for a production workshop of a company in this paper.The purpose of this paper is to research on the automatic control mode for the production process of PU reactor. At first, by the analysis of the productive technology and control requirements of the PU reactor and the comparison of several current mainstream control systems, a DCS monitoring system is chosen, in which Siemens S7-300PLC and WinCC is used as the core. Then, the control cabinet is designed and software is developed:Main motor driving circuit of reactor, control circuit of feeding pump and valve, alarm circuit, and weighing circuit which is very important are included in the control cabinet; the program development of hypogenous machine software STEP7and the monitor screen configuration of PC software WinCC as well as the industrial Ethernet communication between STEP7and WinCC are included in software development.Automatic control method and manual control method are both included in DCS monitoring system of this paper. The automatic control mode is used at normal production process in which less people are on duty; however, the manual control can be quickly switched to when the production process problems arise, so that the convenient and effective maintenance and debugging can be realized.The DCS monitoring system of PU reactor, including many features which come out in front in the domestic PU reactor production control system and have a certain reference value such as the redundant system, valve&pump linkage, weighing circuit, manual/automatic switching control and so on, is designed rigorously and function reliable. The system has been stable running in the factory for nearly one year after design, installation and commissioning. During this period, the stability and control effect of the system is good which achieve the expected control requirements, so that the correctness of the design idea and scheme in this paper is verified. The method in this paper provides certain theory significance and realistic basis for the application and development of DCS in PU production control field.