JP4340873B2 - Combustion device - Google Patents

Description

  The present invention relates to a gas having a high Wobbe Index (WI) such as city gas (for example, 13A gas) or LPG (hereinafter referred to as “high WI gas” in this specification) and reforming supplied to a fuel cell. A hydrogen-containing gas having a low Wobbe index (hereinafter referred to as “low WI gas” in this specification), such as a gas (process gas) or a hydrogen-based gas (off-gas) that remains unused when power is generated by a fuel cell. In particular, the present invention relates to a technique for reducing NOx emissions while avoiding the disadvantages of burning two kinds of gases.

  2. Description of the Related Art Conventionally, a combustion apparatus configured in a premixing system in which high WI gas and low WI gas are mixed in advance and then jetted into a combustion space and burned is known (see, for example, Patent Document 1). That is, first, a high WI gas and air are premixed, and further, off-gas of the fuel cell is mixed as a low WI gas to form a premixed gas, which is then ejected from a flame hole and burned.

JP 2002-213710 A

  However, in the premixing system disclosed in Patent Document 1, the low WI gas containing a large amount of hydrogen is premixed with air and burned. In this way, the combustion speed becomes extremely high, and the flashback Inconvenience is likely to occur.

  In view of this, the present applicant has proposed in Japanese Patent Application No. 2002-189126 a combustion apparatus configured to supply high WI gas and low WI gas separately to the combustion space and to different portions of the combustion space.

  However, although the proposed combustion apparatus can achieve stable combustion of the above two types of gases, it has been found that there is a possibility that the concentration of generated NOx becomes considerably high. That is, the fuel cell off-gas (hereinafter simply referred to as “off-gas”), which is a low WI gas, is ejected from the position upstream of the flame hole position where the high WI gas preliminarily mixed with air is burned into the combustion space. As a result, the off-gas is introduced into the combustion atmosphere of the high WI gas, and the combustion temperature becomes higher than when only the high WI gas is combusted with air. As a result, the NOx concentration is increased. It is thought to be higher.

  The present invention has been made in view of such circumstances. The object of the present invention is to eliminate NOx emissions while avoiding inconveniences when both high WI gas and low WI gas are burned. An object of the present invention is to provide a combustion apparatus capable of reducing the amount.

In order to achieve the above object, in the invention according to claim 1 , the fuel gas supplied from the fuel gas supply system is the first gas having a high Wobbe index, and the hydrogen-containing gas generated in the fuel cell is a low Wobbe index. As the second gas, the following specific matters are provided for a combustion apparatus that burns both the first gas and the second gas in the combustion space. Sunawa Chi, primary combustion chamber, and a secondary combustion chamber on the downstream side, the first gas concentration lower than the theoretical combustion air amount is air concentration on the upstream side which communicates with each other with respect to the vertical flow direction of the combustion space a burner ports face a primary flame is formed in the primary combustion chamber above high over-rich mixture is incomplete combustion flame is supplied with said a downstream position than the primary flame formed in the fire hole surface In the secondary combustion chamber, an air ejection part for blowing secondary air to the combustion gas generated from the primary flame, and an opening at a position downstream of the air ejection part, and blowing out secondary air from the air ejection part in the unburned components contained in the combustion gas Ru are secondary combustion toward the two-Tsugi燃 combustion chamber e Bei a second gas discharging part that discharges said second gas, said secondary combustion chamber by, At the same time as the unburned component is subjected to secondary combustion, the second gas discharge Second gas discharged from the section has a configuration in which the secondary flame is diffused combustion is formed. Here, the above-mentioned “fuel gas” is a city gas supplied from a fuel gas supply system or a fuel gas which is a high WI gas to be combusted in a normal combustion apparatus such as LPG. “Hydrogen-containing gas” is a process gas mainly comprising hydrogen supplied to the fuel cell and / or hydrogen that remains unused and is discharged from the anode electrode during power generation by the fuel cell. It is a hydrogen-containing gas that is a low WI gas such as off-gas.

