JPH09318018A - Premixture type gas burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a premixture type gas burner to reduce the generation of noise at a mixing part to mix together combustion air and fuel gas and achieve reduction of the generation of noise. SOLUTION: A premixture type gas burner comprises a duct 1 through which combustion air is received form an upper stream spot and to the downstream spot of which a burner element 2 is attached; and a mixing part 3 to receive the feed of fuel gas from a fuel gas feed piping and effect mixture with combustion air in the middle of the duct 1. The mixture part 3 is formed such that the interior of the duct 1 is formed approximately in the shape of an ejector having a nozzle part 5, a throat part 6, and a diffuser part 7. A fuel gas injection nozzle 9 is formed in the throat part 6 and the fuel gas injection nozzle 9 and a gas chamber 8 communicated with a fuel gas feed piping are arranged outside the throat part 6. A resonance preventing member 20 to have at least one of a function to diffuse an acoustic wave and a function to damp an acoustic wave is provided in the gas chamber 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a premix gas burner.

[0002]

2. Description of the Related Art As is well known, there is a type of gas combustion apparatus that uses a premixed mixture of fuel gas and combustion air in a predetermined ratio. It is roughly classified into a complete premixing type in which air is burned as it is and a partial premixing type in which combustion air is secondarily supplied to the premixed air for combustion. In such a gas combustor, obtaining a premixed mixture of fuel gas and combustion air uniformly improves the combustibility, NOx,
Since it produces an advantageous effect in reducing harmful exhaust substances such as CO, various inventions have been made in the conventional mixing mechanism.
There is a device. The mixing mechanism is basically performed by jetting fuel gas into the combustion air supply passage. However, the mere provision of the gas nozzle for injecting the fuel gas in the supply passage does not sufficiently mix the two. In order to eliminate this point, a long flow path is required after the gas nozzle, which is an obstacle to downsizing of the gas combustion device. Therefore, generally, around the gas nozzle or on the downstream side thereof, a baffle for disturbing the combustion air is provided, the mixing portion is bent, or an orifice member is arranged. . However, with this configuration, there is a problem that the length to the combustion section at the downstream end of the supply flow path cannot be shortened and pressure loss increases on the downstream side. Further, depending on the shape of the mixing portion, a vortex is generated in the combustion air flow, and noise due to the air flow,
It is a cause of vibration.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a premixing gas burner which reduces noise generated in a mixing section for mixing combustion air and fuel gas and achieves low noise. It is to be.

[0004]

SUMMARY OF THE INVENTION According to the present invention, combustion air is supplied from an upstream side, a burner element is attached to a downstream side, and a fuel gas is supplied from a fuel gas supply pipe. A mixing section for mixing with the combustion air on the way, wherein the mixing section forms the inside of the duct into a substantially ejector shape including a nozzle section, a throat section, and a diffuser section, and A fuel gas ejection hole is formed, and the fuel gas ejection hole and a gas chamber communicating with the fuel gas supply pipe are provided outside the throat portion, and a function of diffusing a sound wave and a sound wave are provided in the gas chamber. The problem described above is solved by a configuration in which a resonance preventing member having at least one of the functions of damping is provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The premixing type gas burner according to the present invention is provided with a mixing section for mixing combustion air and fuel gas in the middle of a duct to which combustion air is supplied. It has a substantially ejector shape including a throat portion and a diffuser portion. This gas burner is provided with a gas chamber communicating with the fuel gas supply pipe on the outside of the throat part, and the fuel gas is ejected from the gas ejection hole provided in the throat part of the mixing part via this gas chamber. This premixing type gas burner accelerates combustion air in the nozzle portion, and ejects fuel gas in the gas chamber through gas ejection holes by an ejector effect when the high-speed flow of the combustion air passes through the throat portion. Exerts the action of sucking. Then, the fuel gas is taken into the flow of the combustion air whose velocity has been increased, and both are mixed in the diffuser portion on the wake side. Here, the outside of the throat portion refers to the side separated from the center line side of the duct. The combustion air is supplied to the duct by an air supply unit such as a blower connected upstream. The burner element on the downstream side of the duct is
The part that performs the actual combustion by injecting the premixed gas is equipped with at least a member called a flame holder for that purpose. The member for attaching this flame holder to the duct and the shape of the flame holder itself. Including a member for maintaining.

