JP3702460B2 - Multistage combustion equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a rich burner for ejecting a rich mixture with a high fuel concentration is arranged so as to form a rich flame in multiple stages from the upstream to the downstream of the combustion space, and a lean mixture with a low fuel concentration is formed in the combustion space. The present invention relates to a multi-stage combustion apparatus that employs a concentration combustion system that jets and burns.
[0002]
[Prior art]
As this type of multistage combustion apparatus, one illustrated in FIG. 8 is known. In this case, for example, a cylindrical thick burner 102 is disposed at the center of a cylindrical housing 101 to form a donut cylindrical combustion space 103, and an upstream end side (the upper end of FIG. The heating object (for example, heat exchanger) 104 heated by the combustion heat is disposed on the side. The rich burner 102 discharges the rich air-fuel mixture from the inner surface on the inner peripheral side of the combustion space 103 toward the outer peripheral side so that the rich flames 105, 105,. It is configured to be formed in multiple stages (upper side in the figure). And the light burner 106 is arrange | positioned in the downstream end side (lower end side of the same figure) of the combustion space 103, and a lean air-fuel mixture is ejected toward the downstream side of the combustion space 103 from this light burner 106, The above-mentioned The lean air-fuel mixture is burned in the combustion space 103 heated by the rich flames 105, 105,.
[0003]
[Problems to be solved by the invention]
However, in the above-described multistage combustion apparatus, the lean air-fuel mixture is ejected from the upstream end side to the downstream side of the combustion space 103, while the rich air-fuel mixture is discharged from the upstream side to the downstream side of the combustion space 103. Because the rich flames 105, 105,... Are formed in multiple stages, the combustion reaction of the lean air-fuel mixture proceeds toward the downstream side of the combustion space, and the volume of the combustion gas decreases downstream of the combustion space 103 due to thermal expansion accompanying the combustion. Increases as you go. However, since the cross-sectional area in the cross section of the combustion space 103 from the upstream side to the downstream side is substantially constant, the internal pressure increases as it goes downstream of the combustion space, and the cross-sectional flow velocity of the combustion gas becomes higher. For this reason, the combustion noise increases as the spatial combustion load of the combustion space 103 increases, and the incombustible component tends to increase as the residence time of the combustion gas in the combustion space 103 decreases. become.
[0004]
The present invention has been made in view of such circumstances, and the object of the present invention is to control an increase in the spatial combustion load so as to suppress an increase in combustion noise and an increase in unburned components. An object of the present invention is to provide a multistage combustion apparatus that can be suppressed as much as possible.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a rich mixture having a high fuel concentration and a lean mixture having a low fuel concentration are separately and simultaneously injected into the combustion chamber. While the dense burner is configured to burn and burn, the rich burner that jets and burns the rich mixture is disposed so as to form a rich flame in multiple stages from upstream to downstream with respect to the combustion space of the combustion chamber, A multistage in which the light burner for injecting the lean air-fuel mixture is disposed upstream of the combustion space so as to inject the lean air-fuel mixture in a direction crossing the direction in which the rich flame formed by the rich burner extends. The following specific items were provided for the combustion device. That is, the combustion chamber is formed so that the cross-sectional area of the combustion space expands continuously or stepwise from upstream to downstream, and the lean mixing from the light burner is performed by heating with the rich flame of each rich burner. While the gas is burned, the rich flame is completely burned by the excess air of the lean air-fuel mixture (Claim 1).
