8/20/2019 GE MS 900 Series
1/18
GER-3928A
UPRATE OPTIONS FOR THE
MS900A HEAVY-DUTY GAS TURBINEJennifer E. Gill
GE Power Systems
Schenectady, NY
ABSTRACTThe GE MS9001 heavy-duty gas turbine has gone
through a series of uprates since its original
introduction to the market in 1975. These uprates are
made possible by technology advances in the design
of new machines based on information accumulated
through tens of thousands of fired hours, new
materials and GE’s continuing research.
This paper will discuss evolutionary design
advances in critical components for the GE MS9001
series of turbines. It will also discuss how the latest“E” technology advances can be applied to enhance
the performance, extend the life and provide
economic benefits by increased reliability and
maintainability of all earlier MS9001B and
MS9001E turbines.
The following “E” technology uprate packages
will be described:
• MS9001 “B to E” turbine uprates
• MS9001E firing temperature increase to
2020°F/1104°C
• MS9001E firing temperature increase to
2055°F/1124°C
The paper also describes options for reducing
emissions, tradeoffs and expected reductions, and,
GE programs for uprating, either as a single project
or phased in over time.
INTRODUCTIONThe past decade has seen unprecedented pressures
on both utilities and independent power producers to
hold the line on new investments, to become more
effective in operations and maintenance, and to bemore efficient in producing power. Modernizing and
uprating their installed fleet of turbines is emerging
as an economically attractive solution. An uprate
offers these benefits:
• Performance improvements in output and heat
rate
• Extension of inspection intervals while
shortening their duration
• Availability and reliability improvements
• Emission reductions
GT25018
Figure 1. MS9001E Simple-Cycle single-shaft heavy-duty gas turbine
8/20/2019 GE MS 900 Series
2/18
GER3928A
2
• Life extension
Uprates are made possible as a result of GE’s
underlying design philosophy which is to maintain
interchangeability of components for a given frame
size such that components can be installed in earlier
vintage units with little or no modifications. Installing
the latest technology hardware and taking advantange
of the highest firing temperatures allowsowners/operators to remain competitive in the
marketplace. Virtually every key component in the
MS9001 series has gone through significant design
improvements since the first MS9001B was shipped
in 1975. Buckets, nozzles, shrouds and combustion
components have undergone multiple evolutions
based on new designs, manufacturing techniques,
materials and field experience. Figure 1 illustrates the
basic MS9001E configuration.
Uprates make very good investments, with most
exhibiting prompt payback. Each turbine application
must be evaluated on its own merits, but paybacks
under two years have been registered. Uprates can be
phased in according to the outage schedule, or
installed in a single outage, with appropriate advance
scheduling.
Gas Turbine reference codes (e.g., FT5X for an
MS9001 B to E advanced technology uprate have
been added to the text and to many of the figures and
tables for easier correlation to other published
information on specific uprate packages or
components.
MS9001 HISTORYThe first MS9001, shipped in 1975 as a model
MS9001B for the 50 Hz market, incorporated design
experience from the successful MS7001B. Operating
with a design firing temperature of 1840 F/1004 C
(base load), the same firing temperature as the
MS7001B, the MS9001B design represented an
increase of 42% in output over the MS7001B. This
introductory design incorporated the air-cooled stage
1 buckets and nozzles and stage 2 bucket material
improvements based on the MS7001B design
experience gained prior to 1975. As seen in Figure 2,
the output of the MS9001 has increased by 45% based on technology improvements through 1994, not
including the EC or F/FA product lines.
Introduced in 1978, the MS9001E, incorporated
the experience gained from MS7001E production and
operation as well as the design improvements that
had evolved since the MS9001B was first introduced.
The introductory firing temperature was
1955°F/1068°C.
As apparent from performance increases, the
MS9001E has seen many design improvements since
it was introduced as an MS9001B, with one obvious
change being the increased firing temperature.
Advances in materials, coating and cooling
technology have supported a series of firing
temperature increases. The current firing
temperature of the latest MS9001E is
2055°F/1124°C. All earlier vintage MS9001E gas
turbines can be uprated to the 2055°F/1124°C firing
temperature.
CURRENT MS9001E
COMPONENT TECHNOLOGYProduct technology derived from ongoing new
product development, field service reports and new
materials and techniques has resulted in
improvements to combustion liners, transition pieces,
high flow inlet guide vanes and all stages of buckets,
nozzles and shrouds.
The component improvements can be applied
individually or as a complete uprate package,
depending on schedule, budget and machine
condition. Design improvements and rationale will be
described, as well as their effect on performance andmaintenance.
COMBUSTION SYSTEM
COMPONENTSEfforts to advance the combustion system are
driven by the need for higher firing temperatures and
for compliance with regulatory requirements to
reduce exhaust emissions. Relatively simple parts in
PG9111B
PG9141E
PG9157E
PG9151E
PG9161E
PG9171E
PG9231EC
PG9301F
PG9311FA
GT18469 “I”
1975-81
1978-81
1981-83
1983-87
1988-91
1991
1996
1993-94
1994
ModelShip
Dates
85,200
105,600
109,300
112,040
116,930
123,450
165,700
209,740
223,760
ISOPerformance*
kW
*Base Load Distillate Fuel, Includes 0/0 Inches H2O Inlet/Exhaust Pressure Drops
1840/1004
1955/1068
1985/1085
2000/1093
2020/1104
2055/1124
2200/1204
2300/1260
2350/1288
FiringTemp. °F/°C
2.736/1.241
3.155/1.431
3.183/1.444
3.214/1.458
3.222/1.461
3.231/1.466
4.044/1.834
4.804/2.179
4.819/2.186
Air Flow(106 lbs/hr 106 kg/hr)
10,990/11,592
10,700/11,286
10,700/11,286
10,570/11,149
10,290/10,854
10,080/10,632
9,870/10,411
10,080/10,632
9,630/10,158
Heat Rate(Btu/kW/hr kJ/kWh)
945/507
953/512
968/520
977/525
980/527
998/537
1,037/558
1,082/583
1,097/592
ExhaustTemp. °F/°C
Figure 2. MS9001 Performance History
8/20/2019 GE MS 900 Series
3/18
GER-3928A
3
early gas turbines are now complex hardware pieces
with sophisticated materials and processing
requirements. Combustion system upgrades can be
supplied as a package or as individual options.Depending on the option chosen and other machine
conditions, upgraded combustion system components
produce substantial improvements in component life
and/or for extensions in recommended combustion
inspection intervals.
