Vibration analysis and control of oil-free process screw compressor discharge piping system

While screw compressors are widely regarded as suitable for butadiene delivery due to their liquid-injection capability and precise temperature control, severe vibration in the discharge piping system has remained a key issue threatening the long-term safe operation of such units. This paper presents a systematic study on the abnormal vibration observed in the discharge pipe of a butadiene screw compressor, including mechanism analysis, numerical simulation, and vibration reduction optimization. Vibration testing and spectrum analysis first show that the dominant vibration frequency is 395 Hz, consistent with the second harmonic of the compressor operating frequency. Based on plane wave theory and vibration principles, the gas pulsation and modal characteristics of the piping system are analyzed. It is confirmed that the abnormal vibration originates from structural resonance triggered by gas pulsation. To address the poor attenuation performance of the original two-chamber impedance composite silencer at 395 Hz, an improved three-chamber silencer is proposed. Field application shows that the vibration displacement at the silencer is reduced to less than 27 μm. The horizontal vibration across the whole piping decreases by at least 30%, while vertical vibration falls by no less than 50%. The whole pipe now operates within a safe vibration range. This study systematically explains the resonance mechanism responsible for discharge piping vibration in screw compressors and verifies the effectiveness of silencer optimization as a source control method. It provides both theoretical support and engineering guidance for vibration control in similar compressor units.