GE has introduced two new upgrade options for existing 7F (60 Hz) gas turbines: the DLN 2.6+ combustion system; and what it calls Advanced Compressor technology.
One benefit of DLN 2.6+ combustor technology, already well established, with over 1.5 million operating hours amassed in the 50 Hz 9F fleet, is increased fuel flexibility, allowing 7F operators to burn up to 25% ethane or propane from shale gas, for example. "Plants operating with this technology have more options to purchase fuel based on composition, as well as price, to help them save on fuel costs", says GE. DLN 2.6+ also gives the option to burn up to 20% hydrogen. And all three fuel sources can be used while at the same time maintaining low emissions.
For existing 7F plants using natural gas the DLN 2.6+ upgrade enables NOx emissions to be reduced by as much as 40% and to "operate as low as sub 5 ppm NOx", says GE. The DLN 2.6+ combustor upgrade, when combined with the already-introduced Advanced Gas Path upgrade can also allow units to operate continuously for "industry-leading" durations of up to 32 000 hours or 1250 starts between required maintenance intervals.
Customers can also "blend" DLN 2.6+ technology with GE's model-based OpFlex control software to further reduce both emissions and fuel costs. For example, by complementing DLN 2.6+ with OpFlex Turndown software, a 7F.04 gas turbine operator running at minimum load for 500 hours per year can reduce their CO2 emissions by 3800 metric tons annually, says GE, while at the same time this hardware-software combination, operating under the same conditions, can save over $300 000 a year in fuel costs at an average natural gas price of $4 per MMBTU.
The first order for the 7F DLN 2.6+ upgrade has been placed by a US power plant in the Midwest, GE reports. It will be installed on two units in Spring 2016.
This project will also include the Advanced Gas Path upgrade. The order marks 54 AGP upgrades sold in 2014 and the 127th sold since 2012, GE notes.
While new as an upgrade option, the Advanced Compressor upgrade derives from technology already deployed in GE's new 7F.05 (formerly 7FA.05) gas turbine, and features 3-D aero airfoils, variable stator vanes, field-replaceable blades, and a reduced number of stages, down to 14, for better durability and lower maintenance costs. It is also the compressor technology employed in the new HA gas turbine and has been subject to extensive validation testing at Greenville, one aim being to fully take on board lessons from previous GE F class compressor integrity issues.
According to GE, the Advanced Compressor upgrade will enable operators "to increase output by as much as 12% while improving operational efficiency up to 2%", allowing them to "capture new revenue streams, as well as deliver more power during peak periods." The performance boost can be fully achieved once installed or expanded over time as surrounding plant assets are upgraded or replaced, says GE.
The new compressor technology also helps operators reduce their outage frequencies and time required for maintenance, with advancements including field replaceable compressor blades and improved borescope access.