[0006]
According to the first aspect, the lean air-fuel mixture ejected from the light burner is heated in contact with the rich flame as it goes downstream of the combustion space, and the combustion reaction proceeds. As the combustion reaction proceeds, the combustion gas Even if the gas expands thermally, the combustion space is formed to expand from upstream to downstream, so the increase in the cross-sectional flow velocity of the combustion gas is suppressed, which increases combustion noise and increases unburned components. Will be suppressed. In other words, it is possible to suppress an increase in combustion noise and an increase in unburned components accompanying an increase in the cross-sectional flow velocity of the combustion gas by controlling so as to suppress an increase in spatial combustion load. In addition, the degree of suppression of the increase in the cross-sectional flow velocity of these combustion gases can be controlled to a predetermined value by adjusting the degree of expansion of the combustion space. In addition, while the lean mixture is burned by heating with the rich flame, the rich flame is completely burned by the excess air of the lean mixture, so that the excess air ratio is an extremely lean mixture near the flammability limit. Even if it is possible to burn stably, this makes it possible to achieve a high TDR (turn-down ratio; the ratio between the minimum and maximum values of the mass flow rate of the fuel, which appears as a wide combustion range) and low NOx Combustion can be realized.
[0007]
As a configuration that further embodies the above invention, the combustion space is partitioned and formed in a conical shape whose cross-sectional area increases from the upstream side toward the downstream side, and the rich burner is moved from the outer peripheral surface of the combustion space to the inner flame side. It can also arrange | position so that it may form toward (claim 2).
Alternatively, as the combustion space, the inner surface on the outer peripheral side is partitioned by the cylindrical peripheral surface, while the inner surface on the inner peripheral side is partitioned by the outer peripheral surface of the thick burner disposed at the center position, and the thick burner is It is also possible to adopt a configuration in which the cross-sectional area is reduced in the conical shape from the downstream side toward the downstream side, and the rich flame is formed toward the outer peripheral side.
[0008]
With respect to the rich flame forming portion of the rich burner according to claim 2 or 3, the flame holding plate for protecting the rich flame from the flow of the lean air-fuel mixture protrudes from the upstream side of the rich flame. (Claim 4). In this case, since the base of the rich flame is protected by the flame holding plate, even if the jet speed of the lean air-fuel mixture is high, the rich flame does not become unstable due to the flow of the lean air-fuel mixture. A flame is formed, and the combustion reaction of the lean air-fuel mixture can proceed more reliably.
[0009]
Further, the rich burner according to claim 2 or claim 3 may be formed such that the rich flame forming portion is stepped from the upstream side toward the downstream side (claim 5). In this case, since the base of the rich flame is protected by each stepped step, the rich flame can be stably formed and diluted without adding the flame holding plate of claim 4 above. It becomes possible to advance the combustion reaction of gas more reliably.
[0010]
The rich burner according to any one of claims 1 to 5 is preferably formed at a position where the rich flames of each stage on both the upstream and downstream sides do not interfere with each other (claim 6). In this case, the contact area of the lean air-fuel mixture with each rich flame, which is arranged in multiple stages, increases, so that the lean air-fuel mixture and the rich air-fuel mixture can be completely burned more reliably, reducing the amount of NOx generated and Suppression of the generation of fuel components will be achieved.
[0011]
Further, a flow control plate for directing the flow of the lean air-fuel mixture toward the rich flame side of the rich burner may be provided on the inner surface of the combustion space of any of the above claims 1 to 6. 7). In this case, when the rich burner is provided on one side across the combustion space, the lean air-fuel mixture injected into the combustion space is more positively provided by providing the flow control plate at the other side position. It becomes possible to make it contact with a rich flame, and it becomes possible to accelerate the progress of the combustion reaction of the lean mixture.
[0012]
【The invention's effect】
As described above, according to the multistage combustion apparatus of claim 1, the combustion space is formed so as to expand from the upstream to the downstream, so that the combustion gas is generated as the combustion reaction of the lean air-fuel mixture progresses. Even if thermal expansion occurs, an increase in the cross-sectional flow velocity of the combustion gas can be suppressed, and thereby an increase in combustion noise and an increase in unburned components can be suppressed. In addition, the degree of suppression of increase in the cross-sectional flow velocity of these combustion gases can be controlled to a predetermined value by adjusting the degree of expansion of the combustion space. Further, since the lean air-fuel mixture can be burned completely, high TDR and low NOx combustion can be realized.
