Advanced Maintenance Technology of Gas Turbine Hot Gas Path Parts

Gas turbine combined cycle power generation now occupies the most important position in thermal power generation for its high thermal efficiency and low environmental impact. Hot gas path parts in these gas turbines used under severe high temperature combustion gas environment have relatively short life spans, and are frequently repaired and replaced with new ones. These parts made of expensive advanced supperalloys having complex internal cooling paths are one of the most contributing factors to the costly maintenance of the turbines.

CRIEPI has been involved in the research and development of maintenance technologies to contribute to the cost reduction on gas turbine maintenance.

Life evaluation method based on computational fluid dynamics and finite element stress analysis has been developed to estimate actual 1100 and 1300 degree C class 1st stage blades (Fig. 1).
Maintenance planning support system which enables users to perform effectively stock managements and to produce parts usage planning has been developed. Using this software, the users can reduce effectively the maintenance cost by optimizing the parts usage, repair and purchase schedule (Fig. 2).
Crack propagation prediction system has been developed to store inspection data and to predict crack propagation life reaching specified acceptable limits based on the trend analysis of crack length data for 1st stage nozzles (Fig. 3).
An instrument to evaluate, in a non-destructive manner, degradation of heat resistance in thermal barrier coatings (TBCs) has been developed. The instrument can be applied to thermal barrier performance of actual combustors (Fig. 4).

Fig. 1 Analytical life assessment procedures

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