JP2601877B2 - Heat resistant silencer - Google Patents

Description

The present invention relates to a heat-resistant silencer, and particularly to a gas turbine,
It relates to a heat-resisting silencer which can be advantageously used as an exhaust silencer for a jet engine, a silencer for a steam turbine, a silencer for a fan (suction fan for a boiler and a push-in fan), a soundproof wall including a road and a tunnel, and a wall material of a building. is there.

[Conventional technology]

Conventionally, exhaust silencers for gas turbines use glass wool, which is a sound-absorbing material having excellent sound-absorbing properties for high-frequency sounds, in the form of a fourth.
This is stored in a box 1 as shown in FIG. In this case, the structure shown in FIG. 4 (b), which is a cross-sectional view of FIG. 4 (a), has a perforated plate 3 on the wall material of the box 1 so that the glass wool 2 in the box 1 is not scattered. , A fine stainless steel wire mesh or foam metal 4 is installed inside, and Al ₂ O ₃ or SiO _2
The glass wool (the material is almost the same as the ceramic cloth) 2 is wrapped by a ceramic cloth 5 mainly composed of ₂ .

However, in the above configuration, since the ceramic cloth 5 is hard and brittle, the ceramic cloth 5 is easily torn by rubbing the ceramic cloth 5 with the stainless steel wire mesh or the foamed metal 4, and the inner glass wool 2 is broken. It passes through the stainless steel wire mesh or the foamed metal 4 and flows out to the outside, and the sound absorbing properties are impaired. Further, since the metal net made of stainless steel or the foamed metal 4 does not have a sound absorbing property, there is a problem that sound of about 1000 Hz or less which cannot be sufficiently absorbed by the glass wool 2 alone cannot be absorbed.

4 (c), which is a cross-sectional view of another embodiment of FIG. 4 (a), comprises a sintered sound absorbing material 6 of aluminum powder having a sound absorbing property for the wall material of the box 1. However, this sintered sound absorbing material 6 (see Japanese Patent Publication No. 56-11375) does not have heat resistance, and cannot be used for a long time in a high temperature range of 500 to 600 ° C., such as an exhaust silencer for a gas turbine. There is a problem that is possible. In FIG. 4 (c), reference numeral 7 denotes a support frame for the aluminum powder sintered sound absorbing material 6.

Further, when a ceramics sound absorbing material such as mullite or shamot is used for the wall material having the structure shown in FIG. 4 (c), the ceramics are hard and brittle, and the box 1
Because the thermal expansion difference between the support frame 7 and the metal (low alloy steel or stainless steel) is large, (the coefficient of thermal expansion of the metal: 12 to 18 × 1
0 ^-6 / ° C, coefficient of thermal expansion of ceramics: 4-5 × 10 ^-6 / ° C)
When used at high temperatures, there is a problem that the design of the support structure requires some contrivance and is difficult to handle.

Therefore, a high-frequency sound of about 1000 Hz or more is absorbed by heat-resistant fibers such as glass wool, and a low-frequency sound of about 1000 Hz or less is absorbed by the wall material, and a siren that does not scatter the heat-resistant fiber filled inside the wall material is used. In order to achieve this, it is necessary to develop a porous sound-absorbing material that functions as a wall material even at high temperatures such as 500-600 ° C, has excellent sound-absorbing properties for low-frequency sound, and does not transmit and scatter heat-resistant fibers. Atsuta.

[Problems to be solved by the invention]

In a sound absorbing material, a transmission hole must be formed three-dimensionally between powder particles. The passages are long because the holes that exist and connect innumerably continuously in the sound absorbing material become irregular, and the sound entering from the surface does not go straight as it is, The sound energy is converted into heat energy through the through holes, and the wave energy of the sound must be attenuated. Especially in gas turbine exhaust silencers, low-frequency sound is a problem, so it is necessary to have excellent characteristics to absorb low-frequency sound. The sound wave energy is converted to heat energy by the viscosity of the existing air. For that purpose, it is necessary to adjust the particle size as a powder having an optimum particle size.

Further, since high-frequency sound is difficult to absorb with a sintered metal, it is necessary to use heat-resistant fibers such as rock wool, and the transmission holes must have a size that does not allow the internal heat-resistant fibers to pass through. Heat-resistant fibers such as rock wool are originally used in the form of long fibers.
m, if the transmission hole of the wall material of the sound-absorbing material is large, there is a possibility that high-frequency sound as a silencer may not be absorbed as the silencer penetrates the hole and scatters and disappears to the outside. For this reason, the wall of the sound absorbing material must have a size such that the damaged heat-resistant fiber does not penetrate and disappear.

An object of the present invention is to provide a technique capable of providing a heat-resistant silencer that is excellent in high-temperature corrosion resistance and sound absorption and can absorb a wide range of noises from high-frequency sound to low-frequency sound in response to the above demands.

[Means for solving the problem]

The present inventors have confirmed that even if the grain size of the wall material of the sound absorbing material is too small, it is not necessarily excellent in sound absorbing properties.
We found that the wall material made of sintered metal with a particle size in the range of 0 to 12 mesh has excellent sound absorption and pores that do not dissipate and dissipate heat-resistant fibers. In addition, stainless steel grains contain 10% Cr as metal grains. Since it contains the above, it was found that it was a preferable raw material because of its high temperature corrosion resistance.

