Combustion equipment

Abstract

To prevent insufficient cooling of a heat block plate in a combustion apparatus in which a burner positioning frame 7 having a rear frame part 71 positioned on a rear side of a burner arrangement part and a side frame part 72 positioned on an outside in a lateral direction of the burner arrangement part is arranged in a combustion chamber in a combustion case; a longitudinal throttle part 713 is formed in a lateral direction recessed backward in the rear frame part 71; secondary air from a distribution hole positioned at a part close to the rear end of a partition plate on the underside of the combustion chamber is prevented from flowing upward from between the partition plate and a lower edge 711 of the rear frame part 71 through a gap between the rear frame part 71 and a rear plate part of the combustion case by the throttle part 713; and the secondary air flows upward along the front face of the rear frame part 71 so that the heat block plate covering the upper inner surface of the rear plate part of the combustion case is cooled by the secondary air.SOLUTION: There is provided a suppression part 723 for suppressing inflow of secondary air flowing into a gap between a rear frame part 71 and a rear plate part of a combustion casing into a gap between each side frame part 72 and a side plate unit of each side in a lateral direction of the combustion case at a position below a throttle part 713.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a combustion device which comprises a combustion housing, within which a partition plate is provided that divides the space within the combustion housing into a combustion chamber and an air supply chamber below the combustion chamber, and in which a plurality of burners longitudinal in the front-to-rear direction are arranged side by side in the combustion chamber, each burner having an inlet at its lower front end through which fuel gas and primary air flow in and a flame port at its upper end through which a mixture of fuel gas and primary air is ejected, and in which secondary air is supplied from the air supply chamber to the combustion chamber through a number of distribution holes formed in the partition plate. [Background technology]

[0002] Conventionally, as this type of combustion device, there is known a burner positioning frame arranged in a combustion chamber, the frame rear part being located on the rear side of the burner arrangement part, and a pair of side frame parts being located on both lateral outer sides of the burner arrangement part (see, for example, Patent Document 1). In this type, the lower edge of the rear frame part is positioned above the partition plate. The lower edge of the rear frame part is bent forward and engaged with a recessed part formed in the rear edge part of each burner, so that the burners do not float up.

[0003] In addition, in this combustion casing, a laterally long constricted portion is formed in the rear frame portion and protrudes rearward toward the rear plate portion of the combustion casing. Therefore, the constricted portion can prevent the secondary air flowing in from the distribution holes located in the portion near the rear end of the partition plate from flowing upward through the gap between the partition plate and the lower edge of the rear frame portion and the rear plate portion of the combustion casing. As a result, the secondary air flowing in from the distribution holes located in the portion near the rear end of the partition plate flows upward along the front surface of the rear frame portion, and the heat shield covering the upper inner surface of the rear plate portion of the combustion casing is cooled by this secondary air.

