Abstract:
The present invention is directed to several embodiments or variations of a fire grate system for a low-emission outdoor fire pit or fire ring. Several of these variations use the same fundamental fire grate framework within the system and are adapted burn liquefied petroleum gas (LPG), a common example of which is propane. A first embodiment of the invention may simulate a wood fire without burning wood by securely attaching artificial ceramic (or similarly constructed) fire logs to a LPG gas-burning fire grate framework. A second, alternative embodiment of the present invention is a gas/wood hybrid system and that uses LPG fuel to reduce emissions from a wood fire.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority to, and the benefit of, U.S. Provisional Application Ser. No. 61/916,951 entitled “LOW-EMISSION OUTDOOR PUBLIC BEACH-TYPE FIRE RING AND RETROFIT DEVICE FOR OUTDOOR PUBLIC BEACH-TYPE FIRE RING,” filed on Dec. 17, 2013, the disclosure of which is herein incorporated by reference in its entirety. 
     
    
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
       [0002]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Technical Field of the Invention 
         [0004]    The present disclosure relates generally to fire pits, such as fire pits for recreation at public beaches. More particularly, the present disclosure relates to an apparatus for improving efficiency of an outdoor public beach-type fire ring in relation to reduction in harmful emissions. 
         [0005]    2. Discussion of the Related Art 
         [0006]    A city&#39;s open space areas, such as beaches and parks, may be protected and preserved as natural resources, visual amenities, and/or recreational opportunities. Recreational fire rings and portable fire pits may be permitted uses in a city&#39;s open space areas, under locally administered laws and ordinances. 
         [0007]    Visitors to public beaches and parks may find a change in the fuels that can be used for the fire rings. This comes about because of renewed interest in reducing harmful pollution including PM 2.5 , carbon monoxide (CO), toxic air pollutants (e.g., benzene and formaldehyde), and climate gases (e.g. methane and black carbon) from burning wood and the promulgation of new regulations to protect and improve air quality. In some regions, if a city&#39;s fire rings are 700 feet or less from residential areas, then the fuel source can only be charcoal unless the rings are spaced out at least 100 feet apart from each other. 
         [0008]    The health benefits associated with reducing PM 2.5  emissions, including wood smoke, are widely accepted as significant. According to the U.S. Environmental Protection Agency (EPA), studies show that exposure to PM 2.5  can cause premature death and harmful effects on the cardiovascular system (the heart, blood, and blood vessels). Particle pollution exposure is also linked to a variety of other public health problems, including respiratory diseases. 
         [0009]    There is a need for apparatus for improving efficiency of an outdoor public beach-type fire ring in relation to reduction in harmful emissions. The present invention, as will be described in more detail below, address this particular need in the art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    According to an aspect of the present disclosure, there is provided several embodiments or variations of a fire grate system for a low-emission outdoor fire pit or fire ring. Several of these variations use the same fundamental fire grate framework within the system and are adapted burn liquefied petroleum gas (LPG), a common example of which is propane. A first embodiment of the invention may simulate a wood fire without burning wood by securely attaching artificial ceramic (or similarly constructed) fire logs to a LPG gas-burning fire grate framework. Ceramic fire logs have traditionally been used in residential gas fireplaces and, within the context of the present invention, will require appropriate sizing and the selection of those fire logs that are robustly constructed to provide a simulated wood fire in an outdoor public setting. 
         [0011]    A second, alternative embodiment of the present invention is a gas/wood hybrid system and that uses LPG fuel to reduce emissions from a wood fire. Wood fires are preferred by many users and the gas/wood hybrid variant constituting the second embodiment is for use in areas where wood fuel is allowable. 
         [0012]    A conversion between the first and second embodiments is envisioned in accordance with the present invention, and may be simply accomplished by the adjustment of gas flow and the addition or removal of the ceramic fire logs to/from the fire grate framework. This convertibility will allow responsiveness to possible changes in future regulations and will provide for devices with similar appearances on the beach. Further, both embodiments will allow traditional open fire cooking activities such as hot dogs and marshmallows. In fact, the cooking experience could be enhanced with the placement of holders for cooking forks, sticks or grills on the fire grate framework. 
