JP2004054157A - Reducing method for noise - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To freely select the installation place of a gas turbine cogeneration apparatus etc., by greatly reducing the level of noise leaking out of even a noise source which radiates the noise radially like a boiler and a turbine. <P>SOLUTION: An exciting device 6 for noise elimination which has the noise source 1 in a box body 2 and equipped with a noise detector 6a on a wall plate 3 of the box body 2 is provided and the device 6 vibrates the wall plate 3 of the box body 2 to generate a vibration sound X for noise elimination which has a sound pressure frequency distribution approximating the sound pressure frequency distribution of noise N detected by the noise detector 6a and also has a 180° retardation, so that the vibration sound X for noise elimination cancels the noise N generated by the noise source 1. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for reducing noise generated by industrial equipment and the like, and forcibly vibrating a wall plate of a box surrounding a noise source to generate a vibration sound for noise reduction in an anti-phase relationship with the noise. Further, the present invention relates to a noise reduction method for reducing the noise level outside the box by canceling out the noise with the vibration noise for noise reduction.
[0002]
[Prior art]
Reduction of noise generated by industrial equipment such as boilers, turbines, and generators has become an important issue from the viewpoint of environmental protection. Various techniques have also been developed for silencing (or reducing sound).
[0003]
For example, as the method of silencing (reducing) the noise generated by the latter, (1) a method of storing a noise source in an enclosure lined with a sound-absorbing material, a method of surrounding a wall made of a high-mass material, and (2) a method of A method of providing a silencing muffler at an exhaust port of an enclosure covering a source has been widely adopted.
However, all of these silencing methods have problems in that the silencing equipment becomes large and a sufficient silencing effect cannot be obtained.
[0004]
On the other hand, in exhaust gas ducts of refuse incinerators and power generation boilers, a microphone for sound collection should be installed near the noise source on the upstream side of the exhaust gas duct, and a muffler speaker should be installed downstream of the exhaust gas duct. A sound having a frequency distribution substantially the same as that of the noise collected by the microphone and having an opposite phase (a phase difference of 180 °) is emitted from the silencing speaker, and a sound from the noise source is emitted from the silencing speaker. There has been developed a noise reduction method called active noise reduction that cancels out sound.
[0005]
The above-mentioned noise reduction method has a limited condition that a sound wave propagation path has a closed shape like an exhaust gas duct and is elongated in one direction, and a sound wave from a noise source propagates mainly in one direction. Thus, a relatively excellent noise reduction effect can be obtained.
However, in the case where the sound propagates radially from the noise source, even if the noise source is housed in a closed metal box, and the noise reduction method using the sound-collecting microphone and the silencing speaker is applied thereto, However, mutual interference between the sound from the noise source and the sound for muffling from the speaker does not occur well, and as a result, the noise often increases, which is difficult to put to practical use.
[0006]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has the above-mentioned problem in the conventional noise control of industrial equipment such as boilers and turbines. (2) Even if the so-called active noise reduction method is applied to the housing as it is, no satisfactory noise reduction effect can be obtained, and on the contrary, noise increases. It is intended to solve the problem that there is a fear that each wall plate of a steel storage box covering a noise source such as industrial equipment has a sound pressure frequency distribution substantially the same as noise and A noise reduction method that can efficiently reduce noise even when the noise source is an industrial device that radiates noise radially by applying a vibration force that generates a vibration noise for noise cancellation with the opposite phase. To provide.
[0007]
[Means for Solving the Problems]
The present inventors have for many years been a package type gas turbine cogeneration system in which a gas turbine generator unit, an exhaust heat recovery heat exchanger unit, a power device unit, and a control device unit are housed in a thin steel cabinet. The development of a device (hereinafter referred to as a GTCG device) and its practical use test have been performed.
Through the practical use test of these GTCG devices, the inventors simply store the gas turbine generator unit, which is the main noise source, in a sound deadening box, or replace the units constituting the GTCG device with a sound absorbing material. It is difficult to reduce the noise drastically simply by storing it in a cabinet made of thin steel sheets to which the affixing is applied. However, the condition that each wall plate (steel plate) forming the cabinet has a specific relationship with the sound pressure frequency and phase of the noise It has been found that by mechanically vibrating underneath, the level of noise outside the cabinet can be considerably reduced even when the cabinet is not an airtight enclosure.
