Oxidant-swirled fossil fuel injector for a shaft furnace

Abstract

An injector for injecting a swirling oxidant around a fossil fuel into a shaft furnace has a converging nozzle to improve combustion of the fossil fuel and reduce carbon soot formation. Fossil fuels, for example pulverized coal, may be introduced into the blast passageway and/or raceway cavity of a shaft furnace such as a blast furnace or cupola, to reduce the amount of coke needed for operation. Oxidant, which may be industrial grade oxygen, is swirled around the fossil fuel through a converging nozzle to improve the combustion of the fossil fuel thereby permitting increased substitution of fossil fuel for coke.

1 . An injector for injecting a fossil fuel and an oxidant into a shaft furnace comprising: 
 a first conduit having a first end portion for receiving the oxidant and a second end portion for passing the oxidant into at least one of a blast passageway and a raceway cavity, the second end portion terminating substantially with a converging inner surface;    a second conduit having a first end portion for receiving the fossil fuel and a second end portion disposed substantially within the second end portion of the first conduit, the second end portion of the second conduit defining a fossil fuel passage for passing the fossil fuel into at least one of the blast passageway and the raceway cavity; and    a means for swirling the oxidant at least partially disposed between the fossil fuel passage and the second end portion of the first conduit, the means for swirling the oxidant defining a plurality of spiral-like passages having a rotation of at least 90 degrees.    
   
   
       2 . The injector of  claim 1  wherein the plurality of spiral-like passages have a rotation of at least 120 degrees.  
   
   
       3 . The injector of  claim 1  wherein the second conduit comprises the means for swirling the oxidant.  
   
   
       4 . The injector of  claim 1  wherein the means for swirling the oxidant has a shape complementary to the second end portion of the first conduit.  
   
   
       5 . The injector of  claim 1  wherein the leading edge of the second conduit is recessed within the second end portion of the first conduit.  
   
   
       6 . The injector of  claim 1  wherein the means for swirling the oxidant is adjacent to the converging inner surface of the first conduit.  
   
   
       7 . The injector of  claim 1  wherein the converging inner surface of the second end portion of the first conduit and at least one of the second conduit and the means for swirling the oxidant define a converging annular passage for receiving oxidant from the plurality of spiral-like passages.  
   
   
       8 . The injector of  claim 7  wherein the length of the converging annular passage extends through only a portion of the converging inner surface.  
   
   
       9 . The injector of  claim 7  wherein the length of the converging annular passage extends through the entire converging inner surface.  
   
   
       10 . The injector of  claim 1  wherein the plurality of spiral-like passages have an inlet end and an outlet end and wherein the spiral diameter of the plurality of spiral-like passages is greater at the inlet end than at the outlet end.  
   
   
       11 . The injector of  claim 10  wherein spiral diameter is complementary to the second end portion of the first conduit.  
   
   
       12 . The injector of  claim 1  wherein the plurality of spiral-like passages have an average swirl angle of 25° to 65°.  
   
   
       13 . The injector of  claim 12  wherein the swirl angle of the spiral-like passages is substantially constant from the inlet end to the outlet end of the spiral-like passages.  
   
   
       14 . An injector for injecting a fossil fuel and an oxidant into a shaft furnace comprising: 
 a first conduit having a first end portion for receiving the oxidant and a second end portion for passing the oxidant into at least one of a blast passageway and a raceway cavity, the second end portion having a converging inner surface through at least a part of the second end portion and terminating in a first outlet;    a second conduit having a first end portion for receiving the fossil fuel and a second end portion disposed substantially within the second end portion of the first conduit, the second end portion of the second conduit defining a fossil fuel passage for passing the fossil fuel into at least one of the blast passageway and the raceway cavity, the second end portion of the second conduit terminating in a second outlet having a hydraulic diameter; and    a means for swirling the oxidant at least partially disposed between the fossil fuel passage and the second end portion of the first conduit, the means for swirling the oxidant defining a plurality of spiral-like passages having a rotation of at least 90 degrees;    wherein the distance between the geometric center of first outlet and the geometric center of the second outlet is less than the hydraulic diameter of the second outlet.    
   
   
       15 . The injector of  claim 14  wherein the plurality of spiral-like passages have a rotation of at least 120 degrees.  
   
   
       16 . The injector of  claim 14  wherein the converging inner surface of the second end portion of the first conduit and at least one of the second conduit and the means for swirling the oxidant define a converging annular passage for receiving oxidant from the plurality of spiral-like passages.  
   
   
       17 . The injector of  claim 16  wherein the length of the converging annular passage extends through only a portion of the converging inner surface.  
   
   
       18 . The injector of  claim 16  wherein the length of the converging annular passage extends through the entire converging inner surface.  
   
   
       19 . The injector of  claim 14  wherein the plurality of spiral-like passages have an average swirl angle of 25° to 65° and wherein the swirl angle of the spiral-like passages is substantially constant from the inlet end to the outlet end of the spiral-like passages.  
   
   
       20 . An injector for injecting pulverized coal and industrial-grade oxygen into a blast furnace comprising: 
 a first conduit having a first end portion for receiving the industrial-grade oxygen and a second end portion for passing the industrial-grade oxygen into at least one of a blast passageway and a raceway cavity, the second end portion terminating substantially with a converging inner surface; and    a second conduit having a first end portion for receiving the pulverized coal and a second end portion disposed substantially within the second end portion of the first conduit, the second end portion of the second conduit defining a pulverized coal passage for passing the pulverized coal into at least one of the blast passageway and the raceway cavity, the second end portion of the second conduit defining spiral-like passages having a rotation of at least 120 degrees on the outer surface of the second end portion of the second conduit.    
   
   
       21 . A shaft furnace comprising: 
 a blast passageway;    a raceway cavity in fluid communication with the blast passageway; and    an injector for injecting a fossil fuel and an oxidant into at least one of the blast passageway and the raceway cavity, the injector comprising:    a first conduit having a first end portion for receiving the oxidant and a second end portion for passing the oxidant into at least one of the blast passageway and the raceway cavity, the second end portion terminating substantially with a converging inner surface;    a second conduit having a first end portion for receiving the fossil fuel and a second end portion disposed substantially within the second end portion of the first conduit, the second end portion of the second conduit defining a fossil fuel passage for passing the fossil fuel into at least one of the blast passageway and the raceway cavity; and    a means for swirling the oxidant at least partially disposed between the fossil fuel passage and the second end portion of the first conduit, the means for swirling the oxidant defining a plurality of spiral-like passages having a rotation of at least 90 degrees.