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’sGT24/GT26 gas turbines with sequential combustion. Today this technology has fully proveditself and today’s GT24/GT26 engines show both significant higher performance and moreoperational features when compared with the first engines.Fleet operating feedback is a significant factor for product updates and the long term changesand upgrades are in line with Alstom’s continuous development programs. Traditionally suchdevelopment 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 operatorswanting to remain successful in today’s power markets.A significant factor in ALSTOM’s development program is the GT26 engine at Alstom’s TestPower Plant in Switzerland that benefits directly any GT24 upgrade work. The advantage ofhaving an in-house engine connected to the grid allows testing outside normal limits withoutany commercial, time or power restraints and provides for full validation of upgrades andverification of future technology steps.Prime examples of the success of such validation work are seen in the field experience of twoparticular programs: a further upgraded compressor and a moderate increase of turbine inlettemperature (TIT) for a GT24 retrofit application. This compressor inlet mass flow upgradewas fully validated in engine testing in the GT26 at the Alstom Test Power Plant in April2005. The increased inlet temperature was implemented and fully validated, based on testpower plant and excellent field experience of the existing blading with addition of ThermalBarrier Coating (TBC) and an optimized cooling of the first turbine stages.This further upgrade maintains the evolutionary step approach for the GT24, and this paperdescribes these recent developments and explains the performance improvements that result.