Abstract:
A glycerin burning system having a specialized atomizing burner capable of combusting a continuous feed of crude or pure glycerin. The burner preferably includes an impingement nozzle. The nozzle has an internal distributor which mixes two fluid feed streams (glycerin and air) and expels the fluid through an orifice. The distributor has channels which cause the air to swirl before mixing with the glycerin. An impingement pin is provided outside the orifice. The rapidly ejected glycerin/air mixture strikes a target surface on the impingement pin which transforms the mixture into a fine mist having a reduced velocity. The nozzle is located on the central axis of a turbulator which surrounds the atomized spray with rapidly revolving air. An outlet choke is provided on the combustion chamber to limit the speed of the flow so that steady combustion is maintained.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application is a continuation in part of U.S. application Ser. No. 12/069,076, which was filed on Feb. 7, 2008. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       MICROFICHE APPENDIX 
       [0003]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    This invention relates to the field of waste product combustion. More specifically, the present invention comprises a glycerin burning system having a specialized atomizing nozzle for the combustion of glycerin. 
         [0006]    2. Description of the Related Art 
         [0007]    Glycerin, or glycerol, is a byproduct of biodiesel and soap manufacturing. Although there are various uses for pure glycerin, the increase in demand for biodiesel has resulted in the production and stockpiling of large quantities of crude glycerin. This trend is expected to continue. 
         [0008]    Currently there is a need for effective combustion systems for the disposal and heat recovery of glycerin. The most effective glycerin combustion systems typically require a substantial amount of combustion enhancer (an alternate fuel source) to be added to the glycerin in order to achieve the complete combustion of the glycerin. This adds significant cost to the process. 
         [0009]    Existing burners cannot burn pure glycerin because the combustion air speed produced by conventional burners exceeds the flame propagation speed of the air-glycerin mixture. Even if one is able to instantaneously ignite the air-glycerin mixture the flame will be quickly blown away by the burner (a “flame out”). This phenomenon is a major obstacle to the development of effective glycerin combustion systems. An additional fuel—such as alcohol—has traditionally been mixed with the glycerin to increase the flame propagation speed. However, the cost of the alcohol makes the entire process unprofitable. Accordingly, it would be desirable to provide a glycerin burning system which reduces or eliminates the need for a combustion enhancer. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    The present invention comprises a glycerin burning system having a specialized atomizing burner capable of combusting a continuous feed of crude or pure glycerin. The burner preferably includes an impingement nozzle. The nozzle has an internal distributor which mixes two fluid feed streams (glycerin and air) and expels the fluid through an orifice. The distributor has channels which cause the air to swirl before mixing with the glycerin. An impingement pin is provided outside the orifice. The rapidly ejected glycerin/air mixture strikes a target surface on the impingement pin which transforms the mixture into a fine mist having a reduced velocity. 
         [0011]    The nozzle is located on the central axis of a turbulator. The turbulator feeds an additional volume of rapidly moving air around the nozzle. The turbulator includes a set of angled vanes which impart substantial rotation and turbulence to the air as it passes through the device. This air stream collides with the mist of air/glycerin coming off the target surface of the impingement pin. The result is a widely diffused and highly turbulent mixture of air and glycerin. 
         [0012]    This mixture is propelled into a cylindrical combustion chamber where it ignites and burns in a swirling fashion. The far end of the combustion chamber is closed by a choke wall having a choke outlet. The choke outlet is an opening having an area which is smaller than the cross sectional area of the combustion chamber. The opening “chokes” the flow in order to reduce the combustion speed within the combustion chamber and thereby maintain the combustion speed below the flame propagation speed of the air/glycerin mixture. 
         [0013]    The burning system preferably includes the ability to start on a secondary fuel or secondary fuel/glycerin mixture in order to pre-heat the combustion chamber and other components. The system preferably also includes a water purging system to clean the feed lines and combustion chamber when a burning cycle is completed. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0014]      FIG. 1  is a schematic illustration of a glycerin burning system. 
           [0015]      FIG. 2  is a side view, showing a burner for use with the glycerin burning system. 
           [0016]      FIG. 3  is a side view, illustrating the operation of the burner. 
           [0017]      FIG. 4  is an exploded perspective view, showing an impingement mixing nozzle for use with the burner. 
           [0018]      FIG. 5  is a perspective view, showing a distributor for use with the impingement mixing nozzle. 
           [0019]      FIG. 6  is a section view, illustrating the operation of the impingement nozzle. 
           [0020]      FIG. 7  is an elevation view, showing the exit plane of the turbulator. 
           [0021]      FIG. 8  is a perspective view, showing the orientation of the flow-directing vanes in the turbulator. 
           [0022]      FIG. 9  is an exploded perspective view, showing the fuel feed line, the turbulator, and the nozzle. 
           [0023]      FIG. 10  is a perspective view, showing the combustion chamber housing. 
           [0024]      FIG. 11  is a sectioned elevation view, showing the burner attached to the combustion chamber housing. 
           [0025]      FIG. 12  is a sectioned elevation view, showing the burner in operation. 
       
