The first GT26 HE upgrade project for GE’s GT26 gas turbine platform was announced earlier this year with customer Uniper in the UK and is expected to go into operation in 2020.
GE just announced a second order, again in the UK, for the Drax’ Shoreham power station near Brighton. This upgrade is expected to be in commercial operation in 2021.
According to GE, the GT26 HE upgrade will increase the combined-cycle efficiency of the power plant by about 2.5% and add about 44 MW of power at baseload. The upgrade package involves innovations in aerodynamics, materials, and combustion dynamics, as well as a significant utilization of additive-manufactured parts. It is a package especially meant for retrofits.
Alex Evans, GE Power’s sales director Europe for the GT26 platform, explained that the HE upgrade is a major revolution in all components of the GT26 gas turbine: “With the exception of the structural components, pretty much everything else is changed.
“The 22-stage compressor in the GT26 – one of the biggest compressors in gas turbines for industrial applications – is being replaced by a completely different aero-type design. From a structural point of view, we are able to keep for example the compressor vane carriers one and two, that hold the first compressor stage. All blades, vanes and other rotating components are being changed.”
The low pressure (LP) turbine side has been completely modified too, using the design from GE’s H-class gas turbines. “The redesign includes the introduction of a download flow to the compressor, which allowed to reach the efficiency increase while keeping the increase in power output relatively low and avoid a major transformation of the power plant lay-out,” said Evans.
The combustion section of the GT26 turbine, with two sequential combustors, is one part of the engine that was not completely modified, bar the introduction of new thermal-barrier coatings on the low-NOX burners. This area though, is where GE made most use of additive-manufactured components. “The front panels that locate the 24 burners in the annular combustors feature a series of thermal dampers to control the low frequency vibration generated by low-NOX combustion; their function is to enable a wider range of more stable combustion operation.
“From a technology point of view, the complexity of the new design of these panels would have been impossible to produce with conventional casting, maintaining at the same time their integrity and strength. Here is where additive manufacturing came into play.” Evans added that the fuel lance that bring gas or oil fuel into the burners is another quite complex component that benefitted of additive manufacturing techniques.
GE published some data regarding the benefits of the GT26 HE upgrade, among which the extension of maintenance intervals up to 32 000 hours and an increase of up to 2% base-load efficiency (potentially bringing an annual fuel saving of up to US$ 4 million).
The Shoreham project includes also GE’s digital solutions for the power plant: GE’s Asset Performance Management (APM) and GE’s Operations Performance Management (OPM). These will increase the plant’s predictive maintenance operations and improve availability, as well as the operational decisions of the operator.
Drax Group is one of UK’s leading electricity providers, operating low-carbon and renewable energy power plants.