Steam Turbines operating in Concentrated Solar Plants (CSP) are subjected to daily thermal stress peaks induced by start-ups and load variations deeply affecting allowed production per day. The extent and number of such thermal stresses is largely depending on both weather conditions and the capability, of both plant and operators, to smooth the steam temperature and load variations. In this operating scenario, conservative simplified rules are normally applied to determine daily warm-up times duration at starts, to preserve critical components from Low Cycle Fatigue damage, and the planned maintenance intervals have been typically defined on the basis of a specified number of starts and running hours.

In this article, the application of an online Rotor Stress Monitoring (RSM) technology, installed in the Steam Turbine User Control Panel, is used to directly determine the fatigue damage cumulated by each Start-Up and load variation. The results of application of this technology, with respect to standard formulations, are shown for a specific Concentrated Solar Plant across an operating period of four years. It is shown how, using the RSM as a basis for either start-up or maintenance scheduling, can result in optimization of start-up times and maintenance intervals.

The applicability of rotor stress direct monitoring and life analysis to higher temperature services is also discussed, either for CSP, Combined Cycles or other.


Operation and Maintenance Improvements of Steam Turbines Subject to Frequent Start by Rotor Stress Monitoring

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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