Presentation Boiler performance

1. POWER
Boiler Performance & Life
Extension
By – Keyur Patel. (Operation Department)

2. Topics covered under BHEL program are following
• Boiler Performance & design.
• Life Assessment of Boilers.
• Combustion Optimization & performance.
• Replication & Metallurgical Evolution.
• Water Chemistry.
• O&M of C&I – on Boiler.
• O&M of Valves.
• Field Problems & case Studies in Boilers.
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3. 22 August 2013 Operation Department 3
Boiler Performance & design.

4. COAL PROPERTIES AFFECTING
BOILER DESIGN
• TYPE OF COAL ( ANTHRACITE, BITUMINOUS,
LIGNITE)
• HIGHER HEATING VALUE
• VOLATILE MATTER
• MOISTURE CONTENT
• ASH CONTENT
• ASH CHARACTERISTICS
• HARD GROVE INDEX ( HGI )
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5. CHARACTERISTICS OF TYPICAL
INDIAN COAL
• HIGH ASH (35 – 50%)
• HIGHLY ABRASIVE
• MEDIUM MOISTURE (10 – 15%)
• MEDIUM VOLATILE MATTER (18 – 24%)
• LOW HEATING VALUE (HHV kcal/kg) (3000 – 3500)
• LOW SULPHUR (0.2 – 0.5%)
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6. FURNACE SELECTION CRITERIA
• NHI / PA
• NHI / EPRS
• Q FIRED / VOLUME
• BURNER ZONE HEAT RELEASE RATE
• FURNACE RESIDENCE TIME
• DISTANCE BETWEEN FURNACE BOTTOM-HOPPER &
LOWER MOST FUEL NOZZLE
• DISTANCE BETWEEN UPPER MOST FUEL - NOZZLE &
BOTTOM OF SH
• FURNACE OUTLET TEMPERATURE
• ASPECT RATIO
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7. SELECTION OF AUXILIARIES
• AIRHEATERS
• FANS
• MILLS
• ELECTROSTATIC PRECIPITATOR
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8. FUEL QUALITY AFFECTING THE
PERFORMANCE
• SLAGGING
• SH / RH SPRAY VARIATION
• FLUE GAS TEMPERATURE LEAVING BOILER
• MILL LOADING
• AUX .POWER CONSUMPTION
• BOILER EFFICIENCY
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9. DESIGN CONSIDERATIONS FOR
INDIAN COALS* BOILERS:
• CONSERVATIVE FURNACE HEAT LOADINGS
• LOWER FLUE GAS VELOCITY OVER TUBE BANKS
• PLAIN TUBE IN – LINE ARRANGEMENT OF HEAT TRANSFER SURFACE
-OPTIMUM END GAPS TO AVOID PREFERENTIAL GAS FLOW
-EROSION SHIELDS / CASSETTE BAFFLES
-EROSION ALLOWANCE FOR LEADING TUBES
-CAST STEEL PF BENDS & CERAMIC LINEDPF BENDS
* BOILER AUXILIARIES
-IMPROVED SEALING ARRANGEMENT IN AIRHEATERS
-EXTENDED TUBE-TUBULAR APH
-LOW SPEED RADIAL ID FANS
-LINED IMPELLERS OF RADIAL FANS
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10. 22 August 2013 Operation Department 10
Life Assessment of Boilers (RLA).

11. RLA- A Predictive tool for Better unit
Availability & Reliability
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• As per regulation 391 A of IBR,1950
• Utility or Industrial Boilers operating at a Temp. of 400°C of above
in the creep range
• To be non-destructively tested after 1,00,000 hours of operation for
Assessment of Remnant Life.
• If results are acceptable CIB will issue a certificate for
> extending the life for further period of 10 years
> or a less period as recommended by RLA organization

12. RLA in BHEL
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13. RLA Study Aims At
• Evaluation of present condition of pressure parts
& piping
• Avoiding premature pressure parts failures and
associated unforeseen outages
• Identification of problem areas
• Analysis of root cause of problems
• Estimation of balance life of pressure parts
• Providing technically sound and viable proposal
for implementation
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14. Distribution in SG pressure parts
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15. Stages of Residual Life Assessment
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16. Various damage mechanisms and
suitable NDE methods for RLA
Damage Mechanism NDE Methods for detection
Erosion Visual Examination (VE), Ultrasonic Thickness
Survey
Blockade in water circuit Fibroscopy
Welding defects Ultrasonic Test (UT), Magnetic Particle Test (MPT),
Dye Penetrant Test (DPT), Radiographic Test (RT)
Creep In-situ Metallography, Hardness Measurement
Oxide Scale growth Ultrasonic Test (UT)
Thermal fatigue crack detection and
sizing
Ultrasonic Time of Flight Diffraction (TOFD)
inspection, potential drop technique
Short Term overheating In-situ Metallography, Hardness Measurement
Swelling Dimensional Measurement (OD)
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17. 22 August 2013 Operation Department 17
Combustion Optimization & performance.

