Biomass center air jet burner

Abstract

A combustion apparatus capable of firing biomass fuel including a burner assembly which includes a biomass nozzle concentrically surrounded by a core air zone and extending axially along the length of the core air zone, the burner assembly residing within a windbox, the windbox being attached to a furnace of a boiler, and the burner assembly being connected to the furnace by a burner throat, through which air and fuel supplied to the burner assembly are emitted into the furnace.

1 . A combustion apparatus capable of firing biomass fuel, comprising:
 a burner assembly comprising a biomass nozzle concentrically surrounded by a core air zone and extending axially along a length of said core air zone, said burner assembly residing within a windbox, said windbox being attached to a furnace of a boiler, said burner assembly being connected to said furnace by a burner throat, through which air and fuel supplied to the burner assembly are emitted into the furnace;   a forced draft fan providing a first supply of air to said windbox;   a core air duct, enclosing said core air zone, for receiving a core portion of said first supply of air, said core air duct having a core damper for regulating said core portion entering said core air duct;   a core nozzle for receiving said core portion from said core air duct, said core nozzle delivering said core portion to said burner throat;   a burner elbow for receiving pulverized coal and a second supply of air; said pulverized coal and said second supply of air continuing through a coal nozzle, in an annulus formed between said core nozzle and said coal nozzle, said core portion serving to accelerate ignition of pulverized coal by contacting an inner cylinder of a coal jet leaving said coal nozzle; said core portion also serving to accelerate combustion.   
     
     
         2 . The combustion apparatus according to  claim 1 , wherein said burner assembly is operated in combination with an over-fire-air system. 
     
     
         3 . The combustion apparatus according to  claim 1 , further comprising a reducer for reducing the cross-sectional area of said biomass nozzle. 
     
     
         4 . The combustion apparatus according to  claim 1 , further comprising a reducing taper affixed to an exit of said biomass nozzle to accelerate the biomass fuel as said biomass fuel enters said furnace to prevent flashback into said biomass nozzle. 
     
     
         5 . The combustion apparatus according to  claim 1 , further comprising at least one deflector near an exit of said biomass nozzle for increasing mixing rates of said biomass fuel with said core portion. 
     
     
         6 . The combustion apparatus according to  claim 1 , further comprising at least one swirler near an exit of said biomass nozzle for increasing mixing rates of biomass fuel with said core portion. 
     
     
         7 . The combustion apparatus according to  claim 1 , wherein said first supply of air is heated by an air preheater. 
     
     
         8 . A method of operating the combustion apparatus according to  claim 1 , comprising providing a first valve and a second valve, wherein when biomass is not being supplied, said first valve is closed and said second valve is opened and adjusted in combination with said core damper to supply a desired amount of said core portion, and when biomass is supplied, said second valve is shut and said first valve is opened to admit biomass and transport air. 
     
     
         9 . A biomass center air jet burner comprising a biomass pipe defining a biomass zone therein, an axial pipe concentrically surrounding the biomass pipe and defining an axial zone there between, an annular pipe concentrically surrounding the axial pipe defining a first annular zone there between, a barrel concentrically surrounding the annular pipe defining a second annular zone there between, a burner zone wall concentrically surrounding the barrel defining a third annular zone there between, a core air duct radially interposed between the axial pipe and the annular pipe, wherein the core air duct provides fluid communication between the axial zone and a windbox, and a means for conditioning a pulverized coal flow around a portion of the feeder duct contained in the first annular zone. 
     
     
         10 . A burner as recited in  claim 9  wherein the biomass pipe has a biomass nozzle tip that terminates within the axial pipe and prior to the core air duct. 
     
     
         11 . A burner as recited in  claim 9  wherein the biomass pipe has a biomass nozzle tip that terminates within a burner assembly and downstream of the core air duct. 
     
     
         12 . A burner as recited in  claim 11  wherein the biomass nozzle tip radially expands within the burner assembly. 
     
     
         13 . A burner assembly as recited in  claim 11  wherein the biomass nozzle tip radially reduces within the burner assembly. 
     
     
         14 . A burner assembly as recited in  claim 11  wherein the biomass pipe further comprises of a flow valve. 
     
     
         15 . A burner assembly as recited in  claim 14  wherein the biomass nozzle is longitudinally adjustable along the length of the burner assembly. 
     
     
         16 . A burner assembly as recited in  claim 15 , wherein the first annular zone contains a flow conditioning device. 
     
     
         17 . A burner as recited in  claim 16 , wherein the biomass pipe further comprises a reducer downstream of the flow valve. 
     
     
         18 . A burner as recited in  claim 11 , further comprising a means for providing the first annular zone with a pulverized coal and a separate means from providing the biomass pipe with a biomass fuel. 
     
     
         19 . A burner as recited in  claim 17 , further comprising a means for providing the first annular zone with a pulverized coal and a separate means from providing the biomass pipe with a biomass fuel. 
     
     
         20 . A burner as recited in  claim 19 , further comprising a vane in the second annular zone, a vane in the third annular zone, and wherein the second annular zone and the third annular zone are in fluid communication with the windbox.