For the invention according to claim 1 above, for rich mixture of the first gas and air is burned in incomplete combustion state in the burner ports face, unburned from the primary flame is formed on the burner port surface Combustion gas containing a lot of components flows downstream of the combustion space. And the combustion gas which flowed to this downstream receives the blow-off of the secondary air from the said air ejection part, and the unburned component contained in the combustion gas is subjected to secondary combustion. At this time, the second gas is discharged from the second gas discharge portion to the secondary combustion region, and the secondary combustion is performed together with the unburned components. That is, although the first gas is premixed combustion in the first stage, it is incompletely combusted by making it a rich mixture, while the second gas is in the second stage and the unburned components of the first gas and two It is burned without causing backfire by diffusion combustion with the secondary air. As described above, the first gas can be primarily burned in the range where the combustion temperature does not become so high on the upstream side of the combustion space, and the second gas can be completely burned together with the unburned components on the downstream side of the combustion space. Thus, reduction of NOx emissions Ru achieved. More specifically, the first gas having a high Wobbe index can be primarily burned in the primary combustion chamber in a rich mixture state, that is, the combustion temperature becomes excessively high without being mixed with the second gas. The primary combustion can be performed in a low NOx emission state that avoids this, and the unburned unburned components are secondarily burned together with the second gas in the secondary combustion chamber by the secondary air from the air ejection section, and are completely burned. Thereby, the NOx emission amount can be reduced, and the second gas supplied and discharged to the second gas discharge section without premixing at the time of the secondary combustion. Can be burned simultaneously by diffusion combustion, and even if the second gas is a gas having a low Wobbe index containing a large amount of hydrogen, there is no inconvenience such as the occurrence of flashback.

  The “rich mixture with an air concentration lower than the theoretical combustion air amount and a high first gas concentration” means that the excess air ratio is less than 1.0, and the theoretical combustion air amount necessary for complete combustion. As long as it is a rich air-fuel mixture containing an insufficient amount of air and is combustible, the amount of air may be zero, that is, the first gas itself containing no air may be used. Preferably, a premixed gas having an excess air ratio of around 0.5 and at least a flammable limit is used.

In the combustion apparatus according to the first aspect, by selectively adding the following various specific items, the combustion apparatus can be more specifically specified to obtain the action of each invention more specifically. It becomes possible to obtain a new action.

That is, firstly, the flame hole surface is disposed at a position closer to the outside in the combustion space, the air ejection part is disposed at a position closer to the inner side than the flame hole surface, and the second gas discharge part is provided. It arrange | positions so that it may open to a downstream position rather than the said air ejection part (Claim 2 ). In this case, the combustion gas flows downstream from the primary flame formed on the flame hole surface on the outer side, and the secondary air is blown out from the air ejection portion on the inner side with respect to this combustion gas, and the secondary combustion Is generated toward the downstream side, and the second gas is discharged into the secondary combustion flame and burned. With respect to this configuration, the air jetting unit flows the combustion gas flow from the primary flame so as to face the flame hole surface from the position downstream of the flame hole surface toward the combustion space. A guide wall that guides to the side may be further provided (claim 3 ). By doing in this way, since the combustion gas which arises from a primary flame is induced | guided | derived toward an air ejection part by an induction | guidance | derivation wall, secondary air is blown out with respect to all the combustion gases, and mixing of both is accelerated | stimulated. As a result, it is possible to more surely realize the complete combustion of all the unburned components together with the second gas by avoiding the possibility that the unburned components are discharged without being subjected to secondary combustion, and NOx emission The amount can be reduced more reliably.

A second, second gas from the second gas discharging part to set the orientation of the opening to be discharged in a direction intersecting with respect to the vertical flow direction of the combustion space (Claim 4). In this case, the second gas is discharged from the direction intersecting the flame of the secondary combustion generated toward the downstream side by blowing out the secondary air from the air ejection portion, and the second gas is completely combusted. Can be realized more reliably.

Thirdly, it further includes ignition means disposed so as to protrude into the combustion space from a partition wall that defines the combustion space, and cooling means for cooling the ignition means, and the cooling means is used for cooling. air and configured to blown towards the base located on the partition wall side of the said ignition means (claim 5). In this case, since the cooling air is blown out toward the base located near the partition wall rather than toward the combustion space, a flame such as secondary combustion formed on the combustion space is disturbed. While avoiding this, it is possible to avoid the temperature of the ignition means from being excessively increased by being burned by the flame and to ensure its thermal durability.

