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Presented by:
Daniel Sculley, Manager
Turbine, Generator & Piping
Systems Engineering
APP Site Visit
October 30 ± November 4, 2006
Turbine/Generator
Upgrades andMaintenance
Turbine/Generator
Upgrades andMaintenance
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Topics
Turbine Blading & Steam Path Upgrades
Turbine Stop / Control Valve Upgrades
Turbine Control System Modernization Generator Improvements
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Steam Path Improvements
More than 20 units in plan for upgrade
Efficiency gain ± Aerodynamic blade profiles
± Improved inter-stage sealing
± Reduction of sidewall secondary flow losses
Reduction in future O&M costs
± Extend time between overhauls ± Reduction of solid particle erosion damage
± Less coal burned
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Glen Lyn 6 Series 235MW (GE) HP/IP
Nine (9) Units (Subcritical, 1957 - 1961) Integral control valve chest girth weld creep
Purchased complete spare in 1990
Exchanged on other 8 units (1991 ± 2004)
New rotors ± replaced ³C´ grade materials
New nozzles, diaphragms (Rows 1,9,10,12)
Reassemble non-outage; 4-week reduction
Cost = $8 Million (US) first unit installed, approx.
Cost = $4 Million (US) subsequent units, approx.
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Glen Lyn 6 Series 235MW (GE) HP/IP
ResultsRestored CV chest with improved girth weld
Improved HP efficiency by 1.5% - 2.0%
2.5 MW and 35.28 kcal/kWh (140 Btu/kWh) gain
Erosion minimized, reduced repairs
Extended inspection intervals to 10-11 years
Re-inspections begun in 2001 confirm benefit
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1300 MW Series (Alstom) HP
Six (6) Units (Supercritical, 1973 ± 1989) Use of spare rotor/inner casing assembly
Replaced all stationary/rotating rows (28)
Reuse rotor and re-round inner casing Modified seal strips for steam swirl stability
Cost = $6 Million (US) per unit installed, approx.
Results
Blading Efficiency > 92.0%, increase of 4.7%20 MW and 28.5 kcal/kWh (113Btu/kWh)
Improved rotor stability against steam swirl
3 Units completed - - 1 with premature degradation
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600,800 MW Series (GE) HP/IP
Eight (8) Units (Supercritical, 1967 ± 1972)
To date, four have been converted
New nozzles, diaphragms, seals
Reblade spare rotor; reuse shells Cost = $6.5 Million (US) per unit installed, approx.
Results
82.8% - 86.3% HP section efficiency
11MW gained on 800MW Series
600 MW Series HP fell short of expectations by up to3.5% due to overstated recoverable losses by OEM.
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Effect of Advanced Design Steam Path
Effi i i f HP i
BS #
#BS#
D#
#5
74
7
7
4
4
i (Y )
E f f i
i ADSPigina Design
o ma ve ha
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Big Sandy Unit 1 HP-IP/SFLP
One (1) unit, W design (Subcritical, 1963)
HP turbine complete and IP/SFLP turbine rotor andinner casing ± install 2008
Inefficient original design Internal components subjected to erosion and
distortion
Creep damage evident
No spare blade rings or rotors
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Original Design Issues
EfficiencyTurn-around
Pressure Loss
Curtis Stage
Poor E iciency
Conventional Cylindrical Air oil
Poor E iciency
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Existing Maintenance Issues
Reliability
Large Blade Ring
Distortion, Rubbing,
Blade Leaning
L-0 Blade Fatigue Li e
Blade Failure
L-0 Shrunk-on Disc
SCC Potential
Large Dia. Inner Casing CrMo casting
Distortion, Rubbing
Stage 1 Blade Root Distortion
Stages 2-4 Blade Untwist
IP/SFLP Rotor
44 years Old
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New HP Section Design
Monoblock
No Bore Rotor
Separately supportedblade rings andbalancing ring
3-D Reaction Blades
ISB
ACC PackingActive Clearance Control
Integral Inner Casing
Rateau control stage
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New IP/LP Section Design
ACC PackingActive Clearance Control
Mono block no borerotor
No Shrink- it
Separately-SupportedBlade Rings
3-D Reaction Blades
ISBIntegral Inner Casing
25in ISB
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Big Sandy Unit 1 Expectations
Anticipated Results
± Improved reliability and design efficiency
± HP efficiency +4.1%
to 88.9%
± IP efficiency +3.1% to 94.6%
± Expect +18 MW at original design steam flow
± Includes replacement throttle/governor valves
± Installed cost $18Million (US), approx.