[0013]
According to claim 2 or claim 3, the combustion space of claim 1 can be specified more specifically, and the effect of claim 1 can be obtained more specifically.
[0014]
According to claim 4, the base of the rich flame can be protected by the flame holding plate in claim 2 or claim 3 without destabilizing the rich flame by the flow of the jetted lean mixture, By forming a stable rich flame, the combustion reaction of the lean air-fuel mixture can proceed more reliably.
[0015]
According to claim 5, by forming the rich burner in a stepped manner in claim 2 or claim 3, the base of the rich flame can be protected without providing the flame-holding plate as in claim 4. As described above, the stable formation of the rich flame enables the combustion reaction of the lean air-fuel mixture to proceed more reliably.
[0016]
According to claim 6, in any one of claims 1 to 5, the contact area of the lean mixture with respect to each of the rich flames arranged in multiple stages can be increased. Complete combustion can be achieved more reliably.
[0017]
According to claim 7, in any one of claims 1 to 6, by providing the flow control plate, the lean air-fuel mixture injected into the combustion space can be more positively brought into contact with the rich flame. And the progress of the combustion reaction of the lean air-fuel mixture can be further promoted.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
<First Embodiment>
FIG. 1 shows a multistage combustion apparatus according to a first embodiment of the present invention, in which 2 is a housing having an inner cylinder 21 and an outer cylinder 22 and is configured in a double cylinder shape, and 3 is a central axis X of the housing 2. A thick burner 4 is disposed along the donut cylindrical combustion chamber 4 defined between the dark burner 3 and the inner cylinder 21 of the housing 2, and 5 is a downstream end side of the combustion chamber (see FIG. 6 is a light burner disposed on the upstream end side (lower end side in the figure) of the combustion chamber 4.
[0020]
A cooling water chamber 7 that uses water as a cooling medium is defined between both the inner and outer cylinders 21 and 22 of the housing 2, and the cooling water chamber 7 is an outer peripheral wall of the combustion chamber 4 by water supplied from an inlet 7 a. Is cooled, and water preheated by heat exchange with the inner cylinder 21 heated by the combustion heat is supplied to the heat exchanger 5 from the outlet 7b. Further, inside the rich burner 3, the cooling water pipe 8 is disposed in contact with the inner surface of the wall constituting the rich flame forming portion 31, and the rich flame is formed by the cooling water passed through the cooling water pipe 8. The part 31 is cooled.
[0021]
The rich burner 3 is formed in a conical shape having a predetermined inclination angle α such that the cross-sectional area gradually decreases from the upstream side to the downstream side of the combustion chamber 4. The space 41 is formed so that its cross-sectional area gradually increases from the upstream side toward the downstream side at a predetermined change rate (a spread angle corresponding to the inclination angle α). The rich burner 3 has a gas chamber 32 to which a rich mixture is supplied, and a rich flame forming portion 31 is set on the outer peripheral surface. In the rich flame forming portion 31, a plurality of flame holes 33, 33,... Are arranged in multiple stages (at least two stages; FIG. 1 shows an example of seven stages) from the upstream side to the downstream side of the combustion chamber 4. Is set. That is, in the rich flame forming portion 31, a flame hole forming position is set for each stage at a predetermined interval from the upstream side to the downstream side of the combustion chamber 4, and the central axis X is set for each flame hole forming position. A large number of flame holes 33, 33,... Are formed in the radial direction as the center. As a result, the rich burner 3 discharges the rich air-fuel mixture R supplied to the gas chamber 32 from each flame hole 33 and forms the rich flame 9 in multiple stages from the upstream side to the downstream side with respect to the combustion space 4. It has become. In addition, a flame holding plate 34 is formed to protrude from the outer peripheral surface of the rich flame forming portion 31 at the lower position of each flame hole 33 (upstream position of the combustion space 4). The base is protected and stabilized so as not to be disturbed by the lean air-fuel mixture L ejected from the light burner 6. It should be noted that the flame holes 31 of each stage adjacent to each other in the upstream / downstream direction are positioned so as to prevent the rich flames 9 and 9 from interfering with each other in the upstream / downstream direction. As a result, the lean air-fuel mixture L and the rich flames 9 can reliably contact each other.
