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TURBINE FLEET IN NTPC Presentation Transcript
1.TURBINE FLEET IN NTPCSteam Turbines of Following OEM,s are running in NTPC
LMZ ( Russia)
KWU, Siemens ( Germany)
ABB-Alstom (Germany)
GEC- Alstom ( U.K)
SKODA, (Chezkoslovakia)
MHI ( Japan)
GE (USA)
ANSALDO ( Italy)
2.WORKING OF STEAMTURBINE
A steam turbine works on the principle of conversion of High pressure & temperature steam into high Kinetic energy , thereby giving torque to a moving rotor.
For above energy conversion there is requirement of converging /Converging-Diverging Sections
Such above requirement is built up in the space between two consecutive blades of fixed and moving blades rows.
LMZ ( Russia)
KWU, Siemens ( Germany)
ABB-Alstom (Germany)
GEC- Alstom ( U.K)
SKODA, (Chezkoslovakia)
MHI ( Japan)
GE (USA)
ANSALDO ( Italy)
2.WORKING OF STEAMTURBINE
A steam turbine works on the principle of conversion of High pressure & temperature steam into high Kinetic energy , thereby giving torque to a moving rotor.
For above energy conversion there is requirement of converging /Converging-Diverging Sections
Such above requirement is built up in the space between two consecutive blades of fixed and moving blades rows.
3.TYPE OF TURBINE
IMPULSE TURBINE = In a stage of Impulse turbine the pressure/Enthalpy drop takes place only in Fixed blades and not in the moving blades
REACTION TURBINE = In a stage of Reaction Turbine the Pressure/enthalpy drop takes place in both the fixed and moving blades.
IMPULSE TURBINE = In a stage of Impulse turbine the pressure/Enthalpy drop takes place only in Fixed blades and not in the moving blades
REACTION TURBINE = In a stage of Reaction Turbine the Pressure/enthalpy drop takes place in both the fixed and moving blades.
4.DEGREE OF REACTION
5.Velocity Compounded Turbines Here the High temperature, Pressure Steam is expanded in a single row of fixed blades into very high velocity which is then fed to 2 or 3 rows of moving blades with one each guide/turning row placed in between the two moving stages.
Pressure compounding Turbines Here the pressure is dropped in stages and employs low velocity of Steam in each stage. Each stage consists of Fixed blade( nozzles) and moving blades .
Pressure compounding Turbines Here the pressure is dropped in stages and employs low velocity of Steam in each stage. Each stage consists of Fixed blade( nozzles) and moving blades .
6.All the Steam turbines in NTPC are PRESSURE COMPOUNDED ,Except the 110 MW Skoda make steam Turbine at Tanda ,Muzaffarpur and Talcher ,where two stage Velocity compounding impulse rows are there at the inlet of HP Turbine.
The LMZ Turbines of 210 MW has one pure impulse in the first stage which is also the controlling stage.
The LMZ Turbines of 210 MW has one pure impulse in the first stage which is also the controlling stage.
7.LMZ Turbines are more impulse in nature
KWU Turbines are more reactive in nature
Sparing Rateau and Curtis stages, all other stages of turbine is a mixture of Impulse and Reaction with varying degree of reaction.
Pressure/Enthalpy drop is more in Impulse stage than in reaction.
Comparatively Reaction Blade is more efficient than the Impulse blade.
Impulse turbine requires fewer no. of stages than reaction turbine for same condition of steam and power requirement.
KWU Turbines are more reactive in nature
Sparing Rateau and Curtis stages, all other stages of turbine is a mixture of Impulse and Reaction with varying degree of reaction.
Pressure/Enthalpy drop is more in Impulse stage than in reaction.
Comparatively Reaction Blade is more efficient than the Impulse blade.
Impulse turbine requires fewer no. of stages than reaction turbine for same condition of steam and power requirement.
