JP3150233B2 - Combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called rich / lean combustion, in which an excess fuel mixture (rich mixture) and an excess air mixture (light mixture) are simultaneously burned to suppress the generation of nitrogen oxides (NOX). Related to the 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, as shown in FIG. 4, there has been proposed a light-and-dark combustion apparatus in which rich burners RB for emitting a rich air-fuel mixture and light burners LB for emitting a light air-fuel mixture are alternately arranged in a line and burn simultaneously. I have. In this case, oxygen is insufficient at the base of the flame from the deep burner RH of the deep burner RB (hereinafter referred to as rich flame), and the light burner LH of the light burner LB is located above.
Exhaust gas of a flame (hereinafter, referred to as a lean 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 lowered and the generation of NOX is suppressed, and the low NOX as a whole is achieved by a synergistic effect of these.

[0004]

However, in order to produce a lean air-fuel mixture, the diameter of the throat LS (the inlet for fuel gas and combustion air) of the lean burner LB must be very large. For example, when the input of the light burner LB is the same as the input of the dark burner RB, and the air ratios are 2.7 (light mixture) and 0.3 (rich mixture), respectively, a desired amount of air is obtained. Therefore, the opening area of the throat LS of the light side burner LB is set to 9 of the throat RS of the dark side burner RB.
Must be doubled. Further, not only the throat LS but also the light-side burner LB itself must be enlarged. In addition, simply increasing the size will deteriorate the mixing state. When the mixture state of the light air-fuel mixture is poor, flashback occurs in the dense portion, and the combustion speed is low in the thin portion, so that combustion is not completed and unburned gas is discharged. As described above, in the conventionally proposed combustion apparatus, it is almost impossible to actually perform the concentration combustion with the configuration shown in FIG. 4, and it is impossible to increase the air ratio on the light side. It is. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, to suppress an increase in the size of a device associated with rich and light combustion, and to improve the mixing of a lean gas mixture.

[0005]

A combustion apparatus according to the present invention which solves the above-mentioned problems is characterized in that a fuel gas and combustion air are suction-mixed and a rich mixture having a low air ratio is ejected from a rich-side flame opening. A burner in which 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 the rich burners to form a light side flame opening next to the rich side flame opening. A light mixing unit for sucking and mixing the fuel gas and the combustion air from an upstream side thereof and discharging the air / fuel mixture from a discharge port; A re-mixing unit that mixes the combustion air sent to the light side flame port direction with the air-fuel mixture to make a light air-fuel mixture with a high air ratio,
The light mixing unit is formed integrally with the rich burner, and the inlet of the fuel gas and the combustion air is located above the inlet of the rich burner, and the outlet is located at the lowermost position. The gist is that it was located.

[0006]

According to the combustion apparatus of the present invention having the above-described structure, a light-side flame port is formed next to the rich-side flame port, and the air-fuel mixture having a different air ratio is ejected from each flame port to burn. The air-fuel mixture spouting from the side flame outlet is created as follows. That is,
First, the fuel gas and the combustion air are mixed in the light mixing unit, and the air-fuel mixture is guided downward, discharged from the discharge port, mixed with the combustion air in the remixing section, and the air ratio is increased to increase the light side flame port. Send to Therefore, the mixed state of the light air-fuel mixture is improved by mixing twice. Further, since the mixture is sent downward in the light mixing unit and then sent upward in the remixing section and guided to the light side flame opening, a sufficient mixing distance can be secured with a small space.
Further, since the light mixing unit is formed integrally with the dark side burner, it is not necessary to arrange the light mixing units individually between the dark side burners, and the arrangement interval of the dark side burners can be narrowed. In addition, since the intake port of the light mixing unit is located above the intake port of the burner on the dark side, downsizing in the vertical direction can be achieved.

[0007]

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. The combustion device 1 includes a plurality of burner units 10.
Are arranged in a line, and combustion air is supplied from below.

As shown in FIGS. 2 and 3, the burner unit 10 has a dark side burner 2 on one side with a central partition plate 11 interposed therebetween.
0 and a light mixing unit 30 integrally formed on the other side. FIG. 2A shows the dark side burner 20.
3B is a schematic perspective view of the burner unit as viewed from the side where the light mixing unit is formed, and FIG. 3A is a schematic perspective view of the burner unit as viewed from the side where the light mixing unit is formed. FIG. FIG. 4B is a schematic side view of the burner unit, and FIG. 4C is a schematic front view of the burner unit as viewed from the side where the light mixing unit is formed.

