JP2010156508A - Ground flare - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grand flare suppressed in low frequency vibration generated from a ground flare tower such as a chimney below a threshold level of the generation of the vibration of fittings by properly controlling the low frequency vibration, thereby prevented in the resonance and/or vibration of surrounding structures. <P>SOLUTION: In the ground flare 10 where flammable waste gas is burned by burners 11 disposed at a lower end of the chimney and a lower end of the chimney 20 and the circumference of the burners 11 are surrounded by a wind shield 40, low frequency noise acoustic pressure level of the ground flare tower comprising the chimney 20 and the windshield 40 is reduced by selecting at least one of changing the natural frequency generated from the ground flare tower, increasing the number of the ground flare towers, and implementing a device for absorbing low frequency vibration into the ground flare tower. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ground flare used for combustion treatment of combustible exhaust gas.

2. Description of the Related Art Conventionally, treatment apparatuses that perform combustion treatment of combustible gas are roughly classified into three types: an incinerator, an open flare stack, and a ground flare stack (ground flare).
Examples of the combustible gas that is combusted by such a processing apparatus include gas generated by gasifying coal at the initial startup of the plant in an integrated coal gasification combined cycle (IGCC). It is a combustible exhaust gas that is unsuitable for gas turbine fuel. The coal gasification combined power generation facility is a facility that generates power by gasifying coal serving as a fuel, operating a gas turbine, and using the driving force of the gas turbine and the exhaust heat of the gas turbine.

The incinerator (see FIG. 24) is an incinerator body 1 formed of a refractory or the like and an air blower 2 is installed to combust a combustible gas. In this case, there is a problem that the cost of the refractory for molding the incinerator main body 1 and the cost of the air blower 2 are high. In addition, the code | symbol 3 in a figure is a burner, 4 is a chimney.
The open flare stack (see FIG. 25) is a device that ejects fuel into the atmosphere and burns combustible gas using an ignition device. Usually, the fuel outlet is arranged at a high position of the flare stack body 5. Since the combustion air is supplied by natural intake air from the surroundings, an air blowing device is unnecessary and the cost is low. However, since the flame is in an exposed state, it has been pointed out that there are fires caused by radiation to the surroundings, noise due to the combustion noise of the flame, and landscape incongruity due to the fact that the flame is visible.

  For example, as shown in FIG. 26, the ground flare 6 has a structure in which the lower end of the chimney 7 is opened and one or more burners 8 for combustible gas combustion are installed at the lower end of the chimney 7. In this case, since the chimney 7 and the windshield 9 are required, the cost is higher than that of the open flare stack. However, the ground flare 6 has the merit that the flame is surrounded by the windshield 9 and cannot be seen from the outside, and the combustion noise is reduced by the chimney.

As a conventional technique for reducing noise derived from a chimney, there is one in which a sound absorbing member is installed at an internal position of the chimney. (For example, see Patent Document 1)
Further, in the ground flare stack, a configuration is disclosed in which a noise shielding member surrounding the combustion chamber is disposed in a sound absorbing relationship with respect to the air flow sent into the combustion chamber. (For example, see Patent Document 2)
In addition, a noise canceling device is disclosed in which noise generated in a flue for forcibly exhausting combustion gas is silenced by canceling by dynamic silencing. (For example, see Patent Document 3)
Japanese Patent Publication No.58-2331 JP 54-45838 A Japanese Patent No. 2629410

By the way, in the above-mentioned conventional ground flare 6, there is a problem that surrounding objects resonate and vibrate due to low-frequency vibration generated from the chimney 7.
As conventional low-frequency vibration countermeasures in the ground flare 6, it is known to reduce the amount of air, change the burner flow velocity, and change the number of burners with the aim of lengthening the flame. However, such conventional countermeasures against low-frequency vibration have a problem that an unburned portion increases due to deterioration of combustibility and that a flame blows out from the upper portion of the stack due to a longer flame.
Further, as a measure for reducing the generated sound pressure by unevenly arranging the levels of the plurality of burners 3 and making the flame surface as a vibration source non-uniform, the burner 8 disposed on the upper side is provided with a lower burner. There is a defect that damages in contact with the flame.
Further, there are a method of limiting the chemical heat amount of the gas to be processed by the ground flare 6 and a method of operating only during the daytime when the noise standard is moderate. However, these are uneconomical because they limit the operation of the plant.

