Burner block assembly for an industrial furnace

Abstract

An industrial furnace burner block assembly is presented herein. The assembly includes a mounting plate defining a fire tube extending there from. A plurality of tabs extend from the mounting plate and engage a corresponding groove or slot formed on a refractory burner block. The burner block includes four block sections that each allow for independent thermal growth during operation. The burner block also defines a center aperture collectively formed by corresponding internal surfaces of the independent block sections. A sealing ring is mounted within a groove in the burner aperture and is disposed in a sealing relation with an external surface of the firing tube. A tongue-and-groove connection assembly is formed on mating surfaces between adjacent burner block sections. The tongue-and-groove connection assembly and the sealing ring each provide a gas-tight seal that restricts gas bypassing.

Claims

1. A burner block assembly, comprising: a mounting plate comprising a first surface and a second surface, a burner port extending from said first surface, an attachment assembly fixed to said mounting plate and extending from said first surface, a burner block mounted to said mounting plate via said attachment assembly, said burner block comprising a plurality of independent block sections, each of said plurality of independent block sections comprising an internal surface, wherein said internal surfaces of said plurality of independent block sections collectively define a burner block aperture, said burner block aperture being disposed in a surrounding relation to said burner port, each of said plurality of independent block sections further comprising a groove disposed on an internal surface, and a sealing member mounted within said burner block aperture and within said groove of each of said plurality of independent block sections, and disposed in an engaging relation to an external surface of said burner port.

2. The assembly as recited in claim 1 wherein said groove is orthogonal to a burner port axis.

3. The assembly as recited in claim 2 wherein said sealing member comprises a resilient member mounted within said groove and extending to said external surface of said burner port.

4. The assembly as recited in claim 3 wherein said sealing member restricts gas bypassing between said burner block and said burner port.

5. The assembly as recited in claim 1 wherein each of said independent block sections comprise an external attachment groove disposed on at least one external surface.

6. The assembly as recited in claim 5 wherein said attachment assembly comprises a plurality of clips extending from said first surface of said mounting plate, wherein each of said plurality of clips attach to at least one of said plurality of independent block sections at a corresponding one of said external attachment grooves.

7. The assembly as recited in claim 6 wherein each of said plurality of clips comprise an arm attached to said mounting plate and an angled projection extending from a distal end of said arm, said angled projection being disposed within said corresponding one of said external attachment grooves of said at least one of said plurality of independent block sections.

8. The assembly as recited in claim 1 wherein each of said plurality of independent block sections comprise at least one mating surface, wherein said mating surfaces of adjacent ones of said plurality of independent block sections mate against each other.

9. The assembly as recited in claim 8 wherein a first one of said mating surfaces of adjacent ones of said plurality of independent block sections comprises a tongue and wherein a second one of said mating surfaces of adjacent ones of said plurality of independent block sections comprises a groove, wherein said tongue and said groove connect with one another.

10. The assembly as recited in claim 9 wherein said tongue extends to and between opposing edges of said first one of said mating surfaces and said groove extends to and between opposing edges of said second one of said mating surfaces.

11. The assembly as recited in claim 10 wherein said tongue and said groove restrict gas bypassing between said adjacent ones of said plurality of independent block sections.

12. The assembly as recited in claim 1 further comprising at least one insulation layer disposed between said mounting plate and said burner block to reduce a thermal profile on said mounting plate.

13. The assembly as recited in claim 12 wherein said at least one insulation layer comprises a first insulation layer and a second insulation layer, said second insulation layer stacked on top of said first insulation layer, wherein said first insulation layer comprises at least two sections connected to one another at at least one first joint, and wherein said second insulation layer comprises at least two sections connected to one another at at least one second joint, said at least one second joint being offset from said at least one first joint.

