1. GAS TURBINES
Presented by . . . Prem Baboo

2. GAS TURBINES AT N.F.L.
VIJAIPUR
GTG-1 & 2: PG-5361 P
RATING at 45OC on NG & Naphtha
Base / Peak Load: 17225 / 19237 KW
&
16990 / 18980 KW
GTG-3 : PG-5371 PA
RATING at 35OC on NG & Naphtha:
Base / Peak Load: 19970 / 21910 KW
&
19740 / 20950 KW
GT(PAC) : M-5261 RA

3. HEAY DUTY GAS TURBINES
MS5000 SINGLE and TWO shaft configurations
for both Generator drive and Mechanical drive.
MS5001 and MS6001 are Gear-Box driven
units that can be applied in 50 Hz and 60 Hz.
Beyond Frame 6 all are direct drive units.
MS7000 series for 60 Hz >>>3600 RPM.
MS9000 series for 50 Hz >>>3000 RPM.

4. H
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5. Generator Applications
35,800 ~ 345,600 HP (26,000 ~ 255,600 kW)

6. Mechanical Drives
14,520 ~108,990 HP (10,828 ~ 80,685 kW)

7. BRAYTON CYCLE
P
R
E
S
S
U
R
E
VOLUME
SUCK
SQUEEZE
BURN
BLOW

8. BRAYTON CYCLE
P
R
E
S
S
U
R
E
VOLUME
COMPRESSOR
COMBUSTOR
TURBINE

9. Basic Components

10. Basic Components

11. Compressor
Draws in air & compresses it
Combustion Chamber
Fuel pumped in and ignited to burn with compressed air
Turbine
Hot gases converted to work
Can drive compressor & external load

12. Compressor
Draws in air & compresses it
Combustion Chamber
Fuel pumped in and ignited to burn with compressed air
Turbine
Hot gases converted to work
Can drive compressor & external load

13. Compressor
Draws in air & compresses it
Combustion Chamber
Fuel pumped in and ignited to burn with compressed air
Turbine
Hot gases converted to work
Drive compressor & external load

14. Theoretical and Actual Brayton Cycle

15. SIMPLE CYCLE

16. COGENERATION CYCLE

17. COMBINED CYCLE

18. Factors Affecting Gas Turbine Performance
Since the gas turbine is an air-breathing engine, its
performance is changed by anything that affects
the density and / or mass flow of the
air intake to the compressor
Ambient Air Temperature
Site Elevation / Atmospheric Pressure
Humidity
Inlet and Exhaust Losses
Fuels
Turbine Cooling ( . . . air extraction )

19. EFFECT OF AMBIENT TEMPERATURE
CURVES ARE DIFFERENT FOR DIFFERENT
MODELS AND CYCLE

20. EFFECT OF ATMOSPHERIC PRESSURE
AIR FLOW & OUTPUT DECREASES
::::::: AS SITE ELEVATION INCREASES

21. EFFECT OF HUMIDITY

22. EFFECT OF
INLET & EXHAUST LOSSES

23. METHOD OF IMPROVING
OUTPUT

24. METHOD OF IMPROVING
OUTPUT

25. METHOD OF IMPROVING
OUTPUT

26. METHOD OF IMPROVING
OUTPUT

27. METHOD OF IMPROVING
OUTPUT

28. METHOD TO IMPROVE THE EFFICIENCY

29. GAS TURBINE MANILY CAN BE DIVIDED
IN TO 4 SUB-SECTION
ACCSSORY COMPARTMENT
MAIN GAS TURBINE
LOAD GEAR COMPARTMANT
GENERATOR AND EXCITER

30. MAJOR COMPONENTS OF
GAS TURBINE
INLET SYSTEM
COMPRESSOR
COMBUSTION SYSTEM
TURBINE
EXHAUST
BEARINGS

31. INLET SECTION
Consists of inlet plenum
which inducts air into the
compressor inlet casing

32. COMPRESSOR SECTION
COMPRESSOR SECTION CONSISTS OF
Inlet Casing
Forward Casing
Aft Casing
Discharge Casing
Blading
Compressor Rotor

33. INLET CASING
The inlet section directs
the flow of outside air
from the air inlet
equipment into the
compressor blading.
Contains the inlet guide
vane assembly.
The No #1 Bearing
assembly and the low
pressure air seals.

