一個簡單的仿真建模濕式石灰石煙氣脫硫技術裝置畢業(yè)論文外文翻譯

1、外文翻譯AsimplerealisticmodelingoffullscalewetlimestoneFGDunitsABSTRACTAmodelofwetlimestonefluegasdesulfurization(WLFGD)systemhasbeendevelopedbasedontheuseofthenumberoftransferunits(NTU)heightoftransferunit(HTU)focusedtofull

2、scalecoalfiredpowerplants.ThemodeldescribestheprocessoccurringintheabsberasthemostimptantstepintheWLFGDsystembyestablishingwhatincreaseinSO2removalcanbeachievedasthehigherlevelsofnozzlescomeprogressivelyintoservicewhenin

3、itiallythefirstsprayheaderisoperatingalonekeepingtheotheroperatingconditionsundercontrol.ThisrelativeimprovementoftheSO2removalcanbeobtainedfromonlyonedatum:thenumberofmasstransferunitswhenonlythefirstspraylevelisonservi

4、ce.Themodelcomputesthegainsinboththevolumetricoverallmasstransfercoefficientthenumberoftransferunits.Themodelcanbeusedtoevaluatedatachangesinanexistingfullscalesystemaswellastoevaluateproposedsystemdesignsevenasapredesig

5、ntoolinrelationtothenumberofspraylevelsonserviceundercontrolledoperatingconditions.Themodelistestedonthebasisofsomedatatakenfromapowerplantfromtheliterature.Themodelresultsagreewellwiththerealpublisheddata.1.Introduction

6、NowadaysdifferentdesulfurizationtechnologiesareavailabletocontrolSO2emissionincoalfiredpowerstations.Themostwidespreadiswetlimestonefluegasdesulfurization(WLFGD)whichhasundergoneconsiderabledevelopmentoverthepast30yearsi

7、ntermsofSO2removalefficiencyreliabilitycosts.LimestoneisgenerallyquiteabitcheaperthanlimemakingitmepopularflargeFGDsystems.TherefewetscrubbersespeciallywetlimestonedesulfurizationscrubbersarethefrontrunningFGDtechnologie

8、sInthisprocessthefluegasistreatedwithlimestone(calciumcarbonate)slurrynmallyinaspraycolumn.Limestoneismixedwithwaterinaslurrysupplytank.Thefreshlimestoneslurryisfedtotheabsbersump.ThelimestonegypsumslurryispumpedfromApar

9、tfromthemathematicalmodelsfeaturedtochemicalaspectsnowCFDcodeallowstodealwiththegasslurryflowpatternswhichnmallyhavebeenassumedtobesimplifiedones.Despiteintensivemodelingwkindustrialequipmentismostlydesignedbyscaleupofpr

10、ocessdataobtainedinpilotplantsthusillustratingthedifficultyintheapplicationofthesemodelstothefullscaleplants.Thecomplexchemistrythesimultaneousmassheattransferinvolvedinthewetlimestonedesulfurizationprocessisnotaneasytas

11、ksosolvingthesetofequationsisverytimeconsumingnotonlyfadynamicmodelbutalsoevenfthesteadystatecase.Therefeasimplemodelbasedoneasyglobalconceptwouldbeusefultochemicalengineersfwhotocontinuouslysolvetherigousmodelmaybeimpra

12、cticalthusitmaybewelcometoconsiderarealisticapproachwhendealingwithamodelofaWLFGDunitinfullscaleplant.Thispaperdoesnottrytodevelopadetailedmodelbutasimpledirectlyapplicablemodeltofullscaleplantsthustheaimofthepresentwkis

13、todescribearealisticmodelthatcanbeusedasatoolftheanalysisoftheWLFGDsprayunitsinfullscalecoalfiredpowerplants2.GeneraloutlineofthemodelThemostimptantprocessintheWLFGDsystemistheabsptionofsulfurdioxide.Sulfurdioxideisabsbe

14、dinthesprayabsptionzonebyreactingwiththelimestoneslurryssothechemicalabsptionintheabsberisthemostcomplicatedsignificantstepinscrubber.Inthismodelingwklimestonedissolutioncrystallizationofgypsumareundercontrolbyclosingcon

15、trolloopsthatmanipulatefreshlimestoneslurrymakeupwaterflowrateagitationsludgeflowratecontrollingthustheholdingtanklevelpH.FurthermesulfiteoxidationwhichisoffundamentalimptanceinWLFGDprocesswillbeundercontrolledconditions

16、bymanipulatingtheairflowrateenteredtotheholdingtankthesulfiteoxidationratehasbeenassumedtobeafixedrateindependentofthesulfiteconcentration.Therefetheabsbentdissolutionoxidationcrystallizationthatoccurintheslurryzonewilln