From such a background, by preventing resonance between the low frequency frequency of the ground flare tower and the natural frequency of the burner combustion and / or converting the vibration energy into heat energy, the sound pressure level of the low frequency noise is reduced. It is desired to suppress the increase and to reduce the low frequency vibration generated from the ground flare so as to be less than the vibration generation limit of the joinery.
The present invention has been made in view of the above circumstances, and the object of the present invention is to appropriately adjust low frequency vibration generated from a ground flare tower body such as a chimney to keep it below the vibration generation limit of joinery. An object of the present invention is to provide a ground flare that prevents surrounding objects from resonating and vibrating.

In order to solve the above problems, the present invention employs the following means.
The ground flare according to the present invention is a ground flare tower in which combustible exhaust gas is burned with a burner at the lower end of a chimney, and the lower end of the chimney and the periphery of the burner are surrounded by a windshield. At least one selected from a change in the natural frequency generated from the body, a plurality of the ground flare towers, and a low-frequency vibration absorber installed inside the ground flare tower, The low-frequency noise sound pressure level is reduced.

  According to such a ground flare, the natural frequency generated from the ground flare tower body composed of the chimney and the windshield is changed, multiple ground flare tower bodies are installed, and the low frequency vibration absorber is installed inside the ground flare tower body. By selecting at least one of them and reducing the low-frequency noise sound pressure level of the ground flare tower body, it becomes possible to set the low-frequency vibration generated from the ground flare below the joinery vibration generation limit.

In the above invention, the natural frequency generated from the ground flare tower is changed by providing a windshield opening in a part of the windshield and closing the windshield opening with a non-walled sheet material for low-frequency sound. Preferably, this is done, whereby the sound pressure level can be lowered by changing the generated frequency in the direction of increasing.
In this case, it is preferable that the windshield opening has a peripheral opening ratio of 50% or more and a height opening ratio of 70% or more.
Moreover, what is necessary is just to select the sheet material surface density of the said non-wall-surface-ized sheet material according to the prevailing frequency before a windshield opening.

In the above invention, the natural frequency generated from the ground flare tower is preferably changed by providing a chimney opening in a part of the chimney, thereby changing the frequency to be generated. The sound pressure level can be lowered.
In this case, the chimney opening is preferably a lateral opening provided in a range of 90 ° to 360 ° in the circumferential direction. That is, the chimney opening of the present invention may be opened as large as the structural strength permits within a range of 90 ° to 360 ° in the circumferential direction.
Moreover, it is preferable that the height direction position of the said horizontal opening is arrange | positioned in the part used as the antinode of the sound pressure mode generate | occur | produced with a resonant frequency.
Moreover, about the said horizontal opening, it is preferable that an opening area ratio shall be 25% or more irrespective of opening shape.
A plurality of the lateral openings may be provided in the chimney height direction.

  In the above invention, the chimney opening may be one or more vertical openings that open in the height direction of the chimney.

  In the above invention, an opening concealment member is provided by providing a gap outside the chimney opening, and a gap area formed between the gap and the chimney is set larger than an opening area of the chimney opening. Thus, the sound pressure level can be lowered by changing the generated frequency in the direction of increasing, and the flame in the chimney can be prevented from being seen from the outside through the chimney opening by the opening concealing member.

In the above invention, the change of the natural frequency generated from the ground flare tower body is as follows: The burner position ζ ′ of the burner obtained by [Equation 1] is changed from the windshield entrance to the entire passage including the chimney and the windshield. It is preferable to be installed in the range of 2.2 to 3.4, and thereby the sound pressure level can be lowered by changing the generated frequency in the direction of lowering.
In this case, the length of the chimney and / or the windshield may be increased to extend the overall length of the passage.

  In the above invention, the plurality of the ground flare towers are preferably combined with ones having different dominant frequencies, so that the sound pressure level at each dominant frequency is lowered and dispersed. The noise level can be lowered.

In the above invention, the installation of the low-frequency vibration absorber inside the ground flare tower body suspends a large number of sheet materials at an inclination angle from the vertical direction in a noise passage formed between the windshield and the chimney. The sheet material absorbs the vibration energy of the air particles due to noise, so that noise can be reduced.
In this case, it is desirable that the inclination angle is set in a range of 10 ° to 60 °.
Moreover, it is desirable that the sheet material is bent into a plurality of pieces.
In addition, it is desirable to install a top plate above the entrance of the noise passage.

  According to the above-described present invention, the low frequency vibration generated from the ground flare can be made lower than the vibration generation limit of the joinery, and surrounding objects can be prevented from resonating and vibrating.

Hereinafter, an embodiment of a ground flare according to the present invention will be described with reference to the drawings.
The ground flare 10 shown in FIG. 1 is an apparatus for incinerating by burning the combustible gas with the burner 11 provided at the lower end of the chimney 20 with the lower end of the chimney 20 open. The lower end of the chimney 20 is surrounded by a windshield 40 around one or more burners 11. By providing such a windshield 40, the burner 11 disposed at the lower end of the chimney 20 is not affected by the surrounding wind, and the flame is not visible from the outside.

