Pulverized coal burner, pulverized coal boiler and method of burning pulverized coal

摘要

A burner for pulverized coal has a coal duct for pulverized coal and primary combustion air and a secondary combustion air duct such that the coal and primary air and secondary air mix outside the outlet nozzles of the duct in a mixing zone at which 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 slowing flow in the outer zone relative to the flow in the inner zone, prior to the mixing zone. To achieve good mixing, and promote NO.sub.x reduction, the coal concentration in the outer zone is higher than in the inner zone. The slowing means may be radially inwardly projecting baffles.