External fuel ultra low NOX burner

Abstract

A system and method for reducing NOx in a burner assembly utilizes simultaneous emission high-pressure staged fuel and low-pressure primary / stability fuel on a burner tile to achieve low-pressure stability with high-pressure firing.

Description

EXTERNAL FUEL ULTRA LOW NOX BURNERFIELD OF THE INVENTION

[0001] The present disclosure is directed to a burner that includes an arrangement of fuel nozzles that discharge at different pressures to improve burner performance and emission (e.g. NOx, CO, Noise, etc.) products of combustion. More specifically, the present disclosure includes a burner having a burner tile and fuel nozzles that cooperate with the burner tile to establish a constant ignition source for the burner without the need of any stabilization media or fuel within the burner throat such that all of the combustion takes place outside the burner throat.BACKGROUND

[0002] Ultra Low NOx (ULN) burners are known to utilize flue-gas entrainment, using the energy of incoming fuel and air streams, to minimize the amount of thermal NOx produced as the entrained flue gas reduces the adiabatic flame temperature of the combustion process. Such burners are used in new builds or retrofitted in existing applications. Key performance factors include a need to maintain stable combustion and compact flames while also maintaining and low emissions and reducing reliability concerns. As emission standards continue to be tightened in view of environmental concerns, existing ULN burners are being challenged for improvements that unintendedly result in a sacrifice of one or several of those key performance factors.

[0003] While prior art devices have focused on the structure of the burner tiles and location of combustions zones to achieve ultra-low NOx emissions, resultant burner designs have the tendency to add complexity to the burner structure either increasing flame volumes or decreasing burner reliability given the numerous additions of consumables. There continues to be a need to improve the performance of the burners through looking at the holistic performance of the burner structure in a manner that does not sacrifice those key performance factors. In addition, there is a need to structure such improved burners in a way that allows them to be easily retrofitted in existing designs to allow the improvementof any such development to be realized in existing applications. This need for improvement in combustion stability, flame volumes, emissions output, reliability, and retrofitability is further constrained by the need to provide these capabilities economically.SUMMARY

[0004] The present disclosure includes one or more of the features recited in the appended claims and / or the following features which, alone or in any combination, may comprise patentable subject matter.

[0005] According to a first aspect of the present disclosure, a burner includes a burner tile and a plurality of fuel nozzles positioned adjacent the burner tile. The burner tile has a slanted surface about the periphery of the exterior burner tile. The slanted surface is formed to include a flow disruptor about the periphery of the burner tile and a combustion air passageway through the interior of the burner tile. Each fuel nozzle is configured to be connected to a source of fuel and to emit a low-pressure stream of fuel against the sloped surface and a higher-pressure stream of fuel directed towards the periphery of the burner tile.

[0006] According some embodiments of the first aspect, the slanted surface has an upper portion above the flow disruptor and a lower portion below the flow disruptor.

[0007] According some embodiments of the first aspect, the low-pressure fuel is directed onto the lower portion of the slanted surface.

[0008] According some embodiments of the first aspect, each fuel nozzle includes a first chamber and a second chamber, the second chamber separated from the first chamber by a pressure reducer.

[0009] According some embodiments of the first aspect, the low-pressure stream of fuel is emitted from the second chamber.

[0010] According some embodiments of the first aspect, the high-pressure fuel is emitted from the first chamber.

[0011] According some embodiments of the first aspect, each fuel nozzle of the plurality of fuel nozzles includes at least two orifices emitting independent streams low- pressure fuel and at least two orifices emitting independent high-pressure fuel.

[0012] According some embodiments of the first aspect, each one of the plurality of fuel nozzles emits first and second streams of low-pressure fuel such that a first stream of low-pressure fuel from a first one of the plurality of fuel nozzles is directed to intersect a second stream of low-pressure fuel from a second one of the plurality of fuel nozzles.

[0013] According some embodiments of the first aspect, each one of the plurality of fuel nozzles emits first and second streams of high-pressure fuel such that a first stream of high-pressure fuel from a first one of the plurality of fuel nozzles is directed to intersect a second stream of high-pressure fuel from a second one of the plurality of fuel nozzles.

[0014] According some embodiments of the first aspect, the slanted surface has a first diameter at first end of the burner tile where combustion air exits the burner tile and the diameter of the slanted surface increases as the distance from the first end increases.

[0015] According to a second aspect of the present disclosure, a burner includes a burner tile and a plurality of fuel nozzles. The burner tile is attachable to a portion of a furnace compartment. The burner tile is formed to include a cylindrical inner passageway for conducting combustion air and a frustoconical exterior face having a channel formed in the frustoconical exterior face. The channel separates the frustoconical exterior face into a lower surface and an upper surface. The plurality of fuel nozzles are positioned adjacent the burner tile. The plurality of fuel nozzles each include at least one low-pressure port and at least one high-pressure port. The at least one high-pressure port is positioned to direct high-pressure combustion fuel above the burner tile cylindrical inner passageway. The at least one low-pressure port is positioned to directed low-pressure combustion fuel against the lower surface of the frustoconical face.

[0016] According some embodiments of the second aspect, each fuel nozzle includes at least two high-pressure ports and at least two low-pressure ports.

[0017] According some embodiments of the second aspect, a fuel nozzle includes a first chamber configured to receive high-pressure fuel from a manifold and to conduct the high-pressure fuel to the at least one high-pressure port. In some embodiments, the fuel nozzle further includes a second chamber in fluid communication with the first chamber and the at least one low-pressure port.

[0018] According some embodiments of the second aspect, the burner includes a pressure reducer between the first chamber and the second chamber, the pressure reducer configured to reduce the pressure of any fuel that flows from the first chamber to the second chamber.

[0019] According some embodiments of the second aspect, the channel in the frustoconical surface of the burner tile is configured to disrupt the flow of low-pressure fuel to increase the stability of the burner in low fire conditions.

[0020] According some embodiments of the second aspect, the plurality of fuel nozzles includes first and second high-pressure ports and first and second low-pressure ports, the first low-pressure port of each fuel nozzle configured to direct the flow of fuel from the first low-pressure port in a first direction and the second low-pressure port configured to direct the flow of fuel from the second low-pressure port in a second direction, the flow from a first low-pressure port of a first of the plurality of fuel nozzles intersecting the flow from the second low-pressure port of a second of the plurality of fuel nozzles to form a zone of low-pressure flow disruption when the fuel nozzles receive a flow of fuel.