[0022]
The light burner 6 is disposed on the upstream end face (lower end face in FIG. 1) of the combustion chamber 4 so that a large number of injection holes 61, 61,. The light burner 6 is configured such that the lean air-fuel mixture L supplied to the donut-shaped gas chamber 62 is ejected upward from each nozzle hole 61 toward the combustion space 41 at a predetermined ejection speed.
[0023]
The rich air-fuel mixture R supplied to the gas chamber 32 of the rich burner 3 and the lean air-fuel mixture L supplied to the gas chamber 62 of the light burner 6 are composed of fuel gas (for example, propane) and air as a predetermined fuel. A rich mixture R that is premixed at a concentration and has an excess air ratio of less than 1 and one or more lean mixtures L are generated. The fuel mixture of the rich mixture R and the lean mixture L may be a gaseous fuel such as propane or a liquid fuel such as petroleum. In the case of liquid fuel, it may be premixed with air after vaporization. The lean air-fuel mixture L is supplied to the gas chamber 62 at a predetermined supply pressure (flow rate) and ejected from each nozzle hole 61 at an ejection speed faster than the combustion speed of the lean air-fuel mixture L. . That is, the deep flames formed by the lean air-fuel mixture L are not formed at the positions of the respective nozzle holes 61, that is, the fresh flames are ejected toward the combustion space 41 without being held, and are formed in multiple stages in the combustion space 41. The jetting speed is set such that the combustion reaction occurs sequentially by heating by the flames 9, 9,. In order to realize such an ejection speed, a combustion speed is assumed in accordance with the excess air ratio of the lean mixture, and a predetermined ejection speed (for example, several to several tens of times the combustion speed) based on this combustion speed. And the supply pressure (pressure and flow rate) of the lean air-fuel mixture L may be controlled so as to achieve the set ejection speed.
[0024]
In the above multistage combustion apparatus, a lean mixture is formed from the upstream end side of the combustion space 41 in a state where the rich flames 9, 9,... Are formed in multiple stages from the upstream side to the downstream side of the combustion space 41 toward the outer peripheral side. L is ejected toward the downstream at the predetermined ejection speed. That is, the lean air-fuel mixture L is ejected in a direction that intersects substantially perpendicularly to the direction in which each rich flame 9 extends. Then, the ejected lean mixture L does not form a flame at the position of each nozzle hole 61, and is heated in contact with the rich flame 9 as it goes downstream. In the combustion space 41, the lean air-fuel mixture L and the rich air-fuel mixture R both complete combustion and are completely combusted. In other words, the lean mixture L from the light burner 6 is burned by heating with the rich flames 9, 9,..., While the rich flames 9, 9,. It will be. For this reason, even an ultra-lean mixture near the flammability limit where the excess air ratio is near 2.0 can be stably burned, and as a result, an extremely high TDR (for example, 1:10 or more) And low NOx combustion (for example, 30 ppm or less; O ₂ = 0% conversion) can be realized. And combustion gas flows in into the said heat exchanger 5, and the heat exchanger 5 is heated with the combustion heat.
[0025]
When the combustion reaction proceeds, the sectional area of the combustion space 41 increases as the combustion space 41 moves downstream. Therefore, even if the combustion reaction progresses, the sectional flow velocity of the combustion gas increases. Thus, an increase in combustion noise and an increase in unburned components can be suppressed. That is, by adjusting the degree of expansion toward the downstream side of the combustion space 41, the cross-sectional flow velocity of the combustion gas is made constant from the upstream to the downstream, or the downstream cross-section is compared with the flow velocity of the upstream cross-section. It is possible to control such that the flow rate is controlled within a predetermined range of increase or decrease.
