cogeneration project opportunity

Cogeneration project opportunity

KMITL COMBUSTION LAB

Introduction to cogeneration


• conventional steam production in industrial

• What if we place Micro-turbine before the boiler ?

Air inlet

NGV inlet

Introduction to cogeneration


• 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

Cogeneration introduction ( Micro turbine application )


Duct combustor

Micro turbine & generator unit

Exhaust manifold duct To boiler burner

Boiler unit

Cogeneration introduction ( piston engine application )


• Considerable higher thermal efficiency ( around 40-45% ) • More complicate thermal recovery • Exhaust direct combustion to boost temperature may not capable

Example of cogeneration application


• 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

C65 electrical & hot water generation commercial unit


Capstone C65 energy analysis


• Electrical & hot water generation, commercial package

246.67 KWNGV burn C65

turbine

65 KW electrical generation

120 KW hot water generation

61.67 KW stack loss

Capstone C65 business analysis


• Electrical & hot water generation, commercial package

398.31baht/hrNGV 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

C65 Electrical & steam generation with afterburner


Energy analysis (compare with conventional boiler system )


• Energy flow with conventional boiler

80 % boiler efficiency 85.4 KW stack loss

427 KW (fuel burn)

341.6 KW of steam generation

Business analysis (compare with conventional boiler system )



• 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

Energy analysis ( C65 CHP application with afterburner )


• Energy flow with CHP integrate system (micro turbine )

246.67 KW (fuel burn)

29 % GT efficiency 80 % boiler efficiency


65 KW electrical generation

181.67 KW (exhaust gas)

246 KW (After burner)

427 KW (flue gas)

85.4 KW stack loss

Business analysis ( C65 CHP application with afterburner )


• Money flow with CHP integrate system (micro turbine )

400 baht/hr (fuel burn)

29 % GT efficiency 80 % boiler efficiency


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 powerProfit = 750 - (800 -240 ) = 190 baht / hr /unit = 1,641,600 baht / yr /unit

Thermal process analysis on electrical and steam generation with direct burner


• Typical steam generation process o Air / fuel was mixed and burned with burnero Combustion hot gas temperature is nearly at adiabatic flame temperatureo 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

Evaluation on boiler performance and efficiency on combustion gas temperature and velocity (example)


• 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

Hot gas temperature analysis on electrical and steam generation with direct burner


• 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

Thermal process analysis on electrical and steam generation with direct burner


• 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

?

Business opportunity analysis (compare with conventional boiler system )


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 generation xx joule (GT exhaust)

Heat transfer scaling law for systems prediction


• Example NGV fueled Micro-turbine with 30% thermal efficienc

Future development opportunity


cogeneration project opportunity

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