JPH0792219B2 - Combustion noise reduction device for hot water generator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion noise reduction device for a hot water generator, and more particularly to a low frequency band generated by the combustion of a hot water generator composed of a furnace tube type or a tube smoke tube type combustion furnace using a gun type burner. The present invention relates to a combustion noise reduction device that reduces the noise of a hot water generator by a resonance damping effect that resonates the noise of the above.

[0002]

2. Description of the Related Art It is known that a hot water generator uses a combustion tube type combustion furnace shown in FIG. 10 (A) or a tube smoke tube type combustion furnace shown in FIGS. 10 (B) and 10 (C). In the furnace-cylinder combustion furnace of FIG. 10 (A), an air intake port is provided in the lower portion of the vertical furnace cylinder 41.
The combustion gas 45 generated when the gun-type burner 42 in which the 43 is formed forms the flame 44, rises while rotating around the heat exchange section 46, as shown schematically with arrows, and exits from the combustion gas outlet. It is discharged from 47.

In the vertical furnace tube smoke tube type combustion furnace shown in FIG. 10 (B), the smoke tube 49 is arranged above the vertical furnace tube 48, and the combustion gas 45 rises in the furnace tube 48. Then smoke pipe 49
It rises inside and is discharged from the combustion gas outlet 47 to the outside. In addition, in FIG. 10 , the parts denoted by the same reference numerals in FIGS. 10A, 10B, and 10C are the same parts as already illustrated.

In the combustion furnace shown in FIG. 10 (C), the burner 42 is disposed above the furnace barrel 50 and the flame 44 is ejected downward.
The smoke tube 49 is configured to be independent of the furnace tube 50, and the combustion gas 45 flows laterally along the communication passage 51 and then upward in the smoke tube 49 into the smoke chamber 52, and then the combustion gas. Exit 47
Is discharged from the outside.

The above-mentioned gun type burner is for burning oil or gas, and generally has the structure shown in FIG. 11 , and the air 53 taken in from the air suction port 43 is arranged in front of the nozzle 54. Flow toward a diffuser (flame holding plate) 55 and ignite with an ignition electrode (not shown) to produce flame 44 and combustion gas 45. At this time, when the fuel (liquid, gas) injected from the nozzle 54 and the combustion air 53 are rapidly mixed and turbulently combusted, a pulsation and fluctuation of the local pressure generate a roaring combustion noise.

In the combustion shown in FIG. 11 , a series of air such as a furnace tube (also called a combustion chamber) and a smoke tube (heat exchange section),
Passing path such as combustion gas to form a resonance tube 58 of Helmholtz shown in FIG. That is, a resonance tube having both ends of the burner air suction port 56 and the exhaust gas outlet 57 is formed, and the fundamental resonance wavelength λ = 2L. The present applicant manufactures and sells a hot water generator 11 using a gun type burner shown in a partially cutaway side sectional view of FIG. 5 , and if only the main part of the figure is explained, 12 is a burner, 13 Is a flame, 14 is a combustion furnace (also called a combustion chamber), 14a is a connecting passage, 15 is a smoke pipe,
16 is a straightening cylinder, 17 is a hot water storage tank, 18 is a smoke chamber, 19 is a chimney, 20 is a hot water outlet, and 21 is an exhaust silencer. When combustion is started by the burner 12, a flame 13 is created in the combustion furnace 14, and the combustion gas generated at that time passes through the communication path 14a and makes a U-turn to enter the smoke pipe 15 in which the rectifying tube 16 is arranged, and the smoke is generated. It makes a U-turn again through the chamber 18 and is discharged to the chimney 19. With this structure, the water in the hot water storage tank 17 is heated and supplied from the hot water outlet 20 to a predetermined location.

[0007]

Although the above-described exhaust silencer 21 has a predetermined noise reduction effect, noise in the low frequency band (sound in the low frequency range) is not sufficiently reduced, and after the noise of the night world disappears. It turned out to be a continuous low rustling noise. The inventor of the present application tested noise generated during operation of the hot water generator shown in FIG. 5 at a measurement point 22 about 20 cm away to the right of the chimney 19. This test is hereinafter referred to as test A-1. To do. The results are shown in the diagram of FIG. 6 , in which the horizontal axis represents Hertz (Hz) and the vertical axis represents sound intensity in decibels (dB). The test conditions included an exhaust silencer, and the smoke chamber was subjected to sound absorption processing. The test was conducted on November 7, 1991. From the figure, 3
Higher frequencies between 1.5 and 200 Hertz are perceived. Note that FIG. 7 prior to the hot water generator, i.e. shows the results of testing at the measurement point 23 in FIG. 5, this test test A
Call it -2. Measurement point 23 is the ground surface according to JIS standard
31 and 1m from the front of the hot water generator 11, respectively.