         [0013]    It is well established that the use of gaseous hydrocarbon fuels such as natural gas or LPG is a well-recognized approach for the oxidation of products of incomplete combustion (PIC) in industrial applications and is often the primary feature of industrial after burner emission control. The complete oxidation of PIC forms carbon dioxide and water. As well as for industrial air pollutant sources, the oxidation of PIC from the combustion of biomass fuels in residential fireplaces and woodstoves has also been accomplished by the supplemental use of natural gas or LPG combustion. Along these lines, certain embodiments of the present invention include structural modalities to facilitate the introduction of air to a secondary combustion zone and the combustion of natural gas or LPG to oxidize PIC and reduce air emissions. The combustion environment of a fire ring is similar to a simple fireplace and particulate reduction may be obtained with the presently-disclosed fire grate system for a low-emission outdoor fire ring. In this regard, the introduction of air to a secondary combustion zone enhances the oxidation of PIC. 
         [0014]    One or more components associated with LPG storage, flow, regulation, and combustion as integrated into the fire grate system of the present invention may be “off-the-shelf” components primarily designed for use with residential factory manufactured gas fireplaces, residential gas fire log sets, residential gas stoves, residential gas barbecues/smokers, residential fireplace gas log lighters, or camp stoves. Further, the fire grate framework of the fire grate system of the present invention may be fabricated from the same materials (e.g., 330 stainless steel) and possess one or more of the structural and/or functional attributes of Applicant&#39;s current hybrid clean burn system for fireplaces, a more detailed description of which is disclosed in Applicant&#39;s U.S. Design Pat. No. D635,657, U.S. Patent Application Publication No. 2011/0005511, U.S. Patent Application Publication No. 2012/0192855, and U.S. Patent Application Publication No. 2012/0204858, the disclosures of which are herein incorporated by reference in their entireties. The preferred use of stainless steel as a construction material for the presently-disclosed fire grate framework makes it resistant to corrosion from sea salt, mineral acids produced from the possible inappropriate burning of plastics or other trash, and abrasion from wind-blown silica sand. 
         [0015]    The goals of air emission control from outdoor fire rings outfitted with the fire grate system of the present invention include the reduction in PM 2.5  and PM 10 , though there are also other air quality benefits from the present design. Volatile organic compounds (VOC) and carbon monoxide emissions will also be reduced significantly by both of the proposed embodiments/variations of the present invention. Many of the compounds making up VOC are photochemically active and as such participate in ozone formation. Many of the compounds making up VOC from biomass combustion are toxic, mutagenic or carcinogenic, such as formaldehyde, acetaldehyde, and benzene. About one half of the VOC from biomass combustion is made up of methane, a potent greenhouse gas. While not a VOC, the toxicity of carbon monoxide is also well known. As with products of incomplete combustion that make up particles, the use of LPG combustion and secondary combustion in parallel with a wood fire oxidizes VOC into carbon dioxide and water. Similarly, carbon dioxide is produced from carbon monoxide. In addition to the destruction of VOC and carbon monoxide emitted from wood in the LPG/wood hybrid variation, the use of LPG alone without wood in that variation simply will produce much less of these emissions than burning wood. 
         [0016]    In addition to the direct oxidation of particles during a wood fire, the use of supplemental LPG combustion as facilitated by the structural features of certain embodiments of the fire grate system of the present invention reduces the duration of the start-up phase of the fire when combustion conditions are inefficient. Research with residential wood stoves has shown that a disproportionate amount of air emission occur during the “kindling” phase of the fire. In addition, the use of LPG to start the fire reduces the need for starter materials which are often not clean burning. These often include plastics, household waste paper, miscellaneous biomass materials, etc. By using LPG, part of the energy, part of the visual flame production and part of the radiant heat normally produced by wood in a traditional wood fire is replaced by LPG which is inherently cleaner burning. Consequently, a recreational experience of wood flames, radiant heat, and wood smoke aroma can be produced and, as a result burning less wood, harmful emissions can be reduced using the fire grate system of the present invention. 
