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DRY GAS SEAL
OPERATION
Presented by
M. Safdar Amin
Contents
INTRODUCTION
CONSTRUCTION
WORKING
DRY GAS SEAL SYSTEM
DRY GAS SEAL ( DGS ) DATA
CONCLUSION
COMMON PROBLEM
ADVANTAGES OF DGS
Introduction
Dry gas seal is a non-contacting type
mechanical seal which works on the principles
of hydrodynamic forces to create and maintain
precisely defined gap during operation.
Seal location on Compressor
Bearing
Bearing
Seal components
Seal in ‘Tandem’ Arrangement
Rotating ring
Rotating ring
Secondary Seal Primary Seal
Stationary ring Stationary ring
Working of DGS
Secondary seal Primary seal Process side
Compressor shaft
Seal gas supply Primary vent Buffer gas supply Secondary vent
Spiral Groove Sealing Surface
clockwise
shaft rotation
outer diameter
Opposing
face inner
diameter
spiral
groove
Sealing dam
Rotating Ring
Inner
groove
diameter
Spiral Groove Operation
Direction of Rotation Gas Enters
And is Induced
Towards the
Center
Gas is Compressed and
Set Sealing Gap
Sealing Dam
Unidirectional Bidirectional
Compression
Expansion
FC=FO FC
Closing Force
S P
S = Spring Load
P = Hydrostatic Load
FO
Opening Force
Gas Film Pressure
Distribution
P3
Sealing Dam
Grooves
Significant hydrodynamic effect within grooved portion
Maximum pressure achieved P3
Linear pressure drop across seal dam to ID
Seal Pressure Profile
Seal Control Systems
Original Seal Gas Supply System Modified Seal Gas Supply System
cooler
DGS Data At Expansion Unit No
. Description Syn Gas Amm.
1 Arrangement Tandem Tandem
2 Design Pressure 77 Kg/cm2 4.9 Kg/cm2
3 Design Temperature 43 0C 43 0C
4 Injection (seal) Gas from
Recycle
discharge 2nd Stage
6 N2 Supply Pressure 0.2 Kg/cm2 0.2 Kg/cm2
7 Primary Vent Pressure (operating)
0.15-0.2
Kg/cm2
0.05-0.1
Kg/cm2
8
Secondary Vent Pressure
(Operating) 0.22 kg/cm2 0.22 kg/cm2
9
∆P Injection gas and balancing gas
(operating) 0.4 Kg/cm2 0.34 Kg/cm2
11 Injection Gas Adjustment Bean Choke Bean Choke
Common Problems
Seal Contamination
Elastomers
Seal Contamination
Process Side
Seal Gas Supply
Bearing Lube Oil
Source
Results
Dirt Moisture
Seal hang ups
Wear of faces
Corrosion
Wear of faces
Elastomers
Limitations
Temperature
Pressure
Results
Loss of Elasticity
Advantages of DGS
Low Maintenance Cost
Less Space
Less Utility Consumption
Prohibits Intermixing Of Fluids
Less Environmental Hazards
Conclusion
Dry gas seal (DGS) is a state of the art technology
and an efficient tool in improving plant reliability
THANK YOU !
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