document: FIELD OF THE INVENTION 
         [0001]    The present disclosure relates to combustion apparatus, and more particularly, to a burner which may be part of a system including a plurality of interchangeable or modular heat utilizing appliances. 
         BACKGROUND OF THE INVENTION 
         [0002]    Fuel burners are used to operate heat utilizing appliances, such as cooking grills, cooktops, food smoking apparatus, space heaters, and pyrolyzers. It is a great convenience to use a solid fuel in such a burner, as solid fuels such as firewood, charcoal briquettes, and others are readily available. However, despite availability of solid fuels, it is desirable to optimize efficiency of a burner, and to limit unburned fuel emissions. 
           [0003]    It is also desirable to have modular heat utilizing appliances, so that only one burner need be acquired to operate diverse heat utilizing appliances. 
           [0004]    Accordingly, there exists a need for an efficient, clean burning burner capable of being used with diverse heat utilizing appliances. 
         SUMMARY 
         [0005]    The disclosed concepts address the above stated situation by providing a an efficient, clean burning burner and a system for removably attaching heat utilizing appliances thereto. 
           [0006]    The burner has a combustion chamber enclosed by an outer wall surrounding a fuel holder. Air flows both through the fuel holder to support initial combustion, and also around the fuel holder, to be directed to flame and fumes just above the fuel holder to support secondary combustion. A shroud providing a second wall surrounds the outer wall, thereby establishing a flow path for tertiary combustion air also impinging on the flame and fumes, and also providing an external surface cool enough to avoid burns if casually contacted 
           [0007]    The burner has legs holding the combustion chamber well above ground level, and a pivotally coupled ash pan. A perforate food grate is pivotally coupled to the burner, and is movable to a deployed position above the flame, and to a stowed position to the side of the combustion chamber and associated outer walls. Opposite the perforate food grate, a cover is pivotally coupled to the burner, enabling the combustion chamber to be closed to prevent inadvertent ingress of dropped items, inadvertent exposure of the user to heat and exhaust fumes, and to suppress escape of live embers. 
           [0008]    The burner has manual couplings for removably coupling modular heat utilizing appliances to the burner, the modular heat utilizing appliances including closed and open cookers, a food smoker, a space heater, and a pyrolyzer. 
           [0009]    The nature of the disclosed concepts will become readily apparent upon further review of the following specification and drawings. 
       
      
       
         BRIEF DESCRIPTION OF THE DRAWINGS 
           [0010]    Various objects, features, and attendant advantages of the disclosed concepts will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
             [0011]      FIG. 1  is a schematic side view of a burner and modular heat utilizing appliances therefor, with some components shown in cross section, according to at least one aspect of the disclosure; 
             [0012]      FIG. 2  is a schematic side cross sectional view of the burner of  FIG. 1 , according to at least one aspect of the disclosure; 
             [0013]      FIG. 3  is a schematic detail side view of optional components located at the lower central portion of  FIG. 2 ; 
             [0014]      FIG. 4  is a schematic detail side view of the lowermost portion of  FIGS. 1 and 2 ; 
             [0015]      FIG. 5  is a schematic detail side view of components near the lower portion of  FIG. 2 ; 
             [0016]      FIG. 6  is a schematic detail side view of an assembly incorporating the component shown in  FIG. 2  with one of the modular heat utilizing appliances shown in  FIG. 1 , and represented generically in  FIG. 6 ; and 
             [0017]      FIG. 7  is a schematic side view of components of a pyrolyzer partially shown in  FIG. 1 . 
         
      
      
       DETAILED DESCRIPTION OF THE EMBODIMENTS 
         [0018]    Referring first to  FIG. 1 , according to at least one aspect of the disclosure, there is shown an overview of a system comprising a burner  100  for a heat utilizing appliance and a plurality of interchangeable or modular heat utilizing appliances. Only one of the modular heat utilizing appliances is coupled to burner  100  at any one time. 
           [0019]    Referring also to  FIG. 2 , there is shown in greater detail a burner  100  for a heat utilizing appliance. Burner  100  comprises a housing  102  and a fuel holder  104  within housing  100 . Housing  102  may comprise a lateral wall  106  surrounding and spaced apart from fuel holder  104 , and a top wall  108  including a constricted exhaust outlet  110  of transverse dimensions  112  (see  FIG. 1 ) less than transverse dimensions  114  (see  FIG. 1 ) of lateral wall  106 . Constricted exhaust outlet  110  is located above fuel holder  104 . An air inlet opening  116  admits air to fuel holder  104 . Lateral wall  106  and top wall  108  are collectively configured to guide inducted air flowing around fuel holder  104  inwardly from a periphery of housing  102  to join exhaust products flowing upwardly through exhaust outlet  110  when solid fuel  118  is being burned in fuel holder  104 , thereby supporting secondary combustion above fuel holder  104 . 
