Experimental study of a staged methane/air burner based on combustion in aporous inert medium

Further decreases in NOx. emissions from burner systems, in particular dome stic heating systems, Stirling engines, gas and steam turbines, and so fort h, are of enormous interest at present. Staged combustion in inert porous m edia offers a high potential to meet the operational and environmental requ irements for those applications. A special experimental facility was built to study the behavior of staged combustion in porous inert media. The const ruction allows investigations of the effects of staging with pure methane o r air by measuring the temperatures in the combustion region. In addition, the emissions of NOx COx and CH4 were measured in the flue gases to establi sh how the thermal heat load, the staged quantity and the air ratio affect them. For certain staged quantities and overall air ratios, the pollutant e missions lie in an optimal range. The results show that the NOx emissions c an be decreased by approximately 30-40% for the same overall air ratio in c omparison with the case without staging. Two different porous media used-an alumina fabric lamella structure and an SiC foam-show that the characteris tics of the pollutant emissions are only slightly dependent on the porous m edium. Another result is that in the staged mode, the combustion can be kep t stable at higher primary air ratios.