JP3717009B2 - Premixed gas burner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a premixed gas burner.
[0002]
[Prior art]
As is well known, there is a type of gas combustion apparatus that uses a premixed gas in which fuel gas and combustion air are mixed at a predetermined ratio. It is broadly classified into a mixed type and a partial premixed type in which combustion air is secondarily supplied to the premixed gas and burned. In such a gas combustion apparatus, obtaining a premixed gas in which fuel gas and combustion air are uniformly mixed has an advantageous effect on improving combustibility and reducing harmful emissions such as NOx and CO. Therefore, there have been various inventions and devices regarding the mixing mechanism for that purpose.
[0003]
The mixing mechanism is basically performed by ejecting fuel gas into the combustion air supply passage. However, if a gas nozzle for jetting fuel gas is simply provided in the supply channel, mixing of the two is insufficient. In order to eliminate this point, a long flow path is required on the downstream side of the gas nozzle, which is an obstacle to downsizing the gas combustion apparatus.
[0004]
Therefore, generally, there are provided means such as providing a baffle plate for disturbing the combustion air around the gas nozzle or downstream thereof, bending the mixing portion, or arranging an orifice-like member. I'm taking it. However, in this configuration, the length to the combustion section at the downstream end of the supply channel cannot be shortened, and there is a problem that pressure loss increases on the downstream side. Furthermore, depending on the shape of the mixing section, a vortex flow is generated in the combustion air flow, which causes noise and vibration due to the combustion air flow.
[0005]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to reduce the noise generated in the mixing section for mixing the combustion air and the fuel gas in the premixed gas burner, thereby achieving low noise.
[0006]
[Means for Solving the Problems]
The present invention has been made in order to solve the above-mentioned problems. The invention according to claim 1 is characterized in that a combustion air supply is received from the upstream side, a duct having a burner element attached to the downstream side, and a fuel gas supply A mixing unit that receives fuel gas from a pipe and mixes fuel gas and combustion air in the middle of the duct, and the mixing unit includes a nozzle unit, a throat unit, and a diffuser unit, and the throat unit noise to thereby form the fuel gas discharge holes, the gas chamber to the fuel gas injection hole and communicating with the fuel gas supply pipe to the outside of the throat portion is provided, the combustion air generated when passing through the throat portion to prevent the resonance preventing member having a function of attenuating sound waves in the gas chamber is provided, the resonance preventing member comprises a perforated plate and sound absorbing material, the perforated plate and the gas chamber Is characterized in that a said sound absorbing material between the walls.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described. The premixed gas burner according to the present invention includes a mixing portion of combustion air and fuel gas in the middle of a duct to which combustion air is supplied. The mixing portion includes a nozzle portion, a throat portion, and a diffuser portion. , Has the function of ejector. A gas chamber communicating with the fuel gas supply pipe is provided outside the throat portion, and the fuel gas is ejected from the fuel gas ejection hole provided in the throat portion via the gas chamber.
[0008]
The premixed gas burner accelerates combustion air in the nozzle portion, and ejects the fuel gas in the gas chamber by the ejector effect when a high-speed flow of the combustion air passes through the throat portion. It acts to suck through the hole. And the said fuel gas is taken in into the flow of the combustion air which raised the speed, and both mix in the said diffuser part downstream. Supply of combustion air to the duct is performed by air supply means such as a blower connected to the upstream side. The burner element on the downstream side of the duct is a portion that ejects premixed gas and performs actual combustion, and includes a flame holder for that purpose.
[0009]
Here, the speed of the combustion air is increased as described above until it flows into the throat portion. At the same time, noise such as whistling noise is generated by the combustion air flow flowing into the throat portion. May occur. This noise is mainly 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, thereby generating a resonance sound.
[0010]
Therefore, in the present invention, a resonance preventing member having at least one of a function of diffusing sound waves and a function of attenuating sound waves is provided in the gas chamber. The resonance preventing member diffuses or attenuates the sound wave propagated toward the surface thereof, thereby reducing the intensity of the sound wave reflected from the surface of the resonance preventing member, thereby preventing resonance in the gas chamber. In other words, the standing wave is attenuated by preventing the reflection of the sound wave, thereby preventing the generation of the noise.
