JP3320903B2 - Combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses the generation of harmful nitrogen oxides (NOx) by simultaneously burning an excess fuel mixture (rich mixture) and an excess air mixture (light mixture). It relates to a gray-scale combustion device.

[0002]

2. Description of the Related Art Conventionally, a gray-scale combustion apparatus has been known as one of combustion apparatuses for achieving low NOx. This device simultaneously ejects a rich mixture with a low air ratio (the ratio of the actual air amount to the theoretical air amount) from some of the multiple outlets, and a lean mixture with a high air ratio from the other outlets. And burn it. For example, in Japanese Patent Application Laid-Open No. 3-263501, as shown in FIG. 4 (a), a dense burner RB for ejecting a rich mixture and a light burner LB for ejecting a light mixture are alternately arranged in a line. A lean-burn apparatus for burning has been proposed. In this case, oxygen becomes insufficient at the base of the flame (hereinafter, referred to as “rich flame”) from the deep-side burner port RH of the deep-side burner RB. Exhaust gas (called a flame) causes oxygen deficiency and suppresses generation of NOx. On the other hand, in the light flame from the light side flame port LH, since the fuel gas is lean, the flame temperature is reduced and the generation of NOx is suppressed, and the total NOx is reduced by a synergistic effect of these.

[0003]

However, since it is necessary to provide the dark side burners and the light side burners independently and alternately, burners and nozzles are required twice as compared with a normal Bunsen type burner. However, there is a problem that the cost is approximately doubled. Further, Japanese Utility Model Laid-Open No. 2-115627 (shown in FIG. 4B) or Japanese Unexamined Patent Publication No. Hei 6-2819 (shown in FIG. 4C) remixes a part of the rich mixture with combustion air. An inexpensive structure for producing a lean mixture is proposed. (In the figure, the solid arrows indicate the flow of the fuel gas, and the broken arrows indicate the flow of the combustion air.) In these cases, there is an advantage that the light-side burner is not provided separately, so that it can be manufactured at low cost. In any case, there is a problem that the mixing property of the light mixture is poor. That is, structurally, the distance from the mixing start portion to the light-side flame port 56 in the light-mixed gas chamber 54, that is, the mixing distance, is short, so that the mixing is incompletely ejected from the light-side flame port 56. There was a problem. Therefore, if the mixture of the combustion gas and the combustion air of the lean mixture is uneven and the concentration is uneven, the combustion flame is liable to lift or flashback (flashback),
Flammability significantly deteriorates. In other words, a portion leaner than the predetermined concentration of the lean mixture becomes excessive in air, and the flame is easily lifted and burned. In addition, the rich portion has a higher burning speed, and is easily backfired and burnt. Accordingly, it is an object of the present invention to solve the above-mentioned problems, to provide a low-intensity combustion device which can be manufactured at a low cost, improves the mixing property of a lean air-fuel mixture, and has good combustibility.

[0004]

A combustion apparatus according to the present invention which solves the above-mentioned problems comprises a plurality of fuel gas and combustion air which are sucked and mixed to eject a rich air-fuel mixture having a low air ratio from a rich-side flame opening. The dense side burners are arranged side by side at intervals, and a light mixture having a higher air ratio than the rich mixture is ejected from between each of the adjacent dense side burners, so that the light side is next to the dense side flame opening. Forming a flame port, the light mixture flow path to the light side flame port mixes a part of the rich mixture of the rich side burner with the combustion air sent toward the light side flame port, In a combustion device having a lean mixture chamber for producing a lean mixture, a discharge hole for ejecting a part of the rich mixture from the rich burner to the lean mixture chamber is provided on an upper side surface of the rich burner. provided with, the ejection
The rich air-fuel mixture blown out of the outlet is drawn along the side of the above-mentioned rich burner.
Therefore, a gist of the present invention is to provide a guide plate for guiding the mixture up to the lower portion of the light mixture chamber . Further, the present invention according to claim 2
Ming's combustion device further uses the guide plate to
The rich mixture guided to the upstream of the air chamber faces the combustion air
The fact that an auxiliary plate has been provided to prevent collision
And

[0005]

[Action] combustion apparatus of the present invention having the above structure, discharging a portion of the dense mixture from a discharge hole provided in the upper side surface of the dark side burners, the guide plate The dark dense mixture ejected from the ejection hole ~ side
It is guided along the side of the burner to the lower upstream of the lean mixture chamber . That is, since the discharge hole is provided in the upper part of the side surface of the rich side burner, a sufficiently mixed rich mixture near the rich side flame outlet is guided to the light mixture chamber. The guide plate is so guides the rich mixture from the discharge hole to the upstream of a pale mixture chamber, downstream of the light-side flame hole mixing distance from the upstream of pale mixture chamber with dense mixture and the combustion air To secure enough. Therefore, a light mixture having a uniform concentration can be obtained.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the combustion apparatus of the present invention will be described below.