[0008] The test described above, with reference to FIG. 13,
Microphone placed at measurement point 22 20 cm away from chimney 19
34 captured sounds were recorded by the recorder 35 and analyzed by the analyzer 36. In FIG. 13 , reference numeral 32 indicates the air intake, and the arrow indicates the front. The other measuring point 23 was set at a height of 1 m from the front of the hot water generator 11 and 1 m from the ground surface 31 according to the JIS standard. The microphone 34 is NA-20 type manufactured by Rion Co., Ltd. in Kokubunji, Tokyo, normal noise type, the recorder 35 is the level coder LR-04 type manufactured by Rion Co., Ltd., recording type, and the analyzer 36 is Rion Co., Ltd. Analyzer SA-24 type, 1
A / 3-1 / 1 octave real time analyzer was used. The combustion state was adjusted to O ₂ = 5.6% and the amount of fuel oil = 12.4 (liter / hour). The test date was November 7, 1991.

SUMMARY OF THE INVENTION An object of the present invention is to provide a device for reducing low frequency noise generated from a hot water generator using a gun type burner.

[0010]

The present invention provides a hot water generator comprising a gun type burner for burning a liquid or gas fuel and a furnace tube type or furnace tube smoke tube type combustion furnace.
A combustion noise reduction device for a hot water generator, characterized in that a part of a smoke chamber provided at an outlet of combustion gas of the combustion furnace is a resonance chamber, and the resonance chamber is partitioned by a flat plate having a hole to resonate. A combustion noise reduction device for a hot water generator, which reduces combustion noise in a specific frequency band by a damping effect.

[0011]

That is, according to the present invention, the resonance chamber 24 is provided at the combustion gas outlet of the smoke pipe 15 so that the low frequency sound generated by the combustion is resonantly attenuated. A flat plate facing the smoke tube 15 of the resonance chamber 24
Holes 26 are formed in 28. The diameter of the hole 26 is such that
It is set so that the combustion noise coming out of the smoke pipe 15 resonates and is attenuated at the necked part connected to. The resonance sound is resonantly attenuated in the air cavity portion 30 and is further absorbed by the sound absorbing material forming the sound absorbing portion 25, thus reducing the low frequency sound generated by the combustion gas.

[0012]

The present invention will be described in detail below with reference to the illustrated embodiments. The inventor of the present application, in a survey on silencing of low-frequency noise, supervised by the Ministry of International Trade and Industry, Bureau of Environmental Pollution, "Techniques and Laws for Prevention of Pollution, 2nd Edition, Noise Regulations," Edition 137, Resonance Structure We focused on the body and the resonant structure on page 139. Ibid. Pp. 139-140 and 139
Referring to the page of FIG. 4.48 (Figure 8 of the present application drawings), 8
Also, in the case of sound waves having a large wavelength, the air in the elongated neck portion moves up and down as a unit, while the air in the air cavity acts as a spring that supports the mass of the neck portion due to the elasticity of the volume. The natural frequency in such a case is

[Equation 1] It is represented by. Where C is the speed of sound (m / s), S is the cross-sectional area of the neck (m
² ), h ′ is the effective length of the neck (m). If the neck cross section is circular and the diameter is φ (m), h ′ = h + 0.8φ (4.52), where h is the actual length of the neck. Becomes V is the volume (m ³ ) of the air cavity.

Further, referring to FIG. 4.49 (FIG. 9 of the accompanying drawings) of the above-mentioned page 140, FIG. 9 shows that an air layer is provided behind a perforated plate in which circular holes are arranged at equal intervals. The case
Focusing on the minimum unit separated by the dotted line, it can be understood that this corresponds to (a) in Figure 4.48 of the forward tilt. Therefore, the natural frequency in this case is

[Equation 2] Can be written as Where t is the plate thickness (m), φ is the diameter of the perforated circle (m), L is the depth of the air layer (m), P is the aperture ratio of the perforated plate, and P = πφ ² / 4D ^{Is 2} . By contrast with the formula (1), S = (1/4) πφ ² , h ′ = t + 0.8φ, V = D ²
The relationship is L. The size of the hole and the like are set with the resonance attenuation frequency of f in equations (1) and (2).

