A Further Retrofit Upgrade for Alstom's Sequential Combustion GT24 Gas Turbine

摘要

In the mid 1990's, advances in gas turbine technology saw the introduction of Alstom's GT24/GT26 gas turbines with sequential combustion. Today this technology has fully proved itself and today's GT24/GT26 engines show both significant higher performance and more operational features when compared with the first engines. Fleet operating feedback is a significant factor for product updates and the long term changes and upgrades are in line with Alstom's continuous development programs. Traditionally such development programs focus on output and efficiency, but these are not the only drivers. Factors such as operating flexibility and fuel flexibility are also demanded by operators wanting to remain successful in today's power markets. A significant factor in ALSTOM's development program is the GT26 engine at Alstom's Test Power Plant in Switzerland that benefits directly any GT24 upgrade work. The advantage of having an in-house engine connected to the grid allows testing outside normal limits without any commercial, time or power restraints and provides for full validation of upgrades and verification of future technology steps. Prime examples of the success of such validation work are seen in the field experience of two particular programs: a further upgraded compressor and a moderate increase of turbine inlet temperature (TIT) for a GT24 retrofit application. This compressor inlet mass flow upgrade was fully validated in engine testing in the GT26 at the Alstom Test Power Plant in April 2005. The increased inlet temperature was implemented and fully validated, based on test power plant and excellent field experience of the existing blading with addition of Thermal Barrier Coating (TBC) and an optimized cooling of the first turbine stages. This further upgrade maintains the evolutionary step approach for the GT24, and this paper describes these recent developments and explains the performance improvements that result.