Fourth, it further comprises a flame detection means arranged to project into the combustion space from the partition wall that defines the combustion space, and a cooling means for cooling the flame detection means. The cooling air is blown out toward the base located near the partition wall of the flame detection means (claim 6 ). Even in this case, the cooling air is blown not toward the combustion space but toward the base located near the partition wall, so that a flame such as secondary combustion formed on the combustion space is disturbed. This prevents the flame detection means from being burned by the flame and excessively rises in temperature while avoiding being burned, and can ensure its thermal durability.

Here, in the third or fourth specific matter described above, the cooling means further includes a configuration in which cooling air is blown from the position of the partition wall inner surface along the inner peripheral surface of the partition wall (Claim 7 ). You may make it add. By doing so, the blown air flows along the inner peripheral surface of the partition wall that is the outer periphery of the combustion space to form a swirling air flow. In addition to cooling of the ignition means or flame detection means, the swirling air layer along the circumferential surface prevents the temperature of the partition wall from excessively rising by protecting the wall surface of the partition wall from flames such as secondary combustion. Become. Moreover, unlike the conventional cooling means that blows cooling air toward the combustion space, a small amount of air that only forms a swirling air layer is required, so the amount of air blown that does not contribute to combustion is reduced. Reduction can also be achieved.

As described above, according to any one of claims 1 to 7 , the first gas is premixed combustion in the first stage, but is incompletely combusted by using a rich mixture. In the second stage, the second gas can be combusted together with the unburned component of the first gas and the secondary air without causing backfire by diffusion combustion. As a result, the first gas can be primarily burned in the range where the combustion temperature does not become too high on the upstream side of the combustion space, and the second gas can be completely burned together with the unburned components on the downstream side of the combustion space. while both complete combustion of gas and a second gas, Ru can achieve a reduction in NOx emissions. More specifically, the first gas having a high Wobbe index can be primarily burned in the primary combustion chamber in a rich mixture state, that is, the combustion temperature becomes excessively high without being mixed with the second gas. The primary combustion can be performed in a low NOx emission state that avoids this, and the unburned unburned components are secondarily burned together with the second gas in the secondary combustion chamber by the secondary air from the air ejection section, and are completely burned. Thereby, the NOx emission amount can be reduced, and the second gas supplied and discharged to the second gas discharge section without premixing at the time of the secondary combustion. Can be burned simultaneously by diffusion combustion, and even if the second gas is a gas having a low Wobbe index containing a large amount of hydrogen, there is no inconvenience such as the occurrence of flashback.

In particular, according to claim 2 , it is possible to more specifically identify the mutual positional relationship between the flame hole surface, the air ejection portion, and the second gas discharge portion, and the first gas and the second gas It is possible to provide more specifically a combustion apparatus capable of completely burning both to achieve a low NOx emission amount. In this case, according to the third aspect , since the combustion gas generated from the primary flame is guided toward the air blowing portion by the guide wall, the secondary air is blown out to all of the combustion gas to promote the mixing of both. It is possible to completely burn all of the unburned components together with the second gas while avoiding the risk that the unburned components are discharged without secondary combustion. As a result, the reduction of the NOx emission amount can be realized more reliably.

According to the fourth aspect , since the second gas is discharged in a direction intersecting the upstream and downstream directions of the combustion space, complete combustion of the second gas can be realized more reliably.

According to claim 5 , the cooling means blown out from the cooling means can cool the ignition means without disturbing the flame such as secondary combustion formed on the combustion space side, and its thermal durability. Can be secured.

According to the sixth aspect , the flame detection means can be cooled by the cooling air blown out from the cooling means without disturbing the flame such as secondary combustion formed on the combustion space side, and its thermal durability. Sex can be secured.

