Labyrinth seal into two halves

Labyrinth Seal

Labyrinth Seal

Labyrinth seal consist of a series of circumferential 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 CASING SHAFT Radial Load

Oil Wedge Friction Effect Oil Wedge Effect Shaft

Oil Wedge Oil adhere to the rotating shaft Oil squeeze between shaft and bearing pad forming a solid oil wedge Oil adhere to the rotating shaft

RADIAL TILTING PAD BEARING SHAFT PIN OIL CASING

RADIAL MAGNITIC BEARING

THRUST MAGNITIC BEARING

Gas Compressors Sealing System

** Centrifugal Compressor Operation SCRUBBER ANTI-SURGE VALVE SCRUBBER ANTI-SURGE VALVE SCRUBBER ANTI-SURGE VALVE SCRUBBER COOLER COOLER COOLER 1St Stage 2 Nd Stage 3 Rd Stage

General aspects 1- 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. 14

Compressor Sealing System 1- Wet seal system ( USING OIL FOR SEALING THE GAS ) 2- Dry Gas Seal (COMPRESSOR GAS USED FOR SEALING THE GAS ) 15 15

1- Wet seal System 16

Oil sealing system CLEAN SEAL OIL GAS TO FLARE CONTAMINATED COMPRESSOR GAS GAS TO FLARE CLEAN OIL TO RESERVOIR Drain pot CONTAMINATED OIL TO DISPOSAL CLEAN SEAL OIL 17

Gas to flare Wet (Oil) sealing system Contaminated Oil to disposal Compressor rotor Oil Mech. seal Heater Oil Tank Gas to flare FILTERS Drain pot Drain pot Contaminated Oil to disposal OIL PUMPS 18

Oil sealing system Opened Gas to flare Oil to disposal 19 REFRENCE LINE SEAL OIL HEAD TANK Opened Gas to flare FILTERS Drain pot Drain pot Oil to disposal OIL PUMPS SEAL OIL COOLER 19 SEAL OIL TANK HEATER

In case of power failure REFRENCE LINE SEAL OIL HEAD TANK Closed Gas to flare FILTERS Drain pot Drain pot Oil to disposal OIL PUMPS SEAL OIL COOLER 20 SEAL OIL TANK HEATER

Typical Seal Oil Trap ( Drain pot ) 21

LUBE OIL SYSTEM To Main Lube Oil Reservoir Lube Oil Drain Header From Lube Oil Control Valve 7000 mm Above Machine C/L Rundown Tank Lube Supply Oil Header To Lube Oil Reservoir LUBE OIL SYSTEM Electric Motor G box Lube Oil Drain Header To Main Lube Oil Reservoir Centrifugal Compressor LSC HSC 22

In case of Wet seal system THE RECOMMENDED SEAL OIL CONSUMPTION IS ABOUT 40 LITRES PER DAY. IF THE SEAL IS DETERIORATED, THE SEAL OIL CONSUMPTION WILL INCREASE TO BE MORE THAN 500 LITRES PER DAY. 23

2- Dry gas seal system 24

NO WEAR DURING ROTATION Rotating Ring Stationary Ring Rotating Ring Stationary Ring Wet Seal ( contact faces ) Dry gas Seal ( Non contact faces ) 25

NO WEAR DURING ROTATION ROTATING ELEMENT STATIONARY ELEMENT GAP 26

History 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 27

Spiral Groove Rotary Carbon Rings 28

Spiral Groove Sealing Surface Rotating Mating Ring 29

Spiral grooves Carbon Ring Tungsten 30

( Principle of operation) Rotating or stationary ring Rotating or stationary ring GAS Spiral grooves Sealing dam Groove diameter Tungsten carbide ring BEFORE ROTATION 31

GAS Spiral grooves Sealing dam AFTER ROTATION Rotating or stationary ring Rotating or stationary ring Spiral grooves Sealing dam Groove diameter AFTER ROTATION 32

Gas Rushes into spiral grooves Gas Gas Gas Gas Gas Gas 33

Spiral Groove Operation Gas Enters And is Induced Towards the Center Gas is Compressed and Pressure Increases to Set Sealing Gap Sealing Dam Rotational direction Gas pressure rises along spiral grooves Cushion of gas separates sealing faces Contact eliminated 34

HOW DRY SEAL WORKS 35

Filtered process gas inlet buffer gas to separation barrier Supply of buffer gas buffer gas to separation barrier process gas + buffer gas TO FARE VENT P Port 1 Separation barrier Port 2 Port 3 Port 4 Port 5 Inner seal Outer seal Labyrinths 36

P4 BALANCING DRUM Filtered process gas inlet Ph Ps Ps Ph Balancing Pressure Room Filtered process gas inlet P4 Ph Ps Ps Ph BALANCING DRUM 37

Port 1 : Filtered process gas inlet Separation barrier Inner seal Outer seal Labyrinths Port 4 Port 1 : Filtered process gas inlet Port 2 : PRIMARY VENT To flare process gas + buffer gas Port 3 : Supply of buffer gas Port 4 : SECONDRY VENT Port 5 : Buffer gas to separation barrier Note 1: Maintain a differential of 0.2 bar P Note 2: Velocity 3 – 5 m/s 38

REMARKS ALARM ALARM and TRIP 1- High diff. P across 2- Low pressure in Port 1 Separation barrier Port 2 Port 3 Port 4 Port 5 In seal Out seal ALARM 1- High diff. P across filter of : a- filtered process gas. b- buffer gas. ALARM and TRIP 2- Low pressure in primary vent (Port2 ) due to defective secondary seal. 1- High pressure (due to excess flow) in primary vent. 2- Low buffer gas pressure. 39

TO PREVENT PRODUCT GAS LEAK 1-FILTERED GAS TO PREVENT PRODUCT GAS LEAK 2- SUPPLY OF BUFFER GAS ( N2 OR AIR ) TO PRVENT FILTERED GAS LEAK 3- BUFFER GAS TO SEPARATION ZONE TO PREVENT JOURNAL BEARING OIL TO GET IN MECHANICAL SEAL 40

Dry Nitrogen Circuit Non-Contacting Seals Pressure Gage Regulator Ball Valve Pressure Gage Regulator Nitrogen Source Flow Meter Seal Chamber 41

oil Seal gas nitrogen nitrogen Mechanical seal and bearings arrangement Seal gas nitrogen Equipment nitrogen oil 42

NO SEAL OIL CONSUMPTION WHY TO USE DRY SEAL INSTEAD OF WET SEAL NO SEAL OIL CONSUMPTION NO GAS / OIL CONTAMINATION NO WEAR LOW POWER CONSUMPTION PERMITS HIGHER VELOCITY&PRESSURE 43

Dry Gas seal is a self adjusting Seal 44

( Principle of operation) Spiral grooves Groove diameter Inner Sealing dam Rotating ring Carbon ring GAS Rotating ring Tungsten carbide 45

Pressure distribution Forces acting on the seal Compression Expansion Gas film Pressure distribution FO Opening force Closing force FC FC = FO Normal operation Spring load Product pressure 46

Pressure distribution If Gap increased Compression Expansion Gas film Pressure distribution FO Opening force Closing force FC Spring load Product pressure FC FO 47

Pressure distribution Gap will be reduced FC FO Compression Expansion Gas film Pressure distribution FO Opening force Closing force FC Spring load Product pressure 48

Pressure distribution Back To Normal operation Compression Expansion Gas film Pressure distribution FO Opening force Closing force FC Spring load Product pressure FC = FO Normal operation 49