The present invention provides a fuel feeding apparatus and method for improving the
controllability of mixing process and
mixing ratio of fuel and
combustion air, and a
combustion system and method for effecting new
combustion properties. The fuel feeding apparatus of the
combustion system has fuel feeding means, combustion gas extraction means, steam supply means, mixing means and
fuel gas introduction means. The combustion gas extraction means extracts combustion gas of a combustion area therefrom. The mixing means mixes the fuel of fuel feeding means with at least one of combustion gas extracted from the furnace and steam of a steam generator. The
fuel gas introduction means introduces a mixed fluid of combustion gas, steam and fuel to the combustion area as a
fuel gas, and allows the fuel gas to be mixed with the combustion air. A step of mixing the fuel with the combustion gas after extracted from the furnace and a step of mixing the fuel gas with the combustion air are stepwisely carried out, so that the
controllability of mixing process and ratio of the air and fuel is improved. Such a control of fuel gas flow enables control of characteristics of
flame and production of
flame with new properties in the combustion area.