Patent ID: 6926516

Claim:
A combustion method comprising steps of: forming combustion air so as to have a jet flow cross section in an air throat, having a larger specific surface area than that in a case of supplying from a circular throat the same quantity of combustion air as said combustion air has; injecting said combustion air into a furnace; injecting fuel toward a jet flow of said air for causing a jet flow of said fuel to be rapidly mixed with said air jet flow with strong turbulence before losing velocity energy of said fuel jet flow; wherein said combustion air is supplied after being preheated to have a high temperature close to a temperature of combustion exhaust gas by collecting heat of said combustion exhaust gas exhausted from a regenerative medium; and wherein said combustion air whose quantity is less than a theoretical air quantity is supplied and high-temperature air combustion for forming a non-oxidizing atmosphere or a reduction atmosphere is carried out; and said fuel is injected with a ratio de/Dpcd of a corresponding diameter de of an opening ( 13 a ) of said air throat ( 13 ) and a gap ½ Dpcd from a center of said air throat to a center of said fuel nozzle ( 11 ) falling within a range of 0.1 to 0.5 and with a ratio La/de of said corresponding diameter de of said air throat relative to a distance La from an intersection of a fuel injection axis and a plane on a central axis in a longitudinal direction of said air throat to an outlet surface of said air throat falling within a range of 1.0 to 5.0.