[0004] However, the secondary air that flows into the gap between the rear frame and the rear plate of the combustion housing from between the partition plate and the lower edge of the rear frame may flow forward through the gaps between each side frame and each side plate of the combustion housing in the lateral direction below the constriction, resulting in a decrease in the amount of secondary air flowing upward along the front surface of the rear frame, which may result in insufficient cooling of the heat shield. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-125685 A Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above, an object of the present invention is to provide a combustion apparatus capable of preventing insufficient cooling of a heat shield covering an upper inner surface of a rear plate portion of a combustion box. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a combustion device that includes a combustion housing, in which a partition plate is provided that divides the space within the combustion housing into a combustion chamber and an air supply chamber below the combustion chamber, and a plurality of burners that are longitudinal in the front-to-rear direction are arranged side by side in the combustion chamber, each burner having an inlet at its lower front end through which fuel gas and primary air flow in and a flame port at its upper end through which a mixture of fuel gas and primary air ejects, and secondary air is supplied to the combustion chamber from the air supply chamber through a number of distribution holes formed in the partition plate, and a burner positioning frame is arranged in the combustion chamber, the burner positioning frame having a rear frame portion located on the rear side of the burner arrangement portion and a pair of side frame portions located on both lateral sides of the burner arrangement portion, the lower edge of the rear frame portion is located above the partition plate, and the rear frame portion is attached to the rear plate portion of the combustion housing. a restrictor portion is formed which is longitudinally long and recessed rearward toward the rear end of the partition plate, and the restrictor portion restricts the secondary air flowing in from the distribution holes located in the portion near the rear end of the partition plate from flowing upward through the gap between the partition plate and the lower edge of the rear frame portion and the rear plate portion of the combustion casing, so that the secondary air flowing in from the distribution holes located in the portion near the rear end of the partition plate flows upward along the front surface of the rear frame portion and the heat shield covering the upper inner surface of the rear plate portion of the combustion casing is cooled by this secondary air, and is characterized in that a restrictor portion is provided below the restrictor portion which restricts the secondary air that has flowed in from between the partition plate and the lower edge of the rear frame portion into the gap between the rear frame portion and the rear plate portion of the combustion casing from flowing into the gap between each side frame portion and each side plate portion on the lateral side of the combustion casing.

[0008] According to the present invention, it is possible to prevent secondary air flowing in from the distribution holes located in the portion near the rear end of the partition plate from flowing from between the partition plate and the lower edge of the rear frame portion through the gap between the rear frame portion and the rear plate portion of the combustion housing into the gaps between each side frame portion and each side plate portion of the combustion housing. Therefore, it is possible to ensure a sufficient amount of secondary air flowing upward along the front surface of the rear frame portion, and to prevent insufficient cooling of the heat shield plate facing the upper inner surface of the rear plate portion of the combustion housing.

[0009] In the present invention, it is preferable to form a cut-and-raised piece that is cut out and raised outward in the lateral direction in the portion near the rear end of each side frame, and to use this cut-and-raised piece to constitute the suppressing portion, or to form a second drawn portion that extends downward from each lateral end of the drawn portion and is recessed backward in the rear frame, and to use this second drawn portion to constitute the suppressing portion. This allows the suppressing portion to be provided without increasing the number of parts, which is advantageous in terms of reducing costs. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view of a combustion device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a plan view of the combustion device according to the embodiment. [Diagram 3] FIG. 3 is a cross-sectional side view taken along line III-III in FIG. 2. [Figure 4] 2 is a cross-sectional view of a flame port of a burner provided in the combustion device of the embodiment. FIG. [Diagram 5] FIG. 2 is a perspective view of a burner positioning frame provided in the combustion device of the embodiment, as viewed obliquely from the front. [Figure 6] FIG. 13 is a perspective view of a modified example of the burner positioning frame, as viewed obliquely from the rear. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 1 to 3, the combustion device according to the embodiment of the present invention includes a combustion housing 1. The combustion housing 1 has a front plate 11 at the front upper portion, side plate portions 12, 12 on both lateral sides, a rear plate 13, and a bottom plate 14, and further has a connection flange portion 15 at the upper end for connecting a heat exchanger (not shown) for hot water supply or the like. A partition plate 2 is provided inside the combustion housing 1 to separate the space inside the combustion housing 1 into a combustion chamber 1a and an air supply chamber 1b below the combustion chamber 1a. A fan (not shown) is connected to the bottom surface of the air supply chamber 1b, i.e., the bottom plate portion 14. Air from the fan is supplied as secondary air from the air supply chamber 1b to the combustion chamber 1a through a number of distribution holes 21 formed in the partition plate 2.

