Centrifugal compressor
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What is the principle behind the lubrication of the isolation gas seal in centrifugal compressors?
The pressure of the isolation gas is higher than that in the bearing housing; nitrogen leaks into the bearing housing through the comb seal, preventing lubricating oil from entering the dry gas seal. However, it is necessary to maintain a certain distance between the bearing and the dry gas seal; otherwise, oil will still enter the seal.
Simply put, it serves as a nitrogen barrier that prevents oil and gas from entering the dry gas seal.
All compressor dry gas seals should be equipped with a rear isolation seal. Its function is to prevent bearing oil from contaminating the dry gas seal, and at the same time to stop any gases leaking from the dry gas seal from entering the bearing oil side. Rear isolation seals can be of the labyrinth type or those with carbon rings; carbon ring seals consume less nitrogen, approximately 20%-30% of what labyrinth seals of the same size require, and they also offer better oil resistance. However, their installation and maintenance on-site can be somewhat more complicated