POWER-GEN Europe and REWE 2017

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Gas Turbine Cooling Evolution / Enhanced Air Cooling (Room Rheinsaal 4)

Mitsubishi Hitachi Power Systems (MHPS) has traditionally targeted high Turbine Inlet Temperatures (TiT) as an effective way to increase the efficiency of Advanced Class Gas Turbines (ACGT) and the corresponding combined cycles. This strategy led MHPS to pioneer the application of steam cooling in 1997, resulting in a large and successful steam cooled fleet featuring close to ninety units in Asia and North America. MHPS latest large frame gas turbine design targets high efficiency and low NOx emissions by applying a modified air cooling approach called “enhanced air cooling”. This new design is based on extraction and cooling of a small fraction of the GT compressed air using an external cooler prior to its application to the combustion hardware. A single stage radial boost-up compressor is then used to provide the required cooling air mass flow to the combustion liners. The cooled air is circulated through a jacketed transition piece arrangement, similar to the steam cooled counterpart, and is mixed with the combustion air in a semi-closed configuration, after removing heat from the combustion hardware. This concept is currently being validated at MHPS Long Term Verification plant in Takasago. This paper describes the enhanced air cooling system and presents operational results of the current validation.