JPH05196225A - Silencer for exhaust air duct - Google Patents

Abstract

PURPOSE:To obtain a noise elimination device for an exhaust duct in a compact incinerator which is capable of complying with any changes in noise characteristics with ease and minimizing pressure loss in the duct. CONSTITUTION:There are provided a noise detection sensor 8 arranged on the upper stream side of an exhaust duct 2, an additional sound speaker 5 arranged on the downstream side of the noise detection sensor 8 and a remaining sound detection sensor 6 disposed on the downstream side of the additional sound speaker 5. There is also provided a noise elimination controller 7 which generates a reverse phase noise elimination acoustic wave at an acoustic level equivalent to detected noise in the exhaust air duct 2 by driving the additional sound speaker 5 based on a detected value by the noise detection sensor 8 and corrects the noise elimination acoustic wave based on a detected vague by the remaining sound detection sensor 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler for an exhaust duct for preventing exhaust noise in urban areas.

[0002]

2. Description of the Related Art Conventionally, in a muffler provided in an exhaust duct of a refuse incinerator, for example, a muffler such as a sound absorbing type, an expansion type or a resonance type is generally interposed in the exhaust duct. It was

[0003]

However, since the muffler is designed to correspond to the generated sound source, it cannot be easily dealt with when the noise characteristics of the sound source change, and the noise reduction is low. There is a problem that the volume of the muffler becomes large for the noise of the frequency and the pressure loss in the duct becomes large.

The present invention solves the above problems and provides a muffler for an exhaust duct which can easily cope with a change in the generated sound pressure characteristic, has a small pressure loss in the duct, and can be constructed compactly. The purpose is to

[0005]

In order to solve the above-mentioned problems, a muffler for an exhaust duct according to the present invention is provided with noise detecting means arranged upstream of the exhaust duct and downstream of the noise detecting means. The additional sound speaker and the residual sound detecting means arranged on the downstream side of the additional sound speaker are provided, and the additional sound speaker is activated based on the detection value of the noise detecting means to generate the same sound pressure level as the detected noise. In addition, a sound deadening sound wave having an opposite phase is generated in the exhaust duct, and a sound deadening controller is provided to correct the sound deadening sound wave based on the detection value of the residual sound detecting means.

[0006]

According to the above construction, the sound wave for silencing having the same sound pressure level as the detected noise detected by the noise detecting means and having the opposite phase,
Since it is corrected by the detection value of the residual sound detection means and generated by the additional sound speaker, it interferes with the noise and mutes,
Even if the noise characteristics change, it can be easily dealt with, and the sensors and speakers installed in the duct can also extremely reduce the flow path resistance, so the pressure loss in the duct can be extremely reduced. The whole can be made compact.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a muffler for an exhaust duct according to the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a basic block diagram of this silencer.
It shows a silencer that can be added to a general exhaust duct of a factory or a device. That is, a blower rotation sensor (an example of noise detection means) 4 for detecting the rotation speed of the drive motor 3 of the exhaust blower 1 is attached to the exhaust duct 2 in the middle of which an exhaust blower 1 is interposed, A discharge port 2b is provided in the vicinity of a corner 2d between the intermediate duct 2a on the downstream side of the blower 1 and the downstream duct 2c reaching the exhaust port 2b.
An additional sound speaker 5 having a sound pressure generating surface facing the side is provided. Further, a residual sound detection sensor 6 is arranged in the downstream exhaust duct 2c on the downstream side of the additional sound speaker 5.

Reference numeral 7 is a muffling controller in which the sound pressure level and the sound wave waveform of the noise generated according to the number of rotations of the drive motor 3 of the exhaust blower 1 are stored in advance, and depending on the detected value of the blower rotation sensor 4. Based on the stored value, a sound wave for silencing having the same sound pressure level as the generated noise but having an opposite phase is added to the speaker 5 for additional sound.
It is possible to correct the output signal based on the detection value of the residual sound detection sensor 6 while outputting the signal to be generated.

Reference numeral 8 denotes a noise detection sensor (an example of noise detection means) provided in the intermediate duct 2a, which detects exhaust noise and inputs it to the muffling controller 7, and based on the detected value, the same sound pressure level as the generated noise. Thus, it is possible to output a signal for causing the additional sound speaker 5 to generate a sound wave for silencing that has an opposite phase.
The noise detection sensor 8 can be provided independently in place of the rotation sensor 4 and can function, or can be provided together with the rotation sensor 4 to selectively function, and one of them can be used as an auxiliary device in case of failure of the other. It can also be used for.

