Abstract: A boiler operating method operates a boiler by switching between air combustion mode and oxygen combustion mode when burning fossil fuel with first combustion gas and second combustion gas. The second combustion gas compensates for oxygen deficiency in the first combustion gas. The air combustion mode uses air as the first combustion gas and the second combustion gas while the oxygen combustion mode uses mixed gas of combustion flue gas and oxygen-rich gas as the first combustion gas and the second combustion gas, the combustion flue gas being produced when the fossil fuel is burned. By mixing the oxygen-rich gas in the air in the process of switching between air combustion mode and oxygen combustion mode, the air being the first combustion gas used in the air combustion mode, the boiler operating method can switch between the air combustion mode and oxygen combustion mode while maintaining stable combustion.

Abstract: A spray nozzle is provided with upper and lower channels and from respective surfaces, the two channels form a cross shape, and become a fuel spray hole by communication of an intersecting part. A guide member is provided, in contact with the upstream-side channel, in a position overlapped with the intersecting part with respect to the spray direction of the spray nozzle. Spray fluid is branched with the guide member from the fuel fluid duct connected to the spray nozzle, passes through the upstream-side channel, to the intersecting part, and is sprayed. The spray fluid forms opposed flows toward the intersecting part in the upstream-side channel to collide with each other at an obtuse angle of 90° or greater, then is sprayed from the intersecting part, to form a thin fan-shaped liquid film. The liquid film is divided by a shearing force from the peripheral gas, atomized into spray particles.

Abstract: A boiler operating method operates a boiler by switching between air combustion mode and oxygen combustion mode when burning fossil fuel with first combustion gas and second combustion gas. The second combustion gas compensates for oxygen deficiency in the first combustion gas. The air combustion mode uses air as the first combustion gas and the second combustion gas while the oxygen combustion mode uses mixed gas of combustion flue gas and oxygen-rich gas as the first combustion gas and the second combustion gas, the combustion flue gas being produced when the fossil fuel is burned. By mixing the oxygen-rich gas in the air in the process of switching between air combustion mode and oxygen combustion mode, the air being the first combustion gas used in the air combustion mode, the boiler operating method can switch between the air combustion mode and oxygen combustion mode while maintaining stable combustion.