[0008]
Therefore, the present inventors repeated many noise reduction tests for various GTCG devices while changing the characteristics of mechanical vibration applied to the cabinet, the structure of the cabinet, and the like, and analyzed the test results.
The invention of the present application has been made based on the results of the above noise reduction test. The invention of claim 1 accommodates a noise source in a box body and a noise detector on a wall plate of the box body. By providing a vibration damping device provided with a, by vibrating the wall plate of the box by the vibration damping device, the sound pressure frequency distribution approximate to the sound pressure frequency distribution of the noise detected by the noise detector It is a basic configuration of the present invention to generate a noise-reducing vibration sound having a phase difference of 180 ° and to cancel noise generated from a noise source by the noise-reducing vibration sound.
[0009]
According to a second aspect of the present invention, in the first aspect of the present invention, the box body is a box body having a thin metal wall plate on four sides and a ceiling, and the sound deadening vibration device having a noise detector is provided. Are provided on the wall plates of the four circumferences.
[0010]
According to a third aspect of the present invention, in the first aspect of the present invention, the box body is formed of a support frame and a thin metal wall plate supported and fixed to the support frame, and the wall plate is provided with an elastic body having an elasticity. It is interposed and supported and fixed to the support frame.
[0011]
According to a fourth aspect of the present invention, in accordance with the first aspect of the present invention, the silencing vibration sound generated by the silencing vibration device is converted into a peak sound pressure having a frequency substantially equal to the peak sound pressure in the sound pressure frequency distribution of the noise. It has what has.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of an industrial equipment device to which a noise reduction method according to the present invention is applied. In FIG. 1, reference numeral 1 denotes a noise source (industrial equipment) such as a generator or a gas turbine; 2 is a box for storing a noise source, 3 is a thin metal wall plate forming a box, 3a is a front wall plate, 3b is a rear wall plate, 3c is a left wall plate, 3d is a right wall plate, and 3e is a right wall plate. A ceiling wall plate (not shown), 3f is a floor wall plate, 4 is a support frame forming a box, 5 is an exciter, and 6 is a vibrating device for silencing.
[0013]
The industrial equipment 1 serving as the noise source is a gas turbine, a generator, a boiler, a transformer, a composite thereof, or the like, and emits a noise having a specific sound pressure frequency distribution in a radial manner by operation thereof.
[0014]
The storage box 2 is a cabinet having a square cross section, and the industrial equipment 1 is stored in the internal space.
The box 2 is formed of a support frame 4 having a square cross section forming a frame of the box, and a rectangular wall plate 3 made of a thin steel plate supported and fixed on six surfaces around the frame. The wall plates 3a to 3f are provided with holes such as intake holes and exhaust holes (not shown) as necessary.
[0015]
In addition, each wall plate 3 has an exciting body 5 made of an elastic body so that the vibration performance of the wall plate 3 can be enhanced and a vibration sound for noise reduction close to the sound pressure frequency distribution of noise can be generated as described later. And is fixed to the support frame 3.
The wall plates 3a to 3f forming the box 2 may be directly fixed to the support frame 4 by welding, or may be detachably fixed by bolts and nuts.
Further, each of the wall plates 3a and 3b can be attached to the support frame 4 so as to be openable and closable.
[0016]
The steel sheet forming each of the wall plates 3 is vibrated at a predetermined high frequency by the sound damping vibration device 6 as described later, and performs the function of a so-called speaker diaphragm for generating a vibration sound for sound damping. is there. Therefore, the thickness of the steel sheet is optimally about 1.0 to 3.2 mm, and its mounting structure should be a structure suitable for using the exciter 5 and performing high-frequency vibration as described above. desirable.
[0017]
The silencing vibration device 6 is provided on the four side walls 3 a to 3 d and the ceiling wall 3 e (not shown) of the box 2, and the bottom wall 3 f of the box 2 is appropriately provided as necessary. Is provided.
