CHAPTER 6: HEAT TRANSPORT CONTROL SYSTEMS …

1 instrumentation &ControlChulalongkomUnive rsityIntroductionChapter6:HeatTransportC on,,,J!SystemsModule3:HeatTransportBleed ControlCHAPTER6:HEATTRANSPORTCONTROLSYST EMSMODULE3 resultofeithertoohigha :(a) Ctoapproximately2 MPaand210 Cin thebleedcondenser, ,BleedCondenserPressureControl.(b)Tomain tainanadequateinventoryin thebleedcondenser, ,bleedcondenserlevelcontrol.(c)Tolowerth etemperatureofBleedfromthebleedcondenser toapproximately30 CbeforepassingthroughtheIIXcolumns, ,temperaturecontrolof bleedcooler.(d)Inordertoavoidbreakdownof IXresinsbya bleedtemperaturein excessofapproximately50-60 C,toprovidea meansofeffective temperaturecontrolof thebleedcoolerat theexpense,Ifnecessary,ofthecontrolfunct ionlistedin(b), , 3 1 instrumentation &ControlChula/ongkomUnive rsityChapter6:HeatTransportConcrolSystem sModule3:HeatTransportBleedControleV113r -------r--~!

2 ,..,.. ~uD9..PWirpa~---; ISPRAY'REFWCCOLS-+.. '--:" ~- ,, Thesetpointsofthetwopressurecontrolloops arestaggeredwiththerefluxsetpointthelowe st( ). Aslongasthepressureissuccessfullycontrol ledbytherefluxmethod,thesprayvalvewillno tbeopened. Shouldthebleedcondenserpressureriseunche ckedbytherefluxsystem,thespraycontroller willbegintodrivethesprayvalveopen. Thepreferredmethodofbleedcondenserpressu recontrolisbythrottlingtherefluxvalve(CV 111). Thebackupmethodofpressurecontrol,sprayva lve(CV113)regulation,isnotdesirablebecau seitresultsinextraflowthroughtheIXcolumn sandpromotesdegassingofthe020in thecondenser. 2 instrumentation &ControlChulalongkomUnive rsityChapter6:HeatTransportCOntrolSystem sModule3 (> "._lat1nqCV553tooling'HateX'r--~-~~'f'-- :c< ,EEDT22 Duringnormalsystemoperation,thebleedcond enserlevelisregulatedbythrottlinganoutfl owcontrolvalve(CV122orCV123).)

3 Thiscontrolproblemcanbeconsidered,ingene ral,asthelevelcontrolofa tankbyoutflowregulationwherethetankis suppliedwitha nonconstantinflow. Aduplicatedsystemisemployedwithstaggered setpointsfortheidenticallevelloops. Considerthelevelloopidentifiedwithtagnum ber122(LT-122toCV122) (CV122) , 122is fedtoa lowselectrelay(LM-122)whichwillpassthe12 ]lowestofthetwosignalsapplied,( ,10rnAand12rnAinput,10rnAoutput). :BleedCondenserLevelandBleedauto/manuals tation(HC-122)sothatmanualcontrolTmeatre Controloftheoutflowvalveispossibleifthec ontrollere p r (AX122)whichallowstheelectroniclooptobei nterfacedwiththepneumaticactuatorofCV122 . Theoperationofthelevellooptagged123isIde nticalto122exceptthatthesetpointofLC-123 isapproximatelytwentypercenthigherthanth esetpointofLC-122.

4 ( :60%,LIC-123setpoint:82%).Aslongasthelev elis regulatedbyloop122, sensedbyanRTDwhichproducesachangeinresis tanceproportionaltothemeasuredchangein appliedastheinputtotwotemperaturecontrol lers(TIC-553,TIC-122) :HeatTransportConcrolSystemsModule3: heat TransportBleedControl4-20 +-+Figure3 directactingsothatanincreaseineffluentte mperaturewillcausetheairtoopencontrolval ve(CV-553) (TIC-554)is30 C,approximately6 , :HeatTransportCom,,}/SystemsModule3: heat TransportBleedControl1'0:LX~~-"' '--,--'cV-122 TemperatureOverrideofLevel!fuLevel~ ;~-~ ~---I ; Fornormaloperation, - - - (CV-122)ispositionedasa functionofthecontrolFigure4 ,andthiscontrolsignalis appliedasoneof theinputstothelowselectrelay(LM-122). ,thelevelcontrolsignalwillincreaseasthel evelrises,andCV , ,andthetemperaturecontrollerwillberegula tingthecontrolvalve(CV-122) , (requestedbyTIC-553) lowlimitis setonthetemperaturecontrollersignal(TIC- 122)tolimittheclosingofthelevelvalve(CV- 122)to10% 3 5 instrumentation &ControlChulalongkomUnive rsityChapter6:HeatTransportConllolSystem sModule3:HeatTransportBleedControlRespon setoa ReactorTripFora feedandbleedtypesystema reactortripwouldcause,due,tothegrossener gymismatchthatexistsundersuchconditions, anincreaseinfeedvalveopeningandbleedvalv esgoingtoa minimumopeningpositioninanattempttopreve ntinventoryshrinkage(turbineremovingheat fromsystem).

5 Duetothelimitedresponserateofthissystemt hefeedactionmustbeaugmentedbytheremovalo ftheultimateheatsink, ,a reductionin servicewaterflowin fastspeedergearrunbacktore-establishthee nergybalanceat a 3 6 instrumentation &ControlChulalongkomUnive rsityChapter6:HeatTransportCon"01 SystemsModule3 ,plusanysprayflow, ,inturn, ,perhaps,benecessarytoinvokethetemperatu reoverrideofbleedcondenserlevelfora shortperiodof turbinetripwillinitiatea ,foranyreasonatall,thisstepbackdoesnotha ppen,a 7 instrumentation &ControlChulalongkomunive rsityChapter6:HeatTransportCOt,..vISyste msModule3:HeatTransportBleedControlIX41 MVI,ftI!$SUllim.\IFF1 TllDIPHTSF igure5:OverallControlSchemeforHTS.,,Simp lifiedOverallHTSC ontrolSchemeTheprinciplecomponentsandthe irrolein theoverallcontrolschemeareasfollows:CV1 Refluxflowcontrolvalve ;opensinnormal(atpower) up,wheninventoryswellis largest,condenserMV3is bypassedwithflowdirecttoD20