The speed of the combustion air is increased as described above before it flows into the throat portion, but at the same time, noise such as whistling noise is generated by the flow of the combustion air flowing into the throat portion. Sometimes. This noise is mainly a resonance sound in the gas chamber. That is, the sound generated by the combustion air passing through the throat portion is repeatedly reflected between the opposing wall surfaces in the gas chamber to generate a resonance sound. Therefore, in the present invention, a resonance preventing member having at least one of a function of diffusing a sound wave and a function of attenuating the sound wave is provided in the gas chamber. The anti-resonance member diffuses or attenuates the sound wave propagated toward the surface thereof to reduce the intensity of the sound wave reflected from the surface of the anti-resonance member, thereby preventing resonance in the gas chamber. In other words, by blocking this reflection, the standing wave is attenuated and the noise is prevented. That is, the sound wave is a compressional wave using air as a medium, and, for example, between two parallel wall surfaces facing each other, the sound wave is alternately reflected on each wall surface, and a frequency corresponding to the distance between the wall surfaces, and A standing wave (also called a standing wave) with a frequency that is an integral multiple of this frequency is generated, and this standing wave becomes a resonance sound. Therefore, the resonance preventing member prevents the occurrence of the noise by preventing the reflection of the sound wave from being repeatedly performed, thereby suppressing the generation of the standing wave. The above resonance preventing member includes a case where it is provided on all wall surfaces in the gas chamber and a case where it is provided on one wall surface of the gas chamber. In short, the resonance preventing member is provided on at least one of the wall surfaces in the gas chamber. That is, by providing the anti-resonance member on all of the wall surfaces in the gas chamber, it is possible to reliably prevent the generation of resonance noise, but the opposite wall surface where the strongest standing wave is generated is extracted and the opposite wall surface is extracted. It is also possible to significantly reduce the resonance sound at the minimum cost by providing it on at least one of the above.

Examples of the resonance preventing member having a function of diffusing a sound wave include a corrugated plate, a concave-convex plate, a curved plate, and an inclined plate. The anti-resonance member does not reflect the sound wave propagating toward the anti-resonance member in a direction opposite to the propagation direction but in a different direction, and thus alternates between the two wall surfaces as described above. Never reflected on. In particular, the corrugated plate, the uneven plate, and the curved plate diffuse the sound waves by reflecting them in a large number of directions, so that the suppression effect is large. On the other hand, the inclined plate does not reflect in the direction opposite to the propagation direction but reflects in one different direction, thereby suppressing the generation of standing waves. Here, the inclined plate is an inclination with respect to the opposing wall surfaces, and thus the two surfaces have a predetermined angle with each other so that the wall surfaces that are parallel to each other are eliminated so that standing waves are generated. However, the corrugated plate and the uneven plate have the same function in that the wall surfaces that are parallel to each other are eliminated. Here, in the present specification, the uneven plate refers to a plate having a large number of irregularities. Even if a flat plate is provided with a concave portion or a convex portion, as a result, the convex portion is
Alternatively, since it becomes a concave portion, such a thing is also included.

Examples of the resonance preventing member having a function of attenuating sound waves include, for example, fibrous porous materials such as glass wool and steel wool, and foaming porous materials such as foamed ceramics and urethane foams. In addition to the well-known sound absorbing material, a perforated plate having a large number of through holes formed therein can be used. Such an anti-resonance member suppresses the generation of the standing wave and prevents the generation of the noise by attenuating the sound wave propagating toward the anti-resonance member on its surface or inside. Here, the perforated plate serves as a resistance to the compressional wave and reduces the reflection surface of the sound wave to attenuate the sound wave. Therefore, this perforated plate is provided in a state in which it is kept in a predetermined distance without being brought into close contact with the inner wall surface of the gas chamber.

Further, examples of the resonance preventing member having a function of diffusing a sound wave and a function of attenuating the sound wave include a corrugated plate-shaped perforated plate and an uneven perforated plate.

