Combustion device

Abstract

The present application provides a kind of combustion device, which can ensure the accuracy of flame monitoring for a long time without using protective coating to coat the surface of flame rod.The combustion device is configured as follows: multiple burners with main flame ports and side flame ports located on the lateral sides of the main flame ports are arranged side by side in a transverse direction, and the flame rod is arranged above the first and second specific burners that are adjacent in the transverse direction.The flame rod has a first rod portion extending from an insulator to the upper part of the side flame port on the lateral side of the first specific burner, a second rod portion located at the position of the upper part of the side flame port and extending from the end of the first rod portion, a third rod portion extending from the end of the second rod portion to the upper part of the side flame port on the lateral side of the second specific burner, and a fourth rod portion located at the position of the upper part of the side flame port and extending from the end of the third rod portion.

Description

Technical Field

[0001] The present invention relates to a combustion device as described below, wherein multiple burners that are longer in the front-to-back direction are arranged side by side in a transverse direction in a combustion chamber, each burner having a main flame port at its upper end and side flame ports located on both sides of the main flame port. These burners are divided into multiple burner groups, and the combustion capacity can be 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 from a plurality of burners arranged side by side in the combustion chamber, two burners that are laterally adjacent and belong to different burner groups and that at least one of them will burn even at any combustion capacity are selected as specific burners, and a flame bar is arranged facing the top of the two specific burners, and flame monitoring is performed using the flame bar (for example, see Patent Document 1).

[0003] The flame rod is configured to span across the top of the two specific burners. Furthermore, the combustion flame of the mixture ejected from the main flame port of each specific burner, i.e., the main flame, and the combustion flame of the mixture ejected from the side flame port, i.e., the side flame, will come into contact with the flame rod, causing the flame current to flow.

[0004] However, when the main flame remains in contact with the flame rod for a certain period of time, the flame rod will be heated to over 1000°C. Furthermore, once the flame rod is heated to such a high temperature, due to the oxidation of the alloy in which the flame rod is formed (i.e., aluminum alloy), aluminum oxide with low conductivity will precipitate on the surface of the flame rod. As a result, the flame current is difficult to flow, leading to poor flame monitoring accuracy.

[0005] Therefore, it is well known in the past that a protective film made of a material with high conductivity and heat resistance is used to coat the surface of the flame rod (for example, see Patent Document 2). However, according to this configuration, the cost increases significantly due to the formation of the protective film.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2018-119703

[0009] Patent Document 2: Japanese Patent Application Publication No. 2019-19993 Summary of the Invention

[0010] In view of the above-mentioned problems, the present invention aims to provide a combustion device that can ensure the flame monitoring accuracy of the flame rod for a long period of time without using a protective coating to cover the surface of the flame rod.

[0011] To address the aforementioned issues, the combustion device of the present invention comprises multiple burners arranged side-by-side in a transverse direction within the combustion chamber. Each burner has a main flame port at its upper end and side flame ports located transversely on both sides of the main flame port. These burners are grouped into multiple burner groups, and the combustion capacity can be switched to multiple levels by changing the combination of the burning burner groups. From these burners, two burners that are transversely adjacent and belong to different burner groups are selected, and even at any combustion capacity, at least one of them will be burning, as specific burners. The flame bar is arranged facing the top of the two specific burners. The characteristic feature is that one of the two specific burners is designated as the first specific burner, and the other is designated as the second specific burner. The burner has a transverse side extending from the direction from the first specific burner toward the second specific burner, and a transverse side extending from the second specific burner toward the first specific burner. The flame rod has: a first rod portion extending from an insulator penetrating the front and rear walls of the combustion chamber toward the upper part of the side flame opening on the transverse side of the first specific burner; a second rod portion located at the upper part of the side flame opening on the transverse side of the first specific burner and extending from the end of the first rod portion; a third rod portion extending from the end of the second rod portion toward the upper part of the side flame opening on the transverse side of the second specific burner; and a fourth rod portion located at the upper part of the side flame opening on the transverse side of the second specific burner and extending from the end of the third rod portion.

