Abstract: A pulverized fuel firing apparatus comprises a first pulverized fuel injection compartment so constructed that the combined amount of primary air and secondary air to be consumed is less than the theoretical amount of air required for the combustion of the pulverized fuel to be fed as mixed with the primary air to a furnace, a second pulverized fuel injection compartment so constructed that the combined primary and secondary air amount is substantially equal to the theoretical air for the pulverized fuel to be fed together with the primary air, and a supplementary air compartment for injecting supplementary air into the furnace. The three compartments are arranged close to one another and control the NOx production upon combustion of the pulverized fuel.

Abstract: A method of burning fuel with lowered emission of nitrogen oxides comprises feeding pulverized fuel to the main burner in a combustion furnace and additionally feeding pulverized fuel to the region of the furnace where the first fuel is about to conclude its combustion, using inert gas with or without a low oxygen content as a conveying fluid, while supplying oxygen or air to a region downstream of the region for fuel addition.

Abstract: A burner includes a plurality of air nozzles open toward a furnace and which are disposed unsymmetrically with respect to the central axis of the burner and so combined that the velocity of combustion air to issue from one or more of the nozzles is higher than the mean air velocity through the total air nozzle opening area and the velocity of combustion air from the rest of the nozzles is lower than the mean velocity. The opening area of the lower-velocity air nozzle or nozzles accounts for from 30 to 60% of the total opening area. A fuel nozzle or nozzles are located within or adjacent the lower-velocity air nozzle or nozzles. The amount of air to issue from the lower-velocity air nozzle or nozzles is not more than 70% of the theoretical air for the fuel to jet out of the burner.

Abstract: A fuel combustion apparatus for burning a premix of an air stream and a fuel jet, comprising an air nozzle for issuing air to form a conically spread film of the air stream, and an atomizer for injecting fuel circumferentially unevenly into the conical film of air stream so that a premix uniformly mixed with air but having a circumferentially varied air-fuel ratio which is locally selectively greater than 1 or less than 1.

Abstract: Method and burner apparatus for burning fuels wherein an air-fuel premixture of a low fuel concentration formed by premixing a fuel with combustion air in an amount larger than the theoretical air amount necessary for combustion of said fuel is fed and burnt in a combustion zone, and simultaneously, a fuel and combustion air in an amount smaller than the theoretical air amount necessary for combustion of said fuel are fed separately and burnt in the vicinity of said combustion zone or an air-fuel premixture formed by premixing a fuel with a part of combustion air supplied in said amount and the remainder of said combustion air are fed separately in the vicinity of said combustion zone.