Experimental study on flow and combustion characteristic of a novel swirling burner based on dual register structure for pulverized coal combustion

A novel spout structure which contains dual-gear rings (DGR) and double conical flaring (DCF) for swirling burner is proposed. Flow field outside the novel burner (DGR-DCF burner) is studied in an unconfined environment comparing with a conventional one. The effects of DGR and DCF structures, secondary air distribution and swirling intensity on reverse flow and turbulence are discussed. Results suggest that the novel burner stabilizes reverse flow and enhances turbulence of the flow field under different air distributions and swirling intensities. The novel burner is further studied in a wall-fired pilot furnace. Gas temperature distribution, NOx emission and unburned carbon in the fly ash are researched. Higher ignition temperature near the burner spout and a more stable temperature field in the furnace is formed with the novel burner. Reduction of NOx emission and unburned carbon in the fly ash are achieved. The momentum ratio (M) of inner secondary air to outer primary air is defined to uniform the secondary air distribution. Increase of M raises the temperature level near the burner spout. NOx emission and the unburned carbon in the fly ash both attain their minimum with M = 4.428 in the experiment range.