Retrofitting of an Industrial DLN Gas Turbine Combustor for Fuel-Flexible Hydrogen Applications

The use of lean-premixed combustion systems in gas turbines for power generation represents one of the most effective options to achieve low NOx emissions under dry conditions. Modern swirl burners can guarantee very low emissions and stable operation when traditional fuels (i.e., methane or natural gas) are used. However, these systems could be affected by flashback and could generate an increase in NOx emissions when they are fed with hydrogen blends. Considering the complexity of these systems and the fact that they are operated close to harmful conditions, it is necessary to schedule a periodic maintenance of the combustor and replacement of the injection system, implying maintenance costs, power plant shutdown, and environmental impact. This work follows a series of already performed studies on the injection system and the combustion chamber for a 5 MW machine. Both the available dataset obtained from reactive numerical simulations and the observations in the grade of deterioration registered during the maintenance phase are used as retrofitting guidelines for the definition of an innovative design of the injector/combustor geometries. The newly designed configuration is numerically tested both at natural gas conditions and in the case of hydrogen blends, thus guaranteeing both stability at different fuel compositions and the extension of the service intervals for the upgraded design.