Technical Features of the GT26 Gas Turbine to improve the Flexibility of the Combined Cycle System KA26

The flexibility of gas turbine and combined cycle power plants is a key requirement for today's power markets, which means more than just high rates of power change and faster-start-ups also operation at part-and low-load. High part-load efficiency across a wide ambient conditions range is also required in many markets today. Alstom with its GT26 (50 Hz) / GT24 (60 Hz) and the associated combined cycle power plants (KA26/KA24) offers these operational flexibility features as well as flexible operating modes, which provides the plant operators with the ability to choose either to run the plant in performance optimized mode (with highest power and efficiency) or, if able to accept a small performance reduction, to extend the service interval by up to 30%. With the KA26/KA24 'Low Load Operation Capability' feature the plant can be kept fully online at around 20% CCPP load or possibly lower, offering an alternative to either running at higher minimum load points or performing a stop/start cycle, and in-turn offer full on-line spinning reserve with the capability to ramp back up very quickly when needed. Within this paper some of the key technical aspects of the GT26/GT24 is explained, which contribute to these flexibility improvements. It is explained how Inlet Cooling and High Fogging can be used to off-set the performance drop-off at high ambient temperatures, how an air pre-heater can be used to improve base load and part load efficiency and what effect the choice of the flexible operation modes have on performance and service intervals.