BOILER EFFICIENCY

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BOILER EFFICIENCY
Steam Output
Radiation Loss
Second Pass
Heat Input
ESP
Furnace
Heat Input is Pulverised Coal Heat Output is
Superheated Steam
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Efficiency Calculations
Standard Applied - ASME Standard PTC
4.1 Calculation Method - Loss Method Losses
calculated as percentage of INPUT as 100
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Losses in Boilers
Second Pass
Heat Input
Furnace
ESP
1) Loss due to dry flue gas 4.928    
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Losses in Boilers Contd.
Second Pass
Heat Input
ESP
Furnace
2) Loss due to Unburnt Carbon    0.331
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Losses in Boilers Contd.
Second Pass
Heat Input
ESP
Furnace
3) Due to Sen. Heat of Bottom Ash       
0.071 4) Due to Sen. Heat of Fly Ash     
  0.102
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Losses in Boilers Contd.
Second Pass
Heat Input
ESP
Furnace
5) Radiation Losses                 
 0.200
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Losses Related to Coal Ambient Air Quality
6) Loss due to moisture in Fuel   1.263 7)
Loss due to Hydrogen in Fuel   5.537 8) Loss
due to Moisture in Air      0.074 9)
Unaccounted Losses   1.327     Total
Losses                     13.83
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Data required for Boiler Efficiency Calculations
Unit load MW FW Flow at Econ
inlet T/hr Wet bulb Temp 0C Dry
bulb Temp 0C Barometric Pressure mmHg Total
Coal Flow T/hr Unburnt C in BA Unburnt C
in FA Radiation Unaccounted Losses
Fly ash to Total Ash
Bottom ash to Total ash
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Data required.2
Proximate Analysis of Coal Air Dry
As fired Moisture Ash
Volatile Matter
Fixed Carbon Gross Cal.
Value Kcal/kg
Kcal/kg
Ave FG O2 APH in Ave FG O2 APH Out Ave
FG CO2 APH in Ave FG CO2 APH Out Ave FG CO
APH in Ave FG CO APH Out Ave. FG Temp APH
in Ave. FG Temp APH Out Air to APH in Air
APH out Total Primary Flow Total Air
Flow L Total Air Flow R
Design Ambient / Ref air Temp
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Calculations
Ultimate Analysis As fired Basis 1.
Carbon (Fixed Carbon AD0.9(Vol Matter
AD-14)) GCV AF/GCV AD 2. Sulphur
0.4 GCV AF/GCV AD 3. Hydrogen Vol.Matter
AD(7.35/(Vol Matter AD10)-
0.013) GCV AF/GCV AD 4. Moisture Moisture
AF 5. Nitrogen (2.1-0.012 Vol.Matter AD) GCV
AF/GCV AD 6. Oxygen 100-(CarbonHydrogenNitroge
nAsh ADMoisture AD) GCV AF/GCV AD 7. Ash
Ash AF and 8. Gross Cal. ValueGCV AF
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Calculations .. Losses
Dry Gas Loss Sensible heat of dry gas100/(GCV
AF4.186) Carbon in fuel Sulfur in
fuel Carbon in ash / kg of fuel kg/kg
coal Specific Heat of Gas kg/kg C Avg. Flue gas
temp - APH Out 0C Unburned C in Ash Pfa/100Cfa
Pba/100Cba C in Ash / Kg of coal
A/100Cash/(100-Cash) kg     Total air Flow
AB Thr Ratio SA Flow to Total Air Flow -
Fsa/Fta Ratio PA Flow to Total Air Flow
Fpa/Fta Weighted Temp Air In
TsaiRsaTpaiRpa 0CWeighted Temp Air Out
TsaoRsaTpaoRpa 0C    Avg. Flue Gas CO2 -APH
Out Gross CV kcal/kg Weight of Dry Gas
(CaS/2.67-100U)/(12CO2out) kg/kg coal Sensible
Heat Dry Gas Wd30.6(Tgo-Trai) kJ/kg
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CONTROLLABLE LOSSES 1
FOLLOWING LOSSES CAN BE CONTROLLED
1. LOSS DUE TO DRY FLUE GAS
THE DESIGNER GIVES THIS LOSS AT THE FLUE GAS APH
OUTLET TEMP OF 1400C
ANY INCREASE IN THE FGT MORE THAN 1400C WILL BE
RESULTING IN MORE LOSSES. THIS TEMP HAS TO BE
CONTROLLED BY PROPER CLEANING OF THE FURNACE
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CONTROLLABLE LOSSES 2a
LOSSES DUE TO THE UNBURNT COAL IN BOTTOM AND FLY
ASH.
LOSS DUE TO UNBURNT IN BOTTOM ASH
THE DESIGNER GIVES THIS AGE AS MAX 4.8 ANY
INCREASE IN THIS PERCENTAGE BEYOND THIS WILL
RESULT IN MORE LOSSES
IF UNBURNT IN BOTTOM ASH IS MORE, THE CULPRIT IS
THE COAL MILL, CHECK THE FINENESS OF PULVERISED
COAL. CHECK THE RETENTION ON 50 MESH. IT SHALL
NOT EXCEED 1.
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CONTROLLABLE LOSSES 2b
CHECK THE UNBURNT IN FLY ASH SAMPLE TAKEN FROM
THE FIRST HOPPER OF ESP/BF
AS PER THE DESIGNER IT SHALL NOT EXCEED 0.8.
IF UNBURNT IN FLY ASH EXCEEDS 0.8 IT INDICATES
INCOMPLETE COMBUSTION DUE TO LESS AMOUNT OF AIR
CHECK FOR O2 AT THE APH FG INLET FOR 2.8,
INCREASE IF NECESSORY TO 3.2. AGAIN CHECK FOR
UNBURNTS IN FLY ASH. SIMULTANIOUSLY CHECK FOR AIR
LEAKAGES/INGRESS IN THE SECOND PASS
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Losses Calculations