14. A burner block assembly, comprising: a mounting plate comprising a first surface and a second surface, a fire tube extending from said first surface of said mounting plate, an attachment assembly comprising a plurality of clips extending from said first surface of said mounting plate, a burner block mounted to said mounting plate via said attachment assembly, said burner block comprising a plurality of independent block sections, each of said plurality of independent block sections comprises an external attachment groove disposed on at least one external surface, wherein each of said plurality of clips attach to at least one of said plurality of independent block sections at a corresponding one of said external attachment grooves, said burner block further comprising an aperture collectively defined by internal surfaces of said plurality of independent block sections, said aperture being disposed in a surrounding relation to said fire tube, each of said plurality of independent block sections further comprise a groove disposed on at least a corresponding one of said internal surfaces, a sealing member mounted within said groove of each of said plurality of independent block sections and disposed in a sealing relation to an external surface of said burner port, each of said plurality of independent block sections comprise at least one mating surface with one portion of a tongue-and-groove assembly that corresponds with a mating surface of an adjacent one of said plurality of independent block sections with another portion of said tongue-groove-assembly.

15. The assembly as recited in claim 14 wherein said burner block comprises four substantially geometrically symmetrical independent block sections.

16. The assembly as recited in claim 15 wherein each of said four substantially geometrically symmetrical independent block sections are independently thermally expansible.

17. The assembly as recited in claim 16 wherein said sealing member restricts gas bypassing between said burner block and said burner port, and to said mounting plate.

18. The assembly as recited in claim 17 wherein said tongue-and-groove assembly restricts gas bypassing between adjacent ones of said plurality of independent block sections.

19. The assembly as recited in claim 18 further comprising at least one insulation layer disposed between said mounting plate and said burner block to reduce a thermal profile on said mounting plate.

20. A burner block assembly, comprising: a mounting plate comprising a first surface and a second surface, a burner port extending from said first surface, an attachment assembly fixed to said mounting plate and extending from said first surface, a burner block mounted to said mounting plate via said attachment assembly, said burner block comprising a plurality of independent block sections, each of said plurality of independent block sections comprising an internal surface, wherein said internal surfaces of said plurality of independent block sections collectively define a burner block aperture, said burner block aperture being disposed in a surrounding relation to said burner port, a sealing member mounted within said burner block aperture and disposed in an engaging relation to an external surface of said burner port, at least one insulation layer disposed between said mounting plate and said burner block to reduce a thermal profile on said mounting plate, wherein said at least one insulation layer comprises a first insulation layer and a second insulation layer, said second insulation layer stacked on top of said first insulation layer, wherein said first insulation layer comprises at least two sections connected to one another at at least one first joint, and wherein said second insulation layer comprises at least two sections connected to one another at at least one second joint, said at least one second joint being offset from said at least one first joint.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a front perspective view of the burner block assembly as disclosed in at least one embodiment of the present invention.

(2) FIG. 2 is an exploded perspective view of the burner block assembly illustrated in FIG. 1.

(3) FIG. 3 is a perspective view of the refractory burner block as disclosed in accordance with at least one embodiment of the present invention.

(4) FIG. 4A is a cross-sectional view of the refractory burner block along line 4A-4A shown in FIG. 3.

(5) FIG. 4B is a cross-sectional view of the refractory burner block along line 4B-4B shown in FIG. 3.

(6) FIG. 4C is a cross-sectional view of the refractory burner block along line 4C-4C shown in FIG. 3.

(7) FIG. 4D is a cross-sectional view of the refractory burner block along line 4D-4D shown in FIG. 3.

(8) FIG. 5 is a side elevation view of the mounting plate as disclosed in accordance with at least one embodiment of the present invention.

(9) FIG. 6 is a plan view of the sight port cover as disclosed in accordance with at least one embodiment of the present invention.

(10) FIG. 7 is a top plan view of the mounting plate as disclosed in accordance with at least one embodiment of the present invention.

(11) Like reference numerals refer to like parts throughout the several views of the drawings provided herein.

DETAILED DESCRIPTION OF THE INVENTION

(12) As shown in the accompanying drawings, and with particular reference to FIG. 1, at least one embodiment of the present invention is generally directed to a burner block assembly (sometimes also referred to as a burner tile or burner quarl), referenced as 10 throughout the figures, that is configured for use in high-temperature industrial furnaces, kilns, incinerators, reactors, etc. (collectively referred to herein as a furnace or furnaces.)

