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SLIDING PRESSURE OPERATION Presentation Transcript
1.SLIDING PRESSURE OPERATION
2.Critical Parameters
MW
MS Pressure
external parameter is frequency of the network
MW
MS Pressure
external parameter is frequency of the network
3.Response Time
Response of the Turbine is fast
Response of the Boiler is slow due to transport lag and Thermal inertia.
Turbine will be able to maintain only one unit parameter MW or main steam pressure. The other is to be controlled, naturally by the boiler.
Response of the Turbine is fast
Response of the Boiler is slow due to transport lag and Thermal inertia.
Turbine will be able to maintain only one unit parameter MW or main steam pressure. The other is to be controlled, naturally by the boiler.
4.Modes of Operation
turbine follow mode
boiler follow mode.
turbine follow mode
boiler follow mode.
5.Turbine follow mode
Turbine maintains throttle steam pressure. The MW depends on the steam output from the Boiler. The variations in the Boiler steam output will be resulting variations in MW output.
Turbine follow mode gives more stability to unit by controlling main steam pressure perfectly and fastly which is a very important unit parameter.
Turbine maintains throttle steam pressure. The MW depends on the steam output from the Boiler. The variations in the Boiler steam output will be resulting variations in MW output.
Turbine follow mode gives more stability to unit by controlling main steam pressure perfectly and fastly which is a very important unit parameter.
6.Turbine maintains MW demands and Boiler maintains main steam pressure. Turbine will be responding to grid requirement fastly because of droop characteristic set in EHC and Boiler will be following to maintain main steam pressure if combustion controls are in Auto.
7.coordinated mode of operation
unit/master control station sets MW set point
Turbine will be controlling the MW
Boiler will be trying to control main steam pressure
unit/master control station sets MW set point
Turbine will be controlling the MW
Boiler will be trying to control main steam pressure
8.Sliding Pressure Operation
MS Pressures varies according to generator output.
turbine governing valves kept wide open.
Utilizing sliding pressure, the thermal efficiency of the steam turbine is improved at partial operating loads through decreasing thermodynamic efficiency as follows, by comparison with constant pressure type operation:
(1) A smaller governing value loss enables improvement of high pressure turbine internal efficiency
(2) Decrease of feed water pump throughput
(3) Boiler reheat steam temperature can be maintained at higher levels because of higher temperatures in high-pressure turbine exhaust steam.
MS Pressures varies according to generator output.
turbine governing valves kept wide open.
Utilizing sliding pressure, the thermal efficiency of the steam turbine is improved at partial operating loads through decreasing thermodynamic efficiency as follows, by comparison with constant pressure type operation:
(1) A smaller governing value loss enables improvement of high pressure turbine internal efficiency
(2) Decrease of feed water pump throughput
(3) Boiler reheat steam temperature can be maintained at higher levels because of higher temperatures in high-pressure turbine exhaust steam.
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