AVTN Vertical compressors meets API 692 requirements for Dry Gas Seals Boosting
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. These seals are typically used in Axial, Centrifugal, Rotary Screw Compressors and Expanders operated in a harsh working environment such as oil exploration, extraction and refining, petrochemical industries, gas transmission and chemical processing.
In order to avoid contamination from solid and liquids, dry gas seals are constantly purged with clean gas that is coming from the process compressor (auto-buffering) or from an external source (dedicated booster).
The dry gas seal system is one of the key auxiliaries to ensure flawless and smooth operation of the above-mentioned rotating equipment. The correct operation of the dry gas seals requires a precise control of the pressures and flows of treated gas that is feeding them in order to assure the level of required reliability.
Such system is composed by several components (external to the rotating machine), such as:
- Filters
- Boosters
- Heaters
- Instrumentation and measurement systems for flows, pressures and temperatures
- Piping
Although this tecnology has been widely applied in the Oil and Gas sector since mid ’70 to replace other lubricated seals, only in June 2018 the American Petroleum Institute, which standards are governing since decades the oil and gas industry, issued the first edition of the API692 “Dry Gas Sealing Systems for Axial, Centrifugal, Rotary Screw Compressors and Expanders”.
This standard now defines design criteria and operational requirements for the dry gas seals and its system and it is becoming a reference for operators and manufacturers.
One of the key elements of the Dry Gas Seal system is the booster compressor. The booster compressor is used:
- To feed Dry Gas Seal during pressurized process compressor Stop (in order to avoid contamination from solid and liquids due to the lack of auto-buffer)
- As alternative source of seal gas during normal operation in case the plant operation or process gas quality cannot allow centrifugal compressor auto-buffering
GI&E Engineers have recently assessed the API 618 AVTN vertical reciprocating compressors against the duties required by such application, governed by API692.
The result of this analysis shows that the AVTN vertical reciprocating compressor meets the requirements of API692, in particular:
- AVTN booster series with different cylinder configuration can provide Seal Gas flow more than 30 m3/h and differential pressure even more than 10 bar with max sealing pressure of 300 bar covering the requirement of wide range of compressors and applications.
- AVTN series booster has flanged connections according to Project rating.
- AVTN series booster can be an alternate Seal Gas supply taking gas from different source and with twin configuration can have time between maintenance of 16000 hours. With different cylinders configuration can provide Seal Gas flow even more than 30 m3/h with max sealing pressure of 300 bar.
- It may be used also as startup booster for low-pressure compressor like refrigeration compressor avoiding to inject uncompatible gas in the process.
- AVTN series booster complies with all the requirements specified in Par. 7.4 (Booster).
AVTN reciprocating compressor can be supplied as a stand-alone unit or with a compact skid including frame, electric motor, pulsation dampeners and lube oil system.