           [0020]    It should be noted at this point that orientational terms such as over and below refer to the subject drawing as viewed by an observer. The drawing figures depict their subject matter in orientations of normal use, which could obviously change with changes in body posture and position. Therefore, orientational terms must be understood to provide semantic basis for purposes of description only, and do not imply that their subject matter can be used only in one position. 
           [0021]    Exhaust outlet  110  is constricted in that transverse dimension  111  of exhaust outlet  110  is less than a corresponding transverse dimension  113  of housing  102 . This relationship causes top wall  108  and the immediately overlying portion of outer shroud  128  to channel products of combustion and secondary and tertiary combustion air towards exhaust outlet  110 , so that heat may be concentrated advantageously. 
           [0022]    In  FIG. 2 , hinges  158  of cover  154  and  164  of grill  160  are fixed to an outer shroud  128 . Accordingly, respective arms  156  and  162  are L-shaped. 
           [0023]    In  FIGS. 1 and 2 , arrows having outlined heads indicate flow of secondary and tertiary combustion air as combustion air flows by convection through burner  100 . Arrows having solid, filled heads indicates flow of flames and heat produced by combustion of solid fuel  118 . Constricted exhaust outlet  110  may be frustoconical, with the narrowest portion thereof at the center of top wall  108 , as shown, to advantageously concentrate flames and heat at the center of burner  100 . 
           [0024]    Fuel holder  104  may comprise a perforate receptacle  120  enabling air inducted from air inlet opening  116  to come into combustion support relation to solid fuel  118  in fuel holder  104 . Fuel holder  104  may comprise an imperforate lateral wall  124  above perforate receptacle  120 . In some implementations (not shown) of burner  100 , imperforate lateral wall  124  may be eliminated. Perforate receptacle  120  may be made from metallic wire welded into a mesh, for example. Other components of burner  100  exposed to heat of combustion may be fabricated from a suitable metallic alloy, such as a suitable steel. 
           [0025]    Outer shroud  128  may surround and be spaced apart from upper portion  122  of housing  102  of burner  100 . Outer shroud  128  may be configured to constrain air immediately outside housing  102  to flow by convection radially inwardly to join exhaust products flowing upwardly from exhaust outlet  110 , thereby further supporting secondary combustion and also interposing a thermally insulating barrier between lateral wall  106  of housing  102  and an exterior of burner  100 . Similarly, air flowing upwardly past fuel holder  104 , between fuel holder  104  and lateral wall  106 , cools lateral wall  106  and conserves heat taken therefrom, returning recovered heat to flame and exhaust above exhaust outlet  110 . Introduction of secondary and tertiary combustion air will in most cases cause secondary combustion of unburned and partially burned solid fuel  118  to burn so completely that visible smoke is largely eliminated. This decreases both fuel consumption and also air pollution. 
           [0026]    An ash pan  130  may be releasably coupled to burner  100  below fuel holder  104 . Ash pan  130  may comprise a floor  132  and a vertical peripheral wall  134  projecting upwardly from floor  132 . Ash pan  130  thereby forms a sump capable of storing a supply of water  136  to extinguish burning embers (not shown) falling from fuel holder  104 . 
           [0027]    Referring specifically to  FIG. 3 , air inlet opening  116  may open through vertical peripheral wall  134  of ash pan  130 . To this end, air inlet opening  116  may include a conduit  138  and a damper  140  rotatably supported in conduit  138 . A lever  142  controlling rotational position of damper  140  may be provided for manual throttling of combustion air. 
           [0028]    Referring specifically to  FIG. 4 , in some implementations of burner  100 , air inlet opening  116  may open through lateral wall  106  of housing  102 . 
           [0029]    Referring specifically to  FIG. 2 , in some implementations of burner  100 , ash pan  130  is permanently coupled to housing  102  and is movable between a closed position closing a bottom of housing  102  of burner  100  and an open position enabling removal of ashes from ash pan  130 . The closed position is shown in solid lines in  FIG. 2 . The open position is shown in broken lines in  FIG. 2 . Ash pan  130  may be pivotally coupled to housing  102  by a hinge  144 . Pivotal coupling of ash pan  130  retains the former to housing  102 , and also facilitates draining water  136  from ash pan  130 . 
