盐水冷冻

吉林学院专业综合设计说明书盐水冷冻站自控设计说明书学生学号：学生姓名：专业班级：指导教师：起止日期：JilinInstituteofChemicalTechnology吉林学院专业综合设计说明书-I-专业综合设计任务书一、设计题目：盐水冷冻站自动控制系统设计二、设计目的1、进一步巩固和加深所学的自动化专业的理论知识，培养学生设计、计算、绘图、计算机应用、文献查阅和报告撰写等基本技能；2、熟练掌握工业过程控制系统的常规设计过程，培养学生实践动手能力及独立分析和解决工程实际问题的能力；3、熟练运用AutoCAD等绘图工具制图；4、培养学生的团队协作精神、创新意识、严肃认真的治学态度和严谨务实的工作作风。三、设计任务及要求1、熟悉工艺流程；根据工艺要求，确定自控方案；用AutoCAD绘制工艺管道及控制流程图；2、仪表选型及调节阀和节流装置的计算；3、绘制施工图，编制自控设备表相应表格。四、设计时间及进度安排设计时间共三周（2006.12.11～2006.12.29）,具体安排如下表：周安排设计内容设计时间第一周熟悉工艺流程，查找相关资料，根据工艺要求，确定自控方案；绘制工艺控制流程图。2006.12.11～2006.12.15第二周进行仪表选型及调节阀计算；绘制单回路图。2006.12.18～2006.12.22第三周绘制仪表接线端子图；供电系统图，填写自控设备相应表格。完成并提交课程设计说明书及相关电子文档。课程设计答辩。2006.12.25～2006.12.29五、指导教师评语及学生成绩指导教师评语:年月日成绩指导教师(签字):盐水冷冻站的自控设计-II-目录专业综合设计任务书······································································································I第1章绪论·················································································································11.1工艺流程介绍·······································································································11.2相关数据及设计条件······························································································11.3设计资料明细·······································································································1第2章控制方案设计····································································································32.1蒸发器控制方案分析与设计·····················································································32.2分离器控制方案分析与设计·····················································································32.3冷凝器控制方案分析与设计·····················································································4第3章调节阀计算·······································································································5第4章器件选型及说明·································································································84.1仪表选型及说明····································································································84.1.1调节阀···········································································································84.1.2远传压力仪表·································································································94.1.3温度计·········································································································104.1.4流量仪表·····································································································114.1.5液位计·········································································································134.1.6配电器········································································································134.2控制器与I/O模块选型及说明················································································14第5章施工图说明·····································································································16第6章结束语············································································································18参考文献···················································································································19附录·························································································································20吉林学院专业综合设计说明书-1-第1章绪论1.1工艺流程介绍盐水冷冻站由盐水泵，立式蒸发器，氨气压缩机，液氨分离器，氨气冷凝器，氨储存器等主要设备组成，其工艺流程图如附图所示。氨气经过氨压缩机加压以后，进入氨冷凝器，用工业用水冷凝变成液体氨，在冷凝器底部输送到氨储槽，液氨靠自身压力送到立式蒸发器里边的蛇型管，蛇型管中的液氨蒸发时吸收大量的热量，而使盐水的温度冷冻为-13℃～-17℃，则液氨变为气氨，气氨中混有液氨，通过液氨分离器，其中液氨又回到蛇型管里继续蒸发，而气体氨进入氨压缩机之后，进行循环使用，氨气漏损以后补充液氨，以保证盐水正常冷冻。1.2相关数据及设计条件有关数据和已知条件：(1)氨蒸发器调节通道的动特性可以近似的看成一阶惯性环节和纯滞后环节相串联的对象。其放大倍数Kp=0.6,T=0.8分,t=5秒.(2)盐水流量Q=240m3/h,密度p=1.21～1.24g/cm2,Qmax=288m3/h,压力P=4.5kgf/cm2,温度T=-13℃～-17℃(3)液氨流量Q=200m3/h,密度p=0.98g/cm3,压力P=6kgf/cm2.(4)冷凝器冷却水的流量Qmax=150m3/h,压力P=6kgf/cm2,温度T=10℃.(5)就地指示盐水泵出口压力从氨储槽液面。(6)要求在仪表盘上记录盐水泵出口压力变化，温度变化，盐水流量，压缩机输入，出口压力变化。(7)要求控制蒸发器蛇型管中液氨的液面。(8)设计尺寸：液氨分离器Φ=1m,H=2m冷凝器Φ=1.3m,H=6m立式蒸发器2m×5m×1.5m(9)硬件条件：计算机。(10)软件条件：AutoCAD2005简体中文版，Office2003（MicrosoftWord2003，MicrosoftOfficeAccess），吴忠仪表厂调节阀计算软件包。1.3设计资料明细(1)带控制点的工艺流程图如附录图(1－1)所示。(2)控制回路图如附录图(1－2)至图(1－4)所示。(3)端子接线图如附录图(1－5)至图(1-7)所示。(4)系统供电原理图如附录图(1－8)所示。(5)综合设计表图纸目录如附录表(1－1)所示。盐水冷冻站的自控设计-2-(6)远传压力仪表规格数据表如附录表(1－2)所示。(7)配电器规格数据表如附录表(1－3)所示。(8)电源箱规格数据表如附录表(1－4)所示。(9)温度计规格数据表如附录表(1－5)所示。(10)系统I/O数据表如附录表(1－6)所示。(11)流量仪表规格数据表如附录表(1－7)所示。(12)调节阀计算数据表如附录表(1－8)所示。本设计是基于工程设计院实际工程项目。所以设计的原则是不仅考虑知识点的综合应用和各控制点控制方案的确定，并尽量考虑实际工程的应用效果。吉林学院专业综合设计说明书-3-第2章控制方案设计氨气经过氨压缩机加压以后，进入氨冷凝器，用工业用水冷凝变成液体氨，在这个过程中，主要的影响因素有氨气的进入量和冷却水的补给量以及冷凝器中冷却水的液位。液体氨在冷凝器底部输送到氨储槽，液氨靠自身压力送到立式蒸发器里边的蛇型管，蛇型管中的液氨蒸发时吸收大量的热量，而使盐水冷冻，此过程中主要影响因素有蒸发器中液氨的液位高低，压力大小，冷却回盐水的量和冷冻盐水的出水流速问题。则液氨变为气氨，气氨中混有液氨，通过液氨分离器，其中液氨又回到蛇型管里继续蒸发，而气体氨进入氨压缩机之后，进行循环使用，在液氨分离器中主要控制量有氨气压力和液氨的液位这两个，下面将具体分析每个回路的控制方案。2.1蒸发器控制方案分析与设计立式蒸发器作为主要的反应器，其作用直接影响到这个设计的成功与失败。因此必须严格把蒸发器出口温度做为主控制对象。在整个回路中，又存在冷冻回盐水这样一个干扰量，对系统会产生影响，所以，用单回路是不行的，因此我们采用串级控制方案。主控对象已经确定为蒸发器的出口温度，接下来就要确定副被控变量，们可以从压力，液位这两个参数中选择。那么我们先来分析下以蛇型管中液氨的压力作为副被控变量这种方案。温度的输出是作为压力给定的，由于是对压力的控制，在实际控制中，与力是没有关系的，对温度的调节起不到作用，所以这种方案不可行。立式蒸发器取盐水的温度作为液位的