Oxide Layer Rumpling Control Technology for High Efficiency of Eco-Friendly Combined-Cycle Power Generation System

Abstract

Combined-cycle power generation is a high-efficiency power generation method using natural gas that can reduce the emissions of carbon dioxide and other harmful substances by increasing the power generation efficiency. Therefore, the turbine inlet temperature should be increased to improve the power generation efficiency. However, given that the operating environment becomes extreme as the turbine inlet temperature increases, ensuring the sufficient durability of the gas turbine components is a necessity. Thermal barrier coatings (TBCs) applied to ensure the durability of the gas turbine components in a high temperature environment can peel off by stress generated through the difference in the thermal expansion coefficient of each layer. Because internal gas turbine components are damaged if peeling occurs, it is essential to ensure sufficient durability of the TBC. In particular, to enhance the efficiency of the combined-cycle power plant, and to withstand higher operating temperatures, it is essential to develop a TBC with an improved durability performance, when compared with currently commercialized TBCs. In this study, we attempted to improve the durability of the TBCs by mitigating the stress concentration phenomenon by gently controlling the rumpling of the oxide layer. For this purpose, the vertical crack design conditions required to reduce the buckling stress were derived through a finite element analysis. Isothermal degradation and thermal fatigue tests were conducted on the fabricated specimens to verify whether the oxide layer rumpling of the designed TBC was controlled gently and whether the durability was improved. Base on the results, a TBC structure with improved durability using oxide layer rumpling control technology is proposed.