While the hydrogen economy may not be taking off in the way that was once projected, significant work is still being done by the gas turbine OEM’s on modifying combustors to operate on H2, not least GE Vernova. It has recently announced completion of the validation test campaign for a prototype Dry Low NOx (DLN) hydrogen combustor for B- and E-class gas turbines.
The test campaign, conducted at GE Vernova’s Global Technology Center in Greenville, South Carolina, demonstrated successful operation on natural gas and hydrogen blends and on 100% hydrogen with dry emissions below 25ppm NOx. GE Vernova currently plans to make the new DLN system available for new and existing B- and E- gas turbines as early as 2026.
GE Vernova describes itself as a “world leader in gas turbine fuel flexibility”, including over 120 gas turbines that have the capacity to operate on or are currently operating on fuels that contain hydrogen, which have produced more than 530 TWh of electricity over 8.5 million hours. GE Vernova says this recent hydrogen announcement underscores its “continuous commitment to reduce the carbon emissions of its gas turbine generation fleet.”
“Developing a DLN combustion system able to burn 100% hydrogen safely and reliably is an engineering challenge,” says Jeremee Wetherby, Carbon Solution leader, GE Vernova. “One of the ways hydrogen fuel differs from natural gas is that it burns much faster. Its flame speed is roughly eight times higher and presents risk of flashback. Through the test campaign, the GE Vernova team demonstrated very robust operation for the new DLN technology, without flashback across a range of loads and fuel from pure natural gas to 100% hydrogen.”
Combustion dynamics or noise can be a challenge as well with hydrogen operation. The prototype performed very well in that respect, with relatively low levels even when operating on pure hydrogen. Test results also indicate that the technology can deliver availability levels and maintenance intervals comparable to current DLN combustors operating on natural gas. This is of “particular importance for industrial customers who depend on gas turbines to power their operations reliably,” says GE Vernova.
A new micromixer-based fuel air pre-mixer is described as “foundational” to the prototype combustor capability. GE Vernova says its research on micromixer technology started in 2005 as part of collaboration with the US Department of Energy. Micromixer-based fuel premixers have now been part of the product portfolio for over seven years notably on GE Vernova’s H Class gas turbine fleet. Recent research conducted at GE Vernova’s Advanced Research Center in NY and at the Global Technology Center in Greenville, SC, focused on improving micromixer and axial fuel staging for hydrogen capability. This research culminated with the construction of a full size 6B DLN combustor prototype and testing at full scale conditions (pressure, flow, temperature) in the Greenville combustion test facility.
GE Vernova characterises its B- and E-class turbine fleet as “highly robust”, with an installed base of approximately 2800 units around the world “powering industrial processes and operations around the clock.”
Hydrogen combustor options already exist today, with ratings up to 100% hydrogen, however existing combustors use a diluent such as water to manage emissions. The new H2 DLN combustor technology is expected to present several advantages over existing systems:
- elimination of need for water or other diluent;
- increased efficiency: 4 to 7% improvement in combined cycle heat rate;
- improved availability and longer maintenance intervals; and
- reduced NOx emissions.
