How does dry gas seal work?
Dry gas seals are non-contacting, dry-running mechanical face seals that consist of a mating (rotating) ring and a primary (stationary) ring. When operating, lifting geometry in the rotating ring generates a fluid-dynamic lifting force causing the stationary ring to separate and create a gap between the two rings.
What is seal gas system?
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. Inboard of the dry gas seal is an inner labyrinth seal, which separates the process gas from the gas seal.
What is dry gas seal hang up?
It is common for dry gas seals to exhibit excessive leakage to the primary vent immediately on startup after extended periods of compressor downtime. This condition, known as hang up, occurs when the balance diameter o-ring “sticks” to its mating (sliding) surface because of friction.
What is the purpose of seal gas in compressor?
Compressor process seals are designed to seal the rotating assembly in the stationary compressor case to prevent the process gas in the compressor from getting to the atmosphere and to prevent the atmosphere from getting into the process gas.
What gas is used for seal gas?
nitrogen
The seal or barrier gas, typically nitrogen, is introduced at a pressure of 0.2 Mpa (3psi) higher than the product pressure.
What is a drydry gas seal?
Dry Gas Seals (DGS) 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.
Why do the faces of dry gas seals contact during slow roll?
The faces of a dry gas seal can contact during slow roll if hydrostatic, or hydrodynamic forces are not adequate to achieve seal face liftoff.
What is a sealing gas used for?
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. Primary Dry Gas Seal: Preventing leakage of working gas from a machine’s inner side. Secondary Dry Gas Seal: Backing up the first dry gas seal.
What are the requirements of a dry gas seal control system?
A dry gas seal control system must have an adequate range and controllability to maintain a minimum 16 fps (4.9 m/s) gas velocity across the inner process labyrinth as well as at the labyrinth clearances ranging from the minimum to the maximum and up to two times the maximum design clearance.