[0012] In the combustion chamber 1a, a plurality of burners 3, each elongated in the front-rear direction, are arranged in the horizontal direction. Each burner 3 has an inlet 31 at the lower front end through which fuel gas and primary air flow in, and a flame port 32 at the upper end from which a mixture of fuel gas and primary air is ejected. As shown in FIG. 4, the flame port 32 is composed of a lean flame port 321 that ejects a lean mixture having a fuel concentration less than the theoretical air-fuel ratio, and a pair of rich flame ports 322, 322 located on both lateral sides of the lean flame port 321 and ejecting a rich mixture having a fuel concentration richer than the lean mixture. In addition, a plurality of straightening plates 323 are installed in the horizontal direction at intervals in the lean flame port 321, and further, a reflux area 324 from which the mixture is not ejected is provided on both sides of the lean flame port 321. As shown in FIG. 2, at the lower front end of the burner 3, there are provided inlets 31, which include a first inlet 311 connected to a light flame port 321 and a second inlet 312 located above the first inlet 311 and connected to a rich flame port 322.

[0013] The front end of the partition plate 2 is provided with an upwardly extending upright plate portion 22 and an upper plate portion 23 that is bent forward from the upper end of the upright plate portion 22 to reach the front plate portion 11 of the combustion housing 1. In this embodiment, the front end of the upper plate portion 23 is bent upward to integrally form the front plate portion 11. The upright plate portion 22 is provided with openings 221, 222 that match the first and second inlets 311, 312 of each burner 3, and further, a manifold 4 is attached in front of the upright plate portion 22 so as to close the lower front surface of the combustion housing 1. The manifold 4 is provided with first and second gas nozzles 41, 42 that face the first and second inlets 311, 312 of each burner 3. Fuel gas is supplied from the first and second gas nozzles 41, 42 to the first and second inlets 311, 312, and primary air is supplied from the air supply chamber 1b to the inlets 311, 312 through a gap defined between the standing plate portion 22 and the manifold 4. Note that the manifold 4 is omitted in FIG. 1.

[0014] An electrode part 5 having an ignition electrode 51 and a flame rod 52, and further provided with an observation window 53, is attached to the front plate part 11 of the combustion housing 1. In addition, a burner positioning plate 6 is provided on the inner surface of the front plate part 11. At the upper end of the burner positioning plate 6, a plurality of bent claw pieces 61 to be inserted into the gaps between the front ends of the burners 3 are formed.

[0015] A burner positioning frame 7 is also arranged in the combustion chamber 1a. Referring also to Fig. 5, the burner positioning frame 7 has a rear frame portion 71 located on the rear side of the burner arrangement portion, and a pair of side frame portions 72, 72 located on both lateral outer sides of the burner arrangement portion. The burner positioning frame 7 is fixed to the front plate portion 11 of the combustion housing 1 by screws 73 at flange portions 721 curved at the front ends of the side frame portions 72, and is fixed to the partition plate 2 by screws 74 at tongue portions 722 extending from the rear parts of the lower edges of the side frame portions 72.

[0016] The lower edge 711 of the rear frame portion 71 is located above the partition plate 2. The lower edge 711 is bent forward to engage with the recessed portion 33 formed in the rear edge of each burner 3, thereby preventing each burner 3 from floating up. In addition, a plurality of claw pieces 712 to be inserted into the gaps between the rear ends of each burner 3 are bent at the upper end of the rear frame portion 71, and slits 711a are formed at the lower edge 711 of the rear frame portion 71 to engage with the forward recessed portion of the recessed portion 33 at the rear edge of each burner 3, thereby positioning each burner 3.

[0017] Further, a vent hole 711b is formed between the slits 711a, 711a on the lower edge 711 of the rear frame portion 71. Secondary air flowing in from the distribution holes 21 located in the portion near the rear end of the partition plate 2 flows upward along the front surface of the rear frame portion 71 through the vent hole 711b as shown by the arrow in Fig. 3, and this secondary air rises along the front surface of the heat shield plate 131 covering the upper inner surface of the rear plate portion 13 of the combustion housing 1 through the gaps between the claw pieces 712, 712. Therefore, the heat shield plate 131 is cooled by this secondary air.

