Solid fuel burner, solid fuel burner combustion method, combustion apparatus and combustion apparatus operation method

Abstract

A solid fuel burner and its combustion method suited for encouraging fuel ignition and avoiding slugging caused by combustion ash, wherein a gas of low oxygen concentration (exhaust combustion gas) is used as a carrier gas of such a low grade solid fuel as brown coal. An additional air nozzle for jetting additional air having a velocity component in the circumferential direction of a fuel nozzle is provided in the fuel nozzle, thereby encouraging mixing between the fuel and air in the fuel nozzle. Further, the amount of air supplied from the additional air nozzle is adjusted in response to the difference in combustion loads. Under light load, the amount of air supplied from the additional air nozzle is increased so as to increase the oxygen concentration of the circulating flow formed downstream of the outside of the outlet of the fuel nozzle, whereby stable combustion is ensured. Under heavy load, by contrast, the amount of air supplied from the additional air nozzle is decreased, and a flame is formed away from the fuel nozzle in such a way that burner structures and furnace wall will be less subjected to radiant heat.

1 . (canceled) 
     
     
         2 . A solid fuel burner comprising:
 a fuel nozzle for jetting a fluid mixture of a solid fuel and its carrier gas that has an oxygen concentration lower than air into a furnace;   at least one nozzle, arranged outside the fuel nozzle, for jetting a combustion gas; and   a flame holder provided at a tip end of a partition separating said fuel nozzle and said at least one nozzle, said flame holder serving as an impediment to a mixture fluid flowing in said fuel nozzle and a combustion gas flowing in said at least one nozzle;   wherein at least one additional nozzle for jetting a combustion gas having a velocity component in the circumferential direction of said fuel nozzle is provided in such a way as to project into said fuel nozzle from the partition of said fuel nozzle toward a solid fuel burner center axis, said at least one additional nozzle being placed, in the flow path of the fluid mixture as it flows through said fuel nozzle, at a constant cross sectional portion of said flow path upstream of said flame holder;   wherein a partition of said at least one additional nozzle has a configuration to smoothly reduce the sectional area of the flow path of the fluid mixture and smoothly extend the flow path at a downstream side of the flow path portion with the reduced sectional area;   wherein at least one outlet of said at least one additional nozzle is placed on a side of the partition of said at least one additional nozzle; and   wherein the fluid mixture and the combustion gas are jetted from said fuel nozzle after mixing of the fluid mixture and the combustion gas, and the fuel is burnt after jetting of the fuel from said fuel nozzle.   
     
     
         3 . A combustion apparatus having a solid fuel burner, said solid fuel burner comprising:
 a fuel nozzle for jetting a fluid mixture of a solid fuel and its carrier gas that has an oxygen concentration lower than air into a furnace;   at least one nozzle, arranged outside the fuel nozzle, for jetting a combustion gas; and   a flame holder provided at a tip end of a partition separating said fuel nozzle and said at least one nozzle, said flame holder serving as an impediment to a mixture fluid flowing in said fuel nozzle and a combustion gas flowing in said at least one nozzle;   wherein at least one additional nozzle for jetting a combustion gas having a velocity component in the circumferential direction of said fuel nozzle is provided in such a way as to project into said fuel nozzle from the partition of said fuel nozzle toward a solid fuel burner center axis, said at least one additional nozzle being placed, in the flow path of the fluid mixture as it flows through said fuel nozzle, at a constant cross sectional portion of said flow path upstream of said flame holder;   wherein a partition of said at least one additional nozzle has a configuration to smoothly reduce the sectional area of the flow path of the fluid mixture and smoothly extend the flow path at a downstream side of the flow path portion with the reduced sectional area;   wherein at least one outlet of said at least one additional nozzle is placed on a side of the partition of said at least one additional nozzle; and   wherein the fluid mixture and the combustion gas are jetted from said fuel nozzle after mixing of the fluid mixture and the combustion gas, and the fuel is burnt after jetting of the fuel from said fuel nozzle.