Combustion Liners (FR1G/FR1H)
The MS9001B/E series consists of 14 combustion
chambers. The original combustion liner on the
MS9001B was the louvered liner, which was cooled
through louvered punches in the liner body. The body
could experience cracking due to stresses inherently
introduced during the manufacturing process. The
louvered liner was replaced with a slot-cooled liner
with the introduction of the first MS9001E. Both
liners are shown in Figure 3. The slot-cooled liner
provides a more uniform distribution of cooling air flow for better overall cooling. Air enters the cooling
holes, impinges on the brazed ring and discharges
from the internal slot as a continuous cooling film.
The liner material is Hastelloy-X, a nickel-base
alloy, which has not changed since the introduction of
the MS9001B in 1975. Today, however, a thermal
barrier coating (TBC) is applied to the liners. The
TBC consists of two materials applied to the hot side
of a component (Figure 4): a bond coat applied to the
surface of the part and an insulating oxide applied
over the bond coat. This TBC provides a 0.015-inch
insulating layer that reduces the underlying base
material temperature by approximately 100°F/38°C.
The addition of TBC also mitigates the effects of
uneven temperature distribution across the metal.
With the MS9001E firing temperature increase to
2055°F/1124°C, the thickness of the liner was also
increased by approximately 10 mils to accommodate
the higher temperatures.
Transition Piece (FR1D)
GT24927.ppt
Slot-CooledLiner
LouveredLiner
Figure 3. Improved slot-cooled liner vs. original
louvered liner
Liner
GT11701D
Coating Microstructure
Top Coat
Bond Coat
Figure 4. Thermal barrier coatings 1
8/20/2019 GE MS 900 Series
4/18
GER3928A
4
The original 9B combustion system was a parallel
system, with the combustion liner parallel to thecenterline of the rotor. When the first 9E was
developed, the combustion system was redesigned.
The redesigned system was a “canted” system
consisting of a shorter transition piece and the slot-
cooled liner. Shortening the length of the “transition”
section of the transition piece increased its stiffness.
The canted design reduced the angle through which
the combustion gases had to flow, thus providing a
more direct flow path. The canted design made it possible to shorten the transition section of the
transition piece, and therefore shorten the overall
length of the transition piece.
When the firing temperature was increased to
2055°F/1124°C, the “canted” arrangement was
upgraded to the “canned” arrangement. The “canned”
arrangement consists of a longer transition piece with
a thicker slot-cooled liner, as previously mentioned.
The longer transition piece essentially pushes the
liner out of the wrapper. Outer combustion casings as
seen in Figure 5. The transition piece was lengthened
by adding a 15-inch long cylinder to the forward end.
While the transition piece length was increased, the
curved section remained the same, thereby retaining
its stiffness. The transition piece was lengthened to
relocate the transition piece-liner interface, in order to
minimize wear induced by the compressor discharge
flow. Figure 5 illustrates the differences between the
current 9E production “canned” arrangement, the 9E
“canted arrangement and the 9B parallel combustor.
Early 9B turbines utilized a thin-walled transition
piece constructed of Hastelloy-X material. The
original 9E transition piece was a thick- walledHastelloy-X. In the mid 1980s, the transition piece
MS9001B Parallel Arrangement
MS9001E Canted Arrangement
GT25006.ppt
MS9001E Canned Arrangement
Figure 5. MS9001 combustion system comparison
Old Design Aft Bracket
GT21369A.ppt
Redesigned Aft Bracket
TransitionPiece
TransitionPiece
AftEnd
Figure 6. Comparison of transition piece aft bracket
8/20/2019 GE MS 900 Series
5/18
GER-3928A
5
material was changed to Nimonic 263 which is a
nickel-base alloy with better strength characteristics
than Hastelloy-X. Nimonic 263 demonstrated
superior creep life and could increase the inspection
interval to 12,000 hours. The Nimonic 263 transition
pieces are coated with thermal barrier material,
thereby reducing metal temperatures and increasing
component life.
The Nimonic 263 transition piece has a positive
curvature body and aft bracket that reduces cracking
at the bracket weld area by allowing the transition
piece to pivot about the pin during thermal cycles. Acomparison of the original and redesigned aft bracket
design is shown in Figure 6.
GE has recently designed a new Nimonic transition
piece for the MS9001B to provide a substantial
increase in creep strength over the current design.
The uprate potential of the current MS9001B
machines is limited by the inability of the current
transition piece to withstand higher firing
temperatures. This improved transition piece enables
these units to be uprated beyond their current rated
firing temperature. Additionally, this improved
transition piece is required for these units to realize
the full benefits of the Extendor™ Combustion
System.
Extendor™ Combustion System
(FR1V/FR1W)
All GE heavy-duty gas turbines require periodic
combustion inspections due to TBC coating erosion,
wear and material creep. GE has developed a product
– Extendor™ – to increase combustion inspection
intervals. The Extendor™ combustion system, shown
in Figure 7, decreases combustion component wear
and increases combustion inspection intervals by
reducing the relative movement and associated wear
of parts in the combustion system. Application of the
Extendor™ wear system extends transition piece
inspection intervals up to 24,000 hours. Figure 8
details the improved combustion wear inspection
intervals.
Customer savings occur with the elimination of labor costs associated with combustion inspections
and reduction of component repair costs. Extendor™
can be applied as a component modification during
routine maintenance or as a complete retrofit.
Extendor™ is currently available for MS9001 series
gas turbines with slot-cooled liners and Nimonic
transition pieces.
Dry Low NOx Combustion System
(FG2B)
Customers without diluent supplies for injection
purposes can achieve NOx emission requirements
through the use of Dry Low NOx combustors. The
DLN combustion system for the MS9001E is shown
in Figure 9. The DLN combustion system reduces
NOx emissions without steam or water injection on
gas fuel units. This is done by fuel staging, with lean
fuel to air ratios dependent upon premixing fuel with
Fuel Nozzle toFloating Collar
Crossfire Tube,Retainer & Stop
T/P H Block toBullhorn
TransitionPlace SealFrame
Liner Hula Sealto TransitionForward Sleeve
GT20550
Figure 7. ExtendorTM combustion system
8/20/2019 GE MS 900 Series
6/18
GER3928A
6
hot compressor discharge air to yield lower
temperature rises across the combustor.