[0012] According to the present invention, the side flame on the lateral side of the first specific burner contacts the second rod portion of the flame rod, and the side flame on the lateral side of the second specific burner contacts the fourth rod portion. Furthermore, the main flame on the main flame ports of the first and second specific burners does not contact the second and fourth rod portions. Therefore, the second and fourth rod portions are not heated to high temperatures. In addition, since the third rod portion of the flame rod is cooled by secondary air flowing in the gap between the first and second specific burners, heat is drawn from the second and fourth rod portions to the third rod portion, thereby suppressing the temperature rise of the second and fourth rod portions. As a result, the precipitation of alumina from the surface of the flame rod is suppressed. Therefore, even without a protective coating to cover the surface of the flame rod, the flame monitoring accuracy of the flame rod can be ensured for a long period.

[0013] However, sometimes due to manufacturing errors of the flame rod, the position of the second rod may shift to one side laterally. As a result, the second rod may be located at a point that deviates laterally from the top of the side flame opening on the lateral side of the first specific burner, which may make it impossible to monitor the flame of the first specific burner.

[0014] Therefore, in this invention, it is preferable that the flame rod further comprises: a fifth rod portion extending from the end of the fourth rod portion toward the upper part of the side flame opening on the lateral side of the first specific burner; and a sixth rod portion extending from the end of the fifth rod portion past the upper part of the side flame opening on the lateral side of the first specific burner to a position further to the other side than the lateral position of the second rod portion. Accordingly, when the second rod portion is offset to the lateral side and located at a position deviating laterally from the upper part of the side flame opening on the lateral side of the first specific burner, the position of the sixth rod portion, which is connected to the second rod portion by means of the third to fifth rod portions, is also offset laterally. Furthermore, the sixth rod portion, located further to the other side than the lateral position of the second rod portion, is positioned at the upper part of the side flame opening on the lateral side of the first specific burner. This allows for monitoring of the flame of the first specific burner.

[0015] Additionally, sometimes the position of the fourth rod is also offset to the other side laterally. In this case, the fourth rod is located at the part that is offset to the other side laterally from the top of the side flame opening of the second specific burner, which may make it impossible to monitor the flame of the second specific burner.

[0016] Therefore, in this invention, it is preferable that the insulator is configured such that the central portion of the insulator through which the flame rod is inserted is located further to the lateral side than the second specific burner, the first rod portion spans above the front and rear ends of the second specific burner, and the front-rear position of the portion of the first rod portion spanning above the front and rear ends of the second specific burner is set such that, when viewed from above, the outline of the front and rear ends is located further forward and backward than the front and rear ends of the main flame opening of the second specific burner, and the outline of the other front and rear ends is located at the same position in the front-rear direction as the front and rear ends of the main flame opening of the second specific burner. Accordingly, even if the fourth rod portion is offset to the other lateral side and located in the portion offset to the other lateral side from the side flame opening of the second specific burner, the end of the main flame of the second specific burner, which extends slightly forward and backward than the front and rear ends of the main flame opening, contacts the first rod portion, thereby enabling monitoring of the flame of the second specific burner. Furthermore, since the outline of the portion of the first rod above the front and rear ends of the second specific burner exists at a position further forward and backward than the front and rear ends of the second specific burner, the main flame only contacts a portion of the portion of the first rod above the front and rear ends of the second specific burner. This prevents the first rod from being heated to a high temperature, which could lead to the precipitation of alumina on its surface.

[0017] Furthermore, to more effectively suppress heating of the first rod portion, it is preferable that the insulator is configured such that its center is positioned laterally, coinciding with the gap between the second specific burner and the burner adjacent to it on its lateral side. The first rod portion has: a longitudinal bar extending directly downward from the insulator; and a transverse bar extending from the lower end of the longitudinal bar across the upper part of the front and rear ends of the second specific burner towards the upper part of the side flame opening on the lateral side of the first specific burner. Accordingly, the flame of any burner will not contact the longitudinal bar portion, and the lower, cooler portion of the main flame will contact the transverse bar portion, thus more effectively suppressing heating of the first rod portion. Attached Figure Description

[0018] Figure 1 This is a top view showing the combustion device according to the first embodiment of the present invention.