[0011]
That is, the sound wave is a dense wave using air as a medium. For example, between two parallel wall surfaces facing each other, the sound wave is alternately reflected on each wall surface, and thus a frequency corresponding to the distance between the wall surfaces and this frequency. A standing wave (also called a standing wave) is generated, and this standing wave becomes a resonance sound. Therefore, the resonance prevention member prevents the generation of standing waves by preventing the sound waves from being repeatedly reflected, thereby preventing the generation of the noise.
[0012]
The resonance prevention member may be provided on all the wall surfaces in the gas chamber, or may be provided on one wall surface of the gas chamber, and the resonance prevention member may be provided on at least one of the wall surfaces in the gas chamber. Provided. That is, by providing the resonance preventing member on all the wall surfaces in the gas chamber, it is possible to reliably prevent the generation of resonance noise, but extract the opposing wall surface where the strongest standing wave is generated. By providing it on at least one of the opposing wall surfaces, it is possible to significantly reduce the resonance noise at the minimum cost.
[0013]
Examples of the anti-resonance member having a function of diffusing sound waves include a corrugated plate, an uneven plate, a curved plate, and an inclined plate. Since such an anti-resonance member does not reflect the sound wave propagating toward the anti-resonance member in a direction opposite to the propagation direction, but reflects in a different direction, as described above, alternating between the two wall surfaces. There is no reflection. In particular, the corrugated plate, the concavo-convex plate, and the curved plate are diffused by reflecting sound waves in a number of directions, so that the suppression effect is great. 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.
[0014]
Examples of the anti-resonance member having a function of attenuating sound waves include known sound absorbing materials such as fibrous porous materials such as glass wool and steel wool, and foamed porous materials such as foamed ceramic and urethane. In addition to the material, a perforated plate in which a large number of through holes are formed may be used. Such a resonance prevention member attenuates the sound wave propagating toward the resonance prevention member on the surface or inside thereof, thereby suppressing the generation of standing waves and preventing the generation of the noise. Here, the perforated plate attenuates the sound wave by becoming a resistance to the density wave and reducing the reflection surface of the sound wave. Therefore, the perforated plate is provided in a state of keeping a predetermined distance without being in close contact with the wall surface in the gas chamber.
[0015]
Furthermore, examples of the resonance preventing member having a function of diffusing sound waves and a function of attenuating sound waves include a corrugated porous plate and a concavo-convex porous plate. Here, the resonance preventing member having each function includes a member having the same function or a combination of members having different functions. The resonance preventing member includes a configuration in which the resonance preventing member itself constitutes the wall surface of the gas chamber, in addition to a member provided on the wall surface constituting the gas chamber.
[0016]
Moreover, in this invention, the structure which has arrange | positioned the said sound-absorbing material in the back surface side of the said perforated panel is included as the said resonance prevention member. In this configuration, the perforated plate and the sound absorbing material exhibit the effect of reducing the resonance noise, and the porous plate functions as a holding member that holds the sound absorbing material in a predetermined position.
[0017]
As described above, the sound generated in the duct depends on the speed of the combustion air sent from the blower (wind speed), and the change in this speed generates sound in various frequency bands. Noises of various frequencies can be reduced by diffusing or attenuating sound waves by the prevention member.
[0018]
【Example】
Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. First, a first embodiment of the present invention will be described. 1 is a cross-sectional explanatory view showing the configuration of the first embodiment of the present invention, FIG. 2 is a cross-sectional explanatory view taken along the line II-II in FIG. 1, and FIG. It is explanatory drawing of the cross section along a III line.
[0019]
The premixed gas burner according to the present invention includes a burner element 2 that ejects and burns premixed gas on the downstream side of a cylindrical duct 1 that constitutes a flow path for combustion air. A blower (not shown) is connected to the upstream side of the duct 1 as air supply means, and combustion air is supplied by this blower.