A throat 21 serving as a fuel gas inlet to the rich burner 20 is provided at a lower portion on one side of the burner unit 10.
A fuel gas is injected and supplied from a gas nozzle 42 provided on the gas nozzle table 40, and combustion air (primary air) is sucked along with the fuel gas. In the drawings, the solid arrows indicate the flow of the fuel gas, and the dashed arrows indicate the flow of the combustion air.
The downstream side of the thick throat 21 is bent upward to mix the mixing chamber 2
2 (hereinafter referred to as the dark side mixing chamber), and the dark side mixing chamber 2
A plurality of flame outlets 23 (hereinafter referred to as dark side flame outlets) on the head of 2
Is formed. Therefore, the fuel gas and the combustion air are mixed while passing through the rich-side throat 21 and the rich-side mixing chamber 22, and the mixture becomes the rich-side flame 23
Spouts upward from. The air ratio of this air-fuel mixture is set low, and is set to 0.5 in this embodiment. Hereinafter, this mixture is referred to as a rich mixture.

On the other hand, in the light mixing unit 30 provided on the back side of the dark side burner 20, a throat 31 (hereinafter referred to as a light side throat) is formed in the center of the burner unit 10 in the lateral direction. That is, the light-side throat 31 is provided above and parallel to the dark-side throat 21. Then, a fuel gas is injected and supplied from the gas nozzle 43 to the light-side throat 31, and the combustion air is sucked along with the fuel gas. The downstream side of the light-side throat 31 is bent downward so that the mixing chamber 3
2 (hereinafter referred to as the light-side mixing chamber). A plurality of air-fuel mixture discharge ports 33 are formed in a row on the lower side surface of the light-side mixing chamber 32. Therefore, the fuel gas and the combustion air sucked from the light-side throat 31 are sent in a downward direction (upstream of the combustion air supplied by a blower described later) to be a mixture, and are ejected from the discharge port 33. . That is, the light mixing unit 30 forms a flow path such that the dark side burner 20 is turned upside down, and blows out the air-fuel mixture in the lowermost part of the burner unit 10 in the lateral direction.

As shown in FIG. 1, the respective burner units 10 are arranged in parallel in the burner case 2 at predetermined intervals and are accommodated in the combustion chamber 3. A blower (not shown) is provided below the combustion chamber 3 so as to supply combustion air into the combustion chamber 3. And burner case 2
A current plate 4 (for example, punching metal) is provided on the bottom surface, and the combustion air that has passed through the current plate 4 flows upward between the burner units 10. Therefore, the air-fuel mixture ejected from the air-fuel mixture discharge port 33 of the light mixing unit 30 collides with the combustion air flowing between the burner units 10 and is mixed and sent upward. Thus, a light air-fuel mixture having a high air ratio is produced in this space, and is ejected upward from between the burner units 10. That is, the space 50 between the burner units 10 serves as the remixing unit of the present invention. Hereinafter, this space 50 is referred to as a remixing unit 50. In the present embodiment, the air ratio in the light mixing unit 30
The value is set to 0.5 similarly to 0, and is increased to 2.7 by mixing the combustion air in the remixing section 50. The light mixing unit 3
The air ratio at 0 may be slightly higher than the air ratio of the dark side burner 20 to reduce the second air dilution degree. Of course, the air ratio of each of the mixing chambers 22, 32 and the remixing section 50 is not limited to these.

As a result, the dark side flame port 2 of each dark side burner 20
3 at the same time that the rich mixture gushes out,
A light air-fuel mixture is blown out from between the 0 flame port forming surfaces 24 (which becomes the light-side flame port 51), and is ignited by an ignition device (not shown) to perform light-dark combustion. Note that a strip-shaped flame holding plate 52 is provided in the light-side flame port 51 to stably hold the flame.