[0019] Figure 2 It means along Figure 1 The sectional side view is obtained by cutting along line II-II.

[0020] Figure 3 It means along Figure 1 The cross-sectional view of the key part obtained by cutting along line III-III.

[0021] Figure 4 This is an enlarged top view showing the main parts of the combustion device according to the second embodiment of the present invention.

[0022] Figure 5 It means along Figure 4 The cross-sectional view of the key part is obtained by cutting along line V-V.

[0023] Figure 6 This is an enlarged top view showing the main parts of the combustion device according to the third embodiment of the present invention.

[0024] Figure 7 It means along Figure 6 The cross-sectional view of the key part obtained by cutting along line VII-VII.

[0025] Explanation of symbols in attached drawings

[0026] 2…combustion chamber; 6…burner; 61…first specific burner; 62…second specific burner; 61…main flame inlet; 62…side flame inlet; 9…flame rod; 91…first rod section; 91a…outline of the front and rear sides of the first rod section above the front and rear ends of the second specific burner when viewed from above; 91b…outline of the front and rear sides of the first rod section above the front and rear ends of the second specific burner when viewed from above; 911…longitudinal rod section; 912…transverse rod section; 92…second rod section; 93…third rod section; 94…fourth rod section; 95…fifth rod section; 96…sixth rod section. Detailed Implementation

[0027] 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 pipe 5, and air is supplied to the air supply chamber 3 from the combustion fan. The partition plate 4 has multiple distribution holes 4a located at the arrangement intervals of the burner 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.

[0028] Inside the combustion chamber 2, multiple burners 6, which are relatively long in the front-to-back direction, are arranged side by side in a transverse direction. Each burner 6 has the following features at its upper end: Figure 3The main flame port 61 is shown, and the side flame ports 62, 62 are located on both sides of the main flame port 61. In addition, in this embodiment, the burner 6 is composed of a lean-rich burner, which sprays a lean mixture with a fuel concentration lower than the stoichiometric air-fuel ratio from the main flame port 61, and a rich mixture with a fuel concentration higher than the lean mixture from each of the side flame ports 62.

[0029] A flow straightening component 63 is installed within the main flame port 61. This flow straightening component 63 has multiple flow straightening plates 63a that divide the main flame port 61 into multiple regions laterally. Throttling sections 63b are provided at multiple locations before and after the flow straightening component 63, ensuring close lateral contact between the multiple flow straightening plates 63a and thus dividing the main flame port 61 into multiple sections laterally. Additionally, recirculation regions 61a, which do not eject mixed gas, are provided on both sides of the main flame port 61, located between it and each side flame port 62. Each burner 6 also has a bridging section 64a spanning between the upper edges of a pair of outer plates 64, 64 and located in the same front-rear direction as the throttling section 63b of the flow straightening component 63. These outer plates 64, 64 are located laterally outside the side flame ports 62, 62 on both sides.

[0030] Reference Figure 2 Each burner 6 has a main flame inlet 65 and a side flame inlet 66 located above it at its lower front end. Additionally, a raised portion 41 is formed by bending at the leading edge of the partition plate 4, and a manifold 7 is installed on the front side of the raised portion 41 to block the lower front surface of the combustion chamber 1. The raised portion 41 has openings facing the inlets 65 and 66 of each burner 6, and an air conditioning plate 42 with openings corresponding to the inlets 65 and 66 of each burner 6 is installed on the front surface of the raised portion 41. The manifold 7 is equipped with gas nozzles 71 and 72 for the main flame and side flame, respectively, opposite to the inlets 65 and 66 of each 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 burner 6. Primary air is supplied from the air supply chamber 3 through the gap between the riser 41 and the manifold 7 to the inlets 65 and 66 of the burner 6. Furthermore, the lean mixture generated in the flow path within the burner 6 connected to the main flame inlet 65 is ejected from the main flame port 61, and the rich mixture generated in the flow path within the burner 6 connected to the side flame inlet 66 is ejected from the side flame ports 62 and 62.