In the ground flare 10 thus configured, in the present invention, the natural frequency change of the low frequency sound (noise) generated from the ground flare tower body composed of the chimney 20 and the windshield 40, the ground flare composed of the chimney 20 and the windshield 40, and the like. Reduce the sound pressure level of the low-frequency noise of the ground flare tower by selecting at least one of the multiple towers and installing the low-frequency vibration absorber inside the ground flare tower consisting of the chimney 20 and the windshield 40 To do.
That is, the ground flare 10 of the present invention has a countermeasure for changing the natural frequency of the generated low-frequency sound, a countermeasure for making a plurality of ground flare towers, and a ground Select at least one of the measures to install a low-frequency vibration absorber inside the flare tower, and implement one or more measures in combination to reduce the low-frequency noise and sound pressure level of the ground flare tower. It is a thing.

In FIG. 2, the sound pressure level of the low frequency vibration (noise) generated from the ground flare tower in the ground flare 10 described above is indicated by a broken line. Here, the horizontal axis in the figure is the dominant frequency (Hz), and the vertical axis is the sound pressure level (dB).
According to this figure, the sound pressure level of the low-frequency vibration has a convex curve, and intersects with the joinery vibration occurrence limit indicated by the straight line rising to the right at the two dominant frequencies f1 and f2. Since the joinery vibration generation limit is the upper limit of the sound pressure level at which joinery vibration is generated, it is necessary to set the sound pressure level of low frequency vibration to a region lower than the joinery vibration generation limit. It should be noted that the sound pressure level before the measures described below is higher than the joinery vibration generation limit.
Therefore, the sound pressure level of the low frequency vibration generated from the ground flare tower of the ground flare 10 has a design suitable range in both the region where the dominant frequency is smaller than f1 and the region where the dominant frequency is larger than f2. . For this reason, in the low frequency vibration generated from the ground flare tower, the sound pressure level of the ground flare tower is less than the fixture vibration generation limit by lowering the dominant frequency from f1 or raising the dominant frequency from f2. Lower. As a result, the sound pressure level of the low-frequency vibration generated from the ground flare 10 can be set below the joinery vibration generation limit, and surrounding objects can be prevented from resonating and vibrating.

Hereinafter, the configuration and measures for reducing the low frequency noise (sound pressure level) of the ground flare 10 to be below the joinery vibration generation limit and within the design suitable range will be specifically described.
The configuration and measures described above are roughly divided into the following four.
1) The natural frequency of the low frequency sound generated from the ground flare tower is moved to the high sound side to prevent resonance with the natural frequency of burner combustion.
2) The natural frequency of the low frequency sound generated from the ground flare tower is moved to the low sound side to prevent resonance with the natural frequency of burner combustion.
3) Multiple ground flare towers, sound pressure reduction effect by lowering the heat of treatment, and the natural frequency of the multiple towers to be a frequency other than the natural frequency of the burner, and unique to multiple towers The frequency is also different.
4) An object that absorbs low-frequency vibration (low-frequency vibration absorber) is installed inside the tower of the ground flare.
By implementing these configurations and countermeasures singly or in appropriate combination, resonance of the natural frequency of burner combustion and ground flare column vibration is prevented, and the sound of low-frequency noise generated from the ground flare tower body is prevented. The pressure level can be reduced. Further, the low frequency vibration absorber can reduce the sound pressure level of low frequency noise by converting vibration energy into heat energy.

<Embodiment 1; high frequency shift of natural frequency>
In the embodiment described below, the natural frequency of the low frequency sound generated from the ground flare tower is moved to the high sound side to prevent resonance with the natural frequency of burner combustion.
In the ground flare 10 </ b> A shown in FIG. 3, a windshield opening 41 is provided in a part of the windshield 40, and the natural frequency is changed by closing the windshield opening 41 with a non-wall surface sheet material 42. That is, after a portion of the windshield 40 is cut out to provide the windshield opening 41, the non-wall surface sheet material 42 is attached to the windshield opening 41 to close it. The non-walled sheet material 42 used here is to prevent wind from being seen from the outside through the windshield opening 41, in addition to preventing wind and audible sound leakage, and function as a wall surface for low frequency sound. Any material that does not need to be used.