8.TYPE OF BEARINGS
Cylindrical Bearing( Single wedge ring) This has single oil inlet
Elliptical Bearing( Double wedge bearing)
This has double oil inlet
Segment Bearing( Multi wedge Bearing)
Cylindrical Bearing( Single wedge ring) This has single oil inlet
Elliptical Bearing( Double wedge bearing)
This has double oil inlet
Segment Bearing( Multi wedge Bearing)
9.Cylindrical bearings are normally used for system where no transients are envisaged particularly in turbines without controlling stage, whereby one side radial impulse due to steam forces is not there.
Multi wedge bearings are used by installing bearings in segments . Each Segment will have its own wedge.
Multi wedge bearings can take more load ,can dampen the sudden disturbance on shaft and there is no formation of Oil Whirl and low frequency vibration components.
Multi wedge bearings are used by installing bearings in segments . Each Segment will have its own wedge.
Multi wedge bearings can take more load ,can dampen the sudden disturbance on shaft and there is no formation of Oil Whirl and low frequency vibration components.
10.BEARING FLOAT
Value more than the design value can lead to accelerated wearing of the Babbit pads
Value more than the design value can lead to accelerated wearing of the Babbit pads
11.ANCHOR POINT
Anything when heated will expand. Same is true for Turbine rotors and Casings.
Problem with rotors is more complex as it is also subjected to the axial thrust also.
To allow their controlled motion during operation and to prevent any eventuality between rotor and casing they are required to be anchored
Rotors are anchored at Bearing no 2(between HP &IP) by means of thrust bearing. In some Turbines they are also anchored at free end
Thrust bearing( Anchor point) is always located near High temperature end to minimize the differential expansion.
Anything when heated will expand. Same is true for Turbine rotors and Casings.
Problem with rotors is more complex as it is also subjected to the axial thrust also.
To allow their controlled motion during operation and to prevent any eventuality between rotor and casing they are required to be anchored
Rotors are anchored at Bearing no 2(between HP &IP) by means of thrust bearing. In some Turbines they are also anchored at free end
Thrust bearing( Anchor point) is always located near High temperature end to minimize the differential expansion.
12.ANCHOR POINTS
Casings which are connected together by means of pedestals and keys have LPT front as the anchor point.
It is to be noted that rotor rests on the bearings and bearings further rests on the pedestals
The pedestals can be moving / sliding or can be fixed. When it is sliding it carries bearing along with it which further carries rotor along with it.
When pedestals are fixed the necessary casing expansion is taken by the bellows at the ends.
Total Expansion of Turbine can be calculated which is appx. Equal to La?T where
L = Length of Turbine
a = coefficient of thermal expansion
T= Difference of temperature.
Casings which are connected together by means of pedestals and keys have LPT front as the anchor point.
It is to be noted that rotor rests on the bearings and bearings further rests on the pedestals
The pedestals can be moving / sliding or can be fixed. When it is sliding it carries bearing along with it which further carries rotor along with it.
When pedestals are fixed the necessary casing expansion is taken by the bellows at the ends.
Total Expansion of Turbine can be calculated which is appx. Equal to La?T where
L = Length of Turbine
a = coefficient of thermal expansion
T= Difference of temperature.
13.DIFFERENTIAL EXPANSION
It is the difference between the rotor expansion and the Casing Expansion
It is +ve if rotor expands more than casing
It is -ve if casing expands more than rotor
During initial startup diff Exp. is +ve as rotor mass is less and expands at more faster stage than casing. After full load this gap reduces.
Diff. Expansion pick up is mounted at the farthest point from the anchor point to record the max difference.
It is the difference between the rotor expansion and the Casing Expansion
It is +ve if rotor expands more than casing
It is -ve if casing expands more than rotor
During initial startup diff Exp. is +ve as rotor mass is less and expands at more faster stage than casing. After full load this gap reduces.
Diff. Expansion pick up is mounted at the farthest point from the anchor point to record the max difference.
14.AXIAL SHIFT
Axial shift on the Rotors comes due to two components
Direct Pressure Thrust: It is the axial thrust due the diff of the pressure X Area component across the moving stage blading and Discs
Velocity Component: It is due to diff. of the velocity X Mass component across the moving stage blading.
Total summation of all the above components leads to the Axial Thrust.