[0018]
As shown in FIG. 2, the noise damping vibration device 6 includes a noise detector 6a such as a microphone for detecting a noise N from a noise source, an amplifier 6b of a noise signal QN from the noise detector 6a, and a sound pressure of the noise signal QN. The sound pressure frequency analyzer 6c for analyzing the frequency distribution, the phase inverter 6d for shifting the phase of the signal QN from the sound pressure frequency analyzer 6c by 180 °, and the intensity level and frequency distribution of the vibration signal Qf from the phase inverter 6d are An intensity / frequency adjuster 6e to be adjusted, a vibration generator 6f for vibrating the wall plate 3 at a predetermined frequency and amplitude based on the vibration signal Qf, a vibration sound detector 6g for detecting a vibration sound X for silencing, a detected vibration It comprises an amplifier 6h for the sound signal QX, a sound pressure frequency analyzer 6i for the vibration sound signal QX, a comparator 6k for the analyzed vibration sound signal QX and the noise signal Qf from the phase inverter 6d, and the like. By vibrating the wall plate 3 with the vibration force Pf from the vessel 6f, a noise-reducing vibration sound X having substantially the same sound pressure frequency distribution as the noise N is generated, and the noise N is canceled by the vibration sound X. Thereby, the noise N leaking to the outside of the box 2 is reduced.
[0019]
Note that in FIG. 2, the muffled vibration sound X having substantially the same sound pressure frequency distribution as that of the noise signal QN detected by the noise detector 6 a and having only the phase inverted by 180 ° is generated by the vibration force Pf. However, if there is a large sound pressure peak value in the sound pressure frequency distribution of the noise signal QN detected by the sound pressure frequency analyzer 6c, the muffling vibration sound X having a peak value corresponding to the peak sound pressure frequency is generated. The center vibration sound may be generated by the vibration force Pf.
[0020]
In the embodiment of FIG. 1, the vibration exciter 6 for noise suppression provided with the noise detector 6a is provided at the center of each of the five peripheral surfaces except the bottom surface of the box 2. Depending on the installation location of the body 2, for example, the silencing vibration device 6 may be provided only on both side wall plates 3 a and 3 b of the box 2.
[0021]
Next, the operation of the present invention will be described.
With reference to FIG. 1, when the noise N radiates from the noise source 1 due to the operation of the industrial equipment or the like, the sound pressure frequency distribution of the noise N is detected and analyzed by the vibration damping device 6, A vibration force Pf that generates a noise-canceling vibration sound X having a sound pressure frequency distribution substantially equal to the sound pressure frequency distribution of the detected noise and having a phase difference of 180 ° is output from the vibration generator 6f. A force Pf is applied to the wall plate 3.
As a result, each wall plate 3 emits a noise-canceling vibration sound X having a phase opposite to that of the noise N and having substantially the same sound pressure frequency distribution, and the noise N incident on each wall plate 3 is reduced. Thus, the level of the noise that leaks out of the wall plate 3 is reduced by being canceled by the silencing vibration sound X generated by the muffler 3.
[0022]
Note that the sound pressure frequency distribution generated by the vibration generators 6f of the five sound deadening vibrating devices 6 provided on each wall plate may vary greatly depending on the type of the noise source 1, but usually any wall plate is used. 3 also emits the vibration sound X for silencing having substantially the same sound pressure frequency distribution.
[0023]
【Example】
FIGS. 3 to 6 are external views of the small-capacity gas turbine cogeneration apparatus used in the embodiment of the present invention, and show a front view, a side view, a rear view, and a plan view of the box 2.
The box 2 is formed of a rectangular support frame 4 for supporting and fixing each device and a wall plate 3 supported and fixed to the support frame 4, and each wall plate 3 is attached to and detached from the support frame 4. Mounted freely. 3 to 6, 9 is an air outlet, 10 is an air inlet, 11 is an exhaust gas outlet, 12 is a fuel gas inlet, 13 is a low temperature water inlet, 14 is a high temperature water outlet, and 15 is an exhaust pipe. And are provided on the 1.2 mm-thick steel plate 3 forming the box 2.
[0024]
FIG. 7 is a longitudinal sectional view of the small-capacity gas turbine cogeneration system used in the embodiment of the present invention. A heat recovery heat exchanger (hot water boiler) and hot water circulation An exhaust heat recovery unit T including a pump, a power device unit E such as a transformer, a converter, an inverter and a battery controller, and various devices such as a fuel gas filter and a gas compressor are arranged. A small-capacity gas turbine generator unit U, a cooling fan 16, a control unit C, and the like are provided in an upper part of the storage box 2. The control unit C on the front of the box 2 drives, controls, and monitors the operation of the apparatus. Is performed.
