Patent Publication Number: US-2023141756-A1

Title: Oven with improved burner assembly

Description:
BACKGROUND OF THE INVENTIONS 
     Field of the Inventions 
     The present inventions relate to ovens, including burner assemblies for large ovens. 
     Description of the Related Art 
     A variety of corn and flour food products, such as tortillas and chips, are made at a commercial scale with large, specialized ovens. A standard oven used in the tortilla production industry consists of multiple decks upon which the tortillas travel as they are being cooked. Each deck typically includes a conveyor belt rotating around several cooking burners. 
     Various problems exist with current ovens. Not only do such ovens consume a great deal of energy, they also require tremendous amount of time and monetary expense to build and adjust for uniform cooking. Thus, parts costs and labor costs for building and operating large ovens are significantly impacted with designs that have higher part counts, higher numbers of assemblies that must be inserted into the internal oven cavity, and more varied arrangements or burners. 
     SUMMARY OF THE INVENTIONS 
     An aspect of at least one of the inventions disclosed herein includes the realization that a burner assembly can be made and installed in a more efficient fashion where the burner assembly includes a central manifold for feeding a fuel mixture to both upstream and downstream arrays of burners. Such a design enables a longer, easier to manufacture and assemble, burner assemblies that can be inserted below the upper surface of a conveyor typically used in large commercial ovens. For example, in such a design, the burner assembly includes an array of upstream burners and an array of downstream burners, all of which are fed air-fuel mixture from a single, centrally disposed manifold. The manifold can include an array of upstream runners and an array of downstream runners feeding the upstream and downstream burners, respectively. This type of arrangement provides a more efficient burner assembly which is easier to assemble within the internal cavity of an oven. 
     Additionally, such an arrangement provides the optional placement of air-fuel flow adjustment valves in close proximity to one another, thereby providing a user with a single location at which they can stand and access the adjustment valves for all of the burners on a single level of a multi-level oven. In some embodiments, the burner assembly can be a multi-level burner assembly, with the intake manifolds stacked vertically. This can provide a simplified plumbing for connecting all of the manifolds to a source of the appropriate air-fuel mixture. Additionally, such an orientation can provide further ease of adjustment of air-fuel mixture flow valves associated with each of the manifolds, efficiently arranged in a vertical spacing. Such an arrangement also provides a user with the option of being located in a single position yet having access to all of the flow control valves for all of the levels of a multi-level oven. 
     Thus, in some embodiments, an oven can include a tortilla oven can comprise an oven enclosure defining an interior, a multi-deck conveyor comprising first, second and third conveyor assemblies, each conveyor assembly comprising an open-type endless conveyor member supported by first and second rotating supports supporting the open-type endless conveyor for rotation causing an upper surface of the open-type endless conveyor member to translate along a conveyance direction, an input end, and an output end. A multi-deck burner assembly comprising first, second and third burner decks, disposed below the upper surfaces of the open-type endless conveyor members of the first second, and third conveyor assemblies, respectively, can comprise an intake manifold comprising an intake port, an interior chamber, an upstream output port and a downstream output port, the intake port configured for connection to a source of a gaseous air-fuel mixture, an upstream plurality of gas output runners connected to the upstream output port of the intake manifold, each of the upstream plurality of gas output runners comprising an inlet end, an output end, an internal passage connecting the inlet end and the outlet end, and an adjustable valve disposed in the internal passage and configured to adjustable restrict flow of the gaseous air-fuel mixture through the internal passage, a downstream plurality of gas output runners connected to the downstream output port of the intake manifold, each of the downstream plurality of gas output runners comprising an inlet end, an output end, an internal passage connecting the inlet end and the outlet end, and an adjustable valve disposed in the internal passage and configured to adjustable restrict flow of the gaseous air-fuel mixture through the internal passage, an upstream plurality of longitudinally extending burners, each comprising an inlet opening connected to the output end of one of the plurality of upstream gas output runners, a closed terminal end, an internal passage portion extending from the inlet opening to the closed terminal end along an upstream direction relative to the conveyance direction, an air/fuel mixture diffuser extending through a wall of the internal passage portion and configured to discharge the gaseous air/fuel mixture from the internal passage portion into the interior of the oven enclosure, and a cradle portion disposed midway between the inlet opening and the closed terminal end, the cradle portion comprising a concave recess defined in an upper portion of the internal passage portion, and a convex by pass portion defining a lower portion of the internal passage extending under the cradle portion, a downstream plurality of longitudinally extending burners, each comprising an inlet opening connected to the output end of one of the plurality of downstream gas output runners, a closed terminal end, an internal