[0031] Reference Figure 1 It consists of multiple burners arranged side by side in combustion chamber 2, comprising: Figure 1The combustion system consists of four burners (6) on the right side (Group 1) and eight burners (6) on the left side (Group 2). Furthermore, by changing the combination of the desired burner groups, the combustion capacity can be switched to multiple levels. Specifically, the combustion capacity can be freely switched to: Level 1 (4 burners) where only Burner Group G1 burns; Level 2 (8 burners) where only Burner Group G2 burns; and Level 3 (12 burners) where both Burner Groups G1 and G2 burn.

[0032] A spark plug 8 is installed on one of the chamber walls in front of or behind the combustion chamber 2, for example, on the front chamber wall 21. This spark plug 8 faces upwards near the front end of a designated burner 6 belonging to the second burner group G2. Furthermore, a flame rod 9 is installed facing upwards towards the first specific burner 61 and the second specific burner 62. The first specific burner 61 is composed of the burner at the right end of the second burner group G2, and the second specific burner 62 is adjacent to the right side of the first specific burner 61 and is composed of the burner at the left end of the first burner group G1. Moreover, even when the combustion capacity is at any of the first to third capabilities mentioned above, at least one of the first and second specific burners 61 and 62 will ignite. Therefore, flame monitoring can be performed using the flame rod 9 even at any of the first to third capabilities.

[0033] Next, the flame rod 9 will be described in detail. Furthermore, in the following description, the direction from the first specific burner 61 towards the second specific burner 62 will be considered one lateral side, and the direction from the second specific burner 62 towards the first specific burner 61 will be considered the other lateral side. (Refer to...) Figure 1 , Figure 3 The flame rod 9 has: a first rod portion 91, which extends from the insulator 90 penetrating the chamber wall 21 in front of the combustion chamber 2 towards the lateral side of the first specific burner 61 ( Figure 1 Right side of the middle Figure 3 The second rod 92 extends diagonally downward from the upper part of the side flame opening 62 on the lateral side of the first specific burner 61; the third rod 93 extends from the end of the second rod 92 towards the other lateral side of the second specific burner 62. Figure 1 Left side of the middle Figure 3 The third rod 93 extends from the upper part of the side flame opening 62 on the right side of the second burner 62; and the fourth rod 94 is located at the upper part of the side flame opening 62 on the other side of the second burner 62 and extends from the end of the third rod 93.

[0034] The insulator 90 is configured such that the center portion of the insulator through which the flame rod 9 passes is located further to the lateral side than the second specific burner 62. Specifically, the insulator 90 is configured such that the center portion of the insulator is in a lateral position that corresponds to the gap between the second specific burner 62 and the burner 6 adjacent to it on the same lateral side. Furthermore, the first rod portion 91 extends across the front end of the second specific burner 62. In addition, the front-rear position of the portion of the first rod portion 91 extending across the front end of the second specific burner 62 is set such that, when viewed from above, the front outline 91a is located further forward than the front end of the main flame port 61 of the second specific burner 62, and the rear outline 91b is located at the same position in the front-rear direction as the front end of the main flame port 61. In addition, "at the same position in the front-rear direction as the front end of the main flame port 61" includes the case where it is located slightly forward or backward than the front end of the main flame port 61.

[0035] According to this embodiment, the side flame on the side flame port 62 on the lateral side of the first specific burner 61 contacts the second rod portion 92 of the flame rod 9, and the side flame on the side flame port 62 on the other lateral side of the second specific burner 62 contacts the fourth rod portion 94. Furthermore, the main flame on the main flame port 61 of the first and second specific burners 61 and 62 does not contact the second and fourth rod portions 92 and 94. Therefore, the second and fourth rod portions 92 and 94 are not heated to temperatures exceeding 1000°C. Moreover, the third rod portion 93 of the flame rod 9 is cooled by secondary air flowing through the gap between the first and second specific burners 61 and 62. As a result, heat is drawn from the second and fourth rod portions 92 and 94 to the third rod portion 93, effectively suppressing the temperature rise of the second and fourth rod portions 92 and 94. Consequently, the precipitation of alumina from the surface of the flame rod 9 is suppressed. Therefore, even without coating the surface of the flame rod 9 with a protective film, the flame monitoring accuracy of the flame rod 9 can be ensured for a long time. As a result, compared with using a protective film to coat the surface of the flame rod 9, a significant cost reduction can be achieved.

