Labyrinth seal into two halves

Labyrinth Seal

Labyrinth Seal

•Labyrinth seals

Labyrinth seal consist of a series of circumferential strips of soft metal extending from the shaft housing

(or the rotor housing).

Labyrinth seals are used in gas turbines in two different areas:

In the turbine section, to perform sealing around the rotor. Its job is to minimize escape of gases from high pressure

area to low pressure area.

In the bearing housing, to minimize escape of pressurised air to outside.

If the pressurized air escapes, the lube oil will escape too.

RADIAL TILTING PAD BEARING

RADIAL TILTING PAD BEARING

SHAFT

CASING

Radial Load

Oil WedgeOil Wedge

Shaft

Friction EffectOil Wedge Effect

Oil WedgeOil Wedge

Oil adhere to the rotating shaft

Oil squeeze between shaft and bearing pad forming a solid

oil wedge

RADIAL TILTING PAD BEARING

RADIAL TILTING PAD BEARING

PIN

CASING

OIL

TILTING PAD

SHAFT

RADIAL MAGNITIC BEARINGRADIAL MAGNITIC BEARING

THRUST MAGNITIC BEARINGTHRUST MAGNITIC BEARING

Gas Compressors Sealing SystemGas Compressors Sealing System

COOLER

SCRUBBER

1St Stage

ANTI-SURGE VALVE

COOLER

SCRUBBERANTI-SURGE VALVE

COOLER

SCRUBBERANTI-SURGE VALVE

SCRUBBER

2 Nd Stage 3 Rd Stage

**Centrifugal Compressor Operation **Centrifugal Compressor Operation

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General aspectsGeneral aspects1- A Complete spare balanced rotor to be ideally stored in W.H 2- Compressor will be equipped with a complete surge control system.3- It is advisable to use dry gas seal system instead of wet seal one.

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Compressor Sealing System

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1- Wet seal system ( USINGOILFOR SEALING THE GAS )

1- Wet seal system (USING OIL FOR SEALING THE GAS)

2- Dry Gas Seal ( COMPRESSORGASUSED FOR SEALING THE GAS )

2- Dry Gas Seal (COMPRESSOR GAS USED FOR SEALING THE GAS)

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1 - Wet sealSystem

1 -Wet seal System

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GAS TO FLAREGAS TO FLARE

Drain pot

CLEANSEAL OIL

CLEANSEAL OIL

CLEAN OIL TO

RESERVOIR

CLEAN OIL TO

RESERVOIR

COMPRESSOR GASCOMPRESSOR GASOil sealing system

Oil sealing system

CONTAMINATED OIL TO DISPOSALCONTAMINATED

OIL TO DISPOSAL

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Wet )Oil( sealing system

Wet )Oil( sealing system

GasCompressor rotor

Oil Mech. sealOil Mech. seal

Heater

Oil Tank

Contaminated Oil to disposal

Gas to flare

OIL PUMPS

FILTERS

Drain potDrain pot

19HEATER

SEAL OIL COOLER

FILTERS

OIL PUMPS

SEAL OIL HEAD TANK

REFRENCE LINE

SEAL OIL TANK

Gas to flareGas to flare

Drain pot

Drain pot

Oil to disposalOil to disposal

Oil sealing system

Oil sealing system Opened

20HEATER

SEAL OIL COOLER

FILTERS

OIL PUMPS

SEAL OIL HEAD TANK

REFRENCE LINE

SEAL OIL TANK

Gas to flareGas to flare

Drain pot

Drain pot

Oil to disposalOil to disposal

In case of power failure

In case of power failure

Closed

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Typical Seal Oil Trap ( Drain pot )Typical Seal Oil Trap ( Drain pot )Typical Seal Oil Trap ( Drain pot )Typical Seal Oil Trap ( Drain pot )

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LUBE OIL SYSTEM

LUBE OIL SYSTEM

G box

Electric Motor

Centrifugal Compressor

Lube Oil Drain HeaderTo Main Lube Oil Reservoir

LSC

HSC

From Lube Oil Control Valve

7000 mm Above Machine C/L

Rundown Tank

Lube Supply Oil Header

To Lube Oil Reservoir

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IF THE SEAL IS DETERIORATED, THE SEAL OIL CONSUMPTION WILL INCREASE TO BE MORE THAN

500 LITRES PER DAY.

In case of Wet seal systemIn case of Wet seal system

THE RECOMMENDED SEAL OIL CONSUMPTION IS ABOUT

40 LITRES PER DAY.

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2 - Dry gasseal system

2 -Dry gas seal system

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• NO WEAR DURING ROTATION • NO WEAR DURING ROTATION

StationarStationary Ringy Ring

Wet Seal (contact faces)

Wet Seal (contact faces)

RotatinRotating Ringg Ring

StationarStationary Ringy Ring

RotatinRotating Ringg Ring

Dry gas Seal (Non contact faces)

Dry gas Seal (Non contact faces)

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• NO WEAR DURING ROTATION • NO WEAR DURING ROTATION

ROTATING ELEMENT STATIONARY ELEMENT

GAP

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History of Dry Gas SealsHistory of Dry Gas Seals