passage portion extending from the inlet opening to the closed terminal end along a downstream direction relative to the conveyance direction, an air/fuel mixture diffuser extending through a wall of the internal passage portion and configured to discharge the gaseous air/fuel mixture from the internal passage portion into the interior of the oven enclosure, and a cradle portion, the cradle portion comprising a concave recess defined in an upper portion of the internal passage portion, and a convex by pass portion defining a portion of the internal passage extending under the cradle portion, an upstream pilot flame burner extending latitudinally relative to the upstream plurality of longitudinally extending burners, the upstream pilot flame burner comprising a pilot air/fuel mixture passage having an upper wall, and an upstream pilot air/fuel mixture diffuser extending through the upper wall and configured to discharge the pilot air/fuel mixture from the pilot air/fuel mixture into the interior of the oven, the upstream pilot flame burner extending across and nested in all of the cradle portions of the upstream plurality of longitudinally extending burners, with an upper surface of the upstream pilot flame burner being disposed at approximately a same height as adjacent upper surfaces of the upstream plurality of longitudinally extending burners, a downstream pilot flame burner extending latitudinally relative to the downstream plurality of longitudinally extending burners, the downstream pilot flame burner comprising a pilot air/fuel mixture passage having an upper wall, and a downstream pilot air/fuel mixture diffuser extending through the upper wall and configured to discharge the pilot air/fuel mixture from the pilot air/fuel mixture passage into the interior of the oven, the downstream pilot flame burner extending across and nested in all of the cradle portions of the downstream plurality of longitudinally extending burners, with an upper surface of the downstream pilot flame burner being disposed at approximately a same height as adjacent upper surfaces of the downstream plurality of longitudinally extending burners, at least a first upstream flame sensor positioned adjacent the upstream pilot air/fuel mixture diffuser and configured to detect a presence of flame at the upstream pilot flame burner, and at least a first downstream flame sensor positioned adjacent the downstream pilot air/fuel mixture diffuser and configured to detect a presence of flame at the downstream pilot flame burner. 
     In other embodiments, an oven can comprise an oven enclosure defining an interior, a multi-deck conveyor comprising a plurality of conveyor assemblies, each conveyor assembly comprising an input end, an output end, and an open-type endless conveyor member supported by first and second rotating supports supporting the open-type endless conveyor for rotation causing an upper surface of the open-type endless conveyor member to translate along a conveyance direction. A multi-deck burner assembly comprising a plurality of burner decks, disposed below the upper surfaces of the open-type endless conveyor members of the plurality of conveyor assemblies decks, respectively, can comprise an intake manifold comprising an intake port, an interior chamber, an upstream output port and a downstream output port, the intake port configured for connection to a source of a gaseous air-fuel mixture, an upstream plurality of gas output runners connected to the upstream output port of the intake manifold, each of the upstream plurality of gas output runners comprising an inlet end, an output end, an internal passage connecting the inlet end and the outlet end, a downstream plurality of gas output runners connected to the downstream output port of the intake manifold, each of the downstream plurality of gas output runners comprising an inlet end, an output end, an internal passage connecting the inlet end and the outlet end, an upstream plurality of longitudinally extending burners, each comprising an inlet opening connected to the output end of one of the plurality of upstream gas output runners, a closed terminal end, an internal passage portion extending from the inlet opening to the closed terminal end along an upstream direction relative to the conveyance direction, an air/fuel mixture diffuser extending through a wall of the internal passage portion and configured to discharge the gaseous air/fuel mixture from the internal passage portion into the interior of the oven enclosure, a downstream plurality of longitudinally extending burners, each comprising an inlet opening connected to the output end of one of the plurality of downstream gas output runners, a closed terminal end, an internal passage portion extending from the inlet opening to the closed terminal end along a downstream direction relative to the conveyance direction, an air/fuel mixture diffuser extending through a wall of the internal passage portion and configured to discharge the gaseous air/fuel mixture from the internal passage portion into the interior of the oven enclosure, an upstream pilot flame burner extending latitudinally relative to the upstream plurality of longitudinally extending burners, the upstream pilot flame burner comprising a pilot air/fuel mixture passage having an upper wall, and an upstream pilot air/fuel mixture diffuser extending through the upper wall and configured to discharge the pilot air/fuel mixture from the pilot air/fuel mixture into the interior of the oven, and a downstream pilot flame burner extending latitudinally relative to the downstream plurality of longitudinally extending burners, the downstream pilot flame burner comprising a pilot air/fuel mixture passage having an upper wall, and a downstream pilot air/fuel mixture diffuser extending through the upper wall and configured to discharge the pilot air/fuel mixture from the pilot air/fuel mixture passage into the interior of the oven. 
