Abstract: A method and apparatus for combusting black liquor generated by semi-chemical and other pulping processes, using a draft airflow furnace such as a rotating kiln, and a lower end mixing nozzle for black liquor and combustion air. A combustion agent is added to the black liquor to support ignition and permit a closely controllable combustion plume or flame adjacent the nozzle. Resulting combustion is complete and well below government environmental air emission standards. Chemical recovery is efficient, clean, and free from products of incomplete combustion.

Abstract: Pulverized coal and air flowing-in a coal nozzle are distributed for combustion with low NOX generation by a concentric central duct with long exterior spiraling vanes which extend upstream and attach to a support pipe extending further upstream in the nozzle. The space from the downstream end of the support pipe to the upstream end of the central duct, and the cross section of the pipe relative to the cross section of the central duct regulate the entry of coal and air into the central duct from which the flow emerges with reduced velocity as a central stream stabilizing the flame. The central duct also has an exterior short vane attached to each long vane to separate the pulverized fuel and air outerflow into fuel-enriched swirling streams and fuel-depleted recirculation zones.