• 1925 to 1964 spiral groove bearing technology

• 1968 Curved face seal with spiral grooves

• 1970 Light duty gas seal (Type 28LD) developed for motors

• 1988 Light duty gas seal (Type T28) for gas compressors

• 1992 Introduction of a double gas seal for process pumps

– 1992 Big bore seal chambers

– 1995 Standard bore seal chambers

• 1995 Introduction of a metal bellows gas seal

• 1997 Introduction of High Pressure compressors/pumps seal

• 1997 Introduction of Slow Speed mixer seal

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Rotary Carbon RingsRotary Carbon RingsSpiral GrooveSpiral Groove

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Rotating Mating Ring

Spiral Groove Sealing SurfaceSpiral Groove Sealing Surface

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CarbonRing

TungstenRing

Spiral grooves

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Groove diameter

Spiral grooves

Tungsten carbide ring

(Principle of operation)

Rotating or stationary ring

Rotating or stationary

ring

GAS

Sealing dam

BEFORE ROTATION

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GAS

Rotating or stationary ring

Rotating or stationary

ring

AFTER ROTATION

Groove diameter

Spiral grooves

Sealing dam

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Gas Rushes into spiral grooves

Gas

Gas

Gas

Gas

Gas

Gas

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Spiral Groove OperationSpiral Groove Operation

• Gas pressure rises along spiral grooves

• Contact eliminated

• Cushion of gas

separates sealing faces

Gas Enters And is Induced Towards the Center

Gas is Compressed and Pressure Increases to Set Sealing Gap

Sealing Dam

Rotational direction

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HOW DRY SEAL

WORKS

HOW DRY SEAL

WORKS

P Port 1

Separation barrier

Port 2 Port 3 Port 4 Port 5

Inner seal

Outer seal

Labyrinths

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Filtered process gas inlet process gas

+buffer gas TO FARE

Supply of buffer gas

VENT

buffer gas to separation barrier

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P4

P4

Filtered process gas inlet

Filtered process gas inlet

Balancing Pressure

Room

Balancing Pressure

Room

Ph

PhPs

Ps

BALANCING DRUM

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P

Separation barrier

Inner seal

Outer sealLabyrinths

Port 3 Port 5Port 4

Port 1

Note 2: Velocity 3 – 5 m/s

Port 1 : Filtered process gas inlet

Port 2 : PRIMARY VENT To flare process gas + buffer gas

Port 3 : Supply of buffer gasPort 4 : SECONDRY VENT

Port 5 : Buffer gas to separation barrier

Port 2

Note 1: Maintain a differential of 0.2 barP

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2 -Low pressure in primary vent

( Port2) due to defective secondary seal.

2 -Low pressure in primary vent

( Port2) due to defective secondary seal.

REMARKSREMARKS PPort 1

Separation barrier

Port 2

Port 3 Port 4 Port 5

In seal

Out seal

1- High pressure )due to excess flow(

in primary vent.

2- Low buffer gas pressure.

1- High pressure )due to excess flow(

in primary vent.

2- Low buffer gas pressure.

ALARMALARM1 -High diff. P across

filter of:

afiltered process gas - .

b.buffer gas -

1 -High diff. P across

filter of:

a- filtered process gas .

b- buffer gas.

ALARM and TRIPALARM and TRIP

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3 -BUFFER GAS TO SEPARATION ZONE

TO PREVENT JOURNAL BEARING OIL TO GET IN MECHANICAL SEAL

1-FILTERED GAS

TO PREVENT PRODUCT GAS LEAK

2 -SUPPLY OF BUFFER GAS ) N2 OR AIR (

TO PRVENT FILTERED GAS LEAK

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SealChamber

FlowMeter

Non-Contacting Seals

Dry Nitrogen CircuitDry Nitrogen Circuit

BallValve

PressureGage

PressureRegulator

NitrogenSource

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Mechanical seal and bearings arrangementMechanical seal and bearings arrangement

oilnitrogen

EquipmentEquipment

nitrogenSeal gas

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WHY TO USE DRY SEAL INSTEAD OF WET SEALWHY TO USE DRY SEAL INSTEAD OF WET SEAL

• PERMITS HIGHER VELOCITY&PRESSURE

• NO SEAL OIL CONSUMPTION

• NO GAS / OIL CONTAMINATION

• NO WEAR

• LOW POWER CONSUMPTION

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Dry Gas seal is

a self adjusting Seal

Dry Gas seal is

a self adjusting Seal

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Spiral grooves

Groove diameter

Inner diameter

Sealing dam

Rotating ringTungsten carbide

)Principle of operation(

Rotating ring

Carbon ring

GAS

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Closing forceFC

Spring load

Productpressure

Forces acting on the sealForces acting on the seal

Compression

Expansion

Gas filmPressure distribution

FOOpening forceFC = FO

Normal operation

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If Gap increasedIf Gap increased

Closing forceFC

Spring load

Productpressure

Compression

Expansion

Gas filmPressure distribution

FOOpening force FC FO

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Closing forceFC

Spring load

Productpressure

Compression

Expansion

Gas filmPressure distribution

FOOpening force

Gap will be reducedGap will be reduced

FC FO

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Back To Normal operationBack To Normal operation

Closing forceFC

Spring load

Productpressure

Compression

Expansion

Gas filmPressure distribution

FOOpening forceFC = FO

Normal operation