Combustion device

Abstract

A combustion device is provided with: a lean-dense burner provided with a lean flame port that ejects lean mixture and a dense flame port that ejects dense mixture on both sides in the lateral direction, and a flame rod arranged so as to face the upper part of the prescribed two adjacent specific lean-dense burners, whereby the reliability of the air excess ratio detection of the lean mixture performed by the flame rod is improved. The flame rod has: a first vertical rod portion that extends from the end portion on one side in the front-rear direction of the lean flame port of the one specific lean-dense burner to the other side in the front-rear direction; and a lateral rod portion that extends from the end portion on the other side in the front-rear direction of the first vertical rod portion to the other specific lean-dense burner side in the lateral direction. The tip of the lateral rod portion is positioned at the upper part of the lean flame port of the other specific lean-dense burner. A blocking member that blocks the portion of the dense flame port of each specific lean-dense burner positioned at the lower part of the lateral rod portion is also provided.

Description

Technical Field

[0001] This invention relates to a combustion device configured such that, in a combustion chamber, a plurality of rich-lean burners, which are longer in the front-to-back direction and have a lean flame port and a pair of rich flame ports at their upper ends, are arranged side by side in a transverse direction. The lean flame ports spray a lean mixture with a fuel concentration lower than the stoichiometric air-fuel ratio, and the pair of rich flame ports are located on both sides of the lean flame ports and spray a rich mixture with a fuel concentration higher than the lean mixture. The rich-lean burners are divided into multiple burner groups, and the combustion capacity is switched to multiple levels by changing the combination of the burner groups being burned. Background Technology

[0002] Conventionally, as such a combustion device, it is well known that two specific rich-lean burners among a plurality of rich-lean burners arranged side by side in the combustion chamber are selected as: specific rich-lean burners that burn even if any combustion capacity is at least one of them, and a flame bar extending laterally is arranged above the end of one of the two specific rich-lean burners, and flame monitoring is performed using the flame bar (for example, see Patent Document 1).

[0003] In addition, recently, a flame bar has also been used to detect the excess air ratio of the mixture ejected from the burner. Here, since in a rich-lean burner, the main flame is formed by the combustion of the lean mixture ejected from the lean flame port, and the side flame that sustains the main flame is formed by the combustion of the rich mixture ejected from the rich flame port, the mixture whose excess air ratio should be detected is the lean mixture that forms the main flame. As in the previous example described above, when a flame bar extending laterally is positioned above the ends of two specific rich-lean burners, the flame bar traverses the upper part of both the lean and rich flame ports of the two specific rich-lean burners. As a result, the excess air ratio detected using this flame bar becomes the excess air ratio of the mixture containing both the lean and rich mixtures.

[0004] In this case, it is possible to consider blocking the portion of the rich flame nozzle located directly below the flame bar in each specific rich-lean burner. Accordingly, the flame in contact with the flame bar will only become the combustion flame of the lean mixture ejected from the lean flame nozzle of each specific rich-lean burner, thus enabling the detection of the excess air ratio of the lean mixture.

[0005] However, when a laterally extending flame bar is positioned above the ends of two specific rich / lean burners, the following undesirable situation arises. Specifically, near the ends of the rich / lean burners, heat dissipates to the surroundings, resulting in relatively low temperatures. Consequently, the emission velocity of the lean mixture exceeds the combustion velocity, making flame lift more likely. As a result, the flame bar does not come into contact with the combustion flame of the lean mixture ejected from the lean flame nozzles of each specific rich / lean burner, reducing the reliability of the excess air rate detection of the lean mixture using the flame bar.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2011-252671 Summary of the Invention

[0009] In view of the above-mentioned problems, the present invention aims to provide a combustion device that can improve the reliability of detecting excess air rate in a lean mixture using a flame rod.