[0026]
In such a control, an example of the relationship between the cross-sectional flow velocity of the combustion gas and the expansion angle (corresponding to the inclination angle α of the concentrated burner 3 in this embodiment) β of the combustion gas is shown as the cross-sectional flow velocity of the combustion gas. When the flow velocity of the most upstream cross section is V and the flow velocity of the most downstream cross section is Vo, β = 55 degrees to 5 degrees may be set to make Vo = (V / 2) to 3V. That is, as the expansion angle β of the combustion space 41 is increased, the ratio of the most downstream cross-sectional flow velocity Vo to the most upstream cross-sectional flow velocity V can be reduced, and by setting a predetermined expansion angle β, the most upstream cross-section. The flow velocity V and the most downstream cross-sectional flow velocity Vo can be made equal. If the expansion angle β of the combustion space 41 is too small, the most downstream cross-sectional flow velocity Vo becomes considerably faster than the most upstream cross-sectional flow velocity V. However, even in this case, the increase in the cross-sectional flow velocity of the combustion gas can be suppressed as compared with the conventional case where the cross-sectional area of the combustion space is substantially constant from upstream to downstream (see FIG. 8). The above effect can be obtained by the amount of increase suppression.
[0027]
When the combustion reaction proceeds, the inner cylinder 21 of the housing 2 that defines the combustion space 41 and the rich flame forming portion 31 of the rich burner 3 are both cooled by the cooling water and contacted with these. Since the combustion flame is cooled, low NOx combustion is also realized.
[0028]
Second Embodiment
FIG. 2 shows a multistage combustion apparatus according to a second embodiment of the present invention. This second embodiment is different from the first embodiment only in that a thick burner 3a having a thick flame forming portion 31a formed in a step shape is used, and the other components are the same as those of the first embodiment.
For this reason, the same code | symbol as 1st Embodiment is attached | subjected to the same component as 1st Embodiment, and detailed description is abbreviate | omitted.
[0029]
The rich burner 3a is formed as a stack of cylinders whose outer diameters decrease step by step from the upstream end side (lower end side in FIG. 2) to the downstream end side (upper end side in FIG. 2) of the combustion space 41. It is a thing. And the said rich flame formation part 31a forms the flame hole 33,33, ... from which the rich air-fuel mixture R is discharged in the root position for every level | step difference in which the said outer diameter changes. As described above, by setting the positions of the respective flame holes 33 at the base positions of the respective steps as described above, the base portions of the rich flames formed in the respective flame holes 33 are protected. Therefore, the flame holding plate in the first embodiment is protected. 34 (see FIG. 1) can be omitted.
[0030]
Note that the expansion angle β of the combustion space 41 in the second embodiment is determined by the average inclination angle of the rich flame forming portion 31a.
[0031]
According to the second embodiment, the same operation and effect as the first embodiment can be obtained.
[0032]
<Third Embodiment>
FIG. 3 shows a multistage combustion apparatus according to a third embodiment of the present invention. In the third embodiment, only the flow control plates 10, 10,... That direct the flow of the lean air-fuel mixture L toward the rich flames 9, 9,. Unlike the second embodiment, the other components are the same as those of the first and second embodiments. For this reason, the same code | symbol as 1st and 2nd embodiment is attached | subjected to the same component as 1st and 2nd embodiment, and detailed description is abbreviate | omitted.
[0033]
The flow control plates 10, 10,... Are constituted by donut annular plates having different inner diameters, and the outer peripheral portions thereof are fixed to the inner peripheral surface of the inner cylinder 21 of the housing 2. Each flow control plate 10 changes the flow of the lean air-fuel mixture L rising along the inner peripheral surface of the inner cylinder 21 so as to flow toward the rich flames 9, 9,. The positions are set corresponding to the rich flames 9, 9,. Further, the inner diameter of the flow control plates 10, 10,... Is such that the donut-shaped opening area between each inner peripheral surface and the outer peripheral surface of the rich flame forming portion 31a on the same horizontal plane is directed from the upstream side to the downstream side. Are set to increase in order.
