Problems of ensuring vibration reliability of power equipment

Abstract

The article discusses general issues related to ensuring vibration reliability of steam turbines, various factors that can cause increased vibration of turbine units, including design, technological, and operational factors. Special interest is given to hidden factors that can be detected only indirectly through analytical methods by studying the complex “turbine unit – foundation – base” (TFB) system. For example, increased stresses in the structure and, accordingly, zones of probable crack development due to seismic subsidence of supports or high vibrations can be detected. Such defects can be the subject of study in so-called predictive analytics. It is shown that ensuring vibration reliability requires a systematic approach. Among the many causes of vibration, it is always necessary to identify the most significant primary causes. Requirements for ensuring reliability at different stages of the creation and operation of a turbine unit are formulated. A stability diagram of the turbine unit is provided, where the stability boundaries are presented for the first time as functions of the main parameter of the working fluid flow through the turbine unit. It is shown that the foundation requirements in RD 34 15.078-91 are outdated and do not meet modern reliability standards for turbine units. The main defects in the assembly of the shaft line are listed, and the primary requirements for the assembly of rotors in half-couplings are formulated. The need for machining bearing liners to create a cylindrical boring surface is emphasized, and scraping the surface for this purpose is not recommended. For the first time, the need for grinding the ends of half-couplings after their deformation due to bolt tightening to half the yield strength is indicated. This is important because residual deformations are detected at the ends of the half-couplings, which hinder the quality of the half-coupling fit.