FIG. 1 shows a schematic configuration of a combustion apparatus as one embodiment. In the drawings, the solid arrows indicate the flow of the fuel gas, and the dashed arrows indicate the flow of the combustion air. Combustion device 1
Is configured such that a plurality of burner units 2 are arranged in a line, and combustion air is supplied from below. In the lower part of the burner unit 2, a throat 3 serving as a fuel gas inlet is formed in a lateral direction, and fuel gas is injected and supplied from a gas nozzle 42 provided on a gas nozzle table 40, and the combustion air (primary air) is accordingly supplied. ) Is sucked in (FIG. 2). The downstream side of the throat 3 is bent upward and connected to a mixing chamber 5 (hereinafter, referred to as a rich mixture chamber).
Is provided with a flame forming surface 24 on which a plurality of flames 7 (hereinafter referred to as dark side flames) are formed. Therefore, the fuel gas and the combustion air are mixed while passing through the throat 3 and the rich air-fuel mixture chamber 5, and the air-fuel mixture is ejected upward from the rich-side flame opening 7. The excess air ratio (the ratio of the primary air amount to the theoretical air amount of the gas) of this mixture is set low, and is set to 0.5 in this embodiment. Hereinafter, this mixture is referred to as a rich mixture.

As shown in FIG. 1, the respective burner units 2 are arranged in parallel in a burner case 11 at a predetermined interval and housed in a combustion chamber 12. A blower 13 (not shown) is provided below the combustion chamber 12 so as to supply combustion air into the combustion chamber 12. A rectifying plate 14 (for example, punching metal) is provided on the bottom surface of the burner case 11, and the combustion air passing through a plurality of holes formed in the rectifying plate has a uniform flow velocity, and the air flows between the burner units 2. It is designed to flow upward.

On the other hand, a plurality of mixture discharge ports 8 (hereinafter, referred to as discharge holes) are formed in a row in the upper part of the side surface of the rich mixture chamber 5 of the burner unit 2. This discharge hole 8 is provided at a position as close as possible to the dark side flame opening 7. Burner unit 2
A guide plate 9 for guiding a rich air-fuel mixture from the discharge hole 8 is provided at an upper part of the nozzle. The guide plate 9 is provided so as to surround the discharge hole 8, extends downward in parallel with the burner unit 2, and is open. Therefore, the rich mixture jetted from the discharge holes 8 is guided by the guide plate 9, is mixed with the combustion air flowing between the burner units 2 and is mixed, and is sent upward. In this manner, a light air-fuel mixture having a high air ratio is formed between the guide plates 9 facing each other, and is ejected upward from the light-side flame port 6 between the burner units 2. That is, the space between the guide plates 9 facing each other becomes the light mixture gas chamber 4 (hereinafter, this space is referred to as the light mixture gas chamber).

In the present embodiment, the air ratio is increased by remixing with the combustion air performed in the lean gas mixture chamber 4, and the excess air ratio is set to 2.7.

As a result, at the same time as the rich air-fuel mixture blows out from the deep-side flame opening 7 of each burner unit 2, the light-air-fuel mixture flows from between the flame forming surfaces 24 of the burner units (consisting of the light-side flame opening 6). The fuel is ejected and ignited by an ignition device (not shown) to perform light / dark combustion. In addition, a strip-shaped flame holding plate 10 is arranged in the light-side flame opening 6 in order to stably hold the flame.

Here, the rich mixture chamber 5 of the burner unit 2
The reason why the plurality of discharge holes 8 provided in the vicinity are located in the vicinity of the dark side flame outlet 7 will be described. The reason is that the rich air-fuel mixture, which is the basis of the light air-fuel mixture ejected from the discharge holes 8, is sufficiently mixed to form a rich air-fuel mixture having a uniform concentration. In other words, the rich air-fuel mixture in the burner unit 2 becomes more uniform as it gets closer to the deep-side flame opening 7, and the pressure distribution is also uniform. Therefore, by providing the discharge hole 8 in the vicinity of the deep-side flame opening 7, a rich air-fuel mixture having a stable concentration and amount can be obtained, which is used for generating a light air-fuel mixture.

A guide plate 9 for guiding the rich mixture from the discharge port 8 to the upstream of the light mixture chamber 4 is provided to obtain a sufficiently mixed light mixture. In other words, the rich mixture from the discharge hole 8 is guided to the upper stream below the light mixture chamber 4 by the guide plate 9 and mixed with the combustion air to form a light mixture. The mixing distance up to 6 can be sufficiently secured. Therefore, the concentration of the light mixture can be made uniform, and the pressure distribution to the light side flame outlet 6 can be made uniform.