The DLN combustor (Figure 10) has six
individual fuel nozzles in the primary combustion
zone, and a single fuel nozzle in the secondary
combustion zone. The DLN combustion system
offers lower NOx emission levels on gas fuel-fired
units without parts life reduction associated withwaer or steam injection NOx reduction systems.
Emission levels of 15 ppmvd at 15% O2 or less can
be reached by using the DLN combustion system.
TURBINE COMPONENTSThere have been significant design and material
improvements made to the turbine components since
the first MS9001B was manufactured. The improved
component designs can withstand higher firing
temperatures due to advanced materials and coatings,
as well as the addition of air cooling for some of the
components. This section will describe the evolution
of these technologies. The latest technology
components now used in current production
MS9001E can be retrofitted to earlier models.
BUCKETS
Stage 1 Bucket (FS2H)
Four major changes have been made since the
original MS9001B stage 1 bucket was introduced.
Design.
The original design’s sharp leading edge has been
blunted to allow more cooling air to flow to the
leading edge, which reduces thermal gradients and,
therefore, cracks. The Blunt Leading Edge (BLE)
design, shown in Figure 11, was used as the first
MS9001E stage 1 bucket.
Materials.
The original MS9001B stage 1 bucket was IN-738, a precipitation-hardened, nickel-base super
alloy. In 1987, the material was changed to an
Equiaxed (E/A) GTD-111, also a precipitation-
hardened, nickel-base super alloy, a greater low cycle
fatigue strength than IN-738. GTD-111 also provides
the industry standard in corrosion resistance.
Coatings.
Lean andPremixing
Primary Zone
Secondary
Fuel Nozzle(1)
PrimaryFuel Nozzles
(6)
GT15050B
Dilution ZoneSecondary Zone
Centerbody
Venturi
End Cover
Outer Casing Flow Sleeve
Figure 10. Dry Low NOx combustor
GT25007A
Flow Sleeve
Case,
Combustion
Outer
Wrapper
Primary Fuel Nozzle &
Combustion Cover
Assembly
Secondary Fuel
Nozzle Assembly
Compressor Discharge Casing
Transition
Piece
Figure 9. MS9001 dry low NOx combustion system
Combustion Liners
Transition Pieces - Thin Wall
- Thick Wall
- Nimonic
Hot Gas Path
Major
Significant Savings in Maintenance CostGT25218
3,000
3,000
8,000
12,000
24,000
48,000
8,000
----
8,000
12,000
24,000
48,000
24,000
----
----
24,000
24,000
48,000
9B Extendor TM9E
Hours
Figure 8. Typical MS9001B vs. MS9001E
maintenance
Original Designand ThermalGradients
GT21321A.ppt
Blunt Nose BucketWith ImprovedThermal Gradients
Figure 11. Sharp and blunt leading edge bucket
design comparison
8/20/2019 GE MS 900 Series
7/18
GER-3928A
7
The first 9E bucket coating, platinum aluminide,
was applied to stage 1 buckets in order to preventoxidation and corrosion. In 1991, with the addition of
turbulated cooling holes, the bucket coating was
changed to GT-29 INPLUS. This coating is a
vacuum plasma spray with an aluminide coating on
the bucket exterior and the internal cooling hole
passages. In 1997 the coating was changed again to
GT-33 INCOAT. GT-33 is a vacuum plasma spray
coating like GT-29, but offers an increased resistance
to through cracking. “INCOAT” refers to an
aluminide coating on the cooling holes passages.
GT-33 INCOAT is GE’s new standard coating for
stage 1 buckets, however GT-29 INPLUS is stillavailable and is recommended when burning
corrosive fuels.
Stage 2 Bucket (FS2F)
The stage 2 bucket has changed significantly since
the original bucket was introduced.
Cooling.The original MS9001B stage 2 bucket did not
have internal air cooling. The MS9001E design
contains air-cooled stage 2 buckets, as shown in
Figure 12. The addition of air cooling allows for
higher firing temperatures. In order to replace non
air-cooled stage 2 buckets with the new air-cooled
buckets, the 1/2 wheel spacer must be replaced with
the new design that allows air to flow to the stage 2
bucket.
This bucket can be supplied without internal
cooling air passages as a direct part replacement for
the MS9001B. With this option, the 1/2 wheel spacer would not have to be replaced. While lower in cost,
the non-air-cooled version of this bucket would not be
able to withstand an increase in firing temperature
above 1905°F /1040°C.
Tip Shroud.
The shroud leading edge was scalloped (Figure
13), the shroud tip was thickened between the seal
teeth, and the underside of the shroud was tapered.
Scalloping the leading edge decreased the stress at the
top of the fillet. The final design (Figure 14) resultedin a 25% reduction in stress levels and an 80%
increase in creep life over the original design.
GT24908.ppt
Core Plug
EnlargedView A-A
CoolingHole
A A
Figure 12. MS9001E stage 2 air-cooled bucket
GT21361A
Figure 13. Scalloping of bucket shroud
8/20/2019 GE MS 900 Series
8/18
GER3928A
8
The most recent design change added cutter teeth
to the bucket tip rails. These cutter teeth were
designed for use with the new Honeycomb stage 2
shrouds. The “twisted rail” design cutter teeth,
standard on all new stage 2 buckets, essentially
rotates the tip rails by 0.5 degrees, causing the tip
rails of each bucket to be offset relative to the
preceding and subsequent buckets. This offset createsthe cutter tooth. required with honeycomb shrouds.
During transients when the bucket tip clearance is the
smallest, the cutter teeth cut a path through the
honeycomb material in the shroud, thus minimizing
the steady-state clearance. Stage 2 buckets with
cutter teeth are required for use with honeycomb
shrouds, but can also be used with the traditional
design shrouds. Cutter teeth can also be applied to
buckets in good condition with fewer than 48,000
hours of operation in a qualified service shop.
Materials.
The original bucket was made of U-700, a
precipitation-hardened, nickel-base alloy. Since then,
there have been two changes to the bucket material.
For early MS9001E production, the material was
changed to IN-738, a precipitation-hardened, nickel-
base super alloy which provided an increase in
elevated temperature strength and hot corrosion
resistance. In 1992, the material was changed to
GTD-111, also a precipitation-hardened, nickel-base
super alloy, to improve rupture strength. In addition
to a higher rupture strength, GTD-111 has higher low-cycle fatigue strength.
Coating.
With the change in material to GTD-111, GT-29
INPLUS coating was added. INPLUS coating refers
to PLASMAGUARD GT-29 with an overaluminide
aluminide coating on the internal cooling passages.