In the present invention, referring to the above, as shown in FIG. 1, the combustion gas outlet portion of the smoke pipe 15 (see FIG.
The resonance chamber 24 is provided in the portion shown in 5 where the smoke chamber 18 is provided)
Inside thereof, a sound absorbing portion 25 shown by double hatching in FIG. 2 is arranged. Incidentally, FIG. 1 is different only in that the resonance chamber 24 is provided with 5, other portions configuration as that shown in FIG. 5, the same both functions. In this embodiment, the sound absorbing part 25
Is made of rock board, but the material is not limited to this and other sound absorbing materials may be used. In the present invention, at the outlet of the combustion gas, the resonance chamber 24 is used to resonance-attenuate the low range noise generated by the combustion gas, and the sound absorbing section 25 absorbs the sound to reduce the low range noise emitted to the outside. is there.

Details of the resonance chamber 24 are shown in the plan view of FIG. 2 (A) and the front sectional view of FIG. 2 (B), and the reference numeral 15 indicates a smoke tube as in FIGS. 1 and 5. In FIG. 1, two smoke tubes 15 are arranged in the direction perpendicular to the plane of the drawing, and only the smoke tube 15 in the front is shown, but FIG. 2B is a cross-sectional view taken along the line II-II in FIG. Two smoke tubes 15 are shown. Figure 2
In FIG. 2A , the hole 26 is a hole having a diameter of 110 mm formed according to the first pattern created by the present inventor .
Are those shown (B), the addition holes 27 are formed in the pipe 27a with a diameter of 60.5mm formed in a second pattern by the present inventor, the arrangement of the pipes 27a and the hole 27 is 2 in (C) Shown in cross-section. That is, FIG. 2 (A)
Shows holes 26 and 27 together, but in reality
As described above, when the first pattern is used for the flat plate 28,
If only the holes 26 are used, and the second pattern is used
Only the holes 27 are formed in the holes. The hole 26 is formed in the flat plate 28 of the sound absorbing portion 25 facing the smoke pipe 15, and the diameter of the hole 26 is the sound absorbing portion , that is, the cavity 30 of the resonance chamber 24 and the hole 2.
It is set using the above formula so that the low frequency sound 29 emitted from the smoke pipe 15 resonates at the neck portion where 6 communicates with as shown by the arrow 29a. The same applies to the hole 27.

In FIG. 2, reference numeral 24a is a resonance chamber outer frame, and 24
b is the lid of the resonance chamber, and the flat plate 28 was formed to have a thickness of 3.2 mm. The resonance chamber 24 has a depth D as shown in FIG.
Approximately 330 mm, width W approximately 720 mm, height H shown in FIG. 2B is approximately 250 mm, and the volume of the resonance chamber 24 is approximately 330 × 720.
× 250 mm ³ . The sound absorbing part 25 with double diagonal lines is about
It had a thickness of 50 mm.

The outer wall of the resonance chamber 24 and the flat plate 28 are made of a resonance material such as an iron plate, but other materials may be used. The distance between the top of the smoke tube 15 and the flat plate 28 of the resonance chamber 24 was set to 170 mm. After the assembly was completed, a heat resistant material (eg heat resistant Tezuzole) was applied. Referring to FIG. 2 (B), the low frequency sound 29, which is schematically shown by the hollow arrow generated by the combustion, resonates at the neck of the cavity 30 created by the hole 26 as shown by the hollow arrow 29a. The sound is attenuated and further absorbed by the sound absorbing unit 25.

The results of the tests of the embodiment shown in FIGS. 1 and 2A and 2B will be explained.
It was conducted on November 7. Measurement tool used for the test, the measurement method is the same as that shown in FIG. 13. An exhaust silencer was used, and a resonance chamber with an improved part of the smoke chamber was used. If this test is called test B, the result is shown in FIG.
7 is shown in a diagram similar to FIG. 3 and FIG. 4 , where FIG.
22 shows the test result, and FIG. 4 shows the test result at the measuring point 23. The vertical and horizontal scales in FIGS. 3 and 4 are shown in FIGS. 6 and 7.
Is the same as in. A comparison of the test A-1 and test B-1 results is shown in Table 1.

[Table 1] (In this table, “All Pass” is used to measure the level of all components in the frequency analysis (whole range level), and “F scale” is used to measure sound pressure level using F scale (flat characteristic)). The lowest value in Table 1 shows, by a negative dB value, how much noise the test B-1 reduced compared to the test A-1. In Table 1, 80Hz, 100Hz, 12
It can be observed that the sound at 5Hz and 160Hz has been significantly reduced, but it is understood that the desired noise reduction can be achieved by appropriately changing the dimensions of the resonance chamber and the size of the holes. As for the actual feeling of the noise test, in the case of test A-1, low noise was continuously heard, whereas in test B-1,
I felt that the low noise was trapped inside, and the sound heard outside was much lower.

