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河南理工大学毕业设计（论文）I摘要本文设计了一种基于PLC控制的污水处理系统，PLC具有通用性良好、可靠性较高、编程控制快捷便利、安装较为简单等优点。长期以来，在推进城市发展的进程中，由于对基础设施建设重视不够、投入不足，污水直接排入城市水系及相关流域造成江河湖泊水质和地下水污染，城市水污染问题日益突出。加上我国是一个严重缺水的国家，水资源的匮乏和污染已严重的影响了人民的日常生活，影响了全国的经济建设和发展。中国污水处理控制系统相对落后，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，因此建立有效的自动控制系统对降低工业污水治理成本、改善生态、建立可持续发展社会、保持我国经济高速发展具有重要意义。本文介绍了污水厂处理污水的基本工艺和流程，并设计了一套基于PLC控制的污水处理系统。文章综合当前常用的污水处理工艺，介绍了本设计的污水治理方法，PLC控制器优越的可靠性、抗干扰性以及方便灵活的编程等特点，讲解了PLC控制系统硬件结构、工作原理、PLC的选型、PLC资源配置、软件设计等部分，来说明PLC在污水处理系统中的应用。根据污水处理要求设计了设备的电器控制与自动控制线路，其中包括设备的启停、状态信号和故障信号采集与判断等，并编制PLC控制系统程序。关键词：污水处理PLC工艺流程河南理工大学毕业设计（论文）IIAbstractAtpresent,themajorityofoursewagetreatmentcontrolsystemautomationlevelisnothigh,lowsecurity,mismanagement,efficiencyisgenerallylowerthantheworldstandard.Sewagetreatmentsystemintheaerationprocesscontrol,datacommunicationsandmonitoringandmanagementarethemainissuesthatneedtoberesolved.Chinasewagetreatmentautomaticcontrolsystemisrelativelybackward,thehighcostofsewagetreatment,sewageplant'streatedeffluentqualityofinstability,howtoestablisheffectiveautomaticcontrolsystemtooptimizetheoperatingresults,andreduceoperatingcostsisofgreatsignificance.Thispaperintroducesthebasictechniquesandprocessesofplantsewagetreatment,andasewagetreatmentsystembasedonPLCcontrolstudydesign.ThearticlefirstintroducesthePLC-basedsewagetreatmentprocessandrelatedprocesscontrolsystem,controlsystemhardwarearchitectureanddesign,operatingprinciplesandthebasicprinciplesofthedesignofPLCcontrolsystemandthestepstoillustratetheapplicationofPLCinthesewagetreatmentprocess.Firstdesignofelectricalcontrolandautomaticcontrolcircuitaccordingtothesewagetreatmentrequirements,includingstartandstopequipment,statussignalfaultsignal,andsignalacquisition,thefinaldesignofPLCcontrolsysteminaccordancewiththeprocessrequirements,includingtheselectionofthePLC,thesystemallocationofresources,aswellasthepreparationofthePLCprograminaccordancewiththesewagetreatmentprocess.Keywords:sewagetreatmentthePLCprocess河南理工大学毕业设计（论文）III目录1绪论......................................................................................................................................11.1引言...................................................................................................................................11.2污水处理的国内外现状...................................................................................................21.3课题主要设计的内容.......................................................................................................32污水处理控制系统总体介绍................................................................................................42.1城市污水处理基本概念...................................................................................................42.2常用的污水处理工艺......................................................................................................52.3本设计系统污水处理工艺及描述...................................................................................82.4污水处理系统控制形式...................................................................................................92.5污水处理系统的功能要求.............................................................................................102.5.1信号输入..................................................................................................................102.5.2控制输出信号..........................................................................................................113硬件系统配置......................................................................................................................123.1主要组成部分.................................................................................................................123.2电气控制系统.................................................................................................................133.3污水处理系统的工作原理.............................................................................................143.3.1控制系统总体框图..................................................................................................143.3.2工作过程..................................................................................................................143.3.3污水处理系统主电路设计......................................................................................153.4PLC的选型...............................................................................................................163.4.1PLC的选择.........................................................................................................163.4.2S7-200PLC概述.....................................................................................................163.5PLC的I/O资源配置.....................................................................................................173.5.1数字量输入部分......................................................................................................173.5.2数字量输出部分......................................................................................................173.5.3模拟量输入部分........................................................................................