Avtomobilʹnyj Transport (Harʹkov) (Jun 2020)
Simulation of a turbine case vibrations for the analysis of transition process
Abstract
Problem. The problem of issues of increased vibration for the case sheets of the steam turbines with the capacity of more than 500 МW was considered. For this work it was found that the main cause of increased vibration in turbine-type steam equipment is forces due to imbalances of the rotors, as well as the lack of rigidity among the elements of the system. The case from the real practice of operation of power equipment is considered, where the work on the centering of the rotor equipment did not provide significant changes to improve the values of the operating parameters. Goal. The objectives of this work were to model the parts and the entire system of turbine-foundation-base for the turbine K-500-65 / 3000 HTGZ, its levels of forced oscillations, as well as to perform research on the causes of increased vibration in low-pressure cylinder housings for the analysis of the transient process. Methodology. For this research the methods of finite elements and oscillations were used, as well as the measures developed by the author and methods for building models and studies of oscillations in the system turbine unit-foundation-base. Result. As a result of the conducted researches the following were obtained: finite-element three-dimensional model for the system of turbine unit-foundation-base, dependence of amplitudes on frequencies for the system of points in the cases of low-pressure cylinders. These studies have led to conclusions about the reason for the possible increase in the level of vibration in the upper parts of the steam turbine housings. Originality. The types of three-dimensional models of the parts and the whole turbine unit-foundation-base system developed by the author are unique. Due to the special approach to the development of models, it becomes a real opportunity to conduct a study of vibration characteristics at another structural level, which allows the analysis of vibration levels of all elements of this system. Some types of research require some changes in the specification of the part of the system that requires further analysis. This allows you to perform calculations using the finite element method in modeling the system unit-foundation-base with a significant specification of the actual conditioned modes of operation. Third-party teams of specialists in the study of systems of the specified type using the methods common among them did not solve the problem and clarify the specific conditions for the causes of increased vibration among the parts of the hulls of the steam turbine unit. Practical use. The practical application of the results of the study is essential as an illustration of emergency avoidance and marching development for specialized models in the study of the oscillation characteristics of the turbine unit-foundation-base, as well as a typical solution of classical problems to analyze the possibility of emergencies in the systems operated and at their designing. The results of the work are proposed for use in relation to a set of actions to increase the rigidity of the hull parts and general equipment of steam turbine plants and prevent accidents that could lead to the final decommissioning of equipment without the possibility of restoring the entire system operating mode.
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