Compressor Dry Gas Seal

[cancer7782]

Dear all,

I would like to get some opinion regarding the use of dry gas seal in centrifugal compressor. During compressor blowdown, is seal gas still required to be supply to the compressor? Normal seal gas supply is process gas from compressor discharge. Appreciate your valuable opinion.

Thanks.

[pipingren]

Yes, it is required. Positive pressure shall be maintained for primary seal port to avoid any dirt, dust or liquid entry into primary seal surface, even during blowdown period of the compressor. Normally we will design one air booster pump in primary seal, which can boost the gas taken from the compressor discharge up to 1brag or 2barg higher, which can effectively secure the dry gas seal system.