Surface Combustion Burner

Abstract

To provide a surface combustion burner which can improve the durability of a discharge rod end part of a spark rod.SOLUTION: A surface combustion burner 1 comprises an air pipe 3, a fuel pipe 4, a combustion header 2, a ventilation member 26, and a spark rod 5. A plurality of fuel injection outlets 221, 222 for injecting a fuel gas F, and a plurality of first air injection ports 23 for injecting combustion air A are formed at a nozzle part 21 of the combustion header 2. A discharge protrusion 210 is formed at a position opposing a discharge rod end part 511 of the spark rod 5 in a radial direction R at an outside face of a region of the nozzle part 21 at a base end side L2 in an axial direction L. The plurality of fuel injection ports 221, 222 are formed at a tip side L1 in the axial direction L rather than a forming position of the discharge protrusion 210.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a surface combustion burner. [Background technology]

[0002] There are various burners that form a flame by burning fuel gas and combustion air. Among them, a surface combustion burner that mixes and burns fuel gas and combustion air on the surface of a gas-permeable member is described in, for example, Patent Document 1. In this surface combustion burner, fuel gas that is ejected from the combustion header and flows from the inside to the outside of the gas-permeable member and combustion air that flows outside the combustion header are mixed and burned on the surface of the gas-permeable member to form a flame in the air pipe. In addition, it is difficult for the concentration of fuel gas ejected from the combustion header to be uneven. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-146028 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a surface combustion burner, a spark rod for igniting a mixture of fuel gas and combustion air is arranged facing the outside of a combustion header. However, in a conventional surface combustion burner, no special consideration has been given to the position of the discharge rod end of the spark rod, which generates a spark between the discharge rod end and a ground part provided in the combustion header. Therefore, there is a problem that the discharge rod end of the spark rod is heated to a high temperature by the flame when the mixture is burned. Therefore, further consideration is required to improve the durability of the discharge rod end.

[0005] The present invention has been made in view of the above problems, and aims to provide a surface combustion burner capable of improving the durability of the discharge rod end of the spark rod. [Means for solving the problem]

[0006] One aspect of the present invention is an air pipe through which combustion air passes; a fuel pipe disposed within the air pipe and through which a fuel gas passes; a combustion header connected to a tip end side of the fuel pipe and disposed within the air pipe, the combustion header having a nozzle portion and a flange portion provided on a base end side of the nozzle portion in the axial direction; an air-permeable member provided on an outer surface of the nozzle portion and formed of a knitted fabric or a porous material; a spark rod disposed through the flange portion and having a discharge rod end disposed at a position facing an outer surface of the nozzle portion; the nozzle portion is formed with a plurality of fuel outlets for ejecting the fuel gas and a plurality of first air outlets for ejecting the combustion air, and the flange portion is formed with a plurality of second air outlets for ejecting the combustion air, a discharge protrusion is formed on an outer surface of the nozzle portion at a base end side in the axial direction at a position facing the discharge rod end, The fuel ejection ports are located in a surface combustion burner and are formed on the axial tip side of the position where the discharge protrusion is formed. Effect of the Invention

[0007] In the surface combustion burner of the above embodiment, the position of the discharge rod end of the spark rod and the position of the discharge protrusion of the nozzle part are devised. Specifically, the discharge protrusion is formed at a position facing the discharge rod end on the outer surface of the nozzle part at the base end side in the axial direction. Also, the discharge rod end is disposed at a position facing the outer surface of the nozzle part at the base end side in the axial direction. Furthermore, the multiple fuel ejection holes are formed on the tip side in the axial direction of the position of the discharge protrusion.

[0008] With these configurations, when combustion is carried out on a mixture of fuel gas ejected from the multiple fuel outlets of the nozzle section and combustion air ejected from the multiple first air outlets of the nozzle section and the multiple second air outlets of the flange section, it is possible to make it difficult for the flame caused by combustion near the surface of the breathable member to come into contact with the end of the discharge rod.