Here, the resonance preventing member having the above-mentioned respective functions includes a member having the same function or a combination of members having different functions. Further, the resonance preventing member includes not only one provided on the wall surface forming the gas chamber but also a structure forming the wall surface of the gas chamber by the resonance preventing member itself.

Further, according to the present invention, as the resonance preventing member, the above sound absorbing material is arranged on the back surface side of the perforated plate. In this configuration, the perforated plate,
The sound absorbing material exerts the above-described effect of reducing the resonance sound, and the perforated plate functions as a holding member that holds the sound absorbing material at a predetermined position.

The sound generated in such a burner duct depends on the speed (wind speed) of the combustion air sent from the blower, and a change in this speed generates sound in various frequency bands. Like the anti-resonance member,
Noise of various frequencies can be reduced by diffusing or attenuating sound waves.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a premixing gas burner according to the present invention will be specifically described below with reference to the drawings. 1 is a cross sectional view showing the structure of the first embodiment of the present invention, FIG. 2 is a cross sectional view taken along the line II-II of FIG. 1, and FIG. 3 is a line III-III of FIG. It is explanatory drawing of the cross section along.

In the drawings, a premixed gas burner according to the present invention is provided with a burner element 2 for injecting and burning a premixed air, downstream of a cylindrical duct 1 forming a flow path for combustion air. . On the other hand, on the upstream side of the duct 1, a blower (not shown) is connected as an air supply means, and the blower supplies the combustion air.

In the middle of the duct 1, a mixing section 3 having a substantially ejector shape is provided. In other words, a similar throttle member 4 forming a pair is arranged at a predetermined position of the duct 1 so as to face each other, and a mixing portion 3 having a substantially ejector shape is formed in the central portion. In the first embodiment, the width of the throttle member 4 is substantially equal to the inner width of the duct 1, and the facing throttle member 4 causes the inside of the duct 1 from the upstream side in the flow direction of the combustion air. The nozzle portion 5 in which the flow passage cross-sectional area gradually decreases, the throat portion 6 in which the flow passage cross-sectional area is substantially the same, and the diffuser portion 7 in which the flow passage cross-sectional area gradually increases are configured. A gas chamber 8 is formed in the space outside the throttle member 4, that is, inside the duct 1. A large number of small holes are formed as gas ejection holes 9 in the throat portion 6 corresponding to the mixing portion 3.

A fuel gas supply pipe 10 for supplying a fuel gas is connected to the gas chamber 8 from outside the duct 1. The fuel gas supply pipe 10 may be connected from any direction such as the left-right direction and the front-back direction of the duct 1, but in the first embodiment, as shown in FIG. A through hole 11 communicating with the gas chamber 8 is formed on the wall surface, and the branch pipe 1 is formed so as to cover the through hole 11.
2 is connected, and the fuel gas supply pipe 1 is connected to the branch pipe 12.
0 is connected.

According to the gas burner having the above construction, the duct 1
When the combustion air supplied from the upstream end of (1) passes through the mixing section 3, the flow is once throttled in the nozzle section 5, then passes through the throat section 6 and expands in the diffuser section 7. Therefore, the combustion air has a high-speed air flow in the throat portion 6, and in the middle of the throat portion 6, the combustion gas is supplied from the fuel gas supply pipe 10 to the gas chamber 8 and the gas ejection holes 9
The fuel gas supplied via the is effectively sucked into the throat portion 6. When it is expanded in the diffuser portion 7, it is efficiently mixed with combustion air and then supplied as a premixed air to the burner element 2 at the downstream end of the duct 1. That is, in the premixed gas burner having this configuration, the substantially ejector-shaped mixing portion 3 is provided at a predetermined position of the duct 1, and the gas ejection hole 9 of the fuel gas supply pipe 10 is opened in this mixing portion 3, so that the throat portion is formed. The high-speed airflow of 6 can promote the mixing of the combustion air and the fuel gas to generate a uniform premixed air-fuel mixture. Further, since the flow velocity of the combustion air in the mixing section 3 is increased, the suction force of the fuel gas is increased by the ejector effect, the gas supply pressure in the fuel gas supply pipe 10 can be set low, and therefore the piping cost can be reduced.