[0025]
FIG. 8 is a schematic explanatory view of the gas turbine generator unit U of the apparatus used in the embodiment of the present invention, and includes a compressor 17, a combustion chamber, a turbine 19, a generator 18, a regenerator 20, and a regenerator casing. The gas turbine generator unit U is formed by integrally assembling the gas turbine 21 and the exhaust gas port 22.
[0026]
The gas turbine generator unit U is rotated at a high speed of about 96,000 RPM, generates 28 kW, and sends turbine exhaust gas from the gas turbine generator unit U to an exhaust heat recovery heat exchanger T provided at a lower portion to generate heat. , A heat output (hot water or steam) of about 56 KW is generated.
Moreover, the cooling air A of the combustion air and equipment enters into the interior than in hole 10 an air intake on the front lower part of the box body 2 as shown in FIG. 7, the combustion air A ₀ is a gas turbine generator unit U It is sucked inside. Further, the cooling air Ac cools the power equipment unit E, the exhaust heat recovery unit T, the control unit C, and the like, and then flows into the sound deadening box 23 of the gas turbine generator unit U to cool the gas turbine generator unit U. Then, the cooling fan 16 discharges the air from the air outlet 9 on the rear side of the box 2 to the outside.
[0027]
The vibrating device 6 for noise reduction is provided at approximately the center of three walls on the right side, left side, and front surface of the box 2 so as to apply a vibration force Pf of a sound pressure frequency distribution described later to each wall 3. I have to.
[0028]
FIG. 9 is an actual measurement diagram of the sound pressure frequency distribution of the noise N when the small capacity gas turbine cogeneration apparatus according to the embodiment of the present invention shown in FIGS. (Height: 1750 mm, width: 790 mm, depth: 1950 mm) Measured at a central position (about 900 mm in height) P at a distance of 1 m from the left side wall plate 3a.
As is clear from FIG. 9, the peak value of the noise N is at the points of the frequency 3.2 KHz and the frequency 6.4 KHz, the peak value at 3.2 KHz is 81 dBA, and the peak value at 6.4 KHz is 40.5 dBA. .
At this time, the average value of the noise (sound pressure) at a point P 1 m away from the right side wall 3c is about 83.7 dBA, and the noise source 1 (the average sound pressure of the original sound) in the storage box 2 Was about 95 dBA.
[0029]
On the other hand, as described above, the sound deadening vibrating devices 6 are installed at substantially the center portions of both side walls and the front side wall of the storage box 2, and the sound deadening vibrating devices 4 are operated. By applying a vibration force Pf for noise reduction to each wall plate 3 and vibrating each wall plate 3, the position P has a sound pressure peak value of about 81 dBA at a point of about 3.2 KHz, and A silencing vibration sound (average sound pressure at position P of about 81 dBA) X having a phase opposite to that of the noise N was generated.
The vibration intensity (amplitude) of the vibration force Pf applied to each wall plate 3 is determined by operating the silencing vibration device 6 in a state where the operation of the device is stopped and the vibration noise X generated by the vibration device 6. Is set in advance by adjusting the vibration intensity / frequency adjuster 6e so that the average sound pressure at the point P at the distance 1m is about 83.7 dBA.
[0030]
When the silencing vibration device 6 was operated to generate the silencing vibration sound X, the average noise sound pressure at the position P was 63 dBA.
Further, the peak noise sound pressure at the point of the frequency 3.2 KHz was 60 dBA, and the peak noise sound pressure at the point of the frequency 6.4 KHz was 39.0 dBA.
[0031]
That is, the average sound pressure of the noise N is 83.7 dBA to 63 dBA, the peak noise sound pressure of 3.2 KHz is 81 dBA to 60 dBA, and the peak sound pressure of 6.4 KHz is 40.5 dBA to 39.0 dBA, respectively. As a result, the noise N can be significantly reduced.
[0032]
In this embodiment, only noise measurement is performed at a point P having a height of about 900 mm, which is 1 m away from the left side surface 3c of the storage box 2, but the same noise effect can be obtained on all side surfaces. .
