徐强专业综合设计说明书

吉林化工学院信息与控制工程学院专业课程设计吉林化工学院信控学院专业综合设计说明书列管式换热器自控设计学生学号：07510135学生姓名：徐强专业班级：自动0701指导教师：吕春兰职称：副教授起止日期：2010.10.31～2010.11.21吉林化工学院列管式换热器自控系统设计JilinInstituteofChemicalTechnology吉林化工学院信息与控制工程学院专业课程设计-14-目录第1章专业综合设计的目的··························································································5第2章前言················································································································62.1列管式换热器自控方法分析·················································································62.2列管式换热器工作原理························································································7第3章列管式换热器工艺流程·······················································································83.1串级控制系统基本概念即组成结构········································································83.2串级控制系统的设计···························································································93.3串级控制系统的工业应用···················································································11第4章相关仪表选型··································································································124.1差压变送器·····································································································124.2电磁流量计·····································································································134.3隔膜式压力表··································································································144.4铠装热电偶·····································································································154.5温度变送器·····································································································164.6操作台的选择··································································································184.7显示器的选择··································································································19第5章S7-300PLC在系统中的应用···············································································205.1S7-300PLC简介······························································································205.2PLC工作原理·································································································225.2.1输入采样阶段·························································································225.2.2用户程序执行阶段···················································································225.2.3输出刷新阶段·························································································22第六章可编程控制器（PLC）的安装、维护和检修···························································236.1PLC的安装·····································································································236.2PLC系统的电源接线·························································································246.3接地··············································································································246.4输入接线········································································································246.5输出接线········································································································246.6PLC的维护和检修····························································································25致谢·························································································································26列管式换热器自控系统设计参考文献···············································································································27吉林化工学院信息与控制工程学院专业课程设计-14-第1章专业综合设计的目的本设计是学生第一次进行的综合性专业训练，是自动化专业的一个重要教学环节，其设计目的是进一步巩固和加深对所学理论知识的理解，培养学生独立分析和解决工程实际问题的能力，使学生对自控设计有较完整的概念，培养学生综合运用所学的控制理论、仪表、控制工程等知识进行工程设计的能力，进一步提高设计计算、制图、视图、编写技术文件，查阅参考文献与资料、仪表类型选择的能力。通过此次设计，培养学生树立为社会主义建设服务的观念。设计者应该有敢于创新和勇于负责的精神，从投入施工的角度来严肃对待自己的设计，使自己的设计能最大限度满足生产实际需要，既经济，又可靠。要善于利用书本知识，而又不迷信书本，要善于独立思考，反对粗心大意，草率从事以及不负责的态度；设计中应善于全面综合的考虑各项复杂因素，有选择性吸收前人的成果，发挥主观能动性，大胆提出创造性的设计方案。列管式换热器自控系统设计第2章前言列管式换热器主要由壳体、管束、折流板、管板和封头等部件组成。管束安装在壳体内，两端固定在管板上。封头用螺栓与壳体两端的法兰相连。它的主要优点是单位体积所具有的传热面积大、结构紧凑、传热效果好。结构坚固，而且可以选用的结构材料范围广，故适应性强、操作弹性较大。列管换热器的构造原理、特点：列管换热器（又名列管式冷凝器），按材质分为碳钢列管换热器，不锈钢列管换热器和碳钢与不锈钢混合列管换热器三种，按形式分为固定管板式、浮头式、U型管式换热器，按结构分为单管程、双管程和多管程，传热面积1～500m2，可根据用户需要定制。..列管换热器应用构造具有耐腐蚀性能好，耐温高、导热好、体轻、占地面积小，无毒性，不结垢，安装维修方便，应用面广、价格低廉等优点一九八零年化工十多个单位的专定、学者、技术人员领导同志参加。鉴定意见认为：在填充改性，二次成型加工，专用工具焊接等方面的研制工作都是成功的。在国内是先进的，在应用石墨填充改性聚丙烯并制成换热器方面也是首创的。实践证明，效果良好，建议推广应用。并用于同年荣获中华人民共和国化学工业部重大成果奖。列管换热器主要特点：1．耐腐蚀性：聚丙烯具有优良的耐化学品性，对于无机化合物，不论酸，碱、盐溶液，除强氧化性物料外，几乎直到100℃都对其无破坏作用，对几乎所有溶剂在室温下均不溶解，一般烷、径、醇、酚、醛、酮类等介质上均可使用。2．耐温性：聚丙烯塑料熔点为164-174℃，因此一般使用温度可达110-125℃。3．无毒性：不结垢，不污染介质，也可用于食品工业。4．重量轻：对设备安装维修极为方便。2.1列管式换热器自控方法分析列管式换热器具有传热面积大、结构紧凑、传热效果好等特点，在化工企业中广泛用于生产过程的加热、冷却及废热回收等场合。南通江山农化公司的草甘膦合成工段使用列管式换热器用来回收变换气的热量以提高进饱和塔的热水温度，从而为合成反应提供必要的条件。换热器循环水泵采用三相异步电机带动，原来未使用调速方式，换热器的进水量和出水量是固定的，由于回收到的变换气温度波动较大，导致换热器出水口的温度难以控制在规定的范围内，给合成工段的生产质量造成了一定的影响，主要反映在草甘膦的有效含量偏差过大。基于上述原因，在确保生产工艺要求的前提下，决定采用通用变频器对循环水泵电机进行调速控制。变频器则在可编程控制器的程序控制下工作，其控制信号由可编程控制器综合气体温度以及出水口温度经算法运算后给出。本文结合该变频调速系统的具体应用，重点分析其中控制系统的结构和工作原理。吉林化