According to the seventh aspect, the swirling air layer can be formed along the inner peripheral surface of the partition wall that is the outer periphery of the combustion space by the cooling air blown out from the cooling means. In addition to the cooling of the ignition means of Item 5 or the flame detection means of Claim 6 , the wall surface of the partition wall can be protected from flames such as secondary combustion, and an excessive temperature rise of the partition wall can be reliably avoided. In addition, unlike the conventionally employed cooling means in which cooling air is blown out toward the combustion space, it is possible to reduce the amount of air blown that does not contribute to combustion.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 shows in principle a combustion apparatus according to an embodiment of the present invention. In the figure, reference numeral 2 denotes a combustion space. A flame hole surface 3 is disposed at a position closer to the outer side facing the combustion space 2, and the air ejection portion 4 and the air injection part 4 are positioned at a position closer to the inner side than the flame hole surface 3. The second gas discharge part 5 is disposed so as to protrude a predetermined amount toward the downstream side (upper side in the figure) of the combustion space 2. And the guide wall 6 is arrange | positioned in the position which opposes the said flame hole surface 3 so that it may protrude. The above "outside position" and "inside position" mean that if the combustion apparatus is cylindrical, the air ejection part 4 and the second gas discharge part 5 are arranged at the center side position that is the inner circumference side thereof. In other words, the flame hole surface 3 is disposed on the outer peripheral side so as to surround this, and if the combustion device is a rectangular tube having a rectangular shape in plan view, the air ejection part 4 and the That is, the two gas discharge portions 5 are disposed, and the flame hole surfaces 3 are disposed at both outer positions with the gas discharge portions 5 interposed therebetween. Hereinafter, the case where the combustion apparatus is configured in a cylindrical shape will be described, and the upstream side of the combustion space 2 will be described as the lower side in FIG. 1 and the downstream side as the upper side in FIG.

  The combustion space 2 is partitioned by a cylindrical partition wall 21, and a heating target (not shown) is disposed on the upper end side (downstream end side). The air ejection part 4 and the second gas discharge part 5 are provided with a large-diameter cylinder 41 to which air is supplied from the upstream side, and is arranged so as to penetrate through the inside of the large-diameter cylinder 41. Hydrogen is supplied as the second gas from the upstream side. It is formed by an inner and outer double pipe from a small diameter cylinder 51 to which a low WI gas is supplied. That is, the air ejection part 4 is composed of a plurality of ejection openings 42, 42,... That open upward from the front end surface (upper end surface) of the large-diameter cylinder 41, and the second gas discharge part 5 It is composed of a plurality of discharge ports 52, 52,... That open from the outer peripheral surface of the distal end portion of the small-diameter cylinder 51 disposed so as to protrude a predetermined amount above the diameter cylinder 41 toward the outer periphery. That is, each outlet 42 of the air ejection part 4 is opened to blow secondary air toward the downstream side of the combustion space 2, while each outlet 52 of the second gas discharge part 5 is in the combustion space. 2 is opened so as to discharge the second gas toward the side perpendicular to the upstream / downstream direction, and the flow directions of the secondary air and the second gas intersect each other. The air ejection part 4 is positioned on the downstream side of the front end of a primary flame 32 described later formed on the flame hole surface 3.

  Examples of the second gas include off-gas discharged from the anode electrode of the fuel cell system. In addition to such off-gas or in place of off-gas, a part of the process gas supplied to the fuel cell may be used.

  The guide wall 6 is formed in the shape of an inner peripheral flange that protrudes from the inner peripheral surface of the partition wall 21 at substantially the same position as the air ejection portion 4 in the upstream and downstream direction of the combustion space 2. A narrowed portion 22 is formed between the leading edge and the large diameter cylinder 41 of the air ejection portion 4. The induction wall 6 divides the combustion space 2 into a primary combustion chamber 23 that communicates with each other through the narrowed portion 22 and a secondary combustion chamber 24 that is a secondary combustion region. That is, the primary combustion chamber 23 is substantially partitioned by the guide wall 6, the flame hole surface 3 opposed to the guide wall 6, the outer peripheral surface of the large diameter tube 41, and the inner peripheral surface of the partition wall 21. become.