[0021] According to a third aspect of the present disclosure, a burner tile for a burner is for receiving combustion air from a combustion air source and discharging the combustion air into a furnace space. The burner tile includes a body defining an internal passageway for conducting combustion air from a first end of the body to a second end of the body. The internal passageway defines an axis of the body. A hot face formed on the exterior of tile body. The hot face has a frustoconical outer surface, the frustoconical outer surface oriented with the smaller diameter of the frustoconical surface positioned at a second end of the burner tile. The frustoconical surface of the body includes a channel formed about the axis of the body to separate the frustoconical outer surface into an upper portion and a lower portion, the upper portion adjacent the second end of the burner tile.

[0022] In some embodiments of the third aspect, the body includes a base adjacent the first end of the body, the base having a generally cylindrical outer surface centered onthe axis of the body with a plurality of receivers formed in the cylindrical outer surface, the receivers each configured to receive a fuel nozzle.

[0023] In some embodiments of the third aspect, the body includes collar positioned on the base and the hot face is formed on the collar.

[0024] According to a fourth aspect of the present disclosure, fuel nozzle for a furnace burner includes a connector for connecting the fuel nozzle to a source of high- pressure fuel, and means for simultaneously emitting multiple streams of high-pressure fuel and multiple streams of low-pressure fuel from the fuel nozzle.

[0025] In some embodiments of the fourth aspect, the fuel nozzle includes a high- pressure chamber for receiving high-pressure fuel from the connector and a low-pressure chamber in fluid communication with the high-pressure chamber.

[0026] In some embodiments of the fourth aspect, the fuel nozzles includes a pressure reducer positioned between high-pressure chamber and low-pressure chamber.

[0027] In some embodiments of the fourth aspect, the multiple streams of low- pressure fuel are directed in divergent directions such that the streams of low-pressure fuel do not intersect.

[0028] In some embodiments of the fourth aspect, the multiple streams of low- pressure fuel are directed in divergent directions such that the streams of low-pressure fuel do not intersect.

[0029] In some embodiments of the fourth aspect, the pressure reducer comprises an orifice.

[0030] In some embodiments of the fourth aspect, the means for simultaneously emitting multiple streams of high-pressure fuel and multiple streams of low-pressure fuel from the fuel nozzle may include a fuel nozzle body having a first chamber configured to receive high-pressure fuel from a manifold. The first chamber may be configured to conduct the high-pressure fuel to a plurality of high-pressure ports that emit the high- pressure fuel from the first chamber in separate flows. The body may have a second chamber separated from the first chamber by a pressure reducer between the first chamber and the second chamber. The pressure reducer may be configured to reduce the pressureof any fuel that flows from the first chamber to the second chamber. The second chamber may be in communication with a plurality of low-pressure ports that emit the low-pressure fuel from the second chamber in separate flows.

[0031] According to a fifth aspect of the present disclosure, a method of operating a burner comprising the steps of: receiving high-pressure fuel from a fuel source into a body; separating the stream of high-pressure fuel to form a low-pressure fuel stream and a high-pressure fuel stream; emitting the low-pressure fuel stream through two ports to form divergent low-pressure flows that are directed to a slanted surface of a burner tile to form a low fire stability zone; and emitting the high-pressure fuel stream from the body through two ports to form divergent high-pressure flows that are directed above the burner tile to form a high fire stability zone.

[0032] In some embodiments of the fifth aspect, the step of separating high- pressure fuel into a low-pressure fuel stream and a high-pressure fuel stream comprises passing a portion of the high-pressure fuel through a pressure reducing orifice to form the low-pressure fuel stream.

[0033] In some embodiments of the fifth aspect, forming the low fire stability zone further includes causing the low-pressure fuel stream to intersect a low fire stability feature on the slanted surface to disrupt the flow of the low-pressure fuel streams.

[0034] In some embodiments of the fifth aspect, the method further comprises: receiving high-pressure fuel from a fuel source into a plurality of bodies; separating the stream of high-pressure fuel in each of the plurality of bodies to form a low-pressure fuel stream and a high-pressure fuel stream in each respective body; emitting the low-pressure fuel stream in each body through two ports on the respective body to form divergent low- pressure flows that are directed to a slanted surface of a burner tile to form a low fire stability zone; emitting the high-pressure fuel stream in each body through two ports on the respective body to form divergent high-pressure flows that are directed above the burner tile to form a high fire stability zone; and causing the high-pressure flows from adjacent bodies to intersect to entrain flue gasses from the burner.

[0035] In some embodiments of the fifth aspect, the method further comprises the step of: causing the low-pressure flows from adjacent bodies to intersect at the slanted surface to maintain low flame stability in on the slanted surface.

[0036] According to a sixth aspect of the present disclosure, a burner tile for a burner for receiving combustion air from a combustion air source and discharging the combustion air into a furnace space comprises a plurality of burner tile segments. The tile body segments are arranged to form a burner tile having a body that defines an internal passageway for conducting combustion air from a first end of the body to a second end of the body. A hot face is formed on the exterior of body, the hot face having a slanted outer surface oriented with a larger outer dimension positioned at a first end of the burner tile and a smaller dimension positioned at a second end of the burner tile. The slanged outer surface includes a channel formed about the outer surface to separate the outer surface into an upper portion and a lower portion, the upper portion adjacent the second end of the burner tile.

[0037] In some embodiments of the sixth aspect, the body includes a base adjacent the first end of the body, the base having a plurality of receivers formed in the outer surface, the receivers each configured to receive a fuel nozzle.

[0038] In some embodiments of the sixth aspect, the body includes a collar positioned on the base, the hot face formed on the collar.

[0039] In some embodiments of the sixth aspect, the burner tile has an elongated shape with a major axis and a minor axis.

[0040] In some embodiments of the sixth aspect, at least one of the burner tile segments is an elongated straight segment that partially defines a side wall of the burner tile.

[0041] In some embodiments of the sixth aspect, at least one of the burner tile segments is configured to form an end wall of the burner tile.

[0042] In some embodiments of the sixth aspect, at least one of the burner tile segments is configured to form a corner of the burner tile.

