4 Conventional Spill Strip Reduced Bucket Tip Leakage form the Vortex ShedderVortex Shedder Shape Applied to the Spill Strip only on the 1st up stream toothStationary DiaphragmDesign Steam PathStationary BladeRotating BladeGuardian Packing RingRotor WheelReduced Packing LeakageTurbine RotorTypical Impulse Steam Path With TPL’s Advanced Seals
6 Typical Efficiency Losses per Stage for General Electric Turbines
7 What Can Cause Rub’sMisalignment, Alignment is Critical for all current seal DesignsBalancingThermal DistortionHarmonicsBearing Oil WhipSteam WhirlGenerator TransientsIncorrect Operation of the Boiler, Condenser, Generator, or ExtractionsImproper Starting and Loading Procedures for the Turbine Generator
8 What Occurs During Rubs For Other then Guardian Designed Seals Practical Application ConcernsIf a rub does occur there is a permanent loss of seal efficiencySprings do afford very little give or release if a rub conditions does happenConventional 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
10 Guardian Seals Theory Behind Design Prevents damage to conventional seal in any rub situationNo stationary fit modifications requiredWorks in any OEM designed turbineWill not cause bowed rotorsWorks in any Labyrinth Seal RingLocation or ApplicationWorks in any steam conditionWorks in any Pressure conditionExtends Seal Efficiency LifeExtends unit Heat Rate betweenOverhaulsImproves unit reliabilityLimits seal degradation
11 Guardian Seals Practical Application Lighter coil springs lessen radial forces only during startupThe Guardian Post contacts the rotor first and prevents damage to the conventional teethWhen rubs do occur with the Guardian they do not grow in intensity as with conventional materials or Brush SealsConventional teeth still maintain factory radial Clearance during and after the rub occursGuardian 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 vibrationLong 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
12 Laboratory Hard Rub Test Standard ToothGuardian with Standard TeethNote the discoloration cased by hard rubbing which generated intense heat at the tooth tipsNote only light contact because of the Guardian Seal ProtectionTest Procedure : Rotor Spinning at 3600 RPM, Seal pushed downward against the rotor with 5,000 lbs. of force for 40 minutes
13 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 contactNo 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
14 BRG # 2 HP-IPTurbine ran without oil, there was ≈ 1/8” of babbit prior to accident. The rotor dropped straight down and ran on the seals
15 This gland is adjacent to the #2 Bearing in the previous slide N3 Grv 5HP-IPThis gland is adjacent to the #2 Bearing in the previous slide
16 N3 Grv5N3 Grv6HP-IPNote 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
17 Guardian Post Conventional Teeth N3 Grv 6 HP-IPThis 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.
18 Bottom SegmentBottom center segment view, Note minimal damage to Guardian Post and conventional teeth
19 Opposite end view of the bottom center segment N3 Grv 6 HP-IPOpposite end view of the bottom center segmentNOTE: 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.
21 Design ApplicationsSeals by providing pressure drops using relative tight radial clearances (same principle as a nozzle)StationaryTypically Material selection based on Stage operating temperaturesSpring backed NOT Spring loaded. This design allows for ease of installation only.
23 Design ApplicationsReduces axial flow or leakage in a CFD modeling by 5.7% when compared to a conventional straight shape.This savings translates into % turbine steam path efficiency improvement above designThe 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 materialUses OEM design Radial Clearances
24 Typical Reaction Steam Path using inserted Seal Strips Radial Seal Height must be at least inches in order to effectively install the Vortex ShedderStationary CylinderOnly one tooth on the steam admission side gets the Vortex ShedderSteamFlowRotor