毕业论文基于PLC的自动加药系统设计

摘 要

该系统研究的对象是一种简单且具有一定自动化程度的“自动加药系统”，它不仅能用在锅炉上还能用在其它类型的需加药处理的生产设备及系统中。控制方案中PLC采用德国西门子S7-200系列可编程控制器，CPU主机选用CPU226，模拟输入模块选用EM235.

触摸屏采用SIEMENS TP170系列彩色触摸屏TP170B COLOR，可以方便的实现对控制系统的操作、监控和参数设置等功能。由PH在线分析仪、PLC、变频器组成的闭环控制自动加药系统，增强了控制先进性和可靠性。此套自动加药系统的投入彻底改变了以前人工加药不准带来的经济损失且对于节省人力、降低消耗、确保炉水安全、保证水质的稳定性，产生良好的经济效益和社会效益。这样就可以实时的检测到加药系统的相关参数，对药液做一些实时的控制。

人机界面和PLC的有机结合，借助其产品的功能，能够很灵活的构造控制方案，它相对传统的电气控制方案具有更高的可靠性，控制更精确。采用触摸屏与PLC控制，整个加药系统设自动、手动两种可选择的方式，能稳定的给锅炉加药，使炉内水时刻保持一定得药液浓度，保证炉内的各项水指标基本平稳。能克服老式加药装置加药配药不方便弱点，有效的提高了锅炉的自动化程度。加药系统操作简单、安全、可靠，设有电机搅拌器、溶解药剂所需时间可根据实际情况设定可控制药液的温度，可完成自动加药及自动清洗等。

关键词：PLC；触摸屏；加药系统

Abstract

This paper studies and discusses an "Automatic Dosing System" which is simple and to

some extent automatic. The system can be used not only in the boiler but also in other types

of manufacture equipment and system where dosing is needed.with its product features ,the

structure can be very flexible control program, It is relatively conventional electrical control

scheme is more reliable ,more accurate control .In control program the PLC adopts Siemens

S7-200 series programmable logic controller, CPU host CPU226, optional analog input

module EM235, touch-screen SIEMENS TP170 series color touch screen series TP170B

COLOR. TP170B COLOR touch screen ,which is a very high performance and cost-effective.

So it is easily to realize the operation, monitoring and parameter setting of the control system .

By the online analyzer, PLC, inverter consisting of closed-loop control automatic dosing

system to enhance the control of nature and reliability. This set of automatic dosing system

into completely changed the previous manual dosing allowed for the economic losses and

save manpower, reduce consumption and ensure safety of boiler water to ensure the stability

of water to produce good economic and social benefits. This can be detected in real-time

dosing system parameters, on the liquid to do some real-time control.

The combination of Man-machine interface and PLC with the functions of their products

can make the construction of control program become flexible, and compare to traditional

electrical control program, the system is more reliable and control more accurately .The use of

touch screen and PLC control and the two alternative ways for dosing (manual-automatic) of

the whole system increases the stability of dosing to the boiler so as to maintain a certain

concentration of the pharmacy and guarantee the stability of the water indicators in the boiler,

and overcomes the inconvenience during the dosing and prescribing, so effectively improves

the automation of the boiler .The dosing system with electric mixer is simple, safe and

reliable. The time required for dissolution of pharmaceutical can be set according to the actual

situation. The temperature of pharmaceutical can be controlled. The dosing and cleaning can

be automatically completed

Keywords: PLC; touch screen; dosing system

目 录

第1章 绪论 ............................................................... 1

1.1课题背景 ........................................................................ 1

1.2 锅炉控制研究的背景和意义 .................................................... 2

1.3课题研究的主要内容 ............................................................ 3

1.4 锅炉加药处理的特点及应注意的问题 .......................................... 3

第2章 硬件设计 ........................................................... 5

2.1控制方案选择 ................................................................... 5

2.1.1 S7-200工作原理 ................................................. 5

2.1.2方案概述 ......................................................... 7

2.1.3加药系统的组成 ................................................... 7

2.1.4加药系统的目标和原理 ............................................. 8

2.1.5 PH值控制方法的研究 .............................................. 9

2.1.6加药系统的特点 ................................................... 9

2.1.7加药系统的控制功能描述 .......................................... 10

2.2硬件设计 ....................................................................... 10

2.2.1主电路设计 ...................................................... 10

2.2.2 PLC控制 ........................................................ 11

2.2.3 EM235模拟量模块接线 ............................................ 12

2.2.4自动加药装置技术参数 ............................................ 13

2.2.5系统的PID控制 .................................................. 13

2.2.6 PID控制器的参数整定 ............................................ 15

2.3 自动加药系统的硬件选型 ........................................................................................... 16

2.3.1 PLC的选型 ...................................................... 16

2.3.2 触摸屏选型 ..................................................... 18