Patent Abstract:
A fuel burning device includes a tubular combustion cylinder open at opposing first and second ends. A fuel inlet pipe has a first end extending through the first end of the combustion cylinder partially into the combustion cylinder and a second end extending outside of the combustion cylinder. The fuel burning device also includes a burner head connected to the first end of the fuel inlet pipe and an orifice connected between the burner head and the first end of the fuel inlet pipe. The burner head is structured and arranged so that combusted fuel discharged at the second end of said combustion cylinder has reduced CO and NOx emissions.

Full Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a device and a method of subjecting fuel/air premix to turbulent and vortex air currents to reduce carbon monoxide (CO) and oxides of nitrogen(NOx) emissions. 
       BRIEF SUMMARY OF THE INVENTION 
       [0002]    An object of the invention is to provide a fuel burner that reduces CO and Nox emissions. 
         [0003]    Another object of the invention is to subject fuel/air premix to a naturally aspirated pattern of turbulent air having a curvilinear retrogradation and areas of helicoidal vortex currents of air to eliminate CO while further reducing NOx emissions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0004]    Other objects, features and advantages of the invention will become more apparent after reading the following detailed description of the preferred embodiment of the invention, given with reference to the accompanying drawings, in which: 
           [0005]      FIG. 1  shows a front view of a combustion cylinder according to a first embodiment; 
           [0006]      FIG. 2  shows a front view of a combustion cylinder according to a second embodiment; 
           [0007]      FIG. 3  shows a front view of a combustion cylinder according to a third embodiment; 
           [0008]      FIG. 4  shows a top view of the combustion cylinder of  FIG. 3 ; 
           [0009]      FIG. 5  shows a front view of a combustion cylinder according to a fourth embodiment; 
           [0010]      FIG. 6  shows a top view of the combustion cylinder of  FIG. 5 ; 
           [0011]      FIG. 7  shows a front view of a combustion cylinder according to a fifth embodiment; 
           [0012]      FIG. 8  shows a top view of the combustion cylinder of  FIG. 7 ; 
           [0013]      FIG. 9  shows a front view of a combustion cylinder according to a sixth embodiment; 
           [0014]      FIG. 10  shows a top view of the combustion cylinder of  FIG. 9 ; 
           [0015]      FIGS. 11 and 12  show the combustion cylinder of  FIG. 9  rotated 90° and 180°, respectively, with respect to a longitudinal axis of the cylinder; 
           [0016]      FIGS. 13 and 14  illustrate a front and top view, respectively, of a seventh embodiment having a multiple burner head; 
           [0017]      FIGS. 15 and 16  illustrate a modification of the multiple burner head embodiment with the addition of external vortex fins; 
           [0018]      FIGS. 17 and 18  illustrate a front and top view, respectively, of an eighth embodiment with the burner head raised so that the nozzle cap slots  10  are outside the cylindrical air guide; and 
           [0019]      FIGS. 19 and 20  illustrate a front and top view, respectively, of a ninth embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    A fuel burner as shown in the first embodiment of  FIG. 1  includes a tubular combustion cylinder  1  open at a first extremity  2  and a second extremity  3 . A fuel inlet pipe  5  projects slightly into the combustion cylinder and connects to a hollow air mixer body  6 . An orifice  7  communicates from the fuel inlet pipe  5  into the air mixer body  6 . 
         [0021]    The air mixer body  6  has a proximal end and a distal end. The air mixer body  6  has three primary air inlet holes  8  at the proximal end. One of ordinary skill in the art would recognize that the number and size of such holes may be varied in relation to the size of the orifice  7 . The distal end of the air mixer body  6 , farthest from the first extremity  2 , terminates in a hemispherical nozzle cap  9 . The cap  9  has seven nozzle cap slots  10 . The number and area of the slots may be varied by one skilled in the art in relation to the size of the orifice  7  and the primary air inlet holes  8 . 