Now, in such a premixing type gas burner, the structure of the gas chamber 8 will be described in detail. As shown in FIGS. 1 and 3, in the first embodiment, by providing a partition wall 13 in the direction crossing the duct 1 inside the throttle member 4, the inside of the nozzle portion 5 and the throat portion 6 is gas-filled. It is divided as a chamber 8. In the first embodiment, the resonance preventing member 20 is provided on the wall surface facing the throat portion 6 in the gas chamber 8. The resonance preventing member 20 in the first embodiment is a perforated plate 21 having a large number of small holes such as a so-called punching metal.
And a sound absorbing material 22 such as glass wool. The porous plate 21 is arranged in the gas chamber 8 between the wall surface forming the throat portion 6 and the wall surface forming the duct 1. The perforated plate 21 acts as a resistance to a sound wave (air compression wave) propagating between the wall surface forming the throat portion 6 and the wall surface forming the duct 1, and the area for reflecting the sound wave is reduced by the small holes. By doing so, the sound wave is attenuated. on the other hand,
The sound absorbing material 22 is provided on the back side of the porous plate 21 and the duct 1
Is filled between the wall surface 1a and the wall surface 1a. In this configuration, the perforated plate 21 functions as a holding member for holding the sound absorbing material 22 in a fixed position on the wall surface 1a forming the duct 1.

In the above structure, when the combustion air supplied into the duct 1 passes through the throat section 6 as described above, a resonance sound is about to be generated in the gas chamber 8. Here, this resonance sound is mainly due to the sound transmitted to the inside of the gas chamber 8 from the fuel gas ejection holes 9 provided in the throat portion 6. That is, sound (sound wave) is a compressional wave using air as a medium, and when reflected alternately between substantially parallel wall surfaces facing each other, a frequency corresponding to the distance between the wall surfaces and a frequency of an integral multiple of this frequency are generated. A standing wave is generated, and this standing wave becomes a resonance sound. However, in the premixed gas burner according to the invention, the sound wave propagating in the gas chamber 8 due to the resonance preventing member 20, particularly the sound wave propagating between the wall surface forming the throat portion 6 and the wall surface forming the duct 1. Is attenuated in the middle of the process to prevent resonance in the gas chamber 8. In other words, by inhibiting the propagation of this sound wave, it is possible to suppress the generation of standing waves, thereby preventing the generation of resonance sound.

In the premixed gas burner having the above structure, the resonance preventing member 20 is a combination of a perforated plate 21 having a function of attenuating sound waves and a sound absorbing material 22, but in the present invention, the perforated plate 21 is used. , Or sound absorbing material 22
Any one of the above may be used. Further, the first embodiment described above is an embodiment of the resonance preventing member 20 that attenuates sound waves.
0 includes one having a function of scattering a sound wave, which will be described below. 4 is a sectional explanatory view showing the structure of the second embodiment of the present invention, FIG. 5 is a sectional explanatory view showing the structure of the third embodiment of the present invention, and FIG. 6 is the fourth embodiment of the present invention.
7 is a sectional explanatory view showing the constitution of the embodiment, and FIG. 7 is a sectional explanatory view showing the constitution of the fifth embodiment of the present invention. In each of the following embodiments, the gas chamber 8 is formed by providing a partition wall 13 having a substantially U-shaped cross section on the back surface side of the wall surface forming the throat portion 6.