[0043] Additional features, which alone or in combination with any other feature(s), such as those listed above and / or those listed in the claims, can comprise patentable subject matter and will become apparent to those skilled in the art upon consideration of the following detailed description of various embodiments exemplifying the best mode of carrying out the embodiments as presently perceived.BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The detailed description particularly refers to the accompanying figures in which:

[0045] Fig. 1 is a perspective view of a burner according to the present disclosure, the burner being shown mounted to a portion of a furnace and including a fuel delivery and control system providing combustion air to a burner tile surrounded by a number of fuel nozzles;

[0046] Fig. 2 is an enlarged view of a portion of the burner of Fig. 1 to illustrate particular features in greater detail;

[0047] Fig. 3 is a perspective view of the burner tile of the burner of Fig. 1 ;

[0048] Fig. 4 is a perspective view of a fuel nozzle of Fig. 1;

[0049] Fig. 5 is a cross-sectional view of the fuel nozzle of Fig. 4 taken along lines5-5 in Fig. 4;

[0050] Fig. 6 is a cross-sectional view of the fuel nozzle of Fig. 4 taken along lines6-6 in Fig. 4;

[0051] Fig. 7 is a perspective view similar to Fig. 1, the burner in Fig. 7 being depicted with a number of fuel flows being emitted from the fuel nozzles of the burner of Fig. 1;

[0052] Fig. 8 is an enlarged view of a portion of the burner of Fig. 7 to illustrate particular features in greater detail;

[0053] Fig. 9 is cross-sectional view of a portion of the burner of Fig. 7 taken along lines 9-9;

[0054] Fig. 10 is an enlarged view of a portion Fig. 9 to illustrate particular features in greater detail;

[0055] Fig. 11 is a perspective view of an alternative embodiment of a burner tile, similar to the burner tile of Fig. 3, the burner tile of Fig. 11 having an oval shaped opening and constructed of a number of tile body segments, the tile body segments having varying geometries to allow for a burner tile to be formed in a variety of shapes; and

[0056] Fig. 12 is a perspective view of an illustrative segment of the embodiment of Fig. 11.DETAILED DESCRIPTION

[0057] A burner 10 of the present disclosure, shown in Fig. 1, is arranged to achieve internal fuel recirculation while maintaining flame stability of the burner 10. As will be described in further detail below, the flame stability is achieved by using fuel nozzles 12 that are capable of providing low-pressure stability and high-pressure firing using 100% external fuel by providing the fuel at high-pressure and low-pressure simultaneously. Flame stability is further achieved by the implementation of a burner tile 14 having a hot face 20 that is formed to include a low fire stability feature that enhances mixing of primary fuel and oxygen from a combustion air source that maintains the flame on the hot face 20 of the burner tile 14.

[0058] The burner 10 of Fig. 1 is structured to be used in typical applications and configured to be received in existing burner cutouts in a multitude of applications. As shown in Fig. 1, the burner 10 is mounted to a structure 18 of a furnace (not shown). This allows the burner 10 to be used as a replacement and improvement in existing applications, or to be used as original equipment in new applications. For example, the burner 10 could be used in coke heaters, horizontally fired platforms, crude heaters, vacuum heaters, down fired reformers for methanol, ammonia, and hydrogen, ethylene cracking furnaces, hot oil heaters, charge heaters, and reboilers, for example.

[0059] The burner 10 is similar to the COOLstar® burner available from lohn Zink Hamworthy Combustion®, using a fuel delivery and control system 16 that is known in the art. The present disclosure addresses the structure of the fuel nozzles 12 and burner tile 14 which are arranged to provide the flame stability discussed above through the delivery of both high-pressure fuel and low-pressure fuel simultaneously on the hot face 20 of theburner tile 14. The burner 10 includes a pilot 28 which provides a pilot flame for the burner 10 during normal operation.

[0060] Referring now to Figs. 2-3, the burner tile 14 has a body 22 having a base 24 and an upper collar 26 positioned on the base 24. The body 22 defines an axis 30, about which the body 22 is symmetrical. The body 22 has a first end 32 which is engaged with the fuel delivery and control system 16. A central passageway 34 is formed along the axis 30 to provide a path for combustion air to flow from the fuel delivery and control system 16 through the body 22 to exit the body 22 at a second end 36, as is known in the art.

[0061] The base 24 is adjacent the first end 32 of the body 22 and has a generally cylindrical outer surface 38 centered on the axis 30 of the body 22 with a plurality of receivers 40 formed in the cylindrical outer surface 38. The receivers 40 are embodied as longitudinal channels each configured to receive and position a fuel nozzle 12 such that the fuel nozzles 12 are equally positioned about the cylindrical outer surface 38.

[0062] The upper collar 26 is supported on the base 24 and the hot face 20 is formed on the exterior of the upper collar 26. The hot face 20 is a generally slanted surface defined by a generally frustoconical outer surface 42. The frustoconical outer surface 42 is oriented with a smaller diameter 44 of the frustoconical outer surface 42 positioned at the second end 36 of the burner tile 14. The frustoconical outer surface 42 of the body 22 is interrupted by a channel 46 formed about the axis 30 of the body 22. As will be described in more detail below, the channel 46 acts as a low fire stability feature and helps to stabilize a flame on the frustoconical outer surface 42 in high oxygen conditions at start-up of the burner 10. The channel 46 separates the frustoconical outer surface 42 into an upper portion 48 and a lower portion 50, with the upper portion 48 adjacent the second end 36 of the burner tile 14. The channel 46 of the illustrative embodiment defines a semi-circular cross-section 52 as shown in Fig. 10.

[0063] In another embodiment shown in Figs. 11 and 12, a burner tile 114 is formed from a number of discrete burner tile segments 113, 115, 116, 117, and 118. Multiple burner tile segments 113, 115, 116, 117, and 118 are arranged to form a burner tile body 122. The body 122 has a base 124 and an upper collar 126 positioned on the base 124. Thebody 122 has a first end 132 which engages with the fuel delivery and control system 16. A central passageway 134 is formed through the body 122 to provide a path for combustion air to flow from the fuel delivery and control system 16 through the body 122 to exit the body 122 at a second end 136.

[0064] The burner tile segments 115 and 116 are elongated straight segments used to form a side wall 170 of the burner tile 114 while the burner tile segment 113 forms the side wall 172. The burner tile segments 117 are curved segments that are used to establish corners of the burner tile 114. The burner tile segments 118 are straight segments that are used to form the end walls 174, 176. It should be understood that the dimensions of the various burner tile segments 115, 116, 117, and 118 may be varied as necessary to achieve the appropriate size and shape of a burner tile.