[0009] Therefore, according to the surface combustion burner of the above aspect, it is possible to improve the durability of the discharge rod end of the spark rod. [Brief description of the drawings]

[0010] [Figure 1] FIG. 4 is a cross-sectional view taken along line II in FIG. 3, showing the surface combustion burner according to the embodiment. [Diagram 2] FIG. 4 is a cross-sectional view taken along line II-II in FIG. 3, showing the surface combustion burner according to the embodiment. [Diagram 3] FIG. 3 is a view showing the surface combustion burner according to the embodiment, taken along the line III in FIG. 1 . [Figure 4] FIG. 2 is an enlarged cross-sectional view of a portion of FIG. 1 showing the surface combustion burner according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A preferred embodiment of the above-mentioned surface combustion burner will be described with reference to the drawings. <Embodiment> As shown in Figs. 1 to 3, the surface combustion burner 1 of this embodiment includes an air pipe 3, a fuel pipe 4, a combustion header 2, a gas-permeable member 26, and a spark rod 5. The air pipe 3 is configured to allow combustion air A to pass through. The fuel pipe 4 is disposed inside the air pipe 3, and configured to allow fuel gas F to pass through. The combustion header 2 is connected to the tip side L1 of the fuel pipe 4 in the axial direction L and disposed inside the air pipe 3, and has a nozzle portion 21 and a flange portion 24 provided on the base end side L2 of the nozzle portion 21 in the axial direction L. Note that the gas-permeable member 26 is omitted in Fig. 3.

[0012] The nozzle portion 21 is formed with a plurality of fuel outlets 221, 222 for ejecting the fuel gas F, and a plurality of first air outlets 23 for ejecting the combustion air A. The flange portion 24 is formed with a plurality of second air outlets 241 for ejecting the combustion air A.

[0013] The breathable member 26 is provided on the outer surface of the nozzle portion 21 and is formed of a metal knit. The spark rod 5 is disposed penetrating the flange portion 24 in the axial direction L and has a discharge rod end 511 at a position facing the outer surface of the nozzle portion 21. A discharge protrusion 210 is formed on the outer surface of the nozzle portion 21 at a position facing the discharge rod end 511 in the radial direction R at a portion of the base end side L2 in the axial direction L. The multiple fuel ejection holes 221, 222 are formed on the tip side L1 in the axial direction L from the position where the discharge protrusion 210 is formed.

[0014] In this embodiment, the axial direction L refers to a direction parallel to the central axis of the air pipe 3 and the fuel pipe 4. In the axial direction L, the downstream side of the flow of combustion air A in the air pipe 3 and the downstream side of the flow of fuel gas F in the fuel pipe 4 are referred to as the tip side L1, and the opposite side of the tip side L1 is referred to as the base side L2. The circumferential direction C refers to a direction around the central axis of the air pipe 3 and the fuel pipe 4. The radial direction R refers to a radial direction perpendicular to the axial direction L and centered on the central axis of the air pipe 3 and the fuel pipe 4.

[0015] The surface combustion burner 1 of this embodiment will be described in detail below. The surface combustion burner 1 of this embodiment is attached to a heating furnace or the like and is used to heat the atmospheric gas in the furnace. As shown in Figs. 1 and 2, the air pipe 3 and the fuel pipe 4 are arranged parallel to each other, and have a double pipe structure. The tip of the air pipe 3 in the axial direction L is located on the tip side L1 in the axial direction L further than the tip of the combustion header 2 in the axial direction L. The entire outer periphery of the combustion header 2 is covered by the air pipe 3. When the combustion header 2 is arranged in the air pipe 3, a small gap is formed between the flange portion 24 of the combustion header 2 and the air pipe 3. In the structure of the surface combustion burner 1 that is actually used, the air pipe 3 may be arranged on the inner periphery side of the exhaust pipe through which the exhaust gas after combustion flows.

[0016] (Combustion header 2) 1, the nozzle section 21 of the combustion header 2 has a parallel section 212 parallel to the axial direction L, and an inclined section 211 located on the tip side L1 in the axial direction L of the parallel section 212. The inclined section 211 has a dimension in the radial direction R that decreases toward the tip side L1 in the axial direction L, and the breathable member 26 is disposed opposite the outer surface of the inclined section 211. The outer surface of the inclined section 211 of the nozzle section 21 is formed as a tapered outer surface 201 whose outer shape (dimension in the radial direction R) decreases toward the tip side L1 in the axial direction L.

