基于PLC控制的城市污水处理系统的设计.doc

基于PLC控制的城市污水处理系统的设计 摘 要 随着城市的快速发展，环境问题显得日益重要。废水是破坏环境的一个主要的因素，目前中国污水处理自控系统相对落后，污水处理成本居高不下，污水厂排放的处理过的污水的水质不稳定，所以如何建立有效的自控系统，优化运行效果，减少运行费用，具有重要意义。 本文介绍了城市污水处理的基本工艺和流程，并通过研究设计一套基于PLC控制的污水处理系统。 文章首先介绍了PLC控制系统的硬件结构、工作原理以及设计PLC控制系统的基本原则和步骤，然后以SBR污水处理工艺为例，来说明PLC在污水处理过程中的应用。 先根据污水处理要求设计了设备的电气控制与自动控制线路，主要包括设备的启停、状态信号、故障信号和信号采集等。最后按照工艺要求设计PLC控制系统，其中包括PLC的选型、系统资源配置以及按照污水处理工艺编制PLC程序等。建立高度自动化污水处理厂，不仅可以加强整个系统的可靠性、准确性，还可以减少劳动强度，降低处理成本和节约能源。污水处理厂自动控制系统的建设将降低生产和维护成本，减轻生产及维护工人的劳动强度，并为生产工艺的进一步改进提供方便，具有很好的经济效益和社会效益。 关键词：污水处理，SBR，PLC Abstract With the rapid development of cities,theenvironmentbecomesmore and more important.Wastewater is one of the major factors that pollute the environment.The automatic controlling system of wastewater treatment in China is not very advanced.The cost of wastewater is high.The water qualities of the treated wastewater areunstable.So how to solve the problems is very significative to ourcountry. This text introduced basic craft and process of city wastewater treatment, and design 1 set according to the wastewater treatment system of PLC control through the research The article introduced a PLC control the hardware structure, work principle of the system and design PLC a control system first of basic principle and step, then with the SBR wastewater treatment craft for example, explain that the PLC is in the application in the wastewater treatment process. Designed the electricity control of equipments and automatically control circuit according to the wastewater treatment request first, mainly include the start and the stop of equipments, appearance signal, break down signal and signal to collect etc.. Finally request to design PLC control system according to the craft, include the choose of PLC type, system resources an allocation and draw up PLC procedure according to the wastewater treatment craft etc. among them. The establishment of high level automation on sewage treatment plant, not only may strengthen the system’s reliability, accuracy, bu