[0065] The base 124 is adjacent the first end 132 of the body 122 and has an outer surface 138 with a plurality of receivers 140 formed in the outer surface 138. The receivers 140 are embodied as longitudinal channels each configured to receive and position a fuel nozzle 12. In the embodiment of Fig. 11, the receiver 140 is formed by respective cut-outs 150, 152 formed in burner tile segments 115, 116. It should be understood that receivers 140 could also be formed at other positions along the base 124 such as shown in the embodiment of burner tile segment 119 shown in Fig. 12. The arrangement of receivers 140 may be adapted as necessary in each burner tile segment 115, 116, 117, 118, or 119 to provide an appropriate arrangement of positions for any number of fuel nozzles 112 as may be required for a particular application. Fig. 12 shows the embodiment of burner tile segment 119 shows that the burner tile segment is formed to include a receiver 40 for a fuel nozzle 12 in a centered configuration.

[0066] The upper collar 126 is supported on the base 124 and a hot face 120 is formed on the exterior of the upper collar 126. The hot face 120 is a generally slanted surface defined by an outer surface 142. The outer surface 142 is oriented such that the outer surface reduces to a smaller dimension 144 positioned at the second end 136 of the burner tile 114. Similar to the burner tile 14, the outer surface 142 of the body 122 is interrupted by a channel 46 formed in the outer surface 142.

[0067] While the operation of the burner tile 114 is similar to that of the burner tile 14, the use of the burner tile segments 115, 116, 117, 118, 119 illustrates how the structure of the burner tile 114 may be varied to achieve burner tiles of varying geometries. In the embodiment of Fig. 11, the burner tile 114 has an elongated structure with a major axis 160 and a minor axis 162. In use, the channel 46 formed in the burner tile 114 also provides the flame stability discussed above with regard to burner tile 14, regardless of the external shape of the burner tile 114.

[0068] While burner tile 114 is shown to be formed of multiple burner tile segments115, 116, 117, 118, 119, it should be understood that burner tile 114 may be formed monolithically without the use of burner tile segments 115, 116, 117, 118, 119. Various geometries of burner tiles may be used that employ the principles disclosed herein with regard to burner tiles 14 and 114. The geometry of the hot face 20, 120 with a slanted surface and the use of a structure similar to channel 46 may achieve the benefits described herein with regard to the burner tiles 14 and 114 in any of a number of geometries.

[0069] Referring now to Fig. 4, a fuel nozzle 12 is shown. The fuel nozzle 12 includes first and second high-pressure ports 60, 62, and first and second low-pressure ports 64, 66. Referring to the cross-sectional view of the fuel nozzle 12 in Fig. 5, the fuel nozzle 12 has a body 68 that is formed to include a first chamber 70 configured to receive high-pressure fuel from a manifold 72 (seen in Fig. 1) that connects to a connector 86 at a first end 74 of the fuel nozzle 12 and to provide a path for high-pressure fuel 82 to flow to and be exhausted from the high-pressure ports, 60, 62 at a second end of the fuel nozzle 12. The fuel nozzle 12 further includes a second chamber 76 in fluid communication with the first chamber 70 so that at least of a portion of the high-pressure fuel 82 in first chamber 70 flows to the second chamber 76. The body 68 of the fuel nozzle 12 is formed to include a pressure reducer 78 between the first chamber 70 and the second chamber 76. The pressure reducer 78 is configured to reduce the pressure of any fuel that flows from the first chamber 70 to the second chamber 76 such that the pressure of the fuel in the second chamber 76 is significantly lower than the manifold pressure of the fuel entering the first chamber 70. In the illustrative embodiment, the pressure reducer 78 is an orifice formedin a wall 80 between the first chamber 70 and the second chamber 76, the orifice being sized to provide an appropriate pressure drop. The low-pressure ports 64, 66 are positioned to allow low-pressure fuel 84 from the second chamber 76 to be exhausted through the low-pressure ports 64, 66 as described in further detail below.

[0070] The operation of the burner 10 may be best understood with reference to Figs. 7-10. Referring to Figs. 7-8, idealized flows of the high-pressure and low-pressure fuel streams are shown with high-pressure flows from high-pressure ports 60, 62 indicated by references Hl and H2 respectively. Similarly, the idealized flows of the low-pressure fuel flows of low-pressure ports 64, 66 are indicated by LI and L2 respectively. These idealized streams Hl, H2, LI, and L2 do not reflect the disruption of the flows that occur during actual use, but are used to establish orientation for the streams Hl, H2, LI, and L2. As can be seen in Fig. 5, the streams Hl and H2 for each fuel nozzle 12 diverge as they are directed away from each other and past the second end 36 of the burner 10 into the space where combustion air 104 is directed from the burner 10. The low-pressure streams LI, L2 for each fuel nozzle 12 diverge as they are directed away from each other and onto the lower portion 50 of the frustoconical outer surface 42. Streams Hl, H2, LI, and L2 can be considered to have respective axes 90, 92, 94, and 96 which are defined as the central axis of each of the streams Hl, H2, LI, and L2 which expand in a generally conical shape. Using a central axis 98 of each respective fuel nozzle 12, it can be seen that the axes 90, 92, 94, and 96 have compound divergence from the respective axis 98. This divergence results in the stream Hl of a first fuel nozzle 12 to intersect the stream H2 of an adjacent fuel nozzle 12 so that a disruption 100 is formed at the intersection to cause mixing of the streams Hl and H2. Similarly, the divergence of the LI and L2 streams causes the stream LI of the first fuel nozzle 12 to intersect the stream L2 of an adjacent fuel nozzle 12 so that a disruption 102 is formed at the intersection to cause mixing of the streams LI and L2.

[0071] Importantly, the disruption 102 occurs near the channel 46 which further disrupts the streams LI and L2 to improve the low flame stability of the burner 10. The low-pressure primary fuel adheres to the frustoconical outer surface 42 of the burner tile 14 to provide a constant ignition source for the burner 10. This moves the stability fromthe second end 36 of the burner 10 to the frustoconical outer surface 42 and allows for the aforementioned 100% external fuel with low-pressure stability and high-pressure firing.

[0072] The streams Hl, H2 provide high-pressure staged fuel in a high fire stability zone 106. This approach, which allows for 100% of the fuel being external to the burner tile 14 which will entrain and recirculate flue gases from the burner 10. This recirculation lowers the adiabatic flame temperature of the fuel, thereby reducing NOx emission as compared to prior art burners that do not achieve 100% external fuel. This effect, coupled with the stability of the burner 10 achieved by the configuration of the burner tile 14 with the low-pressure primary / stability fuel and a high-pressure staged fuel maximizes the NOx reduction. Thus, the present disclosure provides an improved burner 10 that is suitable for a multitude of applications and that can be used to retro-fit existing furnaces.