34. INLET GUIDE VANE
IGV permits fast, smooth
acceleration of the turbine
without compressor surge.
A hydraulic cylinder
mounted on a base cross
member actuates the IGV
through a large ring gear and
multiple small pinion gears.

35. FORWARD CASING
It contains stator
blading for stages
0 through 3.
Bleed air from the
fourth rotor stage can
be extracted through
four ports which are
located about the aft
section of the
compressor casing.

36. AFT CASING
It contains the stator blading for stages 4 through 9.
Bleed air from 10th rotor stage (between 9th and 10th
stator stages) can be extracted through four ports.

37. DISCHARGE CASING
It contains stator
blading for stages
10 through 16 and
Exit guide vane
stages 1 and 2.
Provides the mounting
surface for the
combustion chambers.
Supports the inner
case assembly.

38. Axial Flow Compressor

40. SEQUENTIAL ASSEMBLY

41. ASSEMBLEDROTOROFATYPICALGASTURBINE
TURBINE BLADES
COMPRESSOR BLADES
THRUST COLLAR

42. Fuel Nozzles
Combustion
Components
Rotor
Nozzles
Buckets
TURBINE SECTION

43. COMBUSTION SECTION
THE COMBUSTION SYSTEM CONSISTS OF
Ten Combustion Chambers.
Fuel Nozzles.
Cross fired tubes.
Transition pieces.
Combustion Liners.
Spark plugs and Flame detectors.

44. GAS TURBINE COMBUSTION SYSTEM

45. COMBUSTION AIR
COOLING AIR
DILUTING AIR

46. FUEL NOZZLE
Dual fuel
Gas and HSD
Liquid fuel atomization is
with air
Purge air provision for
liquid path

47. CROSS FIRE TUBES
Carries flame from
Chambers No #1 & # 2
to all other chambers
during start up and to
unfired Combustion
Chambers

48. COMBUSTION LINERS
Combustion
Liner

49. Spring
Seal
Body
Cross fire
tube collar
Cooling Holes
SUBLEVEL COMPONENTS
Cap Assembly
Fuel Nozzle
Collar
Liner Stopper

50. Fuel Nozzles
Combustion
Components
Rotor
Nozzles
Buckets
OVER VIEW OF GAS TURBINE
TP Location

51. FWD
Frame
FWD
Mount
TP body
AFT
Mount
Float seals
Sub Level Components . . .

52. TURBINE SECTION
II nd STAGE
NOZZLE
I st STAGE
BUCKETS
I st STAGE
NOZZLE
TRANSTION PIECE

53. Power nozzles provide the mechanism of converting energy of
burned gases into kinetic energy that drives the turbine.
The power nozzles are located at turbine Section of the unit.
Hot combustion gases hit the nozzle to
accelerate and change direction.
NOZZLE

54. GAS TURBINE NOZZLE
FIRST STAGE NOZZLE SECOND STAGE
NOZZLE

55. Support ring
Stg 1 Bucket
Stg 2 Diaphragm
Stg 2 Nozzle
Stg 2 Bucket
Stg 1 Shroud
Stg 2 Shroud

56. FIRST STAGE
BUCKET

57. SECOND
STAGE
BUCKET

58. EXHAUST CASING
 Exhaust casing directs exhaust
gases to Exhaust Duct
 Contains Bearing No # 2
assembly
 Acts as a Diffuser to push
exhaust gases into
Exhaust Duct

59. BEARINGS
Gas turbine is supported on two nos elliptical
journal bearings
Bearing 1 at compressor inlet casing
Bearing 2 at exhaust casing end
Bearing 1 also consists of active and non active
thrust bearings

60. BEARINGS

61. ACCESSROY COMPARTMENT
 STARTING DEVICE ( DIESEL ENGINE)
 TORQUE CONVERTER
 HYDRAULIC RATCHET MECHANISUM
 JAW CLUTCH
 AUXILLARY LUBE OIL AND EM LUBE OIL PUMP
 AUXILLARY HYDRAULIC OIL PUMP
 LUBE OIL TANK
 FLOW DIVIDER
 HIGH PRESSURE LIQUID FUEL FILTER
 ACCESSORY GEAR BOX