[0017] 2 and 3, the nozzle portion 21 has a protrusion 22 in which a plurality of first fuel ejection ports 221 are formed, and a plurality of recesses 230 forming the first air ejection ports 23, which are alternately formed in the circumferential direction C. Each recess 230 is formed recessed inward in the radial direction R from the outer surface of the protrusion 22. The first fuel ejection ports 221 and the first air ejection ports 23 are alternately formed at a plurality of locations in the circumferential direction C of the combustion header 2.

[0018] The flange portion 24 has a disk shape, and is formed at an end portion on the base end side L2 in the axial direction L of the combustion header 2, protruding outward in the radial direction R beyond the nozzle portion 21. In addition to a plurality of second air ejection holes 241, the flange portion 24 is formed with an insertion hole 242 for inserting the spark rod 5. One of the second air ejection holes 241 functions as a flame monitoring hole 243 in which a flame detector for monitoring the flame formation state is disposed.

[0019] 1 and 2, a fuel passage 20 to which fuel gas F is supplied from the fuel pipe 4 is formed in the center, including the central axis, of the nozzle portion 21 and the flange portion 24. A portion on the tip side L1 in the axial direction L of the fuel passage 20 is closed. The central axis of the combustion header 2 is parallel to the central axes of the air pipe 3 and the fuel pipe 4. The fuel passage 20 is formed in the center, including the central axis of the combustion header 2.

[0020] 1 and 3, the multiple first fuel ejection holes 221 are formed in the multiple protrusions 22 so as to branch outward in the radial direction R from the fuel passage 20. The multiple first fuel ejection holes 221 are formed at multiple locations around the central axis of the combustion header 2 in a state in which the fuel passage 20 communicates with the tapered outer side surface 201. The multiple first fuel ejection holes 221 are formed along the radial direction R.

[0021] 2, portions of the first air outlets 23 on the base end side L2 in the axial direction L are formed as through holes 231, and portions of the first air outlets 23 on the tip end side L1 in the axial direction L are formed as recesses 230 connected to the through holes 231. The second air outlets 241 are aligned in the circumferential direction C of the flange portion 24, and are formed so as to penetrate the flange portion 24 in the axial direction L.

[0022] 1, the multiple fuel ejection ports 221, 222 in this embodiment are composed of multiple first fuel ejection ports 221 and second fuel ejection ports 222 located on the base end side L2 in the axial direction L of the multiple first fuel ejection ports 221. The multiple first fuel ejection ports 221 are formed at multiple locations in the axial direction L and circumferential direction C in the inclined portion 211 of the nozzle portion 21. The second fuel ejection port 222 is formed in a position in the parallel portion 212 of the nozzle portion 21 that is closer to the base end side L2 in the axial direction L than the positions where the multiple first fuel ejection ports 221 are formed and closer to the tip end side L1 in the axial direction L than the position where the discharge protrusion 210 is formed.

[0023] 4, the second fuel ejection port 222 is formed at a position overlapping with the arrangement position of the discharge rod end 511 in the circumferential direction C of the parallel portion 212 of the nozzle portion 21. In other words, the second fuel ejection port 222 is formed at a position facing the discharge rod end 511 in the radial direction R, or at a position on the tip side L1 in the axial direction L of the position facing the discharge rod end 511 in the radial direction R. The fuel gas F ejected from the second fuel ejection port 222 is ejected around the portion where a spark is generated by the discharge rod end 511 and the discharge protrusion 210. This can improve the ignition ability of the mixture by the spark generated between the discharge rod end 511 and the discharge protrusion 210.

[0024] 3, the position of second fuel ejection port 222 that overlaps with the arrangement position of discharge rod end 511 in circumferential direction C of parallel portion 212 of nozzle portion 21 may be, for example, a position within 5° on both sides of the center position in circumferential direction C of discharge rod end 511. In this embodiment, only one second fuel ejection port 222 is formed. The second fuel ejection ports 222 may be formed distributed on both sides of circumferential direction C centered on the position of discharge rod end 511 in circumferential direction C.