(13) In particular, the burner block assembly 10 of at least one embodiment of the present invention includes a mounting plate or base 20, upon which the burner block 40 is mounted, either directly or indirectly. The mounting plate 20 of at least one embodiment may be constructed of carbon steel or other rigid, durable material that is able to withstand the high temperatures of the furnace and environment.

(14) Moreover, the mounting plate 20 includes a first surface 22a and a second surface 22b. The first surface 22a, in some instances, faces towards the combustion chamber of the furnace (not shown), while the second surface 22b faces away from the combustion chamber. In this manner, the first and second surfaces 22a, 22b are opposite one another, and as shown the exemplary embodiment of the drawings (e.g., with reference to FIGS. 1 and 5), may include generally flat or planar surfaces. It should be noted, however, that in other embodiments, one or both of the opposing first and second surfaces 22a, 22b of the mounting plate 20 may be non-planar, for example, with one or more curves, contours, angles, steps, etc.

(15) With reference now to FIGS. 2 and 5, the mounting plate 20, of at least one embodiment, also includes a burner port or firing tube 24 that extends from the first surface 22a or other surface of the mounting plate 20. More in particular, the burner port or firing tube 24 defines an aperture or internal cavity 25 that passes through the burner port 24 and terminates at opposing open ends 25a, 25b. A fuel (e.g., gas or natural gas) and/or an oxidant may be supplied at one end 25b of the cavity or aperture 25 while the combustion, heat or ignition passes through the other end 25a of the cavity or aperture 25 (e.g., at a hot end of the burner block 40) and into the combustion zone of the furnace (not shown).

(16) Furthermore, as shown in FIGS. 1, 2, 5 and 7, the mounting plate 20 of at least one embodiment also includes an attachment assembly 30 that is used to mount or attach a burner block 40 thereto, as discussed herein. The attachment assembly 30 and/or at least a portion of the attachment assembly 30 may be fixed or otherwise connected, either movably, removably or non-movably, to the mounting plate 20 and, in at least one embodiment, extends from (e.g., upward or outward from) the first surface 22a thereof.

(17) In particular, the attachment assembly 30, of at least one embodiment, includes at least one, although in many embodiments a plurality of extensions, tabs or clips, referenced as 32 extending from the mounting plate 20, e.g., from the first surface 22a thereof, and are attachable to the burner block 40. In some cases, at least one or all of the clips, tabs or extensions 32 may include an arm 34 that attaches at one end to the mounting plate 20 and which include an angled projection 36 or mounting finger at the other, distal end. As will be described herein, the angled projection 36 of the clip or extension 32 will attach or engage to a corresponding groove 71-74 or other like structure, mechanism or component of the burner block 40.

(18) With reference now to FIG. 5, at least one or all of the tabs or clips 32 of the attachment assembly 30, and in particular the arms 34 thereof, may be orthogonal or perpendicular, or substantially orthogonal or perpendicular to the first surface 22a of the mounting plate 20, although other configurations are contemplated within the full spirit and scope of the present invention.

(19) Referring again to FIG. 1, as well as FIGS. 2-5, a burner block 40 is mounted to the mounting plate 20 via the attachment assembly 30. As provided above, the burner block 40 may be constructed of a refractory material that is resistant to the high temperatures generated in the furnace, and can include a material that is resistant to thermal shock, may be chemically inert, and may have particular ranges of thermal conductivity and thermal expansion.

(20) In any event, the burner block 40 of at least one embodiment includes a plurality of block sections, referenced as 41, 42, 43, 44 in the exemplary embodiment shown in the figures, each of which mate with or against one or more adjacent block sections to collectively define the burner block 40.

