JP3784193B2 - Industrial furnace exhaust noise suppression device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an industrial furnace exhaust noise suppression device for reducing exhaust noise generated from a supply / exhaust blower attached to an industrial furnace.
[0002]
[Prior art]
Industrial furnaces usually require large amounts of air for combustion. A supply / exhaust blower is used to supply combustion air into an industrial furnace and exhaust the exhaust gas after combustion to the outside. Is generated. For this reason, there are cases where the installation location of the industrial furnace is restricted such that it cannot be installed in a place close to a house.
[0003]
Further, in the high-temperature preheated air combustion industrial furnace, the exhaust temperature is 200 ° C. or higher, and the flow rate is higher than that of a normal industrial furnace. In general, when the flow velocity is V and the nozzle diameter is d, the sound peak is expressed by f _peak = S ₀ V / d, where f _peak is 0.1 or 0.2 in terms of the Strauhal number. Therefore, the higher the flow velocity and the smaller the nozzle diameter, the higher the frequency, and in such a high-temperature preheated air combustion industrial furnace, the noise in the high sound range tends to be larger than that in the conventional industrial furnace.
[0004]
In conventional industrial furnaces, no special measures have been taken to reduce the exhaust noise generated from the supply / exhaust blower, and even if this is done, a vibration-proof rubber is placed between the installation base and the supply / exhaust blower. Absorbing vibrations and noise at frequencies, attaching an extension pipe to the exhaust pipe side of the supply / exhaust blower, and adjusting its length to a length that does not resonate, etc. In essence, an industrial furnace is installed in a place isolated from the residential area to prevent noise.
[0005]
[Problems to be solved by the invention]
It is not an essential solution to select an industrial furnace installation location as a noise countermeasure, and the flexibility of the installation location is also limited. Soundproofing and vibration-proofing measures using anti-vibration rubber are effective to some extent for low-frequency noise, but are not effective as countermeasures for high-frequency noise generated from a high-temperature preheated air combustion industrial furnace as described above. In addition, noise caused by resonance causes the pipe connected to the blower air supply / exhaust port to vibrate, and other portions resonate to generate noise.
[0006]
A method using an extension tube having a length that does not resonate is effective for high-frequency noise, but it cannot reduce low-frequency noise of about several tens of Hz by itself. Furthermore, the length of the extension pipe is determined by cut-and-try and requires complicated work. In addition, it is not preferable from the viewpoint of scenery that such an extension pipe rises in a place close to a residential area.
[0007]
An object of the present invention is to provide an improved industrial furnace exhaust noise suppression device for reducing noise from an air supply and exhaust blower attached to an industrial furnace, and more specifically, while being compact. Another object of the present invention is to provide an industrial furnace exhaust noise suppression device capable of greatly reducing the noise level from a low frequency to a high frequency by disposing the exhaust gas in an exhaust gas passage that guides the exhaust gas to the outside.
[0008]
[Means for Solving the Problems]
An industrial furnace exhaust noise suppression apparatus according to the present invention for solving the above-mentioned problems is provided with an exhaust gas inlet at one end in an exhaust gas passage for guiding exhaust from an air supply / exhaust blower attached to an industrial furnace to the outside. One exhaust gas flow path and a second exhaust gas flow path having an exhaust gas outlet at one end are arranged substantially in parallel, and the other end sides thereof are connected by a third exhaust gas flow path. Therefore, the first, second, and third exhaust gas passages are generally formed of a lead plate in which a material having a sound absorbing function is laminated on the inner surface, and In at least the first exhaust gas flow path and the second exhaust gas flow path, a plurality of shielding plates made of a material having a sound absorbing function are alternately arranged so as to exceed half of the horizontal width of the flow path. It is characterized by disposing an exhaust duct.