18. Measures to improve Plant Efficiency
Boiler side:
1. Minimum flue gas temperature at AH outlet
2. Minimum excess air at AH outlet
3. Minimum un-burnt Carbon loss
4. Minimum RH spray Minimum SH spray
5. Reduced Auxiliary Power Consumption
Turbine Side:
1. Higher steam parameters ( MS Pressure & SHO/RHO Steam Temp)
2. Increasing feed water temperature with Enhanced Regenerative
feed heating.
3. Improvement in condenser vacuum
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19. Factors Influencing Various Losses
Losses Factors
Dry Gas Loss Flue Gas Temperature
Excess Air Level In Flue Gas
Fuel Analysis
Loss Due To Moisture Formed From
hydrogen in Fuel
Hydrogen Content In Fuel
Flue Gas Temperature
Fuel Analysis
Loss Due To Fuel Moisture Moisture Content In Fuel
Flue Gas Temperature
Loss Due To Air Moisture Humidity Of Combustion Air
Excess Air Level
Flue Gas Temperature
Radiation & Convection Loss Insulation Of Boiler
Mill Reject Loss Reject Rate
CV Of Reject
Unburnt Carbon Loss In Ash Unburnt Carbon In Fly / Bottom Ash
Fuel Analysis
Sensible Heat Loss In Ash Ash Temperature
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20. Optimization of Boiler Efficiency
HHV ↑ All Losses ↓
FG APH out Temp ↑ Dry gas, Sensible heat in Ash, H2, Fuel
and Air Moisture Loss ↑
Excess air ↑ Dry gas & Air Moisture Loss ↑
Unburnt carbon loss ↓
Fuel Moisture ↑ Fuel Moisture Loss ↑
Air Moisture ↑ Air Moisture Loss ↑
H2 in Fuel ↑ H2 Loss ↑
Mill reject rate or GCV ↑ Mill reject Loss ↑
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Hence Major parameters to be looked into for Better Efficiency are
1. FG Temp
2. Excess air Level
3. Mill reject rate and
4. Unburnt carbon in ash
Control / Optimization of other parameters (i.e GCV, H2, Fuel moisture and Air Moisture)
are not possible.

21. Boiler Losses - operator controllable
• Efficiency
– Dry gas Loss
• Excess air
• Exit gas temperature
– Air ingress
– Fouling
– Tempering air
– Carbon loss
• Excess air
• Air regime
• Mill fine ness
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22. UNIT-1 PG TEST DATA
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Operation Department
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Heat Losses Unit
100% TMCR
269.95 MW
80% Load
Sliding Pr.
224.27MW
80% Load
Constant Pr.
222.75 MW
60% Load
Sliding Pr.
172.78 MW
60% Load
Constant Pr.
171.45 MW
Dry Gas Loss % 5.95 4.49 4.54 4.46 5.11
Loss due to Unburnt Carbon % 0.69 0.64 0.84 0.79 0.69
Loss due to moisture in fuel (H2O in fuel) % 1.67 1.81 1.60 1.66 1.66
Loss due to Hydrogen in Fuel (H2 in Fuel) % 5.31 4.12 4.27 4.58 5.29
Loss due to Carbon monoxide % 0.07 0.05 0.05 0.05 0.06
Loss due to moisture in air (H2O in Air) % 0.37 0.36 0.32 0.33 0.33
Radiation Loss % 0.20 0.20 0.20 0.20 0.20
Sensible Heat Loss % 0.36 0.53 0.42 0.47 0.36
Coal Mill Reject Loss % 0.03 0.03 0.03 0.04 0.04
Manufacturer Margin % 0.50 0.50 0.50 0.50 0.50
Total % 15.15 12.73 12.78 13.09 14.25
Heat Credit due to Coal Mill Power % 0.59 0.62 0.65 0.88 0.87
BOILER EFFICIENCY % 85.44 87.90 87.87 87.79 86.62
DESCRIPTION Unit
100% TMCR
216MW
80% Load
Sliding Pr.
224.27MW
80% Load
Constant Pr.
222.75MW
60% Load
Sliding Pr.
172.78MW
60% Load
Constant Pr.
171.45MW
Heat In Put To Turbine Cycle Kcal/Hr 529,259,752.16 450,247,808.16 444,379,675.70 357,788,998.87 352,103,308.21
Turbineheat Rate Kcal/Kwh 1960.58 2007.61 1994.97 2070.78 2053.68
Gross Heat-Rate by Loss Method Kcal/Kwh 2294.66 2284.04 2270.31 2358.88 2370.88
Efficiency HPT Ehpt (%) 103.90 97.18 100.71 99.65 107.20
BOILER DATA
TURBINE DATA

