Research And Design Of Municipal Water Treatment Plant Automation System

Automation of water treatment process can make the complex production process operate achieve continuous safety, reduce cost and maintenance cost, and reduce the risks caused by human factors. Therefore, the advanced automation control is necessary for the process of water treatment. At the same time, in terms of the most significant index of water quality—turbidity, which is processed in the coagulant dosing,so the intelligent control of dosage also need further study.The research object of this thesis comes from waterworks automation system of a 100000 ton waterworks in Xi’an. First of all, consider analysis deep technical process and characteristics of the of water treatment of this project, on this basis, analysis of the control object Waterworks Automatic Control system. Based on above analysis, obtain the control object of automation controlling system. According to the requirements analysis of system, design distributed automatic control system of water treatment plant based on PLC, which is consisted of the central monitoring station and three PLC field control station and field instruments, different levels communicate through different ways. The hardware used Control Logix series programmable logic controller of Rockwell company, detection instruments of E+H company and Hach company and so on, at the same time design the control flow chart of each control module of the system, complete building the automation control system of the whole waterworks.Coagulant dosing is a very important step of water treatment, it determines the most important indicators of water which is transformed from factory to users—turbidity, therefore, this paper mainly study the automatic dosage control. In terms of the characteristics of e dosing process, such as time delay, nonlinear, difficult to establish a precise mathematical model, which often cause incomplete purification, or excessive dosage and other issues, put forward 2 kinds of controlling algorithms which is based on PID control algorithm and fuzzy control algorithm based on rules and self-adjusting factor fuzzy control algorithm to control dosage, then simulation results show that self-adjusting factor fuzzy controller could obtain smaller overshoot and faster response speed than other controllers, so choose this method to control dosing.Compared with traditional water automation control system, this control System have improved substantially in the level of intelligent, achieve the purpose of optimization control and save cost, in small and medium-sized city waterworks automatic control system has a good application prospect.