The windshield opening 41 provided by removing a part of the windshield 40 has an opening area with a circumferential opening ratio of 50% or more and a height opening ratio of 70% or more in the opening ratio defined below (see FIG. 3). Therefore, it is desirable to remove the plate material from the windshield 40, for example. In the illustrated windshield opening 41, curved rectangular openings are arranged at equal pitches in the circumferential direction.
Circumferential aperture ratio = n × w / πD × 100
n: Number of windshield openings
w: Perimeter of windshield opening
π: Circumference ratio
D: Diameter of windshield Height opening ratio = h / H × 100
h: Height of windshield opening
H: Overall height of windshield

FIG. 4 is a diagram showing the relationship between the aperture ratio (%) and the peak sound pressure level (dB).
In the case of the circumferential aperture ratio shown in FIG. 4A, the peak sound pressure level increases as the aperture ratio increases from 0, and reaches a peak when the aperture ratio is about 20%. After this peak, the peak sound pressure level decreases as the aperture ratio increases, and there is almost no fluctuation in the peak sound pressure level even if the aperture ratio increases to about 50% or more. Therefore, it is desirable that the circumferential aperture ratio be 50% or more.
In the case of the height aperture ratio shown in FIG. 4B, in the region where the aperture ratio is about 0 to 70%, the peak sound pressure level decreases as the aperture ratio increases. And in the area | region where an aperture ratio is larger than about 70%, there is almost no change of the peak sound pressure level according to the raise of an aperture ratio. Therefore, the height aperture ratio is desirably 70% or more.
In addition, as for the wind-shield opening part 41, it is desirable for both opening ratios to satisfy | fill the conditions about the periphery opening ratio and height opening ratio which were mentioned above.

  The non-wall surface sheet material 42 is obtained by installing a sheet material such as a soundproof sheet in the windshield opening 41 so as not to form a wall surface with respect to low frequency sound. As shown in FIG. 5, the range of the sheet material surface density suitable as the non-wall surface sheet material 42 varies depending on the prevailing frequency before the windshield opening. That is, it is necessary to select the non-walled sheet material 42 having a higher sheet material surface density and heavier as the prevailing frequency before the windshield opening is smaller. In other words, it is desirable to select the sheet material surface density of the non-wall surface sheet material 42 from an area below the boundary line of the design preferable range shown in FIG.

That is, when the surface density of the non-walled sheet material 42 is decreased, the dominant frequency is changed so that the surface density of the non-walled sheet material 42 is decreased, and the effect of the windshield opening is reduced. In order to obtain it, it is necessary to select a material having a surface density according to the initial frequency band.
Here, in order to increase the dominant frequency by making the windshield sheet at a frequency of 5 Hz, a material lighter than about 3000 g / m ² is selected, and in order to increase the dominant frequency by making the windshield sheet at a frequency of 25 Hz, approximately 300 g / In order to select a material lighter than m ² and increase the dominant frequency by making the frequency 80 Hz a windshield sheet, it is necessary to select a material lighter than approximately 30 g / m ² .

With such a configuration, the frequency of vibration generated from the ground flare 10 </ b> A is increased, so that a resonance point with the natural frequency of the burner 11 can be avoided.
In addition, high-frequency vibrations increase the attenuation in the chimney 20 and thus reduce the noise level. That is, the high frequency side movement of the natural frequency described here solves the problem of noise reduction of the conventional ground flare 10, and a windshield opening 41 is provided in a part of the windshield 40 to provide a non-walled sheet material 42. The sound pressure level of the low frequency noise is lowered while the generated frequency is increased.

Next, instead of the windshield opening 41 of the windshield 40 in Embodiment 1 described above, a modification in which a chimney opening is provided in a part of the chimney 20 will be described with reference to FIG. In this modification, in order to change the natural frequency generated from the ground flare tower body, that is, to move the natural frequency of the low frequency sound generated from the ground flare tower body to the high sound side, a part of the chimney 20 is used. A chimney opening 21 is provided to prevent resonance with the natural frequency of burner combustion.
A ground flare 10B shown in FIG. 6 includes a chimney opening 21 having a lateral opening provided at an appropriate position of the chimney 20 above the position surrounded by the windshield 40. The chimney opening 21 is provided in a range of 90 ° to 360 ° in the circumferential direction of the chimney 20, and is desirably as large as the structural strength allows.
In addition, the chimney opening 21 shown in FIG. 6 is set to a portion where the height direction position of the horizontal opening becomes an antinode of the sound pressure mode generated by the resonance frequency in order to efficiently reduce the sound pressure level in the chimney 20. ing.