[0010] To address the aforementioned issues, the combustion device of the present invention comprises the following configuration: a plurality of rich-lean burners, elongated in the longitudinal direction and equipped with a lean flame port and a pair of rich flame ports at their upper ends, are arranged side-by-side in a transverse direction within the combustion chamber. The lean flame ports eject a lean mixture with a fuel concentration leaner than the stoichiometric air-fuel ratio, while the pair of rich flame ports, located on either side of the lean flame ports, eject a rich mixture with a fuel concentration richer than the lean mixture. The rich-lean burners are grouped into multiple burner groups, and the combustion capacity is switched to multiple levels by changing the combination of the burner groups. A predetermined number of rich-lean burners that are transversely adjacent are selected such that at least one of them achieves any combustion capacity. A combustion device comprising a flame bar arranged facing above two specific enrichment / lean burners, characterized in that the flame bar has: a first longitudinal section extending from one end of the specific enrichment / lean burner toward the other in a longitudinal direction, directly above the light flame port of one of the specific enrichment / lean burners; and a transverse section extending laterally in a curved manner from the other end of the first longitudinal section toward the side of the other specific enrichment / lean burner, the end of the transverse section being located directly above the light flame port of the other specific enrichment / lean burner, the combustion device comprising: a sealing member for sealing the portion of the enrichment flame port of each specific enrichment / lean burner located directly below the transverse section of the flame bar.

[0011] According to the present invention, since the first longitudinal rod of the flame rod extends from one end in the front-rear direction toward the other end in the front-rear direction directly above the light flame port of a specific rich-lean burner, the other end of the first longitudinal rod in the front-rear direction is located at a position directly above the portion of the light flame port that is somewhat difficult to produce flame lift-off from the end in the front-rear direction of the specific rich-lean burner. Furthermore, the end of the crossbar of the flame rod is also located at a position directly above the portion of the light flame port that is somewhat difficult to produce flame lift-off from the end in the front-rear direction of the other specific rich-lean burner. Therefore, the other end of the first longitudinal rod in the front-rear direction and the end of the crossbar are highly likely to come into contact with the combustion flame of the lean mixture ejected from the light flame ports of each of the specific rich-lean burners, thereby improving the reliability of the excess air rate detection of the lean mixture performed by the flame rod.

[0012] Furthermore, in this invention, it is preferable that the flame rod has a second longitudinal rod portion that bends and extends from the end of the horizontal rod portion toward the other direction in a front-rear direction at the upper part of the lean flame port of the other specific rich-lean burner. Accordingly, the second longitudinal rod portion can come into contact with the combustion flame of the lean mixture ejected from the lean flame port of the other specific rich-lean burner over a larger area, thereby further improving the reliability of the detection of the excess air ratio of the lean mixture.

[0013] However, rich-lean burners typically have multiple bridging sections spanning the upper edges of a pair of outer plates, located laterally outside the rich flame openings on both sides. Therefore, in this invention, it is preferable that the crossbar portion of the flame bar is located directly above the bridging section closest to one end of the two specific rich-lean burners in the longitudinal direction, and this bridging section forms the aforementioned sealing component. Accordingly, a separate sealing component is unnecessary, reducing the number of components and thus lowering costs. Furthermore, the bridging section blocks both the lean and rich flame openings from above, preventing the ejection of the mixture at the bridging section. Consequently, the ejection velocity of the mixture slows down near the bridging section, making it difficult for the combustion flame, especially the lean mixture flame, to detach. As a result, the reliability of the excess air rate detection of the lean mixture by the flame bar can be further improved. Attached Figure Description

[0014] Figure 1 This is a top view of the combustion device according to the first embodiment of the present invention.

[0015] Figure 2 It is along Figure 1 The sectional side view obtained by cutting along line II-II.

[0016] Figure 3 It is along Figure 1 A cross-sectional view of the key part obtained by cutting along line III-III.

[0017] Figure 4 This is a top view of the combustion device according to the second embodiment of the present invention.

[0018] Figure 5 It is along Figure 4 A cross-sectional view of the key part obtained by cutting along line V-V.

