Study on The Violent Vibration Mechanism of Polye thylenee Mother Liquid Pump and Pipeline

Abstract In the single test stage, two high density polyethylene mother liquid pumps and pipeline was seen the violent vibration. The vibration value of the pump was up to 26.2mm/s, into the vibration classification D, and the vibration value of the inlet pipe and outlet pipe was up 59.4mm/s and 38.8mm/s respectively, seriously exceeding the standard. BH 550 offline state monitoring system was used to diagnose the mother liquor pump and pipeline. Found that the peak vibration frequency of pump body and pipeline was 64Hz, which was inconsistent with the fault frequency of coupling side and non-coupling bearing. No obvious effect had been achieved through the adjustment and transformation of pipeline support, the change of pipeline natural frequency and the elimination of pipeline stress piping. It was confirmed that the small balance hole of the impeller causes the medium pressure pulsation of the pump suction port due to the flow state analysis of the impeller inlet. The medium cavitation affects the excitation frequency. The instability of the medium flow state of the mother liquid pump was the fundamental cause of the violent vibration of the pump body and pipeline. According to the vibration analysis and high pump bearing temperature, the violent vibration of mother liquor pump and inlet and outlet pipeline had been eliminated by expanding the balance hole diameter of mother liquor pump impeller from 11.9mm to 16mm.