Field experience with the sequential combustion system of the GT 24 / GT 26 gas turbine family

he sequential combustion cycle used by the GT24/GT26 family is a reheat process with two combustors which allows increased gas turbine output at high efficiency. Whereas the first combustor is based on proven EV-combustor technology, the lean premixed, self-igniting second combustor is the outcome of an extensive research and development programme. The first GT24 to be operated commercially is installed at the Gilbert station of Jersey Central Power and Light (JCP&L) in the USA [1]. The first GT26 was installed and operated at the ABB gas turbine test center in Birr, Switzerland, the first commercial unit of this type having been ignited in the Rheinhafen power station at Karlsruhe, Germany [2]. GT24/GT26 performance data Rated at 265 MW, the GT26 delivers about 50% more output than a conventional GT13E2 from essentially the same footprint. The higher output is the result of an increase in cycle pressure ratio and the sequential combustion cycle. Additionally, the exhaust temperature of the GT24/GT26 is about 610 °C (1130 °F) over the wide range of 50 to 100 % unit load, which is ideal for combined cycle (gas and steam turbine plant) operation. The power density of the GT24/GT26 gas turbine family is approximately 20 % higher than for other units in this class. GT24/GT26 units feature a more compact design, shorter blade lengths, lower tip speeds and therefore lower stresses, leading to higher reliability.