Presented at National Boiler Workshop 2015 - Presented by STEAG

1. Online efficiency and diagnostics
of a coal fired Boiler

2. 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

3. Seite
3
STEAG
Steag is the Germany's fifth largest producer of electricity,
Operates15 power plants at 11 sites throughout Germany,
Installed generating capacity of about 8,600 MW; eight of these
power plants use hard coal as primary energy source.
Steag O&M Company is a JV of
Steag Energy Services,India
And
Hinduja Energy India
SOMC currently operates the 2X520MW coal fired units in
Vishakapatnam

4. Power plant efficiency

5. 750 MW – Walsum 10 Power Plant

6. Efficiency and Heat rate
Efficiency: [Electrical output/Fuel input]
A 500 MW coal fired power plant consumes 300T/hr of coal (CV 4000Kcal/Kg) will have
an efficiency
[500 X 10^6(W]X3600 S) / [300X10^3(Kg)*4000*4180 J)]
= 35.85%
In power plant terminology, Unit Heat rate is defined as the ratio of Turbine heat rate
and Boiler efficiency.

7. Sub critical and Super critical
• Subcritical steam cycles(Pressure < critical pressure 225 bar) have unit heat
rates in the order of 2400 Kcal/Kwh
• Higher the heat rate, poorer is the cycle in efficiency because coal
consumption is high.
• Super critical cycles because of higher steam parameters have a better
cycle efficiency than sub critical units

8. Rankine Cycle
Tuesday, 8 December 15 Fußzeilentext 8

9. Losses in the cycle
1. Boiler efficiency
2. Turbine heat rate
3. Oxygen in flue gas
4. Condenser vacuum
5. Demineralized make up
consumption
6. Secondary fuel consumption
7. Auxiliary power

10. Analysis of Operating parameters on Plant
efficiency
Effects of pressure, Superheating, Reheating
Effects of Condenser vacuum Regeneration

11. Advancements in Heat rate

12. Cycle efficiencies
If a plant can
operate ideally
between the
temperature limits
T5 and T1, there is 6%
loss in cycle
efficiency between
Carnot and Rankine
cycles

13. 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

14. Actual versus designed heat rate

15. Cost of Heat rate deviation
• If a plant’s target heat rate is 2300 Kcal/KWh and the actual value is 2350Kcal/
kWh, what is the increase in annual fuel cost?
• Change in Annual Fuel Cost (Rs/yr) = HRD/BE × FC × PLF × UGC × T
Where:
• HRD Heat Rate Deviation (net unit or turbine cycle heat rate)
• BE Boiler Efficiency = 0.88
• FC Fuel Cost/1,000,Kcal
• PLF Unit Capacity Factor = 0.85
• UGC Unit Gross Capacity = 500,000 kW
• T = 8760 hr/year
• For a HRD of 50 Kcal/Kwh the cost is 86.5Million INR for a 500MW unit
• [@fuel cost is 3600 Rs/1000 Kg]

16. Boiler losses
• Fouling of Boiler heating surfaces: Affects heat transfer
• Air ingress: Disturbs furnace draft,flue gas velocities,dilutes
combustion
• High levels of unburnts in Ash: inefficient combustion,loss
of fuel value
• Poor coal calorific value: high fuel requirement, huge waste
handling
• Improper combustion: metal temperature excursions,
secondary fires
• Boiler scales: Internal tube scales affects Heat transfer,
leads to tube fails
• Sub optimized equipment operation: Equipment operation
below design
• Poor design: inadequate margins, quality of material,
resistance paths
• Poor insulation: heat radiation loss
• High pressure drops: heavy load on draft system leading to
increased power
nology 88 (2007) 1035–1043

17. Challenges

18. Air preheater

19. Issues with Air Heater
The poor performance of air
preheater :higher unit heat rate,
deterioration in boiler efficiency.
The main problem of air preheater is
the leakage of air to the flue gas side
The higher ash content in Indian coal
also adds to the problems associated
with air preheater.
Air preheaters are designed to meet
performance requirements with
consideration of highly influencing
parameters viz. heat transfer,
leakage and pressure drop.

20. Seal leaks and erosion in APH
of the flue gas entering and leaving
ater .
culated leakage includes leakages through
flexible seals are also d
across bypass seals.
High flue gas velocity on
erosion of heating el
Comparatively less erosio
baskets. Non-uniform dis
APH from economizer is
ash from economizer
regularly, heap of ash f
heaps not only affect flue
over to APH causing eros
of gas also causes erosio
bypass seals and rear side
)9.20(
)(*100
2
22
outO
inOoutO
Leakages
udes leakages through
nd sides together and is
low.. Flue gas leakage
counted for.O2 content
s air heater totally and
rring heat to heating
ream, which result in
at outlet and increased
cipitators. Similarly air
ng heated reducing air
occurred reduces boiler
high as 15 to 20 percent.
n while setting bypass
heaps not only affect flue gas distribution but also spi
over to APH causing erosion. Non uniform distributio
of gas also causes erosion of ‘T’ bars, rotor angl
bypass seals and rear side duct plates from economize
to APH along with expansion joints.
Erosion pattern
on out board
side of APH

21. Online efficiency and diagnostics

22. 22

23. 23

24. 24

25. Condenser 25

26. 26

27. Air flue gas system
27

28. Ebsilon modelling -offline

29. 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

30. We can contribute
• Steag O&M Company can help you….
• In Operating and Maintaining the power plants
• Efficiency testing of the power plants
• Organizing the O&M systems
• Energy Auditing of the power plants
• Commissioning of the power plants
• Owners Engineering of power plants
• Supply online efficiency monitoring systems
• Bench marking of operations for reducing the cost of generation

31. THANK YOU
K . B H A N U P R A K A S H @ S T E A G . I N