[0034]
In the case of the third embodiment, in addition to the actions and effects of the first and second embodiments, the lean mixture L ejected from the light burner 6 is on the side away from the rich burner 3a of the combustion space 41. The lean mixture L rising along the inner peripheral surface of the inner cylinder 21 can be controlled to flow toward the rich flames 9, 9,..., And the lean mixture L can be controlled with the rich flames 9, 9,. The combustion reaction of the lean air-fuel mixture L can be promoted by positive contact.
[0035]
Note that the flow control plate 10 is not configured by a donut annular plate as described above, but may be configured by an arc-shaped plate and fixed to a part of the inner cylinder 21 in the circumferential direction. . Even in this case, the flow of the lean air-fuel mixture L can be changed from the inner peripheral surface side of the inner cylinder 21 to the rich flames 9, 9,. Further, the flow control plate 10 of the third embodiment may be added to the first embodiment.
[0036]
<Fourth embodiment>
FIG. 4 shows a multistage combustion apparatus according to a fourth embodiment of the present invention. In the fourth embodiment, a second light burner 11 is further added to the third embodiment, and the other points are the same as those in the third embodiment. For this reason, the same code | symbol as 3rd Embodiment is attached | subjected to the same component as 3rd Embodiment, and detailed description is abbreviate | omitted.
[0037]
The second light burner 11 is configured in a donut cylindrical shape and is disposed at a position on the inner peripheral surface side of the inner cylinder 21. The second light burner 11 has a gas chamber 112 defined behind the inner peripheral wall 111, and nozzle holes 113, 113,... For ejecting a lean air-fuel mixture L toward the combustion space 41 with respect to the inner peripheral wall 111. Is formed. The position of each nozzle hole 113 is set to a position immediately above each flow control plate 10 so that the lean air-fuel mixture L is ejected toward the inner peripheral side. The gas chamber 112 is supplied with the lean air-fuel mixture L at a predetermined supply pressure at the same time as the gas chamber 62 of the first light burner 6 or by selecting one of them by switching the valve, for example. Yes.
[0038]
In the case of the fourth embodiment, in addition to the same operations and effects as those of the third embodiment, the following operations and effects can be obtained. For example, at first, the lean mixture L is jetted only from the first light burner 6 to perform the combustion operation, and in the middle, the lean mixture L is also discharged from the second light burner 11 according to the combustion state (temperature rise, etc.). The range in which the lean air-fuel mixture L is ejected to the combustion space 41 is changed and adjusted such that the air is ejected or the lean air-fuel mixture L is ejected from the first and second light burners 6 and 11 from the beginning. Will be able to.
[0039]
<Other embodiments>
In addition, this invention is not limited to the said 1st-4th embodiment, Various other embodiments are included. That is, in the said 1st-4th embodiment, although the cross-sectional shape of the housings 2 and 2a was made circular and the combustion space 41 was comprised in the annular | circular shape, the cross-sectional shape of combustion space itself is not restricted to an annular | circular shape. Various other shapes may be employed. For example, a rectangular, triangular, or polygonal shape may be employed as the cross-sectional shape of the combustion space.
[0040]
In the first to fourth embodiments, the lean air-fuel mixture L is ejected upward (downstream of the combustion space) from each nozzle hole 61 of the light burner 6. The lean air-fuel mixture L may be ejected as a swirling flow into the combustion space 41 by inclining a predetermined amount in the direction.
[0041]
In the first to fourth embodiments described above, the downstream side of the combustion space 41 is up and the upstream side is down. However, the multistage combustion apparatus is arranged so that the upstream and downstream directions of the combustion space 41 are lateral. May be used.