62. ACCESSORY GEAR BOX
 PROVIDES DRIVE TO MOST OF THE SUPPORTS SYSTEM
REQUIRED FOR CONTROL AND PROPER FUNCTIONOING OF GAS
TURBINE LIKE
 MAIN LUBE OIL PUMP
 MAIN HYDRAULIC OIL PUMP
 ATOMISING AIR COMPRESSOR
 LIQUID FUEL FORWARDING PUMP
 MECHANICAL OVERSPEED TRIP MECHANISUM

63. CUT VIEW OF ACCESSORY GEAR BOX

64. OTHER SUPPORT SYSTEM
COOLING WATER SYSTEM
FIRE PROTECTION
SEALING AND COOLING AIR SYSTEM

65. COOLING AND SEALING AIR
 PARTS OF THE TURBINE WHICH ARE COOLED BY AIR ARE :
The first and second stage turbine wheel
forward and aft faces.
First and Second stage Nozzles.
Turbine shell and support struts.
Combustion liners.
Transition pieces.
Pressurising the bearing oil seals.

66. COOLING AND SEALING AIR CIRCUIT

68. 4th STAGE EXTRACTION
This air cools the shell surrounding the first
and second stage nozzle , First stage nozzle
and turbine wheels. Also cools the support
struts which are in hot gas stream of
exhaust frame.

69. 10th STAGE EXTRACTION
Air is fed through the second stage nozzle
partition for cooling the aft surface of the
first stage turbine wheel and forward
surface of the second stage turbine wheel.
Seal air for bearing #1 and #2.
To avoid pulsation / surging during start up
/ shutdown

70. SURGING
 Compressor Inlet
Volume Flow is
proportional to Speed
Q ~ N
 Compressor Power is
proportional to third
Power of Speed
P ~ N3
 Total Pressure Ratio
is proportional to
Speed squared
P2 / P1 ~ N2
Fan Laws

71. The Reason for using 10th stage Bleed on this type of
Axial Compressor, can be made more clear when we
look at Compressor running at 100% and 50% of speed
At 100% Speed
IN OUT
V1 = 100 m3/sec V2 = ???
P1 = 1 bar P2 = 11.5 bar
k = 1.4
Poisson’s Law:
P1 x V1
k = P2 x V2
k
1 x 100 1.4 = 11.5 x V2
1.4
V2 = 17.5 m3 / sec
At 50% Speed
IN OUT
V1 = 50 m3/sec V2 = ??
P1 = 1 bar P2 = 11.5 =2.875 bara
k = 1.4 4.0
Poisson’s Law:
P1 x V1
k = P2 x V2
k
1 x 50 1.4 = 2.875 x V2
1.4
V2 = 23.52 m3 / sec

72. Compressor Characteristics with
IGV and 10th Stage Bleed

73. COMPRESSOR 17th STAGE AIR
Channelled internally to the forward surface
of the first stage turbine wheel.
This air flow provides a source of cooling
air for the first stage wheel and is exited into
the exhaust stream.

75. SHROUDS
 Shrouds primary function is to
provide a cylindrical surface for
minimising buckets tip
clearances.
 To provide high thermal
resistance between hot gases and
the comparatively cool shell.
 By accomplishing this the shell
cooling load is drastically
reduced and shell diameter is
controlled.
 Shell roundness is maintained,
and the important turbine
Clearance are assured.
FIRST STAGE
SHROUDS
SECOND STAGE
SHROUDS

76. Spring Seal
Damage
Body Damage
XFT Collar
Damage
Stopper
Damage
Fuel Nozzle
Collar
Damage
TBC Damage
Ovality
POSSIBLE DEFECTS IN COMBUSTION LINERS
Cowl Cap
Damage

77. AFT End bracket
damage
Creep
deflection
AFT End body
damage
Seal damages
TP Body
damage
Spring seal
mark damage
in inner body
Inner / Outer
Slot damage
TBC Coating
damage
Side Slot damage
Possible defects in Transition Pieces

78. COMPRESSOR ROTOR BLADE FAILURE

80. Typical Damage
 Corrosion on leading edge, trailing edge and both side walls.
 Oxidation
 Erosion on the
partitions and
pressure side walls.
 Cracks at both pressure
and suction side of the
segment as well as both
side walls.

