This document discusses a cogeneration project opportunity using a micro-turbine system at the KMITL Combustion Lab. It provides an introduction to cogeneration systems, examples of applications that can generate both electricity and steam/hot water, and analyses of the energy and cost benefits compared to conventional boiler systems. The document also examines the impact of micro-turbine exhaust gas temperature on boiler performance and efficiency.

1. Cogeneration project
opportunity
KMITL COMBUSTION LAB

2. Introduction to cogeneration
KMITL COMBUSTION LAB
• conventional steam production in industrial
• What if we place Micro-turbine before the boiler ?
Air inlet
NGV inlet

3. Introduction to cogeneration
KMITL COMBUSTION LAB
• What if we place Micro turbine and afterburner before the boiler ?
• High value by product electrical generation
• Generating by product electrical power with the same cost of fuel heating value
• To generate by product electrical power while sustaining boiler capacity and
efficiency
Micro turbine
exhaust manifold
After burner
Exhaust stack
Air inletNGV inlet
Steam generation
Electrical
generation

4. Cogeneration introduction ( Micro turbine application )
KMITL COMBUSTION LAB
Duct combustor
Micro turbine & generator unit
Exhaust manifold duct
To boiler burner
Boiler unit

5. Cogeneration introduction ( piston engine application )
KMITL COMBUSTION LAB
• Considerable higher thermal efficiency ( around 40-45% )
• More complicate thermal recovery
• Exhaust direct combustion to boost temperature may not capable

6. Example of cogeneration application
KMITL COMBUSTION LAB
• Electrical & hot water generation ( commercial set )
• Electrical & steam generation with direct burner
• Electrical & cold water generation (trigeneration)
• Integration with ORC or Rankine bottom cycle ( >40% electrical efficiency )
Capstone with ORC integration

7. C65 electrical & hot water
generation commercial unit
KMITL COMBUSTION LAB

8. Capstone C65 energy analysis
KMITL COMBUSTION LAB
• Electrical & hot water generation, commercial package
246.67 KW
NGV burn C65
turbine
65 KW electrical generation
120 KW hot water generation
61.67 KW stack loss

9. Capstone C65 business analysis
KMITL COMBUSTION LAB
• Electrical & hot water generation, commercial package
398.31baht/hr
NGV burn C65
turbine
240.5 baht/hr electrical generation
193.77 baht/hr hot water generation
0 baht /hr
• profit = (240.5 + 193.77) – 398.31
= 35.96 baht / hr
= 315,009.6 baht / yr / unit
Note : NGV cost 17 baht/Kg , Electrical cost 3.7 baht / Kwh
NGV heating value @ 37.9 MJ/Kg

10. C65 Electrical & steam
generation with afterburner
KMITL COMBUSTION LAB

11. Energy analysis (compare with conventional boiler system )
KMITL COMBUSTION LAB
• Energy flow with conventional boiler
80 % boiler efficiency 85.4 KW stack loss
427 KW (fuel burn)
341.6 KW of steam generation

12. Business analysis (compare with conventional boiler system )
KMITL COMBUSTION LAB
341.6 KW of steam generation
• Money flow with conventional boiler
750 baht/hr (NGV burn)
80 % boiler efficiency 20 % stack loss
• pay 750 baht / hr for NGV fueled to generate steam 341.6 KW
Note : NGV cost 17 baht/Kg , Electrical cost 3.7 baht / Kwh
NGV heating value @ 37.9 MJ/Kg

13. Energy analysis ( C65 CHP application with afterburner )
KMITL COMBUSTION LAB
• Energy flow with CHP integrate system (micro turbine )
246.67 KW (fuel burn)
29 % GT efficiency 80 % boiler efficiency
341.6 KW of steam
generation
65 KW electrical generation
181.67 KW (exhaust gas)
246 KW (After burner)
427 KW (flue gas)
85.4 KW stack loss

14. Business analysis ( C65 CHP application with afterburner )
KMITL COMBUSTION LAB
• Money flow with CHP integrate system (micro turbine )
400 baht/hr (fuel burn)
29 % GT efficiency 80 % boiler efficiency
341.6 KW of steam
generation
240 baht/hr electrical generation
400 baht/hr (After burner)
427 KW (flue gas)
85.4 KW stack lossPay 800 baht to generate 341.6 Kw
Generate 240 baht of electrical power
Profit = 750 - (800 -240 )
= 190 baht / hr /unit
= 1,641,600 baht / yr /unit

15. Thermal process analysis on electrical and steam generation
with direct burner
KMITL COMBUSTION LAB
• Typical steam generation process
o Air / fuel was mixed and burned with burner
o Combustion hot gas temperature is nearly at adiabatic flame temperature
o Heat transfer characteristic in fire tube boiler is strongly depends on flame
temperature
• Heat transfer in fire tube boiler
o Radiation ( heat up tube surface of fire tube and hot gas )
o convection ( Transfer hot gas energy to water cooled tube surface )
o conduction ( Transfer energy from hot side tube surface to cool side )
• Hot gas temperature parameter is effect on heat transfer characteristic, boiler
capacity and boiler efficiency

16. Evaluation on boiler performance and efficiency on
combustion gas temperature and velocity (example)
KMITL COMBUSTION LAB
• Employ dimensionless approach
o Heat transfer through the tube wall electrical circuit analogy
o Fire tube boiler TA is known, temperature of the combustion gas
o Water temperature TB is know, temperature saturated water
o h1 is known by dimensionless approach correlation of …
o h2 can remodel to conduction analogy using K water approach or other
available correlation can be employed.
o Effect of radiation will resulting in raising of T1

17. Hot gas temperature analysis on electrical and steam
generation with direct burner
KMITL COMBUSTION LAB
• cogeneration application
Exhaust gas temperature was boosted by direct burner
• thermodynamics analysis (energy conservation )
The boosted exhaust gas temperature = (1-n)*(qin ) + (qad –qin ) / Cp air
Typical flue gas temperature = qad /Cp air
p
v

18. Thermal process analysis on electrical and steam generation
with direct burner
KMITL COMBUSTION LAB
• Micro-turbine with 30% thermal efficiency
• There is 15 % in temperature drop comparing to conventional burner ( for 2000K
adiabatic temperature fuel )
• How can we estimate boiler performance and capacity deteriorate due to this
effect ?

19. Business opportunity analysis (compare with conventional boiler system )
KMITL COMBUSTION LAB
80 Joule of steam generation
• Money flow with conventional boiler
100 baht (fuel burn)
80 % boiler efficiency 20 % stack loss
• Money flow with CHP integrate system (micro turbine )
xx baht (fuel burn)
xx baht electrical generation
29 % GT efficiency
xx baht (fuel burn)
80 % boiler efficiency
80 Joule of steam
generationxx joule (GT exhaust)

20. Heat transfer scaling law for systems prediction
KMITL COMBUSTION LAB
• Example NGV fueled Micro-turbine with 30% thermal efficienc

21. Future development opportunity
KMITL COMBUSTION LAB