CATALYTIC COMBUSTION FOR LOW-NOX H2-FUELLED GT

Catalytic combustion is proposed as a primary mean to control NOx emissions in gas turbine systems fuelled with pure hydrogen or high H2 content fuels. Nevertheless it has been found that hot-spot formation on the catalyst, with solid temperatures largely exceeding the adiabatic flame temperature of the feed mixture, poses serious challenges for materials durability and, in turn, strongly limits the maximum attainable temperature level of the exit gas leaving the catalytic module. In this work several active and passive strategies have been examined either experimentally or by simulations and compared with regards to their ability to reduce catalyst overheating, such as: change of catalyst morphology (cell density), variation of thermal conductivity of the substrate, presence of a diffusional barrier above the active layer, steam addition. Moreover the study has been extended to include fuel rich feed conditions to the catalytic reactor.