Like the stage 1 bucket, the standard coating was
changed to GT-33 INCOAT in early 1997. GT-33
INCOAT consists of GT-33, a vacuum plasma spray
coating, on the exterior of the bucket and an
aluminide coating on the interior of the cooling hole
passages. GT-33 INCOAT provides superior
through crack resistance relative to GT-29 INPLUS.
GT-29 INPLUS is still available and is recommended
for use in corrosive fuel applications.
Stage 3 Bucket (FS2K)
The MS9001B stage 3 bucket has experienced
changes in design, manufacturing process and
material.
Design.
With the introduction of the 9E, the airfoil was
rotated to take advantage of the additional airflow.
The airfoil was further rotated in 1991 as part of theuprate program. These rotations are the basis of the
performance improvements shown in Figures 35 and
36.
The trailing edge was thickened, and the chord
length increased. Like the stage 2 buckets previously
described, the shroud leading edge was scalloped, the
shroud tip was thickened between the seal teeth, and
the underside of the shroud was tapered. These design
changes resulted in an increase in creep life of the
bucket.
Like the stage 2 buckets, the most recent change
was to add cutter teeth to the bucket tip rails. Thesecutter teeth are required for use with stage 3
honeycomb shrouds, as previously described. Current
production stage 3 buckets include cutter teeth.
Cutter teeth can be added to the stage 3 buckets in
good condition with fewer than 48,000 hours of
operation in a qualified service shop.
In order to use the 9E bucket on a 9B machine, the
stage 3 shrouds must be replaced or modified. Figure
15 illustrates the machining points on the shroud
which is required for the modification. Additionally,
due to interference with the angel wing,owners/operators may elect to machine the exhaust
frame to facilitate rotor removal, however it is not
required.
GT21362A
Figure 14. Final configuration of bucket shroud
8/20/2019 GE MS 900 Series
9/18
GER-3928A
9
Process Change.
The original MS9001B stage 3 bucket was cold
straightened after being cast, inducing strain in the
material. The combination of the induced and creep
strains resulted in potential creep-rupture cracks,
further propagated by high-cycle fatigue. GE
developed a new manufacturing process for theMS9001E bucket which eliminates the need for the
cold straightening step, thus eliminating the process-
induced strain in the material.
Materials.
Bucket material has recently been improved. The
stage 3 bucket was originally made of U-500, a
precipitation-hardened, nickel-base alloy. To improve
elevated temperature strength and hot corrosion
resistance, the bucket material was changed in 1992to IN-738, a precipitation-hardened, nickel-based
super alloy.
NOZZLES
Stage 1 Nozzle (FS2J)
The MS9001 stage 1 nozzle has evolved through
four generations, each improving on the preceding
one, starting with the MS9001B 4-vane nozzle. The
second generation, designed for the MS9001E, was
used primarily for clean fuel applications. The third
generation – the Universal Fuel Nozzle – was
significant because it is applicable for gas, distillate
and ash-bearing fuels. The fourth generation, known
as the Chordal Hinge Nozzle, incorporated GE
Aircraft Engine technology as well as improved
Modify Existing Third Stage Shroudsas Shown Above.
1
1
GT24909.ppt
Figure 15. Machining required on stage 3 shroud
GT25005
9E Clean FuelStage 1 Nozzle
9E Universal FuelStage 1 Nozzle
9B Stage 1 Nozzle 9E Chordal HingeStage 1 Nozzle
Figure 16. Comparison of 9B and 9E stage 1 nozzles
8/20/2019 GE MS 900 Series
10/18
GER3928A
10
cooling and sealing technology. This section will
discuss the design improvements brought about in
each generation. A comparison of the cross-sections
of each generation is shown in Figure 16.
Several design modifications were made to the
original MS9001B stage 1 nozzle to develop the
MS9001E clean fuel stage 1 nozzle. One of the most
dramatic changes was made in response to the vanefillet cracking problem (Figure 17) caused by high
thermal stress induced by the high thermal gradient
across the sidewall/vane interface. By decreasing the
number of vanes per segment, structural redundancy
and the thermal stresses were reduced, thus
minimizing the vane fillet cracking. The original 9B
stage 1 nozzle had four vanes per segment and
required 12 segments. The clean fuel nozzle has only
two vanes per segment with a total of 18 segments.
As illustrated in Figure 16, the interface between the
support ring and nozzle was moved downstream.
At the same time that the number of vanes per
segment was reduced, the shape of the airfoil was
optimized and the vanes were rotated to reduce the
throat area. The new airfoil shape and reduction in
throat area increased the pressure ratio. Installing thisdesign into an MS9001B can increase the pressure
ratio by as much as 6%.
The suction side wall thickness of the nozzle
airfoil at the pitch section was increased by 13%,
which effectively reduced the aerodynamic-induced
mechanical stress and increased the creep life of the
part. The stress level was further reduced by the
addition of an internal center rib. The center rib is
shown in Figure 18.
The Universal Fuel Nozzle was developed from
the clean fuel nozzle in response to the need to burn
residual fuels, as well as clean fuels. The airfoil
shape was rounded making it more blunt and the
entire cooling system was redesigned. The pressure
side cooling holes were replaced with slots and placed
closer together to provide more uniform
cooling(Figure 19). Trailing edge cooling was also
added as seen in Figure 19. This improved cooling
design decreased surface metal temperature by as
much as 5% thus minimizing cracking, airfoil
ballooning, and trailing edge bowing.
The nozzle support ring interface was moved
FilletCracks
Outer Sidewall
GT21363A
Flow
Inner Sidewall
Figure 17. Cracked center stage nozzle 1
Center Rib
Core Plugs
GT24913
Figure 18. Stage 1 nozzle airfoil pressure side film
cooling modification
Modified SlotPattern
Old HolePattern
Trailing EdgeCooling Holes
Core Plugs
Center Rib
Suction SideFilm Cooling
Holes
Pressure SideFilm Cooling
Holes
• Pressure Side Film Holes Replaced With Slots to Provide Better Coverage− Closer Spacing− Better Exit Condition
• Modification Introduced With OSW Cooling Redesign
GT24924
Figure 19. Stage 1 nozzle airfoil pressure side film cooling
8/20/2019 GE MS 900 Series
11/18
GER-3928A
11
further downstream in line axially with the nozzle-
retaining ring interface. This change was
implemented to minimize torsional forces exerted on
the sidewall near the nozzle-retaining ring interface.
