Steam Deflectors
(Spill Strips)
Bucket Tip
Leakage
Stationary Diaphragm
Design
Steam Path
Stationary Blade
Rotating Blade
Packing Ring
Rotor Wheel
Packing Leakage
Turbine Rotor
Typical Impulse Steam Path (i.e. GE, Hitachi, Toshiba, etc.)
Vortex Shedder Shape Applied to the
Spill Strip only on the 1st up stream
tooth
Conventional Spill Strip
Reduced
Bucket Tip
Leakage
form the
Vortex
Shedder
Stationary Diaphragm
Design
Steam Path
Stationary Blade
Rotating Blade
Guardian
Packing Ring
Rotor Wheel
Turbine Rotor
Reduced Packing
Leakage
Typical Impulse Steam Path With TPL’s Advanced Seals
Typical Reaction Steam Path (i.e. Westinghouse, ABB, Mitsubishi, Kraftwork Union)
uses inserted Seal Strips
Stationary Cylinder
Steam
Flow
Rotor
Nozzle Profile
15%
Nozzle Secondary Loss
15%
Root Leakage
4%
Shaft Packing Leakage
7%
Blade Secondary Loss
15%
Tip Leakage
22%
Rotation
3%
Carryover
4%
Blade Profile
15%
Typical Efficiency Losses per Stage for General Electric Turbines
What Can Cause Rub’s
• 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
What Occurs During Rubs
For 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.
Turbine Rotor
•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
Spring Tension
Conventional Seal
In a Rubbing Condition
Steam
Flow
Rotating Shaft
Guardian Seals
Theory Behind Design
•Prevents damage to conventional seal in
any rub situation
•No stationary fit modifications required
TURBINE
ROTOR
•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
Spring Tension
•Extends Seal Efficiency Life
•Extends unit Heat Rate between
Overhauls
Guardian Seal
•Improves unit reliability
Steam
Flow
•Limits seal degradation
Rotating Shaft
Guardian Seals
Practical Application
•Lighter coil springs lessen radial forces only during
startup
TURBINE
ROTOR
•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
Spring Tension
Guardian Seal
In a Rub Condition
•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.
Steam
Flow
Rotating Shaft
•The Guardian Seal Can Not remain in a Retracted
position. Thus eliminates this potential for major
efficiency losses due to this situation
Laboratory Hard Rub
Test
• Standard Tooth
• Note the discoloration cased
by hard rubbing which
generated intense heat at
the tooth tips
• Guardian with Standard
Teeth
• 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
Test Rotor
Before 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
After Partial Cleaning
•
•
•
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
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
N3 Grv 5
HP-IP
• This gland is adjacent to the #2 Bearing in the previous slide
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
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.
Bottom
Segment
Bottom center segment view, Note minimal damage to Guardian Post and
conventional teeth
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.
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.
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 nonsulferized 12Cr material
•Uses OEM design Radial Clearances
Typical Reaction Steam Path using inserted Seal
Strips
Stationary Cylinder
Steam
Flow
Only one tooth
on the steam
admission side
gets the Vortex
Shedder
Rotor
Radial Seal Height
must be at least 0.200
inches in order to
effectively install the
Vortex Shedder