• Assumptions-
• Fly Ash is 80 of Total Ash.
• Bottom Ash is 20 of Total Ash
• Sulphur is 0.4 in Coal

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DATA REQUIRED
Fuel Properties Proximate Analysis of Coal Air
Dry Basis As Fired basis Moisture
Moisture Ash Ash Volatile
Matter Volatile Matter Fixed Carbon
Fixed Carbon Gross Cal. Value Gross
Cal. Value
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Data Required contd.
Unit load MW FW Flow at Econ
inlet T/hr Wet bulb Temp 0C Dry BulbTemp
0C Barometric Pressure Total Coal
Flow T/hr Unburnt Carbon in BA Unburnt
Carbon in FA
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Data Required Contd.
Ave FG O2 APH in Ave FG CO2 APH in
Ave FG CO APH in Ave FG O2 APH Out Ave
FG CO2 APH Out Ave FG CO APH Out Air to
APH in Temp Air APH out Temp Total Air
Flow L Total Air Flow R Ave. FG Temp
APH in Ave. FG Temp APH Out Total
Primary Air Flow
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GCV Calculations for Coal
Calculations of GCV  As fired Basis Coal sample
is taken as received basis, heated for
calculation of A) Total Moisture content
TM  Air Dry Basis The sample is air dried for
removal of surface moisture and burned completely
for A) Inherent moisture content M B) Ash
percentage A
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GCV Calculations for Coal Contd.
1) Useful Heat Value 8900 138(AM)
kcal/kg 2) Gross Calorific Value (UHV 3645
75.4 M)/1.466 (Air Dry Basis)
Kcal/kg 3) Ash (As fired basis) A (100 -
TM)/(100 M) 4) Gross Calorific Value
GCVAD (100 - TM)/(100 M) (As fired
Basis) Kcal/kg 5) Net Calorific Value
GCV 10.02M Kcal/kg
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Calculations
Weight of Dry Gas (CaS/2.67-100U)/(12CO2out)
Ca Carbon in fuel (Ultimate Analysis as
Fired) S Sulfur in fuel (Ultimate Analysis as
Fired) A of Ash in fuel (Ultimate Analysis as
Fired) Unburned C in Ash Pfa/100Cfa
Pba/100Cba U Carbon in ash / kg of
fuelA/100Cash/(100-Cash) CO2 Out Avg. CO2
Flue Gas -APH Out Sensible Heat Dry Gas
Wd30.6(Tgo-Trai)