Guardian

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Guardian Vortex Shedder Sealing System
Presentation
2
Advanced Sealing Technology For Steam Path
Efficiency Improvement Above OEM Design
3
Bucket Tip Leakage
Steam Deflectors (Spill Strips)
Stationary Diaphragm
Design Steam Path
Rotating Blade
Stationary Blade
Packing Ring
Rotor Wheel
Packing Leakage
Turbine Rotor
Typical Impulse Steam Path (i.e. GE, Hitachi,
Toshiba, etc.)
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Reduced Bucket Tip Leakage form the Vortex Shedder
Conventional Spill Strip
Vortex Shedder Shape Applied to the Spill Strip
only on the 1st up stream tooth
Stationary Diaphragm
Design Steam Path
Rotating Blade
Stationary Blade
Guardian Packing Ring
Rotor Wheel
Reduced Packing Leakage
Turbine Rotor
Typical Impulse Steam Path With TPLs Advanced
Seals
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Typical Reaction Steam Path (i.e. Westinghouse,
ABB, Mitsubishi, Kraftwork Union) uses inserted
Seal Strips
Stationary Cylinder
Steam Flow
Rotor
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Typical Efficiency Losses per Stage for General
Electric Turbines
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What Can Cause Rubs

• Misalignment, Alignment is Critical for all
  current seal Designs
• Balancing
• Thermal Distortion
• Harmonics
• Bearing Oil Whip
• Steam Whirl
• Generator Transients
• Incorrect Operation of the Boiler, Condenser,
  Generator, or Extractions
• Improper Starting and Loading Procedures for the
  Turbine Generator

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What Occurs During RubsFor Other then Guardian
Designed Seals

• Practical Application Concerns
• If a rub does occur there is a permanent loss of
  seal efficiency
• Springs do afford very little give or release if
  a rub conditions does happen
• Conventional tooth material has a relative high
  coefficient of friction.
• A rub can result in a hot spot which could lead
  to rotor bluing, scoring, or cutting. Worst case
  a bowed rotor.
• Hard and prolonged contact of the seal in a rub
  can result in a heat effected zone on the rotor
  increasing the possibility of a hydrogen
  embrittled area.
• Conventional tooth material mushrooms increasing
  the discharge area of the seal. This adds to a
  greater efficiency loss

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Guardian Packing
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Guardian Seals

• Theory Behind Design
• Prevents damage to conventional seal in any rub
  situation
• No stationary fit modifications required
• Works in any OEM designed turbine
• Will not cause bowed rotors
• Works in any Labyrinth Seal Ring
• Location or Application
• Works in any steam condition
• Works in any Pressure condition
• Extends Seal Efficiency Life
• Extends unit Heat Rate between
• Overhauls
• Improves unit reliability

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Guardian Seals

• Practical Application
• Lighter coil springs lessen radial forces only
  during startup
• The Guardian Post contacts the rotor first and
  prevents damage to the conventional teeth
• When rubs do occur with the Guardian they do not
  grow in intensity as with conventional materials
  or Brush Seals
• Conventional teeth still maintain factory radial
  Clearance during and after the rub occurs
• Guardian Post Material with its low coefficient
  of friction and long wearing characteristics
  prevents damage to the rotor body even during
  extreme rub conditions.
• Rubs during startup are proven not to cause rotor
  instability and/or higher bearing vibration
• Long term rubs due to misalignment have been
  proven not to cause any adverse effects in
  turbine operations.
• The Guardian Seal Can Not remain in a Retracted
  position. Thus eliminates this potential for
  major efficiency losses due to this situation

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Laboratory Hard Rub Test

• Standard Tooth

• Guardian with Standard Teeth

• Note the discoloration cased by hard rubbing
  which generated intense heat at the tooth tips

• Note only light contact because of the Guardian
  Seal Protection

Test Procedure Rotor Spinning at 3600 RPM, Seal
pushed downward against the rotor with 5,000 lbs.
of force for 40 minutes
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Test Rotor
Before Cleaning
After Partial Cleaning

• Guardian transferred a protective layer of
  Proprietary Material to the rotor.
• Proprietary Material rubbing on Proprietary
  Material has an extremely low coefficient of
  friction.
• Low coefficient of friction means very little
  heat generated by contact

• No Scoring or Grooving on rotor where the
  Guardian seal contacted the rotor.
• No heat effected zone where the Guardian Seal
  contacted the rotor.
• No change in rotor hardness where the Guardian
  seal contacted the rotor

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BRG 2 HP-IP
Turbine ran without oil, there was 1/8 of
babbit prior to accident. The rotor dropped
straight down and ran on the seals
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N3 Grv 5
HP-IP

• This gland is adjacent to the 2 Bearing in the
  previous slide

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N3 Grv5
N3 Grv6
HP-IP
Note Oil Deflector damage to rotor, No
damage where the Guardian Posts made contact to
rotor, it only polished the rotor. Even the
conventional teeth did not cause any damage
because of the protection provided by the
Guardian Posts
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Guardian Post
Conventional Teeth
N3 Grv 6 HP-IP
This is the bottom center segment from N3 Grv 6,
Note the minor damage to the Guardian Post and
conventional teeth. The packing ended up
supporting the weight of the rotor during the
accident.
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Bottom Segment
Bottom center segment view, Note minimal damage
to Guardian Post and conventional teeth
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N3 Grv 6 HP-IP
Opposite end view of the bottom center segment
NOTE Where all conventional packing rings were
installed in the unit, the rotor required
machining to remove heat effected zones created
from the sever rubs at these locations. No rotor
machining required where Guardian Rings were
installed.
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Conventional Spill Strips
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• Design Applications
• Seals by providing pressure drops using relative
  tight radial clearances (same principle as a
  nozzle)
• Stationary
• Typically Material selection based on Stage
  operating temperatures
• Spring backed NOT Spring loaded. This design
  allows for ease of installation only.

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Vortex Shedder
Efficiency Improver
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• Design Applications
• Reduces axial flow or leakage in a CFD modeling
  by 5.7 when compared to a conventional straight
  shape.
• This savings translates into 1.5-2.2 turbine
  steam path efficiency improvement above design
• The reduction in flow is accomplished by
  creating vortices at the tip of the seal. These
  vortices act as a pressure barrier thus reducing
  the pressure drop across the seal.
• Lower flow means higher efficiency.
• Lower flow also means less wear.
• All tip seals are manufactured from a
  non-sulferized 12Cr material
• Uses OEM design Radial Clearances

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Typical Reaction Steam Path using inserted Seal
Strips
Radial Seal Height must be at least 0.200 inches
in order to effectively install the Vortex Shedder
Stationary Cylinder
Only one tooth on the steam admission side gets
the Vortex Shedder
Steam Flow
Rotor