    
    
     REFERENCE NUMERALS IN THE DRAWINGS 
       [0026]      
         [0000]    
       
         
               
               
               
               
             
           
               
                   
               
             
             
               
                 10 
                 glycerin burning system 
                 12 
                 combustion chamber 
               
               
                 14 
                 wall 
                 16 
                 port 
               
               
                 18 
                 conduit 
                 20 
                 burner 
               
               
                 22 
                 nozzle 
                 24 
                 port 
               
               
                 26 
                 exhaust 
                 28 
                 fuel pump 
               
               
                 30 
                 fuel cutoff solenoid 
                 32 
                 air tube 
               
               
                 34 
                 impingement pin 
                 36 
                 flame retention head 
               
               
                 38 
                 fuel feed 
                 40 
                 check valve 
               
               
                 42 
                 purge fluid solenoid 
                 44 
                 ignition transformer 
               
               
                 46 
                 manifold 
                 48 
                 check valve 
               
               
                 50 
                 starter feed 
                 52 
                 water feed 
               
               
                 54 
                 vents 
                 56 
                 orifice 
               
               
                 58 
                 conduit 
                 60 
                 receiver 
               
               
                 62 
                 distributor 
                 64 
                 fuel feed connector 
               
               
                 66 
                 conduit 
                 68 
                 channels 
               
               
                 70 
                 swirl channels 
                 72 
                 orifice 
               
               
                 74 
                 surface 
                 76 
                 surface 
               
               
                 78 
                 combustion zone 
                 80 
                 target surface 
               
               
                 82 
                 turbulator 
                 84 
                 housing 
               
               
                 86 
                 vane 
                 88 
                 central passage 
               
               
                 90 
                 central axis 
                 92 
                 mounting flange 
               
               
                 94 
                 combustion chamber housing 
                 96 
                 cylindrical wall 
               
               
                 98 
                 choke wall 
                 100 
                 choke outlet 
               
               
                 102 
                 mounting wall 
                 104 
                 spray pattern 
               
               
                 106 
                 exhaust flame 
                 108 
                 flame front 
               
               
                 110 
                 burner inlet 
               
               
                   
               
             
          
         
       
     
       DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    The present invention, glycerin burning system  10  is illustrated in  FIG. 1 . Glycerin burning system  10  may be used to burn a continuous feed of raw or pure glycerin. Glycerin burning system  10  generally includes burner  20  which expels glycerin through nozzle  22  into combustion chamber  12  where the glycerin is combusted in combustion zone  78 . Exhaust gases are vented to the atmosphere through exhaust  26 . Air is fed to burner  20  by a burner air blower and a portion of the air fed to burner  20  is diverted into conduit  18  which wraps around wall  14  of combustion chamber  12 . Conduit  18  may be the interior region of a “jacket” surrounding wall  14  or any other conduit suitable for directing the flow of air around combustion chamber  12  while allowing the air to exchange heat with combustion chamber  12 . Ports  24  and  16  are provided in wall  14  and direct heated air toward combustion zone  78 . The direction of hot air towards combustion zone  78  serves two synergistic functions. First, the hot air helps atomize the glycerin expelled from burner  20 . Second, the air flow reduces the effective air velocity of air exiting burner  20 . These two functions work together to mitigate “flare out.” Flare out occurs when the combustion air velocity exceeds the flame propagation speed in the glycerin-air mixture. 
         [0028]      FIG. 2  illustrates burner  20  in greater detail. Burner  20  includes fuel pump  28  which pressurizes the glycerin feeding into burner  20 . During glycerin combustion operations, glycerin passes through fuel cutoff solenoid  30  (when in the open position) through check valve  40  into manifold  46  where it is fed to fuel feed line  38 . Ignition transformer  44  provides a spark to ignite the fuel after it exits nozzle  22  and strikes impingement pin  34 . Starter feed  50  is provided for supplying a feed of a starter fuel (such as alcohol or an alcohol-glycerin mixture) to burner  20  during start-up. The starter fuel is used to heat the combustion chamber to a designed operating temperature before switching to a pure glycerin feed. The starter fuel is supplied to fuel feed line  38  though check valve  48  and manifold  46 . An exterior pump is used to supply the starter fuel to burner  20 . 
         [0029]    Water is used to purge burner  20 , thus cleaning the internal components thereof, upon the cessation of combustion operations. Water is supplied to burner  20  though water feed  52 . Purge fluid solenoid  42  regulates the flow of water to burner  20 . Like the starter fuel, an exterior pump supplies water to water feed  52 . 
         [0030]    Air is supplied to burner  20  by a burner air blower. As mentioned previously, a portion of this air feed is directed into the conduit wrapping around the combustion chamber. The other portion is fed into air tube  32 . Turning to  FIG. 3 , a portion of the air fed into air tube  32  is diverted through vents  54  in flame retention head  36 . Flame retention head  36  helps provide a broad, stable combustion air flow to promote even flame propagation. As mentioned previously, the glycerin is expelled through nozzle  22  where it strikes the tip of impingement pin  34 , diffuses, and mixes with combustion air. 
         [0031]      FIG. 4  shows a detailed view of nozzle  22 . Nozzle  22  is an internal mix nozzle in which a portion of the combustion air is mixed with the glycerin feed as the glycerin passes through conduit  58  and orifice  56  and strikes impingement pin  34 . Distributor  62  rests inside receiver  60 . Distributor  62 , which imparts rotation to the air feed before the air feed begins mixing with the glycerin feed, is shown in greater detail in  FIG. 5 . Distributor  62  has fuel feed connector  64  which connects distributor  62  to the fuel feed line of the burner. Fuel passing through the feed line passes through conduit  66  within distributor  62  and out orifice  72 . Air passes around distributor  62  through channels  68  into swirl channels  70 . Surfaces  74  and  76  mate with the interior of receiver  60  so that air passing around distributor  62  is forced through channels  68  and swirl channels  70 . Swirl channels  70  impart rotation to the air feed by directing the air in angularly about the central axis of conduit  66 . This rotation aids in the mixing and atomization of the glycerin feed as it exits the nozzle. 
         [0032]      FIG. 6  is a section view of nozzle  22  with distributor  62  omitted for greater clarity. Glycerin exiting orifice  72  of conduit  66  is picked up by the rotational air flow passing around distributor. The glycerin passes through conduit and out orifice  56  where it impinges against target surface  80  of impingement pin  34 . This diffuses the air-glycerin mixture, reflecting a portion of the stream back onto the stream exiting orifice  56 . This creates more collision between glycerin and air particles and greater diffusion around impingement pin  34 . This also reduced the velocity of the stream. The glycerin and air mixture passes around impingement pin  34  as a fine mist or fog. Such a nozzle design both reduces combustion air speed and atomizes the glycerin feed for improved flame propagation. 
         [0033]    With the various components of the glycerin burning system now described, operation of the glycerin burning system will be described in greater detail. During start-up, starter fuel is fed to burner  20  through starter feed  50 . The starter fuel passes through check valve  48  and into manifold  46  before passing through fuel feed  38 . Ignition transformer  44  produces a spark as the starter fuel exits nozzle  22 . Starter fuel is fed to burner  20  for a sufficient period of time to heat the combustion chamber to the desired temperature. 
         [0034]    When the desired temperature is reached, fuel pump  28  feeds fuel to manifold  46  through check valve  40 . In order to do this, fuel cutoff solenoid  30  is moved to the open position. The fuel is fed to nozzle  22  where it is atomized and combusted. Check valve  48  prevents the fuel from being forced into starter feed  50 . 
         [0035]    Upon cessation of combustion operations, fuel cutoff solenoid  30  is moved to the closed position and purge fluid solenoid  42  is opened. Water or other purging fluid is fed to burner  20  via water feed  52 . The water passes through purge fluid solenoid  42  into manifold  46 . The water then passes out of burner  20  through fuel feed  38  and nozzle  22 . This cleans the internal components of burner  20  and nozzle  22  to insure that burner  20  and nozzle  22  will last many burning cycles without “gumming up.” Check valve  40  and check valve  48  prevent the purge fluid from passing back into the fuel and starter fluid feed lines. 
