Dry Gas Seals for Compressors 

Polymer Dry Gas Seal for Low Temperature applications                    Tmin     =    -170°C

Figure 1 -  Dry Gas seal for low temperature

Figure 2 - Tandem Dry Gas Seal with internal labyrinth

Figure 3 - Centrifugal Compressor

Why Dry Gas Seals ?

• No oil usage
• High reliabilty
• High Safety
• Low Maintenance Costs
• Low Operating Costs
• Low Process Gas Losses
• Environmental Concerns
• Operating Simplicity

Dry Gas Seal components

Figure 4 - Dry Gas Seal components

Forces

Figure 5 - Forces

Reaction to transients

Figure 6 - Reaction to transients

uni - directional, V - Groove

Figure 7 - uni - directional, V - Groove

Dry Gas Seal Principle V-groove

Figure 8 - Dry Gas Seal Principle V-groove

bi - directional, U - Groove

Figure 9 - bi - directional, U - Groove

Dry Gas Seal Principle U-groove

Figure 10 - Dry Gas Seal Principle U-groove

Dry Gas Seal Principle U-groove

Figure 11 - Dry Gas Seal Principle U-groove

sloped groove bed

Figure 12 - sloped groove bed

Seal face material combinations

Figure 13 - Seal face material combinations

Seal face characteristics

Figure 14 - Seal face characteristics

Dry Gas Seal Arrangements

Single seal arrangement 

Figure 15 - Single seal arrangement

Tandem seal arrangement

Figure 16 - Tandem seal arrangement

Tandem seal with internal labyrinth

Figure 17 - Tandem seal with internal labyrinth

Double seal arrangement

Figure 18 - Double seal arrangement

Seals with O-rings can have the following problems

Figure 19 - Seals with O-rings

For some applications the better solution is the Burgmann Polymer Dry Gas Seal (PDGS)

• no chemical problems
•   no extrusion
•   no explosive decompression
•   no mechanical wear

  result in:  NO HANG UP

Seal configuration Why no hang up

Burgmann Polymer Dry Gas Seals have no hang up because extrusion of secondary sealing elements is not possible due to optimised gaps. Small gaps are possible by using materials with about the same thermal expansion coefficients - Silicon carbide for seal faces and rotating seats and Tungsten carbide for sleeves and back up rings

Figure 20 - Seal configuration

DRY GAS SEAL Operating limits:

• Pmax = 250 bar
• Vgmax = 200 m/s
• Vgmin = dependent on seal design has to be checked!
• Tmax = +230 °C
• Tmin = -170 °C

Current Methods of Sealing Compressors

Figure 21 - Sealing Compressors

Current Methods of Sealing Compressors - Labyrinths

Figure 22- Sealing Compressors - Labyrinths

• Limited application
• Low pressures
• Services such as air, oxygen, chlorine
• High leakage (excessive buffer use)
• Low initial seal cost
• Wear during operation / loose efficiency
• Can require elaborate control systems

Current Methods of Sealing Compressors  ( Circumferential Carbon Seals)

Figure 23 - Current Methods of Sealing Compressors

• Limited application
• Low pressures
• Services such as chlorine
• Moderate leakage (2-3 times < labyrinth)
• Low to moderate initial seal cost
• Wear during operation / lose efficiency

Current Methods of Sealing Compressors  (Oil Film Seals)

Figure 24 - Current Methods of Sealing Compressors  (Oil Film Seals)

• Pressure Range 0-275 bar
• Oil contamination of the process gas
• Requires minimum pressure / flow to cool
• Wear during operation / lose efficiency
• Elaborate control system
• High power losses

Current Methods of Sealing Compressors  (Oil Lubricated Mechanical Seals)

Figure 25 - Current Methods of Sealing Compressors  (Oil Lubricated Mechanical Seals)

• Limited in speed and pressure
• Oil contamination of the process gas
• Requires minimum pressure / flow to cool
• Wear during operation / limited life
• Elaborate control system
• High power losses

 Why Dry Gas Seals ?

• No oil usage
• High reliabilty
• High Safety
• Maintenance Costs
• Operating Costs
• Process Gas Losses
• Environmental Concerns
• Operating Simplicity

Dry Gas Seal Materials

Figure 26 - Dry Gas Seal Materials

Magnitudes of different face materials

Figure 27 - Different face materials

Essentials of Groove Design

Figure 28 - Essentials of Groove Design

Groove entry angle alpha

Figure 29 - Groove entry angle alpha

uni - directional, V - Groove

Figure 30 - uni - directional, V - Groove

Dry Gas Seal Principle V-groove

Figure 31 - Dry Gas Seal Principle V-groove

bi - directional, U - Groove

Fiigure 32 - bi - directional, U - Groove

Dry Gas Seal Principle U-groove

Figure 33 - Dry Gas Seal Principle U-groove

Advantages of the Burgmann groove design

Figure 34 - Advantages of the Burgmann groove design

Forces

Figure 35 - Forces

Reaction to transients

Figure 36 - Reaction to transients

Gasfilm - stiffness

Figure  37 - Gasfilm - stiffness

Single seal arrangement

Figure 38 - Single seal arrangement

Tandem seal arrangement

Figure 39 - Tandem seal arrangement

Tandem seal with internal labyrinth

 Figure 40 - Tandem seal with internal labyrinth

Double seal arrangement

Figure 41 - Double seal arrangement

Operating limits

Figure 42 - Operating limits

Leakage

Figure 43 - Leakage

Gas Properties

Figure 44 - Gas Properties

Power Loss

Figure 45 - Power Loss