         [0017]    The present invention is best understood by reference to the following detailed description when read in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Objects and features of the presently-disclosed fire grate system and a gas delivery apparatus for a low-emission outdoor fire pit will become apparent to those of ordinary skill in the art when descriptions of various embodiments thereof are read with reference to the accompanying drawings, of which: 
           [0019]      FIG. 1  is a perspective view of a fire grate system for a low-emission outdoor fire pit in accordance with an embodiment of the present disclosure; 
           [0020]      FIG. 2  is a perspective view of a low-emission outdoor fire pit including a stationary-type fire ring with the fire grate system of  FIG. 1  in accordance with an embodiment of the present disclosure; 
           [0021]      FIG. 3  is a perspective view of a low-emission outdoor fire pit including a fire ring with the fire grate system of  FIG. 1  in accordance with an embodiment of the present disclosure; 
           [0022]      FIG. 4  is a perspective view of a collapsible fire grate system for a low-emission outdoor fire pit, in an first configuration, in accordance with an embodiment of the present disclosure; 
           [0023]      FIG. 5  is a perspective view of the collapsible fire grate system of  FIG. 4 , in a second configuration, in accordance with an embodiment of the present disclosure; 
           [0024]      FIG. 6  is a perspective view of the collapsible fire grate system of  FIG. 4 , in a third configuration, in accordance with an embodiment of the present disclosure; and 
           [0025]      FIG. 7  is a perspective view of a gas delivery apparatus for a low-emission outdoor fire pit in accordance with an embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Hereinafter, embodiments of a fire grate system and a gas delivery apparatus for a low-emission outdoor fire ring or fire pit are described with reference to the accompanying drawings. Like reference numerals may refer to similar or identical elements throughout the description of the figures. 
         [0027]    This description may use the phrases “in an embodiment,” “in embodiments,” “in some embodiments,” or “in other embodiments,” which may each refer to one or more of the same or different embodiments in accordance with the present disclosure. 
         [0028]    Referring now to  FIG. 1 , the fire grate system  100  for a low-emission outdoor fire pit is shown. The predominant structural feature of the fire grate system  100  is a fire grate framework  101 , shown with particularity in  FIG. 1 . The fire grate framework  101  may be made from any suitable material of appropriate temperature and chemical resistance characteristic, e.g., iron, steel, aluminum, ceramics, etc. 
         [0029]    The fire grate framework  101  includes a grate structure  70  configured to provide a cradle for supporting wood (e.g., burning logs) or other material, a gas manifold  50  configured to provide dual gas flow paths, and an air outlet manifold  10 . In some embodiments, as shown for example in  FIG. 1 , the air outlet manifold  10  is configured to be removably coupleable to the gas manifold  50 . 
         [0030]    The grate structure  70  generally includes a configuration of frames (e.g., three frames  71 ,  73 ,  75  shown in  FIG. 1 ) and a configuration of cross bars (e.g., four cross bars  72 ,  74 ,  76 ,  78  shown in  FIG. 1 ) arranged to collectively define a support area “A” configured to receive material, such as combustible material (e.g., wood) or non-combustible material (e.g., ceramic fire logs) thereon. The support area “A” may have an outer perimeter that is generally rectangular in shape. It is to be understood that any suitable length “L 1 ” and any suitable width “W 1 ” may be utilized, e.g., depending on the configuration of a fire ring (e.g., fire ring  200  shown in  FIG. 2 ). In other embodiments, the frames and the cross bars may be arranged in a variety of grate structure configurations, e.g., circular shapes, oblong shapes, angular shapes, curve segments, curvilinear shapes, etc. 
         [0031]    When viewed from the perspective shown in  FIG. 1 , the gas manifold  50  includes an upper manifold tube  20 , a lower manifold tube  30 , and a connector tube  40  disposed in fluid communication between the upper manifold tube  20  and the lower manifold tube  30 . The upper and lower manifold tubes are juxtaposed, extending in spaced, generally parallel relation to each other. In some embodiments, the upper manifold tube  20 , the lower manifold tube  30 , and the connector tube  40  may be integrally formed as a single piece of tubing. A longitudinally-extending gas delivery conduit defined by the upper manifold tube  20  and longitudinally extending gas delivery conduit defined by the lower manifold tube  30  are disposed in fluid communication with each other via the connector tube  40 , which itself fluidly communicates with a gas inlet tube  42  protruding from the approximate center thereof. 
