BOILER EFFICIENCY Steam Output Radiation Loss Heat Input

BOILER EFFICIENCY Steam Output Radiation Loss Heat Input Second Pass ESP Furnace Heat Input is Pulverised Coal Heat Output is Superheated Steam

Efficiency Calculations Standard Applied : - ASME Standard PTC 4. 1 Calculation Method : - Loss Method Losses calculated as percentage of INPUT as 100%

Losses in Boilers Heat Input Second Pass Furnace ESP 1) Loss due to dry flue gas = 4. 928%

Losses in Boilers Contd. Second Pass Heat Input Furnace ESP 2) Loss due to Unburnt Carbon = 0. 331%

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%

Losses in Boilers Contd. Second Pass Heat Input ESP Furnace 5) Radiation Losses = 0. 200%

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%

Data required for Boiler Efficiency Calculations Unit load MW FW Flow at Econ inlet T/hr Wet 0 C Dry bulb Temp 0 C Barometric Pressure Temp mm. Hg 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 %

Data required………. 2 Proximate Analysis of Coal Air Dry As fired Moisture % % Ash % % Volatile Matter % % Fixed Carbon % % Gross Cal. Value Kcal/kg Ave FG O 2 APH in Ave FG O 2 APH Out Ave FG CO 2 APH in Ave FG CO 2 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

Calculations Ultimate Analysis As fired Basis 1. Carbon = (Fixed Carbon AD+0. 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 AD+10)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 -(Carbon+Hydrogen+Nitrogen+Ash AD+Moisture AD)* GCV AF/GCV AD 7. Ash = Ash AF and 8. Gross Cal. Value=GCV AF

Calculations …. . Losses Dry Gas Loss = Sensible heat of dry gas*100/(GCV AF*4. 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

CONTROLLABLE LOSSES 1 FOLLOWING LOSSES CAN BE CONTROLLED 1. LOSS DUE TO DRY FLUE GAS THE DESIGNER GIVES THIS LOSS AT THE FLUE GAS 0 APH OUTLET TEMP OF 140 C ANY INCREASE IN THE FGT MORE THAN 1400 C WILL BE RESULTING IN MORE LOSSES. THIS TEMP HAS TO BE CONTROLLED BY PROPER CLEANING OF THE FURNACE

CONTROLLABLE LOSSES 2 a 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%.

CONTROLLABLE LOSSES 2 b 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 O 2 % 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

Losses Calculations Assumptions: - 1. Fly Ash is 80% of Total Ash. 2. Bottom Ash is 20% of Total Ash 3. Sulphur is 0. 4% in Coal

DATA REQUIRED Fuel Properties Proximate Analysis of Coal Air Dry Basis As Fired basis Moisture % Ash % Volatile Matter % Fixed Carbon % Gross Cal. Value %

Data Required contd. Unit load MW FW Flow at Econ inlet T/hr Wet bulb Temp 0 C Dry Bulb. Temp 0 C Barometric Pressure Total Coal Flow T/hr Unburnt Carbon in BA % Unburnt Carbon in FA %

Data Required Contd. ** Ave FG O 2 APH in ** Ave FG CO 2 APH in ** Ave FG CO APH in ** Ave FG O 2 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

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 %

GCV Calculations for Coal Contd. 1) Useful Heat Value = 8900 – 138(A%+M%) 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) 5) Net Calorific Value Kcal/kg = [GCV] – 10. 02 M% Kcal/kg

Calculations Weight of Dry Gas = (Ca+S/2. 67 -100*U)/(12*CO 2 out) 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/100*Cfa + Pba/100*Cba U = Carbon in ash / kg of fuel=A/100*Cash/(100 -Cash) CO 2 Out = Avg. CO 2 Flue Gas -APH Out Sensible Heat Dry Gas = Wd*30. 6(Tgo-Trai)