     In yet other embodiments, a burner assembly for an oven can comprise an intake manifold comprising an intake port, an interior chamber, and an output portion, wherein the intake port configured for connection to a source of a gaseous air-fuel mixture, an upstream plurality of longitudinally extending burners, each comprising an inlet opening fluidically connected to the output portion of the intake manifold and extending away from the manifold along an upstream direction, and a downstream plurality of longitudinally extending burners, each comprising an inlet opening fluidically connected to the output portion of the intake manifold and extending away from the manifold along a downstream direction, generally opposite to the upstream direction. 
     Another aspect of at least one of the inventions disclosed herein includes the realization that arranging a pilot burner approximately halfway down the length of an array of longitudinally arranged burners allows for a generally longer burner assembly. This is because certain regulations regarding pilot burners include limits on the maximum distance any portion of a burner can be away from a pilot burner. For example, in some jurisdictions, the maximum distance a portion of a burner tube can be from a pilot burner is 60 inches. 
     Thus, in some embodiments, a burner assembly includes an array of longitudinally extending burners and a pilot burner extending, for example, latitudinally across the array of longitudinally extending burners, at a position approximately halfway between the upstream and downstream ends of the burners. Thus, the burner tubes can be 2× long. This provides a further optional advantage in allowing for longer burners that reduces parts counts, assembly labor, and the required plumbing. 
     Thus, in some embodiments an oven can comprise an oven enclosure defining an interior, a multi-deck conveyor comprising a plurality of conveyor assemblies, each conveyor assembly comprising an input end, an output end, and an open-type endless conveyor member supported by first and second rotating supports supporting the open-type endless conveyor for rotation causing an upper surface of the open-type endless conveyor member to translate along a conveyance direction. A multi-deck burner assembly comprising a plurality of burner decks, disposed below the upper surfaces of the open-type endless conveyor members of the plurality of conveyor assemblies decks, respectively, can comprise an intake manifold comprising an intake port, an interior chamber, an upstream output port and a downstream output port, the intake port configured for connection to a source of a gaseous air-fuel mixture, an upstream plurality of longitudinally extending burners, each comprising an inlet opening fluidically connected to the upstream output port of the intake manifold, a closed terminal end, an internal passage portion extending from the inlet opening to the closed terminal end along an upstream direction relative to the conveyance direction, an air/fuel mixture diffuser extending through a wall of the internal passage portion and configured to discharge the gaseous air/fuel mixture from the internal passage portion into the interior of the oven enclosure, a downstream plurality of longitudinally extending burners, each comprising an inlet opening fluidically connected to the downstream output port of the intake manifold, a closed terminal end, an internal passage portion extending from the inlet opening to the closed terminal end along a downstream direction relative to the conveyance direction, an air/fuel mixture diffuser extending through a wall of the internal passage portion and configured to discharge the gaseous air/fuel mixture from the internal passage portion into the interior of the oven enclosure, an upstream pilot flame burner extending latitudinally relative to the upstream plurality of longitudinally extending burners, the upstream pilot flame burner comprising a pilot air/fuel mixture passage having an upper wall, and an upstream pilot air/fuel mixture diffuser extending through the upper wall and configured to discharge the pilot air/fuel mixture from the pilot air/fuel mixture into the interior of the oven, the upstream pilot burner positioned at approximately halfway along the longitudinal length of at least one of the upstream plurality of longitudinally extending burners, and a downstream pilot flame burner extending latitudinally relative to the downstream plurality of longitudinally extending burners, the downstream pilot flame burner comprising a pilot air/fuel mixture passage having an upper wall, and a downstream pilot air/fuel mixture diffuser extending through the upper wall and configured to discharge the pilot air/fuel mixture from the pilot air/fuel mixture passage into the interior of the oven, the downstream pilot burner positioned at approximately halfway along a longitudinal length of at least one of the downstream plurality of longitudinally extending burners. 