         [0032]    The upper manifold tube  20  defines a plurality of gas distribution apertures  21  in fluid communication with the gas delivery conduit therethrough. Similarly, the lower manifold tube  30  defines a plurality of gas distribution apertures  31  in fluid communication with the gas delivery conduit therethrough. Although a single row of gas distribution apertures  21  associated with the upper manifold tube  20  and a single row of gas distribution apertures  31  associated with the lower manifold tube  30  are shown in  FIG. 1 , a variety of row-column aperture patterns (or other aperture patterns) may be utilized. The size and shape of the gas distribution apertures  21  and the gas distribution apertures  31  may be varied from the configuration shown in  FIG. 1 . 
         [0033]    The air outlet manifold  10  includes an air outlet tube  12  configured to be positioned in a laterally offset relationship from the upper manifold tube  20 . The air outlet tube  12  defines a longitudinally extending air delivery conduit therethrough and a plurality of air distribution apertures  11  in communication with the air delivery conduit. One or more air intake tubes (e.g., three air intake tubes  14   a,    14   b,    14   c ) may be disposed in fluid communication with the air delivery conduit. In the embodiment shown in  FIG. 1 , the air intake tubes  14   a,    14   b,    14   c  are disposed in a side-by-side relationship, and extend in spaced, generally parallel relation to each other. In some embodiments, as shown for example in  FIG. 1 , the air intake tubes  14   a,    14   b,    14   c  each include an upper coupling member  16   a,    16   b,    16   c,  respectively, configured to releasably engage the upper manifold tube  20 , and a lower coupling member  18   a,    18   b,    18   c,  respectively, configured to releasably engage the lower manifold tube  30 . The lower ends of the air intake tubes  14   a,    14   b,    14   c  each further define an air inlet opening. A person of ordinary skill in the art will appreciate that the shape and length of the air intake tubes  14   a,    14   b,    14   c  and the location of the air inlet openings (e.g., in relation to the grate structure  70 ) may be varied from the configuration shown in  FIG. 1 . For example, one or more of the air intake tubes  14   a,    14   b,    14   c  may be configured to place the air inlet opening(s) outside of the perimeter of the grate structure  70 . 
         [0034]    When viewed from the perspective shown in  FIG. 1 , the releasable attachment of the air outlet manifold  10  to the gas manifold  50  through the use of the upper coupling members  16   a ,  16   b,    16   c  and the lower coupling members  18   a,    18   b,    18   c  causes the air outlet tube  12  of air outlet manifold  10  to assume an orientation wherein it extends in spaced, generally parallel relation to, but is further elevated above, the upper manifold tube  20  of the gas manifold  50 . At the same time, the air inlet openings of the air intake tubes  14   a,    14   b,    14   c  are disposed below the lower manifold tube  30  of the gas manifold  50 . The significance of these relative orientations as it pertains to the overall functionality of the fire grate system  100  will be discussed in more detail below. 
         [0035]      FIG. 2  shows a fire pit including the fire grate system  100  as associated with a stationary-type fire ring  200 . Fire ring  200  includes an outer wall  202  and an inner wall  204  defining a cavity therein. A gas feed path  210  constituting part of the fire grate system  100  is provided to supply gas to the inlet tube  42  of the fire grate framework  101  of the fire grate system  100 . The gas feed path  210  includes a suitable conduit (e.g., metal piping or tubing, flexible metal tubing, stainless steel hose), and may include fittings. An on/off valve  215  is integrated into the gas feed path  210  to facilitate hook up with a suitable natural gas or LPG source, such as a propane tank. The valve  215  may have built-in safety devices, e.g., to prevent gas leakage and moisture leakage into the gas feed path  210 . The valve  215  includes a lever arm  217  selectively movable between open and closed positions. Assuming the gas feed path  210  is operatively coupled to a propane tank, the actuation of the lever arm  217  to its open position allows for the flow of propane from the tank (which may be outfitted with its own on/off valve) into the gas feed path  210  via the valve  215 . Conversely, the actuation of the lever arm  217  to its closed position effectively blocks the flow of propane from the tank into the gas feed path  210 . 
