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 !

ANY QUERY ?