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DRY GAS SEALS

DRY GAS SEALS. Dry gas seals are 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

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DRY GAS SEALS

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  1. DRY GAS SEALS

  2. Dry gas seals are 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.

  3. Dry Gas Seal Arrangement

  4. Typical Dry gas seal

  5. Seal Face of Dry gas

  6. Lift off of stationary ring achieved by increased pressure at the taper portion. Theory of Non-Contact Demo

  7. Dry Gas Seal Arrangement in K-2115/K-4115

  8. Dry Gas Seal Arrangement in K-2115/K-4115

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

  10. Dry Gas Seal Supply Console - P&ID

  11. Understanding Seal Gas Supplies to Dry Gas Seal Primary Seal • 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

  12. Understanding Seal Gas Supplies to Dry Gas Seal Secondary Seal ( Containment 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

  13. 1 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. 2 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 Reverse Pressure Reverse pressure under static condition will result in an increase in static leakage. Under Dynamic condition, reverse pressure can result major damage to the Dry Gas Seal System components. Slow Roll 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

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