[0019] Explanation of reference numerals in the attached figures

[0020] 2…combustion chamber; 6…rich-lean burner; 61…first specific rich-lean burner (one party's specific rich-lean burner); 62…second specific rich-lean burner (the other party's specific rich-lean burner); 61…lean flame port; 62…rich flame port; 64…outer plate; 64a…bridging part; 67…sealing component; 9…flame rod; 91…first longitudinal rod part; 92…crossbar part; 93…second longitudinal rod part. Detailed Implementation

[0021] Reference Figure 1 as well as Figure 2 1 represents the combustion chamber. The upper surface of the combustion chamber 1 is open, and a heat exchanger or other heated component (not shown) is mounted on top of the combustion chamber 1. Inside the combustion chamber 1, a partition plate 4 is provided, dividing the space inside the combustion chamber 1 into a combustion chamber 2 and an air supply chamber 3 below it. A combustion fan (not shown) is connected to the bottom surface of the air supply chamber 3 via a channel 5, and air is supplied to the air supply chamber 3 from the combustion fan. Multiple distribution holes 4a are formed in the partition plate 4 at positions corresponding to the arrangement spacing of the rich and lean burners 6, which will be described later. Furthermore, the air supplied to the air supply chamber 3 is supplied to the combustion chamber 2 as secondary air through these distribution holes 4a.

[0022] Inside the combustion chamber 2, multiple relatively long rich-lean burners 6 are arranged side-by-side in a transverse direction. For example... Figure 3 As shown, each rich / lean burner 6 has the following at its upper end: a lean flame port 61, which sprays a lean mixture with a fuel concentration even leaner than the stoichiometric air-fuel ratio; and a pair of rich flame ports 62, 62, located laterally on both sides of the lean flame port 61, which spray a rich mixture with a fuel concentration even richer than the lean mixture. Furthermore, while the fuel concentration of the rich mixture is generally set to be richer than the stoichiometric air-fuel ratio, it can also be set to be slightly leaner than the stoichiometric air-fuel ratio.

[0023] A flow straightening component 63 is installed within the light flame port 61. This flow straightening component 63 has multiple flow straightening plates 63a that divide the light flame port 61 into multiple regions laterally. Additionally, recirculation regions 61a, located between the light flame port 61 and the rich flame port 62, are provided on both sides of the light flame port 61 and do not eject the mixture. Each rich / lean burner 6 also has multiple bridging portions 64a spanning the upper edges of a pair of outer side plates 64, 64, located laterally outside the rich flame ports 62, 62 on both sides.

[0024] Reference Figure 2 Each of the rich and lean burners 6 has a lean mixture inlet 65 and a rich mixture inlet 66 located above it at its lower front end. Additionally, a raised section 41 is formed by bending the leading edge of the partition plate 4, and a manifold 7 is mounted on the front side of the raised section 41 to block the lower front surface of the combustion chamber 1. The raised section 41 has openings facing the inlets 65 and 66 of each rich and lean burner 6. Furthermore, an air conditioning plate 42 with openings corresponding to the inlets 65 and 66 of each rich and lean burner 6 is mounted on the front surface of the raised section 41. The manifold 7 has gas nozzles 71 and 72 for the lean and rich mixtures, respectively, opposite to the inlets 65 and 66 of each rich and lean burner 6. Fuel gas is supplied from the gas nozzles 71 and 72 of the manifold 7 to the inlets 65 and 66 of the rich-lean burner 6. Primary air is supplied from the air supply chamber 3 through the gap between the stand-up portion 41 and the manifold 7 to the inlets 65 and 66. The lean mixture generated in the flow path of the rich-lean burner 6 connected to the lean mixture inlet 65 is ejected from the lean flame port 61, and the rich mixture generated in the flow path of the rich-lean burner 6 connected to the rich mixture inlet 66 is ejected from the rich flame ports 62 and 62.

[0025] Reference Figure 1 The multiple rich-lean burners 6 arranged side by side in the combustion chamber 2 are divided into: Figure 1 The combustion system consists of three groups: a first burner group G1 with seven rich / lean burners on the right, a second burner group G2 with four rich / lean burners in the middle, and a third burner group G3 with eight rich / lean burners on the left. Furthermore, changing the combination of burner groups allows for switching the combustion capacity to multiple levels. Specifically, the combustion capacity can be freely switched to: the lowest level (4 burners) that ignites only burner group G2; the second level (7 burners) that ignites only burner group G1; the third level (11 burners) that ignites both burner groups G1 and G2; and the highest level (19 burners) that ignites all burner groups G1, G2, and G3.

