Abstract
This paper is focusing on diagnosis for longitudinal and radial vibrations of turbomachinery coupled with induction motors. In this context, extensive field vibration measurements are conducted and analysed to identify the source of predominant vibrations on rotor bearing system in a chosen centrifugal compressor in the radial and longitudinal directions. As a first step, the measured overall vibration levels at multiple locations on bearing surface are compared with the existing ISO standard limits. These measurements showed severe longitudinal vibration values and failure of thrust collar assembly which were not considered in turbomachinery (API) design standards. The second step in diagnosis for vibration spectrum measurements are conducted both in longitudinal and radial directions during transient and steady state operations to find the vibration source and thrust collar assembly failure mechanism. This study on vibration diagnosis and analysis on turbomachinery is useful in correcting the severe longitudinal vibrations and damage control measures and corrections associated with static eccentric airgaps through motor air gap diagram.
Highlights
Refinery service industry uses turbomachinery with coupled induction motors
The measured vibration levels for the above turbomachinery exceed the allowable limits according to the standard ISO 10816-3 and ISO 7919-3 for couped industrial machines classification. the allowable vibration velocity for group I machinery with power rating above 300 kW and installed at a rigid support is up to 2.8 mm/s rms, and its exceedance causes damages to the machine [4, 5]
The longitudinal vibrations at location 3 presented in Table 3 produced in the tune with the vibration amplitude other directions and the thrust force generated in the motor rotor skewed bar and combined static eccentric air-gap effect as discussed in the reference [7, 8]
Summary
Refinery service industry uses turbomachinery with coupled induction motors. These turbomachinery’s are designed according to the API standards. The operational safety limits of these machines are established based on radial and longitudinal vibrations according to the ISO 10816-3 and VDI 2056-3 standards. ISO 7913-3 and VDI 2059-3 [5] contain a shaft vibration evaluation at orthogonal planes These standards are used to find the monitor vibration levels and assess the status of the turbomachinery in service. It is very important to study the longitudinal vibrations for turbomachinery coupled with induction motors having with skew rotor bars. Thomson [6] studied the induction motor failures correlating the air gap eccentricity for radial vibrations. Thereby, the manuscript was considered for turbomachinery coupled with the induction motor in sour gas service and had severe vibrations while operations
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