     In yet other embodiments, a burner assembly for an oven can comprise an intake manifold comprising an intake port, an interior chamber, and an output portion, wherein the intake port configured for connection to a source of a gaseous air-fuel mixture, at least a first plurality of longitudinally extending burners, each comprising an inlet opening fluidically connected to the output portion of the intake manifold, and at least a first pilot flame burner extending latitudinally relative to the first plurality of longitudinally extending burners, the first pilot flame burner being positioned at approximately a halfway along a length of at least one of the first plurality of first longitudinally extending burners. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of an embodiment of an oven including a burner assembly. 
         FIG.  2    is a schematic and partial cutaway view of the oven of  FIG.  1    illustrating a burner assembly in a side elevational view. 
         FIG.  3    is a perspective view of the burner assembly removed from the oven of  FIGS.  1  and  2   . 
         FIG.  4    is a perspective view of a single deck of the burner assembly of  FIG.  3   . 
         FIG.  5 A  is an enlarged perspective view of an intake manifold of the burner deck of  FIG.  4   , with six runners being removed. 
         FIG.  5 B  is another enlarged perspective view of an intake manifold of  FIG.  5 A . 
         FIG.  6    is an enlarged perspective view of the manifold of the burner deck of  FIG.  4   . 
         FIG.  7    is a top plan view of half of the burner deck of  FIG.  4   . 
         FIG.  8    is an enlarged perspective view of a pilot burner, the pilot burner illustrated in  FIG.  7   . 
         FIG.  9    is an enlarged and partial sectional view of the pilot burner illustrated in  FIG.  8   . 
         FIG.  10    is an enlarged perspective view of an end of the burner tube of  FIG.  8   . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The inventions disclosed herein have applicability to ovens used in conjunction with continuously moving conveyor systems, such as those used in large, commercial-grade ovens designed for cooking tortillas. Understanding of the inventions disclosed herein is facilitated with the following description of the application of the principles of the present inventions to ovens for baking tortillas, and in particular, ovens that have a multi-deck conveyor system with burner assemblies disposed directly below the conveyor member. However, the inventions disclosed herein can be used in other contexts as well, including smaller ovens and other devices having elongated burners. 
     With reference to  FIG.  1    the oven  10  can include an improved burner assembly  100  described in greater detail below with reference to  FIGS.  2 - 10   . 
     The oven  10  can include an input section  12 , a baking section  14 , and a discharge section  16  which are typically secured to one another by appropriate fasteners. Each of the sections  12 ,  14 , and  16  can include doors  18  for providing users access to the interior of the oven  30 . 
     With reference to  FIG.  2   , the baking section  14  of the oven  30  is shown in more detail. The baking section  14  can include a plurality of structural components which support a plurality of conveyor assemblies and the burner assembly  100 . The burner assembly receives a mixture of a desired fuel, typically natural gas, and a selected oxidizer, which is typically air. The air-fuel mixture is directed into the burner assembly  100  with pipes (not shown). The flow of the air-fuel mixture into the burner assembly  100  is controlled by regulators (not shown) as known in the art. The exhaust resulting from the combustion of the air-fuel mixture is discharged through an outlet  20 . 
     The inlet section  12  and the outlet section  16  of the oven  30  can each comprise a plurality of drive shafts  22  for supporting gears for driving endless conveyor members  24 ,  26 ,  28 . The endless conveyor members  24 ,  26 ,  28  can be any type of conveyor, often referred to as a “conveyor belt.” However, the conveyor members  24 ,  26 ,  28  are typically made from open stainless steel mesh.  7   
     One or more of the drive shafts  22  for each of the conveyor members  24 ,  26 ,  28  are driven by a motor (not shown) for conveying the conveyor members  24 ,  26 ,  28  in different directions. For example, the conveyor member  24  can be driven such that its upper surface  30  is driven towards the right (as viewed in  FIG.  2   ), the conveyor member  26  can be driven such that its upper surface  32  is driven towards the left (as viewed in  FIG.  2   ), and the conveyor member  28  is driven such that its upper surface  34  is driven towards the right (as viewed in  FIG.  2   ). 
