Modeling and analysis of 500 MW turbine casing oscillations near basic vertical oscillation

Abstract

The problem of increased vibration of the most flexible housings of a steam turbine of a power unit of 500 MW is considered. The main cause of the increased vibration of the steam turbine is the unbalance of the rotor and insufficient rigidity of the elements of the system. A case study is considered where the centering of the rotors did not significantly change the vibration parameters. The purpose of this work was to simulate the forced oscillations of low pressure cylinder housings in a turbine-foundation system with a turbine capacity of 500 MW, and to investigate the causes of their increased vibration. The studies were carried out using the oscillation method, the finite element method, as well as the methods developed by the author to construct models and conduct oscillation studies of the turbine-foundation system. As a result of the studies, a three-dimensional finite element model of the turbine-foundation-base system was obtained. The amplitude-frequency dependences for the points of the low-pressure cylinder housings were obtained. The conducted research made it possible to draw conclusions about the causes of increased vibration of the rotors of the steam turbine. The type of developed three-dimensional models of the tour-bin-foundation-base system is unique. Due to the features of this model, it is possible to study the vibrational processes at the level, which allows you to analyze the vibrations of almost all elements of the system. For individual studies, further specification of the parts of the system important for the task is needed. The study made it possible to conclude on the causes of increased vibration of the upper parts of the steam turbine housings. Due to the unique features of the developed model, it is possible to study vibration processes at a level that allows you to analyze the vibrations of complex elements of the system. The practical value of the work carried out is a clear tool for the development of specialized models for the investigation of the forced oscillations of the turbine-foundation-base system, as well as the solution of a practical problem to analyze the causes of increased vibration of individual complex systems of the elements. The results of the realized work were used to develop measures to improve the vibration state and reability of power units with steam turbines with a capacity of 500 MW.