[0073] Although this disclosure refers to specific embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the subject matter set forth in the accompanying claims. For example, while the disclosure has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The disclosure is not limited to the disclosed embodiments. From reading the present disclosure, other modifications will be apparent to a person skilled in the art. Such modifications may involve other features, which are already known in the art and may be used instead of or in addition to features already described herein. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality.

[0074] While only certain features of the described apparatus have been illustrated and described in this application, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the invention.

[0075] The following numbered clauses include embodiments that are contemplated and non-limiting:

[0076] Clause 1. A burner comprising a burner tile and a plurality of fuel nozzles.

[0077] Clause 2. The burner of clause 1, any other clause, or any combination of clauses, wherein the burner tile has a slanted surface about a periphery of an exterior of the burner tile, the slanted surface formed to include a flow disruptor about the periphery of the burner tile, and a passageway through the interior of the burner tile for combustion air.

[0078] Clause 3. The burner of clause 2, any other clause, or any combination of clauses, wherein the plurality of fuel nozzles are positioned adjacent the burner tile, each fuel nozzle configured to be connected to a source of high-pressure fuel and to emit a low- pressure stream of fuel against the slanted surface and a high-pressure stream of fuel above the burner tile.

[0079] Clause 4. The burner of clause 3, any other clause, or any combination of clauses, wherein the slanted surface has an upper portion above the flow disruptor and a lower portion below the flow disruptor.

[0080] Clause 5. The burner of clause 4, any other clause, or any combination of clauses, wherein the low-pressure stream of fuel is directed onto the lower portion of the slanted surface.

[0081] Clause 6. The burner of clause 5, any other clause, or any combination of clauses, wherein each one of the plurality of fuel nozzles includes a first chamber and a second chamber, the second chamber separated from the first chamber by a pressure reducer.

[0082] Clause 7. The burner of clause 6, any other clause, or any combination of clauses, wherein the low-pressure stream of fuel is emitted from the second chamber.

[0083] Clause 8. The burner of clause 7, any other clause, or any combination of clauses, wherein the high-pressure stream of fuel is emitted from the first chamber.

[0084] Clause 9. The burner of clause 3, any other clause, or any combination of clauses, wherein each one of the plurality of fuel nozzles includes a first chamber and a second chamber, the second chamber separated from the first chamber by a pressure reducer.

[0085] Clause 10. The burner of clause 9, any other clause, or any combination of clauses, wherein the low-pressure stream of fuel is emitted from the second chamber.

[0086] Clause 11. The burner of clause 10, any other clause, or any combination of clauses, wherein the high-pressure stream of fuel is emitted from the first chamber.

[0087] Clause 12. The burner of clause 3, any other clause, or any combination of clauses, wherein each one of the plurality of fuel nozzles includes at least two orifices emitting independent streams low-pressure fuel and at least two orifices emitting independent high-pressure fuel.

[0088] Clause 13. The burner of clause 12, any other clause, or any combination of clauses, wherein each one of the plurality of fuel nozzles emits first and second streams of low-pressure fuel such that a first stream of low-pressure fuel from a first one of the plurality of fuel nozzles is directed to intersect a second stream of low-pressure fuel from a second one of the plurality of fuel nozzles.

[0089] Clause 14. The burner of clause 12, any other clause, or any combination of clauses, wherein each one of the plurality of fuel nozzles emits first and second streams of high-pressure fuel such that a first stream of high-pressure fuel from a first one of the plurality of fuel nozzles is directed to intersect a second stream of high-pressure fuel from a second one of the plurality of fuel nozzles.

[0090] Clause 15. The burner of clause 3, any other clause, or any combination of clauses, wherein the slanted surface has a first diameter at first end of the burner tile where the combustion air exits the burner tile and a diameter of the slanted surface increases as a distance from the first end increases.

[0091] Clause 16. A burner comprises a burner tile and a plurality of fuel nozzles.

[0092] Clause 17. The burner of clause 16, any other clause, or any combination of clauses, wherein the burner tile is attachable to a portion of a furnace compartment, the burner tile including a cylindrical inner passageway for conducting combustion air, a frustoconical exterior face having a channel formed in the frustoconical exterior face, the channel separating the frustoconical exterior face into a lower surface and an upper surface.

[0093] Clause 18. The burner of clause 17, any other clause, or any combination of clauses, wherein the plurality of fuel nozzles are positioned adjacent the burner tile, the plurality of fuel nozzles each including at least one low-pressure port and at least one high-pressure port, the at least one high-pressure port positioned to direct high-pressure combustion fuel above the cylindrical inner passageway, the at least one low-pressure port positioned to directed low-pressure combustion fuel against the lower surface of the frustoconical exterior face.

[0094] Clause 19. The burner of clause 18, any other clause, or any combination of clauses, wherein each fuel nozzle includes at least two high-pressure ports and at least two low-pressure ports.

[0095] Clause 20. The burner of clause 18, any other clause, or any combination of clauses, wherein a fuel nozzle includes a first chamber configured to receive high-pressure fuel from a manifold and to conduct the high-pressure fuel to the at least one high-pressure port.

[0096] Clause 21. The burner of clause 20, any other clause, or any combination of clauses, wherein the fuel nozzle further includes a second chamber in fluid communication with the first chamber and the at least one low-pressure port.

[0097] Clause 22. The burner of clause 21, any other clause, or any combination of clauses, wherein the burner includes a pressure reducer between the first chamber and the second chamber, the pressure reducer configured to reduce a pressure of any fuel that flows from the first chamber to the second chamber.

[0098] Clause 23. The burner of clause 18, any other clause, or any combination of clauses, wherein the channel in the frustoconical exterior face of the burner tile is configured to disrupt a flow of low-pressure fuel to increase stability of the burner in low fire conditions.

[0099] Clause 24. The burner of clause 23, any other clause, or any combination of clauses, wherein each of the plurality of fuel nozzles includes a first high-pressure port and a second high-pressure port and a first low-pressure port and a second low-pressure port, the first low-pressure port of each fuel nozzle configured to direct a flow of fuel from the first low-pressure port in a first direction and the second low-pressure port configured to direct a flow of fuel from the second low-pressure port in a second direction, the flow of fuel from the first low-pressure port of a first of the plurality of fuel nozzles intersectingthe flow of fuel from the second low-pressure port of a second of the plurality of fuel nozzles to form a zone of low-pressure flow disruption when each one of the plurality of fuel nozzles receive a flow of fuel.