[0009]
According to the industrial furnace exhaust noise suppression apparatus, the exhaust from the exhaust port of the supply / exhaust blower attached to the industrial furnace is disposed in the first exhaust gas flow path in the exhaust duct having a substantially U shape as a whole. The exhaust gas flows in from the exhaust gas inlet disposed at one end, passes through the first exhaust gas flow path and the third exhaust gas flow path and enters the second exhaust gas flow path, or passes through the second exhaust gas flow path and passes through the second exhaust gas flow path. It is discharged out of the exhaust duct from an exhaust gas outlet attached to one end of the gas flow path.
[0010]
At least inside the first and second exhaust gas passages, the length is more than half of the lateral width of the passage and has a sound absorbing function which is a material such as glass wool, steel wool, and foamed resin material. A plurality of shielding plates made of material are alternately arranged, and the high-temperature and high-speed exhaust gas proceeds while changing the course in a zigzag manner while colliding with the shielding plates. As a result, the flow velocity decreases.
[0011]
Now, the total acoustic output P generated by the flow ejected from the opening of the area S at the velocity U is
It is expressed by the Lighthill parameter, P = μρC ⁻⁵ U ⁸ S, and μ is about 6 × 10 ⁻⁶ . When ρU ³ S is regarded as the energy inherent in the gas, the sound output is proportional to (U / C) ⁵ , and according to the present invention, the noise level of the airflow sound is effectively reduced by reducing the flow velocity. To reduce.
[0012]
Further, the exhaust duct has a substantially U-shape as a whole, and a long exhaust gas flow path is ensured while having a compact shape. The inner surface of the long exhaust gas flow path is covered with a member having a sound absorbing function such as glass wool, steel wool, and foamed resin material, and the exhaust gas passes through the long exhaust gas flow path. The noise level is further reduced by converting sound energy into heat energy mainly by a material having a sound absorbing function for middle and high frequency range noise.
[0013]
On the other hand, from acoustic theory, the theoretical attenuation amount R of the sound absorbing duct structure in the present invention can be written as R = KP / A. Here, P is the circumferential length of the cross section (m), A is the cross sectional area (m ³ ) of the outlet duct, and the noise is effectively attenuated by increasing the circumferential length of the cross section. When the sound absorbing material is lined on the inner surface of the duct, the sound absorption rate of the sound absorbing material tends to increase as the frequency increases as a function of frequency, so that the damping effect is large in the high sound range, but is small in the low sound range.
[0014]
In our experiments, high-temperature exhaust gas of 200 ° C or higher with a low air density and a high flow rate from a high-temperature preheated air-fired industrial furnace generates a large high-frequency noise, but this high-temperature exhaust gas is introduced into the exhaust duct. The noise level was reliably reduced by passing the U-shaped detour while colliding with the shielding plate.
[0015]
In addition, the outside of the exhaust gas flow path, that is, the outside of the sound absorbing material is covered with a lead plate having a large specific gravity, so that low-frequency vibrations are absorbed there, and low-frequency noise of about several tens of Hz is also reliably reduced. . Preferably, the outside of the lead plate is further covered with an iron plate through a sound absorbing material such as glass wool, steel wool, foamed resin material, so that the mid-low frequency noise is further absorbed, and the mid-low frequency range vibration is also To reduce.
[0016]
As described above, in the industrial furnace exhaust noise suppression device according to the present invention,
1. By alternately installing sound-absorbing material, the flow velocity is reduced by collision, reducing the noise in the mid-high range,
2. By alternately installing sound-absorbing materials, further reducing the noise effectively by making the U-shaped compact and lengthening the perimeter of the cross section,
3. For the low sound range, it is attenuated by increasing the thickness of the sound-absorbing material and changing the direction of flow by making it U-shaped.
4). For low-frequency noise caused by vibration, further suppress the use of a lead plate as a damping material.
As a result, high vibration and noise reduction effects can be achieved over a wide range from the high sound range to the low sound range. Therefore, the restriction of the installation location due to the noise of the industrial furnace is reduced, and it becomes possible to install an industrial furnace such as a high-temperature air combustion industrial furnace in a research facility close to a residential area.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of an industrial furnace exhaust noise suppression device according to the present invention will be described with reference to the drawings.