         [0036]    Having thus described the structural attributes of the fire grate system  100 , and in particular the fire grate framework  101  thereof, the functional attributes of the fire grate system  100  as integrated into the fire ring  200  will now be described with specific reference to  FIG. 2 . In greater detail, with the fire grate framework  101  being suitably positioned within the cavity of the fire ring  200 , ceramic fire logs or, optionally, conventional wood fire logs are positioned upon the support area “A” of the grate structure  70 . If the fire ring  200  is intended to be used solely in applications or environments wherein wood is not burned therein, it is contemplated that the ceramic fire logs may be pertinently attached to the grate structure  70  within the support area “A” thereof, thus eliminating the separate step of attaching the same to the grate structure  70 . 
         [0037]    With the ceramic fire logs or wood fire logs in place within the support area “A” of the grate structure  70 , the gas feed path is operatively coupled to, for example, a propane supply. The actuation of the lever arm  217  of the valve  215  to its open position facilitates the flow of propane to and into the gas manifold  50  via the gas feed path  210 . As indicated above, it is contemplated that a suitable propane source, such as a conventional propane tank, will be fluidly coupled to the on/off valve  215  prior to the actuation of the lever arm  217  thereof from its closed to its open position. The propane gas entering the connector tube  40  of the gas manifold  50  is in turn channeled into each of the upper and lower manifold tubes  20 ,  30  of the gas manifold  50 . The propane gas exiting the gas distribution apertures  21 ,  31  defined by respective ones of the upper and lower manifold tubes  20 ,  30  is ignited in a conventional manner thus resulting in continuous flame emanation from each of the upper and lower manifold tubes  20 ,  30 , such flame emanation continuing until such time as the actuation lever  217  of the aforementioned on/off valve  215  is moved from its open to its closed position. 
         [0038]    As will be recognized, due to principles of heat convection, over time, flame generation from the upper and lower manifold tubes  20 ,  30  of the gas manifold  50  will result in the temperature of the air proximate the air outlet tube  12  of the air outlet manifold  10  being substantially elevated beyond the temperature of the air proximate the air inlet openings defined by the air intake tubes  14   a,    14   b,    14   c  of the air outlet manifold  10  which are well below the level of the air outlet tube  12 . This temperature differential creates a chimney effect wherein air is circulated through the air outlet manifold  10  in the direction depicted by the arrows included in  FIG. 1 , the air entering the air inlet openings of the air intake tubes  14   a,    14   b,    14   c,  and being dispensed or distributed from the distribution apertures  11  disposed within the air outlet tube  12 . Considering the preferred spatial relationships between the air outlet manifold  10  and the gas manifold  50  as described above, the air emanating from the air outlet tube  12  of the air outlet manifold  10  is introduced into a secondary combustion zone slightly elevated above the gas manifold  50  within the fire grate system  100 , and hence a primary combustion zone defined by ignited gas flowing from the apertures  21 ,  31  of the upper and lower manifold tubes  20 ,  30  of the gas manifold  50 . As described above, the introduction of air into this secondary combustion zone by virtue of the functionality of the air outlet manifold  10  works in concert with the propane combustion occurring at the upper and lower manifold tubes  20 ,  30  of the gas manifold  50  to facilitate the oxidation of products of incomplete combustion, thereby effectively reducing PIC air emissions. 
         [0039]    Referring now to  FIG. 3 , there is shown a fire pit  300  which is a structural variant of the fire ring  200  shown in  FIG. 2 , and is also adapted to accommodate the fire grate system  100  of the present invention. The fire pit  300  includes a peripheral wall  310  which circumvents a floor, both the wall  310  and floor having generally circular configurations, and collectively defining a cavity. Disposed within the wall  310  is a multiplicity of openings  311  which each communicate with the cavity. As shown in  FIG. 3 , each of the openings  311  has a generally quadrangular configuration, though other shapes or arrangements of the openings  311  other than those shown in  FIG. 3  are intended to be encompassed within the spirit and scope of the present invention. The wall  310  also includes a plurality of support legs  320  protruding from a common end thereof, the support legs  320  being adapted to maintain the cavity in an elevated orientation above an underlying support surface. The fire grate system  100 , and in particular the fire grate framework  101  is accommodated within the interior cavity partially defined by the wall  310 . The aforementioned gas feed path  10  is integrated into the wall  310  and or floor of the fire pit  300  and used to facilitate the hook up of the fire grate frame work  101  to a propane tank or other suitable combustible gas supply. 
