turbine case carbon seals bearing housing/pedestal bearing

Turbine CaseCarbon Seals

Bearing Housing/Pedestal

Bearing



Bearing

230 degrees f.230 degrees f.

Temperature



Bearing


Temperature

Steam



Bearing


Temperature

Steam Seal FailureSeal Failure

Condensate Magnet



Bearing

Steam moves out of the case, down the shaft and past the carbon seals to atmosphere.

Steam Path



Bearing

Some steam dissipates into the atmosphere. In some instances (such as in cold climates), this could cause a visibility hazard.



Bearing

It could also cause a slipping hazard as condensate collects on the ground, or can cause severe burns if contacted near the exhaust path.



Bearing

Lost steam is also money thrown into the wind.

$$$$$$$$$$

$$$$$$$$$$



Bearing

Yet another consideration – if water enters your bearing housing, the integrity of your oil (lubrication system) will be compromised.



Bearing

This could lead to bearing failure and ultimately, equipment failure.



Bearing

When shaft seals fail, your only barrier against oil contamination are your bearing case seals.

Condensate Magnet



Bearing

These seals can be standard OEM “H” seals, or “upgrades” such as modified “H” seals (Disrupter Seals) or aftermarket Barrier Seals.

Condensate Magnet

Solutions

Try to reduce or eliminate steam leakage at the source.

Solutions

Protect your oil from contamination.

The standard shaft seals on most small steam turbines are carbon rings.

Carbon Seals

If installed correctly, they provide a good seal. However they do deteriorate rapidly.

Carbon Seals

Effective Clearance Over Time

Carbon RingsAdvantagesAdvantagesInexpensiveInexpensiveEasy to installEasy to installPerform well when Perform well when properly sized and properly sized and installedinstalledLightweightLightweight

DisadvantagesDisadvantagesEasily cracked/ Easily cracked/

chippedchippedIf not properly If not properly

sized, can either sized, can either seize on shaft or seize on shaft or leak too muchleak too much

Short life, resulting Short life, resulting in high leakage in high leakage after short timeafter short time

Mechanical Seals

AdvantagesAdvantagesBest sealing performanceBest sealing performanceLonger life than standard Longer life than standard

carbon sealscarbon seals

DisadvantagesDisadvantagesExpensive initial investmentExpensive initial investmentDifficult to install, requires Difficult to install, requires

entire rotor to be removed entire rotor to be removed for installation/ maintenancefor installation/ maintenance

Can require permanent case Can require permanent case modificationsmodifications

Finite life-span before a Finite life-span before a costly overhaul is required.costly overhaul is required.

Mechanical Seals

Brush Seals

Brush SealsAdvantages

Moderately pricedModerately pricedMore durable than carbon More durable than carbon

sealssealsExtremely long lifeExtremely long life

Disadvantages Must be installed in shopMust be installed in shop Not stocked for all size Not stocked for all size

turbinesturbines Relatively new technology Relatively new technology

for steam applicationsfor steam applications Heavy “floating” seals can Heavy “floating” seals can

gravitate downward on gravitate downward on turbines that cycle, thus turbines that cycle, thus decreasing efficiencydecreasing efficiency

Brush Seals

Utility Turbines Utility Turbines Mechanical Drive TurbinesMechanical Drive TurbinesGas Turbines – Aircraft & IndustrialGas Turbines – Aircraft & IndustrialSingle Stage TurbinesSingle Stage Turbines

Elliott – All YR sizesElliott – All YR sizesDresser RandDresser RandGeneral ElectricGeneral ElectricWestinghouseWestinghouse

Current Applications

Brush SealsThe bristles, which run at "zero clearance", are oriented at an angle to the turbine rotor. The angle is in the direction of rotor rotation.

Benefits A typical brush seal is roughly comparable to a labyrinth tooth at a radial clearance of 0.005". Compare this value of the 0.015"to 0.025" design radial clearance often found on the stage packing of many units, one can see where brush seals could create substantial efficiency gains and reduced leakage.

Brush Pack

RotationShaft

Brush Pack

Holder

FenceFlow

Brushes are a Haynes 25 material

Holder is SS

The typical brush seal design consists of a pack of fine wire bristle material sandwichedbetween two plates. The two plates (or washers as they are commonly called) and thebrush pack are then joined together.

Little or no case modifications beyond original design specifications.

Lower sustained leakage than carbon rings.

Indefinite life span eliminating periodic replacement.

Brush Seals

Brush SealsInstallation Considerations

Sealing faces and ID Sealing faces and ID of carbon box areof carbon box aremachined to assuremachined to assurea good seal fit.a good seal fit.

Sealing faces and ID Sealing faces and ID of carbon box areof carbon box aremachined to assuremachined to assurea good seal fit.a good seal fit.

29Compressor & Turbine Services. LLC

Internal Alignment is ImportantInternal Alignment is ImportantInternal Alignment is ImportantInternal Alignment is Important


On Fixed (non-floating) Brush SealsOn Fixed (non-floating) Brush Seals

Suggested Shaft Coatings – Suggested Shaft Coatings –

None – Base MetalNone – Base Metal

Chromium CarbideChromium Carbide

Tungsten CarbideTungsten Carbide (preferred) (preferred)


Leakage Data From SST Test

Test comparing brush seals with cold (new) carbon seals

Brush seals installed with “zero” clearance

Carbon seals installed with 2.5 mil radial clearance

Carbon seals exhibit equivalent clearance of 4.3 mils

B = Brush Seal C = Carbon Seal

33

Effective Clearance over Time


Brush Seals vs. Carbon Rings

0

1

2

3

4

5

6

7

8

9

10

Start-Up One Month Six Months

Carbons

Brush Seals

Effective Clearance over TimeEffective Clearance over Time

Carbon seals will degrade almost immediately. Brush seal performance will always stay the same.