81. NOZZLE FAILURE

82. To ensure Unit availability at full potential
performance & to avoid unforeseen failures,
taking in to consideration of the operational
limiting factors, GE has recommended
specified inspection intervals (GER 3620G).
Combustion Inspection
HGP Inspection
Major Inspection.
INSPECTION

84. INSPECTION INTERVALS

85. INSPECTION INTERVALS

86. HGPI HOURS CRITERIA

87. HGPI STARTS CRITERIA

89. COMBUSTION INSPECTION
FUEL NOZZLES
CROSS FIRE TUBES
COMBUSTION LINERS
TRANSITION PIECES
CHECK VALVES SERVICING
BORESCOPIC INPSECTION OF
TURBINE SECTION

90. HOT GAS PATH INSPECTION
COMBUSTION INSPECTION SCOPE +
ALL STAGES NOZZLES AND BUCKETS
SHROUDS
TARNSITION PIECES
NOZZLE DIAPHRAGMS
WHEEL SPACE SEALS
6 POINT CHECK OF COMP. ROTOR

91. MAJOR INSPECTION
HGPI , CI SCOPE +
COMPRESSOR ROTOR AND STATOR
BLADE
ALL BEARINGS
LOAD GEAR BOX
ACCESSORY GEAR BOX
INELT / EXHAUST SYSTEM

92. BORESCOPE INSPECTIONS

93. MAJOR FACTORS INFLUENCING
MAINTENANCE AND EQUIPMENT LIFE
FUEL
FIRING TEMPERATURE
CYCLIC EFFECTS
STEAM / WATER INJECTION
Maintenance COST & Equipment LIFE
are influenced by key SERVICE FACTORS

94. • Fuel Liquid fuel has high bulk
density and releases high
radiant thermal energy.
This would over heat the
parts resulting in early
thermal fatigue failure.
Liquid Fuel contains
impurities (Na, K, Va) which
would accelerate Hot
Corrosion besides erosion.
One hour of liquid fuel
operation is equivalent to 1.5
hours of Gas operation at
base load.0
1
2
3
4
7 9 11 13 15 20
Fuel Percent Hydrogen by Weight in Fuel
IntervalReductionFactor
Residual
Distillates
Heavy Light Natural Gas

95. Permissible Maximum
concentration of contaminants
Fuel, Air and Steam / Water
(Na + K ) < 1 PPM
Pb < 1 PPM
V < 0.5 PPM
Na & K can be desalted, but V
cannot be removed
Mg added to counter it in
Ratio Mg : V :: ( < 3.1 : 1)
Heavier Hydrocarbon Fuel
Release higher
Radiant Thermal Energy
 Contains corrosive elements
Na, K, V and Pb
Accelerates Hot Corrosion
SPECIFICATION of Fuel
Specific Gravity < 0.96%
Water content < 1.00%

96. • Firing Temperature Higher Firing Temperature
(Peak Load) releases higher
thermal energy resulting in
distortions & Creeping of
components.
One hour of peak load
operation is approximately
equivalent to 6 hours of Base
load operation.

97.  INCREASING 56 o C FIRING TEMPERATURE
 OUTPUT increases 8 ~ 13 %
 SIMPLE CYCLE EFFICIENCY increases by 2 ~ 4 %

98. • Cyclic effects Normal cyclic operation of
start, operation & shutdown
itself can cause cyclic stress,
the severity is phenomenal
in the case of emergency
start & trips. This would
result in cracks more so in
combustion parts.
One emergency trip cycle is
approximately equivalent to
8 normal shutdown cycles.

99. CYCLIC EFFECTS
 Temperature responds
quickly on edges
 Results in Thermal
stresses
 Compressive strain
during start-up
acceleration and also
at Full load
 Tensile strain
during shut down

101. Steam / Water Injection
Steam or Water Injection used
for control of emission or
augmented power causes
higher dynamic pressure and
higher transfer of heat to
Bucket & Nozzle resulting in
higher metal temperature of
these components.