[0025] 1 and 2, the combustion header 2 of this embodiment is formed by joining a first header part 2A in which a fuel passage 20, a nozzle portion 21, a plurality of first fuel nozzles 221, a portion of the second fuel nozzles 222, and a plurality of first air nozzles 23 are formed, and a second header part 2B in which a discharge protrusion 210, the remaining portion of the second fuel nozzle 222, a flange portion 24, and a plurality of second air nozzles 241 are formed. The second header part 2B is attached to the outer periphery of a portion of the base end side L2 in the axial direction L of the first header part 2A.

[0026] (Breathable material 26) 1 and 2, the breathable member 26 of this embodiment is made of a metal knit formed by weaving a heat-resistant metal fiber material as a fiber material. The breathable member 26 is disposed facing the tapered outer surface 201 of the convex portion 22 of the inclined portion 211 in the nozzle portion 21 of the combustion header 2. An end portion on the base end side L2 in the axial direction L of the breathable member 26 is joined by welding or the like to a position on the tip side L1 in the axial direction L of the parallel portion 212 of the nozzle portion 21.

[0027] The breathable member 26 may be made of metal or ceramics having a plurality of pores or gaps that allow gas to pass therethrough, in addition to metal knit. The breathable member 26 may be made of glass wool made of glass fiber material, for example. The breathable member 26 may also be made of various materials that are heat resistant, breathable, and non-flammable.

[0028] (Spark Rod 5) 1 and 4, the spark rod 5 is composed of a central conductor 51 made of a conductive metal material and an insulator 52 made of an insulating ceramic material covering the outer periphery of the central conductor 51. The insulator 52 is not provided at the end of the central conductor 51 on the tip side L1 in the axial direction L. The end of the central conductor 51 on the tip side L1 in the axial direction L is exposed to the outside as a discharge rod end 511. The central axis of the spark rod 5 is parallel to the central axes of the air tube 3 and the fuel tube 4.

[0029] (Relationship between discharge rod end 511 and discharge protrusion 210) As shown in Figs. 1 to 4, the discharge protrusion 210 is formed on the outer surface of the parallel portion 212 of the nozzle portion 21 of the combustion header 2, protruding outward in the radial direction R beyond the general portion of the parallel portion 212. The discharge protrusion 210 is formed in a band shape whose length in the circumferential direction C is longer than its length in the axial direction L. With this configuration, even if the portion of the discharge protrusion 210 facing the discharge rod end 511 is worn away by discharge, a discharge can be generated between the discharge rod end 511 and portions of the discharge protrusion 210 on both sides of the worn portion in the circumferential direction C. Therefore, the discharge performance can be maintained for a long period of time.

[0030] 4, the width c of the discharge protrusion 210 in the axial direction L is 3 to 5 mm. With this configuration, a discharge can be appropriately generated between the discharge rod end 511 and the discharge protrusion 210. The length of the discharge protrusion 210 in the circumferential direction C is greater than the width of the discharge protrusion 210 in the axial direction L and may be 5 mm or more.

[0031] 3, the discharge protrusion 210 of this embodiment is formed continuously around the entire circumference in the circumferential direction C in the parallel portion 212 of the nozzle portion 21. This configuration makes it easy to form the discharge protrusion 210 in the parallel portion 212 of the nozzle portion 21. The outer surface in the radial direction R of the discharge protrusion 210 of this embodiment is formed along the circumferential direction C parallel to the axial direction L. The shape of the outer surface in the radial direction R of the discharge protrusion 210 in the axial direction L may be a convex curved surface.

[0032] 4, in this embodiment, the distance b from the end face 245 of the tip side L1 in the axial direction L of the flange portion 24 to the end face 213 of the base end side L2 in the axial direction L of the discharge protrusion 210 is set within a range of 6 to 12 mm. Also, the distance a from the end face 245 of the tip side L1 in the axial direction L of the flange portion 24 to the end position 521 of the base end side L2 in the axial direction L of the discharge rod end portion 511 (the end position 521 of the tip side L1 in the axial direction L of the insulator portion 52) is set within a range of b-1 mm to b+2 mm with respect to the distance b.