In 1992, a tangential support lug consisting of an
integrally cast side support lug with a milled radial
slot was introduced to the stage 1 nozzle inner sidewall. A support pin and bushing were also added to
secure the nozzle segment. A lockplate and a single
retainer bolt were used to keep the support pin in
place. This arrangement provided additional
tangential support for the nozzle.
The forth and current generation of stage 1 nozzle
is the chordal hinge nozzle introduced in 1994. This
nozzle is the result of two major design changes
maintaining the philosophy of burning both clean and
heavy fuels. The first design change was made to
reduce the leakage between nozzle segments and between the nozzle and support ring. The chordal
hingewhich incorporates the latest in GE Aircraft
Engine sealing technology, was added. The chordal
hinge refers to a straight line seal on the aft face of
the inner side wall rail which ensures that the seal is
maintained even if the nozzle rocks slightly. The
chordal hinge and the new sidewall seal design are
illustrated in Figure 20. The chordal hinge reduces
the leakage between the nozzle and the support ring.
The leakage between the nozzle segments was
decreased by improving the sidewall, or spline seals.
The second major change was to improve the
sidewall cooling. As the firing temperature increased
over the development of the MS9001E, the nozzle
was exposed to higher temperatures, causing
oxidation and erosion to occur on the sidewalls. Toreduce the oxidation and surface erosion, the cooling
effectiveness was increased. The overall cooling
effectiveness was improved by relocating some of as
seen in Figure 21.
When the chordal hinge nozzle was introduced, the
original tangential pin hardware was replaced with a
single piece bushing/tangential pin to secure the
nozzle and a flat lockplate with two retainer bolts
was used to keep the bushing/tangential pin in place
(Figure 22). More recently the tangential pin
hardware has been eliminated–field inspections haveindicated that the hardware is not required. In
addition to eliminating the hardware, the forward
flange on the support ring has been eliminated
(Figure 23). These design modifications make the
universal nozzle and chordal hinge nozzle completely
interchangeable with no support ring modifications
required.
As seen in (Figure 16), the 9B stage 1 nozzle and
the 9E clean fuel nozzle support ring interface is
Final DesignPresent Design
HookMachining
Relief
Improved
Seal
Chordal HingeSeal
GT24932Lug Maching Relief
Figure 20. Stage 1 nozzle improved sidewall sealing with chordal hinge
8/20/2019 GE MS 900 Series
12/18
GER3928A
12
located further upstream than either the Universal or
Chordal Hinge stage 1 nozzle. Therefore, to install
the chordal hinge stage 1 nozzle in a unit that
currently has the 9B stage 1 nozzle or the 9E clean
fuel nozzle, a new support ring must also be
provided. As previously mentioned, when installing
the chordal hinge stage 1 nozzle in a machine that
currently has the Universal stage 1 nozzle, a newsupport ring is not required because the location of
the support ring interface is the same for both
designs.
Throughout the development of the MS9001 stage
1 nozzle, the nozzle material, FSX-414, has not been
changed. FSX-414 is a cobalt-base super alloy which
provides excellent oxidation, hot corrosion and
thermal fatigue resistance, and has good welding and
casting characteristics. This material’s superior
properties warrant its continued use in this
application.
Stage 2 Nozzle (FS1P)
The original MS9001B stage 2 nozzle had a
tendency to creep as reflected in the tangential
downstream deflection (Figure 24), resulting in more
frequent nozzle repairs. In order to minimize the
tangential deflection, a series of design changes were
implemented. The first step was to add internal core
plug air-cooling to the nozzle, which resulted in a
decrease in metal surface temperature. All MS9001E
units have air-cooled stage 2 nozzles.
The next major change was to increase the chord
length (Figure 25), which reduced stress levels in the
vanes and improved creep resistance. In late 1991,
the original nozzle material (FSX-414) was replaced
with GTD-222, a nickel-base alloy previously
described, because of its superior creep strength.
Figure 26 provides a comparison of the nozzle creep
deflection of GTD-222 and FSX-414. An aluminide
coating was added to protect against high
temperature oxidation.
With the material change to GTD-222, less
cooling flow for the nozzle was required, due to thematerial’s superior high temperature creep properties.
The cooling was decreased by inserting a longer
tuning pin in the stage 1 shroud and decreasing the
size of the cooling hole in the aft face of the shroud.
For better distribution of cooling air, the nozzle core
plug was redesigned and the size of the pressure side
cooling holes was decreased. Reducing the cooling
flow yields an increase in output. The MS9001E will
see an increase in output of approximately 1.0% with
either the one- or two-piece stage 1 shroud with new
tuning pins in conjunction with the GTD-222 stage 2
nozzle. (The original one piece shroud must have the
aft cooling hole size reduced in order to realize the
full performance benefit). Because the existing
MS9001B stage 2 nozzle is not air cooled, installing
this air-cooled stage 2 nozzle will result in an output
loss of approximately 1.0% due to the air extractedfrom the system for cooling airflow.
8/20/2019 GE MS 900 Series
13/18
GER-3928A
13
GE is currently developing a brush seal for the
stage 2 nozzle diaphragm based on the success of the
High Pressure Packing and No. 2 bearing brush
seals. The seal between the diaphragm and the 1-2
spacer regulates the amount of cooling air flow
between the first aft and the second forward
wheelspaces. The current seal is a labyrinth seal with
a series of short and long teeth on the diaphragm and
high and low lands with teeth on the spacer. Thestage 2 nozzle cooling air comes in through the stage
1 shroud and enters the nozzle core plug via the
plenum formed between the outer sidewall of the
nozzle and the turbine shell. The air flows through
the nozzle core plug; some of the air exits the nozzle
via the trailing edge cooling holes and the remainder
of the cooling air flows into the cavity between the
diaphragm and the nozzle. This air flows to the first
aft wheelspace and through the diaphragm/spacer
seal (inner stage packing) to the second forward
wheelspace.
Our experience on MS7001 and MS9001 gas
turbines shows that these wheelspace temperatures
run significantly cooler than the design limit. Based
on this experience, the cooling flow can be reduced
providing additional output without affecting parts
life. The brush seal design will utilize a brush seal in
place of the middle long tooth on the diaphragm. This
brush seal is expected to provide a performance
improvement due to the reduction in cooling flow.