[0018] Here, since the lower edge 711 of the rear frame portion 71 is located above the partition plate 2, there is a possibility that the secondary air flowing in from the distribution holes 21 located in the portion near the rear end of the partition plate 2 will flow into the gap between the rear frame portion 71 and the rear plate portion 13 of the combustion housing 1 from between the partition plate 2 and the lower edge 711 of the rear frame portion 71. If this secondary air flows upward through the gap between the rear frame portion 71 and the rear plate portion 13 of the combustion housing 1, the amount of secondary air flowing upward along the front surface of the rear frame portion 71 will decrease, and the heat shield plate 131 will not be able to be sufficiently cooled. For this reason, the rear frame portion 71 is formed with a laterally long narrowed portion 713 that is recessed rearward toward the rear plate portion 13 of the combustion housing 1. The narrowed portion 713 can prevent the secondary air flowing in from the distribution holes 21 located in the portion near the rear end of the partition plate 2 from flowing upward through the gap between the rear frame portion 71 and the rear plate portion 13 of the combustion housing 1 from between the partition plate 2 and the lower edge 711 of the rear frame portion 71.

[0019] However, simply forming the throttle portion 713 causes the following problem. That is, the secondary air that flows from between the partition plate 2 and the lower edge 711 of the rear frame portion 71 into the gap between the rear frame portion 71 and the rear plate portion 13 of the combustion housing 1 may flow forward through the gap between each side frame portion 72 of the burner positioning frame 7 and each side plate portion 12 on the lateral side of the combustion housing 1 at a position below the throttle portion 713. As a result, the amount of secondary air that flows upward along the front surface of the rear frame portion 71 decreases, which may result in insufficient cooling of the heat shield plate 131.

[0020] Therefore, in this embodiment, a suppression section is provided below the throttle section 713 to suppress the secondary air that has flowed into the gap between the rear frame section 71 and the rear plate section 13 of the combustion housing 1 from flowing into the gap between each side frame section 72 and each side plate section 12 in the lateral direction of the combustion housing 1 from between the partition plate 2 and the lower edge 711 of the rear frame section 71. Specifically, cut-and-raised pieces 723 cut and raised outward in the lateral direction are formed in a portion near the rear end of each side frame section 72, and these cut-and-raised pieces 723 constitute the suppression section.

[0021] According to this, the cut-and-raised pieces 723 can prevent the secondary air flowing in from the distribution holes 21 located in the portion near the rear end of the partition plate 2 from flowing from between the partition plate 2 and the lower edge 711 of the rear frame portion 71 through the gap between the rear frame portion 71 and the rear plate portion 13 of the combustion housing 1 into the gap between each side frame portion 72 and each side plate portion 12 of the combustion housing 1. Therefore, a sufficient amount of secondary air can be secured to flow upward along the front surface of the rear frame portion 71, and insufficient cooling of the heat shield plate 131 can be prevented.

[0022] Next, a modified example of the burner positioning frame 7 will be described with reference to Fig. 6. The basic structure of the burner positioning frame 7 of this modified example is not particularly different from that of the burner positioning frame 7 of the above embodiment, and the same members and parts as those of the above embodiment are given the same reference numerals. The difference between the burner positioning frame 7 of the modified example and that of the above embodiment is that instead of forming cut and raised pieces 723 on each side frame portion 72, second narrowed portions 714 that are recessed backward and extend downward from each lateral end of the narrowed portion 713 are formed on the rear frame portion 71, and these second narrowed portions 714 form the suppression portion.

[0023] According to this, the secondary air that flows into the gap between the rear frame portion 71 and the rear plate portion 13 of the combustion housing 1 is confined between the second constricted portions 714, 714 on both lateral sides at a position below the constricted portion 713. Therefore, the second constricted portions 714 can prevent the secondary air that flows into the gap between the rear frame portion 71 and the rear plate portion 13 of the combustion housing 1 from flowing into the gaps between each side frame portion 72 and each side plate portion 12 on each lateral side of the combustion housing 1 at a position below the constricted portion 713. In other words, the second constricted portions 714 form a suppression portion.

