Continuing the evolution of its F technology along a route designed to meet demands for higher efficiency and lower life-cycle costs, GE has produced an uprated version of its Frame 6FA gas turbine, a unit for which GE claims 400 000 reliable operating hours. Designated the PG6111FA, the machine is offered with an output increase of 9.2 per cent and a heat rate improvement of 2.7 per cent.
The new unit is rated at 75.9 MW and 35 per cent efficiency in simple-cycle applications. In combined-cycle service, the machine should have an output of 117.7 MW at 54.7 efficiency, a one point improvement. These advances add up to a 2.8 per cent improvement in the cost of electricity generated, say GE. The first uprated unit is scheduled for delivery in mid 2003.
The main factors in improving the performance of the 6FA include a 40 °C increase in firing temperature to 1327 °C, a 3 per cent increase in airflow, and a higher pressure ratio of 15.6, up from 14.6. These enhancements were achieved by incremental scaling of GE’s Frame 7FA gas turbine, thus transferring the design and the operational experience of the Frame 7 machine to the 6FA.
The increase in firing temperature was achieved through improvements in component materials and cooling, and by elevating the pressure ratio. Also critical to the upgrade was the expanded use of film cooling and thermal barrier coating for turbine nozzles and buckets. The unit also features GE’s advanced DLN2.6 NOx control combustion system