In the figure, reference numeral 1 denotes a part of a building that houses an industrial furnace (not shown). In the building 1, conventional air for sending combustion air into the industrial furnace and sucking and exhausting combustion exhaust gas is shown. A known air supply / exhaust blower 2 is installed, and an exhaust cylinder 3 of the air supply / exhaust blower 2 penetrates through the roof 4 of the building 1 and extends upward. In this example, the exhaust duct 10 according to the present invention is installed on the roof 4 of the building 1, but the contact between the roof 4 of the building 1 and the exhaust duct 10 is not limited. An anti-vibration rubber 17 is disposed in the portion.
[0018]
The exhaust duct 10 has a first exhaust gas flow path portion 10A into which one end of the exhaust cylinder 3 of the supply / exhaust blower 2 serving as an exhaust gas inlet is inserted at one end, and the first exhaust gas flow path portion 10A. The second exhaust gas flow path portion 10B having an exhaust pipe 11 having an inverted U-shape as an exhaust gas outlet at one end, and the first exhaust gas flow path portion 10A and the second The exhaust gas flow path portion 10B is connected to the other exhaust gas flow path portion 10C in a communicating state, and is substantially U-shaped as a whole.
[0019]
Exhaust gas from an industrial furnace (not shown) flows from the exhaust tube 3 of the supply / exhaust blower 10 to one end side of the first exhaust gas flow path portion 10A, from which the first exhaust gas flow path portion 10A, It passes through the third exhaust gas flow path portion 10C and the second exhaust gas flow path portion 10B, and is discharged out of the exhaust duct 10 from the exhaust pipe 11 attached to one end of the second exhaust gas flow path portion 10B. Is done.
[0020]
Four rounds (the left and right side walls, the ceiling, and the bottom surface) of the first, second, and third exhaust gas flow path portions are covered with a sound absorbing material 12 such as glass wool having a thickness of about 100 mm. A lead plate 13 having a thickness of about 5 mm is attached to the outside of the material 12. Further, an iron plate 14 is affixed to the lead plate 13 with a sound absorbing material (not shown) such as glass wool interposed therebetween.
[0021]
In the first exhaust gas passage portion 10A and the second exhaust gas passage portion 10B, a shielding plate 16 made of the same material as the sound absorbing material 12 is in a posture orthogonal to the flow direction of the exhaust gas, and A plurality of sheets are alternately arranged so as to exceed half of the lateral width of each flow path. That is, the vertical length of each shielding plate 16 is the length reaching from the ceiling to the bottom of the exhaust duct, and the horizontal width is about 2/3 of the horizontal width of the flow path in this example. Each shielding plate 16 has a thickness of about 50 mm.
[0022]
In the industrial furnace exhaust noise suppression apparatus including the exhaust duct 10 having the above-described configuration, the high-temperature and high-speed exhaust gas flowing from the exhaust cylinder 3 of the supply / exhaust blower 10 to the one end side of the first exhaust gas flow path portion 10A is , Impinges on the shielding plate 16 (16a) closest to the inflow port, changes its direction and flows along the shielding plate 16a, and then between the side edge of the shielding plate 16a and the side wall of the exhaust duct 10. It moves downstream through the gap.
The moved exhaust gas collides with the next shielding plate 16b provided extending from the side wall opposite to the shielding plate 16a, changes its direction there again, flows along the shielding plate 16b, and the shielding plate 16b. It passes through the gap between the side edge of the plate 16b and the other side wall and collides with the next shielding plate 16.
[0023]
Hereinafter, the exhaust gas repeats such a zigzag progression, reaches the inlet of the third exhaust gas flow path portion 10C while decreasing the flow velocity, passes through the inlet, and passes through the second exhaust gas flow path portion 10B. After colliding with the shielding plate 16 on the inlet side, the second exhaust gas passage portion 10B is moved while repeating the zigzag movement in the same manner as in the first exhaust gas passage portion 10A, and finally the exhaust pipe 11 is discharged out of the exhaust duct 10.