(21) More specifically, in at least one embodiment, each of the block sections 41, 42, 43, 44 include an internal surface 41a, 42a, 43a, 44a or an inside-facing surface that defines a portion of a burner block aperture 45. The burner block aperture 45 is an opening or hole through the burner block 40, sometimes although not always, through the center of the burner block 40, and corresponds with or communicates with the burner port or firing tube 24, and in particular, the aperture 25 thereof. In some embodiments, the burner block aperture 45 is disposed in a surrounding relation to the firing tube 24.

(22) Furthermore, with reference to FIGS. 1-3, the internal surfaces 41a, 42a, 43a, 44a in the embodiment shown are curved or rounded such that collectively, the internal surfaces 41a, 42a, 43a, 44a define a circular aperture 45. However, other embodiments are not limited to such a shape or configuration in that that aperture 45 may be virtually any shape including oval or elliptical, square, rectangular, or other polygon or shape.

(23) Moreover, each of the block sections 41-44 include at least one, although more commonly, two mating surfaces that face, engage or mate against corresponding mating surfaces of an adjacently disposed block section.

(24) More specifically, in the embodiment illustrated in FIGS. 1-3, as well as FIGS. 4A-4B, block section 41 includes two mating surfaces 41b, 41c; block section 42 includes two mating surfaces 42b, 42c; block section 43 includes two mating surfaces 43b, 43c; and block section 44 includes two mating sections 44b, 44c. Furthermore, mating surface 41b faces, engages or mates against adjacent mating surface 44b; mating surface 41c faces, engages or mates against adjacent mating surface 42c; mating surface 42b faces, engages or mates against adjacent mating surface 43b; mating surface 42c faces, engages or mates against adjacent mating surface 41c; mating surface 43b faces, engages or mates against adjacent mating surface 42b; mating surface 43c faces, engages or mates against adjacent mating surface 44c; mating surface 44b faces, engages or mates against adjacent mating surface 41b; and mating surface 44c faces, engages or mates against adjacent mating surface 43c. Other shapes and configurations of the burner block 40 and the sections thereof 41-44 are contemplated.

(25) Additionally, in at least one embodiment the mating surfaces of the burner block sections 41-44 include a connection assembly, for example, in the form of corresponding tongues-and-grooves in order to facilitate the mating or interconnection between adjacent mating surfaces and/or the burner block sections 41-44. For example, a first one of the mating surfaces of adjacent block sections includes a tongue or projection, while the other one or the second one of the mating surfaces of adjacent block sections includes a groove, such that, the tongue and the groove connect or mate with one another. In other words, each pair of adjacently disposed mating surfaces (of adjacent block sections) may include a tongue-and-groove connection assembly facilitating the interconnection or mating there between.

(26) As an example, with reference to the embodiment shown in FIGS. 1-3, mating surface 41b of section 41 includes a groove 51b which corresponds and connects with tongue or projection 54b on adjacent mating surface 44b; mating surface 41c of section 41 includes a groove 51c which corresponds and connects with tongue or projection 52c on adjacent mating surface 42c; mating surface 42b of section 42 includes a tongue or projection 52b which corresponds and connects with groove 53b on adjacent mating surface 43b; and mating surface 43c of section 43 includes a groove 53c which corresponds and connects with tongue or projection 54c on adjacent mating surface 44b.

(27) Of course, other tongue-and-groove configurations (e.g., the reverse of that described above) as well as other connection assemblies, such as clips, clamps, hooks, loops, etc. is/are also contemplated within the full spirit and scope of the present invention.

(28) Furthermore, in at least one embodiment, the tongues and grooves of the tongue-and-groove connection assembly extend to and between opposing edges of the corresponding mating surface. For example, with reference to FIG. 4A, groove 51b on surface 41b extends all the way to and between the opposing edges 61a, 61b. In this example, hole or sight port 90 extends through the block section 41 transverse to the groove 51b, but otherwise, the groove 51b extends to the opposing edges 61a, 61b and entirely there between. Further, groove 51c extends to opposing edges 61c, 61d and entirely therebetween. Tongue or projection 52c extends to and entirely between edges 62c, 62d; tongue or projection 52b extend to opposing edges 62a, 62 and entirely there between; groove 53b extends to opposing edges 63a, 63b, and entirely there between; groove 53c extend to opposing edges 63c, 63d and entirely there between; tongue or projection 54c extends to opposing edges 64c, 64 and entirely there between; and tongue 54b extends to opposing edges 64a, 64b and entirely there between, although in the example shown, hole or sight port 90 extends transversely across tongue 54b.