[0042]
In the first to fourth embodiments, the thick burners 3 and 3a are arranged at the center side position (inner circumference side position) of the combustion space 41, but conversely arranged at the outer circumference side position of the combustion space. You may make it do. As such an example, the following various forms can be adopted.
[0043]
First, as shown in FIG. 5, the housing 2b is formed in a trumpet shape that extends from the upstream end side where the light burner 6a is disposed toward the downstream side (upward side in the figure). The rich burner 3b is constituted by the rich mixture supply pipe 31b arranged spirally along the peripheral surface. The rich mixture supply pipe 31b constitutes a rich flame forming part. Then, the flame holes 33b are opened obliquely upward (obliquely downstream) at predetermined intervals with respect to the rich mixture supply pipe 31b so that the rich flames 9, 9,. It is formed obliquely upward. In this case, the lean air-fuel mixture L ejected from the light burner 6a is heated by the respective rich flames 9, and the combustion reaction proceeds in sequence and burns in the region indicated by reference numeral 42 in FIG. Further, since each flame hole 33b is opened obliquely upward, it becomes difficult to be influenced by the flow of the lean air-fuel mixture L ejected upward (downstream of the combustion space), and the rich flames 9, 9 The flame holding performance can be improved. Further, since the rich mixture supply pipe 31b located on the outer peripheral side of the combustion space 41 is spirally arranged toward the downstream side of the combustion space, the lean air-fuel mixture L that flows along the outer peripheral side of the combustion space 41 is disposed. Can be obtained the same effect as a flow control plate (see, for example, reference numeral 10 in FIG. 3) that guides to the rich flames 9, 9,. Note that the rich air mixture R may be supplied from both the upstream side (the lower side in the drawing) and the downstream side (the upper side in the drawing) with respect to the rich air mixture supply pipe 31b, or the rich air mixture supply pipe 31b. On the other hand, the rich air-fuel mixture R may be supplied from the upstream side (lower side of the drawing) and the downstream side (upper side of the drawing) may be closed. In this case, what is necessary is just to set so that the hole diameter of the flame hole 33b may become small as it goes downstream.
[0044]
Secondly, as shown in FIG. 6, in a cylindrical housing 2 c, it expands in a trumpet shape from the upstream end side where the light burner 6 a is disposed toward the downstream side (upper side in the figure). A concentrated mixture supply pipe 31c wound in a spiral shape and in close contact with each other is disposed. The concentrated mixture supply pipe 31c constitutes the concentrated burner 3c, and at the same time forms a combustion space 41. In addition, the rich flame formation part is comprised by this rich mixture supply pipe 31c. .. Are then opened obliquely upward (diagonally downstream) at predetermined intervals in the same manner as described above, so that the rich flames 9, 9,... Are formed obliquely upward from the multi-stage position. As a result, the lean air-fuel mixture L ejected from the light burner 6 a is heated by each rich flame 9, and the combustion reaction proceeds in sequence to be burned in the region 42 along the central axis of the combustion space 41. Note that each flame hole 33c is opened obliquely upward, and a rich mixture supply pipe 31c located on the outer peripheral side of the combustion space 41 is disposed spirally toward the downstream side of the combustion space. The actions and effects of the points are the same as described above.
[0045]
Third, as shown in FIG. 7 (a), the dark burner 3d itself is formed in a trumpet shape that extends from the upstream end side where the light burner 6a is disposed toward the downstream side (upward side in the figure), The combustion chamber 4 may be partitioned by the thick burner 3d. Then, the rich air-fuel mixture R is discharged toward the inner peripheral side (center axis side) of the combustion space 41 to form a rich flame.
[0046]
Fourthly, as shown in FIG. 7B, the thick burner 3e is formed in a cylindrical shape, but a conical member 12 is disposed therein, and the combustion chamber 4 is defined by the thick burner 3e and the conical member 12. You may make it form division. A rich mixture R is discharged from the inner peripheral surface of the rich burner 3e toward the conical member 12 to form a rich flame, while lean mixing is performed upward from the periphery of the lower end of the conical member 12 toward the combustion space 41. Qi L is ejected.