         [0040]    Referring now to  FIGS. 4-6 , there is shown a fire grate system  500  including a fire grate framework  501  which is a collapsible variant of the above-described fire grate framework  101  integrated into the fire grate system  100  Like the above-described fire grate framework  101 , the fire grate framework  501  may be made from any suitable material of appropriate temperature and chemical resistance characteristic. 
         [0041]    The fire grate framework  501  includes a grate structure  570 , the structural attributes minor those of the grate structure  70  described above in relation to the fire grate system  100 . In this regard, the grate structure generally includes a configuration of frames (e.g., three frames  571 ,  573 ,  575 ) which each have a generally sigma-like configuration, defining a central recessed portion when observed from a horizontal perspective. These frames  571 ,  573 ,  575  and a configuration of cross bars within the grate structure  570  are, as in the grate structure  70 , configured to provide a cradle for supporting wood, ceramic fire logs, or other material. In addition to the grate structure  570 , the fire grate framework  501  includes a gas manifold  550  configured to provide dual gas flow paths, and an air outlet manifold  510 . 
         [0042]    When viewed from the perspective shown in  FIGS. 4-6 , the gas manifold  550  includes an upper manifold tube  520 , a lower manifold tube  530 , and an arcuate connector tube  540  which is integrally connected to and fluidly couples the upper and lower manifold tubes  520 ,  530  to each other. The upper and lower manifold tubes  520 ,  530  are juxtaposed, extending in spaced, generally parallel relation to each other. It is contemplated that the upper and lower manifold tubes  520 ,  530  and intervening connector tube  540  will be integrally formed as a single piece of tubing, suitably bent to assume the overall structure profile (i.e., a generally U-shaped configuration) as shown in  FIGS. 4-6 . A longitudinally extending gas delivery conduit defined by the upper manifold tube  520  and a longitudinally extending gas delivery conduit defined by the lower manifold tube  530  are disposed in fluid communication with each other via the connector tube  540 . 
         [0043]    The upper manifold tube  520  defines a plurality of gas distribution apertures  521  in fluid communication with the gas delivery conduit therethrough. Similarly, the lower manifold tube  530  defines a plurality of gas distribution apertures  531  in fluid communication with the gas delivery conduit therethrough. Although a single row of gas distribution apertures  521  associated with the upper manifold tube  520  and a single row of gas distribution apertures  531  associated with the lower manifold tube  530  are shown in  FIGS. 4-6 , a variety of row-column aperture patterns (or other aperture patterns) may be utilized. In addition, the size and shape of the gas distribution apertures  521 ,  531  may be varied from the configuration shown in  FIGS. 4-6 . 
         [0044]    In the fire grate framework  501 , it is contemplated that the gas manifold  550 , and in particular the lower manifold tube  530  thereof, will be rotatably connected to the grate structure  570 . In greater detail, it is contemplated that the lower manifold tube  530  will be rotatably connected to the aforementioned central recessed portion of each of the three frames  571 ,  573 ,  575  included in the grate structure  570 . As is apparent from  FIGS. 5 and 6 , the distal end of the lower manifold tube  530  protrudes from the frame  571 , and may be used as a gas inlet to facilitate the introduction of natural gas or an LPG such as propane into the gas manifold  550 . The advantages attendant to the rotatable connection of the gas manifold  550  to the grate structure  570  will be described in more detail below. 
