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Auxiliary Steam System Presentation Transcript
1.Auxiliary Steam System
2.Presentation outline
Sources of Aux steam supply
PRDS Station
Uses of Aux steam
Flange and stud heating
Rotor heating
Sources of Aux steam supply
PRDS Station
Uses of Aux steam
Flange and stud heating
Rotor heating
3.SOURCES
Auxiliary boiler.
Station PRDS header (from other running units)
Under unit running condition Steam for turbine auxiliary steam header is normally taken from extraction lines depending on load on the turbine sources may be:
Main steam line through pr and temp reducing valves
CRH line
Auxiliary boiler.
Station PRDS header (from other running units)
Under unit running condition Steam for turbine auxiliary steam header is normally taken from extraction lines depending on load on the turbine sources may be:
Main steam line through pr and temp reducing valves
CRH line
4.PRDS Station
It Consists of
Set of pressure reducing cum control valves
Set of temp reducing (spray) valves
For maintaining desired pressure and temp.
It Consists of
Set of pressure reducing cum control valves
Set of temp reducing (spray) valves
For maintaining desired pressure and temp.
5.For a 210 MW Thermal Power Unit using coal as basic fuel, auxiliary steam is one of the important systems. The current practice is to have two different headers:-
Turbine Auxiliary Steam Header
Boiler Auxiliary Header
Turbine Auxiliary Steam Header
Boiler Auxiliary Header
6.Uses of Auxiliary Steam on Turbine side
To turbine gland seal header.
To ejector system of condenser (main as well as starting ejector).
to Deaerator as pegging steam
For flange & stud heating.
Interconnection to station PRDS header for supplying aux steam to other units.
To turbine gland seal header.
To ejector system of condenser (main as well as starting ejector).
to Deaerator as pegging steam
For flange & stud heating.
Interconnection to station PRDS header for supplying aux steam to other units.
7.Burner atomisation,cleaning, scavenging
SCAPH charging during cold start up
Regenerative air heater sooth blowing.
Off Sites:
HFO station: Fuel oil system heating fuel, oil storage tanks, pipelines, fuel oil heaters.
SCAPH charging during cold start up
Regenerative air heater sooth blowing.
Off Sites:
HFO station: Fuel oil system heating fuel, oil storage tanks, pipelines, fuel oil heaters.
8.AUX STEAM HEADER
9.Flange, Stud & Rotor Heating System
10.Flange and Stud heating
Used for quick starting of turbine from warm or cold start.
Helps in reducing the temperature difference of the metal to reduce thermal stress.
The device consists of jackets welded to side walls of casing flanges and special piping complete with fittings and measuring instruments for steam inlet, outlet, and drains.
The flanges and studs are heated with live steam bled from pipelines before main stop valve (ESV).
Used for quick starting of turbine from warm or cold start.
Helps in reducing the temperature difference of the metal to reduce thermal stress.
The device consists of jackets welded to side walls of casing flanges and special piping complete with fittings and measuring instruments for steam inlet, outlet, and drains.
The flanges and studs are heated with live steam bled from pipelines before main stop valve (ESV).
11.The headers, supplying steam to the flanges and studs, are provided with safety valves and pressure gauges for regulating pressure in the headers.
To check the temperature difference of the metal across the width of casing and between flanges and studs of the casing, thermocouples have been provided.
Careful check of the metal temp. is required during heating process.
To check the temperature difference of the metal across the width of casing and between flanges and studs of the casing, thermocouples have been provided.
Careful check of the metal temp. is required during heating process.
12.The temperature difference across the width of the casing flange should be within 50°C. The temperature of outside flange surface should never exceed that measured with a thermocouple at a maximum depth inside the flange.
The difference between the flange and stud temperature should not exceed 20°C and the stud temperature should never be more than that of the flange.
When starting the turbine from cold or hot (temperature of metal of the upper half of the HP- casing being up to 250°C, heating of flanges and studs is permitted provided differential expansion of the rotor is positive and not less than 1 mm.
The difference between the flange and stud temperature should not exceed 20°C and the stud temperature should never be more than that of the flange.
When starting the turbine from cold or hot (temperature of metal of the upper half of the HP- casing being up to 250°C, heating of flanges and studs is permitted provided differential expansion of the rotor is positive and not less than 1 mm.
13.It is not permitted to operate the flange heating device:
If the differential expansion of rotor is less than 1 mm.
If the differential expansion indicating and recording instruments are either out of order or disconnected.
In order to maintain proper tightening of flange joints, it is necessary to first supply steam for heating flanges and only then after some time to studs.
If the differential expansion of rotor is less than 1 mm.
If the differential expansion indicating and recording instruments are either out of order or disconnected.
In order to maintain proper tightening of flange joints, it is necessary to first supply steam for heating flanges and only then after some time to studs.
14.Rotor Heating
In case the contraction of HP rotor reaches 0.8 mm and that of IP rotor 1.5 mm. fresh steam is supplied to the front sealing of HP & IP turbines. In order to control the contractions of HP & IP rotor the steam is supplied at a higher temperature then that of the turbine casing at the front sealing till it comes under control.
In case the contraction of HP rotor reaches 0.8 mm and that of IP rotor 1.5 mm. fresh steam is supplied to the front sealing of HP & IP turbines. In order to control the contractions of HP & IP rotor the steam is supplied at a higher temperature then that of the turbine casing at the front sealing till it comes under control.
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