Lifetime Assessment of a Low-Pressure Steam Turbine Blade

This work proposes a multilayer methodology for assessing the lifetime of steam turbine blades based on damage calculation, fracture mechanics considerations, and probabilistic analysis.

The life consumption of steam turbine components is determined through evaluation of steady-state stresses (thermal and centrifugal) and transient stresses. Transient stress analysis is conducted for cold start, warm start, and hot start scenarios, utilizing startup curves derived from available site information and operation manuals. Temperature and stress distributions are determined, followed by life estimation calculations for Creep life damage and fatigue damage using modified Miner and Palmgren’s rule.

Analysis reveals that maximum damage occurs during cold start due to the generation of maximum transient stresses. Critical crack size and time to failure assuming a notch are calculated through fracture mechanics considerations.

The proposed multilayer methodology offers a comprehensive approach to assessing the lifetime of steam turbine blades, integrating damage calculation, fracture mechanics, and probabilistic analysis. This approach enhances understanding of blade performance under various operating conditions and aids in optimizing maintenance strategies for steam turbine systems.