This design is currently being tested on an
MS7001EA; test results should be available by the
end of 4Q 1997. The stage 2 nozzle diaphragm
brush seal for the MS9001E will be available by 3Q
1998.
Stage 3 Nozzle (FS1R)
The original stage 3 nozzle, like the stage 2 nozzle,experienced tangential deflection. In order to decrease
the tangential deflection, thus minimizing the creep,
three design changes were made. First, the chord
length was increased to reduce overall airfoil stress
levels. Secondly, an internal airfoil rib, similar to the
one for the stage 1 nozzle, was added to provide
additional stability and increase the component’s
buckling strength. Finally, in 1992, the material was
changed from FSX-414 to GTD-222. Unlike the
stage 2 nozzle, an aluminide coating is not necessary
due to lower temperatures seen in stage 3. Since this
nozzle is not aircooled there is no performance benefit like the stage 2 nozzle.
SHROUD BLOCKS
Stage 1 Shroud Blocks (FS2C)
The stage 1 shroud block was redesigned for the
MS9001E 2055°F/ 1124°C firing temperature uprate
Film Cooling Relocated to Cover Distressed Area
GT24895
Current Design Redesign
Figure 21. Stage 1 nozzle improved outer sidewall film cooling
8/20/2019 GE MS 900 Series
14/18
GER3928A
14
program in 1991 (Figure 27) and consists of two
pieces rather than one. The original one piece design
did not provide adequate LCF life at the higher firing
temperature. The two piece design is film cooled
using airflow from the stage 2 nozzle to inhibit
cracking. The film cooling required additional flow
which translates into a performance loss. This
performance loss can be regained by installing theGTD-222 stage 2 nozzle with the appropriate tuning
pins for the stage 1 shroud. The two-piece stage 1
shroud design is only required for the
2055°F/1124°C firing temperature.
The main advantage of the two piece design is that
it allows the damaged caps to be replaced without
having to remove the shroud block bodies or turbine
nozzles. Each piece of the shroud block is made of a
different material. The body and hook fit are made of
310 stainless steel and the cap is made of FSX-414.
GE is currently developing a new one piece design
shroud to regain the lost performance associated with
the two piece design. This new shroud will be made
of Haynes HR-120 which, in conjunction with some
design modifications to the original one piece design,
will provide sufficient LCF life at 2055°F firing
temperature. The new design will also incorporate
improved inter-segment seals to reduce leakage. This
material is used in the latest design stage 1 shroud for
the MS6001B as well as the MS7001EA. This
design will be available in early 1998.
Stage 2 and 3 Shroud Blocks (FS2Tand FS2U)
Stage 2 and 3 shroud blocks provide bucket tip
sealing. The original seal was labyrinth seal. In an
effort to provide better sealing in this area,
honeycomb material was recently applied to both the
stage 2 and 3 shrouds. Honeycomb seals are designed
to reduce bucket tip leakage, resulting in an
improvement heat rate and output. Honeycomb
shrouds are illustrated in Figure 28.
Honeycomb will allow contact between the bucket
tip and casing shrouds during transient operation and
will provide relatively tight clearances during steady
state operation. The cold clearances for the labyrinth
seal were set based on avoiding contact between the
shrouds and the bucket tips during transients.
Honeycomb seals are designed for contact between
the bucket tips and shrouds to occur during
transients, thus providing relatively tighter clearances
during steady-state operation.
Honeycomb seals are made of a high-temperature,
oxidation resistant alloy with 1/8 inch cell size and 5
mil foil thickness is brazed between the teeth on the
shrouds. “Cutter teeth” on the leading edge of the
shrouded stage 2 and 3 bucket tip rails will “cut” the
honeycomb material away when contact occurs
during transients. This produces steady-state running
clearances which are, on an absolute basis, no larger than the difference between the steady-state and the
transient clearances. The effective clearance is
actually tighter than the absolute clearance, since the
resulting groove in the honeycomb provides a tighter
labyrinth seal than could be obtained with solid
materials.
Installation of honeycomb shrouds requires
buckets with cutter teeth. As previously mentioned,
current production stage 2 and 3 buckets have cutter
teeth. Additionally, buckets with fewer than 48,000
hours of service can have cutter teeth applied in a
qualified service shop.
COMPRESSOR COMPONENTSThe first four stages of the MS9001B compressor
were completely redesigned for the MS9001E model.
Because new compressor casings and all new
compressor rotor and stator blades would be required
to upgrade the MS9001B compressor to the later
design compressors, this is usually not economically
feasible and not typically quoted as part of a turbine
uprate.Instead, the existing MS9001B compressor can be
re-bladed with the same design/length blades, with
special blade coatings or materials available for
certain applications. Until recently, a NiCad coating
was applied to the first 8 stages of the compressor.
NiCad coating helps prevent corrosion pitting on the
blades by combining a tough barrier coating of nickel
with a sacrificial cadmium layer. NiCad coating has
been replaced by GECC1. GECC1 provides the same
protection as NiCad without the use of cadmium.
Both GECC1 and NiCad possess outstanding
corrosion resistance in neutral and sea saltenvironments.
High Pressure Packing Seal (FS2V)
The seal between the compressor discharge casing
inner barrel and the compressor aft stub shaft is
called the High Pressure Packing (HPP). The HPP is
designed to regulate the flow of compressor discharge
air into the first forward wheel space. The HPP
8/20/2019 GE MS 900 Series
15/18
GER-3928A
15
clearance determines the amount of flow to the wheel
space. Ideally this flow is limited to the amount
required for first forward wheelspace cooling. With
the conventional labyrinth tooth/land seal packings on
the inner barrel, the minimum clearance that can be
tolerated is dictated by the expected rotor
displacements during transient conditions and by
wheelspace cooling requirements. If a rub does occur,the labyrinth teeth can be damaged and cause
excessive leakage through the packing. A 20 mil rub
is equivalent to a loss of approximately 1% in output.
Two different designs have been used to reduce
leakage through the HPP. New units built since
April, 1994 have shipped with a honeycomb seal on
the inner barrel (similar to the design used for stage 2
and 3 shrouds previously described). Retrofitting
honeycomb seals would involve removing the rotor,
and replacing the aft stub shaft with a new design
with cutter teeth. The inner barrel would also have to
be replaced. A new brush seal arrangement has been
developed that provides the same level of
performance improvement associated with
honeycomb seal and requires fewer modifications to
the unit. The HPP brush seal is shown in Figure 29.