[0020]
In the middle of the duct 1, a mixing unit 3 having an ejector function is provided. That is, a similar throttle member 4 paired with a predetermined position of the duct 1 is arranged so as to face, and the mixing portion 3 is formed at the center. In the first embodiment, the width of the throttle member 4 is substantially the same as the inner width of the duct 1, and the throttle member 4 facing the duct 1 has an upstream side in the flow direction of combustion air. Thus, the nozzle part 5 in which the flow path cross-sectional area gradually decreases, the throat part 6 having substantially the same flow path cross-sectional area 6, and the diffuser part 7 in which the flow path cross-sectional area gradually increases are configured. A gas chamber 8 is formed outside the throttle member 4, that is, in a space between the inner wall of the duct 1. In the throat portion 6 corresponding to the mixing portion 3, a large number of small holes are formed as fuel gas ejection holes 9.
[0021]
A fuel gas supply pipe 10 for supplying fuel gas is connected to the gas chamber 8 from the outside of the duct 1. When connecting the fuel gas supply pipe 10, it may be from any direction such as the left-right direction and the front-rear direction of the duct 1, but in this first embodiment, as shown in FIG. A through hole 11 communicating with the gas chamber 8 is formed on one side wall surface, a branch pipe 12 is connected so as to cover the through hole 11, and the fuel gas supply pipe 10 is connected to the branch pipe 12. is there.
[0022]
According to the above configuration, when the combustion air supplied from the upstream end of the duct 1 passes through the mixing unit 3, the flow is once throttled in the nozzle unit 5 and then passes through the throat unit 6. In the diffuser section 7, it is enlarged. Therefore, the combustion air is a high-speed air flow in the throat portion 6, and in the middle of the throat portion 6, the fuel gas supply pipe 10 passes through the gas chamber 8 and the fuel gas ejection hole 9. The supplied fuel gas is effectively sucked into the throat portion 6. In the diffuser section 7, after being efficiently mixed with combustion air, it is supplied as premixed gas to the burner element 2 at the downstream end of the duct 1.
[0023]
That is, in the premixed gas burner, the mixing portion 3 having the function of an ejector is provided at a predetermined position in the duct 1, and the fuel gas injection hole 9 is opened in the mixing portion 3. The high-speed air flow can promote the mixing of the combustion air and the fuel gas, thereby generating a uniform premixed gas. Furthermore, 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 the pipe cost is reduced. Can be reduced.
[0024]
Now, the configuration of the gas chamber 8 in such a premixed gas burner 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 provided. Is partitioned as the gas chamber 8. In the gas chamber 8, a resonance preventing member 20 is provided on the wall surface facing the throat portion 6. The resonance preventing member 20 in the first embodiment is composed of a perforated plate 21 having many small holes such as so-called punching metal, and a sound absorbing material 22 such as glass wool.
[0025]
The perforated plate 21 is disposed in the gas chamber 8 between the wall surface constituting the throat portion 6 and the wall surface 1 a constituting the duct 1. The perforated plate 21 acts as a resistance to sound waves (air density waves) propagating between the wall surface constituting the throat portion 6 and the wall surface 1a constituting the duct 1, and has a small area for reflecting sound waves. The sound wave is attenuated by being reduced by the holes. On the other hand, the sound absorbing material 22 is filled between the back side of the perforated plate 21 and the wall surface 1 a of the duct 1. In this configuration, the porous plate 21 also functions as a holding member for holding the sound absorbing material 22 at a fixed position on the wall surface 1a.
[0026]
In the above configuration, when the combustion air supplied into the duct 1 passes through the throat portion 6, a resonance noise is generated in the gas chamber 8. This resonance noise is mainly generated in the throat portion. This is due to the sound transmitted from the fuel gas ejection hole 9 provided in 6 to the inside of the gas chamber 8. That is, sound (sound wave) is a dense 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 that is an integral multiple of this frequency are determined. A standing wave is generated, and this standing wave becomes a resonance sound. However, in the premixed gas burner, the resonance preventing member 20 causes the sound wave propagating in the gas chamber 8, particularly the sound wave propagating between the wall surface constituting the throat portion 6 and the wall surface 1 a in the duct 1. Is attenuated in the middle thereof to prevent resonance in the gas chamber 8. In other words, the generation of the standing wave can be suppressed by preventing the propagation of the sound wave, thereby preventing the generation of the resonance sound.