[0036] However, sometimes due to machining errors in the flame rod 9, the position of the fourth rod portion 94 may shift laterally to the other side, causing the fourth rod portion 94 to be located at a portion offset laterally from the upper part of the side flame opening 62 on the other side of the second specific burner 62. Even in this case, in this embodiment, the end of the main flame of the second specific burner 62, which extends slightly forward from the front end of the main flame opening 61, contacts the first rod portion 91, thereby enabling monitoring of the flame of the second specific burner 62.

[0037] Furthermore, since the outline 91a of the portion of the first rod 91 above the front end of the second specific burner 62 exists at a position further forward than the front end of the main flame port 61, the main flame only contacts a portion of the portion of the first rod 91 above the front end of the second specific burner 62. This prevents the first rod 91 from being heated to a high temperature, which could lead to the precipitation of alumina on its surface.

[0038] Next, an explanation Figure 4 , Figure 5 The second embodiment is shown. The basic structure of the second embodiment is not particularly different from the first embodiment described above, and the same components and parts as in the first embodiment are given the same reference numerals as described above. The difference between the second embodiment and the first embodiment lies in the following aspect: the flame rod 9 has a fifth rod portion 95, which extends from the end of the fourth rod portion 94 toward the lateral side of the first specific burner 61 (…). Figure 4 On the right side, Figure 5 The sixth rod 96 extends from the end of the fifth rod 95, passing over the top of the side flame opening 62 on the lateral side of the first specific burner 61, and extends further to the other lateral side than the lateral position of the second rod 92. Figure 4 On the left side, Figure 5 The portion located on the right side of the first specific burner 61, specifically, extends to the upper part of the recirculation region 61a adjacent to the side flame opening 62 on the lateral side of the first specific burner 61.

[0039] Accordingly, if the second rod portion 92 is misaligned to one side due to a manufacturing error, thus shifting its position from directly above the side flame opening 62 on the lateral side of the first specific burner 61, the position of the sixth rod portion, which is connected to the second rod portion via the third to fifth rod portions 93 to 95, also shifts to one side. Furthermore, the sixth rod portion 96, located further to the other side than the lateral position of the second rod portion 92, is positioned directly above the side flame opening 62 on the lateral side of the first specific burner 61. This allows for monitoring of the flame of the first specific burner 61. Furthermore, even if the fourth rod portion 94 is located at the part that is offset to the other side of the side flame opening 62 from the other side of the second specific burner 62 due to the misalignment to the other side, the end of the main flame of the second specific burner 62 that extends slightly forward from the front end of the main flame opening 61 will contact the first rod portion 91, just like in the first embodiment described above, thereby enabling the monitoring of the flame of the second specific burner 62.

[0040] Next, we will explain the shape of the first rod portion 91 of the flame rod 9, which differs from the first and second embodiments described above. Figure 6 , Figure 7 The third embodiment is shown. In the third embodiment, similarly to the first and second embodiments, the insulator 90 is configured such that the center of the insulator is located on the same lateral side as the second specific burner 62. Figure 6 Right side of the middle Figure 7 The first rod portion 91 has a longitudinal rod portion 911 that extends directly downward from the insulator 90; and a transverse rod portion 912 that extends from the lower end of the longitudinal rod portion 911 across the upper front end of the second specific burner 62 toward the transverse side of the first specific burner 61. Figure 6 Right side of the middle Figure 7 The flame vent 62 of the side fire extends directly above the left side of the center.

[0041] Furthermore, the position of the first rod portion 91 above the front end of the second specific burner 62, i.e., the crossbar portion 912, in the front-rear direction is set in the same manner as in the first and second embodiments: when viewed from above, the front outline 91a is located at a position on the second specific burner 62 that is further forward than the front end of the main flame port 61, and the rear outline 91b is located at the same position in the front-rear direction as the front end of the main flame port 61. Additionally, although the flame rod 9 has 2 to 6 rod portions 92 to 96 in the same manner as in the second embodiment, the 5th and 6th rod portions 95 and 96 may be omitted.

