THE EFFECT OF THE NEAR BURNER AERODYNAMICS ON POLLUTION, STABILITY AND COMBUSTION IN A PF-FIRED FURNACE

An investigation into the effect of a change in the near burner region aerodynamics was undertaken in a large-scale laboratory furnace firin g a high-volatile bituminous pulverised fuel. To this end two variatio ns of primary air/fuel jet design were installed in a swirl stabilized burner of the type used in wall-fired boilers. Significant difference s in flame shape, intensity, stability performance and pollutant emiss ions were observed and recorded when a burner gun with a single annula r fuel injection orifice (SAO), appropriate to industrial practice, wh erein the central bluff body provides a location for the light-up burn er, was replaced with a simplified version with the bluff body removed . The replacement, with a single central orifice (SCO), maintained the same cross-sectional area to that of the original. A dramatic reducti on in NO emissions (30%) was observed for this burner with no discerni ble deterioration in flame efficiency brought about by a reduction in particle burnout. Under normal operating conditions the SCO burner exh ibits a similar stability performance to that of the SAO.