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![Page 1: jgl710-14](https://reader033.fdocuments.us/reader033/viewer/2022052902/557202734979599169a38925/html5/thumbnails/1.jpg)
Thermal Planning of A Power Plant Steam Generator
P M V SubbaraoAssociate Professor
Mechanical Engineering DepartmentI I T Delhi
Planning for Realization of Constant Pressure Heat Addition……
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Basic Geometry of A Furnace
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Thermal Planning of A SG
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•Heat loss from furnace surface.
•Combustion Losses
•Loss due to moisture in air.
•Loss due to moisture in fuel.
•Loss due to combustion generated moisture.
•Dry Exhaust Gas Losses
•~ 4 --- 5%
Heat gained by superheater & reheater
40%
Heat gained by economizer & air preheater
12%
Fuel Energy100%
Heat gained by boiling water40%
Hot gas
Flue gas
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Sequence of Energy Exchange from Flue Gas to Steam
PLATEN SH
FLUE GAS
ECONOMIZER
EVAPORATOR
COVECTIVE SH
RH PENDENT SH
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Burner
Flame
Hot Exhaust gases
Furnace Exit
Heat Radiation & Convection
Mechanism of Heat Exchange in Furnace
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Structure of Furnace Wall
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Boiler Furnace
• Structurally boiler furnace consists of the combustion space surrounded by water walls.
• The furnace volume is designed to perform:
• Release of the chemical energy of fuel by combustion
• The first task of combustion technology is
• to burn the fuel efficiently and steadily,
• to consume controlled excess air (as little as possible),
• To generate a flame with controlled shape which will generate lowest amount of pollutants.
• The furnace walls are designed to perform:
• Transfer of heat from the furnace to the working fluid inside the water walls.
• The important task of furnace heat removal is to produce a controlled Furnace Exit Gas Temperature (FEGT).
• FEGT is an important aspect of boiler safety.
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Thermal (Heat Transfer) Performance of A Furnace
• The flame transfers its heat energy to the water walls in the furnace by Radiation.
• Convective Heat Transfer < 5%.
• Only Radiation Heat Transfer is Considered!
• Complexities:
• Non uniform temperature of tubes.
• Variation of furnace gas temperature along its– Height
– Width
– Depth.
Non uniform Heat Flux !!!!!
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Cross-sectional distribution of Temperature
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