Counterflow Fuel Injection Nozzle in a Burner-Boiler System

Abstract

A counterflow fuel injection nozzle for injecting fuel is disclosed. The nozzle includes a nozzle wall having an interior surface that defines a nozzle interior, the interior for receiving a fuel therein. The nozzle further has a fuel passageway formed in the nozzle wall for distributing the fuel from the interior to a location exterior of the nozzle, the fuel distributed to the exterior location in a fuel flow injection direction. An airstream is provided in a prevailing air flow direction in the location exterior of the nozzle. At least one vector component of the fuel flow injection direction opposes at least one vector component of the prevailing air flow direction. In this manner, by distributing fuel into an air flow at a counterflow angle, improved control of mixing of the fuel in the air is achieved. The counterflow nozzle may be included as part of a new burner or as a retrofit to existing burners in order to incorporate counterflow mixing. Advantageously, burner turndown ratios and stability are enhanced through the use of the counterflow fuel injection nozzles with burners that use FGR (i.e., have lower O 2 in combustion air supplied to the burner).

1 . A counterflow fuel injection nozzle for injecting a gaseous fuel, the nozzle comprising: 
 a nozzle wall having an interior surface that defines a nozzle interior, the interior for receiving a fuel therein, the nozzle further having a plurality of fuel passageways formed in the nozzle wall for distributing the fuel from the interior to a location exterior of the nozzle, the fuel distributed to the exterior location in a fuel flow injection direction;    wherein, when an airstream is provided in a prevailing air flow direction in the location exterior of the nozzle, at least one vector component of the fuel flow injection direction opposes at least one vector component of the prevailing air flow direction.    
     
     
         2 . The counterflow fuel injection nozzle of  claim 1  wherein at least one of the fuel passageways terminates in an opening having a diameter in a range of between about 0.063 inches to about 0.189 inches.  
     
     
         3 . The counterflow fuel injection nozzle of  claim 2  wherein the opening has a diameter of about 0.1875 inches.  
     
     
         4 . The counterflow fuel injection nozzle of  claim 3  where in the nozzle is used to generate steam and/or hot water.  
     
     
         5 . The counterflow fuel injection nozzle of  claim 4  wherein the nozzle is used in a combustion apparatus.  
     
     
         6 . A combustion apparatus comprising: 
 a plurality of radially disposed lances, each of the lances connected to at least one of a plurality of counterflow fuel injection nozzles for injecting a gaseous fuel;    wherein each of the fuel injection nozzles includes: a nozzle wall having an interior surface that defines a nozzle interior, the interior for receiving a fuel therein, and each of the nozzles further includes a plurality of fuel passageways formed in the nozzle wall for distributing the fuel from the interior to a location exterior of each nozzle, the fuel distributed to the exterior location in a fuel flow injection direction; and    wherein, when an airstream is provided in a prevailing air flow direction in the location exterior of the each nozzle, at least one vector component of the fuel flow injection direction opposes at least one vector component of the prevailing air flow direction.