Investigation of oscillations of the case of steam turbine with a capacity of 500 MW

Abstract

Problem. The problem of increased vibration of bodies of a steam turbine with a capacity of 500 MW is considered. The main cause of the increased vibration of the steam turbine is the rotor's unbalance and insufficient stiffness of the system elements. The case of operating practice is considered, where the rotational alignment did not significantly change the vibration parameters. Goal. The purpose of this work was to simulate the forced oscillations of the bodies of low-pressure cylinders in the turbine-foundation-base system with a turbine K-500-65 / 3000 KHTZ, as well as to study the causes of their increased vibration. Methodology. The research was carried out using the method of oscillation, the method of finite elements, as well as author's methods of constructing models and conducting research on oscillations of the turbine-foundation-base system. Results. As a result of the research, a three-dimensional finite-element model of the turbine-foundation-base system was obtained, and the amplitude-frequency dependences for the points of the cylinder body of low pressure were obtained. The conducted study made it possible to draw conclusions about the causes of increased vibration of the upper parts of the bodies of the steam turbine. Originality. The type of developed three-dimensional models of the turbine-foundation-base system is unique. Due to the features of this model, it is possible to study vibration processes at a level that allows you to analyze the vibrations of complex elements of the system. For individual studies, further specification of the individual parts of the system is required. This allows us to use the features of the finite element method to specify the turbine-foundation-base system in accordance with the actual operating conditions. By other researchers, using other methods and approaches, the problem was not solved and the causes of the hanging vibration of the cylinder body of low pressure were clarified. Practical value. The practical significance of the work performed is an illustrative tool for the development of specialized models for investigating forced oscillations of the turbine-foundation-base system, as well as solving a practical problem in analyzing the causes of increased vibration of individual complex elements. The results of the work were used to develop measures to improve the vibration state of power units with steam turbines of 500 MW capacity.