         [0036]    A second embodiment of the glycerin burning system is illustrated in  FIGS. 8-12 . As discussed previously, it is important to reduce the combustion speed of the glycerin and air mixture so that a “flame out” does not occur. One approach to reducing the combustion speed is to enhance the dispersion of the atomized glycerin/air mixture at the point where it is injected into the combustion chamber. The second embodiment used a turbulator in combination with an impingement nozzle to enhance the dispersion. 
         [0037]      FIG. 7  shows an elevation view of turbulator  82 . A hollow cylindrical housing  84  defines the outer perimeter of the device. A plurality of radially spaced vanes  86  extend inward from the housing. Central passage  88  remains open to receive the nozzle assembly—as will be described subsequently. 
         [0038]      FIG. 8  shows the exit plane of the turbulator in a perspective view. The reader will note that each vane  86  is angularly offset with respect to central axis  90  (which runs through the center of the housing). In the embodiment shown, each vane is offset approximately 45 degrees from the central axis. The angled vanes force air flowing through the housing to rotate as it exits the housing. In addition, the reader will observe that each vane extends substantially beyond the end of the housing. This fact means that as the air is rotating faster, it escapes the confinement of the housing. Centrifugal force then forces the air to flow outward. The result is a turbulent, spinning air flow which expands outward as it escapes the turbulator. 
         [0039]      FIG. 9  is an exploded perspective view which illustrates how the nozzle assembly is located within the turbulator. Nozzle  22  lies along central axis  90 . Fuel feed  38  passes through the turbulator and connects to nozzle  22  when it is in position. Central passage  88  is preferably sized to just accommodate the diameter of the nozzle. When the nozzle is in position a gap is formed between the turbulator housing and the nozzle. The canted vanes preferably fill substantially all of this gap. 
         [0040]    Mounting flange  92  is provided to mount the turbulator to a combustion chamber housing. The mounting hardware is not significant to the present invention, so the flange illustrated should properly be viewed as one example among many possibilities. 
         [0041]      FIG. 10  shows combustion chamber housing  94 , which is configured for use with the turbulator and nozzle assembly previously illustrated. Cylindrical wall  96  joins a mounting wall on the far side of the view (not shown) and choke wall  98  on the near side of the view. Choke wall  98  includes choke outlet  100 . 
         [0042]    The combustion chamber housing is generally not made of a unitary material. Rather, it is typically made as a steel weldment with a refractory layer on its inner surfaces. However, the material and method of construction of this component is well known to those skilled in the art and—accordingly—it will not be described in further detail. 
         [0043]      FIG. 11  shows a sectioned elevation view with burner  20  being assembled to the combustion chamber housing. Burner  20  is conventionally attached to mounting wall  102 —though this need not always be the case. Combustion chamber  12  is defined by cylindrical wall  96 , mounting wall  102 , and choke wall  98 . Burner  20  is directed toward choke outlet  100  in choke wall  98 . 
         [0044]    Nozzle  22  rests in the middle of turbulator  82 . Fuel feed  38  passes through the turbulator to the nozzle. Pressurized air must be fed into the turbulator housing using any suitable duct (not shown. As discussed previously, pressurized air must also be fed to the nozzle to feed swirl channels  70  (see  FIGS. 4-6 ). 
         [0045]      FIG. 12  shows the assembly in operation. Pressurized air is fed through turbulator  82 . Pressurized glycerin is fed to the nozzle through fuel feed  38 . The swirling turbulator air and wide dispersion from the impingement nozzle produce a wide spray pattern  104 . This spray pattern contains a turbulent mist of glycerin in air. This mixture is ignited to produce a rolling, turbulent flame front  108 . 
         [0046]    Choke outlet  100  is sized to retain the flame front within the combustion chamber housing—in order to avoid a “flame out.” For given feed pressures of air and glycerin, the choke outlet may be sized to produce a steady combustion state in which flame front  108  is appropriately positioned within combustion chamber  12 . RExhaust flame  106  extends out through choke outlet  100 . The heat of the exhaust may be captured to drive an energy recovery device such as a steam turbine. In a more sophisticated embodiment, the diameter of choke outlet  100  could be varied using devices such as are employed on afterburner-equipped jet aircraft engines. 
         [0047]    The flow of gas and combustion products is decelerated to balance the flame propagation speed of the glycerin/air mixture. As the glycerin/air mixture can be difficult to consistently ignite, it is desirable to provide alternate means for initiating the combustion. As described previously, an alternate fuel (such as alcohol) can be supplied to nozzle  22  to start the device. The alcohol is atomized and ignited. The combustion is then allowed to continue until the combustion chamber is well heated and stable combustion exists. At a suitable point, glycerin is phased in and alcohol is phased out. The combustion then continues using glycerin as the only fuel. 
         [0048]    Another alternative is to start the device on a mixture of glycerin and alternate fuel, then shift the mixture to glycerin. As for the previously described embodiments, a water purging system is preferably provided so that the lines can be cleaned after the combustion cycle is completed. In addition, any of the features of the embodiment of  FIGS. 1-3  can be combined with the embodiment of  FIGS. 7-12 . 
         [0049]    The preceding description contains significant detail regarding the novel aspects of the present invention. It should not be construed, however, as limiting the scope of the invention but rather as providing illustrations of the preferred embodiments of the invention. Thus, the scope of the invention should be fixed by the following claims, rather than by the examples given.