Solid-fuel burner, combustion device using solid-fuel burner, and method of operating the combustion device

Abstract

Provided is a solid fuel burner ( 60 ) suitable for controlling a flame to be formed by combustion of fuel ejected from the burner ( 60 ) and a temperature distribution in a furnace, a combustion apparatus using the solid fuel burner ( 60 ), and a method of operating the combustion apparatus. Providing in the fuel nozzle ( 10 ) a plurality of gas ejection nozzles ( 81 ), ( 82 ) and a restriction (obstacle) ( 19 ) downstream thereof, and ejecting a relatively large amount of gas from a portion of the gas ejection nozzles ( 81 ) provides a circumferential distribution in fuel concentration. Further, having the restriction (obstacle) ( 19 ) on a downstream side increases a deviation in fuel concentration. Providing a fuel concentration deviation in the circumferential direction makes it possible to change the forming position of a flame. Therefore, regulating the flow rate of gas flowing through the gas ejection nozzles ( 81 ), ( 82 ) makes it possible to control constant the temperature of combustion gas at a furnace exit, the temperature of a heat transfer tube provided on a furnace wall surface, the temperature of a fluid flowing through the heat transfer tube, or the temperature of a heat transfer tube provided in a furnace or at a downstream-side flue portion thereof and the temperature of a fluid flowing through the heat transfer tube.

1 . A solid fuel burner comprising:
 a fuel nozzle for ejecting a fluid mixture of solid fuel and its carrier gas;   at least one air nozzle, arranged outside the fuel nozzle concentrically, for ejecting combustion air;   a plurality of gas ejection nozzles that eject gas are disposed circumferentially inside the fuel nozzle,   a flow regulator that can change an ejection amount of gas from the gas ejection nozzle individually.   
   
   
       2 . The solid fuel burner according to  claim 1 , wherein two or more gas ejection nozzles are provided vertically inside the fuel nozzle. 
   
   
       3 . The solid fuel burner according to  claim 1 , wherein a restriction that once contracts a passage sectional area of the fuel nozzle and then enlarges the passage sectional area to an original size is provided on a downstream-side of the gas ejection nozzles. 
   
   
       4 . The solid fuel burner according to  claim 3 , wherein the restriction is provided on an outer periphery wall that forms the fuel nozzle, or provided on a central axis portion of the fuel nozzle. 
   
   
       5 . The solid fuel burner according to  claim 1 , wherein a fuel nozzle passage on a downstream-side of the gas ejection nozzle provided in the fuel nozzle is divided in a plurality of parts. 
   
   
       6 . The solid fuel burner according to  claim 1 , wherein at a tip portion of a peripheral outer periphery wall of the fuel nozzle, an obstacle that discharges either one or both of a flow of a fluid mixture flowing through the fuel nozzle and a flow of air flowing through the air nozzle is provided. 
   
   
       7 . The solid fuel burner according to  claim 1 , wherein a pipe expanding portion that deflects an air flow in a direction to separate from the fuel nozzle is provided at a tip portion of an outermost air nozzle of the air nozzles. 
   
   
       8 . The solid fuel burner according to  claim 7 , wherein the outermost air nozzle has two or more divided flow passages, and provides flow regulators that can change an ejection amount of air individually. 
   
   
       9 . A combustion apparatus comprising a controller that, based on a combustion gas temperature at an exit of a furnace with the solid fuel burner according to  claim 1  arranged, a surface temperature of a heat transfer tube provided on a furnace wall surface, a surface temperature of a heat transfer tube provided at a downstream-side flue portion of the furnace and/or a temperature of a fluid flowing through the heat transfer tube, controls a flow rate of gas flowing through a gas ejection nozzle provided in the fuel nozzle of the solid fuel burner, individually in a vertical direction of the burner. 
   
   
       10 . An operation method of the combustion apparatus according to  claim 9  comprising:
 when forming flame of solid fuel upward from the solid fuel burner, set a flow rate of gas amount relatively small for the gas ejection nozzles setting on an upper side of the fuel nozzle, and set the flow rate of gas amount relatively large for the gas ejection nozzles setting on a lower side of the fuel nozzle, and   when forming flame of solid fuel downward from the solid fuel burner set the flow rate of gas amount relatively large for the gas ejection nozzles setting on the upper side of the fuel nozzle, and set the flow rate of gas amount relatively larges for the gas ejection nozzles setting on the lower side of the fuel nozzle.   
   
   
       11 . A combustion apparatus comprising; a controller that, based on a combustion gas temperature at an exit of a furnace with the solid fuel burner according to  claim 1  arranged, a surface temperature of a heat transfer tube provided on a furnace wall surface, a surface temperature of a heat transfer tube provided at a downstream-side flue portion of the furnace and/or a temperature of fluid flowing through the heat transfer tube, controls a flow rate of gas flowing through a plurality of gas ejection nozzles provided in the fuel nozzle of the solid fuel burner and a flow rate of air flowing through the outermost air nozzle of the solid fuel burner, individually in a vertical direction of the burner. 
   
   
       12 . An operation method of the combustion apparatus according to  claim 11 , comprising:
 when forming flame of solid fuel upward from the solid fuel burner, set the flow rate of gas amount relatively small for the gas ejection nozzles setting on an upper side of the fuel nozzle and set the flow rate of gas amount relatively large for the gas ejection nozzles setting on an lower side of the fuel nozzle, and set the flow rate of air amount relatively large for the outer side air nozzles setting on the upper side of the fuel nozzle and set the flow rate of air amount relatively small for the outer side air nozzles setting on the lower side of the fuel nozzle   and when forming flame of solid fuel downward from the solid fuel burner, set the flow rate of gas amount relatively large for the gas ejection nozzles setting on the upper side of the fuel nozzle and set the flow rate of gas amount relatively large for the gas ejection nozzles setting on the lower side of the fuel nozzle, and set the flow rate of air amount relatively small for the outer side air nozzles setting on the upper side of the fuel nozzle and set the flow rate of air amount relatively large for the outer side air nozzles setting on the lower side of the fuel nozzle.