FIG. 2 shows a concrete embodiment provided in an exhaust duct for exhaust gas containing heat, dust, dust, etc., such as an exhaust duct of a refuse incineration facility.
That is, the noise detection section of the intermediate exhaust duct 2a is connected to the noise propagation pipe 11 in a direction orthogonal to the intermediate exhaust duct 2a, and the noise detection sensor 8 is provided at the tip thereof. Then, the first cooling gas pipe 1 for feeding the cooling air of the noise detection sensor 8 to the tip of the noise propagation pipe 11
2 is connected, and a first heat insulating material 13 that can prevent dust and dirt from entering the exhaust gas without attenuating the noise sound pressure is provided in the middle portion of the noise propagation pipe 11.

Further, an additional sound propagation pipe 14 is connected to the corner portion 2d of the exhaust duct 2 in a direction continuous with the downstream exhaust duct 2c, and a speaker 5 for additional sound is provided at the tip portion thereof. The second cooling gas pipe 15 for feeding the cooling air of the additional sound speaker 5 to the tip of the noise propagation pipe 11 is connected to a plurality of locations around the additional sound speaker 5, and the additional sound is propagated. A second heat insulating material 16 that can prevent dust and dirt from entering the exhaust gas without damaging the added sound pressure is provided in the middle portion of the pipe 14.

Further, a residual sound detecting pipe of the downstream exhaust duct 2c is connected with a residual sound propagating pipe 17 which is bent in the vicinity of the connecting portion toward the upstream side in parallel with the downstream exhaust duct 2a. A sensor 6 is provided. A third cooling gas pipe 18 for feeding cooling air of the residual sound detecting sensor 6 is connected to the tip of the residual sound propagation pipe 17, and the residual sound sound is transmitted to the middle part of the residual sound propagation pipe 11. A third heat insulating material 19 is provided which can prevent dust and dirt from entering the exhaust gas without attenuating the pressure.

According to the above configuration, the first and third heat insulating materials 1
By providing the noise detection sensor 8 and the residual sound detection sensor 6 via the noise propagation pipe 11 and the residual sound propagation pipe 17 with the 3, 3 interposed, respectively, the wind noise and the airflow noise generated in the sensor unit are minimized. It is possible to accurately and accurately detect the waveform or sound pressure level of noise or residual sound. Further, by providing the additional sound speaker 5 via the additional sound propagation tube 14 with the second heat insulating material 16 interposed, it is possible to prevent the exhaust gas from directly contacting the exhaust gas, and
To positively cool with cooling air supplied from the third cooling gas pipes 12, 15, and 18 to prevent the noise detection sensor 8, the residual sound detection sensor 6, and the additional sound speaker 5 from being damaged by heat. You can Therefore, the noise of the exhaust gas duct 2 for the exhaust gas of the refuse incineration facility including dust and dirt at high temperature can be effectively attenuated with almost no pressure loss, and particularly the low frequency noise is effectively attenuated with a compact configuration. be able to.

[0015]

As described above, according to the muffler of the exhaust gas duct of the present invention, the residual sound detecting means generates the sound absorbing sound wave having the same magnitude as the detected noise detected by the noise detecting means and having the opposite phase. It is corrected by the detected value of the noise and generated by the speaker for additional sound, and it interferes with the noise to mute the sound, so it can easily respond even if the noise sound source changes, and the sensors and speakers installed in the duct also play. Since the road resistance can be extremely reduced, the pressure loss in the duct can be extremely reduced, and the entire structure can be made compact.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing an embodiment of a muffler for an exhaust gas duct according to the present invention.

FIG. 2 is a specific configuration diagram when the muffler is adopted in an exhaust gas duct of a dust incinerator.

[Explanation of symbols]

 1 Exhaust Blower 2 Exhaust Duct 3 Drive Motor 4 Blower Rotation Sensor 5 Speaker for Additional Sound 6 Residual Sound Detection Sensor 7 Noise Reduction Controller 8 Noise Detection Sensor 11 Noise Propagation Pipe 14 Additional Sound Propagation Pipe 17

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[Procedure amendment]

[Submission date] June 30, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

[Title of the Invention] A silencer for an exhaust duct in a refuse incinerator

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler for an exhaust duct in a refuse incinerator having a muffler for reducing exhaust noise.