[0042] According to the third embodiment, the flame of any burner 6 will not come into contact with the longitudinal bar portion 911 of the first rod portion 91. In addition, the lower part of the main flame of the second specific burner 62, which extends slightly forward from the front end of the main flame port 61, which has a lower temperature, comes into contact with the transverse bar portion 912. Therefore, the heating of the first rod portion 91 can be suppressed more effectively.

[0043] 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, the insulator 90 may penetrate the rear wall of the combustion chamber 2. In this case, the first rod portion 91 extends over the rear end of the second specific burner 62. Furthermore, the front-rear position of the portion of the first rod portion 91 extending over the rear end of the second specific burner 62 is set such that, when viewed from above, the rear outline of this portion is located further rearward than the rear end of the main flame port 61 of the second specific burner 62, and the front outline is located at the same position in the front-rear direction as the rear end of the main flame port 61.

[0044] Furthermore, in the first and second embodiments described above, the insulator 90 may also be configured such that its center is located further to the lateral side than the burner 6 adjacent to the lateral side of the second specific burner 62, or that its center is located between the first specific burner 61 and the second specific burner 62. Additionally, the burner 6 may be a burner other than a rich-lean burner.

Claims

1. A combustion device comprising: a plurality of long burners arranged side-by-side in a transverse direction within a combustion chamber; each burner having a main flame port at its upper end and side flame ports located on either side of the main flame port; the burners being grouped into multiple burner groups; and the combustion capacity being switched to multiple levels by changing the combination of the burner groups being burned. From these burners, two burners that are laterally adjacent and belong to different burner groups, and that at least one burns even at any combustion capacity, are selected as specific burners. The flame bar is then arranged facing the top of the two specific burners. Its features are, Designating one of the two specific burners as the first specific burner and the other as the second specific burner, the direction from the first specific burner towards the second specific burner is defined as one lateral side, and the direction from the second specific burner towards the first specific burner is defined as the other lateral side. The flame rod has: a first rod portion extending from an insulator penetrating one side of the combustion chamber wall toward the upper part of the side flame opening on the lateral side of the first specific burner; a second rod portion located at the upper part of the side flame opening on the lateral side of the first specific burner and extending from the end of the first rod portion; and a third rod portion extending from the end of the second rod portion toward the upper part of the side flame opening on the other lateral side of the second specific burner. And the fourth rod, which is located directly above the side flame opening on the other side of the second specific burner and extends from the end of the third rod.

2. The combustion device according to claim 1, characterized in that, The flame rod also has: a fifth rod portion that extends from the end of the fourth rod portion toward the upper part of the side flame opening on the lateral side of the first specific burner; And the 6th rod, which extends from the end of the 5th rod across the top of the side flame opening on the lateral side of the 1st specific burner to a position further laterally than the lateral position of the 2nd rod.

3. The combustion device according to claim 1 or 2, characterized in that, The insulator is configured such that the center of the insulator through which the flame rod is inserted is located further laterally than the second specific burner. The first rod portion spans above the front and rear ends of the second specific burner. The front-rear position of the portion of the first rod portion spanning above the front and rear ends of the second specific burner is set such that, when viewed from above, the outline of the front and rear ends is located further forward and backward than the front and rear ends of the main flame port of the second specific burner, and the outline of the other front and rear ends is located at the same position in the front-rear direction as the front and rear ends of the main flame port of the second specific burner.

4. The combustion device according to claim 3, characterized in that, The insulator is configured such that its center is positioned laterally in a manner consistent with the gap between the second specific burner and the burner adjacent to it on the same lateral side. The first rod portion has: a longitudinal rod portion extending directly downward from the insulator; and a transverse rod portion extending from the lower end of the longitudinal rod portion across the upper part of the front and rear ends of the second specific burner toward the upper part of the side flame opening on the transverse side of the first specific burner.

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