[0100] Clause 25. A burner tile for a burner for receiving combustion air from a combustion air source and discharging the combustion air into a furnace space.

[0101] Clause 26. The burner tile of clause 25, any other clause, or any combination of clauses, wherein the burner tile comprises a body defining an internal passageway for conducting the combustion air from a first end of the body to a second end of the body, the internal passageway defining an axis of the body, and a hot face formed on an exterior of the body, the hot face having a frustoconical outer surface, the frustoconical outer surface oriented with the smaller diameter of the frustoconical outer surface positioned at a second end of the burner tile, the frustoconical outer surface the body including a channel formed about the axis of the body to separate the frustoconical outer surface into an upper portion and a lower portion, the upper portion adjacent the second end of the burner tile.

[0102] Clause 27. The burner tile of clause 26, any other clause, or any combination of clauses, wherein the body includes a base adjacent the first end of the body, the base having a generally cylindrical outer surface centered on the axis of the body with a plurality of receivers formed in the cylindrical outer surface, each of the plurality of receivers configured to receive a fuel nozzle.

[0103] Clause 28. The burner tile of clause 26, any other clause, or any combination of clauses, wherein the body includes a collar positioned on the base, the hot face is formed on the collar.

[0104] Clause 29. The burner tile of clause 26, any other clause, or any combination of clauses, wherein the body includes a base adjacent the first end of the body, the base having a plurality of receivers formed in the frustoconical outer surface, the each of the plurality of receivers configured to receive a fuel nozzle.

[0105] Clause 30. A fuel nozzle for a furnace burner.

[0106] Clause 31. The fuel nozzle of clause 30, any other clause, or any combination of clauses, wherein the fuel nozzle includes a connector for connecting thefuel nozzle to a source of a high-pressure fuel, and a means for simultaneously emitting multiple streams of high-pressure fuel and multiple streams of low-pressure fuel from the fuel nozzle.

[0107] Clause 32. The fuel nozzle of clause 31, any other clause, or any combination of clauses, wherein the fuel nozzle includes a high-pressure chamber for receiving the high-pressure fuel from the connector and a low-pressure chamber in fluid communication with the high-pressure chamber.

[0108] Clause 33. The fuel nozzle of clause 32, any other clause, or any combination of clauses, wherein the fuel nozzle comprises a pressure reducer positioned between the high-pressure chamber and the low-pressure chamber.

[0109] Clause 34. The fuel nozzle of clause 33, any other clause, or any combination of clauses, wherein the multiple streams of low-pressure fuel are directed in divergent directions such that the multiple streams of low-pressure fuel do not intersect.

[0110] Clause 35. The fuel nozzle of clause 34, any other clause, or any combination of clauses, wherein the multiple streams of low-pressure fuel are directed in divergent directions such that the multiple streams of low-pressure fuel do not intersect.

[0111] Clause 36. The fuel nozzle of clause 33, any other clause, or any combination of clauses, wherein the pressure reducer comprises an orifice.

[0112] Clause 37. The fuel nozzle of clause 31, any other clause, or any combination of clauses, wherein the means for simultaneously emitting the multiple streams of high-pressure fuel and the multiple streams of low-pressure fuel from the fuel nozzle comprises includes a fuel nozzle body having a first chamber configured to receive the high-pressure fuel from a manifold and to conduct the high-pressure fuel to a plurality of high-pressure ports that emit the high-pressure fuel from the first chamber in separate streams, and a second chamber separated from the first chamber by a pressure reducer between the first chamber and the second chamber, the pressure reducer configured to reduce a pressure of any fuel that flows from the first chamber to the second chamber, the second chamber in communication with a plurality of low-pressure ports that emit the multiple streams of low-pressure fuel from the second chamber in separate streams.

[0113] Clause 38. A method of operating a burner comprising the steps of: receiving a high-pressure fuel from a fuel source into a body; separating a flow of the high- pressure fuel to form a low-pressure fuel stream and a high-pressure fuel stream; emitting the low-pressure fuel stream through two ports to form divergent low-pressure flows that are directed to a slanted surface of a burner tile to form a low fire stability zone; and emitting the high-pressure fuel stream from the body through two ports to form divergent high-pressure flows that are directed above the burner tile to form a high fire stability zone.

[0114] Clause 39. The method of clause 38, any other clause, or any combination of clauses, wherein the step of separating the high-pressure fuel into the low-pressure fuel stream and the high-pressure fuel stream comprises passing a portion of the high-pressure fuel stream through a pressure reducing orifice to form the low-pressure fuel stream.

[0115] Clause 40. The method of clause 39, any other clause, or any combination of clauses, wherein forming the low fire stability zone further includes causing the low- pressure fuel stream to intersect a low fire stability feature on the slanted surface to disrupt a flow of the low-pressure fuel stream.

[0116] Clause 41. The method of clause 38, any other clause, or any combination of clauses, wherein method further comprises: receiving the high-pressure fuel from the fuel source into a plurality of bodies; separating a stream of the high-pressure fuel in each one of the plurality of bodies to form the low-pressure fuel stream and the high-pressure fuel stream in each one of the plurality of bodies; emitting the low-pressure fuel stream in each one of the plurality of bodies through the two ports on the respective body to form the divergent low-pressure flows that are directed to the slanted surface of the burner tile to form the low fire stability zone; emitting the high-pressure fuel stream in each body through the two ports on the respective body to form the divergent high-pressure flows that are directed above the burner tile to form the high fire stability zone; and causing the high- pressure fuel stream from adjacent bodies to intersect to entrain flue gasses from the burner.

[0117] Clause 42. The method of clause 41, any other clause, or any combination of clauses, wherein the method further comprises causing the low-pressure fuel streamfrom adjacent bodies to intersect at the slanted surface to maintain low flame stability in on the slanted surface.

[0118] Clause 43. The method of clause 42, any other clause, or any combination of clauses, wherein the step of separating the high-pressure fuel in each body into the low- pressure fuel stream and the high-pressure fuel stream comprises passing a portion of the high-pressure fuel through a pressure reducing orifice to form the low-pressure fuel stream in each body.

