Transcript
SELECTION OF SITE FOR STEAM POWER PLANT
Availability of land
Availability of sufficient amount of good boiler feed water and cooling water
Availability of fuel.
Necessity for future expansion.
Availability of other power other power services
Away from urban areas
Initial cost of plant
Magnitude and nature of load to be handled
GENRAL LAYOUT
Fuel handling unit
Ash handling unit
Boiler unit
Feed water unit
Cooling water unit
Generator unit
Turbine unit
MAIN FLOW CIRCUITS
Fuel and ash circuit
Air and gas circuit
Feed water and steam circuit
Cooling water circuit
FUEL AND ASH CIRCUIT
Fuel stored is fed to boiler through
conveyer belt.
Coal – particular size for complete
burning.
Coal is passed through crushers , sizers
and magnetic separators before feeding
to boiler.
As a result of combustion, ash is
produced from coal fuel which is
removed from boiler through ash
handling equipments.
AIR AND GAS CIRCUIT
Air is required for complete combustion of the fuel – supplied through Forced draught(FD) and Induced draught(ID) fans.
Air which is fed to the boiler, is passed through preheater – to extract energy of flue gases from boiler.
Flue gas consist of several gases and ash – passed through precipitator and finally go to atmosphere via chimney .
FEED WATER AND STEAM CIRCUIT Most power plants are condensing type – steam is
converted to water by condenser.
For safety of turbine water is demineralized – better economic operation
Adding make up water in feed water system compensate leakages.
The boiler feed pump (BFP) feeds water to boiler drum – heated to form steam.
Wet steam heated in super heater passed to turbine and runs it
FEED WATER AND STEAM CIRCUIT
Stages of prime mover depending on size of power plant
1. High Pressure Turbine HP
2. Intermediate Pressure Turbine IP
3. Low Pressure turbine LP
COOLING WATER CIRCUIT
To condensate the steam in condenser and maintaining low pressure in it, large quantity of cooling water is required.
After passing it through condenser, it is fed back to river or pondage.
Cooling tower or cooling ponds are used in case of shortage.
Drawback- Excessive water loss
PARTS OF STEAM POWER PLANT
Boiler- Water tube boilerCoal Mills Boiler feed pump- high
capacity IMAir preheater- extract heat
from flue gasesDraught system- supply air to
the furnace and to take the flue gases from the boiler
Economizers- extract heat from flue gases
PARTS OF STEAM POWER PLANT
Superheaters and ReheatersTurbinesCondenserCooling towerAlternators- high speed
synchronous generators
COOLING OF ALTERNATOR
Important due to damage of insulation at high temperature.
Closed circuit cooling widely used in modern alternators (Hydrogen as cooling medium).
ADVANTAGES OF HYDROGEN COOLING More heat transfer and thermal
conductivity is 7 times more than air. Low ventilation losses Life of insulation is more as no
oxidation of insulating material . Fire hazards minimized Less noise Size of frame reduced
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