Assessment of steam turbine performance degradation in long-term operation

Sustainable Development Goal 7 is about affordable and clean energy for all. The push for decarbonization, with most countries aiming to reach net zero by 2050, will lead to the decommission-ing of many fossil fuel power plants. These plants are complex and costly to build, making repurposing a viable alternative. As a result, studies are exploring ways to convert them to operate on alternative fuels. The steam turbine is one of the most expensive components in a power plant. Over time, prolonged operation can lead to a decline in its efficiency. In order to be used further, the extent of efficiency loss must be assessed, which represents the purpose of the study. The results indicate that power loss ranges from 2.03 % for the 210 MW turbine to 7.51 % for the 150 MW turbine. The analysis of isentropic efficiency of the high pressure, reheat and low-pressure turbine revealed that actual working conditions have an important impact on overall efficiency and pow-er output of the turbine, maybe even more than long-term operation. The power loss can be considered moderate, and anytime it is technically possible, repurposing the steam turbine should be taken into account. • Efficiency loss of steam turbines was analyzed over a period of several decades. • For improved relevance of results, two types of steam turbines were studied. • Power loss can be considered moderate, as it was found between 2.03 % and 7.51 %. • Actual working conditions also have an important impact on overall efficiency. • When possible, repurposing the steam turbine should be taken into account.