(29) Moreover, the tongue-and-groove design or connection assembly between adjacent burner block sections 41-44 restricts gas bypassing between each of the block sections 41-44. In other words, the large radius design of the tongue and/or groove allows the surface areas of each block section 41-44 to provide a gas-tight or gas-restricting seal, even in the event the burner tip is firing directly onto a burner block section 41-44 with flame impingement. This scaling effect of the joint between adjacent burner block sections 41-44 restricts, and in some cases eliminates gas bypassing to the shell.

(30) Furthermore, in at least one embodiment, at least one, although in many embodiments, each of the burner block sections 41-44 include an internal groove 71, 72, 73, 74 within which a sealing member 70 is disposed. In some embodiments, for example, as shown in the example of FIGS. 4A and 4B, the grooves 71-74 are orthogonal to or otherwise perpendicular to a burner port axis A. Other orientations are contemplated, however.

(31) In any case, the sealing member 70 of at least one embodiment is a scaling ring that is disposed, seated or sealed within the corresponding grooves 71-74, and encircles, surrounds and in some cases sealingly engages to an external surface of the burner port or firing tube 24. In this manner, the gas sealing ring 70 disposed on or sealingly engaged to the external surface or circumference of the firing tube 24 restricts, and in some cases eliminates gas bypassing between the burner block 40 and the firing tube 24. For instance, the gas sealing ring 70 of at least one embodiment is configured to restrict or eliminate all gas bypassing back to the mounting plate 20.

(32) More specifically, the gas sealing member or ring 70 of at least one embodiment is constructed of a heat-resistant and in some cases rigid or semi-rigid material, such as but in no way limited to stainless steel, although other materials are contemplated such that the gas sealing member 70 operates in the intended fashion to restrict the flow of gas there through during operation of the burner block assembly 10. Moreover, in at least one embodiment, when the burner block 40 or burner block sections 41-44 are set in place, the slot(s) 71-74 within which the sealing ring 70 is seated may be filled with mortar or other like material.

(33) It should also be noted that, simply for purposes of clarity and illustration, the size, dimensions and or thicknesses of the sealing ring 70, as well as other components and features of the various embodiments, shown in the Figures, and in particular, the cut-away views of FIGS. 4A-4D, may not be drawn or shown to scale.

(34) Furthermore, in at least one embodiment, at least one, although in most cases each of the plurality of burner block sections 41-44 includes a groove 81, 82, 83, 84 such as an attachment groove disposed on an external surface or otherwise accessible externally from the burner block 40. The grooves 81-84 or channels are formed to correspondingly receive the clips 32 of the attachment assembly 30 therein. In other words, the angled tips or ends 36 of the clips 32 connect to or are otherwise removably disposed within the corresponding groove(s) 81-84 in order to mount the burner block 40 to the mounting plate 20.

(35) In at least one embodiment, the each of the grooves 81-84 include a recessed lower ledge 81a, 82a, 83a, 84a that extends downward from the outer opening of the groove or channel 81-84. More specifically, the lower ledges 81a, 82a, 83a, 84a of at least one embodiment is recessed inward from the corresponding outer edges or wall and is, therefore, considered recessed. The ledge or wall 81a, 82a, 83a, 84a may be recessed a distance approximately equal to a thickness of the clip arm 34, although other recessed distances, as well as no recess is contemplated.

(36) Furthermore, in at least one embodiment, the external grooves 81, 82, 83, 84, and in some cases, the recessed ledges or walls 81a, 82a, 83a, 84a may continuously extend the entire periphery of the burner block 40. In other embodiments, however, the external grooves 81, 82, 83, 84 and/or the recessed ledges or walls 81a, 82a, 83a, 84a may be positioned on the burner block 40 and/or the sections 41-44 thereof in order to correspond with the positioning of the clips 32 that extend from the mounting plate 20.