[0024]
In the exhaust duct 10, as described above, the high-temperature and high-speed exhaust gas collides with the shielding plate 16 and moves while changing the course in a zigzag manner. The noise level is effectively reduced. Moreover, the entire inner surface of the long U-shaped exhaust gas flow path is covered with the sound absorbing material 12, and noise in the middle and high frequencies is absorbed by the sound absorbing material 12 to further reduce the noise level. Further, the outside of the exhaust gas passage is covered with a lead plate 13 having a large specific gravity, and the outside of the lead plate 13 is further covered with an iron plate 14 via a sound absorbing material such as glass wool. Frequency vibrations are also absorbed there, and low-frequency noise of about several tens of Hz is reliably reduced.
Further, by providing the vibration isolating rubber 17 between the roof 4 of the building 1 and the exhaust duct 10, unnecessary vibration due to the vibration of the air supply / exhaust blower 2 disposed in the building 1 is transmitted to the exhaust duct 10. Is also prevented.
[0025]
In the experiments conducted by the present inventors, in the industrial furnace exhaust noise suppression apparatus formed as shown in the figure, the measured value at a point 1 m from the supply / exhaust blower 2 is the white noise of 42 dB. When it is passed, it is 62 dB, and when exhausted directly from the exhaust tube 3 of the air supply / exhaust blower 2, it is 82 dB, and a significant noise reduction effect of 20 dB has been confirmed. The effectiveness of was demonstrated.
In the illustrated example, the third exhaust gas passage portion 10C is not provided with a shielding plate. However, when the pressure loss due to the provision does not adversely affect the combustion of the industrial furnace, the shielding plate is naturally provided. It is done.
[0026]
【The invention's effect】
As described above, the industrial furnace exhaust noise suppression device according to the present invention has a high vibration and noise reduction effect in a wide range from a high sound range to a low sound range, while having a compact shape. Therefore, the restriction of the installation location due to the noise of the industrial furnace is reduced, and it becomes possible to install an industrial furnace such as a high-temperature air combustion industrial furnace in a research facility close to a residential area.
[Brief description of the drawings]
FIG. 1 is a partially cutaway perspective view showing an embodiment of an industrial furnace exhaust noise suppression apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Building, 2 ... Supply / exhaust blower, 3 ... Exhaust cylinder of supply / exhaust blower, 10 ... Exhaust duct, 12 ... Sound absorbing material, 13 ... Lead plate, 14 ... Iron plate, 16 ... Sound insulation plate, 17 ... Anti-vibration rubber, 10A ... 1st exhaust gas flow path, 10B ... 2nd exhaust gas flow path, 10C ... 3rd exhaust gas flow path

Claims (3)

In the exhaust gas passage that leads the exhaust from the supply and exhaust blower attached to the industrial furnace to the outside,
A first exhaust gas flow path having an exhaust gas inlet at one end and a second exhaust gas flow path having an exhaust gas outlet at one end are arranged substantially in parallel, and each of the other ends is a third side. A lead plate in which the first, second and third exhaust gas passages are laminated with a material having a sound absorbing function on the inner surface by being connected by the exhaust gas passages to form a substantially U-shape as a whole. And at least the first exhaust gas flow path and the second exhaust gas flow path have a shielding plate made of a material having a sound absorbing function exceeding half of the lateral width of the flow path. Exhaust ducts arranged in a staggered manner,
An industrial furnace exhaust noise suppression device characterized by comprising: The industrial furnace exhaust noise suppression device according to claim 1, wherein at least an exhaust duct in which the lead plate is further covered with an iron plate from the outside is disposed. The industrial furnace exhaust noise suppression device according to claim 1 or 2, wherein the material having a sound absorbing function is any one of glass wool, steel wool, foamed resin material, or a combination thereof.

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