High-resolution analysis and research on metal temperature of supercritical steam turbines

Abstract

Aiming at the problem of abnormally high metal temperatures of the low-pressure rotor bearings (#6 and #7) of a 1000MW supercritical steam turbine (N1000-25.0/600/600 type) during low-load operation, this paper systematically analyzes the key factors causing the temperature rise in combination with the working principle of the bearings, the characteristics of the lubricating oil flow field and the actual operating conditions. Research shows that, apart from the conventional issues such as oil quality, oil temperature and load distribution, insufficient oil intake in the bearing area and limited self-aligning capacity of the bearing spherical surface are the main factors. Based on this, a comprehensive maintenance process was innovatively proposed and implemented, including optimizing the structure of the oil inlet wedge to increase the oil supply in the bearing area, precisely adjusting the bearing elevation and clearance, and improving the self-positioning flexibility of the spherical surface. The application effect shows that this scheme has significantly improved the unit’s operation. It provides practical experience with promotion value for solving the common problem of bearing over-temperature in similar units.