  The flame surface 3 is premixed with a fuel gas (for example, city gas 13A), which is a high WI gas, as a first gas supplied from a fuel gas supply system (not shown) and a predetermined over-rich mixture. .. Are supplied, and primary flames 32, 32,..., Which are incomplete combustion flames, are formed in the primary combustion chamber 23 in each flame hole 31 by the primary combustion by the rich mixture. ing. As the above-mentioned predetermined rich mixture, the excess air ratio is less than 1.0 (100%), preferably the excess air concentration is high near the flammability limit and the excess air ratio is set to be close to 0.5. An air-fuel mixture is supplied, and combustion gas containing a large amount of unburned components is generated from the primary flame 32. The combustion gas is guided by the guide wall 6 and passes through the narrowed portion 22 to flow toward the air ejection portion 4, and secondary air blows out from each ejection port 42 of the air ejection portion 4 to the flowing combustion gas. Is done. Upon receiving this secondary air, unburned components in the combustion gas are combusted (secondary combustion), and at the same time, the second gas discharged from each discharge port 52 of the second gas discharge unit 5 is diffused by the secondary air. By burning, a secondary flame 45 is formed in the secondary combustion chamber 24. In addition, instead of the above rich mixture, the fuel gas itself without premixing air may be supplied to the flame hole surface 3 to cause primary combustion. Also in this case, the two-stage combustion in the present embodiment can be applied only by increasing the unburned components in the combustion gas.

  In the above combustion apparatus, the first gas that is a high WI gas in the primary combustion chamber 23 can be primarily burned in the primary combustion chamber 23 in the state of the rich mixture, that is, without being mixed with the second gas. Primary combustion can be performed in a low NOx emission state that avoids an excessively high combustion temperature. Then, the unburned unburned components can be burnt and burnt completely together with the second gas in the secondary combustion chamber 24 by the secondary air from the air jet section 4. Thereby, reduction of NOx emission amount can be achieved. In addition, during the secondary combustion, the second gas supplied and discharged to the second gas discharge unit 5 without being premixed can be simultaneously burned by diffusion combustion, and the second gas generates a large amount of hydrogen. Even if it contains low WI gas, there will be no inconvenience such as backfire.

  Further, since the downstream side of the flame hole surface 3 is covered by the guide wall 6, the extension of the primary flames 32, 32,... Is suppressed, and only the combustion gas is guided to the air ejection part 4. The secondary air from the air ejection part 4 can be blown out only with respect to the combustion gas. That is, the guide wall 6 separates / blocks the direct contact between the secondary air from the air ejection portion 4 and the flame hole flames 32, 32,... And the combustion generated from the primary flames 32, 32,. A function of guiding the flow of gas so as to cross the secondary air blown out from the air blowing portion 4 is exhibited. Further, the separation / blocking function avoids an increase in NOx caused by direct contact of the secondary air with the primary flames 32, 32,..., And contributes to a reduction in NOx. Mixing of combustion gas and secondary air can be promoted while suppressing turbulence.

  In the first embodiment, the air outlets 25, 25,... Provided in the partition wall 21 immediately downstream of the guide wall 6 are slightly directed toward the inner peripheral side of the combustion space 2 (secondary combustion chamber 24). By blowing out an amount of air, it is possible to cool the guide wall 6 itself burned by the primary flame 32, and at the same time, the secondary flame 45 is separated from the partition wall 21 so that the partition wall 21 does not become excessively hot. Can be.

  Moreover, only the second gas can be burned without using the first gas by using the combustion apparatus of the first embodiment. That is, in a state where the supply of the first gas to the flame hole surface 3 is stopped by closing the opening / closing means such as the opening / closing valve, the supply of air to the air ejection part 4 and the supply of the second gas to the second gas discharge part 5 are performed. The second gas can be diffused and combusted by supplying and igniting by the igniting means 7 (see the diffusion combustion flame of reference numeral 53 in FIG. 1).

Second Embodiment
FIG. 2 shows an example in which the combustion apparatus of the present invention is applied specifically to a reformer burner provided in a reformer of a fuel cell system. The combustion apparatus of the second embodiment is the same as that of the first embodiment in the principle of two-stage combustion. In addition, the same code | symbol as 1st Embodiment is attached | subjected to the element equivalent to 1st Embodiment, and the detailed description is abbreviate | omitted.

