Investigation of process gass compressor shaft vibration phenomena

Case StudyThis paper presents details of investigation results of issues observed during plant start-up on a centrifugal compressor. Compressor was operated with air/ nitrogen during start-up and high shaft vibration (approx. 75 um) were observed on DE side of compressor accompanied by high levels of coast down vibration levels (exceeding alarm levels). This paper presents subsequent detailed rotor dynamics analysis to understand root cause of the high vibrations

Investigation of a Compressor Coupling Failure by Torsional Excitation

Case StudyThis case study examines a repeat compressor coupling failure that was a result of a complex, dynamic interaction of components that excited the 2nd torsional natural frequency of the train. The mature unit had operated successfully for 17 years until a seemingly insignificant series of compromising events created degradation which triggered the excitation of the natural frequencies. The couplings exhibited evidence of fatigue fractures leading to catastrophic failure due to high alternating torsional stress. A natural frequency modal analysis showed that a mode shape of the compressor train bull gear enabled it to interact within the total system torsional modal response to create an excitation frequency at the 2nd torsional natural frequency. Further, discussion on practical design, operation and equipment monitoring shows limitations in guarding against the vulnerabilities mentioned

Dry Gas Seals: General (Installation, Operation, Troubleshooting, and Retrofitting), Controls

Discussion GroupSuggested Topics for Dry Gas Seals Discussion group: • DGS operating characteristics • Unidirectional versus bidirectional • Seals faces and seats, O rings materials • Explosive decompression • Primary seal gas supply control system Primary seal failure detection • Primary seal gas vent to flare control system • Secondary seal failure detection • Tertiary seal types, carbon rings versus labyrinth • Buffer gas and associated control • Separation gas, air or nitrogen and associated controls • Tandem versus double seals application • Field problems and experiences • Challenges in Dry Gas Seal retrofits • Operation and spares maintenance, shelf life and requalification. • Dry Gas seals reliability and availability. • Dew point monitoring and control • Seal Gas Conditioning systems • Seal Gas Boosters and Heaters • API 614 – 5th Edition, current and advancements in Dry Gas seals & System