基于PLC的电厂化学水处理程控系统设计

摘要I基于PLC的电厂化学水处理程控系统设计摘要化学水处理控制系统是电厂中非常重要的一部分，自然水中含有大量对电厂设备有腐蚀性的成分，直接使用会对设备造成极大的破坏，因此必须经过严格的处理才能使用。本课题先分析了传统控制方式和现代控制方式的优缺点，然后分析自然水的成分及其对化学水处理的影响，再分析选择化学水处理工艺，并完成此次设计的系统硬件配置和软件设计。根据分析，本次设计选择的工艺为反渗透（RO）—混床工艺流程，选择双滤料过滤器、反渗透装置以及混床等为主体装置，进行了PLC输入/输出分配、外部接线图的设计及控制系统的流程图的设计，并用STEP7编译软件编制了控制系统的梯形图并转换为指令语句。该系统经过模拟调试，可有效实现过滤器的运行与反洗，反渗透的运行和混床的运行、反洗和再生功能。关键词工艺，PLC，梯形图，模拟调试攀枝花学院本科毕业设计（论文）ABSTRACTIIABSTRACTThesystemofchemicalwatertreatmentisanimportantauxiliarysystemofpowerplant，naturalwatercontainscorrosiveingredientsinalargenumberofpowerplantequipment.usingitdirectlycancauseagreatdamagetotheequipment,soitmusttobetreatedbeforeusingit.First，theprojectanalysesthequalityofnaturalwaterandtheinfluenceofimpurityonchemicalwatertreatment,andthenchoosesthechemicalwatertreatmenttechnicsofpowerplant.Onthebasis,itcompleteshardwareconfigurationandsoftwaredesignofchemicalwatertreatmentcontrolsystem.Accordingtotheanalysis,theprojectchoosesthecraftofreverseosmosis(RO)-mixedbed,usingdual-mediafilters,reverseosmosisdevicesandmixedbedsandsoon.AfterthedesignofPLCI/Oassignmentandtheexteriordiagramsandtheflowchartsofthecontrolsystem,itcompilersLadderDiagramofcontrolsystemwithSTEP7andtransformsitintodirectivestatements.Throughsimulativedebugging,Thissystemcanefficientlyrealizetheoperationandbackwashingoffilters,therunningofreverseosmosisandtheoperation,backwashingandregenerationofmixedbeds.KeywordsCraft,PLC,Ladderdiagram,Simulationdebugging攀枝花学院本科毕业设计（论文）目录目录摘要..............................................................IABSTRACT..........................................................II1绪论.............................................................11.1课题研究的背景和意义..................................................11.2研究现状..............................................................11.2.1传统控制方式.....................................................11.2.2现代控制方式.....................................................21.2.3存在的问题.......................................................21.3本文设计内容..........................................................32电厂化学水水质分析及处理..........................................42.1天然水中的杂质........................................................42.1.1悬浮物...........................................................42.1.2胶体.............................................................42.1.3溶解物质.........................................................42.2电厂化学水除杂........................................................52.3工艺流程选择..........................................................53系统硬件配置......................................................73.1PLC的介绍............................................................73.2PLC的特点............................................................73.3PLC的选择............................................................83.4PLC程序的I/O地址分配................................................83.5PLC外部接线图.......................................................103.6双料过滤器...........................................................133.6.1双料过滤器的概述................................................133.6.2双料过滤器的工作原理............................................133.6.3双料过滤器的优点................................................133.7反渗透装置...........................................................133.7.1反渗透装置的概述................................................133.7.2反渗透的工作原理................................................143.8混床................................................................153.8.1混床............................................................153.8.2除碳器..........................................................153.9除盐水箱.............................................................163.10其它检测仪器........................................................183.10.1电导率变送仪...................................................183.10.2压差变送器.....................................................183.10.3液位变送器.....................................................184系统的软件设计及调试.............................................194.1程序设计流程.........................................................19攀枝花学院本科毕业设计（论文）目录4.1.1双滤料过滤器运行流程............................................194.1.2反渗透运行流程..................................................214.1.3混床运行流程....................................................214.2程序设计.............................................................234.2.1STEP7软件介绍..................................................234.2.2梯形图介绍......................................................234.3程序调试.............................................................234.3.1长时间定时......................................................234.3.2双滤料过滤器运行................................................264.3.3混床反洗再生....................................................27结论..............................................................31参考文献.......................................................32附录A：系统控制程序梯形图.........................................33附录B：系统控制程序指令语句.......................................51致谢........................................................