For example, as shown in FIG. 7, the above-described chimney opening 21 having a lateral opening may employ a round hole or a square hole as an opening shape at the time of opening, and the opening shape is not particularly limited. However, the opening area ratio of the chimney opening 21 is preferably 25% or more regardless of the opening shape of the lateral opening. That is, for example, as shown in FIG. 7A, the opening area ratio S when the chimney opening 21 has a curved rectangular shape, or for example, as shown in FIG. In this case, the opening area ratio S ′ is 25% or more.
7A, n is the number of the chimney openings 21, w is the circumferential length of the chimney openings 21, and h is the height of the chimney openings 21, 7 (b), where n is the number of the chimney openings 21 ', π is the circumference, d is the diameter of the chimney openings 21', D 'is the diameter of the chimney 20, h is the height of the chimney opening 21 '.

By the way, the above-described chimney opening portions 21 and 21 ′ of the horizontal opening are provided only in one step in the height direction of the chimney 20. For example, as shown in FIG. 8, a plurality of steps are provided in the height direction of the chimney 20. It may be provided side by side.
In the configuration example of the chimney 20 </ b> A shown in FIG. 8, a circular truncated cone-shaped ring member 23 is fixed to a plurality of column members 22 at an equal pitch in the height direction, and formed between the upper and lower ring members 23, 23. A large number of gaps function as the multi-stage chimney opening 21A. In this case, by considering the vertical arrangement of the ring member 23, it is possible to make the chimney opening 21 </ b> A in which the opening is not visible when the chimney 20 </ b> A is viewed from the horizontal direction, that is, the flame is difficult to see from the outside. .

Moreover, unlike the horizontal opening mentioned above, the chimney 20B shown in FIG. 9 is provided with the chimney opening part 21B of the vertical opening opened to a chimney height direction. In the configuration example shown in the figure, a pair of chimney members 24, 24 having a substantially C-shaped cross section are used, and two chimney opening portions 21B having a vertical opening are formed.
In addition, in the case of the chimney 20C shown in FIG. 10, a single chimney opening 21C having a vertical opening is provided. In the chimney opening 21C, an opening concealment member 25 is provided at a predetermined interval outside the chimney 20C so that the flame cannot be seen from the outside. The gap area formed between the chimney 20C and the opening concealing member 25 is set larger than the opening area of the chimney opening 21C so as not to impair the low-frequency noise reduction effect. Furthermore, such an opening concealment member 25 can be installed also in the chimney opening 21 or the like of the lateral opening. For example, as shown in FIG. 11, the opening concealment member covers the outer periphery of the chimney opening 21 of the lateral opening. 25 'can be installed. In this case, the gap area (Sa × 2) formed between the chimney 20 and the opening concealing member 25 ′ is set larger than the opening area Sb of the chimney opening 20 (2Sa> Sb).

As described above, even in the configuration in which the chimney opening 21 is provided on the chimney 20 side, the frequency of vibration generated from the ground flare 10B ′ is increased similarly to the wind tunnel opening 41, so that the natural frequency of the burner 11 is It is possible to avoid the resonance point.
In addition, high-frequency vibrations increase the attenuation in the chimney 20 and thus reduce the noise level. That is, the high frequency side movement of the natural frequency described here has a structure in which the chimney opening 21 is provided in a part of the chimney 20 in order to solve the noise reduction problem of the conventional ground flare 10, and the generated frequency is increased. However, the sound pressure level of the low frequency noise is lowered.

<Embodiment 2: Low frequency shift of natural frequency>
In the embodiment described below, the natural frequency of the low-frequency sound generated from the ground flare tower is moved to the low sound side to prevent resonance with the natural frequency of burner combustion. That is, as shown in FIG. 12 to FIG. 15, the sound pressure level of low frequency noise is lowered while extending the windshield portion to lower the generated frequency.
In this method, the burner position ζ ′ of the burner 11 obtained using FIG. 15 and [Equation 1] shown below is from the entrance Wi of the windshield 40A with respect to the length including the chimney 20 and the windshield 40A (total length of the passage). It is installed in the range of 2.2 to 3.4.

ここで、〔数１〕においては、Ｌ１が煙突高さ（ｍ）、ｄ１が煙突の直径（ｍ）、ｃが音速（ｍ／ｓ）、ｆが計測周波数（Ｈｚ）である。
そして、〔数１〕により算出したバーナ位置ζ′とピーク音圧レベルとの関係は、図１５に示すように、ピーク音圧レベルはピークを過ぎて低下する。従って、バーナ位置ζ′の設計好適範囲は、入口Ｗｉのピーク音圧レベル（ζ′＝０のピーク音圧レベル）より低い値になる領域（ζ′＝２．２〜３．４）となる。

Here, in [Equation 1], L1 is the chimney height (m), d1 is the chimney diameter (m), c is the speed of sound (m / s), and f is the measurement frequency (Hz).
The relationship between the burner position ζ ′ calculated by [Equation 1] and the peak sound pressure level decreases as the peak sound pressure level passes the peak as shown in FIG. Therefore, the preferable design range of the burner position ζ ′ is a region (ζ ′ = 2.2 to 3.4) that is lower than the peak sound pressure level of the inlet Wi (peak sound pressure level of ζ ′ = 0). .