         [0022]    Primary ignition of fuel at the nozzle cap slots  10  creates a circular pattern of flame adjacent to an inner wall  4  of the combustion cylinder  1 . The combusted fuel discharges at the second extremity  3 . Since the air mixer body  6  is positioned at the first extremity  2  of the combustion cylinder  1 , an unregulated, turbulent forced air effect develops. In addition, the exterior of the air mixer body  6  and the inner wall  4  together define a secondary area of unregulated, turbulent air for combustion. This turbulent forced air effect increases the pressure at the primary air inlets  8  and reduced CO and NOx emission result. 
         [0023]    The air mixer body  6 , primary air inlet holes  8  and nozzle cap slots  10  may be referred to in totality as a type of burner head. Commercially engineered burner heads of this type are typically engineered to yield 7,500 British Thermal Units (Btu) at 11 inches water column (w.c.) supply pressure for propane gas in free air burn. The embodiment in  FIG. 1  permits an orifice size producing 25,000 Btu at the same supply pressure of propane. As appreciated by one of ordinary skill in the art, reference to propane as a fuel is illustrative without any intent to limit the types of fuel, which may be combusted in this burner with reduced CO and NOx emissions. 
         [0024]    Reduced CO and NOx emissions are obtained by each of the embodiments of the invention. The second embodiment shown in  FIG. 2  illustrates a moveable assemble bracket  11  that is attached to the exterior of the combustion cylinder  1  and the fuel inlet pipe  5 . The manner of attachment and movement may vary without limiting the scope of the invention. The bracket  11  is adjustable to enable the air mixer body  6  to be positioned closer to the second extremity  3  of the combustion cylinder  1 . When the air mixer body  6  is closer to the second extremity  3 , the pressure at the primary air inlet holes  8  increases, so that the resultant combustion reduces CO and NOx emissions even further than in the embodiment of  FIG. 1 . 
         [0025]    The third embodiment illustrated in  FIG. 3  and  FIG. 4  shows the fuel inlet pipe  5  communicating with the air mixer body  6  through a threaded choke adjuster shaft  12 .  FIG. 4  is a view of the embodiment from the second extremity  3  through the combustion cylinder  1  toward the first extremity  2 . 
         [0026]    As seen in  FIG. 3 , a choke adjuster disk  13  with mating thread is attached to the choke adjuster shaft  12 . The choke adjuster disk  13  creates a venturi effect as it is regulated. Such regulation also varies the degree of turbulence of secondary combustion air. This embodiment can be operated with varying percentages of excess air, typically ranging from 3% to 20% for various applications and at various altitudes of sea level. Regulation of the choke adjuster disk  13  also slows the speed of combustion gas through the combustion cylinder  1 , so that CO and NOx emissions are further reduced as compared to the embodiment of  FIG. 1 . 
         [0027]    The fourth embodiment as illustrated in  FIG. 5  and  FIG. 6  shows a turbulence disk  14  attached to the exterior of the air mixer body  6 .  FIG. 6 , similarly to  FIG. 4  is a view of the embodiment from the second extremity  3  through the combustion cylinder  1  toward the first extremity  2 . In this embodiment, two different zones of air pressure in the regulated turbulent secondary combustion air develop after primary ignition. One zone is above and one below the turbulence disk  14 . 
         [0028]    In the embodiment of  FIGS. 5 and 6 , a pattern of turbulence with a curvilinear retrogradation develops in the secondary combustion air upstream of the ignition area of the nozzle cap slots  10 . Although the pattern of turbulence occurs, flame stability is maintained. In addition, positive pressure at the primary air inlet holes  8  is increased and a negative pressure develops at the nozzle cap slots  10 . These changes in pressure improve flame lift-off above the nozzle cap slots  10 , so that CO is practically eliminated while NOx emission is maintained at a reduced level. 
         [0029]    The fifth embodiment as illustrated in  FIG. 7  and  FIG. 8  shows a hollow cylindrical air guide  15  attached to the fuel inlet pipe  5  terminating closest to the second extremity  3  in an air guide aperture  16 , with  FIG. 8  being a same view as  FIGS. 4 and 6  as noted above. The exterior of the air mixer body  6  and interior of the cylindrical air guide  15  define an area of secondary combustion. The interior of the cylindrical air guide  15  confines the pattern of turbulence in the secondary combustion air at the ignition area of the nozzle cap slots  10 , so that the pressure increases further at the primary air inlet holes  8  resulting in further reduction of Nox emission, while CO is still practically eliminated. 