(37) Moreover, the individual mounting tabs or clips 32 of at least one embodiment and the corresponding channels 81-84 allow each of the burner block sections 41-44 to move independently of one another, thereby reducing stress during thermal cycling. In this manner, each of the burner block sections 41-44 are referred to herein as being independent and/or separate.

(38) More specifically, it should also be noted that anchor embedment is often a cause for concern due to the different in thermal expansion coefficients between embedded alloy anchor and the refractory material. As described herein, at least one embodiment uses at least one, although more practically a plurality of attachment clips or tabs 32 that mount into a joint, groove or channel 81-8814 fabricated into the refractory material. This allows the anchoring system, attachment assembly 30 and/or the burner block 40 itself to expand without affecting the integrity of the refractory block 40.

(39) Additionally, the reduction of the mechanical stress on the clips or tabs 32 eliminates breaking or weld cracking failures. The angled tabs 32 also allow the burner block 40 and/or the sections 41-44 thereof to be attached to the shell via a cast slot in the refractory shape. This attachment allows for a tight installation of the block to the shell without the use of bolting or refractory anchors.

(40) Furthermore, in at least one embodiment, and in particular as shown in FIGS. 1-3, the burner block 40 includes four substantially geometrically symmetrical independent block sections 41-44. More specifically, the block sections 41-44 may not be perfectly geometrically symmetrical due to the tongue-and-groove connection assembly described herein and/or the hole or sight port 90 formed through the burner block 40. In any event, the four block sections 41-44 provides a four-quadrant block fabrication. Each block section 41-44 forms an outer corner of the square, rectangular or polygonal shape of the burner block 40, and includes an inner radial wall that collectively forms the burner block aperture 45.

(41) The four-block design of at least one embodiment of the present invention allows for the independent thermal growth of each block section 41-44. In other words, one block section may thermally expand or grow at a different rate or impact than another one of the block sections of the same burner block 40. This reduces internal mechanical stresses and prevents or minimizes cracking of refractory shapes.

(42) In addition, the independent and separate burner block shapes of at least one embodiment of the present invention reduces stress on the attachment assembly 30, that in turn, reduces or eliminate warping of the mounting plate that would then lead to gas bypassing on the carbon steel shell.

(43) Moreover, the geometric symmetry or substantial geometric symmetry of the four block assembly of at least one embodiment allows for a more uniform equilibrium of the entire assembly 10. With each quadrant or block section performing independently and the same as the other block sections, mechanical stresses are not localized, and stresses that may be applied to the firing tube and/or mounting plate are reduced or eliminated.

(44) It should also be noted that with separate and independent block sections, each section 41-44 can be repaired or replaced without having to repair or replace the other section(s). In other words, one section or quadrant can be replaced or repaired without affecting the other block sections or other components of the assembly 10.

(45) Further, the designed refractory materials of construction provide an assembly 10 that allows for controlled expansion while reducing the mounting plate temperature. The assembly 10 provides for mechanical abuse and flame impingement of burner while controlling expansion to reduce mechanical stress on the burner block attachment tabs 32.