     In operation, uncooked food, such as tortillas, are received into the oven  30  at inlet location  40 . The tortillas are transported from the inlet location  40  along a generally horizontal plane, on the upper surface  30  of the conveyor member  24 . As the tortillas move from the left end of the oven  10  towards the right end (as viewed in  FIG.  2   ), the tortillas pass over a portion of the burner assembly  100 , and are thereby heated. When the tortillas reach the right end of the upper conveyor deck, they are directed onto the upper surface  32  of the middle conveyor member  26  by a chute  42 . The tortillas then pass from the right end of the oven toward the left end of the oven  10 , and again pass over another portion of the burner assembly  100 . When the tortillas reach the left end of the middle conveyor deck, they are directed onto the upper surface  34  of the lower most conveyor member  28  by a chute  44 . The lower most conveyor member  28  then transports the tortillas over the lower most portion of the burner assembly  100  and ultimately to an outlet  46  of the discharge section  16 . 
     This type of oven  10  can be considered a multi-deck oven including a multi-deck burner assembly  100 . 
     With reference to  FIG.  3   , the burner assembly  100  is in the form of a multi-deck burner assembly having a first deck  102 , a second deck  104  and a third deck  106 . The decks  102 ,  104 ,  106  include intake manifolds  112 ,  114 ,  116 , respectively. 
     The intake manifolds  112 ,  114 ,  116  include inlets  122 ,  124 ,  126 , respectively. The intake manifolds  112 ,  114 ,  116 , receive an air-fuel mixture through the inlets  122 ,  124 ,  126  and distribute the air-fuel mixture to arrays of upstream and downstream burners. As noted above with reference to  FIG.  2   , the conveyor members  24 ,  26 ,  28  are arranged to transport food articles in alternating directions. Thus, in this context, the burner assembly  100  in  FIG.  3    has an alternating arrangement of upstream and downstream burner arrays. For example, the first burner deck  102  includes an upstream burner array  130  arranged on the left side of the manifold  112  and a downstream array  132  arranged on the right side of the manifold  112 . The second burner deck  104  includes an upstream burner array  134  and a downstream burner array  136 . Finally, the third deck of burner deck  106  includes an upstream burner array  138  and downstream burner array  140 . 
     Each of the burner decks  102 ,  104 ,  106  also includes one or more pilot burners. In the illustrated embodiment, the upper deck  102  includes an upstream pilot burner  150  and a downstream pilot burner  152 . The second deck  104  includes an upstream pilot burner  154  and a downstream pilot burner  156 . The third deck  106  includes an upstream pilot burner  158  and a downstream pilot burner  160 . When installed for use, all of the manifolds  112 ,  114 ,  116  and all of the pilot burners  150 ,  152 ,  154 ,  156 ,  158 ,  160  are attached to air-fuel mixture sources with appropriate plumbing. The air-fuel mixture received by the manifolds  112 ,  114 ,  116 , is distributed to the upstream and downstream arrays of burners. Further, the pilot burners  150 ,  152 ,  154 ,  156 ,  158 ,  160  are operated to ensure that all of the associated burners remain lit during operation. 
     As shown in  FIG.  3   , the inlets  122 ,  124 ,  126  of the intake manifolds  112 ,  114 ,  116 , respectively, are horizontally offset from each other and face in a generally upward direction. This helps facilitate connecting the appropriate plumbing to the manifolds  112 ,  114 ,  116  so as to provide an air-fuel mixture to all of the inlets  122 ,  124 ,  126 . Other than the different lengths of the intake manifolds  112 ,  114 ,  116 , the remaining structural components of the decks  102 ,  104 ,  106  can be identical or similar. Thus, below, the detailed description of the first deck  102  applies equally to the second and third decks  104 ,  106 . 
     With reference to  FIGS.  4 ,  5 A, and  5 B , the intake manifold  112  includes a plurality of outer walls defining an inner chamber or “plenum”  170 . Additionally, the intake manifold  112  includes an first outlet port  172  and a second outlet port  174 . In operation, air-fuel mixture flows into the inlet  122 , into the interior plenum  170 , then out through the first and second outlet ports  172 ,  174 . 