[0002]

2. Description of the Related Art Conventionally, a muffler provided in an exhaust duct of a refuse incinerator has a sound absorbing type and an expanding type in the exhaust duct.
It was common to interpose a muffler such as a resonance type.

[0003]

However, since the muffler is designed to correspond to the generated sound source, it cannot be easily dealt with when the noise characteristics of the sound source change, and the noise reduction is low. There is a problem that the volume of the muffler becomes large for the noise of the frequency and the pressure loss in the duct becomes large.

The present invention solves the above problems and can easily cope with a change in generated sound pressure characteristics, and also has a small pressure loss in the duct, which is compact in size and can be constructed in a compact manner. The purpose is to provide a device.

[0005]

In order to solve the above-mentioned problems, a muffler for an exhaust duct in a refuse incinerator according to the present invention comprises a noise detecting means disposed upstream of an exhaust duct at an intermediate portion of the exhaust duct. A speaker for additional sound arranged on the downstream side of the detecting means, a residual sound detecting means arranged on the downstream side of the speaker for additional sound, and an operation for detecting the additional sound speaker based on the detection value of the noise detecting means. A muffling device is provided which includes a muffling sound wave having the same sound pressure level as the noise and having an opposite phase in the exhaust duct, and a muffling controller that corrects the muffling sound wave based on the detection value of the residual sound detecting means. It is a thing.

[0006]

According to the above construction, the sound wave for silencing having the same sound pressure level as the detected noise detected by the noise detecting means and having the opposite phase,
Since it is corrected by the detection value of the residual sound detection means and generated by the additional sound speaker, it interferes with the noise and mutes,
Even if noise characteristics change due to changes in the load of the refuse incinerator, it is possible to easily cope with it, and the sensors and speakers installed in the exhaust duct can also have extremely low flow resistance, so The pressure loss can be extremely reduced, and the entire structure can be made compact.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a silencer for an exhaust duct in a refuse incinerator according to the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a basic configuration diagram of an exhaust duct equipped with a muffler. That is, the exhaust blower 1
A blower rotation sensor (an example of noise detecting means) 4 for detecting the rotation speed of the drive motor 3 of the exhaust blower 1 is attached to the exhaust duct 2 in which
Exhaust blower 1 Intermediate exhaust duct 2a and exhaust port 2 on the downstream side
A speaker 5 for additional sound having a sound pressure generating surface facing the exhaust port 2b is disposed in the vicinity of a corner portion 2d with the downstream exhaust duct 2c reaching b. Also, a speaker for additional sound 5
The residual sound detection sensor 6 is disposed in the downstream exhaust duct 2c on the downstream side of the.

Reference numeral 7 is a muffling controller in which the sound pressure level and the sound wave waveform of the noise generated according to the number of rotations of the drive motor 3 of the exhaust blower 1 are stored in advance, and depending on the detected value of the blower rotation sensor 4. Based on the stored value, a sound wave for silencing having the same sound pressure level as the generated noise but having an opposite phase is added to the speaker 5 for additional sound.
It is possible to correct the output signal based on the detection value of the residual sound detection sensor 6 while outputting the signal to be generated.

Reference numeral 8 denotes a noise detecting sensor (an example of noise detecting means) provided in the intermediate exhaust duct 2a, which detects exhaust noise and inputs it to the muffling controller 7, and based on the detected value, the same sound pressure as the generated noise. It is possible to output a signal for causing the additional sound speaker 5 to generate a sound wave for silencing having a phase opposite to that of the level. This noise detection sensor 8 is a blower rotation sensor 4
In place of the above, it can be provided independently and can function, or it can be provided together with the blower rotation sensor 4 so as to selectively function, and it is also possible to use one of them as an auxiliary when the other fails. .

FIG. 2 shows a concrete embodiment of an exhaust duct equipped with a muffler for countermeasures against exhaust gas containing dust and dirt at high temperatures. That is, the intermediate exhaust duct 2a
The noise propagation section 11 is connected to the noise propagation pipe 11 in a direction orthogonal to the intermediate exhaust duct 2a, and the noise detection sensor 8 is provided at the tip thereof. And this noise propagation pipe 1
The first cooling gas pipe 12 for feeding the cooling air of the noise detection sensor 8 is connected to the tip of the noise detection sensor 8, and the dust in the exhaust gas is attenuated in the middle of the noise propagation pipe 11 without attenuating the noise sound pressure. A first heat insulating material 13 that can prevent the entry of dust is provided.