[0119] Clause 44. The method of clause 43, any other clause, or any combination of clauses, wherein forming the low fire stability zone further includes causing the low- pressure fuel flows to intersect a low fire stability feature on the slanted surface to disrupt a flow of the low-pressure fuel stream.

[0120] Clause 45. A burner tile for a burner for receiving combustion air from a combustion air source and discharging the combustion air into a furnace space.

[0121] Clause 46. The burner tile of clause 45, any other clause, or any combination of clauses, wherein the burner tile comprises a plurality of burner tile segments, the plurality of burner tile segments arranged to form the burner tile having a body that defines an internal passageway for conducting the combustion air from a first end of the body to a second end of the body, and a hot face formed on an exterior of the body, the hot face having a slanted outer surface oriented with a larger outer dimension positioned at a first end of the burner tile and a smaller dimension positioned at a second end of the burner tile, the slanted outer surface including a channel formed about the slanted outer surface to separate the slanted outer surface into an upper portion and a lower portion, the upper portion adjacent the second end of the burner tile.

[0122] Clause 47. The burner tile of clause 46, any other clause, or any combination of clauses, wherein the burner tile has an elongated shape with a major axis and a minor axis.

[0123] Clause 48. The burner tile of clause 47, any other clause, or any combination of clauses, wherein at least one of the plurality of burner tile segments is an elongated straight segment that partially defines a side wall of the burner tile.

[0124] Clause 49. The burner tile of clause 48, any other clause, or any combination of clauses, wherein at least one of the plurality of burner tile segments is configured to form an end wall of the burner tile.

[0125] Clause 50. The burner tile of clause 49, any other clause, or any combination of clauses, wherein at least one of the plurality of burner tile segments is configured to form a corner of the burner tile.

[0126] Clause 51. The burner tile of clause 47, any other clause, or any combination of clauses, wherein at least one of the plurality of burner tile segments is configured to form a corner of the burner tile.

Claims

CLAIMS1. A burner comprising: a burner tile having a slanted surface about a periphery of an exterior of the burner tile, the slanted surface formed to include a flow disruptor about the periphery of the burner tile, and a passageway through the interior of the burner tile for combustion air, and a plurality of fuel nozzles positioned adjacent the burner tile, each fuel nozzle configured to be connected to a source of high-pressure fuel and to emit a low-pressure stream of fuel against the slanted surface and a high-pressure stream of fuel above the burner tile.

2. The burner of claim 1, wherein the slanted surface has an upper portion above the flow disruptor and a lower portion below the flow disruptor.

3. The burner of claim 2, wherein the low-pressure stream of fuel is directed onto the lower portion of the slanted surface.

4. The burner of claim 3, wherein each one of the plurality of fuel nozzles includes a first chamber and a second chamber, the second chamber separated from the first chamber by a pressure reducer.

5. The burner of claim 4, wherein the low-pressure stream of fuel is emitted from the second chamber.

6. The burner of claim 5, wherein the high-pressure stream of fuel is emitted from the first chamber.

7. The burner of claim 1, wherein each one of the plurality of fuel nozzles includes a first chamber and a second chamber, the second chamber separated from the first chamber by a pressure reducer.

8. The burner of claim 7, wherein the low-pressure stream of fuel is emitted from the second chamber.

9. The burner of claim 8, wherein the high-pressure stream of fuel is emitted from the first chamber.

10. The burner of claim 1, wherein each one of the plurality of fuel nozzles includes at least two orifices emitting independent streams low-pressure fuel and at least two orifices emitting independent high-pressure fuel.

11. The burner of claim 10, wherein each one of the plurality of fuel nozzles emits first and second streams of low-pressure fuel such that a first stream of low-pressure fuel from a first one of the plurality of fuel nozzles is directed to intersect a second stream of low- pressure fuel from a second one of the plurality of fuel nozzles.

12. The burner of claim 10, wherein each one of the plurality of fuel nozzles emits first and second streams of high-pressure fuel such that a first stream of high-pressure fuel from a first one of the plurality of fuel nozzles is directed to intersect a second stream of high- pressure fuel from a second one of the plurality of fuel nozzles.

13. The burner of claim 1, wherein the slanted surface has a first diameter at first end of the burner tile where the combustion air exits the burner tile and a diameter of the slanted surface increases as a distance from the first end increases.

14. A burner comprising: a burner tile attachable to a portion of a furnace compartment, the burner tile including a cylindrical inner passageway for conducting combustion air, a frustoconicalexterior face having a channel formed in the frustoconical exterior face, the channel separating the frustoconical exterior face into a lower surface and an upper surface; a plurality of fuel nozzles positioned adjacent the burner tile, the plurality of fuel nozzles each including at least one low-pressure port and at least one high-pressure port, the at least one high-pressure port positioned to direct high-pressure combustion fuel above the cylindrical inner passageway, the at least one low-pressure port positioned to directed low-pressure combustion fuel against the lower surface of the frustoconical exterior face.

15. The burner of claim 14, wherein each fuel nozzle includes at least two high-pressure ports and at least two low-pressure ports.

16. The burner of claim 14, wherein a fuel nozzle includes a first chamber configured to receive high-pressure fuel from a manifold and to conduct the high-pressure fuel to the at least one high-pressure port.

17. The burner of claim 16, wherein the fuel nozzle further includes a second chamber in fluid communication with the first chamber and the at least one low-pressure port.

18. The burner of claim 17, wherein the burner includes a pressure reducer between the first chamber and the second chamber, the pressure reducer configured to reduce a pressure of any fuel that flows from the first chamber to the second chamber.

19. The burner of claim 14, wherein the channel in the frustoconical exterior face of the burner tile is configured to disrupt a flow of low-pressure fuel to increase stability of the burner in low fire conditions.

20. The burner of claim 19, wherein each of the plurality of fuel nozzles includes a first high-pressure port and a second high-pressure port and a first low-pressure port and a second low-pressure port, the first low-pressure port of each fuel nozzle configured todirect a flow of fuel from the first low-pressure port in a first direction and the second low- pressure port configured to direct a flow of fuel from the second low-pressure port in a second direction, the flow of fuel from the first low-pressure port of a first of the plurality of fuel nozzles intersecting the flow of fuel from the second low-pressure port of a second of the plurality of fuel nozzles to form a zone of low-pressure flow disruption when each one of the plurality of fuel nozzles receive a flow of fuel.