[0033] In other words, the end position of the base end side L2 in the axial direction L of the discharge rod end 511 is set within a range of 1 mm on the base end side L2 in the axial direction L and within 2 mm on the tip side L1 in the axial direction L with respect to the axial position of the end face 213. With this configuration, a discharge can be appropriately generated between the discharge rod end 511 and the discharge protrusion 210.

[0034] If the end position 521 on the base end side L2 in the axial direction L of the discharge rod end 511 is separated from the position of the end face 213 on the base end side L2 in the axial direction L of the discharge protrusion 210 by more than 1 mm on the base end side L2 in the axial direction L, the following problem may occur: Discharge may occur not only between the discharge rod end 511 and the discharge protrusion 210, but also between the discharge rod end 511 and a general part of the parallel part 212 which is located on the base end side L2 in the axial direction L relative to the discharge protrusion 210, causing an ignition delay.

[0035] 4, second fuel ejection port 222 is formed in a general portion of parallel portion 212 of nozzle portion 21, at a position on tip side L1 in the axial direction L from the position where discharge convex portion 210 is formed. In this embodiment, second fuel ejection port 222 is formed at a position between the end position of base end side L2 in the axial direction L of breathable member 26 and the end face of tip side L1 in the axial direction L of discharge convex portion 210.

[0036] (Combustion in surface combustion burner 1) In the surface combustion burner 1, the combustion header 2 guides the fuel gas F and the combustion air A through separate paths up to just before the breathable member 26, and the fuel gas F and the combustion air A are mixed and burned on the surface of the breathable member 26. When combustion is performed in the surface combustion burner 1, the fuel gas F passes through the fuel pipe 4 and the fuel passage 20 of the combustion header 2, branches from the fuel passage 20 to a plurality of first fuel ejection ports 221 and second fuel ejection ports 222, and is ejected from the open tips of the fuel ejection ports 221, 222 of the nozzle portion 21, passing through the breathable member 26 from the inside to the outside in the radial direction R.

[0037] On the other hand, the combustion air A passes through the air pipe 3, and branches off to flow through the multiple first air outlets 23 of the nozzle portion 21 of the combustion header 2 and the multiple second air outlets 241 of the flange portion 24 of the combustion header 2. The combustion air A is ejected from the opening tips of the multiple first air outlets 23 of the nozzle portion 21, passes through the breathable member 26 from the inside to the outside in the radial direction R, and is ejected from the multiple second air outlets 241 of the flange portion 24, and passes to the tip side L1 in the axial direction L of the combustion header 2.

[0038] The fuel gas F ejected from the multiple first fuel nozzles 221 and the combustion air A ejected from the multiple first air nozzles 23 move in the circumferential direction C and mix with each other near the surface of the breathable member 26. Also, near the surface of the breathable member 26, the fuel gas F ejected from the multiple first fuel nozzles 221 and the combustion air A ejected from the multiple first air nozzles 23 are mixed with the combustion air A ejected from the multiple second air nozzles 241. This allows the fuel gas F and the combustion air A to be sufficiently mixed near the surface of the breathable member 26, making it possible to prevent the concentration of the fuel gas F in the mixture from becoming uneven.

[0039] Furthermore, the mixture of fuel gas F and combustion air A is ignited by a spark generated between the discharge rod end 511 of the spark rod 5 and the discharge protrusion 210 of the nozzle portion 21, and burns near the surface of the breathable member 26, forming a flame in the air pipe 3. At this time, since the concentration of the fuel gas F in the mixture is unlikely to be biased, a stable flame can be formed.

[0040] (Action and effect) In the surface combustion burner 1 of this embodiment, the positions at which the discharge rod end 511 of the spark rod 5 and the discharge protrusion 210 of the nozzle portion 21 are formed are devised. Specifically, the discharge protrusion 210 is formed at a position facing the discharge rod end 511 in the radial direction R on the outer surface of the parallel portion 212 of the nozzle portion 21. The discharge rod end 511 is also disposed at a position facing the discharge protrusion 210 in the radial direction R. Furthermore, the multiple first fuel ejection holes 221 and second fuel ejection holes 222 are formed on the tip side L1 in the axial direction L relative to the position at which the discharge protrusion 210 is formed.

