【正文】 I 基于 S7200PLC 紙漿濃度控制系統(tǒng)設計 摘 要 在造紙生產(chǎn)過程中，紙漿濃度是最重要的物理量之一，穩(wěn)定地調(diào)節(jié)紙漿濃度是實現(xiàn)工藝目標，達到質(zhì)量標準的重要環(huán)節(jié)，更有利于企業(yè)在節(jié)省生產(chǎn)成本的基礎上提高經(jīng)濟效益。為此本人設計了一基于 S7200PLC 的紙漿濃度控制系統(tǒng)，該系統(tǒng)自動檢測紙漿濃度，并與設定值進行比較產(chǎn)生偏差，經(jīng)過一定的控制算法輸出控制進水電動閥門開度，從而調(diào)節(jié)進入漿泵的稀釋水量，使輸漿管內(nèi)的漿料濃度發(fā)生變化，最終得到濃度穩(wěn)定的漿料。 本設計方案是使用內(nèi) 旋式紙漿濃度變送器測量實際紙漿濃度，將濃度信號轉(zhuǎn)換成420mA 標準信號，然后通過 A/D 轉(zhuǎn)換后反饋到控制器，與給定值進行比較，得到偏差。對得到的偏差按 PID 算法進行計算，以此調(diào)節(jié)白水入口電動閥的開度，從而實現(xiàn)對紙漿濃度的調(diào)節(jié)。并利用組態(tài)軟件 MCGS 設計人機界面，實現(xiàn)控制系統(tǒng)的實時監(jiān)控。在本設計中使用的是 Simens S7200 CN， CPU 型號為 224XP CN，由于 224XP CN 自帶兩個模擬量輸入和一個模擬量輸出接口，故無需額外使用模擬量擴展模塊。 目前， PLC 在國內(nèi)外已廣泛應用于鋼鐵，石油，化工，電 力，建材，機械制造，汽車，輕紡，交通運輸，環(huán)保及文化娛樂等各個行業(yè)。 使用情況大致可歸納為如下幾類 ：開關量的邏輯控制 模擬量控制 運動控制 過程控制 數(shù)據(jù)處理 通信及聯(lián)網(wǎng) 。其主要優(yōu)點有： ，抗干擾能力強 ，功能完善，適用性強 ，深受工程技術人員歡迎 、建造工作量小，維護方便，容易改造 ，重量輕，能耗低 。 關鍵詞： PLC 紙漿濃度 PID 算法 II The Design of Pulp Consistency Control System Based On The S7200 PLC Abstract In the process of paper production,the pulp consistency is one of the most important physical qualities, To ajust the pulp consistency stably plays an important role in achieving the process goals and meeting the quality it can help the Enterprise to improve the economy efficiency by saving production I designed a pulp consistency control system based on S7200 PLC， the system automatically detects the pulp consistency，biase and pare with set point, and after a certain control algorithm， the output signal can control the opening of the electric valve over the water inlet,which regulates water diluted into slurry pump, and the pulp consistency in the slurry pipe changes, finally we get a stable pulp consistency. This design uses the screw type pulp consistency transducer to measure actual pulpconsistency,the consistency signal is converted into standard 420 ma signal,and then A\D conversion convert the analog signal into digital signal and feedback to the controller， and after paring with the giver value,we get the the deviation by PID algorithm， then use the result to adjust the opening of the electric valve of the water inlet,so as to realize the adjustment of the pulp consistency. use the configuration software MCGS to design manmachine interface ,so as to realize the realtime monitoring of the control this design we chose the Simens S7200,224 XP CN as the controller,and because the 224 XP CN has two analog input and one analog output interface,it can meet the requiment,so we don’t have to use analog extended module. At present,at home and abroad the PLC has been widely used in steel,petroleum,chemical industry,electric power,building materials,machinery manufacturing,automobile,light textile,transportation,environment protection and cultural entertainment,and other usege can be roughly summarized as the following categories:1,the switch quantity logic control 2,analog control 3,motion control 4,process control processing 6,’s main advantages are : high reliability,strong antijamming ,lete,fully functional,high applicability,easy to learn and easy to use,weled by engineering and technical ,small amount of work of system design and construction,maintenance is convenient,easy to transform. 5,small size,light weight,low energy consuption. KEY WORDS: PLC PULP CONSISTENCY PID ALGORITHM III 目 錄 引 言 .........................................................................................................................................1 第 1 章 緒論 ...........................................................................................................................2 論文研究背景 .....................................................................................................................2 研究背景 .................................................................................................................2 紙漿濃度變送器的發(fā)展趨勢 .................................................................................2 PLC 的發(fā)展趨勢 ......................................................................................................2 控制算法的發(fā)展趨勢 .............................................................................................2 本文研究主要內(nèi)容 ............................................................................................................3 研究意義 ............................................................................................................................3 設計思路 ............................................................................................................................3 研究工作與成果 ................................................................................................................3 第 2 章 總體技術方案 ...........................................................................................................4 紙漿濃度工藝描述及系 統(tǒng)結(jié)構圖 ....................................................................................4 系統(tǒng)各組成模塊及控制方框圖 ........................................................................................4 方案的確定 ........................................................................................................................5 第 3 章 系統(tǒng)硬件設計 ...........................................................................................................6 濃度變送器的原理 ............................................................................................................6 力學法濃度測量原理 ...............................................................................................6 內(nèi)旋式濃度變送器的原理 .......................................................................................6 內(nèi)旋式變送器的數(shù)學模型 .......................................................................................7 執(zhí)行器的原理 .......................................................................................................