资源描述:
《电气工程与自动化专业外文翻译--(中英文对照)温度控制简介和pid控制器--》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、河北建筑工程学院毕业设计(论文)外文资料翻译系别:电气工程系专业:电气工程及其自动化班级:姓名:学号:外文出处:SpecializedEnglishForArchitecturalElectricEngineeringandAutomation附件:1、外文原文;2、外文资料翻译译文。指导教师评语:签字:年月日注:请将该封面与附件装订成册。1、外文原文IntroductionstotemperaturecontrolandPIDcontrollersProcesscontrolsystem.Automaticprocesscontrolisco
2、ncernedwithmaintainingprocessvariablestemperaturespressuresflowscompositions,andthelikeatsomedesiredoperationvalue.Processesaredynamicinnature.Changesarealwaysoccurring,andifactionsarenottaken,theimportantprocessvariables-thoserelatedtosafety,productquality,andproductionrate
3、s-willnotachievedesignconditions.Inordertofixideas,letusconsideraheatexchangerinwhichaprocessstreamisheatedbycondensingsteam.TheprocessissketchedinFig.1Fig.1HeatexchangerThepurposeofthisunitistoheattheprocessfluidfromsomeinlettemperature,Ti(t),uptoacertaindesiredoutlettemper
4、ature,T(t).Asmentioned,theheatingmediumiscondensingsteam.Theenergygainedbytheprocessfluidisequaltotheheatreleasedbythesteam,providedtherearenoheatlossestosurroundings,iiithatis,theheatexchangerandpipingarewellinsulated.Inthisprocesstherearemanyvariablesthatcanchange,causingt
5、heoutlettemperaturetodeviatefromitsdesiredvalue.[21Ifthishappens,someactionmustbetakentocorrectforthisdeviation.Thatis,theobjectiveistocontroltheoutletprocesstemperaturetomaintainitsdesiredvalue.OnewaytoaccomplishthisobjectiveisbyfirstmeasuringthetemperatureT(t),thencomparin
6、gittoitsdesiredvalue,and,basedonthiscomparison,decidingwhattodotocorrectforanydeviation.Theflowofsteamcanbeusedtocorrectforthedeviation.Thisis,ifthetemperatureisaboveitsdesiredvalue,thenthesteamvalvecanbethrottledbacktocutthestearrflow(energy)totheheatexchanger.Ifthetemperat
7、ureisbelowitsdesiredvalue,thenthesteamvalvecouldbeopenedsomemoretoincreasethesteamflow(energy)totheexchanger.Allofthesecanbedonemanuallybytheoperator,andsincetheprocedureisfairlystraightforward,itshouldpresentnoproblem.However,sinceinmostprocessplantstherearehundredsofvariab
8、lesthatmustbemaintainedatsomedesiredvalue,thiscorrectionprocedurewouldrequi