Onlineefficiencyanddiagnostics
ofacoalfiredBoiler
Name: Kota. Bhanu Prakash, B Tech (Mech), MBA(Fin) , MTech (IIT Delhi)
Computational Fluid Dynamics, Multiphase dynamics Heat exchangers, Turbo machinery Steam generators design, Heat transfer and Radiation 500MW Boiler Computational fluid Dynamics
Job profile: 1988, :` Hindustan Aeronautics limited (design of Aero engines) 1989 -2010: NTPC
Commissioning of coal fired units of capacities 210 MW,500MW, Performance testing of the boilers, turbines and associated auxiliaries, Environment Management systems
2010 : Steag Energy Services
System Technologies, Engineering thermal power plants, O&M Currently: Chief Executive Officer for a Steag O&M Company
Seite 3
STEAG SteagistheGermany'sfifthlargestproducerofelectricity,
Operates15powerplantsat11sitesthroughoutGermany,
Installedgeneratingcapacityofabout8,600MW;eightofthesepowerplantsusehardcoalasprimaryenergysource.
SteagO&MCompanyisaJVof
SteagEnergyServices,India
And
HindujaEnergyIndia
SOMCcurrentlyoperatesthe2X520MWcoalfiredunitsinVishakapatnam
Powerplantefficiency
750MW–Walsum10PowerPlant
EfficiencyandHeatrate
Efficiency: [Electricaloutput/Fuelinput]A500MWcoalfiredpowerplantconsumes300T/hrofcoal(CV4000Kcal/Kg)willhaveanefficiency[500X10^6(W]X3600S)/[300X10^3(Kg)*4000*4180J)]=35.85%Inpowerplantterminology,UnitHeatrateisdefinedastheratioofTurbineheatrateandBoilerefficiency.
SubcriticalandSupercritical
• Subcriticalsteamcycles(Pressure<criticalpressure225bar)haveunitheat
ratesintheorderof2400Kcal/Kwh
• Highertheheatrate,pooreristhecycleinefficiencybecausecoal
consumptionishigh.
• Supercriticalcyclesbecauseofhighersteamparametershaveabetter
cycleefficiencythansubcriticalunits
Rankine Cycle
Tuesday, 8 December 15 Fußzeilentext 8
Lossesinthecycle
1. Boilerefficiency
2. Turbineheatrate
3. Oxygeninfluegas
4. Condenservacuum
5. Demineralizedmakeupconsumption
6. Secondaryfuelconsumption
7. Auxiliarypower
AnalysisofOperatingparametersonPlantefficiency
Effectsof pressure, Superheating, Reheating
Effectsof Condenservacuum Regeneration
AdvancementsinHeatrate
Cycleefficiencies
IfaplantcanoperateideallybetweenthetemperaturelimitsT5andT1,thereis6%lossincycleefficiencybetweenCarnotandRankinecycles
Accurate unit heat rate
• The obstacles to calculating an accurate heat rate for a coal-fired
unit using this method are:
• The difficulty in accurately assessing the quantity of coal
• The inaccuracies of the as-received coal
• Uncertainty associated with measurements made over long periods of
time.
• The use of an average heating value for a fuel whose heating value
may vary widely with different fuel suppliers.
Tuesday, 8 December 15 Fußzeilentext 13
Actualversusdesignedheatrate
CostofHeatratedeviation
• Ifaplant’stargetheatrateis2300Kcal/KWhandtheactualvalueis2350Kcal/kWh,whatistheincreaseinannualfuelcost?
• ChangeinAnnualFuelCost(Rs/yr)=HRD/BE×FC×PLF×UGC×TWhere:
• HRDHeatRateDeviation(netunitorturbinecycleheatrate)
• BE BoilerEfficiency=0.88
• FC FuelCost/1,000,Kcal
• PLF UnitCapacityFactor=0.85
• UGCUnitGrossCapacity=500,000kW
• T= 8760hr/year
• ForaHRDof50Kcal/Kwhthecostis86.5MillionINRfora500MWunit
• [@fuelcostis3600Rs/1000Kg]
Boilerlosses• FoulingofBoilerheatingsurfaces:Affectsheattransfer• Airingress:Disturbsfurnacedraft,fluegasvelocities,dilutes
combustion• HighlevelsofunburntsinAsh:inefficientcombustion,loss
offuelvalue• Poorcoalcalorificvalue:highfuelrequirement,hugewaste
handling• Impropercombustion:metaltemperatureexcursions,
secondaryfires• Boilerscales:InternaltubescalesaffectsHeattransfer,
leadstotubefails• Suboptimizedequipmentoperation:Equipmentoperation
belowdesign• Poordesign:inadequatemargins,qualityofmaterial,
resistancepaths• Poorinsulation:heatradiationloss• Highpressuredrops:heavyloadondraftsystemleadingto
increasedpower
and Environmental Research Center (EERC) have developed anash behavior prediction tool to assess slagging and fouling incoal-fired boilers called AshProSM. The development of thistool combines EERC's coal ash behavior expertise and RMTSmartBurn®'s expertise in combustion, CFD modeling andboiler operation. AshProSM integrates ash behavior modelsincluding ash formation, transport, deposition, and growth withboiler CFD simulations [3]. A unique advantage of AshProSM isthat it can be used to evaluate the localized slagging and foulingproblems that are related to actual operating conditions. There-fore, it can be used to identify the major causes of ash depositionso that measures to reduce the problem can be implemented.