[0027]
In the premixed gas burner configured as described above, the resonance preventing member 20 is a combination of the perforated plate 21 having a function of attenuating sound waves and the sound absorbing material 22 . Further, the first embodiment is an embodiment of the resonance preventing member 20 for attenuating the sound wave. The resonance preventing member 20 includes a member having a function of diffusing the sound wave, and will be described below. To do. Here, FIG. 4 is a sectional explanatory view showing the configuration of the second embodiment of the present invention, FIG. 5 is a sectional explanatory view showing the configuration of the third embodiment of the present invention, and FIG. FIG. 7 is a cross-sectional explanatory view showing the configuration of the fourth embodiment of the invention, and FIG. 7 is a cross-sectional explanatory view showing the configuration of the fifth embodiment of the present invention. In each of the following embodiments, the gas chamber 8 is configured by providing a partition wall 13 having a substantially U-shaped cross section on the back surface side of the wall surface constituting the throat portion 6.
[0028]
First, the second embodiment shown in FIG. 4 includes a corrugated diffuser plate 23 as the resonance preventing member 20. In the gas chamber 8, the diffusion plate 23 is attached along substantially the entire surface of the wall surface 13 a facing the fuel gas injection hole 9 among the wall surfaces of the partition wall 13. Here, the arrangement procedure of the curved portion of the diffusion plate 23 is orthogonal to the air flow direction of the combustion air even if the ridge line direction of the corrugated plate is arranged along the flow direction of the combustion air in the duct 1. You may arrange in the direction to do.
[0029]
In this second embodiment, since the resonance preventing member 20 is the corrugated diffuser plate 23, the sound wave propagating toward the diffuser plate 23 is not reflected in the direction opposite to the propagation direction, and many As described above, the light is not reflected alternately between the two wall surfaces. That is, unlike the flat plate, the diffuser plate 23 diffuses the sound wave by reflecting it in a number of different directions, so that the reflected sound wave is attenuated. Here, the diffusion plate 23 may be a perforated plate or a corrugated perforated plate in addition to the corrugated plate shape. That is, as described above, the corrugated plate mainly diffuses sound waves on the surface thereof, and the perforated plate exerts the above-described effect mainly by reducing the reflectivity of sound waves itself. Further, the diffuser plate 23 may have a concavo-convex plate shape in which a large number of convex portions, concave portions, or both are formed on the surface in addition to the corrugated plate and the porous plate.
[0030]
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 formed of an inclined plate. That is, among the wall surfaces in the gas chamber 8, the wall surfaces facing each other are formed to be inclined at a predetermined angle, and the parallel wall surfaces are eliminated. With this configuration, there is no portion where the sound wave is repeatedly reflected in the opposite direction by 180 degrees, and the sound wave is reflected in various directions, so that generation of a standing wave can be suppressed.
[0031]
In this third embodiment, the opposing wall surfaces are given a predetermined angle to eliminate the parallel wall surfaces, thereby preventing the occurrence of standing waves. In that respect, in addition to the corrugated diffuser plate 23, the uneven diffuser plate has a similar function. Here, in FIG. 5, two opposing wall surfaces positioned in a direction perpendicular to the paper surface may be inclined with each other, and the corrugated diffuser plate 23 is disposed as in the second embodiment. Alternatively, a porous sound absorbing material 22 such as glass wool as described above may be disposed on this surface.
[0032]
Next, in the fourth embodiment shown in FIG. 6, at least the surface facing the throat portion 6 among the wall surfaces constituting the gas chamber 8 is formed into a curved shape, thereby eliminating the parallel wall surfaces. As in the third embodiment, the generation of standing waves is prevented. That is, in this fourth embodiment, the curved opposing surface eliminates the location where the sound wave is reflected in the opposite direction by 180 degrees, and the sound wave is reflected in the diffusing direction, so that the generation of standing waves is suppressed. Here, the formation of such a curved opposing surface can be easily configured, for example, by using a member obtained by appropriately cutting a pipe-shaped member along the axial direction.
[0033]
Further, in the fifth embodiment shown in FIG. 7, a partition wall 13 having a U-shaped cross section is constituted by the diffusion plate 23 similar to the second embodiment. In the fifth embodiment, since the partition wall 13 in the gas chamber 8 is constituted 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.
