DRY-GAS-SEAL.ppt dgs details has been given to be seen

dgs more details has been given in the data to be seen

1. failure of components.

2. •No seal wear –minimum seal maintenance
•No oil film –eliminates complex, heavy & expensive oil
feed system
•Low power consumption
•Improved Rotor system stability –unlike unpredictable oil
rings seals
•Improved operational safety –eradicates buildup of HC
gas in seal oil
Advantages of DGS

3. •Constructional Features
•Dry Gas Seals-Main seal
•Barrier Seals
•Gas seal support systems

4. •Dry gas sealsare basically mechanical face seals
•consisting of a mating (rotating) ring and a primary (stationary)
ring
•During operation, grooves in the mating ring generate a fluid-
dynamic force
•causing the primary ring to separate from the mating ring, thus,
creating a "running gap" between the two rings.
•A sealing gas is injected into the seal, providing the working
fluid for the running gap and the seal between the atmosphere
or flare system and the compressor internal process gas.

6. Seal Face of Dry gas

10. F 1
F 2
FIT
FLARE
SECONDARY
&
SEPARATION GAS SUPPLY
N2
PRIMARY SEAL GAS SUPPLY
FROM COMPRESSOR DISCHARGE
START UP SUPPLY N2
PCV
PCV
FIT

11. Primary Seal Gas is, typically, Filtered gas from the compressor discharge
side, injected in to the Seal Chamber (the primary inboard seal chamber)
A major part of the this injected gas will flow back to the compressor through
the inner labyrinth at the process gas side.
This achieves the prevention of emissions from the compressor to the
atmosphere.
A small quantity of gas will pass thro the dynamically separated gap of seal
faces to the intermediate chamber between the inboard &outboard seals
Since this cavity is vented, the rate ( quantity per minute) of gas flowing out
is measured downstream.
This is the indication of the leakage rate of the seal.
A minimum rate of leakage will be always present. Increase in the rate of
leakage beyond design limits indicates reduced seal performance/ Efficiency
Seal Gas Supplies to Dry Gas Seal

12. Seal Gas Supplies to Dry Gas Seal
Secondary Seal is a backup seal which seals the leakage
from primary seal chamber
Nitrogen is injected in to this secondary Seal Chamber
The Secondary Seal Functions as a safety seal to avoid emissions to
atmosphere in case of excessive leakage in the primary seal
Separation seal ( Barrier seal)
This seal also works in conjunction with a separation labyrinth situated
between the bearing housings and Seal Chambers
The separation gas is also Nitrogen, injected in to the separation labyrinth
The main purpose of Separation gas supply is to prevent the oil in the bearing
side from entering the seal Chamber.
Presence oil in the seal chamber will cause
damage to the Dry gas seal components
Secondary Seal

13. Operational Guide Lines –Dry Gas Seals
Seal Gas Supply Quality
The Quality of Gas fed to the seals must be clean and Dry-
Coalescing Filters to filter 2 microns shall be used in the
Dry gas Supply Console. Pressure Drop across the Filters shall be
monitored and filters must be renewed to achieve good seal performance
Seal Gas Supply flow
The seal gas supply flow must be sufficient enough to ensure that the seal is
Supplied with sufficient filtered gas during operation with excess gas going back
in to the Compressor casing. This is will provide an ideal sealing environment
to maintain the optimum seal performance
Seal Gas Leakage Trends
Seal performance is monitored through leakage trends. Occasional Spikes
In the leakage due process parameter variations, shaft movement, speed changes
are no cause for alarm. But persistent trend of higher leakage may give a
forewarning of seal problems

14. Operational Guide Lines –Dry Gas Seals
Reverse Rotation
Reverse Rotation should be avoided as it will damage the delicate parts of
a Dry Gas Seal
In Turbine Driven compressors Slow roll below 1000 rpm be avoided.
The separation of seal faces will not be achieved under such condition.
Seal faces will be running with contact which will damage
the geometry of the grooves in the seal face
Slow Roll

15. THANK YOU