Thus, NOx can be reduced by contact between the rich flame FR from the deep flame port 7 and the light flame FL from the light flame port 6. Moreover, in order to produce a lean mixture, first, a uniform rich mixture from the rich mixture chamber 5 is guided to the lower side of the light mixture chamber 4 and mixed with the combustion air to form an upward light side flame port 6.
In addition, the mixing distance can be effectively secured in a small space, and the mixing state can be improved. Further, since the burner units 2 integrally formed with the guide plate 9 are arranged at intervals, the number of parts and the number of manufacturing steps are reduced, and positioning is easy.

Since the rich mixture is guided below the light mixture chamber 4 by the guide plate 9 and intersects with the upward flow of the combustion air, the mixture is increased and the burner unit 2 is improved. Can be further shortened. As a result, the combustion device 1 itself can be made compact, and the mixing state of the lean mixture can be improved.

Also, in the conventional concentration combustion apparatus, the temperature of the flame of the burner unit 2 rises (because the combustion air is small).
However, in this apparatus 1, the rich mixture flows downward from the outer upper end of the burner unit 2, and the burner unit 2
The guide plate 9 attached to the upper end of the
Since the burner unit 2 is also cooled and plays a role of a heat sink, there is no fear of flashback.

In general, when performing lean-burn combustion, the combustion becomes unstable when the capacity (burning amount) is reduced. Therefore, the number of combustion burners may be switched when the capacity is small.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention. It is. For example, the guide plate 9 for guiding the rich mixture upstream of the light mixture chamber is not limited to being formed integrally with the burner unit 2. May be integrally formed and fitted to the bar unit 2 to secure the relationship between the flame holding plate 10 and the guide plate 9 and the burner unit 2. Further, the guide plate 9 is not limited to being formed integrally with the burner unit 2 so as to surround the discharge hole 8, and may be provided so as to partition toward the burner case 11.

Further, the shape of the guide plate 9 is not limited to the embodiment. For example, as shown in FIG. 3, an auxiliary plate 13 is provided so that the rich air-fuel mixture and the combustion air do not oppose each other and the combustion air is provided. The mixing property may be enhanced by being involved. Of course, the auxiliary plate 13 and the guide plate 9 may be formed integrally. Also, as shown in FIG. 3, in order to provide a uniform rich mixture to a light mixture, the shapes of the guide plate 9 and the flame holding plate 10 of the light side flame opening 6 are formed obliquely. The discharge hole 8 may be provided at a position closest to the dark side flame opening 7.

[0020]

As described above in detail, according to the combustion apparatus of the present invention, the lean air-fuel mixture can be made uniform without concentration unevenness, so that stable lean-burn combustion can be realized.
Ox generation can be suppressed. Moreover, it can be manufactured at low cost without having a complicated structure.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a combustion device as one embodiment.

FIG. 2 is a side sectional view of the burner unit according to the first embodiment of the present invention.

FIG. 3 is a schematic view of a combustion unit according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a conventional combustion device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustion apparatus 2 Burner unit 4 Light mixture chamber 5 Rich mixture chamber 6 Light flame port 7 Rich flame port 8 Discharge hole 9 Guide plate

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-353309 (JP, A) JP-A-6-117609 (JP, A) JP-A-4-124513 (JP, A) JP-A-4- 131605 (JP, A) JP-A-4-124512 (JP, A) JP-A-3-263501 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23D 14/02-14 / 08 F23D 14/64 F23C 11/00

Claims (2)

(57) [Claims] 1. A plurality of dense burners which inhale and mix a fuel gas and combustion air to eject a rich air-fuel mixture having a low air ratio from a rich-side flame outlet are arranged side by side at intervals. A light mixture having a higher air ratio than that of the rich mixture is ejected from between the rich burners to form a light-side flame opening next to the rich-side flame opening. The passage is a combustion device provided with a light-air mixture chamber that mixes a part of the rich air-fuel mixture of the rich-side burner and combustion air sent toward the light-side flame opening to generate the light-air mixture. A discharge port for ejecting a part of the rich mixture from the rich burner to the light mixture chamber is provided on an upper side surface of the rich burner, and the rich mixture ejected from the discharge hole is supplied to the rich side. Burner side
A combustion device, comprising: a guide plate for guiding along a surface to an upstream portion below the lean gas mixture chamber . 2. The above-mentioned light mixture chamber is provided by the above-mentioned guide plate.
The rich mixture guided to the flow collides with the combustion air
A contractor characterized by providing an auxiliary plate to prevent
The combustion device according to claim 1.