Sub – Super and Ultra Supercritical Boilers
BEST AVAILABLE TECHNOLOGY
The efficiency of thermoelectric power plants can be mainly increased by:
- raising live steam parameters (temperature and pressure);
- reducing the condenser pressure by means of a cold and effective cooling media – preferably sea water;
- using reheat or maybe double reheat;
- optimizing the feed water temperature;
- reducing the auxiliary power;
- increasing the boiler efficiency;
The boiler efficiency can be increased by:
- reducing the flue gas exit temperature by means of an effective air preheater;
- reducing Unburned Carbon (UBC) in the ash by an effective combustion;
- reducing the air excess and thereby obtaining a reduced flue gas heat loss;
- reducing the leakage in the air preheater;
- reducing the pressure loss of the water/steam cycle.
During the 1980’s and 90’s the technology has been developed from the subcritical through the supercritical to the ultra supercritical design with the first two units designed by BWE in commercial operation in 1997 and 1998 and the third unit in 2001.
The USC cycle is based on very high steam properties with pressure higher than 280 bar and temperature higher than 580°C.
Double reheating has been introduced in order to increase the efficiency and in order to reduce the wetness of the exhaust steam from the LP turbine.
The combustion system is designed to obtain the best possible conditions for low NOx combustion.
The combustion systems include Low NOx circular burners placed in the corners of the furnace.
Above each burner are placed OBA (Over Burner Air) openings, and at the top of the furnace OFA (Over Furnace Air) openings, which together with the air split in the burners establish the air staging.
- STF in consortium with BWE - Porto Tolle Power Station
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