초록 ▼

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 je

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.

대표청구항 ▼

What is claimed is: 1. A solid fuel burner comprising: a fuel nozzle for jetting a fluid mixture of a solid fuel and its carrier gas into a furnace; at least one air nozzle, arranged outside the fuel nozzle, for jetting air; and a flame holder provided at a tip end of a partition separating said fu

What is claimed is: 1. A solid fuel burner comprising: a fuel nozzle for jetting a fluid mixture of a solid fuel and its carrier gas into a furnace; at least one air nozzle, arranged outside the fuel nozzle, for jetting air; and a flame holder provided at a tip end of a partition separating said fuel nozzle and said at least one air nozzle, said flame holder serving as an impediment to a mixture fluid flowing in said fuel nozzle and air flowing in said at least one air nozzle; wherein at least one additional air nozzle for jetting additional air 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 air 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 the flame holder; wherein a partition of said at least one additional air 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 air nozzle is placed on a side of the partition of said at least one additional air nozzle; wherein the fluid mixture and the additional air are jetted from said fuel nozzle after mixing of the fluid mixture and the additional air; and wherein the fuel is burnt after jetting of the fuel from said fuel nozzle. 2. The solid fuel burner according to claim 1, wherein an air jet flow jetted into said fuel nozzle from said additional air nozzle has a velocity component in the circumferential direction of a fluid mixture flow flowing in said fuel nozzle. 3. The solid fuel burner according to claim 2, wherein a venturi, configured to smoothly reduce and extend the sectional area of the flow path of said fuel nozzle from the outer periphery, and a concentrator, configured to smoothly reduce and extend the sectional area of the flow path of said fuel nozzle from the inside, are both arranged upstream of said additional air nozzle. 4. The solid fuel burner according to claim 2, wherein said fuel nozzle incorporates therein a separator for separating the flow path, and the outlet of said additional air nozzle overlaps with said separator, when viewed in the direction perpendicular to the burner axis. 5. The solid fuel burner according to claim 2, wherein: a venturi, configured to smoothly reduce and extend the sectional area of the flow path of said fuel nozzle from the outer periphery, and a concentrator, configured to smoothly reduce and extend the sectional area of the flow path of said fuel nozzle from the inside, are both provided upstream of said additional air nozzle; said fuel nozzle incorporates therein a separator for dividing the flow path; and the outlet of said additional air nozzle overlaps with said separator, when viewed in the direction perpendicular to the burner shaft. 6. The solid fuel burner according to claim 5, wherein, of the fuel nozzle flow paths divided by said separator, the flow path on the side where the additional air nozzle is mounted on the tip end upstream of said separator has an area greater than that of the flow path reduced by said concentrator. 7. The solid fuel burner according to claim 2, wherein: a concentrator configured to smoothly reduce and extend the sectional area of the flow path of said fuel nozzle from the inside is provided upstream of said additional air nozzle; said fuel nozzle incorporates therein a separator for dividing the flow path; and the outlet of said additional air nozzle overlaps with said separator, when viewed in the direction perpendicular to the burner shaft. 8. The solid fuel burner according to claim 2, wherein said flame holder discourages the flow of the solid fuel jetting from said fuel nozzle and the carrier gas thereof, and the flow of the air jetting from said at least one air nozzle. 9. The solid fuel burner according to claim 1, wherein said at least one additional air nozzle has a configuration to smoothly reduce and extend the sectional area of the flow path of the fluid mixture flowing through said fuel nozzle, a jet outlet formed on the side for jetting the air having a velocity component in the direction perpendicular to the fluid mixture, and a jet outlet formed at a downstream end for jetting the air having a velocity component in the direction parallel to the fluid mixture flowing through said fuel nozzle. 10. The solid fuel burner according to claim 9, wherein a venturi, configured to smoothly reduce and extend the sectional area of the flow path of said fuel nozzle from the outer periphery, and a concentrator, configured to smoothly reduce and extend the sectional area of the flow path of said fuel nozzle from the inside, are both provided upstream of said additional air nozzle. 11. The solid fuel burner according to claim 9, wherein said fuel nozzle incorporates therein a separator for dividing the flow path, and the outlet of said additional air nozzle overlaps with said separator, when viewed in the direction perpendicular to the burner axis. 12. The solid fuel burner according to claim 9, wherein a venturi, configured to smoothly reduce or extend the sectional area of the flow path of said fuel nozzle from the outer periphery, and a concentrator, configured to smoothly reduce and extend the sectional area of the flow path of said fuel nozzle from the inside, are both provided upstream of said additional air nozzle; said fuel nozzle incorporates therein a separator for dividing the flow path; and the outlet of said additional air nozzle overlaps with said separator, when viewed in the direction perpendicular to the burner shaft. 13. The solid fuel burner according to claim 9, wherein, of the fuel nozzle flow paths divided by said separator, the flow path on the side where the additional air nozzle is mounted on the tip end upstream of said separator has an area greater than that of the flow path reduced by said concentrator. 14. The solid fuel burner according to claim 9, wherein: a concentrator configured to smoothly reduce and extend the sectional area of the flow path of said fuel nozzle from the inside is provided upstream of said additional air nozzle; said fuel nozzle incorporates therein a separator for dividing the flow path; and the outlet of said additional air nozzle overlaps with said separator, when viewed in the direction perpendicular to the burner shaft. 15. The solid fuel burner according to claim 9, wherein said flame holder discourages the flow of the solid fuel jetting from said fuel nozzle and the carrier gas thereof, and the flow of the air jetting from said at least one air nozzle. 16. The solid fuel burner according to claim 9, wherein said flame holder is a toothed flame holder that discourages the flow of the solid fuel jetting from said fuel nozzle and the carrier gas thereof, and the flow of the air jetting from said at least one air nozzle. 17. The solid fuel burner according to claim 1, wherein a portion, exposed inside said fuel nozzle, of a partition forming said additional air nozzle has a rectangular parallelepiped form that is narrowed toward both upstream and downstream sides of said fuel nozzle, and at least one outlet of said additional air nozzle is provided on a side portion of said rectangular parallelepiped portion. 18. 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 air nozzle, arranged outside the fuel nozzle, for jetting air; and a flame holder provided at a tip end of a partition separating said fuel nozzle and said at least one air nozzle, said flame holder serving as an impediment to a mixture fluid flowing in said fuel nozzle and air flowing in said at least one air nozzle; wherein at least one additional nozzle for jetting a gas for combustion higher in oxygen concentration than said carrier gas and 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 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 gas for combustion are jetted from said fuel nozzle after mixing of the fluid mixture and the gas for combustion, and the fuel is burnt after jetting of the fuel from said fuel nozzle. 19. 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 air nozzle, arranged outside the fuel nozzle, for jetting air; and a flame holder provided at a tip end of a partition separating said fuel nozzle and said at least one air nozzle, said flame holder serving as an impediment to a mixture fluid flowing in said fluid nozzle and air flowing in said at least one air nozzle; wherein at least one additional nozzle for jetting a gas for combustion higher in oxygen concentration than said carrier gas and 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 gas for combustion are jetted from said fuel nozzle after mixing of the fluid mixture and the gas for combustion, and the fuel is burnt after jetting of the fuel from said fuel nozzle.