  In the second embodiment, a double cylindrical partition wall having an inner peripheral partition wall 21a and an outer peripheral partition wall 21b each having a bottom is provided, and air is supplied to the outer peripheral partition wall 21b. The pipe 81 is communicated so that air from the air supply pipe 81 is supplied to the annular space 82 and the bottom space 83 between the inner and outer peripheral side partition walls 21a and 21b. As shown in FIG. 3, the bottom side of the inner peripheral side partition wall 21 a is partitioned into a swirl mixing chamber 91 on the outer periphery side having a partition wall 90 and a mixture distribution chamber 92 on the inner peripheral side of the swirl mixing chamber 91. A predetermined rich air-fuel mixture is supplied from the air-fuel mixture distribution chamber 92 to the flame hole surface 3.

  The swirl mixing chamber 91 is connected to the supply nozzle 9 of the city gas as the first gas through the opening 84 on the upstream side. When the first gas is supplied from the supply nozzle 9 to the swirl mixing chamber 91, the first implementation is performed. A predetermined amount of air is entrained from the bottom side space 83 through the gap of the opening 84 so as to be the same rich mixture as described in the embodiment. The first gas and air supplied to the swirl mixing chamber 91 are premixed while swirling in the circumferential direction (one turn counterclockwise in FIG. 3), and the premixed over-rich mixture is on the downstream side. From the communication port 93 (see FIG. 3), the gas mixture enters the gas mixture distribution chamber 92 and is distributed and supplied to each flame hole of the flame hole surface 3. Further, air is supplied from the bottom side space 83 to the large-diameter cylindrical portion 41 through an annular gap 85 on the inner peripheral side.

  As shown in a detailed example in FIG. 4, the flame hole surface 3 protrudes in a trapezoidal shape toward the primary combustion chamber 23, and the decompression wall 33 is separated from the large-diameter cylinder 41 constituting the air ejection portion 4 by a gap. It is formed to rise downstream. Are formed as primary flame holes on the top wall of the trapezoidal flame hole surface 3, and auxiliary flame holes 31a, 31a are formed on both oblique wall surfaces. A main flame (primary flame) 32 is formed in the flame hole 31. Further, in the deceleration gap sandwiched between the inclined wall surface on the outer peripheral side and the partition wall 21a, the auxiliary flame 32a is formed by a small amount of the rich mixture from the auxiliary flame hole 31a and a small amount of air from the air port 26 of the partition wall 21a. Is formed in the deceleration gap sandwiched between the inclined wall surface on the inner peripheral side and the decompression wall 33, and a small amount of the rich air-fuel mixture from the auxiliary flame hole 31a and a small amount from the air port 43 of the large-diameter cylindrical portion 41 The auxiliary flame 32a is formed by the air. Thus, the flame stability of the primary flame 32 formed on the flame hole surface 3 is ensured.

  Further, the second gas discharge part 5 is fixed to the small-diameter cylinder 51 similar to that of the first embodiment whose upstream side is connected to an off-gas supply pipe led out from the anode electrode of the fuel cell, and the tip (upper end) thereof. And a tip member 54. Then, off-gas is discharged as the second gas from the discharge ports 52, 52,... Penetrating through the tip member 54 toward the outer peripheral side and the diagonally upper side.

  Also in the second embodiment described above, the high WI city gas that is the first gas in the primary combustion chamber 23 can be primarily burned in the primary combustion chamber 23 in the state of the rich mixture, that is, with the second gas. Primary combustion can be performed in a low NOx emission state that avoids an excessively high combustion temperature without mixing with a certain off gas. Then, unburned unburned components can be completely burned by secondary combustion together with off-gas in the secondary combustion chamber 24 by the secondary air from the air ejection section 4. Thereby, reduction of NOx emission amount can be achieved. Moreover, during the secondary combustion, the off-gas can be burned simultaneously by diffusion combustion, and even if the off-gas is a low WI gas containing a large amount of hydrogen, there is no inconvenience such as the occurrence of flashback.

  Various configurations other than the example of FIG. 4 described above can be adopted as a configuration for ensuring flame stability on the flame hole surface. For example, the decompression wall 33 in FIG. 4 may be omitted as shown in FIG. 5A, and the flame hole surface 3 is projected in a square shape instead of a trapezoidal shape as shown in FIG. 5B. Further, as shown in FIG. 5C, pressure reducing walls 33 may be provided on both the inner and outer sides.