First, in the second embodiment shown in FIG. 4, the resonance preventing member 20 is a corrugated diffusion plate 23. In the gas chamber 8, the diffusion plate 23 is attached along substantially the entire surface of the wall surface 13 a of the partition wall 13 that faces the gas ejection hole 9.
Here, the arrangement of the curved portion of the diffusion plate (corrugated plate) is
The ridgeline direction of the corrugated plate may be arranged along the flow direction of the combustion air in the duct, or may be provided in a direction orthogonal to the air flow direction of the combustion air. In the premixed gas burner of the second embodiment, since the resonance prevention member 20 is the corrugated plate-shaped diffusion plate 23, the sound wave propagating toward the diffusion plate (resonance prevention member) 23 has the direction of propagation. Since it does not reflect in the opposite direction but in a number of different directions, it does not reflect alternately between the two walls as described above. That is, unlike the flat plate, the corrugated plate-like diffusion plate 23 diffuses sound waves by reflecting them in a number of different directions, so that the reflected sound waves are attenuated. Here, the diffusion plate 20
In addition to the corrugated plate shape described above, a perforated plate or a corrugated plate-shaped perforated plate may be used. That is, when the corrugated plate is used as described above, the sound waves are mainly diffused on the surface thereof, and when the perforated plate is used, the reflectance itself of the sound wave is mainly lowered to exhibit the above-mentioned effect. Furthermore, this diffusion plate 20
In addition to the corrugated plate and the perforated plate described above, the corrugated plate may be in the form of an uneven plate having a large number of convex portions, concave portions, or both formed on the surface.

Next, in the third embodiment shown in FIG. 5, the resonance preventing member 20 is provided on the entire surface of the gas chamber 8, and the entire surface of the gas chamber 8 is constituted by an inclined plate. That is, among the wall surfaces in the gas chamber 8, the wall surfaces facing each other are formed by inclining at a predetermined angle, and the parallel wall surfaces are removed. With this configuration, there is no place where the sound wave is repeatedly reflected in the opposite direction by 180 degrees, and the sound wave is reflected and propagated in various directions, so that the generation of the standing wave can be suppressed. In the third embodiment, standing walls are prevented from being generated by making opposite wall surfaces have a predetermined angle with each other to eliminate parallel wall surfaces, but the parallel wall surfaces are eliminated. In terms of points, in addition to the corrugated plate-shaped diffuser plate 23, the uneven plate-shaped diffuser plate has the same function. Note that, in FIG. 5, two opposing wall surfaces located in a direction perpendicular to the paper surface are inclined with respect to each other, and similarly to the second embodiment shown in FIG. 4, the corrugated plate-shaped diffusion plate 23 is used. Or a porous sound absorbing material 22 such as glass wool as described above.
May be arranged.

Next, in the fourth embodiment shown in FIG. 6, among the wall surfaces forming the gas chamber 8, at least the surface facing the throat portion 6 is formed into a curved shape so as to be parallel to each other. The wall surface is removed to prevent the generation of standing waves as in the third embodiment. That is, in the third embodiment, the curved facing surface eliminates the place where the sound wave is reflected in the opposite direction by 180 degrees, diffuses the sound wave, and reflects the sound wave in the diffusing direction, thus suppressing the formation of the standing wave. To be done. still,
The formation of such curved curved facing surfaces can be easily configured by using, for example, a member obtained by appropriately cutting a pipe-shaped member along the axial direction.

Further, although the resonance preventing member 20 is attached to the wall surface forming the gas chamber 8, as in the third embodiment shown in FIG. 5 and the fifth embodiment shown in FIG. The resonance preventing member 20 itself may form the wall surface of the gas chamber 8. In the fifth embodiment, the partition plate 13 having a U-shaped cross section is constituted by the diffusion plate 23 similar to that of the second embodiment. In the fifth embodiment, since the partition wall 13 that constitutes the gas chamber is formed by the resonance preventing member 20 itself, there is an advantage that the number of parts can be reduced and the structure can be simplified.

Here, the resonance preventing member 20 having each of the above-mentioned functions may be configured to have the same function or a combination of different functions. That is, the effect of reducing resonance is enhanced by disposing the diffusion plate 20 on the inclined facing surface or the curved facing surface. At this time, the diffusion plate 20 is a corrugated plate-shaped or uneven diffusion plate as described above. Further, in the present invention, the sound absorbing material 22 is arranged on the surface of the gas chamber 8 facing the throat portion 6 to prevent the standing wave from being reflected and to attenuate the intensity of the sound wave reflected toward the facing surface. By doing so, resonance is prevented.

