An experimental study on a self-recirculation type low NOx tubular flame burner

An experimental study has been made on a 1.25-inch diameter self-recirculation type low NOx tubular flame burner. The burner has eight self-recirculation paths and the extent of burned gas recirculated is varied by changing the number of the recirculation path opened. With use of NOx and CO/CO₂ meters, NOx and CO concentrations at the burner exit have been determined for various numbers of the recirculation path. Results show that with an increase of the number of the recirculation path, the NOx concentration is significantly reduced. When all the eight recirculation paths are opened, the NOx concentration is reduced to 44 ppm, which is about half the value of NOx, 86 ppm, when all the recirculation paths are closed. Thus, it is confirmed that the present, simple device of self-recirculation type tubular flame burner can successfully reduce NOx emission without great cost and space.