23. Combustion optimization
• Sec. Air distribution at required elevation is very important
• Avoid / reduce all unwanted sec. Air at any location And divert
them to other needy elevation.
• Keep mill air flow just above settling velocity. Do pitot traverse to
check primary air flow. Keep reducing primary air - settling start.
Slight furnace disturbance starts. Increase by primary air 1-2 t/hr
• Keep total air flow - 20% excess air @ eco out
• Close all fuel air dampers if VM less than 20 -22% Look flame front -
decide for higher VM coal
• Keep wind box pr. 100 - 150 mm – better distribution Across
elevation.
• Fuel distribution.
• Smart wall blowing system.
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24. Wind Box Damper Setting for Completion of Combustion
and to reduce unburnt in bottom / fly Ash Collection
Training BHEL Actual
Keep opening of AA damper (Manual Damper) in the range of 40 – 50 %
always irrespective of the mills in service. Do not close it
Relation with WB DP 5% to 15%
Almost Close the FAD of the operating elevation for the VM is less than 20
% (Every 1% VM increase, open FAD by 2-3% approx.)
FUEL DAMPER OPENING (%)/FEEDER RATE
(0/0, 5/25, 20/60, 20/100)
19.56 to 20.00
Close the FAD & AAD of non-working elevation always. closed closed
Keep Wind box pressure around 80 – 100 mmWC.
Load/WB DP (0/40, 30/40,
45/60,60/100,100/100)
DPT-1 93.26 mmWC
DPT-2 100.14mmWC
To get better flame intensity and stability, optimum windbox Dp and
reducing
the opening of FAD is suggested.
Check and ensure the same position of SADC’s elevation wise in all the
corners. Ensure to get equal Wind box Dp in left and right side.
Opening of OFA/top AAD of non working EL. – Depends on Unburnt Fly Ash
& SH, RH Temp/Spray
@ 50% Load OFA Lower 0% @75% Load
OFA-Lower 100%/OFA upper (0)
@100% Load OFA upper-100%
0%
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26. Case Study - 1
• Problem:
– Heavy clinkering build up to S-panel /Bottom of burner
reported from many boilers
• Investigations:
• Poor mill fineness (50% through 200 mesh)
• Non-working of SADC as per control
• Poor coal quality – usage of ground stock
• Non- working of wall blowers
• Improper evacuation of bottom ash
• Solution: After taking above corrective actions no
further problems faced.
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27. 22 August 2013 Operation Department 27
O&M of Valves.

28. Fundamentals
Valve - Valves are mechanical devices designed to direct, allow,
disallow, mix or regulate the pressure, flow or temperature of a
process fluid. The basic function of a valve is to “Isolate Flow” as the
Value Engineering experts put it in Verb-Noun form.
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1. FORGED VALVES : Valve sizes of 2” & below are made of forgings.
2. CAST VALVES : Valve sizes of 2” & above are made of castings

29. SAFETY & SAFETY RELIEF VALVES
Definition- Safety and Safety Relief Valves (SV & SRV) are automatic
pressure relieving devices used for relieving the excessive pressure
build up in Pressure Vessels.
CLASSIFICATION OF PRESSURE RELIEF VALVES :
(a) Safety Valves (b) Relief Valves (c) Safety Relief Valves.
CODES GOVERNING SAFETY VALVES :
(a) Indian Boiler Regulations (IBR),
(b) ASME Section I for Power Boilers,
(c) ASME Section VIII for Unfired pressure vessels,
(d) API Standards 526 & 527,
(e) BS 6759 etc.
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30. 22 August 2013 30

31. Questions ?
&
Thank You
Special thanks to Planning Dept. for wonderful “PPT Theme”
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32. My Questions
• FCS regulation.
• PA Fan minimum loading (Settling velocity in mill)
• SA optimization by knowing excess air with CO (Hit
n trial)
• Tempering Design operation
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