RISK BASED APPROACH TO ASSESS TECHNO ECONOMIC FEASIBILITY OF GAS TURBINE COMPONENT LIFE EXTENSION

Growing demand for flexibility and high maintenance costs make gas turbine systems increasingly expensive. Reliability and availability are both key factors and have a direct impact on the economics of these systems. The plants operators require fast and reliable methods to assess the remaining lifetime of the gas turbine components. Nowadays, inspection and replacement intervals for gas turbine components are typically determined by model based assessment of equivalent operating hours (EOH). However, this method requires a lengthy and expensive process, which needs to be repeated in case of components upgrades. The innovative method proposed in this work collects a considerable number of operational data on different types of machines (ranging from small engines to heavy duty), through which it is possible to build a curve representing the probability of failure. The curve can be updated at each inspection by assessing the presence of damage mechanisms from time to time (implementing data driven procedures for monitoring, diagnosis, and advanced prognosis). The result will be an updated risk curve that provides operators with information about the health status of the components and the potential risk associated to late replacement. Integrating the model developed with the costs associated to maintenance, a comparative cost analysis is carried out to support the decision making process and evaluate the possible benefits. It is clear that a risk based approach (based on statistical data analysis) is easier to use, less costly than a modelling approach and can result in significant economic benefits