1. ENERGY audit OF COMBUSTION SYSTEMS
P M V Subbarao
Professor
Mechanical Engineering Department
Detailing of Losses and Causes …..

2. Typical Layout of A Coal Fired Furnace
For Adiabatic Furnace
Hchimney
Tgas
pA = pfan.f
Tatm B B A
pB = pfan,s

3. Typical Layout of A Coal Fired Furnace
For A Furnace generating Steam
Hchimney
Tgas
pA = pfan.f
pB = pfan,s
Tatm B B A

4. Energy Potential of Post Combustion Gases
Total Thermal Power of post combustion gases:
Thermal Power of Chimney inlet gases:
Total Thermal Power of post gases available for steam production:
Rate of steam production:

5. Specific Enthalpy Increase due to Generate Superheated Steam3 5 2s 2f 4 2 1 6 s

6. Sankey Diagram for A Coal Fired Furnace
Heat gained by boiling water
40%
Loss due to moisture in air.
Loss due to moisture in fuel.
Loss due to combustion generated moisture.
Dry Exhaust Gas Losses
~ 4.5%
Fuel Energy
100%
Hot gas
Heat gained by superheater & reheater
40%
Heat gained by economizer 6%
Heat gained by air preheater 6%
Flue gas
Heat loss from furnace surface.
Unburned carbon losses.
Incomplete combustion losses.
Loss due to hot ash.

7. Air & Gas Path in A Coal Furnace

8. Distributed Air Supply Systems

9. Paths of Steam and Gas
Drum
Water walls
Economizer

10. Thermal Structure of A Boiler Furnace
DPNL SH
Platen SHTR R H T
LTSH
Economiser
APH ESP ID Fan
drum
Furnace
BCW
pump
Bottom ash
stack
screen
tubes

11. Dry Exhaust Gas Losses
As gasses are leaving at temperature higher than ambient temperature.
For 100 kg of fuel.
QDEGL = S n fluegas Dhfluegas
QDEGL = n CO2 DhCO2 + n CO DhCO + n O2 DhO2 + n N2 DhN2 + n SO2 DhSO2 kJ.
For any gas per unit mass flow rate
Approximate method:
Total number of moles of dry exhaust gas nex.gas = P+R+T+U+V
QDEGL = nex. Gas Cp,exgas (Tex.gas - Tatm)
Cp.exgas = 30.6 kJ/kmol. K
Typical value of DEGL ~ 4.5%

12. Unburned carbon losses.
For 100 kg of fuel
QUCL = nc * MC * Calorific Value of Carbon : kJ
QUCL = nc * 12 * kJ.
Incomplete combustion losses
For 100 kg of fuel:
QICL = nCO * MCO * CV of CO. kJ.
QICL = nCO* 28 * kJ.

13. Loss due to moisture in Combustion air
For 100 kg of fuel:
QMCAL = e 4.76 (X+Y/2+Z-K/2) * 29.9 * w * Csteam * (Tg – Tamb) kJ
Where w is absolute or specific humidity : kg of moisture per kg of dry air.
Csteam is the specific heat of steam at constant pressure : 1.88 kJ/kg C.
Tg is the temperature of exhaust gas.

14. Losses due to moisture in fuel & combustion generated moisture.
For 100 kg of fuel:
QML = ( M +9* Y) { Csteam * (Tg – Tamb) } kJ.
M is the moisture content in the fuel, %.
Y is the combustible hydrogen atoms in the fuel.

15. Loss due to hot ash or Slag
For 100 kg of fuel
QASL = A * Cp,ash * ∆Tash
Where Cp.ash, is the specific heat of ash, 0.5 – 0.6 kJ/kg K.
Tash is the temperature of the ash or slag.
Tash = Varies from 300 to 800 oC

16. Heat loss from furnace surface
Rate of Heat Loss due to Surface Radiation and Convection.
QRCL = As ( hs) (Tsurface - Tamb) kW
As = Total surface area, m2
hs = Surface heat transfer coefficient.
For 100 kg of fuel:
Rate of heat loss/fuel flow rate * 100

17. A Graphic Model for Radiation & Unaccounted Loss

18. Minimization of Energy Losses thru Control of Excess Air

19. Losses due to Fuel Quality
Fuel Samples

20. Selection of Optimal air for Best Performance
% of Excess Air

21. Selection of Optimal air for Eco-Friendliness

22. Learning of Impact of Excess Air

23. Holistic Combustion Optimization Method
% of Excess Air

24. Methods to Apply the Machine Learning

25. Performance Analysis of Internal Combustion Systems

26. Sankey Diagram for Spark Ignition Reciprocating IC Engine for A A Ship

27. The Interesting News
The world’s biggest engine is the Wärtsilä-Sulzer RTA96.
It’s the largest internal combustion engine ever built by man.
Wärtsilä-Sulzer RTA96-C is a 14-cylinder, turbocharged diesel engine that was specially designed to power the Emma Maersk which is owned by the Danish Maersk.
Wärtsilä-Sulzer RTA96, the world’s biggest engine, has a weight of 2.3 million kilogrammes.
If the weight of the average adult person is 70 kgs, this world’s biggest engine has a weight equivalent to the weight of 33,000 people.

28. Wärtsilä-Sulzer RTA96-C

29. Economies of Scale in Sea Transportation
Maersk Lines have done the world proud by providing cheap sea transportation that is costing cents instead of a dollar per every kg weight.
They are able to do this by using economies of scale in sea transportation.
It is getting cheaper to ship goods from USA to China and from China to USA.
It has now become cheaper to transport goods from China to a US port than to transport the same goods from a US port to the final destination inland of US by a truck.

30. Sankey Diagram for Spark Ignition Reciprocating IC Engine for A Car

31. Energy Losses in State of the Art Aircraft Engines