         [0045]    The air outlet manifold  510  integrated into the fire grate framework  501  of the fire grate system  500  includes an air outlet tube  512  configured to be positioned in a laterally offset relationship from the upper manifold tube  520 . The air outlet tube  512  defines a longitudinally extending air delivery conduit therethrough and a plurality of air distribution apertures  511  in communication with the air delivery conduit. One or more air intake tubes (e.g., two air intake tubes  514   a,    514   b ) may be disposed in fluid communication with the air delivery conduit. In the embodiment shown in  FIGS. 4-6 , the air intake tubes  514   a,    514   b  extend and space, generally parallel relation to each other, and in a common direction from respective ones of the opposed end portions of the air outlet tube  512 . The air intake tube  514   a  is outfitted with an upper coupling member  517   a  and a lower coupling member  519   a  which have identical, generally quadrangular configurations. The upper coupling member  517   a  accommodates the upper manifold tube  520  of the gas manifold  550  which is extended therethrough. Similarly, the lower coupling member  519   a  accommodates the lower manifold tube  530  which is extended therethrough. Similar to the air intake tube  514   a,  the air intake tube  514   b  is outfitted with an upper coupling member  517   b  and a lower coupling member  519   b,  the structural attributes of which mirror those of the upper and lower coupling members  517   a,    519   a.  Like the upper and lower coupling members  517   a,    519   a  of the air intake tube  514   a,  the upper and lower coupling members  517   b,    519   b  of the air intake tube  514   b  accommodate the upper and lower manifold tubes  520 ,  530  respectively, which are also each extended therethrough. The lower ends of the air intake tubes  514   a,    514   b  each further define an air inlet opening. 
         [0046]    In the fire grate framework  501 , the grate structure  570  is outfitted with a pin P which protrudes laterally outward from the frame  571  thereof in the manner shown in  FIG. 4 . The pin P is selectively insertable into and removable from within a complimentary notch N disposed within the lower coupling member  519   b  of the air intake tube  514   b.  The receipt of the pin P into the notch N is effective to maintain the air outlet manifold  510 , and hence the gas manifold  550 , in the generally vertical orientation shown in  FIG. 4 . The selective removal of the pin P from within the notch N as occurs when the air outlet manifold  510  is lifted or elevated relative to the gas manifold  550  in the manner shown in  FIG. 5  allows the air outlet manifold  510  and gas manifold  550  to be concurrently rotated to a collapsed or stowed position shown in  FIG. 6 . As is apparent from  FIG. 5 , the elevation or lifting of the air outlet manifold  510  to facilitate the removal of the pin P from within the notch N results in the downward movement of the upper manifold tube  520  within the upper coupling members  517   a,    517   b  through which it is extended in comparison to the orientation shown in  FIG. 4 . Similarly, the lower manifold tube  530  is caused to move downwardly within the lower coupling members  519   a,    519   b  through which it is extended in comparison to the orientation shown in  FIG. 4 . 
         [0047]    Subsequent to the air outlet manifold  510  being actuated in the manner shown in  FIG. 5 , as indicated above, the same along with the gas manifold  50  is capable of being rotated in a counter-clockwise direction as viewed from the perspective shown in  FIGS. 4-6  to the generally horizontal, collapsed state shown in  FIG. 6 . The aforementioned rotatable coupling of the gas manifold  550  to the grate structure  570  allows it to be pivoted or rotated to the flattened or collapsed orientation, with the air outlet manifold  510  simultaneously being rotated to precisely the same orientation by virtue of its coupling to the gas manifold  550  via the upper and lower coupling members  517   a,    517   b,    519   a,    519   b.  As further seen in  FIGS. 4-6 , the grate structure  570  is also preferably outfitted with at least one receptacle  577  which is operative to support the air intake tube  514   a,  and hence the air outlet manifold  510  when it, along with the gas manifold  550 , is actuated from its deployed or extended state shown in  FIG. 4  to its stowed or collapsed state shown in  FIG. 6 . Those of ordinary skill in the art will recognize that the fire grate framework  501  and ancillary components such as the gas feed path  210  collectively defining the fire grate system  500  may themselves be integrated into structures such as the fire ring  200  and the fire pit  300  described above. 
         [0048]    Referring now to  FIG. 7 , there is shown a fire grate system  700  including a fire grate framework  701  uniquely configured to accommodate wood arranged in a vertically oriented, tee-pee like configuration. The fire grate framework  701  includes a lower frame assembly  710  which is formed to have a generally hexagonal configuration. In greater detail, the lower frame assembly  710  comprises a plurality of tubular segments  712 , several pairs of which are fluidly connected to each other in end-to-end fashion by intervening elbow connectors  714 . Within the lower frame assembly  710 , several pairs of the segments  712  are fluidly connected to each other in end-to-end fashion by intervening T-connectors  716 . When viewed from the perspective shown in  FIG. 7 , three of these T-connectors  716  have a downwardly protruding branch which is operatively coupled to a corresponding support leg  718 . The distal end of each support leg  718 , which may be tubular, has an end cap  720  attached thereto. The support legs  718  (and hence the T-connectors  716  to which they are attached) are provided in a generally triangular arrangement, thus providing stable support to the lower frame assembly  710  while being operative maintain the same in an elevated orientation above an underlying support surface. 