<Third Embodiment>
FIG. 6 shows a combustion apparatus according to the third embodiment. In the third embodiment, a cooling means 11 is provided for the ignition means 7 based on the second embodiment.

  That is, as shown in FIG. 7, a cut-and-raised portion 27 is provided on the inner peripheral side partition wall 21 a in the vicinity of the ignition means 7 on the combustion space 2 side, and the opening 28 opens toward the base portion 71 of the ignition means 7. To do. Air is blown from the annular gap 82 between the inner and outer partition walls 21a and 21b to the base 71 of the ignition means 7 through the opening 28.

  In the case of this third embodiment, the air blown from the opening 28 to the base 71 swirls along the inner peripheral surface of the inner peripheral partition wall 21a, and the swirling air flow causes the base 71 to move. A swirling air layer is formed. Thereby, the ignition means 7 can be cooled without disturbing the swirling air layer for cooling the secondary flame 45 (see FIG. 1), that is, without adversely affecting the combustion state of the secondary flame 45. become able to. As a result, it is possible to maintain or improve the thermal durability of the protective glass of the spark plug constituting the ignition means 7. Further, by forming the swirling air layer, not only the ignition means 7 but also the secondary flame 45 and the inner peripheral partition wall 21a are blocked so that the inner peripheral partition wall 21a does not become excessively hot. Can be cooled. In addition, for example, compared with the case where cooling is performed by blowing air from the base of the ignition means 7 toward the radially inner side, the amount of cooling air to be blown, that is, the amount of blowing air that does not contribute to combustion can be reduced. Become.

  The above-mentioned cut-and-raised portion 27 may be bent or semi-circular or elliptical as shown in FIG. 6, bent or trapezoidal or square-shaped, or may be cut inward on three sides. Either cut or raised may be used.

<Fourth embodiment>
FIG. 8 shows a combustion apparatus according to the fourth embodiment. The fourth embodiment is based on the second embodiment, and is provided with a cooling means 13 for the flame detection means 12 constituted by a sheath thermocouple or the like.

  That is, the flame detection means 12 is projected to the center position through the partition walls 21a and 21b at the downstream end side position (position near the exhaust port 29) of the secondary combustion chamber 24. A cooling air layer for cooling is formed by the cooling means 13 at the upstream side position. The cooling means 13 for forming such a swirling air layer is composed of swirling blades provided in the circumferential direction of the inner peripheral side partition wall 21a, and the air supplied from the annular gap 82 on the outer peripheral side of the swirling blades While passing, the blowing direction to the secondary combustion chamber 24 is converted into a direction of turning along the inner peripheral surface of the partition wall 21a.

  In the case of the fourth embodiment, the air flowing into the swirl vanes of the cooling means 13 from the annular gap 82 blows out in the secondary combustion chamber 24 as a circumferential flow along the inner peripheral surface of the partition wall 21a. Will be. As a result, a swirling air layer is formed in a region including the base 121 of the flame detecting means 12, and the swirling air layer does not disturb the secondary flame 45 or the off-gas flame 53 (see FIG. 1), and the flame detecting means 12 Can be cooled. In particular, the off-gas flame 53 may be a high-capacity flame 53a (see FIG. 8) in which off-gas is discharged at a large flow rate or a small-capacity flame 53b in which a low flow rate is discharged. It is possible to reliably cool the flame detection means 12 without adversely affecting the flame, and to reliably perform flame detection while maintaining its thermal durability.

<Other embodiments>
As shown in FIG. 9 (a) or 9 (b), the flame hole surface 14 is disposed at a central position (position closer to the inside) in the combustion space 2a, and the air ejection portion 15 is located more than the flame hole surface 14. It is arranged on the outer peripheral side (position closer to the outer side) and downstream (upper side) of the combustion space 2a, and the second gas discharge part 16 is arranged on the outer peripheral side of the air ejection part 15 and further downstream. Also good. In order to do this, for example, the combustion space 2a may be formed by partition walls 17, 18, and 19 that are triple cylinders in the inner and outer circumferential directions separated from each other. Then, an outlet 151 for blowing secondary air from the air blowing portion 15 and an outlet 161 for blowing the second gas from the second gas discharging portion 16 are opened so as to intersect with each other as shown in FIG. Or may be opened to the same inner peripheral side as shown in FIG. 9B.

