What are factors affecting condenser performance
- 1. What are factors affectingcondenserperformance? Condenseristhe mainheatsinkinthe entire powercycle.Plantheatrate ismostly dependingon condenserperformance. There are twotypesof condenserare availableinpowerplant, one iswater cooledandanotherisair cooledcondenser.Aircooled condenseris consideredwhenthereiswater availabilityisless. Isentropicheatdropsthoughthe turbine dependsonthe inletsteampressure & temperature andcondenservacuum.If the vacuumincondenserislower,the workdone bythe turbine will be reduced. In case of watercooledcondensercoolingwatersuppliedto the surface condensertube sidetocool the exhauststeamfromthe turbine. Inthisprocess undissolved airorgassesare separated andisevacuated fromthe shell side byejectorof vacuumpumpto maintainthe vacuum. Normallyitistwopass , shell and tube type heatexchanger. We needtofamiliarize withthe followingterms: TTD- Terminal temperature difference =T3- T2 T3 – ExhaustSteam(Saturation) temperature,T2- CW outletTemperature TR- Temperature Difference =T2- T1 T1- CW inlettemperature CondenserEfficiency= (CW temperature rise)/(MaximumTemp Difference) = TR/ (T3- T1)x100% dTm=LMTD= Log mean temperature difference = (T2-T1)/((ln(T3-T1)/(T3-T2))
- 2. CW Mass Flow Rate , m= dUA,where d – densityof water U- velocityof water A-condensersurface area Q= Heat transfer rate in condenser=K.A.dTm =m.Cp .(T2-T1) consideringno otherheat loss taking place insteady state condition K- heat transfercoefficientof tube A-Surface area m- massflowrate (CW) Cp- specificheatof water So. CondenserEffectivenessisdependson CWtemperature difference orratioof temperature difference,specificheatof water,massflow rate of coolingwater,heattransfercoefficientof condenser tube and surface areaof condensertubes. CleanlinessFactor:CF= Kt/Ki ,,Ki isinitial heattransfercoefficient ,thiscanbe derivedfromthe above formula. Kt isheat transfercoefficient afterTime t.
- 3. CF is100% whenit isnewand cleanedcondition.Afterrunningsometimethisvalue will be reduced. Normallysystemisdesignedfor85%CF. FoulingFactor: FF= 1/Kt-1/Ki , thisfactor isusedto predictthe performance trendof the condenser Theoretically1mmHgreductioninvacuumgenerationlossof 4MW and there is2.5% of efficiencyloss. Condenserperformance candegrade due tofollowingreason: Airbindingonthe shell side: Thisisdue topoor performance of the steamejector/vacuum pumpor air ingressintothe system. Biofouling:This can be avoidedbyproperchlorinationof the CWsystem Scaling:ProperCW quality- pH,TDS,hardness,COC,conductivityetcare tobe maintainedto avoidthe scalinginside the tube surface. Silting:Obstructioninthe tubescan occurs due to siltdepositionandchokingof the tubesby filmof coolingtowerordebriscarriedawayby coolingwater. Dailymonitoringof TTD,TR, CF and FF easilywillshow the gradual deteriorationof the parameters. Remedies: Online condensertube cleaningsystemwill helptomaintainthe above parameters Chemical treatmentof CoolingWaterandmonitoringof coolingwaterparametersare required Inspectionandcleaningof waterbox,tubesare tobe done duringperiodical shutdown
- 4. If the hard scale isformedinside the tube,,chemical cleaningisbe done Pluggedtubesare tobe replacedduringshutdownof the unit.Itshouldnotexceed5% of the total tubes.