Performance and Flexibility of the DLN 2.6e Combustion System on the 7HA.03 Gas Turbine

Abstract At GE Vernova, the newest advanced dry-low NOx (DLN) combustion system for HA gas turbines is the DLN 2.6e. After describing the key enabling features of the DLN 2.6e, this paper focuses on the emissions performance and operational flexibility of the combustion system on the 7HA.03, currently GE Vernova’s most efficient gas turbine in the 60 Hz electric power generation segment. While some full-scale, single-can lab results are presented, the primary focus of this manuscript is the performance on natural gas fuel from the testing of three 7HA.03 gas turbines, one at the GE Vernova full-load test stand and two at a commercial generating facility. The DLN 2.6e is a can-annular, lean premixed combustion system. The advanced premixer at the head end efficiently mixes fuel and air in straight tubes, which are arranged in three fueling circuits. Additionally, the DLN 2.6e system has four axial fuel staging injectors located in the downstream half of the combustion liner, split into two fueling circuits. At high load, the axial fuel stage creates a secondary combustion zone with a substantial fraction of the total energy release and with a low residence time to the combustor exit plane. These features, along with the efficient premixing at the head end, enable the system to achieve below 25 ppm NOx at 15% O2 at the high firing temperatures of the 7HA.03. From full load, the combustor exit temperature may be lowered to attain 5 ppm NOx at 15% O2 before lean blow out occurs. At low loads, the fuel flow to one of the two axial fuel stage circuits may be eliminated, enabling the system to achieve less than 25 ppm NOx at 15% O2 and 9 ppm CO emissions down to near 15 percent of gas turbine full load. 7HA.03 engine data is presented showing low combustion dynamics and little change to emissions when running with cold fuel, representing a 22 percent increase in modified Wobbe index compared to the heated fuel design point. The combustion and control systems support accelerated load ramping. A 7HA.03 gas turbine was demonstrated to progress from ignition to full load in around ten minutes. Finally, the DLN 2.6e has been demonstrated in lab testing to be operable with up to 50% hydrogen by volume in the fuel, and an associated increase in NOx emissions was observed.