[0026] An ignition electrode 8 is mounted on the front surface of the combustion casing 1, facing the upper part of the designated rich-lean burner 6 belonging to the second burner group G2. Furthermore, a flame rod 9 is mounted above the first specific rich-lean burner 61 and the second specific rich-lean burner 62. The first specific rich-lean burner 61 is composed of the rich-lean burner at the left end of the first burner group G1, and the second specific rich-lean burner 62 is adjacent to the left side of the first specific rich-lean burner 61 and is composed of the rich-lean burner at the right end of the second burner group G2. Moreover, even when the combustion capacity is any of the first to fourth capabilities described above, at least one of the first and second specific rich-lean burners 61 and 62 will ignite. Therefore, flame monitoring can be performed using the flame rod 9 even with any of the first to fourth capabilities.

[0027] The following is a detailed description of flame rod 9. (Refer to...) Figure 1 The flame rod 9 has: a first longitudinal rod portion 91, which extends rearward from the front end of the first specific rich-lean burner 61 directly above the light flame opening 61 of the first specific rich-lean burner 61; and a transverse rod portion 92, which extends laterally from the rear end of the first longitudinal rod portion 91 toward the side of the second specific rich-lean burner 62. The end of the transverse rod portion 92 is located directly above the light flame opening 61 of the second specific rich-lean burner 62. The flame rod 9 also has: a second longitudinal rod portion 93, which extends rearward from the end of the transverse rod portion 92 directly above the light flame opening 61 of the second specific rich-lean burner 62.

[0028] Additionally, refer to Figure 3 The device includes a sealing component 67 that seals off the following portions: the portion of the rich flame port 62 of the first and second specific rich-lean burners 61 and 62 located directly below the crossbar portion 92; that is, the portion of the rich flame port 62 on the left side of the first specific rich-lean burner 61 located directly below the crossbar portion 92 and the portion of the rich flame port 62 on the right side of the second specific rich-lean burner 62 located directly below the crossbar portion 92. Therefore, while the flame rod 9 contacts the combustion flame of the lean mixture ejected from the lean flame port 61 of the first and second specific rich-lean burners 61 and 62, it does not contact the combustion flame of the rich mixture ejected from the rich flame port 62 of these specific rich-lean burners 61 and 62. Thus, the excess air ratio of the lean mixture can be detected using the flame rod 9. Additionally, the sealing component 67 has: a pair of plugs 67a, 67a that are inserted into the aforementioned portion of the rich flame port 62 on the left side of the first specific rich-lean burner 61 and the aforementioned portion of the rich flame port 62 on the right side of the second specific rich-lean burner 62; and a pair of connecting portions 67b, 67b that span across the two plugs 67a, 67a.

[0029] Based on the above configuration, the first longitudinal rod portion 91 of the flame rod 9 extends rearward from the front end of the first specific rich-lean burner 61, directly above the light flame port 61 of the first specific rich-lean burner 61. Therefore, the rear end of the first longitudinal rod portion 91 is located directly above the portion of the light flame port 61 that is somewhat removed from the front end of the first specific rich-lean burner 61, making it difficult for flame lift-off to occur. Similarly, the end of the crossbar portion 92 of the flame rod 9 is also located directly above the portion of the light flame port 61 that is somewhat removed from the rear-rear end of the second specific rich-lean burner 62, making it difficult for flame lift-off to occur. Therefore, the rear end of the first longitudinal rod portion 91 and the end of the crossbar portion 92 are highly likely to come into contact with the combustion flame of the lean mixture ejected from the light flame ports 61 of the first and second specific rich-lean burners 61 and 62, thereby improving the reliability of the excess air rate detection of the lean mixture performed by the flame rod 9. Furthermore, in this embodiment, the second longitudinal rod portion 93 provided on the flame rod 9 can come into contact with the combustion flame of the lean mixture ejected from the lean flame port 61 of the second specific lean burner 62 over a large area, thereby further improving the reliability of the detection of the excess air rate of the lean mixture.