[0041] With these configurations, when a mixture of the fuel gas F ejected from the multiple first fuel nozzles 221 of the nozzle portion 21 and the combustion air A ejected from the multiple first air nozzles 23 of the nozzle portion 21 and the multiple second air nozzles 241 of the flange portion 24 is combusted, it is possible to make it difficult for a flame caused by combustion near the surface of the breathable member 26 to come into contact with the discharge rod end portion 511. As a result, the spark rod 5 is difficult to heat up, and deformation of the spark rod 5 due to overheating at the time of ignition can be suppressed.

[0042] Furthermore, in this embodiment, by forming the second fuel nozzle 222, even in a configuration in which the discharge rod end 511 is shifted toward the base end side L2 in the axial direction L from the position where the flame is formed, poor ignition by the spark rod 5 is prevented. Furthermore, by configuring the discharge protrusion 210 in a band shape that is long in the circumferential direction C, the ignition performance of the spark rod 5 is maintained for a long period of time.

[0043] Therefore, according to the surface combustion burner 1 of this embodiment, the durability of the discharge rod end 511 of the spark rod 5 can be improved.

[0044] The present invention is not limited to the embodiments, and further different embodiments can be configured without departing from the spirit of the present invention. In addition, the present invention includes various modifications, modifications within the scope of the equivalents, and the like. [Explanation of symbols]

[0045] 1 Surface Combustion Burner 2 Combustion header 21 Nozzle section 210 Discharge protrusion 211 Inclined area 212 Parallel Section 221 1st fuel injection port 222 2nd fuel injection port 23 First air outlet 24 Flange 241 Second air outlet 26 Breathable materials 3 Air Pipe 4 fuel pipe 5 Spark Rod 511 Discharge rod end

Claims

1. an air pipe through which combustion air passes; a fuel pipe disposed within the air pipe and through which a fuel gas passes; a combustion header connected to a tip end side of the fuel pipe in an axial direction along a central axis thereof and disposed within the air pipe, the combustion header having a nozzle portion and a flange portion provided on a base end side of the nozzle portion in the axial direction; a breathable member provided on an outer surface of the nozzle portion and made of a fiber material or a porous material; a spark rod disposed through the flange portion and having a discharge rod end disposed at a position facing an outer surface of the nozzle portion; the nozzle portion is formed with a plurality of fuel outlets for ejecting the fuel gas and a plurality of first air outlets for ejecting the combustion air, and the flange portion is formed with a plurality of second air outlets for ejecting the combustion air, a discharge protrusion is formed on an outer surface of the nozzle portion at a base end side in the axial direction at a position facing the discharge rod end, A surface combustion burner, wherein the fuel ejection ports are formed on a tip side in the axial direction relative to a position where the discharge protrusion is formed.

2. 2. The surface combustion burner according to claim 1, wherein said discharge protrusion is formed in a band shape whose circumferential length around the central axis of said fuel tube is longer than its axial length.

3. 3. The surface combustion burner according to claim 1, wherein the plurality of fuel ejection ports are composed of a plurality of first fuel ejection ports formed at a plurality of locations in the axial direction of the nozzle portion and in a circumferential direction around a central axis of the fuel tube, and a second fuel ejection port formed at a position that is closer to the base end in the axial direction than the positions at which the plurality of first fuel ejection ports are formed and closer to the tip end in the axial direction than the position at which the discharge protrusion is formed, and that overlaps in the circumferential direction with a position at which the discharge rod end is arranged.

4. the nozzle portion has a parallel portion parallel to the axial direction, and an inclined portion located on a tip side of the parallel portion in the axial direction, the inclined portion having a radial dimension about a central axis of the fuel pipe decreasing toward the tip side in the axial direction, and the inclined portion in which the air-permeable member is disposed, 4. The surface combustion burner according to claim 1, wherein the discharge protrusion is formed continuously over the entire circumferential direction around the central axis of the fuel pipe in the parallel portion.

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