[0024] 5, the rear ends 724 of the lower halves of the side frame parts 72 are positioned slightly forward of the front-rear position of the rear frame part 71, but in the burner positioning frame 7 shown in Fig. 6, the front-rear position of the rear ends 724 of the lower halves of the side frame parts 72 is equal to the front-rear position of the rear frame part 71. This makes it possible to prevent secondary air flowing in from the distribution holes 21 located in the portion near the rear end of the partition plate 2 from flowing in between the side frame parts 72 and the side plate parts 12 on each side in the lateral direction of the combustion housing 1 at a position below the rear frame part 71.

[0025] Although the embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited thereto. For example, it is possible to attach a separate member serving as the suppression portion to the burner positioning frame 7. However, if the suppression portion is formed of the cut and raised piece 723 or the second narrowed portion 714 as in the above embodiment, the suppression portion can be provided without increasing the number of parts, which is advantageous in terms of reducing costs. In addition, in the above embodiment, the burner 3 is formed of a so-called light-light burner having a light flame port 321 and a light flame port 322, but the burner 3 may be formed of a normal Bunsen burner omitting the light flame port 322. [Explanation of symbols]

[0026] 1...combustion housing, 1a...combustion chamber, 1b...air supply chamber, 13...rear plate portion, 131...heat shield plate, 2...partition plate, 21...distribution hole, 3...burner, 31...inlet, 32...flame port, 7...burner positioning frame, 71...rear frame portion, 711...lower edge of rear frame portion, 713...throttling portion, 714...second throttle portion (suppression portion), 72...side frame portion, 723...cut-and-raised piece (suppression portion).

Claims

1. A combustion device comprising a combustion housing, in which a partition plate is provided that divides the space within the combustion housing into a combustion chamber and an air supply chamber below the combustion chamber, a plurality of burners longitudinal in the front-to-rear direction are arranged side by side in the combustion chamber, each burner having an inlet at its lower front end through which fuel gas and primary air flow in and a flame port at its upper end through which a mixture of fuel gas and primary air is ejected, and secondary air is supplied from the air supply chamber to the combustion chamber through a number of distribution holes formed in the partition plate, a burner positioning frame is disposed in a combustion chamber, the burner positioning frame having a rear frame portion located rearward of the burner arrangement portion and a pair of side frame portions located laterally outward of the burner arrangement portion, the lower edge of the rear frame portion is located above a partition plate, and a laterally long constricted portion is formed in this rear frame portion which is recessed rearward toward the rear plate portion of the combustion housing, and the constricted portion prevents secondary air flowing in from a distribution hole located in a portion near the rear end of the partition plate from flowing upward through a gap between the partition plate and the lower edge of the rear frame portion and between the rear frame portion and the rear plate portion of the combustion housing, so that the secondary air flowing in from the distribution hole located in the portion near the rear end of the partition plate flows upward along the front surface of the rear frame portion and a heat shield covering an upper inner surface of the rear plate portion of the combustion housing is cooled by this secondary air; A combustion device characterized in that a suppression section is provided that suppresses secondary air that has flowed into the gap between the rear frame section and the rear plate section of the combustion housing from between the partition plate and the lower edge of the rear frame section, from flowing into the gap between each side frame section and each side plate section on each lateral side of the combustion housing, at a position below the constriction section.

2. 2. The combustion apparatus according to claim 1, wherein a cut-and-raised piece is formed laterally outwardly at a portion near the rear end of each of the side frame portions, and the cut-and-raised piece constitutes the suppression portion.

3. 2. The combustion device according to claim 1, wherein the rear frame portion is formed with a second constriction portion extending downward from each lateral end of the constriction portion and recessed rearward, and the suppression portion is constituted by this second constriction portion.

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