It is a section explanatory view showing the combustion device of a 1st embodiment of the present invention. It is a longitudinal cross-sectional explanatory drawing which shows the combustion apparatus of 2nd Embodiment. FIG. 3 is a cross-sectional explanatory view taken along line AA in FIG. 2. It is an expanded sectional explanatory view showing an example of a flame hole surface. FIG. 5A, FIG. 5B, and FIG. 5C are cross-sectional explanatory views showing other configuration examples of the flame surface. It is a fragmentary perspective view which shows 3rd Embodiment. It is an expanded sectional explanatory view in the BB line of FIG. It is a fragmentary end view which shows 4th Embodiment. FIG. 9A is a partial perspective view showing another embodiment, and FIG. 9A shows a case where secondary air and the second gas are blown in a crossing direction. FIG. 9B shows a case where the secondary air and the second gas are blown out. The case where it blows in the same direction is shown.

Explanation of symbols

2, 2a Combustion space 3 Flame surface 4, 15 Air ejection part 5, 16 Second gas discharge part 6 Guiding wall 7 Ignition means 11, 13 Cooling means 12 Flame detection means 24 Secondary combustion chamber (secondary combustion zone)
71 Base of ignition means 121 Base of flame detection means

Claims (7)

The fuel gas supplied from the fuel gas supply system is a first gas having a high Wobbe index, and the hydrogen-containing gas generated in the fuel cell is a second gas having a low Wobbe index. A combustion device for burning in a combustion space ,
An upstream primary combustion chamber communicating with each other in the upstream and downstream directions of the combustion space, and a downstream secondary combustion chamber,
A burner port surface to form a primary flame air concentration higher first gas concentration lower than the theoretical combustion air amount rich mixture is incomplete combustion flame is supplied to the primary combustion chamber above,
An air ejection section for blowing secondary air to the combustion gas generated from the primary flame in the secondary combustion chamber at a position downstream of the primary flame formed on the flame hole surface ;
Open downstream position than the air ejecting part, towards the unburned components secondary combustion is Ru above two Tsugi燃combustion chamber contained in the combustion gas by balloon secondary air from the air ejection unit e Bei a second gas discharging part that discharges said second gas,
In the secondary combustion chamber, the unburned component is subjected to secondary combustion, and at the same time, the second gas discharged from the second gas discharge portion is diffusely burned to form a secondary flame. Combustion device characterized by that. The combustion device according to claim 1 ,
The flame hole surface is disposed at a position closer to the outside in the combustion space, the air ejection portion is disposed at a position closer to the inner side than the flame hole surface, and the second gas discharge portion is disposed from the air ejection portion. Is also disposed so as to open to a downstream position. The combustion apparatus according to claim 2 , wherein
An induction wall that projects from the position downstream of the flame hole surface toward the combustion space so as to face the flame hole surface and guides the flow of combustion gas from the primary flame to the air ejection part side. The combustion apparatus further comprising. The combustion apparatus according to claim 2 or claim 3 ,
A combustion apparatus in which the direction of the opening is set so that the second gas from the second gas discharge section is discharged in a direction intersecting the upstream and downstream directions of the combustion space. The combustion apparatus according to claim 1 , wherein
Ignition means disposed so as to project into the combustion space from the partition wall that defines the combustion space, and cooling means for cooling the ignition means,
The combustion device is configured such that the cooling means blows cooling air toward a base located near the partition wall of the ignition means. The combustion apparatus according to claim 1 , wherein
Flame detecting means disposed so as to project into the combustion space from a partition wall that defines the combustion space; and cooling means for cooling the flame detecting means,
The combustion device, wherein the cooling means is configured to blow cooling air toward a base located near the partition wall of the flame detection means. The combustion apparatus according to claim 5 or 6 ,
The said cooling means is a combustion apparatus comprised so that cooling air may be blown off along the inner peripheral surface of a division wall from the division wall inner surface position.

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