Axial shift on the Rotors comes due to two components
Direct Pressure Thrust: It is the axial thrust due the diff of the pressure X Area component across the moving stage blading and Discs
Velocity Component: It is due to diff. of the velocity X Mass component across the moving stage blading.
Total summation of all the above components leads to the Axial Thrust.
15.Axial Thrust is +ve if it is towards generator
Axial Thrust is -ve if it is towards HPT front
There are many ways of balancing axial thrust
1. Double flow self balanced cylinder
2. Mutually balanced individual cylinders
3. By putting balancing drum in the HP Module
4. Having holes in the Discs of the blading
5. Reverse flow in individual cylinder after partial Expansion.
6. Optimizing Steam Extraction Locations
Axial Thrust is -ve if it is towards HPT front
There are many ways of balancing axial thrust
1. Double flow self balanced cylinder
2. Mutually balanced individual cylinders
3. By putting balancing drum in the HP Module
4. Having holes in the Discs of the blading
5. Reverse flow in individual cylinder after partial Expansion.
6. Optimizing Steam Extraction Locations
16. 7. Sealing fins are also important component of balancing axial thrust
The Residual thrust is taken care by the Thrust pads.
Tripping Limits of Axial shift
The Max. + ve axial shift tripping value is just less than the minimum axial gap in the HP Casing which is in its first stage.
The Max. - ve axial shift tripping value is just less than the minimum axial gap in the IP Casing which is in its first stage.
17.GOVERNING SYSTEM
To regulate the speed of the Turbine at various loads in a isolating set
To regulate the load as per the frequency demand when working in a grid network.
To prevent and protect the turbine from over speeding.
To allow on line testing of various safety protections .
To enable the tripping of TG set in the event of actuation of protections.
Safe and healthy loading of the TG Set
The Residual thrust is taken care by the Thrust pads.
Tripping Limits of Axial shift
The Max. + ve axial shift tripping value is just less than the minimum axial gap in the HP Casing which is in its first stage.
The Max. - ve axial shift tripping value is just less than the minimum axial gap in the IP Casing which is in its first stage.
17.GOVERNING SYSTEM
To regulate the speed of the Turbine at various loads in a isolating set
To regulate the load as per the frequency demand when working in a grid network.
To prevent and protect the turbine from over speeding.
To allow on line testing of various safety protections .
To enable the tripping of TG set in the event of actuation of protections.
Safe and healthy loading of the TG Set
18.TYPES OF GOVERNING-I
Nozzle Governing
Throttle governing
Bypass Governing
Governing is effected by varying the amount of steam which is further done by changing the positions of control valves.
Any Throttling of Steam will lead to losses . In governing system along with the change of quantity of steam the quality of the steam also changes. Therefore Throttling should be minimum.
Nozzle Governing
Throttle governing
Bypass Governing
Governing is effected by varying the amount of steam which is further done by changing the positions of control valves.
Any Throttling of Steam will lead to losses . In governing system along with the change of quantity of steam the quality of the steam also changes. Therefore Throttling should be minimum.
19.BYPASS GOVERNING
It is employed in small capacity turbines running on high pressure conditions and with small blading dimensions.
Here the loading up to appx 80% ( Economic loading ) is met by normal control valves feeding the First stage. For higher loading , to supply more steam which is not possible due to small blading dimensions ( can lead to operational problems) the extra quantity of the steam is fed to the intermediate section of turbine bypassing the initial high pressure stages.
20.TYPES OF GOVERNING-II
Constant Pressure Mode: Here pressure upstream of control valves is kept constant and change is made by changing the position of control valves.
Variable Pressure mode:Here control valves are in full open position and pressure upstream of control valves varies proportionately with the load requirement.
Response of Constant pressure Mode is much faster than Variable pressure mode, but Constant pressure leads to more losses.
It is employed in small capacity turbines running on high pressure conditions and with small blading dimensions.
Here the loading up to appx 80% ( Economic loading ) is met by normal control valves feeding the First stage. For higher loading , to supply more steam which is not possible due to small blading dimensions ( can lead to operational problems) the extra quantity of the steam is fed to the intermediate section of turbine bypassing the initial high pressure stages.