In order to set the burner position ζ ′ within the above-described design preferable range, the windshield length is extended as a windshield 40A in which a one-fold turn 43 is provided on the windshield 40, for example, as a ground flare 10D shown in FIG. In the windshield 40A having such a one-stage folding 43, the opening Wi of the windshield 40A is disposed downward.
Further, as in the windshield 40B of the ground flare 10E shown in FIG. 13, the windshield length may be extended by two-stage folding 43, 44 (or a plurality of stages of two or more stages), for example, the ground shown in FIG. As in the case of the windshield 40C of the flare 10F, the folded portion 43 may be combined with a laterally extending portion 45.

  With such a configuration, the frequency of vibration generated from the ground flares 10D to 10F is lowered by the extension of the windshield length and / or the extension of the chimney length. By reducing the frequency in this way, it is possible to avoid a resonance point with an object that causes a problem due to vibration. Furthermore, since the volume of the ground flares 10D to 10F increases, the internal attenuation increases, so that the noise level decreases.

<Embodiment 3;
In the embodiment described below, the sound pressure level is reduced by combining a plurality of ground flare towers and combining different ground frequencies.
In this embodiment, for example, as shown in FIG. 16, two ground flares 10a and 10b divided into two so as to satisfy a required capability are provided. In this case, the ground flares 10a and 10b divided into two are set such that the chief stacks of the chimneys 20a and 20b have different chimney lengths or the like so that the respective dominant frequencies are different. Has a low frequency, and the ground flare 10a having a short air column length has a high frequency. That is, the two ground flares 10a and 10b are arranged with different primary frequencies. In this division example, the chimney and the windshield are both divided into two. In addition, the code | symbol 40a, 40b in a figure has shown the windshield.

Thus, if two ground flares 10a and 10b having different dominant frequencies are installed side by side, as shown in the lower part of FIG. 20, the sound pressures do not overlap each other due to the difference in the primary frequency. Accordingly, each sound pressure level is reduced (about 3 dB) by dividing into two parts, so that the sound pressure level as the entire ground flare (10a, 10b) is suppressed to the joiner vibration generation limit indicated by the one-dot chain line in FIG.
However, when two ground flares having the same dominant frequency are arranged side by side, the primary frequencies are the same, and therefore, as shown in the upper part of FIG. Therefore, it is difficult to suppress the sound pressure level of the entire ground flare (10a, 10b) to be less than the joinery vibration generation limit indicated by the one-dot chain line in the drawing.

  By the way, the above-described plurality of ground flare towers are not limited to the above-described two divisions, and may be divided into three or more divisions. In this case, it is not necessary to evenly distribute the amount of gas to be processed if each tower frequency is set to have a different value and is multi-columned. Accordingly, the sound pressure level can be appropriately adjusted according to the output sound pressure level, so that the sound pressure level can be lowered in a desired frequency band.

In the example of division shown in FIG. 17, only the chimney is divided into 20a, 20b, and 20c by sharing the windshield. Also in this case, the dominant frequencies are set to be different by changing the chimney lengths.
In the example of division shown in FIG. 18, the chimney 20D having a circular cross section is divided into three parts by partitioning with the partition member 26, and the dominant frequency is changed by changing the height position of the chimney opening 21, for example. Is set to Further, the cross-sectional shape of the chimney 20D is not limited to a circular cross-section. For example, as shown in FIG. 19, the inside of the chimney 20E having a hexagonal cross-section may be divided into three parts by a partition member 26.

<Embodiment 4: Sound absorbing material method>
In the embodiment described below, a low-frequency vibration absorber is installed inside the ground flare tower body, and the vibration energy of air particles due to noise is absorbed to reduce noise.
In the embodiment shown in FIG. 21 and FIG. 22, the noise passage 50 formed between the windshield 40 and the chimney 20 is inclined from the vertical direction as a low-frequency vibration absorber installed inside the ground flare tower body. A large number of sheet materials 60 are suspended in a comb shape. The sheet material 60 in this case is plate-shaped, and the inclination angle for suspending the sheet material 60 is set in a range of 10 ° to 60 ° with respect to the vertical direction.