102. STEAM / WATER INJECTION
PURPOSE
For emissions control
Power augmentation
CHANGES HEAT TRANSFER
PROPERTIES
Higher Gas Conductivity .
. . Higher Heat Transfer
. . Higher Metal Temp . . .
. . . Reduced Part Life

104. PURPOSE OF COATINGS ON GT COMPONENETS
• Protection against erosion and hot corrosion.
• Enhance the surface properties of base material.
• Provide an Insulating Layer that reduces the
underlying base material temperature.

105. COATINGS ON GAS TURBINE COMPONENTS . . .
COMPRESSOR
COMPONENTS
COMBUSTION
COMPONENTS
HOT GAS PATH
COMPONENTS
GECC -1 Coating – GE Cold
Coating on Blades for
Corrosion Resistance

106. AISI 403 STAINLESS
SACRIFICIAL
UNDER COAT
CERAMIC
TOP COAT
TwoLayer System
Base Coat:Aluminum Filled Base Material
ForOxidation Protection
TopCoat :Ceramic
ForCorrosion Resistant
GECC1 ROTOR COATING . . .
}3 Mils thick

107. Benefits
Extend ComponentLife
Longer Lasting Compressor Efficiency
Fouling hasless tendency tostick
Easier to remove fouling
Protect parts from Environment during
prolonged periods of Inactivity
GECC1 ROTOR COATING . . .

108. GECC1coatingon Rotor
• Assembledrotors
• Un-stackedrotors
Blade &Wheels
StatorBlades
IGVs
GECC1 ROTOR COATING . . .

109. COATINGS ON GAS TURBINE COMPONENTS . . .
COMPRESSOR
COMPONENTS
COMBUSTION
COMPONENTS
HOT GAS PATH
COMPONENTS
TBC COATING
ID of Combustion Liners AND
Transition Pieces
HARD FACE COATING
Mating surfaces of :
X fire tube & X fire tube collar
 Fuel Nozzle & Nozzle collar
 Fuel Nozzle Tip, Bull Horns

110. “NiCrAlY Coatings”
followed by CERAMIC
(Zirconia, ZrO2)
 MCrAlY increase the
adherence of the oxide
layer to the substrate
(base Ni alloy)
COMPOSITION
MCrAlY (M = metal) based bond coating
18% Chromium,
22% Cobalt,
12% Aluminum and
0.5% Yttrium
Temperatures in Gas
Turbine around 1350°
Melting point of these
Nickel alloys is about
(1200~1315°C)!

112. COATINGS ON GAS TURBINE COMPONENTS . . .
COMPRESSOR
COMPONENTS
COMBUSTION
COMPONENTS
HOT GAS PATH
COMPONENTS
• Diffusion Coating Pt-Al (up-to 1983) ( Electroplating of ---
……….Platinum 0.006 mm > Al by Diffusion Packing )
• PLASMAGUARD GT-29 / GT-29 PLUS / GT-29 IN-PLUS
• GT-33 IN-COAT™ and GT-33 IN-PLUS™
•PLASMA GUARD GT-43 / GT-20 (low temperature) for SHROUDS

114. Coatings on Shrouds …… see the difference
with uncoated shrouds
HOT GAS PATH COMPONENTS . . .

115. MATERIAL OF CONSTRUCTION
 Combustion Liner
 Transition Piece
 1st Stage Nozzle
 1st Stage Bucket
 2nd Stage Nozzle
 2nd Stage Bucket
 IGV’s
 Compressor Rotor Blades
 Compressor Stator Blades
 RA-333
 Hastelloy-X
 Hastelloy-X
Nickle-base super alloy
o FSX-414
Cobalt-base super alloy
 GTD-111/GT-29+Coating
Nickle-base super alloy
 N-155 Iron-base super alloy
 U-500 Nickle-base S-Alloy
 GTD-450
Precipitate Hardened Martensitic Steel
o GTD-450 / AISI-403
o AISI-403

117. THANKS