The Application Of DCS In Sewage Treatment Automatic Control System

With the fast development of China's economy, the phenomenon of more and more serious water pollution impacted greatly in people's life, so that the sustainable development strategy and modern enterprise in China is facing enormous challenges. Recently, public demand for more technology in sewage treatment has risen sharply in China, prompted by attention of water protecting project. As one of the pillars of national economy, the oil refinery not only consumes large quantities of water, but also potentially being a point source of water pollution in the communities. Although in recent years, the level of sewage treatment systems in China has greatly improved, but the automation level and processing power of the system are still low when compared with foreign advanced technology. The technology not only wastes water resources, pollution of the environment, but also seriously influence the improvement of enterprise's economic efficiency.In this study, based on a systematical study of sewage treatment plants of an oil refinery in China, according to the actual wastewater treatment processes and control requirements, a control system for sewage treatments was designed using Distributed Control System (DCS), Programmable Logic Controller (PLC) and PROFIBUS communication protocols.Based on a systematical design, the central controls was employed in a system of ZheJiang JX-300XP DCS. This project successfully setup configurations of both hardware and software of JX-300XP system. Three-phase separator and Integration devices for sewage treatments, controlled by Siemens S7-300 PLC systems, were communicated with central DCS systems using PROFIBUS-DP communication protocols. Complex communication problems in automation control among heterogeneous systems, between DCS (JX-300XP) and PLC (S7-300) system, were solved and documented in this project.The design of the DCS system for sewage treatment was successfully employed in the oil refinery. The control system has significantly improved the efficiency and accuracy of the sewage treatment system and reduced work loads of current workers by successfully implementing automatic data communication and monitoring remotely. After the debugging and actual running, the system operates satisfactorily.