Rub-tolerant brush seals are designed to withstand
rotor excursions and maintain clearances in this
critical area. Metallic brush material is used in place
of one of the labyrinth teeth on the inner barrel. With
brush seals at the high pressure packing, the unit will
be able to sustain initial performance levels over an
extended period of time because the inevitable rubwill not increase the clearance. In order to retrofit a
brush seal, the existing inner barrel must be removed
and replaced with an inner barrel of a brush seal. The
inner barrel with brush seal is designed for use with
the existing compressor aft stub shaft with high/low
lands. High pressure packing brush seals, which are
available for both the 9B and the 9E, provide 1.0%
increase in output and 0.5% improvement in heat rate
when replacing the original labyrinth design. The
high pressure packing brush seal provides 0.2%
improvement in both output and heat rate relative to
the honeycomb design.
No. 2 Bearing Brush Seals
The Frame 9E is a three bearing machine that
includes two air seals in the No. 2 bearing housing–
one on either side of the bearing. The brushes provide
a tighter seal than the original labyrinth seal. Since
any air that leaks past these seals into the bearing
housing does not perform any additional work in the
turbine, any reduction in this flow will result in an
increase in performance. This upgrade has been
tested in the field, but the performance benefit has not
yet been quantified. Brush seals for the No. 2 bearing
are illustrated in Figure 30.
HIGH-FLOW INLET GUIDEVANES (FT6B)
A widely used product of the MS7001F
development program is the GTD-450 reduced
camber, high-flow inlet guide vane shown in Figure
31. The new design, introduced in 1986, was quickly
applied across the entire GE heavy-duty product line
to enhance field unit performance. The reduced
camber, high-flow inlet guide vane is a flatter, thinner
inlet guide vane designed to increase air flow while
remaining directly interchangeable with the original
IGV. The reduced camber IGV, when open to 84°,can increase power up to 4.3% and decrease heat rate
by up to 0.7% (depending on the model of the gas
turbine) while improving corrosion, crack and fatigue
resistance. Opening the IGVs to 86° increases the
output an additional 0.4% at the expense of the heat
rate, which will increase by 0.2%.
The enhanced IGVs have higher reliability due to
the use of a special precipitation-hardened,
martensitic stainless steel, GTD-450, which is
improved over the type 403 previously used (Figure
32). Material developments include increased tensile
strength, high-cycle fatigue, corrosion-fatiguestrength and superior corrosion resistance due to
higher concentrations of chromium and molybdenum.
The modification kit includes new tight clearance,
self-lubricating IGV bushings. A new rack and ring
assembly, which controls guide vane positioning, can
be provided for improved reliability. GTD-450 IGVs
are available for the 9000IE and the 90001B.
PACKAGING OF MS9001
SERIES UPRATESEach of the advanced technology componentsdescribed can be installed in any of the existing
MS9001 units with little or no modification.
The major component design improvements are
outlined in Figure 33. While some of these
components provide performance benefits
individually (Figure 34), the most dramatic
performance benefits are obtained through increases
in firing temperature. Generally, increases in firing
8/20/2019 GE MS 900 Series
16/18
GER3928A
16
temperature require a series of component changes
based on the original configuration of the unit and the
desired firing temperature. Therefore, several
different packages have been designed for the
MS9001 to provide the maximum benefit to the
customer. There are four packages for the MS9001B
and two packages for the MS9001E. In this section
each of the packages will be discussed.
MS9001B Turbine Uprates (FT6X)
The MS9001B turbine uprate is based on
installing current production MS9001E components
into the MS9001B. This uprate package contains
four different options. The performance
improvements associated with each of these options
are given in Figures 35 and 36. The major design
improvements associated with the components
included in this uprate are outlined in Figure 33. In
addition to improving performance, themaintenance/inspection intervals can be increased.
Figure 8 contrasts the inspection intervals of the
MS9001B and MS9001E for some components.
Option 1 contains the advanced technology stage 1
buckets and nozzles and GTD-450 reduced camber
inlet guide vanes. This option maintains the firing
temperature at 1840°F/1004°C while increasing the
thermal efficiency, which decreases the exhaust
temperature. This uprate option provides an increase
in output of 6.4% at ISO conditions, with the IGVs
open to 86°.Option 2 raises the firing temperature to
1905°F/1040°C, which is the maximum firing
temperature that can be achieved while maintaining
the original exhaust temperature. In addition to the
components supplied for Option 1, this option
includes new stage 2 buckets and nozzles, new stage
1 shroud, TBC coated slot-cooled liners, Nimonic
transition pieces and the Extendor combustion
upgrade. The stage 2 buckets are advanced-
technology GTD-111 buckets without air-cooling.
Option 2 is feasible for combined-cycle applications
where a decrease in exhaust temperature wouldreduce the overall combined-cycle efficiency and an
increase in exhaust temperature might be limited by
the Heat Recovery Steam Generator (HRSG). It
should be emphasized that the performance benefits
given in Figure 34 are based on the IGVs opened to
86°, and assume that all of the options have been
installed.
Option 3 is designed to raise the exhaust
temperature to the limit by increasing the firing
temperature to 1965°F/1074°C. In addition to the
material provided for Options 1 and 2, stage 3
buckets, nozzles, shrouds and the turbine rotor 1/2
wheel spacer are also provided. Unlike Option 2, the
stage 2 bucket will be air cooled. This uprate option
provides a 18.2% increase in output at 86° IGV angle
and ISO conditions.
Option 4 raises the firing temperature to2020°F/1104°C. This option includes all of the
components in Option 3, as well as a new exhaust
frame and two 100 hp exhaust frame blowers to
accommodate the increase in exhaust temperature.
Increasing the firing temperature to this level can
increase the output by 24.1% at 86° IGV angle and
ISO conditions.
Prior to the sale of any of these options, an
engineering review of the turbine/generator
performance will be required to ensure that the load
equipment can accommodate the increase in output.This review may indicate that the load equipment
needs to be uprated. In many cases the generator can
be “uprated” by operating at a higher power factor.
A typical MS9001B performance study is illustrated
in Figure 37.
MS9001E Uprate to 2020°°F/1104°°C
Firing Temperature (FT6C)
This uprate package is designed for MS9001E
units with firing temperatures below 2020°F/1104°C.
Like the MS9001B turbine uprates, this package is based on installing the latest technology components
into earlier vintage machines. The material required
for the firing temperature increase is listed in Figure
34. An engineering review of the current turbine
configuration will be provided to determine the
material that will be required for the uprate. Figure
38 contrasts the combustion inspection intervals for
various combustion systems with and without
Extendor TM
.
