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Maintenance of V94 series of gas turbines, Power Gen Russia, Moscow, 2010
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Maintenance of V94 series of gas turbines, Power Gen Russia, Moscow, 2010

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Maintenance of V94 series of gas turbines, Power Gen Russia, Moscow, 2010 Maintenance of V94 series of gas turbines, Power Gen Russia, Moscow, 2010 Presentation Transcript

  • Russia Power 2010 Turbo Services Maintenance of V94.0/V94.2 series of gas turbines Dr Shaun West and Sjef Mattheij MSc, Sulzer Turbo Services | slide 1
  • Contents Turbo Services  Background  Component life analysis  Corrosion and oxidation  Material degradation  Creep  Fretting  Fatigue  Rotor life management  The manufacture of gas turbine blades  Summary | slide 2
  • Sulzer Turbo Services’ experience - over 15 years of know how developed Turbo Services V94.2 series Total V-series Combustion component repairs (burners, star plates, mixing chambers, hot gas casings) 50 sets of parts 76 sets of parts Blade and vane repairs 672 sets of parts 1485 sets of parts 16 inspections 28 inspections 35 projects 56 projects 37 sets of parts 93 sets of parts 10 units 11 units Field services (mechanical, controls, fact finding, minor and major inspections) Rotor services (de-stacking, inspection, restacking, balancing, NDT, life assessment) New and replacement parts (consumables, combustion section, turbine section) Long-term service agreements | slide 3
  • 15 years of component repair experience - development of proprietary know how Turbo Services  Repair experience starting in the 1990s  Compressor section  Burners  Flame tubes  Hot gas casings  Power turbine  Build up of proprietary know how  Based on earlier and later V-series units  Based on repairs of gas turbines of other OEMs  Based on operator feedback | slide 4
  • Repair of blades - metallurgical understanding key to repairs  Known operational issues Turbo Services  Repair processes  IN 738/Sicoat 2231  Striping of coating  Cracking leading edges (row 1)  Heat treatment  IGA  NDT  Welding  Overlay repair by slurry-brazing  Blending  Heat treatment  Coating (where applicable)  Sulzer inspection techniques  X-ray  Boroscope inspections  Thermographic analyses | slide 5
  • Repair of vanes - metallurgical understanding key to repairs  Known operational issues Turbo Services  Repair processes  Nitration of IN 939  Striping of coating  Fatigue cracking  Heat treatment  Distortion  NDT  Welding  Overlay repair by slurry-brazing  Blending  Heat treatment  Coating (where applicable)  Sulzer inspection techniques    X-ray inspection Visual inspection of internals Dimensional inspection: tooling | slide 6
  • Repair of combustion parts - metallurgical understanding key to repairs  Known operational issues Turbo Services  Repair processes  Nitration of IN617  Assessment of damage  Fatigue cracking  Restoration of shape  Distortion/overheating  Solution heat treatment  Removal of damaged areas  Sulzer inspection techniques  Visual inspection  Repair and replacement of damaged parts  Dimensional inspection: tooling  Stress relieve heat treatment  Metallurgical inspections  Thermal Barrier Coating application  Hard facing and assembly of auxiliaries | slide 7
  • 2001 the first major overhaul - planning and know how key to success Turbo Services  Scope  Site works (fact finders, QA, site management, technical advisors…)  Rotor removal, de-stack, re-stack and balancing  All blades and vanes repaired  Replacement of consumables  Challenges  Unit has been build within existing power plant  Unit was an early .0 version | slide 8
  • Inspection challenges - rotor line out is a critical issue Turbo Services  Correct procedures are required  Attention to x, y and z direction (more than with annular combustors  Correct tolerances on repair mixing chambers and HGC Know how is key to success | slide 9
  • 10 years experience with replacement parts - new parts based on repair experiences Turbo Services  Special tooling critical for the component repair  Experience based on repair and manufacture of many different silo combustion systems  Weld procedures important to maintain dimensional integrity | slide 10
