Analysis of Vibration Characteristics of Centrifugal Pump Mechanical Seal under Wear and Damage Degree

Abstract

Mechanical seal is a kind of shaft sealing equipment. Face wear is one of the main causes of mechanical seal failure. Mechanical seal condition is also related to the reduction of energy consumption and carbon emission. Therefore, we need to detect the centrifugal pump seal condition. At present, vibration signal is a common method for fault monitoring and diagnosis of centrifugal pump. In this paper, the vibration signal under the condition of damaged centrifugal pump seal is measured by studying the characteristics of vibration signal after the end face damage of centrifugal pump. Statistical indicators such as RMS and kurtosis were taken to analyze the average energy and shock wave energy of vibration signal. The time-frequency characteristics of vibration signal are analyzed by frequency spectrum. The results show that there are a large extent variation of vibration amplitude in the direction of base and axis and a weak variation of vibration amplitude in the direction of radial and vertical. With the increasing of flow rate, the RMS of vibration signal falls at first, then keeps steady, and mounts at last when the flow rate is over the design flow rate. It can be shown from the time-frequency spectrum that there is a shock wave and pause signals caused by the shock wave, which are reflected by the higher frequency band components of the vibration signal that can provide a reference to the diagnosis of the occurrence of damaged mechanical seal. From the analysis, the energy of vibration signal is related to the running condition, we can find that the occurrence of mechanical seal wear makes the centrifugal pump to produce high-frequency vibration signal, and the axial vibration is the strongest and the instability in the fluid makes the vibration signal produce high amplitude characteristics. Analyzing the vibration signal characteristics of centrifugal pumps with damaged mechanical seal is of great significance to find the mechanical seal failure of the centrifugal pumps and adjust the operating parameters.