Axial staging in combustor upgrade helps to deliver emission compliance at 25% load

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GE has introduced the new 7F DLN2.6+ Flex upgrade solution at the annual 7F Users Group Annual Conference in Atlanta.

Leveraging GE’s industry-leading DLN 2.6+ combustor and combining it with new Axial Fuel Staging (AFS) technology, the Flex solution is a comprehensive upgrade within GE’s suite of offerings for 7F gas turbines.

The combustor features axial (sequential) staging of combustion in two zones allowing for increased firing temperature at baseload (while maintaining the same NOx level) by operating the later/second stage hotter than the first/primary stage. During low load operation as the gas turbine firing temperature is reduced, percentage fuel split in the staged fuel system can either be reduced significantly or turned off, thereby keeping the overall combustion system into emissions compliance over a wider range of firing temperatures.

It combines several hardware and software technologies into one new flexibility package to help GE’s global 7F fleet customers be more profitable, especially those in high renewable penetration regions like North America and high gas price regions like Asia—as well as those who have aging technology in highly competitive energy markets. The upgrade also will help power producers embrace the flexibility gas technology offers to complement rather than compete with solar and wind.


With a 15 percent lower turndown capability, this technology also gives GE’s 7F customers the flexibility to stay running more frequently while burning less fuel and reducing emissions. This lower load operation can position 7F operators to respond faster to bidding opportunities in regions that experience frequent shifts in grid demand due to renewable power fluctuations. The combination of lowering operating costs and capturing new revenue streams can help GE customers grow profitability through more competitive operating profiles.

Other benefits include:

  • Lower minimum emissions compliant load (MECL), from 40 percent to 25 percent.
  • Reduced fuel burn by 25 percent at new MECL.
  • Faster, lower-emissions starts.
  • Real-time optionality for energy traders.
  • Increased access to ancillary services including spinning reserve and peak power bids.

GE has 28 years of experience in 7F gas turbine technology with more than 50 million hours of fleet operating data and 150 gigawatts of installed across approximately 900 units at 350 sites globally. It introduced its industry-leading DLN 2.6+ technology in 2005.