Vibration identification and reduction of a reciprocating compressor suction bottle with long cantilever structure

Excessive vibration in reciprocating compressor systems can threaten equipment reliability, operational safety, and production continuity. In this study, the root cause and reduction of excessive vibration in a compressor suction system were investigated through vibration testing, modal analysis, transient flow-field analysis, and buckling analysis. Vibration measurements and modal analysis demonstrated that the excessive vibration was not caused by mechanical resonance. Transient flow-field analysis revealed that the intermittent suction process generated significant fluid-induced excitation forces, with the dominant excitation force reaching 63–68 kN in the vertical direction. Buckling analysis showed a minimum critical buckling load of only 6.463 MPa in the horizontal direction, indicating that the long cantilever configuration of the suction bottle provided insufficient structural stiffness and stability. To mitigate vibration, a vibration reduction scheme was proposed that involved shortening the cantilever sections and relocating the inlet nozzle to the axial center of the suction bottle. These structural modifications increased the mechanical natural frequencies and enlarged the frequency separation margin from the compressor excitation frequencies. Moreover, the dominant fluid-induced excitation force in the vertical direction decreased from 63–68 to 51.6–55.1 kN, and the minimum critical buckling load in the horizontal direction increased by 52.57%, from 6.463 to 9.861 MPa. Field implementation verified the effectiveness of the proposed scheme, with vibration velocities reduced by more than 40% and all measured velocities decreasing to below the ISO 20816–1 limit of 18 mm/s. The proposed methodology provides a practical solution for vibration diagnosis, structural optimization, and vibration mitigation in reciprocating compressor systems.