中文摘要：

对化工厂污水处理的工艺流程给予了详细的介绍，并据此提出了应用OMR（）NPLC典型的三层网络架构（管理层的以太网（Ethernet）、控制层的控制器网（ControllerLink）和设备层的Devicenet网）来构建污水处理厂集散控制系统；根据污水处理过程各个部分的控制目标和执行机构的特点，给出了污水处理各个部分的下位机PLC控制程序流程，进而对下位机控制程序进行了详细的设计；在下位机的设计中，重点研究了污水处理过程中SBR工艺中溶解氧浓度的PID控制算法；设计并开发了基于Citect6．0组态软件的上位机监控界面，实现了对现场设备运行参数的在线监控和故障报警信息的实时显示；上位机监控界面主要包括系统工艺流程界砸，各个部分的控制界面，报警界面，趋势界面和PID控制界面等；整个污水处理计算机控制系统投入持续运行一年，日处理污水达到了120001230／d，最终实现了环保和经济效益的双赢局面。

英文摘要：

This paper introduces in detail the process flow of wastewater disposal. , and designs the distributive control system in wastewater disposal plant based on 3--tiered architecture （Ethernet, Controller Link, Devicenet） of OMRON PLC. According to control objective of each part and the features of actuator, this paper designs PLC program of each part of wastewater disposal process and emphasi- zes on studying PID control algorithm of dissolved oxygen in SBR craft. Upon the completion of the PLC control task, we design the monitor pictures based on citect6.0 which is software development platform. Through the monitor pictures we could monitor realtime parameter and get the realtime information. Monitor pictures includes general flow picture, control pictures of each part, trend pictures, alarm pictures and PID control picture. The whole DCS have been running for one year after production. It has a capacity to treat wastewater up to 12000 m3/ d, and ultimately realized the win--win situation of environmental protection and economic benefits.