1. Welcome

2. Combustion Optimization

3. Emerging Market Requirements
Higher Availability & Reliability
Highest Plant efficiency
Lower Heat Rate
Minimum Auxiliary Power Consumption
Ability to operate under adverse grid conditions/fluctuation in demand
Minimum emission of Pollutants

4. Measures to improve Plant Efficiency
Boiler side:
Minimum flue gas temperature at AH outlet
Minimum excess air at AH outlet
Minimum un-burnt Carbon loss
Minimum RH spray
Minimum SH spray
Reduced Auxiliary Power Consumption

5. Measures to improve Plant Efficiency …
Turbine side measures
Higher steam parameters
( MS Pressure & SHO/RHO Steam Temp).
Adoption of double reheat cycle
Increasing feed water temperature with Enhanced Regenerative feed heating
Increase in condenser vacuum

6. 2a. Boiler - Various Losses
By Gas Dry Gas Loss
Loss due to Moisture in Gas
Due to Fuel Moisture
Due to moisture formed by H2 in fuel
Due to air moisture
By Ash Unburnt carbon Loss
Sensible heat loss in Fly ash
Sensible heat loss in Bottom ash
Other Loss Carbon monoxide Loss
Radiation Loss
Heat loss through Mill rejects

7. Factors Influencing Various LossesNo
Loss
Factor 1
Dry Gas Loss
Flue Gas Temperature, Excess Air & Fuel 2
Unburnt Carbon Loss In Ash
Ash in Fuel & Unburnt Carbon In Fly / Bottom Ash 3
Mill Reject Loss
Reject Rate & CV Of Reject 4
Due to Moisture formed from Hydrogen
Hydrogen Content In Fuel & Flue Gas Temperature 5
Due to Fuel Moisture
Moisture Content In Fuel & Flue Gas Temperature 6
Due to Air Moisture
Humidity Of Combustion Air, Excess Air Level & Flue Gas Temperature 7
Radiation & Convection Loss
Insulation Of Boiler 8
Sensible Heat Loss In Ash
Ash Temperature

8. Methods to reduce unburnt carbon loss
Ensure consistent mill fineness - +50, - 200
Good burner maintenance
Proper secondary air adjustment - SADC
Reduce PA air to the minimum possible – min PA velocity variation
Cut out oil support at higher loads where coal flame is stable as oil preferentially deplete o2 in the area and reduces ‘o2 ‘ for coal particles to burn
Check coal property and tune combustion
Keep boiler heat transfer surface clean so that losses can be reduced thus reducing the coal input

9. Methods to reduce dry gas loss
Correct excess air
High mill outlet temp.
Better combustion – combustion tuning
Arrest air ingress
Air heater performance – leakage , proper elements
Cleanliness of the heat transfer surfaces

10. Optimization of Boiler Efficiency1
HHV 
All Losses  2
FG APH out Temp 
Dry gas, Sensible heat in Ash, H2, Fuel and Air Moisture Loss  3
Excess air 
Dry gas, Unburnt & Air Moisture Loss  4
Fuel Moisture 
Fuel Moisture Loss  5
Air Moisture 
Air Moisture Loss  6
H2 in Fuel 
H2 Loss  7
Mill reject rate or GCV 
Mill reject Loss 
The Major parameters to be looked into for Better Efficiency:
FG Temp
Excess air Level
Mill reject rate and
Unburnt carbon in ash
Control / Optimization of other parameters (i.e GCV, H2, Fuel moisture and Air Moisture) are not possible.

11. Major reasons for increase in APC
Operation of unit with higher excess air
Air heater leakage
Higher PA fan outlet pressure
High mill fineness, more no. of mills
Air ingress into boiler
Pluggage in line / ducting
Partialy blocked APH

12. Sources of air ingress Furnace roof Expansion joints Air heaters Ducts
Esp hoppers
Peep holes
Manholes
Furnace bottom

13. Factors affecting APC - a summary
FACTORS AFFECTING AUXILIARY POWER
ID FANS
AH LEAK
GAS TEMPERATURE
DUCT LEAKAGES
EXCESS AIR
LOAD/ PLANT HEAT RATE
DRAUGHT LOSS
AH CHOKING
FD FANS
WIND BOX PR.
PRESSURE LOSS
SCAPH CHOKING
PA FANS
AH LEAKAGE
PA HEADER PR.
MILL AIR FLOW
MILL
COAL QTY.
GCV
COAL
MOISTURE
HGI
COAL FINENESS
MILL CONDITION

14. Capacity Reduction in a Boiler
Fuel input
Low cv coal
Milling capacity
Grinding capacity
Drying capacity
Carrying capacity
Drive capacity
Draught system
ID fan limitations
Pressure drops high
AH choking
Chimney back pressure high
High volume
AH leakages
Duct leakages
High gas temperatures
Worn out impellers
Metal temperatures high
High spray requirements
Fouling of surfaces

15. CASE STUDIES

16. Case Study-1
Problem:
Heavy clinkering build up upto 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.

17. Case Study-2 Problem: Frequent choking of coal pipe
Investigations: Clean air flow test
Checking of orifice
Calibration of coal flow/air flow -check
Foreign material entrapped in classifier ( cloth)
Solution: Problem resolved after removal of foreign material from classifier.

18. THANK YOU