           [0030]    As seen in  FIG. 5 , a hook  146  engageable with a multiple position catch  148  may be employed to secure ash pan  130  in any one of several degrees of inclination from the closed position shown in  FIG. 2 . Hook  146  may be pivotally mounted to ash pan  130  by a hinge  150 . The degrees of inclination may be utilized to control the amount of combustion air entering the interior of housing  102 . 
           [0031]    In summary, burner  100  may comprise an air damper controlling volume of air flow through air inlet opening  116 , the air damper being air damper  140 , or alternatively, ash pan  130  serving as an air damper by virtue of its degree of inclination enabled by multiple position catch  148 . 
           [0032]    Referring to  FIGS. 1, 2, and 4 , burner  100  may comprise at least one leg  152  coupled to and projecting below burner  100 , whereby burner  100  may be supported above a ground surface (not shown). Where one leg  152  is provided, leg  152  may be driven into the ground sufficiently deep as to prevent burner  100  from falling over. Alternatively, where one leg  152  is provided, leg  152  may include an extension (not shown) projecting beneath the center of gravity of burner  100 . Where the latter alternative is provided, the extension will be sufficiently broad as to stably support burner  100  on the ground. As shown in  FIGS. 1, 2, and 4 , a plurality of legs  152 , preferably three legs  152  distributed evenly around housing  102 , may be provided. Leg(s)  152  provide sufficient clearance to enable ash pan  130  to be lowered into the open position shown in broken lines in  FIG. 2  without lifting burner  100  from the ground. 
           [0033]    As shown in  FIG. 2 , burner  100  may further comprise a cover  154  dimensioned and configured to close exhaust outlet  110  of burner  100 . Burner  100  may comprise a hinge  158  pivotally coupling cover  154  to burner  100  by an arm  156 . Cover  154  is solid or imperforate, and prevents inadvertent ingress of objects and a user&#39;s hand and fingers (none of these is shown) into combustion chamber  126 . Cover  154  also prevents emission of live embers from combustion chamber  126 . Cover  154  is shown in a stowed position in solid lines, and approaching a deployed position covering and substantially sealing exhaust outlet  110  in broken lines. 
           [0034]    Burner  100  may further comprise a grill  160  attachable to housing  102  above exhaust outlet  110 . Grill  160  includes openings (not shown) to enable hot gases to pass from combustion chamber  126  through grill  160 . Burner  100  may further comprise a hinge  164  pivotally coupling grill  160  to housing  102  via an arm  162  supported on a post  166 . Hinge  158  of cover  154  may be similarly supported to housing  102  by a post  168 . Grill  160  is shown in a deployed position in solid lines and in a stowed position by broken lines in  FIG. 2 . Cover  154  and grill  160  may be located in diametric opposition on housing  102 , or otherwise located to enable each to be lowered over exhaust outlet  110  without interfering with the other. 
           [0035]    Turning now to  FIG. 6 , burner  100  may further comprise a coupling for detachably coupling a modular heat utilizing appliance  170  to burner  100 . The coupling may comprise at least one draw latch  172 . Two draw latches  172  located in diametric opposition on outer shroud  128  are depicted. However, one or more than two draw latches  172  could be utilized. Draw latches engage projections  176  in well known fashion. Modular heat utilizing appliance  170  generically represents any one of a number of different types of appliances, any one of which may be coupled to burner  100  at one time. 
           [0036]    Again referring to  FIG. 1 , burner  100  may further comprise a modular heat utilizing appliance  170  ( FIG. 6 ) further comprising a cooker  174 A further comprising a cooker housing  178  including a bottom section  180  open to exhaust outlet  110  ( FIG. 2 ) of burner  100 , a top section  182  including a vent  184  for venting exhaust, and a support surface  186  inside cooker  174 , for supporting items being cooked (not shown). Support surface  186  may comprise a wire rack for example. Cooker  174 A is a closed cooker wherein food or other items being cooked are substantially enclosed, for example, to achieve higher cooking temperatures. Top section  182  rests on bottom section  180 , and is readily lifted therefrom. 
           [0037]    Cooker  174 B presents an open, flat cooking surface  188 . Cooker  174 B may include internal baffles  190  to establish a serpentine flow path for exhaust gases from burner  100 . 
           [0038]    Cooker  174 C, intended for smoking, may include a smoking chamber  192  enclosing a wire rack  194 . Smoking chamber  192  is substantially sealed against loss of smoke, apart from vent pipe  194 . 