[0033]
【The invention's effect】
In the present invention, a sound deadening vibrating device provided with a noise detector is provided on a wall plate of a box, and the wall plate of the box is vibrated by the vibrating device for sound damping, whereby the noise detector is used. It has a sound pressure frequency distribution that is close to the sound pressure frequency distribution of the detected noise, and generates a noise-canceling vibration sound having a phase difference of 180 °, and the noise generated from the noise source is canceled by the noise-canceling vibration sound.
As a result, even in the case of a noise source such as industrial equipment that emits noise radially, noise can be efficiently reduced in real time.
Further, in the present invention, since the wall plate of the box housing the noise source is used as a diaphragm for generating the vibration noise for noise reduction, the vibration noise for noise reduction becomes a planar sound source and is emitted radially from the noise source. It is possible to more effectively cancel the noise that is generated.
The present invention has excellent practical utility as described above.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an apparatus to which a noise reduction method according to the present invention is applied.
FIG. 2 is a block diagram showing an example of a sound deadening vibration device used in the present invention.
FIG. 3 is a front view of a box of the gas turbine cogeneration apparatus used in the embodiment of the present invention.
FIG. 4 is a left side view of the box.
FIG. 5 is a rear view of the box.
FIG. 6 is a plan view of the box.
FIG. 7 is a vertical sectional view of a box.
FIG. 8 is a partially cutaway explanatory view of a gas turbine generator unit provided in an apparatus used for carrying out the present invention.
FIG. 9 is an actual measurement diagram of a sound pressure frequency distribution of noise when the small capacity gas turbine cogeneration apparatus according to the embodiment of the present invention is operated at rated operation.
[Explanation of symbols]
N is noise, QN is a noise signal, Qf is a vibration signal, Pf is a vibration force, X is a vibration sound for silencing, QX is a vibration sound signal, U is a gas turbine generator unit, T is a waste heat recovery heat exchange unit, C control unit, E is the power equipment unit, A is air, A ₀ is the combustion air, Ac is cooling air, 1 noise source (industrial equipment), 2 storage box body, 3 wallboard, 3a Is a front wall plate, 3b is a rear wall plate, 3c is a left wall plate, 3d is a right wall plate, 3e is a ceiling wall plate, 3f is a floor wall plate, 4 is a support frame, 5 is an exciter, and 6 is a muffler. Exciter, 6a is a noise detector, 6b is an amplifier, 6c is a sound pressure frequency analyzer, 6d is a phase inverter, 6e is a vibration intensity / frequency adjuster, 6f is a vibration generator, 6g is a vibration sound detector, 6h is an amplifier, 6i is a sound pressure frequency analyzer, 6k is a comparator, 9 is an air outlet, 10 is an air inlet, and 11 is exhaust gas output. , 12 is a fuel gas inlet, 13 is a low temperature water inlet, 14 is a high temperature water outlet, 15 is an exhaust pipe, 16 is a cooling fan, 17 is a compressor, 18 is a generator, 19 is a turbine, 20 is a regenerator, 21 is A regenerator casing, 22 is an exhaust gas outlet, and 23 is a sound deadening box.

Claims (4)

By storing the noise source inside the box, and providing a sound deadening vibration device equipped with a noise detector on the wall plate of the box, by vibrating the wall plate of the box by the sound deadening vibration device, The noise detector has a sound pressure frequency distribution similar to the sound pressure frequency distribution of the noise detected by the noise detector and generates a noise-canceling vibration sound having a phase difference of 180 °, and the noise generated from the noise source by the noise-canceling vibration sound is generated. A noise reduction method characterized by canceling out. Claim 1 wherein the box body is a box body having a thin metal wall plate on the four sides and the ceiling, and wherein a vibrating device for noise reduction provided with a noise detector is provided on each of the four surrounding wall plates of the box body. Noise reduction method as described. A box is formed from a support frame and a thin metal wall plate supported and fixed to the support frame, and the wall plate is supported and fixed to the support frame via an exciter having elasticity. 2. The method for reducing noise according to 1. 2. The noise reduction method according to claim 1, wherein the silencing vibration sound generated by the silencing vibration device has a peak sound pressure having a frequency substantially equal to the peak sound pressure in the sound pressure frequency distribution of the noise.

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