ThecondensatepipesizingchartThecondensatepipesizingchart(Figure14.3.5)canbeusedtosizeanytypeofcondensateline,including:Drainlinescontainingnoflashsteam.Linesconsistingoftwo-phaseflow,suchastrapdischargelines,whichareselectedaccordingtothepressureseithersideofthetrap.Thechart(Figure14.3.5):Worksaroundacceptableflashsteamvelocitiesof15-20m/s,accordingtothepipesizeandtheproportionofflashsteamformed.Canbeusedwithcondensatetemperatureslowerthanthesteamsaturationtemperature,aswillbethecasewhenusingthermostaticsteamtraps.Isusedtosizetrapdischargelinesonfull-loadconditions.Itisnotnecessarytoconsideranyoversizingfactorsforstart-uploadortheremovalofnon-condensablegases.Mayalsobeusedtoestimatesizesforpumpedlinescontainingcondensatebelow100°C.ThiswillbediscussedinTutorial14.4.Fig.14.3.5CondensatepipesizingchartUsingthecondensatepipesizingchart(AlsoavailableinAppendix14.3.2)Establishthepointwherethesteamandcondensatepressuresmeet(lowerpartofthechart,Figure14.3.5).Fromthispoint,moveverticallyuptotheuppercharttomeettherequiredcondensaterate.Ifthedischargelineisfalling(non-flooded)andtheselectionisonorbetweenlines,choosethelowerlinesize.Ifthedischargelineisrising,andthereforelikelytobeflooded,choosetheupperlinesize.Note:Thereasoningemployedforthesizingofasteamtrapisdifferenttothatusedforadischargeline,anditisperfectlynormalforatrapdischargelinetobesizeddifferenttothetrapitisserving.However,whenthetrapiscorrectlysized,theusualancillaryequipmentassociatedwithasteamtrapstation,suchasisolationvalves,strainer,traptestingchamber,andcheckvalve,canbethesamesizeasthetrappingdeviceselected,whateverthedischargelinesize.Asteamtrappassingafull-loadof1000kg/hat6bargsaturatedsteampressurethroughafallingdischargelinedowntoaflashvesselat1.7barg.Asthedischargelineisnon-flooded,thelowerfigureof25mmisselectedfromthechart(Figure14.3.5).Fig.14.3.6Anon-floodedpressurisedtrapdischargeline(refertoExample14.3.3)Asteamtrappassingafull-loadof1000kg/hat18bargsaturatedsteampressurethroughadischargelinerising5muptoapressurisedcondensatereturnlineat3.5barg.Addthe0.5barstaticpressure(5mhead)tothe3.5barcondensatepressuretogive4bargbackpressure.Asthedischargelineisrisingandthusflooded,theupperfigureof32mmisselectedfromthechart,(Figure14.3.5).Fig.14.3.7Afloodedtrapdischargeline(refertoExample14.3.4)Asteamtrappassingafull-loadof200kg/hat2bargsaturatedsteampressurethroughaslopingdischargelinefallingdowntoaventedcondensatereceiveratatmosphericpressure(0barg).Asthelineisnon-flooded,thelowerfigureof20mmisselectedfromthechart,(Figure14.3.5).Fig.14.3.8Anon-floodedventedtrapdischargeline(refertoExample14.3.5)Apump-trappassingafull-loadof200kg/hat4bargsaturatedsteamspacepressurethroughadischargelinerising5muptoanon-floodedcondensatereturnlineatatmosphericpressure.The5mstaticpressurecontributesthetotalbackpressureof0.5barg.Asthetrapdischargelineisrising,theupperfigureof25mmisselectedfromthechart,(Figure14.3.5).Fig.14.3.9Afloodedtrapdischargeline(refertoExample14.3.6)Consideracondensateloadof200kg/htoareceiverandpump.Thepumpdischargerateforthismechanicaltypepumpistakenassixtimesthefillingrate,hence,thecondensateratetakenforthisexampleis6x200=1200kg/h.Becausethecondensatewillhavelostitsflashsteamcontenttoatmosphereviathereceivervent,thepumpwillonlybepumpingliquidcondensate.Inthisinstance,itisonlynecessarytousethetoppartofthechartinFigure14.3.5.Asthelinefromthepumpisrising,theupperfigureof25mmischosen.Note:Ifthepumpedlinewerelongerthan100m,thenextlargersizemustbetaken,whichforthisexamplewouldbe32mm.Ausefultipforlinesof100morlessistochooseadischargepipewhichisthesamesizeasthepump.ForfurtherdetailsrefertoTutorial14.4'Pumpingcondensatefromventedreceivers'.