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LP Turbine Performance Retrofits
AEP experience driven by reliability issues
Stress Corrosion Cracking on blades, disks and LowCycle Fatigue on blade attachments
Flow limit for L-1 rotating blade causes curtailment LP turbine exhaust limit = 140 mm HgA (5.5 in HgA)
Frequently caused summer time curtailments
Solution = LP Turbine Upgrade
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LP Turbine Performance Retrofits
Four (4) BB73 W LP steam paths ³ruggedized´
Improved material properties to resist SCC and LCF
Aerodynamic improvements to blades and inlet / exhaust
flow guides Improved seal design to reduce leakage
Full load capable to 203 mm HgA (8 in HgA)backpressure
Improved performance: 3.4MW, 22.4 kcal/kWh (89Btu/kWh)
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Stop/Control Valve Upgrades
Material Damage ± Thermal fatigue, creep
Reliability
± Tight shutoff, leaks Maintenance
± Weld repair to valvebody, seats, bolt holes
Design Improvement ± Improve O&M
± Reduce pressure drop
1 3 0 0 M W r
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1300 MW Series SV/CV Upgrades
Original Design ± Pressure drop across
combined valves = 5.1%
± Limited steam flow at VWO+ 5% overpressure
± Significant solid particleerosion damage
± Expensive repairsperformed every 2-3 years
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1300 MW Series SV/CV Upgrades
New Design ± Separate stop and control
valve chambers
± Actual pressure dropacross valves = 2.08%
± Achieved 32 MW increasedgeneration capabilitywithout changing boiler conditions
± Updating valve actuators todigital controls
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Turbine Control System Upgrades
Converting original MH and analog EH controls to digital
Integrated into plant Distributed Control System
Reuse or modify hydraulic systems
Use fire resistant fluids Expectations
± Enhanced control
± Fewer unit trips
± Faster startup/ramp rates
± Online testing of turbine valves and protective devices
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Turbine Control System Upgrades
Results
Smooth, rapid rollups to synchronous speed
CV position and load ramping optimized by stress
probeCV stroke ramped according to test throttle pressure
Improved reliability during protective device checks
Lower peak speeds reached during turbine trip
Reduction in boiler tube leaks due to ³soft´ trips
All contribute to improved reliability and performance
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Generator Improvements
Inspection Intervals (typical)
± Field in-place ( 5 years)
± Field removed (10 years) ± Perform routine cleaning, testing, repairs
Goal: Achieve high reliability through designlife of insulation systems
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Generator Rewinds
Rewinds Offer Opportunity for Improvement ± Required for reliability and maintenance purposes
± Efficiency improvements are small added benefit
Stator Windings ± Asphalt stator bar insulation replaced with modern epoxy-mica
insulation
± Potential for increased copper cross-section in original slots
± Improved cooling gas or water flows reduce operatingtemperature and extend design life
Stator Cores ± Inspect and test for looseness, hot spots, resonance
± Several cores replaced (full, partial)
± Reference papers available in Breakout Session
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Generator Rewinds
Fields
± Replace retaining rings with 18Mn 18Cr material
± Improve end turn blocking design and materials
± Restore/replace copper and replace all insulation ± Optimize cooling gas flow
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Summary
AEP has been retrofitting turbine generator equipment withefficiency improvements for more than 15 years.
Experience with OEM and non-OEM solutions.
Economic benefit drives the HP and IP turbine retrofits.
Must consider design improvement vs. restoration improvement. Turbine valve design could provide upgrade potential.
Turbine control integration can produce thermal benefits.
Reliability benefit drives the LP turbine and generator retrofits(typically). Some small efficiency improvements are possible.
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Breakout Session
Two Sessions on Tuesday Afternoon
Expert Attendees
± Steve Molick ± Turbine Services Manager ± Jim Michalec ± Staff Engineer, Generators
± Alex Manukian ± Sr. Engineer, Turbines
± Jim Cable ± Sr. Engineer, Turbines, Controls
± Dan Sculley ± TG&PSE Manager
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Questions