Further, an additional sound propagation pipe 14 is connected to the corner portion 2d of the exhaust duct 2 in a direction continuous with the downstream exhaust duct 2c, and a speaker 5 for additional sound is provided at the tip portion thereof. The second cooling gas pipe 15 for feeding the cooling air of the additional sound speaker 5 to the tip of the noise propagation pipe 11 is connected to a plurality of locations around the additional sound speaker 5, and the additional sound is propagated. A second heat insulating material 16 that can prevent dust and dirt from entering the exhaust gas without damaging the added sound pressure is provided in the middle of the pipe 14.

Further, a residual sound detecting pipe of the downstream exhaust duct 2c is connected to a residual sound propagating pipe 17 which is bent in the vicinity of the connecting portion in parallel with the downstream exhaust duct 2c on the upstream side, and the residual sound is detected at the tip thereof. A sensor 6 is provided. A third cooling gas pipe 18 for feeding cooling air of the residual sound detecting sensor 6 is connected to the tip of the residual sound propagating pipe 17, and the residual sound propagating pipe 17 has an intermediate part. A third heat insulating material 19 is provided which can prevent dust and dirt from entering the exhaust gas without attenuating the pressure.

According to the above configuration, the first and third heat insulating materials 1
By providing the noise detection sensor 8 and the residual sound detection sensor 6 via the noise propagation pipe 11 and the residual sound propagation pipe 17 with the 3, 3 interposed, respectively, the wind noise and the airflow noise generated in the sensor unit are minimized. It is possible to accurately and accurately detect the waveform or sound pressure level of noise or residual sound. In addition, by providing the additional sound speaker 5 via the additional sound propagation tube 14 with the second heat insulating material 16 interposed, direct contact with exhaust gas is prevented and
To positively cool with cooling air supplied from the third cooling gas pipes 12, 15, and 18 to prevent the noise detection sensor 8, the residual sound detection sensor 6, and the additional sound speaker 5 from being damaged by heat. You can Therefore, the noise of the exhaust duct 2 for the exhaust gas of the refuse incineration facility containing dust and dirt at a high temperature can be effectively damped with almost no pressure loss, and particularly the low frequency noise is effectively damped with a compact structure. be able to.

[0015]

As described above, according to the muffler for the exhaust duct in the refuse incinerator of the present invention, the muffler eliminates noise in the opposite phase with the same sound pressure as the noise detected by the noise detecting means. The sound wave for use is corrected by the detection value of the residual sound detecting means and generated by the speaker for additional sound, and it interferes with the noise to mute the sound, so it is easy even if the noise source changes significantly due to fluctuations in the load of the incinerator. Since it is possible to correspond to, and the flow resistance of sensors and speakers installed in the exhaust duct can be extremely reduced,
The pressure loss in the duct can be extremely reduced, and the entire structure can be made compact.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing an embodiment of a muffler for an exhaust duct in a refuse incinerator according to the present invention.

FIG. 2 is a specific configuration diagram of a silencer for an exhaust duct in the same refuse incinerator.

[Explanation of symbols] 1 exhaust blower 2 exhaust duct 3 drive motor 4 blower rotation sensor 5 speaker for additional sound 6 residual sound detection sensor 7 muffling controller 8 noise detection sensor 11 noise propagation tube 14 additional sound propagation tube 17 residual sound propagation tube

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Kato 5-3-3, Nishikujo 5-chome, Konohana-ku, Osaka City, Osaka Prefecture Hitachi Shipbuilding Co., Ltd.

Claims (1)

[Claims] 1. A noise detecting means arranged upstream of the exhaust duct, a speaker for additional sound arranged downstream of the noise detecting means, and a residual sound detecting means arranged downstream of the speaker for additional sound. Based on the detection value of the noise detecting means, the additional sound speaker is operated to generate a sound wave for silencing in the exhaust duct at the same sound pressure level as the detected noise but in the opposite phase, and the residual sound detecting means detects it. A muffler for an exhaust duct, comprising a muffling controller for correcting the muffling sound wave based on a value.