2. Ash behavior models and the integration with CFD
simulations
The inorganic coal components undergo complex physicaland chemical transformations during combustion to producevapors, liquids, and solid phases in the flame. The abundanceand chemical characteristics of these phases depend on howthe inorganic species are associated in the fuel and oncombustion conditions. The partitioning of the inorganiccomponents into the various phases during combustion andgas cooling involves a continuum of complex interrelatedchemical reactions and physical transformations. The
Fig. 2. Deposit thickness (mm) on furnace rear wall close to corner 3 SOFA and furnace wall picture at a similar location.
Fig. 3. Ash impaction (kg/m2–s), deposit thickness (mm), temperature (K), deposit strength (Pa) on the furnace walls.
1036 Z. Ma et al. / Fuel Processing Technology 88 (2007) 1035–1043
Challenges
Airpreheater
IssueswithAirHeater
Thepoorperformanceofairpreheater:higherunitheatrate,deteriorationinboilerefficiency.ThemainproblemofairpreheateristheleakageofairtothefluegassideThehigherashcontentinIndiancoalalsoaddstotheproblemsassociatedwithairpreheater.Airpreheatersaredesignedtomeetperformancerequirementswithconsiderationofhighlyinfluencingparametersviz.heattransfer,leakageandpressuredrop.
SealleaksanderosioninAPH
2
PERFORMANCE IMPROVEMENT IN REGENERATIVE AIR PREHEATERS
SEAL LEAKAGES
Air leaks across radial and by-pass seals to flue gas
side .Leakages are measured by comparing oxygen
content of the flue gas entering and leaving
airpreheater .
This calculated leakage includes leakages through
radial seals on hot and cold end sides together and is
measured as percent of air flow.. Flue gas leakage
across bypass seals is not accounted for.O2 content
does not vary as gases bypass air heater totally and
leave APH without transferring heat to heating
elements and in turn air stream, which result in
increased flue gas temperature at outlet and increased
loading on Electro static precipitators. Similarly air
bypassing APH is not getting heated reducing air
outlet temperature. Heat loss occurred reduces boiler
efficiency. Leakages can be as high as 15 to 20 percent.
And are difficult to measure.
Utmost care needs to be taken while setting bypass
seals. Flexible seals are developed to reduce leakages
through radial seals. Modified `T` bars along with
flexible seals are also developed to reduce leakages
across bypass seals.
High flue gas velocity on outboard side causes heavy
erosion of heating elements at outer baskets.
Comparatively less erosion is observed on inboard side
baskets. Non-uniform distribution of flue gas entering
APH from economizer is the main reason. If coarse fly
ash from economizer hoppers is not evacuated
regularly, heap of ash forms in these hoppers. The
heaps not only affect flue gas distribution but also spill
over to APH causing erosion. Non uniform distribution
of gas also causes erosion of ‘T’ bars, rotor angle,
bypass seals and rear side duct plates from economizer
to APH along with expansion joints.
)9.20()(*100
2
22
outOinOoutOLeakages
��
Erosion pattern
on out board
side of APH
2
PERFORMANCE IMPROVEMENT IN REGENERATIVE AIR PREHEATERS
SEAL LEAKAGES
Air leaks across radial and by-pass seals to flue gas
side .Leakages are measured by comparing oxygen
content of the flue gas entering and leaving
airpreheater .
This calculated leakage includes leakages through
radial seals on hot and cold end sides together and is
measured as percent of air flow.. Flue gas leakage
across bypass seals is not accounted for.O2 content
does not vary as gases bypass air heater totally and
leave APH without transferring heat to heating
elements and in turn air stream, which result in
increased flue gas temperature at outlet and increased
loading on Electro static precipitators. Similarly air
bypassing APH is not getting heated reducing air
outlet temperature. Heat loss occurred reduces boiler
efficiency. Leakages can be as high as 15 to 20 percent.
And are difficult to measure.
Utmost care needs to be taken while setting bypass
seals. Flexible seals are developed to reduce leakages
through radial seals. Modified `T` bars along with
flexible seals are also developed to reduce leakages
across bypass seals.
High flue gas velocity on outboard side causes heavy
erosion of heating elements at outer baskets.
Comparatively less erosion is observed on inboard side
baskets. Non-uniform distribution of flue gas entering
APH from economizer is the main reason. If coarse fly
ash from economizer hoppers is not evacuated
regularly, heap of ash forms in these hoppers. The
heaps not only affect flue gas distribution but also spill
over to APH causing erosion. Non uniform distribution
of gas also causes erosion of ‘T’ bars, rotor angle,
bypass seals and rear side duct plates from economizer
to APH along with expansion joints.
)9.20()(*100
2
22
outOinOoutOLeakages
��
Erosion pattern
on out board
side of APH
Onlineefficiencyanddiagnostics
22
23
24
Condenser
25
26
Air flue gas system 27
Ebsilonmodelling-offline
Improvements in Power Plant Efficiency
• There are a number of specific improvements in power for example: • Cleaning tubes and boilers • maintaining instrumentation • restoring seals • removing deposits on turbine blades • condenser maintenance programs • decreasing excess oxygen to the boiler • Instaling variable speed drives for motors • waste heat utilization for feed water heating
• Installing a online performance diagnostic software
Tuesday, 8 December 15 Fußzeilentext 29
Wecancontribute
• SteagO&MCompanycanhelpyou….
• InOperatingandMaintainingthepowerplants• Efficiencytestingofthepowerplants• OrganizingtheO&Msystems• EnergyAuditingofthepowerplants• Commissioningofthepowerplants• OwnersEngineeringofpowerplants• Supplyonlineefficiencymonitoringsystems• Benchmarkingofoperationsforreducingthecostofgeneration
THANKYOUK . BHANUPRAKASH@STEAG . I N
Top Related