     In the orientation illustrated in  FIGS.  2  and  3   , the outlet port  172  can be considered an upstream outlet port and the outlet port  174  can be considered a downstream outlet port. As such, the upstream outlet port  172  can be considered as feeding air-fuel mixture to the upstream burner array  130  and the downstream outlet port  174  can serve as feeding air-fuel mixture to the downstream burner array  132 . 
     Optionally, the burner deck  102  can include a throttling body  180 . Optionally, the throttling body  180  can be divided into an upstream throttling unit  182  and a downstream throttling unit  184 . 
     With reference to  FIGS.  5 A and  5 B , only the downstream throttling unit  184  is illustrated, however, the upstream throttling unit  182  can have the same or identical construction. 
     The downstream throttling unit  184  can be in the form of a throttle body having a plurality of individual throttle passages  186   a ,  186   b ,  186   c ,  186   d ,  186   e ,  186   f  (passages  186   e  and  186  shown in  FIG.  5 B . Each of the throttle passages  186   a - 186   e  can have inlet ends attached to an inlet flange  188  and outlet ends attached to an outlet flange  190 . In some embodiments, all of the throttle passages  186   a - 186   f  are welded to each other and to the inlet and outlet flanges  188 ,  190 . Additionally, in the illustrated embodiment, the throttle passages  186   a - 186   f  have a square cross section. However, other shapes can also be used. 
     The throttle body  184  also includes a plurality of valves for optional flow control through each of the throttle passages  186   a - 186   f . For example, in the illustrated embodiment, the throttle body  184  includes butterfly valve assemblies  192   a ,  192   b ,  192   c ,  192   d ,  192   e ,  192   f , attached to the throttle passages  186   a - 186   f , respectively. Each of these butterfly valve assemblies  192   a - 192   f  include a valve shaft (not shown), a valve member (not shown) disposed within the associated throttle passage for pivotal movement between opened and closed positions, in a known manner. Adjustment of the butterfly valves between the opened and closed positions can provide a generally proportional control over the flow rate of air-fuel mixture through the throttle passages  186   a - 186   f . In the illustrated embodiment, the butterfly valve assemblies  192   a - 192   f  include a knob providing for convenient manual adjustment of the angular position of the butterfly valve, and thereby controlling the air-fuel mixture flow rate. A set screw secures the adjustment knob in the desired position. 
     The outlet flange  190  of the downstream throttle body  184  can be connected to a plurality of downstream intake runners  194   a ,  194   b ,  194   c ,  194   d ,  194   e , and  194   f . Like the throttle passages  186   a - 186   f , the intake runners can be attached to each other and an inlet flange  196  by welding or other techniques. In the illustrated embodiment, the intake runners  194   a - 194   f  have approximately the same cross-sectional shape, interior dimensions and exterior dimensions, as the throttle passages  186   a - 186   f , respectively. Aligned as illustrated, each of the throttle passages  186   a - 186   f  provide a flow, metered by the associated butterfly valves  192   a - 192   f , into the corresponding intake runners  194   a - 194   f , respectively. 
     With continued reference to  FIG.  4   , the intake runners  194   a - 194   f  each include outlet ends  196   a - 196   f , respectively. The outlet ends  196   a - 196   f  can be attached to a header plate  198 . The header plate  198  can include passages about the same size as the interior dimensions of the intake runner outlets  196   a - 196   f . The outlet ends  196   a - 196   f  can be attached to the apertures of the header plate  198  by any means, including welding, bonding, etc. In this arrangement, the inlet runners  194   a - 194   f  are configured to independently feed the downstream array of burners  132  which includes burner members  200   a - 200   f.    
     With continued reference to  FIG.  6   , the burner members  200   a - 200   f  are fluidly connected to the outlets  196   a - 196   f  of the intake runners  194   a - 194   f  with transition conduits  202   a - 202   f , respectively. The transition conduits  202   a - 202   f  are mounted to the header member  198  with inlet ends communicating through the header member  198  with the outlets  196   a - 196   f , respectively. Outlet ends of the transition passages  202   a - 202   f  are connected to inlet ends of the burner members  202   a - 202   f , respectively. 