Thus, the rich flame FR from the deep flame outlet 23
NO due to contact with the light flame FL from the light side flame port 51
X can be planned. Moreover, to make a light mixture,
First, the fuel gas and the combustion air are mixed in the lean mixing unit 30, and the air-fuel mixture is guided downward (upstream of the combustion air). The remixing unit 50 further mixes the combustion air and guides the air upward. Therefore, a sufficient mixing distance can be ensured in a small space, and the mixing state can be improved. Furthermore, since the burner unit 10 in which the dark side burner 20 and the light mixing unit 30 are integrally formed is arranged at intervals, the number of parts and the number of manufacturing steps are reduced, positioning is easy, and the dark side burner 20 Can be narrowed. If a separate light mixing unit is provided between the dark side burners 20, the arrangement interval of the dark side burners 20 becomes large, and not only the apparatus becomes large, but also the combustion performance deteriorates.

Further, the dark side burner 20 and the light mixing unit 3
0 is provided on the left and right sides of the flow path, and the thick throat 21 is provided below the light throat 31 so that the flow of each air-fuel mixture crosses up and down. The length can be shortened. As a result, it is possible to improve the mixing state of the lean gas mixture while keeping the combustion device itself compact.

Further, in the conventional concentration combustion apparatus, there is a concern that the temperature of the flame of the rich side burner rises (because the amount of combustion air is small) and the temperature of the rich mixture rises, causing flashback. Then, the remixing section 5 around the dark side burner 20
Since the lean air-fuel mixture flows to zero, the rich-side burner 20 is cooled, and there is no fear of flashback.

A fuel gas supply pipe (not shown) for the rich burner 20 and a fuel gas supply pipe (not shown) for the light mixing unit 30 are provided independently, and an electromagnetic valve for opening and closing them is provided. A configuration in which switching is performed according to the amount of combustion may be adopted. In general, when performing concentration combustion, combustion becomes unstable when the capacity (combustion amount) is reduced. Therefore, when the capacity is small, the fuel supply to the light mixing unit 30 is cut off, and only the combustion air is ejected from the light side flame port 51, so that Bunsen combustion with a high turndown ratio is performed to perform stable combustion. It is. In the case of such a small capacity, there is no problem because the amount of combustion itself is small and the amount of generated NOX is also small. Also, instead of switching to Bunsen combustion, the number of combustion burners may be switched to adjust the capacity while maintaining the rich and light combustion. In this case, it is desirable to prevent the lean mixture from slipping (ie, the raw gas is released without completing the combustion) by setting the both ends to a rich flame.

The embodiments of the present invention have been described above.
The present invention is not limited to these embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

[0019]

As described above in detail, according to the combustion apparatus of the present invention, it is possible to suppress the size of the apparatus and to improve the mixing state of the lean mixture. As a result, stable lean combustion can be realized, and the generation of NOX can be suppressed.

[Brief description of the drawings]

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

FIG. 2 is a schematic perspective view of a burner unit.

FIG. 3 is a front view, a side view, and a rear view of the burner unit.

FIG. 4 is a schematic perspective view of a conventional combustion device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Combustion apparatus, 10 ... Burner unit, 20 ... Rich side burner, 21 ... Rich side throat, 22 ... Rich side mixing chamber,
23 ... dark side flame outlet, 30 ... light mixing unit, 31 ... light side throat, 32 ... light side mixing chamber, 33 ... air / fuel mixture discharge port
50: Remixing part, 51: Light side flame outlet.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-323513 (JP, A) JP-A-6-40618 (JP, A) JP-A-6-94220 (JP, A) JP-A-4- 186002 (JP, A) JP-A 59-163721 (JP, U) JP-A 44-17414 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23D 14/02-14 / 08 F23C 11/00 329-330

Claims (1)

(57) [Claims] 1. A rich burner that inhales and mixes a fuel gas and combustion air to blow out a rich air-fuel mixture having a low air ratio from a rich-side flame outlet with a space therebetween. A combustion device in which a light-side flame port is formed next to the rich-side flame port by injecting a light-air mixture having a higher air ratio than the rich-air mixture, A light mixing unit that inhales and mixes a fuel gas and combustion air from its upstream side and discharges the air-fuel mixture from a discharge port; and a combustion unit that is sent to the discharged air-fuel mixture in the direction of the light-side flame port. A light-mixing unit that mixes air into a lean mixture having a high air ratio.The lean-mixing unit is formed integrally with the rich-side burner, and serves as an inlet for the fuel gas and combustion air. The discharge port is located at the lowermost position while being positioned above the suction port of the dark side burner. A combustion device characterized by the above-mentioned.