Powder fuel burner

Abstract

A powder fuel burner in a combustion chamber of a boiler includes: a cylindrical air-fuel mixture conveying tube, through which an air-fuel mixture is conveyed and which injects, from a distal end, the air-fuel mixture of powder fuel and conveying air into the combustion chamber; a swirl vane mounted at the distal end of the tube; a rod-shaped center flow blocker mounted on a center axis of the tube upstream of the swirl vane in a conveying direction of the air-fuel mixture, the center flow blocker including a cylindrical surface concentric with the tube and extending in a direction of the center axis; and a cylindrical peripheral flow blocker mounted along an inner wall surface of the tube between the center flow blocker and the swirl vane, the peripheral flow blocker including a cylindrical inner peripheral surface concentric with the tube and extending in the direction of the center axis.

1 . A powder fuel burner mounted in a combustion chamber of a boiler, the powder fuel burner comprising:
 a cylindrical air-fuel mixture conveying tube, through which an air-fuel mixture is conveyed and which injects, from a distal end thereof, the air-fuel mixture into the combustion chamber, the air-fuel mixture being a mixture of a powder fuel and conveying air;   a swirl vane mounted at the distal end of the air-fuel mixture conveying tube;   a rod-shaped center flow blocker mounted on a center axis of the air-fuel mixture conveying tube at a position upstream of the swirl vane in a conveying direction of the air-fuel mixture, the center flow blocker including a cylindrical surface that is concentric with the air-fuel mixture conveying tube and that extends in a direction of the center axis; and   a cylindrical peripheral flow blocker mounted along an inner wall surface of the air-fuel mixture conveying tube between the center flow blocker and the swirl vane, the peripheral flow blocker including a cylindrical inner peripheral surface that is concentric with the air-fuel mixture conveying tube and that extends in the direction of the center axis.   
     
     
         2 . The powder fuel burner according to  claim 1 , wherein
 a diameter of the cylindrical surface of the center flow blocker is greater than or equal to a diameter of the cylindrical inner peripheral surface of the peripheral flow blocker.   
     
     
         3 . The powder fuel burner according to  claim 1 , wherein
 the center flow blocker includes curved surfaces at both ends of the cylindrical surface, respectively, the curved surfaces protruding from the respective ends of the cylindrical surface in the direction of the center axis to form conical side surfaces, respectively, such that angles formed by the center axis and the respective curved surfaces are each less than or equal to 20 degrees, and   the peripheral flow blocker includes curved surfaces at both ends of the cylindrical inner peripheral surface, respectively, the curved surfaces protruding from the respective ends of the inner peripheral surface in the direction of the center axis and connecting to the inner wall surface of the air-fuel mixture conveying tube to form truncated conical side surfaces, respectively, such that angles formed by the inner wall surface of the air-fuel mixture conveying tube and the respective curved surfaces are each less than or equal to 20 degrees.   
     
     
         4 . The powder fuel burner according to  claim 1 , wherein
 the center flow blocker is configured such that a position of the center flow blocker in the direction of the center axis is adjustable.   
     
     
         5 . The powder fuel burner according to  claim 1 , wherein
 the swirl vane includes:   a cylindrical structure that is concentric with the air-fuel mixture conveying tube and that is, at the distal end of the air-fuel mixture conveying tube, mounted inside the air-fuel mixture conveying tube, the cylindrical structure having an internal diameter that is greater than or equal to a diameter of the cylindrical inner peripheral surface of the peripheral flow blocker; and   vanes mounted to an outer peripheral surface of the cylindrical structure.   
     
     
         6 . The powder fuel burner according to  claim 1 , wherein
 the powder fuel is a petroleum residue fuel, a biomass fuel, or a mixed fuel of biomass and pulverized coal.