That is, the present invention provides a steel box having at least one opening, and a sintering density of 3.30 g / cm for covering the opening of the box.
³ or less, the average particle size of the sintered metal is 50-500μm and the flow resistance is
10 ⁶ MKS-rayls / m or less stainless steel, 1000Hz
It is characterized by comprising a sintered metal sound-absorbing material having excellent low-frequency sound absorption and a heat-resistant fiber having excellent high-frequency sound absorption of 1000 Hz or more, which is filled in the box. Is a heat-resistant silencer.

The sintered density of the sintered metal sound absorbing material in the present invention is 3.30 g / cm.
³ or less, the average particle size of the sintered metal was 50 to 500 μm, and the flow resistance was set to 10 ⁶ MKS-rayls / m or less. It is a thing.

The stainless steel alloy powder used for producing the sintered metal sound absorbing material of the present invention has a particle size range of 250 mesh (63 mm).
μm) to 12 mesh (1410 μm) because the average particle diameter of the sintered metal of the sintered metal sound absorbing material is 50 to 500 μm as a result of using the particles having the above particle size range. Further, it is not necessary to apply a pressing force at the time of sintering, but applying a slight pressure, for example, a pressure of 0.5 kg / cm ² or less is not hindered.

[Example 1] Using 12% Cr stainless steel having the chemical composition shown in Table 1,
An alloy powder having a particle size (a) shown in Table 2 was produced.
These powders were slightly pressed (approximately 1 kg at 300 mm x 300 mm) and sintered at about 1,200 ° C in a reducing atmosphere. The schematic diagram of Fig. 1 (a microscopic photograph of a 50x magnification)
As shown in Fig. 5, a porous sintered sound absorber having a structure of about 4 mm in thickness was manufactured. The sintered density and porosity of the sintered sound absorbers are as shown in (b) and (c) of Table 2.

With respect to these sintered sound absorbers, a rock wool having a thickness of 100 mm was put in the rear, and the results of (i) measurement of the normal incidence sound absorption coefficient according to JIS A1405-1963 are shown in FIG.
The results of measuring the flow resistance by TM C-522-73 are shown in (d) of Table 2.

As is clear from FIG. 2, the normal incidence sound absorption coefficient in the range of 1/3 octave band center frequency 0 to 1000 Hz is:
It is excellent when the grain size is set to 12 meshes from 250 meshes, and the vertical incidence sound absorption coefficient in the 1/3 octave band center frequency range of 0 to 7 × 10 ³ Hz is 145 meshes (105 μm).
It was found to be superior to m) by 12 meshes.

Also, the flow resistance at this time is 8.3 × 10 ⁴ MKS-rayls / m, and it can be seen that excellent sound absorption characteristics are exhibited in the order of 10 ⁴ MKS-rayls / m or less.

When the sintering density is 3.32 g / cm ³ , the sound absorption characteristics are poor, and 3.30 g / c
It turns out that it is excellent at m ³ or less.

Example 2 A simulated test piece of an exhaust silencer as shown in FIG. 3 was manufactured using the sintered sound absorbing body manufactured in Example 1 above. This was assembled in a combustion test device, and the scattering of rock wool was examined.

 The test conditions at this time are as follows.

Gas temperature: 550-600 ° C Gas flow rate: 50-60 m / s Test time: 300 hours Rock wool: manufactured by Nichias Corporation. 80 kg / m ³ As a result, as shown in Table 2 (e), no scattering of rock wool was observed in any of the sintered sound absorbers. Despite the test at a high temperature, no corrosion was observed and the high-temperature corrosion resistance was good.

In the case of using an alloy powder having a particle size larger than 12 mesh, sintering could not be sufficiently performed, and a material that could be used as a sintered sound absorber could not be manufactured.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION This invention can absorb the noise from a high frequency sound to a low frequency sound by employ | adopting the said structure, has excellent heat resistance, and can provide the heat resistant silencer which does not scatter a heat resistant fiber. It became so. Therefore, the present invention can be advantageously applied to not only the exhaust silencer for gas turbine but also a silencer for steam turbine and fan and other soundproof walls.

[Brief description of the drawings]

FIG. 1 is a schematic view of the structure of a sintered metal sound absorbing material according to one embodiment of the present invention, FIG. 2 is a table showing measured values of the normal incidence sound absorption coefficient of one embodiment of the present invention, and FIG. FIG. 4 is a schematic view of a heat-resistant silencer according to an embodiment of the present invention, and FIG. 4 is a schematic view of a conventional exhaust silencer.

Continued on the front page (72) Inventor Keizo Tsukagoshi 2-1-1 Shinama, Araimachi, Takasago City, Hyogo Prefecture Inside the Takasago Works, Mitsubishi Heavy Industries, Ltd. (72) Inventor Hisakataka Kawai 2-1-1, Araimachi Shinama, Takasago-shi, Hyogo Mitsubishi Inside the Takasago Research Laboratory, Heavy Industries, Ltd. (56) References JP-A-50-91505 (JP, A) JP-B-56-11375 (JP, B2)

Claims (1)

(57) [Claims] 1. A steel box having at least one open side,
The sintering density covering the opening surface of the box body is 3.30 g / cm ³ or less, the average particle size of the sintered metal is 50 to 500 μm, and the flow resistance is 10 ⁶
A sintered metal sound absorbing material made of stainless steel of MKS-rayls / m or less and having an excellent absorption rate of low frequency sound of 1000 Hz or less, and an absorption rate of a high frequency sound of 1000 Hz or more filled inside the box body. A heat-resistant silencer comprising excellent heat-resistant fibers.