[0030] Next, an explanation Figure 4 , Figure 5 The combustion device of the second embodiment is shown. The basic structure of the combustion device of the second embodiment is not particularly different from that of the first embodiment, and the same reference numerals are used for the same parts and locations as in the first embodiment. The main difference between the combustion device of the second embodiment and the first embodiment is that the first longitudinal rod portion 91 of the flame rod 9 extends rearward from the front end of the first specific rich-lean burner 61 to the position of the bridging portion 64a closest to the front end, and the transverse rod portion 92 of the flame rod 9 is located at the position directly above the bridging portions 64a, 64a closest to the front ends of the first and second specific rich-lean burners 61 and 62.

[0031] Here, since the bridging portion 64a blocks the rich flame port 62 from above, the crossbar portion 92 located at the upper part of the bridging portion 64a will not come into contact with the combustion flame of the rich mixture ejected from the rich flame port 62. That is, according to the second embodiment, the blocking component that blocks the portion located at the lower part of the crossbar portion 92 of the flame bar 9 in the rich flame port 62 of the first and second specific rich and lean burners 61 and 62 is composed of the bridging portion 64a closest to the front end of each specific rich and lean burner 61 and 62. As a result, it is not necessary to provide a separate blocking component, which can reduce the number of components and thus reduce costs. In addition, since the bridging portion 64a blocks the lean flame port 61 and the rich flame port 62 from above, no mixture is ejected from the bridging portion 64a. As a result, the ejection velocity of the mixture slows down near the bridging portion 64a, and the combustion flame, especially the combustion flame of the lean mixture, is less likely to detach. Therefore, the first and second longitudinal rod portions 91 and 93 of the flame rod 9 can make more reliable contact with the combustion flame of the lean mixture near the bridging portion 64a, thereby improving the reliability of the excess air rate detection of the lean mixture performed by the flame rod 9.

[0032] While embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited thereto. For example, in the above embodiments, although the first longitudinal rod portion 91 of the flame rod 9 is configured to extend rearward from the front end of the first specific rich-lean burner 61 directly above the light flame port 61 of the first specific rich-lean burner 61, it may also be configured to extend forward from the rear end of the first specific rich-lean burner 61. Furthermore, although the second longitudinal rod portion 93 of the flame rod 9 is a necessary component in the second embodiment described above, it may be omitted in the first embodiment described above.

Claims

1. A combustion device comprising, within a combustion chamber, a plurality of elongated, longitudinally elongated, rich-lean burners, each having a lean flame orifice and a pair of rich flame orifices at its upper end, arranged side-by-side in a transverse direction, wherein, The lean flame nozzle ejects a lean mixture with a fuel concentration even less than the stoichiometric air-fuel ratio. The pair of rich flame nozzles are located on the lateral sides of the lean flame nozzle and eject a rich mixture with a fuel concentration even greater than the lean mixture. The rich and lean burner is divided into multiple burner groups, and the combustion capacity is switched to multiple levels by changing the combination of the burner groups being burned. Two laterally adjacent rich-lean burners among the rich-lean burners are selected as specific rich-lean burners that ignite even with any combustion capacity, at least one of them, and the flame bar is arranged facing upwards towards the two specific rich-lean burners. Its features are, The flame rod has: a first longitudinal section, which extends from one end of the specific rich-lean burner in the front-rear direction toward the other end in the front-rear direction, directly above the light flame nozzle of the specific rich-lean burner; and a transverse section, which extends laterally from the other end of the first longitudinal section toward the other side of the specific rich-lean burner. The end of the crossbar is located directly above the light flame nozzle of the specific rich-lean burner on the other side. The combustion device includes a sealing component for sealing the portion located directly below the crossbar of the flame bar in the rich flame port of each specific rich-lean burner.

2. The combustion device according to claim 1, characterized in that, The flame rod has a second longitudinal rod portion that bends and extends from the end of the crossbar portion toward the other direction in a front-back direction at the upper part of the light flame port of the specific light-dark burner on the other side.

3. The combustion device according to claim 2, characterized in that, Each enrichment / lean burner has: a plurality of front and rear bridging portions spanning between the upper edges of a pair of outer side plates, the pair of outer side plates being located laterally outside the enrichment flame opening on both sides. The crossbar portion of the flame rod is located at the top of the bridging portion closest to one end of the two specific rich and lean burners in the front-rear direction, and this bridging portion is used to form the sealing component.

Images