     With reference to  FIG.  7   , the transition passages  202   a - 202   f  can be oriented to extend generally longitudinally along the deck  102 . In some embodiments, the burner members  202   a - 202   f  can also extend longitudinally with or without an angular offset relative to a longitudinal axis L of the deck  102 . In some embodiments, the longitudinal axis L can be considered as extending in the direction of movement of the conveyor member associated with the deck  102  (for example conveyor member  24  of  FIG.  2   ). During operation, food products, such as tortillas, would move along or parallel to the longitudinal axis L. 
     In embodiments where the burner members  200   a - 200   f  are angularly offset relative to the longitudinal axis L, a tortilla moving over the deck  102  would pass over the burners in a manner such that flame discharged from the burner members  200   a - 200   f  would move from one lateral side of the tortilla to the other lateral side, thereby providing a more even heating and thus even cooking of food products as they pass over the burner deck  102 . For example, in some embodiments, the burners  200   a - 200   f  can be angularly offset from the longitudinal axis L by an angle between 0 and 90 degrees. With continued reference to  FIG.  7   , the burner  200   b  is illustrated as being angularly offset from the longitudinal axis L by an angle  210 . The angle  210  can be between 0 and 90 degrees. In some embodiments, the angle  210  is between 75 and 15 degrees. Further, in some embodiments, the angle  210  is between 5 and 25 degrees. As used herein, the term “longitudinally extending” refers to a burner that has a longitudinal component that is larger than its lateral component, for example, where the angle is less than 45 degrees. 
     In the illustrated embodiment, the burners  200   a - 200   c  are all angularly offset from the longitudinal axis L by the same angle. In some embodiments, all of the burners  200   a - 200   f  are offset from the longitudinal axis L by the same angle. In other embodiments, the burners on the right side of the longitudinal axis L (burners  200   a - 200   c ) are offset by the angle  210  while the burners on the left side of the longitudinal axis L (burners  200   d - 200   f ) are offset by an equal but opposite angle  212 . Thus, with regard to the longitudinal axis in the direction of travel T of the conveyor member  24  ( FIG.  2   ), the burners  200   a - 200   f  converge toward the longitudinal axis L from their upstream ends toward their downstream ends. The desired layout and convergence or divergence of the burner members  200   a - 200   f  can be chosen to provide the desired result, for example, more even cooking of food products during operation. 
     Additionally, with reference to  FIG.  4   , the burners included in the upstream burner array  130  are arranged in the opposite orientation, i.e., the upstream array of burners are converged at the upstream end (at their terminal ends) and diverge away from each other toward the downstream end (at their inlet ends), relative to the direction of travel T. This mirror imaged orientation of the upstream burner array and downstream burner arrays  130 ,  132  can help in providing more uniform heating and cooking. 
     Additionally, with reference to  FIGS.  5 A and  5 B , the butterfly valve assemblies  192   a - 192   f  of the throttle bodies  182 ,  184  provide individual adjustment of the flow rate of the air-fuel mixture fed to each individual burner  200   a - 200   f.    
     The burner members  200   a - 200   f  can be formed in any type of burner configuration. In the illustrated embodiment, the burner members  200   a - 200   f  are all formed from a circular cross-sectioned pipe having a groove in their upper wall. The groove is filled with a device known as a “ribbon”  201  which can be formed of a plurality of corrugated sheets of metal layered upon one another to form an array of apertures. When an air-fuel mixture is provided into the interior passages of the burner members  200   a - 200   f , the air-fuel mixture leaks upwardly, out through the ribbon, to support a standing flame thereabove. The ribbon can also be referred to as a “diffuser”. This type of burner is well known in the art and is not discussed in further detail. 
     With reference to  FIG.  8   , and as noted above, the downstream array  132  of the deck  102  includes a burner pilot burner assembly  152 . The upstream pilot burner assembly  150  can have a similar or identical construction to that of the pilot burner assembly  150  and  154 - 160 , although only the pilot burner assembly  152  is described in detail below. 
     With reference to  FIG.  8   , the pilot burner assembly  152  can include an inlet flange  230 , a flexible union member  232  and a main pilot burner member  234 . The inlet flange  230  can be figured to be connected with a source of air-fuel mixture (not shown). The main pilot burner member  234  can include an inlet end  236  and a terminal end  238 . The pilot burner member  234  can be in the form of any type of burner. In the illustrated embodiment, the pilot burner member  234  is the same type of burner as the burner members  200   a - 200   c , however, with a smaller diameter. 