20.TYPES OF GOVERNING-II
Constant Pressure Mode: Here pressure upstream of control valves is kept constant and change is made by changing the position of control valves.
Variable Pressure mode:Here control valves are in full open position and pressure upstream of control valves varies proportionately with the load requirement.
Response of Constant pressure Mode is much faster than Variable pressure mode, but Constant pressure leads to more losses.
21.Mechanical: Transducer is mechanical centrifugal speed governor which actuates controls valves through mechanical linkages.
Hydro mechanical: Here transducer is a centrifugal speed governor .It is connected to a Hydraulic system where the signal is amplified so that Control valves servomotor can be actuated.
Hydraulic: Here speed transducer is a centrifugal pump whose discharge pressure is proportional to square of speed. This signal is sent to hydraulic converter which generates
Hydro mechanical: Here transducer is a centrifugal speed governor .It is connected to a Hydraulic system where the signal is amplified so that Control valves servomotor can be actuated.
Hydraulic: Here speed transducer is a centrifugal pump whose discharge pressure is proportional to square of speed. This signal is sent to hydraulic converter which generates
22. a signal which is proportional to valve opening/Closure is required. Before applying it to control valves servomotor this signal is suitably modified.
Electro Hydraulic:Here transducer can be electrical or Electronic. The generated signal after processed electronically and electrically is fed to a Electro- hydraulic converter which converts electrical signal into Hydraulic signal.Hydraulic signal before applying to control valve servomotor is suitably amplified.
Electro Hydraulic:Here transducer can be electrical or Electronic. The generated signal after processed electronically and electrically is fed to a Electro- hydraulic converter which converts electrical signal into Hydraulic signal.Hydraulic signal before applying to control valve servomotor is suitably amplified.
23.REGULATION
Turbine having less regulation will be more sensitive in the grid and hence will share more load and vice versa
Normally base load plant has high regulation and Peak load plant has small regulation.
Turbine having less regulation will be more sensitive in the grid and hence will share more load and vice versa
Normally base load plant has high regulation and Peak load plant has small regulation.
24.VIBRATION
Its manifestation in the form of amplitude of Oscillation, indicate some problem with the equipment e.g. Fever in a body
The impact of high vibration usually are loss of integrity of components and associated generation loss because of forced outage either as a preventive measure or consequence of any failure due to high vibration/vice versa.
Its manifestation in the form of amplitude of Oscillation, indicate some problem with the equipment e.g. Fever in a body
The impact of high vibration usually are loss of integrity of components and associated generation loss because of forced outage either as a preventive measure or consequence of any failure due to high vibration/vice versa.
25. CAUSES, TYPE OF PROBLEMS
AND CORRECTIVE ACTIONS
AND CORRECTIVE ACTIONS
26.INFORMATION REQUIRED TO DIAGNOSE THE PROBLEM
Frequency components causing change in amplitude of vibration (low frequency,1x, higher frequency etc.)
Vector position (Phase and Amplitude) of 1x across different bearings in H,V and A directions, at different speeds.
Bode plots,Cascade,Waterfall,Orbit plots,time waveform
Process parameters correlation with load,speed,vacuum, etc.
Frequency components causing change in amplitude of vibration (low frequency,1x, higher frequency etc.)
Vector position (Phase and Amplitude) of 1x across different bearings in H,V and A directions, at different speeds.
Bode plots,Cascade,Waterfall,Orbit plots,time waveform
Process parameters correlation with load,speed,vacuum, etc.
27.LATEST DEVELOPMENTS-ONLINE DIAGNOSTIC SYSTEMS
28.FEATURES
Bar Graph
Time waveform,Orbit
Trend, Multi variable trend, XY plots
Frequency spectrum,
Acceptance region
Bode,Water fall, Cascade
Shaft average Centreline plot
Bar Graph
Time waveform,Orbit
Trend, Multi variable trend, XY plots
Frequency spectrum,
Acceptance region
Bode,Water fall, Cascade
Shaft average Centreline plot
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