Brush Seals for Steam TurbinesBrush Seals for Steam Turbines May be used as a May be used as a replacementreplacement for for Carbon RingsCarbon RingsOrOr May be used May be used in conjunctionin conjunction with with Carbon Rings Carbon Rings

Application: Brush Seals to Replace Application: Brush Seals to Replace Carbon RingsCarbon Rings

Non Floating SealsNon Floating Seals

COST:COST:

Around $10kAround $10k

Per SSTPer SST

COST:COST:

Around $10kAround $10k

Per SSTPer SST39Compressor & Turbine Services. LLC


More Risky Than Brush/Carbon Combination Since Brush Seals DO

NOT Have a History for this Application. Only recommended for

turbines that are in continuous service.

(floating seals)

More Risky Than Brush/Carbon Combination Since Brush Seals DO

NOT Have a History for this Application. Only recommended for

turbines that are in continuous service.

(floating seals)


Application Requirements:Application Requirements:Brush Seals as Brush Seals as ReplacementReplacement for carbon for carbon

ringsrings

Minimum radial space Minimum radial space between shaft and packing between shaft and packing box ID of 1.0 inch typicallybox ID of 1.0 inch typically

Maximum pressure drop Maximum pressure drop across one seal is 150 psidacross one seal is 150 psid

Packing box must be Packing box must be reasonably aligned with reasonably aligned with bearingsbearings

Best used on turbines that are Best used on turbines that are in continuous operationin continuous operation

Drain

Brush Seals

41

Anti-rotation pinAnti-rotation pin

Split lineSplit lineBrushesBrushes

Sealing faceSealing face



Non Floating SealsNon Floating Seals

Elliott BYRHHElliott BYRHH


Flow

Drain PipeDrain Pipe

No.1No.1

No.2No.2

No.3No.3



Estimated around 100 turbines in operation with Brush Seals in this configuration.

No case modifications beyond original design No case modifications beyond original design specifications.specifications.

Lower sustained leakage than stand-alone carbon Lower sustained leakage than stand-alone carbon rings. rings.

Indefinite life span eliminating periodic Indefinite life span eliminating periodic replacement.replacement.

Protects carbon rings from contaminationProtects carbon rings from contamination

Reduces pressure on carbon ringsReduces pressure on carbon rings

Brush Seals/Carbon Rings - A Brush Seals/Carbon Rings - A

Winning CombinationWinning Combination


Leakage Data From SST Test

Test comparing brush seals with cold (new) carbon seals

Brush seals installed with “zero” clearance

Brush seals exhibit equivalent clearance of 3.4 mils radial

Carbon seals installed with 2.5 mil radial clearance

Carbon seals exhibit equivalent clearance of 4.3 mils

B = Brush Seal C = Carbon Seal

48

Solid Ring Solid Ring DesignDesign

Solid Ring Solid Ring DesignDesign

COST:

Around $ 3k – 6k

COST:

Around $ 3k – 6k


Brush SealsInstallation Considerations

Single Stage Turbine Brush Seal Benefits - Single Stage Turbine Brush Seal Benefits -

When used with carbon ringsWhen used with carbon rings

Brush Seal used to protect carbon rings

Carbon rings

Protects carbons 1) by reducing steam pressure.

2) Reducing particulate contamination.

One Brush Seal ring required upstream of carbons on both ends


Single Stage Turbine Brush Seal Benefits - Single Stage Turbine Brush Seal Benefits -

When used with carbon ringsWhen used with carbon rings

Brush Seal used to protect carbon rings

Carbon rings

Protects carbons 1) by reducing steam pressure.

2) Reducing particulate contamination.

One Brush Seal ring required

before the bleed-off.



Standard Brush Seal CTS Brush Seal

No case modifications beyond original design specifications.

Lower sustained leakage than stand-alone carbon rings.

Increased run-time.

Protects carbon rings from contamination

Reduces pressure on carbon rings

Single Stage Turbine Brush Seal BenefitsSingle Stage Turbine Brush Seal Benefits

To complement carbon ringsTo complement carbon rings


The Result is

Reduced

Maintenance

Costs

The Result is

Reduced

Maintenance

Costs55Compressor & Turbine Services. LLC

Our Sealing SystemsOur Sealing Systems

Brush SealsBrush Seals

•Designed & Manufactured at our facility•Light weight “floating” seal•Available for Elliott “YR” turbines (and many others)•Custom applications

Early non floating Brush Seal

Typical Carbon Ring

Steel Cased Brush Seal

CTS Brush Seal

Carbon

Brush Pack

CTS Brush Seals are lighter than traditional Brush Seals. In addition you have the benefits of two carbon rings and one Brush in each turbine slot. Eliminates the problems caused by heavier Brush Seals on turbines that cycle.

Disrupter SealsDisrupter Seals

•Designed & Manufactured at our facility•Superior design to reduce moisture in bearing housing•Cost effective

Support American owned small businesses!Support American owned small businesses!


Bearing

CTS “Disrupter” Seals deflect moisture away from the bearing housing by disrupting the steam that moves down the shaft.

Steam

Steam

turbine case carbon seals bearing housing/pedestal bearing

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