Premixed combustion on ceramic foam burners

Abstract Combustion of a lean premixed methane–air mixture stabilized on a ceramic foam burner has been studied. The stabilization of the flame in the radiant mode has been simulated using a one-dimensional numerical model for a burner stabilized flat-flame, taking into account the heat transfer between the gas and the burner and the radiative properties of the ceramic material. The combustion has been modeled with the skeletal mechanism and the nitrogen chemistry using an accurate postprocessing technique based on the reaction mechanism of Glarborg et al. [16] . It is shown that the flue gas temperature is decreased significantly in the radiant mode. The emissions of CO and NO are therefore considerably lower compared to combustion in the blue-flame mode. The numerical results are validated with experiments. The temperature of the flue gases and the surface are measured in combination with the concentrations of the pollutants CO and NO. The temperatures have been obtained with nonintrusive techniques. Coherent anti-Stokes Raman scattering (CARS) has been used for the gas temperature and infrared pyrometry for the surface temperature measurements. Gas samples have been obtained with a suction probe and analyzed further by an infrared absorption technique (CO) and by a chemiluminescence analyzer (NO). From a comparison of the experimental and computational results it is concluded that the ceramic burner is chemically inert, since the results are similar to those for water cooled flat-flame burners. It is shown that modeling of the gas radiation is essential for an accurate prediction of CO in the postflame zone. Furthermore, it is shown that prompt NO, as well as the thermal NO, mechanisms are important for an accurate prediction of the total NO emission for combustion in the radiant mode.