That is, by installing the sheet material 60 in an inclined manner, low-frequency noise in the noise passage 50 is prevented from going straight through the gap formed between the sheet materials 60 and 60. As a result, the low frequency noise is reflected on the surface of the sheet material 60, so that the noise reduction effect can be enhanced, and further, the reduction of the intake air amount due to the suspension of the sheet material 60 can be prevented. Therefore, since the sheet material 60 efficiently absorbs the vibration energy of the air particles due to the low vibration noise, the low vibration noise can be reduced.
In the embodiment described above, the sheet material 60 is plate-shaped, but for example, as shown in FIG. 23, a sheet material 61 that is bent once or a plurality of times in a dogleg shape may be adopted. Such a sheet material 61 makes it more difficult for the low-frequency noise to go straight in the noise passage 50, so that the contact area with the air particles can be increased and the noise reduction effect can be improved.

Moreover, it is desirable to provide a top plate 70 at the upper entrance of the noise passage 50 described above. The top plate 70 is installed at a predetermined interval from the entrance (upper opening) of the noise passage 50 and is installed so as to cover the entrance of the noise passage 50 in plan view.
When such a top plate 50 is installed, since the straight advance of the low frequency noise is hindered, the noise reduction effect can be further improved.

As described above, each of Embodiments 1 to 4 described above has a sufficient low frequency noise reduction effect, but each embodiment is appropriately combined according to various conditions such as the flare stack and the installation location thereof. May be implemented.
In the embodiment of the combination shown in FIG. 1, the chimney opening 21 provided in the chimney 20, the windshield opening 41 provided in the windshield 40, the sheet material 60 installed in the noise passage 50, and the upper entrance of the noise passage 50 The top plate 70 installed at the same time is employed at the same time, but is not limited thereto. A non-wall surface sheet material 42 is attached to the windshield opening 42, and an opening concealing member 25 ′ is attached to the outer periphery of the chimney opening 21.

As described above, the ground flare of the present invention is a modification of the natural frequency generated from a chimney and a wind flare tower, a plurality of ground flare towers, and low-frequency vibration absorption inside the ground flare tower. Since at least one of the body installations is selected to reduce the low frequency noise sound pressure level of the ground flare tower, the low frequency vibration generated from the ground flare is set below the vibration generation limit of the fixture, and the surrounding objects resonate.・ Vibration can be prevented.
In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary of this invention, it can change suitably.

It is sectional drawing which shows a structural example as one Embodiment of the ground flare which concerns on this invention. It is a figure which shows the sound pressure level of the low frequency vibration generate | occur | produced from a grand flare tower body. It is a perspective view which shows the structural example of a windshield opening part as Embodiment 1 (high-frequency side movement of a natural frequency) of the ground flare which concerns on this invention. It is a figure which shows the relationship between the aperture ratio of a windshield opening part, and a peak sound pressure level, (a) is a relationship between a circumferential aperture ratio and a peak sound pressure level, (b) is a height aperture ratio and a peak sound pressure level. It is a relationship. It is a figure which shows the relationship between the prevailing frequency before windshield opening, and a sheet material surface density about the design suitable range of a non-wall-ized sheet material. It is a perspective view which shows the structural example of the chimney opening part made into horizontal opening as a modification of Embodiment 1. FIG. It is a figure which shows the definition of the opening area ratio which concerns on the chimney opening part of a horizontal opening, (a) is the opening area ratio S of the curved rectangle, (b) is the opening area ratio S 'of a circular hole. It is a figure which shows the structural example of the chimney opening part which made the horizontal opening multistage, (a) is a perspective view, (b) is a longitudinal cross-sectional view. It is a perspective view which shows the structural example of the chimney opening part made into the vertical opening. It is a figure which shows the structural example which attached the opening concealment member to the chimney opening part made into the vertical opening, (a) is a perspective view, (b) is a cross-sectional view. It is a figure which shows the structural example which attached the opening concealment member to the chimney opening part made into horizontal opening, (a) is a perspective view, (b) is a longitudinal cross-sectional view. FIG. 7 is a diagram showing a configuration example in which the windshield is folded and the windshield length is extended as Embodiment 2 of the ground flare according to the present invention (low frequency side movement of natural frequency), (a) is a cross-sectional view, (b) Is a longitudinal sectional view. As a modification of Embodiment 2, it is a figure which shows the structural example which folded the windshield in two steps and extended the windshield length, (a) is a cross-sectional view, (b) is a longitudinal cross-sectional view. As a modified example of Embodiment 2, it is a figure which shows the structural example which combined the extension to a side with the folding of a windshield, and extended the windshield length, (a) is a cross-sectional view, (b) is a longitudinal cross-sectional view. is there. It is a figure which shows a design suitable range in the relationship between burner position (zeta) 'and a peak sound pressure level. It is a perspective view which shows the structural example which made 2 towers as Embodiment 3 (multiple towers) of the ground flare which concerns on this invention. FIG. 10 is a perspective view showing a configuration example in which chimneys are made into three towers as a modification of the third embodiment. As a modification of Embodiment 3, it is a figure which shows the structural example which divided | segmented the inside of a chimney into 3 towers, (a) is a perspective view, (b) is a cross-sectional view. It is a cross-sectional view showing a configuration example in which the inside of a chimney having a hexagonal cross section is divided into three towers. It is explanatory drawing regarding the superposition | superposition of a dominant frequency in multiple tower formation of a ground flare. It is a perspective view which shows Embodiment 4 (sound-absorbing material system) of the ground flare which concerns on this invention. It is a front view which shows the example of arrangement | positioning of the sheet | seat material (part) shown in FIG. It is a front view which shows the example of arrangement | positioning at the time of bending the sheet | seat material (part) shown in FIG. 21 in a square shape. It is a figure which shows the structural example of an incinerator as a prior art example of a combustion process of combustible gas. It is a figure which shows the structural example of an open flare stack as an example of the conventional apparatus which carries out a combustion process of combustible gas. It is a figure which shows the prior art example of a ground flare.