21. A burner tile for a burner for receiving combustion air from a combustion air source and discharging the combustion air into a furnace space, the burner tile comprising a body defining an internal passageway for conducting the combustion air from a first end of the body to a second end of the body, the internal passageway defining an axis of the body, and a hot face formed on an exterior of the body, the hot face having a frustoconical outer surface, the frustoconical outer surface oriented with the smaller diameter of the frustoconical outer surface positioned at a second end of the burner tile, the frustoconical outer surface the body including a channel formed about the axis of the body to separate the frustoconical outer surface into an upper portion and a lower portion, the upper portion adjacent the second end of the burner tile.

22. The burner tile of claim 21, wherein the body includes a base adjacent the first end of the body, the base having a generally cylindrical outer surface centered on the axis of the body with a plurality of receivers formed in the cylindrical outer surface, each of the plurality of receivers configured to receive a fuel nozzle.

23. The burner tile of claim 21, wherein the body includes a collar positioned on the base, the hot face is formed on the collar.

24. The burner tile of claim 21, wherein the body includes a base adjacent the first end of the body, the base having a plurality of receivers formed in the frustoconical outer surface, the each of the plurality of receivers configured to receive a fuel nozzle.

25. A fuel nozzle for a furnace burner, the fuel nozzle including a connector for connecting the fuel nozzle to a source of a high-pressure fuel, and a means for simultaneously emitting multiple streams of high-pressure fuel and multiple streams of low-pressure fuel from the fuel nozzle.

26. The fuel nozzle of claim 25, wherein the fuel nozzle includes a high-pressure chamber for receiving the high-pressure fuel from the connector and a low-pressure chamber in fluid communication with the high-pressure chamber.

27. The fuel nozzle of claim 26, comprising a pressure reducer positioned between the high-pressure chamber and the low-pressure chamber.

28. The fuel nozzle of claim 27, wherein the multiple streams of low-pressure fuel are directed in divergent directions such that the multiple streams of low-pressure fuel do not intersect.

29. The fuel nozzle of claim 28, wherein the multiple streams of low-pressure fuel are directed in divergent directions such that the multiple streams of low-pressure fuel do not intersect.

30. The fuel nozzle of claim 27, wherein the pressure reducer comprises an orifice.

31. The fuel nozzle of claim 25, wherein the means for simultaneously emitting the multiple streams of high-pressure fuel and the multiple streams of low-pressure fuel from the fuel nozzle comprises includes a fuel nozzle body having a first chamber configured toreceive the high-pressure fuel from a manifold and to conduct the high-pressure fuel to a plurality of high-pressure ports that emit the high-pressure fuel from the first chamber in separate streams, and a second chamber separated from the first chamber by a pressure reducer between the first chamber and the second chamber, the pressure reducer configured to reduce a pressure of any fuel that flows from the first chamber to the second chamber, the second chamber in communication with a plurality of low-pressure ports that emit the multiple streams of low-pressure fuel from the second chamber in separate streams.

32. A method of operating a burner comprising the steps of: receiving a high-pressure fuel from a fuel source into a body; separating a flow of the high-pressure fuel to form a low-pressure fuel stream and a high-pressure fuel stream; emitting the low-pressure fuel stream through two ports to form divergent low- pressure flows that are directed to a slanted surface of a burner tile to form a low fire stability zone; and emitting the high-pressure fuel stream from the body through two ports to form divergent high-pressure flows that are directed above the burner tile to form a high fire stability zone.

33. The method of claim 32, wherein the step of separating the high-pressure fuel into the low-pressure fuel stream and the high-pressure fuel stream comprises passing a portion of the high-pressure fuel stream through a pressure reducing orifice to form the low- pressure fuel stream.

34. The method of claim 33, wherein forming the low fire stability zone further includes causing the low-pressure fuel stream to intersect a low fire stability feature on the slanted surface to disrupt a flow of the low-pressure fuel stream.

35. The method claim 32, wherein method further comprises:receiving the high-pressure fuel from the fuel source into a plurality of bodies; separating a stream of the high-pressure fuel in each one of the plurality of bodies to form the low-pressure fuel stream and the high-pressure fuel stream in each one of the plurality of bodies; emitting the low-pressure fuel stream in each one of the plurality of bodies through the two ports on the respective body to form the divergent low-pressure flows that are directed to the slanted surface of the burner tile to form the low fire stability zone; emitting the high-pressure fuel stream in each body through the two ports on the respective body to form the divergent high-pressure flows that are directed above the burner tile to form the high fire stability zone; and causing the high-pressure fuel stream from adjacent bodies to intersect to entrain flue gasses from the burner.

36. The method of claim 35, further comprising the step of: causing the low-pressure fuel stream from adjacent bodies to intersect at the slanted surface to maintain low flame stability in on the slanted surface.

37. The method of claim 36, wherein the step of separating the high-pressure fuel in each body into the low-pressure fuel stream and the high-pressure fuel stream comprises passing a portion of the high-pressure fuel through a pressure reducing orifice to form the low-pressure fuel stream in each body.

38. The method of claim 37, wherein forming the low fire stability zone further includes causing the low-pressure fuel flows to intersect a low fire stability feature on the slanted surface to disrupt a flow of the low-pressure fuel stream.

39. A burner tile for a burner for receiving combustion air from a combustion air source and discharging the combustion air into a furnace space, the burner tile comprising:a plurality of burner tile segments, the plurality of burner tile segments arranged to form the burner tile having a body that defines an internal passageway for conducting the combustion air from a first end of the body to a second end of the body, and a hot face formed on an exterior of the body, the hot face having a slanted outer surface oriented with a larger outer dimension positioned at a first end of the burner tile and a smaller dimension positioned at a second end of the burner tile, the slanted outer surface including a channel formed about the slanted outer surface to separate the slanted outer surface into an upper portion and a lower portion, the upper portion adjacent the second end of the burner tile.

40. The burner tile of claim 39, wherein the burner tile has an elongated shape with a major axis and a minor axis.

41. The burner tile of claim 40, wherein at least one of the plurality of burner tile segments is an elongated straight segment that partially defines a side wall of the burner tile.

42. The burner tile of claim 41, wherein at least one of the plurality of burner tile segments is configured to form an end wall of the burner tile.

43. The burner tile of claim 42, wherein at least one of the plurality of burner tile segments is configured to form a corner of the burner tile.

44. The burner tile of claim 40, wherein at least one of the plurality of burner tile segments is configured to form a corner of the burner tile.

Images