[0034]
Here, the resonance preventing member 20 having the above-described functions may be configured by combining those having the same function or those having different functions. That is, the resonance reducing effect is enhanced by arranging the diffusion plate 23 on the inclined facing surface or the curved facing surface. In this case, the diffusion plate 23 is a corrugated plate-like or uneven diffusion plate or the like, as described above. Furthermore, by disposing the sound absorbing material 22 on the surface facing the throat portion 6 in the gas chamber 8, reflection of standing waves is prevented and the intensity of sound waves reflected toward the facing surface is attenuated. Prevents resonance.
[0035]
In the first to fifth embodiments described above, the anti-resonance member 20 is provided at a location facing the wall surface constituting the throat portion 6, and in the third to fifth embodiments, at the location. It is also provided on the adjacent wall. That is, in the present invention, the resonance preventing member 20 may be provided on one of the wall surfaces constituting the gas chamber 8 or may be provided on all the wall surfaces. It may be provided on at least one of the wall surfaces. Specifically, when emphasis is placed on performance, the resonance prevention member 20 is provided on all wall surfaces in the gas chamber 8 to reliably prevent the generation of resonance noise. Further, when importance is attached to the cost, for example, when a strong standing wave is generated between the wall surface constituting the throat portion 6 and the opposite wall surface, thereby generating a resonance sound, By providing the resonance preventing member 20 on at least one of the wall surfaces, it is possible to achieve a significant reduction in resonance noise at a minimum cost.
[0036]
Here, the sound generated in the duct 1 depends on the speed of the combustion air sent from the blower. For example, when the premixed gas burner is for a boiler, a sound in various frequency bands is generated due to a change in speed at the time of boiler start-up or combustion transition. By diffusing or attenuating, the above-mentioned effect of reducing noise is exhibited at various frequencies.
[0037]
【The invention's effect】
According to the invention, by providing a resonance preventing member in the gas chamber, it is possible to suppress the occurrence of a standing wave in the gas chamber, that the combustion air increases the velocity when passing through the throat portion It is possible to prevent the occurrence of noise. Further, according to the present invention, since the generation of the standing wave is suppressed by the resonance preventing member, even if the noise frequency band changes according to the flow velocity of the combustion air in the duct, the frequency band The reduction effect can be exhibited regardless of whether or not. Furthermore, the perforated plate and the sound absorbing material can exhibit the effect of reducing the resonance noise, and the porous plate can function as a holding member that holds the sound absorbing material in a predetermined position.
[Brief description of the drawings]
FIG. 1 is an explanatory cross-sectional view showing a configuration of a first embodiment of the present invention.
FIG. 2 is an explanatory diagram of a cross section taken along the line II-II in FIG.
3 is an explanatory diagram of a cross section taken along line III-III in FIG. 2;
FIG. 4 is an explanatory cross-sectional view showing a configuration of a second embodiment of the present invention.
FIG. 5 is an explanatory cross-sectional view showing the configuration of a third embodiment of the present invention.
FIG. 6 is an explanatory cross-sectional view showing the configuration of a fourth embodiment of the present invention.
FIG. 7 is an explanatory cross-sectional view showing a configuration of a fifth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Duct 2 Burner element 3 Mixing part 4 Throttling 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 Porous plate 22 Sound absorbing material

Claims (1)

Combustion air is supplied from the upstream side, the duct 1 having the burner element 2 attached to the downstream side, and the fuel gas is supplied from the fuel gas supply pipe 10. The mixing unit 3 includes a nozzle unit 5, a throat unit 6, and a diffuser unit 7. A fuel gas ejection hole 9 is formed in the throat unit 6, and the throat unit 6 of the outward fuel gas injection holes 9 and the fuel gas supply pipe 10 and the gas chamber 8 which communicates provided, because the combustion air to prevent the noise generated when passing through the throat portion 6, the gas chamber 8 is provided with a resonance preventing member 20 having a function of attenuating sound waves. The resonance preventing member 20 includes a perforated plate 21 and a sound absorbing material 22, and is provided between the perforated plate 21 and the wall surface in the gas chamber 8. Premix gas burner, characterized in that a serial sound absorbing material 22.

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