Explanation of symbols

10, 10A to 10F Ground flare 11 Burner 20, 20A to 20E Chimney 21, 21A to 21C Chimney opening 25, 25 'Opening concealment member 40, 40A to 40C Windshield 41 Windshield opening 42 Non-walled sheet material 50 Noise passage 60 61 Sheet material 70 Top plate

Claims (18)

Combustible exhaust gas is burned with a burner at the lower end of the chimney, and in the ground flare where the lower end of the chimney and the periphery of the burner are surrounded by a windshield,
At least one of a change in natural frequency generated from a ground flare tower body including the chimney and the windshield, a plurality of the ground flare tower bodies, and a low-frequency vibration absorber installed in the ground flare tower body The ground flare characterized in that the low-frequency noise sound pressure level of the ground flare tower body is reduced.   The natural frequency generated from the ground flare tower body is changed by providing a windshield opening in a part of the windshield and closing the windshield opening with a non-walled sheet material for low-frequency sound. The ground flare according to claim 1.   The ground flare according to claim 2, wherein the windshield opening portion has a peripheral opening ratio of 50% or more and a height opening ratio of 70% or more.   The ground flare according to claim 2 or 3, wherein the sheet material surface density of the non-walled sheet material is selected according to a prevailing frequency before a windshield opening.   2. The ground flare according to claim 1, wherein the natural frequency generated from the ground flare tower is changed by providing a chimney opening in a part of the chimney.   The ground flare according to claim 5, wherein the chimney opening is a lateral opening provided in a range of 90 ° to 360 ° in the circumferential direction.   The ground flare according to claim 6, wherein the position in the height direction of the lateral opening is arranged at a portion that becomes an antinode of a sound pressure mode generated by a resonance frequency.   The ground flare according to claim 6 or 7, wherein an opening area ratio of the lateral openings is 25% or more.   The ground flare according to claim 6, wherein a plurality of the lateral openings are provided in a chimney height direction.   The ground flare according to claim 5, wherein the chimney opening is one or more vertical openings that open in a chimney height direction.   An opening concealment member is provided with a gap provided outside the chimney opening, and a gap area formed between the gap and the chimney is set larger than an opening area of the chimney opening. Item 11. The ground flare according to any one of Items 5 to 10.   The change of the natural frequency generated from the ground flare tower body is such that the burner position ζ ′ of the burner obtained by [Equation 1] is 2.2-3 The ground flare according to claim 1, wherein the ground flare is installed in a range of .4.   The ground flare according to claim 12, wherein the length of the chimney and / or the windshield is increased to extend the entire length of the passage.   2. The ground flare according to claim 1, wherein the plurality of ground flare towers are combined with ones having different dominant frequencies.   The installation of the low-frequency vibration absorber inside the ground flare tower body is performed by suspending a large number of sheet materials with an inclination angle from the vertical direction in a noise passage formed between the windshield and the chimney. The ground flare according to claim 1, wherein   The ground flare according to claim 15, wherein the inclination angle is set in a range of 10 ° to 60 °.   The ground flare according to claim 15, wherein the sheet material is bent into a plurality of pieces. The ground flare according to any one of claims 15 to 17, wherein a top plate is installed above the entrance of the noise passage.

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