  • Contents Turbo Services  Background  Component life analysis  Corrosion and oxidation  Material degradation  Creep  Fretting  Fatigue  Rotor life management  The manufacture of gas turbine blades  Summary | slide 11
  • Corrosion and oxidation - three different damage mechanisms Cr 2 O 3 Protective layer Turbo Services TBC Al 2 O 3 Inter-diffusion Thermo mechanical fatigue Attack Type II Hot Corrosion 500 600 Type II Type Hot Corrosion 700 800 Temperature (°C) 900 Oxidation 1000 1100 | slide 12
  • Material degradation - material strength reduces over time Material Degradation  Gamma prime strengthens super Dissolution and growth of γ’- precipitates alloys Turbo Services  Heat treatments can restore the Sulzer Turbo Services structure  Time at high temperature causes Gamma Prime Size / Temperature distribution rounding of the crystals LE CC CV TE TIP MIDDLE ROOT γ’ precipitate size changes with time & temperature | slide 11 | slide 13
  • Creep - Creep damage cannot be recovered Turbo Services  Slow deformation at constant stress level at high temperatures ( T > 0.4Tm )  Material properties are important, like grain size and volume of γ’precipitates  Creep is a thermally activated  Strain rate increase with stress and temperature  Life time reduces with increase in stress and temperature | slide 14
  • Fretting - damage minimization is key Turbo Services  Material removal as a result of sliding wear  Contact between to surfaces  Vibration  Transition pieces  Seals  Mounting brackets  Wear resistant coatings or linings are usually efficient (W-Cr carbides, Stellites) | slide 15
  • Cyclic fatigue - regular visual inspections are important  High cycle fatigue Turbo Services  Low cycle fatigue Large number of cycles until failure (>100,000 cycles) Low number of cycles until failure (<100,000 cycles) Crack initiation can take a long time Crack initiation period relatively short Required stress amplitude is relatively low Stress amplitude is high Vibration can be caused by: Tip rubbing Resonance Aerodynamic instabilities ∆σ [MPa] LCF Fatigue limit HCF 100 1000 10000 100000 1000000 10000000 Number of cycles [#] | slide 16
  • High cycle fatigue - catastrophic compressor failure Turbo Services  Excitation caused by: single VIGV closing, blade rub etc Mode 1 Mode 2 Mode 3 Mode 4 Mode 5 Mode 6 | slide 17
  • Low cycle fatigue - start/stop related Turbo Services IN939 vanes suffering LCF following imbrittlement of the base material | slide 18
  • Contents Turbo Services  Background  Component life analysis  Corrosion and oxidation  Material degradation  Creep  Fretting  Fatigue  Rotor life management  The manufacture of gas turbine blades  Summary | slide 19
  • Rotor life management - extending operation safely Turbo Services  Rotor material can become brittle  Replica and phased array NDT are two assessment tools  Rotor operational history important  Rotors can suffer low cycle fatigue  Finite element modeling provides stress data  Some damage can be repaired/replaced Example of FEA on rotor disk | slide 20
  • Contents Turbo Services  Background  Component life analysis  Corrosion and oxidation  Material degradation  Creep  Fretting  Fatigue  Rotor life management  The manufacture of gas turbine blades  Summary | slide 21
  • The manufacture of gas turbine blades - over 35 years of experience Turbo Services  Reverse engineering started in 1980s  Supporting Russian gas pumping units  Many different designs for different units  Key processes  Measurements (parts and fit with adjacent parts)  Understanding the design intent  3D-CAD drawings  Casting  Machining | slide 22
  • Contents Turbo Services  Background  Component life analysis  Corrosion and oxidation  Material degradation  Creep  Fretting  Fatigue  Rotor life management  The manufacture of gas turbine blades  Summary | slide 23
  • Summary - driving towards improved performance Turbo Services Condition based maintenance supported by Sulzer can:  Extend operational life  Have a positive impact on total maintenance costs  Helps to allow informed decisions concerning ‘repair’ or ‘replace’  Provide the necessary information on critical components to manage component life, turbine life and inspection intervals. C&I sites services   Trouble shooting / hot line / remote condition monitoring  Compressor   Mechanical site services Planned and unplanned maintenance Parts Blades and vanes Combustion system Repairs LTSAs Rotor Component     | slide 24
  • Turbo Services | slide 25