PULVERIZED COAL BURNER, PULVERIZED COAL BOILER AND METHOD OF BURNING PULVERIZED COAL

摘要

The present invention is directed to a burner for pulverized coal. The burner has a coal duct for pulverized coal and primary combustion air and a secondary combustion air duct such that the coal, primary air and secondary air mix outside the outlet nozzles of the duct in a mixing zone where combustion occurs. Coal distribution means in the coal duct create, adjacent the outlet nozzle, at least one outer zone of flow spaced from the coal duct axis and at least one inner zone of flow nearer the coal duct axis. These are means for decreasing flow in the outer zone relative to the flow in the inner zone, prior to entering the mixing zone. To achieve good mixing, and promote NOx reduction, the coal concentration in the outer zone is higher than in the inner zone.