[0019]

As described above, according to the present invention,
The low-range noise generated by the hot water generator using the gun type burner is significantly reduced, and as a result, the hot water generator can be used without causing noise pollution in the neighborhood even at night when the noise of the world is reduced. It was confirmed that there was not.
The materials of the resonance chamber and the sound absorbing part, the diameter of the holes, etc. are not limited to the materials and dimensions shown, but can be set appropriately.

[Brief description of drawings]

FIG. 1 is a partially cutaway side sectional view of a hot water generator according to an embodiment of the present invention.

FIG. 2 is a diagram of a resonance chamber provided in the hot water generator shown in FIG.
(A) is a plan view, (B) is a sectional view taken along the line II-II of FIG.
(C) is a sectional view of another example.

FIG. 3 is a diagram showing a noise test result of an example of the present invention.

FIG. 4 is a diagram showing a noise test result of an example of the present invention.
It

FIG. 5 is a partially cutaway side sectional view of a hot water generator using a conventional gun type burner.

FIG. 6 is a diagram showing a noise test result of a conventional hot water generator.

[Figure 7] Diagram showing noise test results of conventional hot water generator
Is.

FIG. 8 is a cross-sectional view of a resonance structure.

FIG. 9 is a view showing a cross section and a plane of another resonance structure.

FIG. 10 is a schematic cross-sectional view of a hot water generator, in which (A) is a tube-type combustion furnace, and (B) and (C) are tube-flue tube combustion furnaces.

FIG. 11 is a diagram illustrating a gun type burner.

FIG. 12 is a diagram illustrating a Helmholtz resonance tube.

FIG. 13 is a diagram showing a noise measuring method.

[Explanation of symbols]

 11 Hot water generator 12 Burner 13 Flame 14 Combustion furnace (combustion chamber) 14a Communication path 15 Smoke pipe 16 Straightening cylinder 17 Hot water tank 18 Smoke chamber 19 Chimney 20 Hot water outlet 21 Exhaust silencer 22,23 Measuring point 24 Resonance chamber 24a Resonance chamber outer frame 24b Resonance chamber lid 25 Sound absorption part 26,27 hole 27a Pipe 28 Flat plate 29 Low frequency sound 30 Air cavity part 31 Ground surface 32 Air inlet 34 Microphone 35 Recorder 36 Analyzer 41 Furnace (combustion chamber) 42 Burner 43 Air intake Mouth 44 Flame 45 Combustion gas 46 Heat exchange section 47 Combustion gas outlet 48 Furnace tube 49 Smoke tube 50 Furnace tube 51 Communication passage 52 Smoke chamber 53 Air 54 Nozzle 55 Diffuser (fire plate) 56 Inlet 57 Outlet 58 Helmholtz resonance tube

Claims (2)

[Specification] [Claims] 1. A gun-type burner for burning liquid or gas fuel and a furnace tube type or furnace tube smoke tube type combustion furnace (1
In the hot water generator (11) composed of 4), the combustion furnace
Enter the smoke pipe (15) from (14), and go through the smoke chamber (18).
It is discharged to the chimney (19) through the exhaust silencer (21).
Above the smoke chamber (18) in the path of the combustion gas flow
In addition, a hollow sound absorbing part (25) closed to the outside is provided.
Low frequency where flame (13) is generated by providing resonance chamber (24)
The lower part of the resonance chamber (24) with resonance damping of several bands of noise
Is partitioned by a flat plate (28) with holes (26), and holes (2
The diameter of 6) is the same as that of the pores (30) and holes (2) of the resonance chamber (24).
Low frequency band that comes out of the smoke pipe (15) at the part where 6) communicates
Combustion noise reduction device for a water heater characterized by being set to a value that resonates with the noise (29) of the above . 2. A gun for burning liquid or gaseous fuel.
Type burner and tube type or tube tube combustion furnace (1
In the hot water generator (11) composed of 4), the smoke tube (15) enters the smoke chamber (18) from the combustion furnace (14).
Through the exhaust silencer (21) to the chimney (19)
In the path of the emitted combustion gas flow, the smoke chamber (18)
A hollow sound absorbing part (25) closed to the outside is arranged in the upper part.
A flame (13) is generated by providing the resonance chamber (24).
A low frequency noise is resonantly attenuated, and a pipe is provided on the flat plate (28) below the resonance chamber (24).
(27a) forms a hole (27), and the diameter of the pipe (27a) is the cavity of the resonance chamber (24).
Is the smoke pipe (15) at the part where the hole (27) communicates with (30)?
Set to a value that resonates with the low frequency noise (29) emitted from the
Combustion noise reduction equipment for hot water generators
Place