In the above-described first to fifth embodiments, the resonance preventing member 20 is provided at a position facing the wall surface forming the throat portion 6, and in the third to fifth embodiments, the resonance preventing member 20 is provided at the position. It is also provided on the adjacent wall. That is, in the present invention, it may be provided on one of the wall surfaces forming the gas chamber 8 or on all the wall surfaces. In short, the resonance preventing member 20 may be provided on at least one wall surface in the gas chamber 8. As described above, by providing the resonance preventing member 20 on all of the wall surfaces in the gas chamber 8, it is possible to reliably prevent the generation of resonance sound. For example, between the wall surface forming the throat portion 6 and the wall surface facing the wall surface. In the case where a strong standing wave is generated in the wall surface and a resonance sound is generated thereby, the resonance preventing member 20 is provided on at least one wall surface of the opposing wall surfaces, so that the resonance sound can be significantly reduced at a minimum cost. Reduction can be achieved.

The sound generated in the burner duct 1 as described above depends on the velocity of the combustion air sent from the blower. For example, when the premixed gas burner is for a boiler, sound in various frequency bands is generated due to a change in speed at the time of starting the boiler or transition to combustion, but in the present invention, as described above, In addition, by diffusing or attenuating this sound wave, the above-described noise reduction effect is exhibited at various frequencies.

[0028]

As described above, according to the premixing type gas burner of the present invention, the resonance preventing member having at least one of the function of diffusing sound waves and the function of attenuating sound waves is provided in the gas chamber. By providing, it is possible to suppress the formation of standing waves in the gas chamber,
When the combustion air passes through the throat portion, it is possible to prevent generation of noise caused by increasing the speed. Further, according to the premixed gas burner of the present invention, the resonance prevention member suppresses the generation of standing waves, and therefore the frequency band of noise changes according to the flow velocity of the combustion air in the duct. However, the reduction effect is exhibited regardless of this frequency band. Further, in the present invention, the resonance preventing member is configured such that the sound absorbing material is arranged on the back surface side of the perforated plate, whereby the above noise reducing effect is exhibited, and the perforated plate places the sound absorbing material at a predetermined position. Since it functions as a holding member for holding, the structure can be simplified.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view showing the structure of a first embodiment of the present invention.

FIG. 2 is an explanatory view of a cross section taken along line II-II of FIG.

FIG. 3 is an explanatory diagram of a cross section taken along line III-III in FIG.

FIG. 4 is an explanatory sectional view showing the structure of the second embodiment of the present invention.

FIG. 5 is an explanatory sectional view showing the structure of the third embodiment of the present invention.

FIG. 6 is an explanatory sectional view showing the structure of the fourth embodiment of the present invention.

FIG. 7 is an explanatory sectional view showing the structure of the fifth embodiment of the present invention.

[Explanation of symbols]

 1 Duct 2 Burner Element 3 Mixing Part 4 Throttle Member 5 Nozzle Part 6 Throat Part 7 Diffuser Part 8 Gas Chamber 9 Fuel Gas Injection Hole 10 Fuel Gas Supply Piping 20 Resonance Prevention Member 21 Perforated Plate 22 Sound Absorbing Material 23 Diffuser Plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Oda 7 Horie-cho, Matsuyama-shi, Ehime Prefecture Miura Industrial Co., Ltd.

Claims (3)

[Claims] 1. A combustion air is supplied from an upstream side, a duct 1 having a burner element 2 attached to a downstream side, and a fuel gas is supplied from a fuel gas supply pipe 10, and the combustion is performed in the middle of the duct 1. And a mixing section (3) for mixing with the working air. The mixing section (3) forms the inside of the duct (1) into a substantially ejector shape including a nozzle section (5), a throat section (6) and a diffuser section (7). A fuel gas ejection hole 9 is formed in the portion 6, and the fuel gas ejection hole 9 and the fuel gas supply pipe 10 are provided outside the throat portion 6.
A gas chamber 8 communicating with the gas chamber 8 is provided.
A premixing gas burner comprising a resonance preventing member 20 having at least one of a function of diffusing a sound wave and a function of attenuating the sound wave. 2. The premixing gas burner according to claim 1, wherein the resonance preventing member 20 has a sound absorbing material 22 arranged on the back surface side of a perforated plate 21. 3. The premix type gas burner according to claim 1, wherein the resonance prevention member 20 is a corrugated plate 21.