Improving ignition and combustion performance through burner retrofit for a supercritical down-fired boiler

摘要

To improve the ignition and combustion performance of a 600MW supercritical down-fired boiler (DFB) equipped with slot burners, some retrofits on the burners and associated concentrators were conducted. Comparative measurements on the performance of concentrators, and temperatures in the zones of burner and hopper were measured before and after the retrofit under different operation settings. Results revealed that before retrofit though in general the fuel-rich coal/air mixture could be ignited within the distance of 2.5m, the ignition of the fuel-lean coal/air flows was poor. For all burners, ignition was postponed with the increasing secondary air. After retrofit, carbon content in fly ash and slag decreased by improving the primary air separation devices, air distribution and nozzle structure design. The ignition distance of the fuel-rich flows and the depth of flame traveling path became remarkably shorter, and flame temperature in the hopper region decreased. The combustion stability and efficiency of the boiler were improved.