Pulverized fuel burner

Abstract

The invention provides a pulverized fuel burner including a nozzle body 6 open to a furnace 1 to inject pulverized fuel together with primary combustion air, flow passages for secondary combustion air formed coaxially around the nozzle body and shutters arranged circumferentially along the flow passages and spaced apart from each other at specified intervals. Non-flow portions are formed by the shutters for the flow passages for the secondary combustion air to bring about backflow of hot flue gas. As a result, ignition performance can be improved with pulverized fuel containing less volatile matter and the flame can be continuously kept stably.

1 . A pulverized fuel burner comprising a nozzle body open to a furnace to inject pulverized fuel together with primary combustion air, flow passages for secondary combustion air formed coaxially around said nozzle body and shutters arranged circumferentially along said flow passages and spaced apart from each other at specified intervals, non-flow portions being formed by said shutters for said flow passages to bring about backflow of hot furnace gas. 
     
     
         2 . A pulverized fuel burner as claimed in  claim 1 , wherein occupied areas of said shutters for said flow passages are variable. 
     
     
         3 . A pulverized fuel burner as claimed in  claim 1 , wherein a movable ring is rotatably arranged coaxially of a front end of said nozzle body, said movable ring having movable guide vanes, fixed guide vanes being arranged on the front end of said nozzle body, each of said movable and fixed guide vanes having a shutter perpendicular to an axis of the nozzle, overlapped state of said two shutters being varied by turning said movable ring. 
     
     
         4 . A pulverized fuel burner as claimed in  claim 1 , wherein said nozzle body is accommodated in a wind box, an air guide duct being arranged in said wind box coaxially of a front end of said nozzle body, a movable ring being rotatably arranged at the front end of said nozzle body, said movable ring having movable guide vanes, said air guide duct having fixed guide vanes, each of said movable and fixed guide vanes having a shutter perpendicular to an axis of the nozzle, overlapped state of said two shutters being varied by turning said movable ring.