         [0049]    When also viewed from the perspective shown in  FIG. 7 , two of the T-connectors  716  have an upwardly protruding branch which is fluidly coupled to the bottom end of a respective one of a pair of identically configured, tubular riser members  722 . Finally, one T-connector  716  has a lateral, outwardly protruding branch which defines a gas inlet. 
         [0050]    In the fire grate framework  701 , one of the riser members  722  is fluidly coupled to a first upper frame assembly  724 . In greater detail, the first upper frame assembly  724  comprises a plurality of tubular segments  726 , several pairs of which are fluidly connected to each other in end-to-end fashion by intervening elbow connectors  728 . Within the first upper frame assembly  724 , one of the segments  712  is also fluidly connected to a T-connector  730 . When viewed from the perspective shown in  FIG. 7 , a downwardly protruding branch of such T-connector  730  is fluidly coupled to the top end of the corresponding riser member  722 . Additionally, one of the horizontally extending branches of such T-connector  730  is enclosed by an end cap, as is the distal end of that segment  726  disposed furthest from the T-connector  730 . 
         [0051]    In addition, one of the riser members  722  is fluidly coupled to a second upper frame assembly  732 . In greater detail, the second upper frame assembly  732  comprises a plurality of tubular segments  734 , a pair of which is fluidly connected to each other in end-to-end fashion by an intervening elbow connector  736 . Within the second upper frame assembly  732 , a pair of the segments  734  is also fluidly connected to each other by an intervening T-connector  738 . When viewed from the perspective shown in  FIG. 7 , a downwardly protruding branch of such T-connector  738  is fluidly coupled to the top end of the corresponding riser member  722 . The distal ends of the segments  734  of the outermost pair thereof within the second upper frame assembly  732  are each enclosed by an end cap. 
         [0052]    In the fire grate framework  701 , each of the segments  712 ,  726 ,  734  is provided with a single row of gas distribution apertures  740 . Within the lower frame assembly  710 , the apertures  740  fluidly communicate with the gas delivery conduit collectively defined by the segments  712 , elbow connectors  714  and T-connectors  716 . Within the first upper frame assembly  724 , the apertures  740  fluidly communicate with the gas delivery conduit collectively defined by the segments  726 , elbow connectors  728  and T-connector  730 . Within the second upper frame assembly  732 , the apertures  740  fluidly communicate with the gas delivery conduit collectively defined by the segments  734 , elbow connector  736  and T-connector  738 . The size, shape and/or arrangement of the gas distribution apertures  740  may be varied from the configuration shown in  FIG. 7 . The gas delivery conduits of the first and second upper frame assemblies  724 ,  732  are placed into fluid communication with the gas delivery conduit of the lower frame assembly  710  by respective ones of the riser members  722 , each of which is preferably devoid of any gas distribution apertures. The gas delivery conduit of the lower frame assembly  710  is itself capable of being placed into fluid communication with a combustible gas source via the aforementioned gas inlet defined by one of the T-connectors  716  of the lower frame assembly  710 . 
         [0053]    As indicated above, the structural attributes of the fire grate framework  701 , and in particular the lower, first upper and second upper frame assemblies  710 ,  724 .  732  thereof, make it uniquely suited to accommodate the wooden planks bundled in a tee-pee like arrangement. Additionally, those of ordinary skill in the art will recognize that the fire grate framework  701  may be outfitted with ancillary components such as the gas feed path  210  to collectively define the fire grate system  700 . It is also contemplated that the fire grate system may be sized and configured in a manner which it allows it to be accommodated by, for example, the cavity of the above-described fire ring  200 . 
         [0054]    Although embodiments have been described in detail with reference to the accompanying drawings for the purpose of illustration and description, it is to be understood that the disclosed processes and apparatus are not to be construed as limited thereby. It will be apparent to those of ordinary skill in the art that various modifications to the foregoing embodiments may be made without departing from the scope of the disclosure.