           [0039]    Burner  100  may further comprise a gas-to-gas heat exchanger  198 , whereby environmental air can be heated for space heating. Gas-to-gas heat exchanger  198  may include internal baffles  200  and a vent  202 . Gas-to-gas heat exchanger may transfer heat by convection, radiation, or both. A powered fan (not shown) may be provided to enhance heat transfer to air. 
           [0040]    Referring also to  FIG. 7 , burner  100  may further comprise a modular heat utilizing appliance further comprising a pyrolyzer  204  including a substantially air-tight heating chamber  206  for pyrolyzing carboniferous materials, such as vegetation (not shown). Heating chamber  206  may include a tightly fitting cap  208  and latches  210  to securely retain cap  208  in place. Heating chamber  206  may be contained within a casing  210  surrounding heating chamber  206  and exposing heating chamber  206  to heat from burner  100 . After transferring heat to heating chamber  206 , products of combustion may be exhausted from vent  212 . 
           [0041]    Referring also to  FIG. 7 , pyrolyzer  204  may further comprise a condenser  214  for condensing vaporized liquid products of pyrolysis conducted to condenser  214  through a conduit  216  in communication with heating chamber  206 . Condenser  214  is a heat exchanger causing vaporized liquid products of pyrolysis to be recovered as liquids. Liquids of different boiling points may be recovered separately, as represented by two capture conduits  218 ,  220 . Gaseous products of pyrolysis may be conducted to a water chamber  222  through a conduit  224 , and bubbled through water  226 . Because heating chamber  206  is sealed, products of pyrolysis will be under sufficient pressure to overcome resistance of water  226 . Gaseous products of pyrolysis may be conducted to a heat exchanger  228  through a conduit  230 , and cooled to a predetermined temperature at which they are deemed safe. Cooled gaseous products of combustion may be collected in a bifurcated conduit  232  for subsequent distribution (conduit  232 B) or use as a fuel in burner  100  (conduit  232 A). Conduits  232 A,  232 B will be understood to include valves (not shown) and other components to achieve functions described herein. 
           [0042]    To these ends, pyrolyzer  204  may further comprise conduit  216 ,  224 ,  230 ,  232 ,  232 A in fluid communication with substantially air-tight heating chamber  206  and with burner  100 , whereby vaporized products of pyrolysis may be conducted to burner  100  for supplementing solid fuel  118  in fuel holder  104 , or for entirely eliminating use of solid fuel  118 . Also, pyrolyzer  204  may further comprise conduits  216 ,  224 ,  230 ,  232 ,  232 B in fluid communication with substantially air-tight heating chamber  206 , an outlet (conduit  232 B) for conducting vaporized products of pyrolysis to an external conduit or storage receptacle (neither shown), and a shutoff valve  234  in the conduit, the shutoff valve enabling control over flow of vaporized products of pyrolysis conducted to the outlet. 
           [0043]    Burner  100  may be provided with a fuel feed feature (not shown) to enable renewing the fuel supply during operation, to enable continuous, long term operation. The fuel feed feature may comprise a door in the outermost wall of burner  100 , and optionally, a chute leading from the door to the opening over exhaust outlet  110 . Solid fuel loaded through the door and forced along the chute will drop into fuel holder  104 . 
           [0044]    While the present invention has been described in connection with what are considered the most practical exemplary embodiments, it is to be understood that the present embodiments are not to be limited to the disclosed arrangements, but rather the description is intended to cover various arrangements which are included within the spirit and scope of the broadest possible interpretation of the appended claims so as to encompass all modifications and equivalent arrangements which are possible. 
           [0045]    It should be understood that the various examples of the apparatus(es) disclosed herein may include any of the components, features, and functionalities of any of the other examples of the apparatus(es) disclosed herein in any feasible combination, and all of such possibilities are intended to be within the spirit and scope of the present disclosure. Many modifications of examples set forth herein will come to mind to one skilled in the art to which the present disclosure pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings.
summary: A burner for burning fuels and modular heat utilizing appliances therefor. The burner includes a fuel holder, an outer wall surrounding the fuel holder and defining a combustion chamber, and optionally, a second wall surrounding the outer wall. Air is inducted from an inlet which may be an ash pan pivotally coupled to the outer wall at the bottom to open the combustion chamber. Supplementary combustion air is conducted to just above the fuel holder by the outer wall. Additional supplementary combustion air is conducted to just above the fuel holder by the second wall. The burner may include a pivotally mounted cooking grate and a pivotally mounted solid cover for closing the combustion chamber, and supporting legs. Modules individually yet replaceably attachable to the burner include a closed or open cooker, a smoker, a space heater, and a pyrolyzer.