(46) Referring again to FIGS. 1 and 2, in at least one embodiment the assembly 10 also includes at least one intermediate plate or insulation layer, such as a first intermediate layer 12 and a second intermediate layer 14 disposed between the mounting plate 20 and the burner block 40. In the example shown, the first and second layers 12, 14 are stacked upon one another, with the first layer engaging or facing the mounting plate 20 and the second layer engaging or facing the burner block 40. In other embodiments, more or less than two intermediate or insulation layers 12, 14 are contemplated. In any event, the one or more intermediate or insulation layers 12, 14 provide one or more layers of insulation or protection that reduces the thermal profile of the hot face temperature across the mounting plate. This reduces or restricts warping of the mounting plate 20 that can otherwise occur if the temperature of mounting plate 20 or the temperature upon which the mounting plate 20 is exposed is too high. In this manner, the one or more layers 12, 14 of at least one embodiment may be constructed of any material configured to facilitate implementation of the present invention in the intended manner, including, for example, heat-resistant materials, rigid board insulation material, or other rigid, semi-rigid or resilient and durable material that is able to withstand the high temperatures of the furnace and environment. Furthermore, in some embodiments, the insulation layer(s) 12, 14 may be approximately one and half inches in thickness each. Thus, in the embodiment with two insulation layers 12, 14, a total of approximately three inches of insulation may be provided. Of course, other embodiments may have more or fewer than two insulation layers, and each insulation layer may have a thickness of more or less than one and a half inches.

(47) Moreover, as shown in FIGS. 1 and 2, for example, the intermediate plates or insulation layers 12, 14 each include center holes or openings 13a, 15a that correspond with or otherwise receive the burner port 24 therethrough, and which correspond or at least partially align with the burner block aperture 45.

(48) Furthermore, at least one secondary hole 13b, 15b may also be included to correspond or at least partially align with the sight port 90 formed on the burner block 40.

(49) Moreover, in at least one embodiment, at least one of the intermediate plates or layers, such as the first intermediate plate 12 includes one or more openings, grooves or recesses, referenced as 17a-c, which correspond with one or more tabs or projections, referenced as 16a-c disposed on the mounting plate 20. In other words, the tabs or projections 16a-c on the mounting plate 20 will line up with and connect to the corresponding openings, grooves or recesses 17a-c on the intermediate plate 12. This allows the intermediate plate to be properly aligned and mounted to the mounting plate 20.

(50) Furthermore, in at least one embodiment, each of the two layers 12, 14 may be in at least two pieces or sections that are joined at corresponding joint. For example, in the embodiment shown, the first intermediate plate 12 may include at least two, although in this example, four sections referenced as 12a-d connected to one another along corresponding joints 12c-h. Similarly, the second intermediate plate 14 may also include at least two, although in this example, four sections referenced as 14a-d connected to one another along corresponding joints 14c-h. In at least one embodiment, when the two plates 12, 14 are stacked upon one another or layered in the manner shown, the at least two joints 12e-h on one layer 12 are offset from, or otherwise do not line up with the at least two joints 14e-h of the other layer 14. This provides some additional structural integrity to the plates 12, 14 and to the assembly 10 as a whole and also restricts or eliminates any clear through path from the joints within which heat would otherwise pass.

(51) FIG. 6 illustrates an exemplary sight port cover 95 mounted to the second surface 22b of the mounting plate 20, as shown in FIG. 5, for example, via one or more fasteners (not shown. The sight port cover 95 can be selectively disposed between a closed position and an open position. More specifically, when the sight port cover 95 is disposed in the closed position, the cover 95 obstructs or overlies a sight port that passes through the mounting plate 20 and the burner block 40 via hole 21 (in the mounting plate 20) and hole or sight port 90 (in the burner block 40). In the event one or more intermediate or insulation layers 12, 14 are used, corresponding holes 13b, 15b also align to collectively form the sight port. In order to open the sight port, the sight port cover 95 can be moved, pivoted, slid or swung into a position that exposes the hole 21 and the remaining sight port. This can be done, in some cases, by loosening or removing one the fasteners that secures the sight port cover 95 in place, although other embodiments allow for other methods of moving the sight port cover 95 into and out of the closed and open position. With the sight port cover 95 in the open position, an operator or user can obtain a visual view from the exterior side of the furnace or from the second side 22b of the mounting plate 20 through the insulation layer(s) 12, 14 (if present) and through the burner block 40 in order to view or inspect the flame ignition or burner tip.

(52) Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention. This written description provides an illustrative explanation and/or account of the present invention. It may be possible to deliver equivalent benefits using variations of the specific embodiments, without departing from the inventive concept. This description and these drawings, therefore, are to be regarded as illustrative and not restrictive.