Methane-Hydrogen Blends in Micro Gas Turbines: Comparison of Different Combustor Concepts

The paper deals with the analysis of the response of two different types of combustors equipping micro gas turbines, when supplied with methane - hydrogen mixtures. Besides the expected reduction in carbon dioxide production, several problems have to be considered concerning the possible increase in nitric oxide formation and flashback phenomena as well. The two combustors approach the lean-premixed or RQL concept and the study is carried out with a number of CFD simulations based on detailed kinetic schemes and accurate turbulence models. Some preliminary experimental validations support the numerical modelling of the lean-premixed combustor, so encouraging the authors to proceed with the analysis of increasing hydrogen / methane ratios. The RQL type combustor offers, in addition, the possibility of an effective split of the injection into two different streams, with evident benefits in terms of nitric oxides reduction.