The increase in output associated with the uprate
is also dependent upon the original configuration of
the unit. Figures 35 and 36 provide the performance
gains associated with each of the components as well
as the entire uprate package. Again, it is important
that the turbine/generator be evaluated to determine if
the current load equipment can withstand the increase
in output associated with this uprate.
MS9001E Uprate to 2055°°F/1124°°C
Firing Temperature (FT6Y)
8/20/2019 GE MS 900 Series
17/18
GER-3928A
17
This uprate package is designed for MS9001E
units with firing temperatures below 2055°F/1124°C.
This package will provide the advanced technology
components to increase the firing temperature of an
earlier vintage MS9001E to 2055°F/1124°C, the
highest firing temperature available on an MS9001E.
The material required for the firing temperature
increase is listed in Figure 34. The material requiredfor a given unit will vary depending on the current
turbine configuration. An engineering review can
define the material that will be required for the
uprate.
The increase in output associated with the uprate
is dependent upon the original configuration of the
unit. Figures 35 and 36 provide the performance
gains associated with each of the components as well
as the entire uprate package. Again, it is important
that the turbine/generator be evaluated to determine if
the current load equipment can withstand the increasein output associated with this uprate.
ABSOLUTE PERFORMANCE
GUARANTEESThe performance uprates discussed in this paper
are based on airflow or firing temperature increases
directly related to performance increases, expressed
as “percentage” or “delta” increases. Quantifying
turbine performance degradation is difficult due to
the lack of consistent and valid field data. In addition,
several variables exist; including site conditions andmaintenance characteristics, operation modes, etc.
which affect turbine performance and degradation
trends. Delta uprates, providing a percentage change,
are consistent with or without turbine degradation
factors. Absolute guarantees must factor in
degradation losses to calculate the final expected
performance level. Therefore, the absolute
performance guarantees offered usually appear
slightly different than delta percentage changes in
order to account for turbine degradation.
LIFE EXTENSIONOwners can also take advantage of technology
improvements by using state-of-the-art components to
replace older component designs during major and/or hot
gas path inspections instead of replacing in kind. The
advanced technology components yield an increased
service life when used in machines that fire at
temperatures lower than that for which the component
was designed.
EMISSIONSEmission levels are affected when the gas turbine
is uprated, and these levels must be accounted for in
planning. Emission control options reduce the
emission levels, and Figure 39 compares typical NOx
emission levels before and after uprates for many of
the options discussed. Individual site requirements
and specific emission levels can be provided with any
uprate study.
CONTROL SYSTEMS
UPGRADESThe MS9001 turbines are controlled by the
SPEEDTRONIC™ Mark I through Mark V
generation controls. Several control system
enhancements and upgrades are available for all
vintages of gas turbine control systems. More reliable
operation is offered by today’s superior controltechnology. Enhanced operating control can be
realized by units with older control systems. “Control
System Upgrades for Existing Gas Turbines in the
1990s” (GER-3659) details available control and
instrumentation upgrades available for the MS9001
series.
MS9001 Uprate Experience
The MS9001B is a scaled version of the
MS7001B and the MS9001E is a scaled version of
the MS7001E; therefore, the confidence level on theMS9001B/E uprate is very high based on a
successful history in MS7001B/E uprate experience.
GE has successfully uprated twelve sets of
complete MS7001B/EA uprate hardware on field
units. Figure 40 lists the MS7001 uprate experience
list to date. Additionally, dozens of upgrades and
uprates are being reviewed with customers
continually. Yet, many other customers have chosen
to install current design 7EA components as single
spare parts replacements just as components are
required.The first MS9001E to 2055°F/1124°C uprate was
successfully completed at ESB Ireland in 1990.
Because this was the first uprate of its kind, extensive
testing was completed to monitor compressor
performance and start-up characteristics. Upon
successful testing it was concluded that the 9E to
2055°F/1124°C uprate program would be offered.
To date the uprate at ESB is the only full unit firing
temperature uprate package that GE has completed,
8/20/2019 GE MS 900 Series
18/18
GER3928A
18
however dozens of customers have realized the
performance benefits associated with many of the
latest technology components on a individual basis.
INSTALLING INDIVIDUAL
MS9001E PARTS FOR
UPGRADE/MAINTENANCESome customers may prefer to order certain
components only as individual parts. For these
customers, GE can develop a staged uprate program
to meet their individual needs. Design technology
benefits, and material and maintenance improvements
allow upgrade components to be integrated on an
individual basis as an alternative to a complete uprate
package. As new technology parts are installed,
completion of the uprate can be scheduled and
controls modified to achieve the new design firing
temperature or other uprate objectives.
SUMMARYGE has an advanced technology uprate package
available to uprate all GE design MS9001 heavy-
duty gas turbines. These advanced uprate technology
packages provide significant savings derived from
reduced maintenance, improved efficiency, output,
reliability and life extension. Regulatory
requirements may necessitate the need for emission
controls due to changes in emission levels when
uprating the gas turbine, and modifications are
available to significantly reduce emissions. Today’s
technology and enhanced production components
allow customers to bring their aging turbines back to
better than new condition based upon these offerings.
REFERENCES1. Beltran, A.M., Pepe, J.J. and Schilke, P.W.,
“Advanced Gas Turbines Materials and
Coatings,” GER-3569, GE Industrial & Power
Systems, August 1994.2. Brandt, D.E. and Wesorick, R.R., “GE Gas
Turbine Design Philosophy,” GER-3434, GE
Industrial & Power Systems, August 1994.
3. Brooks, F.J., “GE Gas Turbine Performance
Characteristics,” GER-3567, GE Industrial &
Power Systems, August 1994.
4. Davis, L.B., “Dry Low NOx Combustion
Systems For Heavy-Duty Gas Turbines,” GER-
3568, GE Industrial & Power Systems, August
1994.
5. Dunne, P.R., “Uprate Options for the MS7001
Heavy-Duty Gas Turbine,” GER-3808, GE
Industrial and Power Systems, 1995.
6. Johnston, J.R., “Performance and Reliability
Improvements for Heavy-Duty Gas Turbines,”
GER-3571, GE Industrial & Power Systems,August 1994.
7. GEA-12526 (8/95), 12220.1 (1/94) MS9001E
Gas Turbines: Conversions, Modifications and
Uprates.
Top Related