         [0030]    The sixth embodiment as illustrated in  FIGS. 9 and 10  shows a confined cylindrical air guide aperture  16 , with  FIG. 10  being the same view as  FIG. 8  in the fifth embodiment. Several vortex fins  17  project into the air guide aperture  16  closer to the second extremity  3 . Vortex slots  18  fill the interstices between the vortex fins  17 . The force of the naturally aspirated rising air through the vortex slots creates an area of helicoidal vortex air currents in the secondary combustion air. The low-flow velocities of vortex air currents in this area further entrain the fuel-air premix and improve combustion. As a consequence, CO emissions remain practically eliminated (as in the prior embodiment), yet NOx emissions are further reduced. 
         [0031]      FIGS. 11 and 12  completely illustrate the sixth embodiment of  FIG. 9  with the view of  FIG. 11  rotated 90 degrees on the vertical axis., These views are included to more clearly show that air guide  15  is hollow and includes an opening closer to the first extremity  2 . 
         [0032]    One skilled in the art may of course proportionately scale the various orifices, interstices and structures to increase or decrease the amount of input fuel and resulting output Btu power. 
         [0033]      FIGS. 13 and 14  illustrate a multiple burner head of the seventh embodiment.  FIG. 14  is the same view as  FIG. 10  of the prior embodiment. As seen in  FIG. 13 , a lower fuel feed fixture  11 B and an upper fuel feed fixture  11 C are attach to a fuel feed bracket  11 A. The amount of excess combustion air in this embodiment can also be adjusted. Intake holes in an upper choke disk  13 A are aligned through rotation over the intake holes in a lower choke disk  13 B. As illustrated the intake holes are fully aligned and opened. 
         [0034]      FIG. 15  and  FIG. 16  illustrate the seventh embodiment with the addition of external vortex fins  19 .  FIG. 16  is the same view as  FIG. 14  of the prior embodiment. The external vortex fins  19  protrude into a tertiary combustion air flow between the outside of the cylindrical air guide  15  and the combustion cylinder inner wall  4 . A further complimentary area of helicoidal vortex currents result in the cooler tertiary combustion air. Lower combustion temperature further reduces NOx emission. 
         [0035]      FIG. 17  and  FIG. 18  illustrate an eighth embodiment with the burner head raised in the cylindrical air guide  15  such that the nozzle cap slots  10  are closer to the second extremity  3  and outside the cylindrical air guide  15 , with  FIG. 18  being the same view as  FIG. 16  of the prior embodiment. In this embodiment, the flame thereby spreads wider in closer proximity to the combustion cylinder inner wall  4 . Flame entrainment with the slower and cooler airflow velocities of the helicoidal vortex currents in the tertiary combustion air further minimize NOx emissions. 
         [0036]      FIGS. 19 and 20  illustrate a ninth embodiment of the invention. In this embodiment, similar to the embodiment of  FIGS. 17 and 18 , the nozzle cap extends beyond the cylindrical air guide  15 . However, in the ninth embodiment, the nozzle cap slots of  FIG. 18  are replaced by a plurality of nozzle cap holes  21 . In addition, the nozzle cap  9 ′ is conical instead of hemispherical. The nozzle cap  9 ′ has a nozzle cap lip  20  that protrudes from the air mixer body  6 . The nozzle cap lip  20  produces a pattern of turbulence with a curvilinear retrogradation without the addition of a turbulence disk  14  to the air mixer body  6 . 
         [0037]    In each of the embodiments of the invention, NOx reduction is achieved without use of devices such as laterally injected combustion air forming a secondary torroidal recirculation zone in the combustion cylinder  1  further downstream of the primary combustion area. In addition, CO emissions are practically eliminated. 
         [0038]    While the present invention has been described in connection with various preferred embodiments thereof, it is to be understood that those embodiments are provided merely to illustrate the invention, and should not be used as a pretext to limit the scope of protection conferred by the true scope and spirit of the appended claims.

Technology Classification (CPC): 5