Effects of air entry of swirling flameless combustion in a low NOx burner

Abstract

Achieving considerable improvement in the ignition performance via flameless combustion is a big challenge. Obtaining uniform temperature field inside the combustor with ultra-low NOx and CO emission as well as enhanced combustion stability remains a challenge. In the present work, a flameless combustion technique is applied using a laboratory scale furnace under the swirling flameless combustion, using natural gas. Gaseous fuel is injected in the direction of the combustor axis and air is allowed to enter along the tangential and axial direction of the combustor to create swirling flow with recirculation as well as enhanced mixing of the hot gas near the fuel nozzle. The experimental results of temperature and emission of combustion process are presented. Three ratios of axial to tangential air entry were studied. These ratios were 7/3 (Case 1), 1 (Case 2), and 3/7(Case 3). Case2 shows the highest temperature followed by Case 1 and 3. The amount of NOx and CO emission measured at the outlet is observed to be the lowest for Case 3 as a result of the high recirculation and swirling effect.