     As such, the main pilot burner member  234  is in the shape of a pipe having a round cross section, an upper groove, and a ribbon member  240  extending through the groove in the upper surface of the main pilot burner member  234 , for discharging a controlled flow of air-fuel mixture from an interior of the member  234 , upwardly, to support a stable flame during operation. The pilot burner assembly  152  can also include a combination igniter and flame sensors  242 ,  244  disposed at opposite ends of the main pilot burner member  234 . The combined igniter and flame sensors  242 ,  238  can include hardware for providing a controlled spark for igniting air-fuel mixtures discharged from the ribbon  240 , as well as functionality for detecting the presence of a flame during operation and output to an air-fuel controller system, as is known in the art. 
     With continued reference to  FIG.  8   , each of the burner members  200   a - 200   f  include cradle portions  250  into which the main pilot burner member  234  is nested. This nesting arrangement helps position the pilot burner assembly  152  in a more desirable orientation and relative positioning for reliable pilot ignition support and even heat distribution. For example, the upper surface of the ribbon member  240  is approximately at the same height as the ribbon members  201  of the burner member  200   a.    
     For example, as illustrated in  FIGS.  9  and  10   , the cradle portion  250  of the burner members (burner member  200   a  being illustrated) includes a U-shaped cradle member  252  disposed in a notch formed in the upper surface of the burner member  200   a . The cradle member  252  partially obstructs the internal passage of the burner member  200   a . Additionally, the cradle portion includes an underpass  260 . 
     The underpass  260  section includes a convex exterior structure attached to a lower portion of the burner member  200   a  for providing an substantially unobstructed cross-sectional flow area for air-fuel mixture to flow under the cradle member  252 . For example, the underpass portion  260  can include endplates  262  and a central, partially cylindrical portion  264  attached to an outer surface of the burner member  200   a . The endplates  262  and central member  264  can be attached to the outer surfaces of the burner member  200   a , by welding, or other techniques. 
     A lower portion of the burner member  200   a  can include cutout  266  thereby opening the interior of the underpass portion  260  to the interior of the upstream and downstream portions of the burner member  200   a . Thus, as shown in  FIG.  9   , a flow of air-fuel mixture F can flow under the cradle member  252  and the pilot burner assembly  152  with additional cross-sectional flow area so as to avoid a constriction of the air-fuel flow F that would otherwise be caused by the pilot burner assembly  152 . 
     With continued reference to  FIG.  7   , the ribbon  201  of the burner member  200   c  is arranged such that the pilot burner assembly  152  passes through approximately a center of the overall length of the ribbon burner. For example, the length  270  of the portion of the ribbon burner of the burner member  200   c  upstream from the pilot burner assembly  152  is approximately equal to the length  272  of the downstream portion of the ribbon burner member of the burner member  200   c . As such, the burner assembly  152  is positioned in a place which helps to maximize the overall allowable length of the burner member  200   c.    
     For example, in some jurisdictions, pilot burners must be placed no more than 60 inches from a pilot burner. Thus, with the pilot burner  152  placed approximately in the center of the ribbon burner  201  of the burner member  200   c , the ribbon burner can extend a maximum allowable length in both the upstream and downstream directions. As such, as noted above, this supports the use of the longest possible, compliant, burner members. 
     As shown in  FIG.  7   , optionally, the burner members  200   a ,  200   b ,  200   c  can have different overall lengths and different lengths of ribbon burner members  201 . For example, the burner member  200   a  can be oriented such that its upstream length  274  is approximately equal to its downstream length  276 , where the overall length (length  274  plus length  276 ) is less than the overall length of the ribbon burner  201  of burner member  200   c  (length  270  plus length  272 ). However, because, in the illustrated embodiment, the ribbon burner  201  of the burner member  200   a  is shorter than the ribbon burner  201  of burner member  200   c , it is not necessary for the ribbon burner  201  of the burner member  200   a  to be centered along the pilot burner  152 . Thus, other orientations can also be used. The ribbon burner of the burner member  200   b  can be arranged in the same or similar manner. 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or embodiments described herein are not intended to limit the scope, applicability, or configuration of the claimed subject matter in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the described embodiment or embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope defined by the claims, which includes known equivalents and foreseeable equivalents at the time of filing this patent application.