Aerosol ignition in iron powder flames stabilized on a new type of jet-in-hot-coflow burner

A novel Jet-in-Hot-Coflow burner for the combustion of solid metallic particles is presented. This system features an electrically preheated coflow to ignite particles without the need for a pilot flame, mimicking exhaust gas recirculation, a method often used in industry to suppress NO${}_x$ emissions and stabilize or control a combustion process. Two different iron powder samples with different particle size distributions were combusted, and their combustion products were analyzed using quantitative XRD to study the effect of particle size and interparticle heating on the ignition temperature of a suspension. It was found that a large fraction of the larger particles failed to ignite, probably due to insufficient heating during the residence time in the hot coflow. An increase in the dust concentration, expected to increase local temperatures and interparticle heating effects, did not significantly decrease the suspension ignition temperature for these powders.