[Brief description of the drawings]
FIG. 1 is an explanatory cross-sectional view showing a first embodiment of the present invention.
FIG. 2 is a view corresponding to FIG. 1 showing a second embodiment.
FIG. 3 is a view corresponding to FIG. 1 showing a third embodiment.
FIG. 4 is a view corresponding to FIG. 1 showing a fourth embodiment.
FIG. 5 is an explanatory cross-sectional view showing another embodiment.
6 is a view corresponding to FIG. 5 showing another embodiment other than FIG.
7 is a cross-sectional explanatory view showing another embodiment other than FIGS. 5 and 6. FIG. 7 (a) adopts a trumpet-like dark burner, and FIG. 7 (b) adopts a cylindrical thick burner. Each case is shown.
FIG. 8 is a view corresponding to FIG. 1 showing a conventional multistage combustion apparatus.
[Explanation of symbols]
3,3a-3e dark burner
4 Combustion chamber
6,6a, 11 Light burner
9 Deep flame
10 Flow control board
31, 31a Rich flame formation part
31b, 31c Rich mixture supply pipe (rich flame formation part)
33 Flame of rich mixture
34 Flame holding plate
41 Combustion space
61 Hole of lean mixture
L Dilute mixture
R Rich mixture

Claims (7)

A fuel-air mixture, a rich mixture having a high fuel concentration and a lean mixture having a low fuel concentration, are individually and simultaneously ejected toward the combustion chamber and burned to burn the light and dark combustion system. A rich burner that injects and burns an air-fuel mixture is arranged so as to form a rich flame in multiple stages from upstream to downstream in the combustion space of the combustion chamber, while a light burner that injects the lean air-fuel mixture is diluted A multi-stage combustion apparatus disposed at an upstream position of the combustion space so as to eject gas in a direction intersecting a direction in which the rich flame formed by the rich burner extends,
The combustion chamber is formed so that the cross-sectional area of the combustion space expands continuously or stepwise as it goes from upstream to downstream,
The multi-stage is configured to burn the lean mixture from the light burner by heating with the rich flame of each rich burner, while completely burning the rich flame with the excess air of the lean mixture Combustion device. The multi-stage combustion apparatus according to claim 1,
The combustion space is partitioned and formed in a conical shape whose cross-sectional area increases from the upstream side toward the downstream side, and the rich burner is disposed so as to form the rich flame from the outer peripheral surface of the combustion space toward the inner peripheral side. Multistage combustion device. The multi-stage combustion apparatus according to claim 1,
In the combustion space, the inner surface on the outer peripheral side is partitioned by the cylindrical peripheral surface, while the inner surface on the inner peripheral side is partitioned by the outer peripheral surface of the dark burner disposed at the center position,
The multi-stage combustion apparatus, wherein the rich burner is formed in a conical shape with a cross-sectional area decreasing from the upstream side toward the downstream side, and is configured to form the rich flame toward the outer peripheral side. A multistage combustion apparatus according to claim 2 or claim 3, wherein
A multi-stage combustion apparatus in which a flame holding plate for protecting the rich flame from the flow of the lean air-fuel mixture protrudes from the rich flame forming portion of the rich burner at a position upstream of the rich flame. A multistage combustion apparatus according to claim 2 or claim 3, wherein
The rich burner is a multistage combustion apparatus in which the rich flame forming portion is formed in a stepped shape from the upstream side toward the downstream side. A multi-stage combustion apparatus according to any one of claims 1 to 5,
The rich burner is a multi-stage combustion apparatus configured so that the rich flames at each stage on both the upstream and downstream sides are formed at positions where they do not interfere with each other. It is a multistage combustion apparatus in any one of Claims 1-6,
A multi-stage combustion apparatus provided with a flow control plate for directing the flow of a lean air-fuel mixture toward the rich flame side of the rich burner on the inner surface of the combustion space.

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