JPH068252Y2 - Diffuser for silencer - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a silencer applied to a steam release point such as a safety valve or blowdown of a thermal power plant. It can also be used as a silencer for nuclear power plants, chemical plants, machines, and the like.

[Conventional technology]

Fig. 4 shows an external view of a safety valve installed in a steam pipe of a thermal power plant and its silencer in a mounted state. 1 is a steam pipe, 2 is a safety valve, 3 is an exhaust pipe, and 4 is a silencer. When the internal pressure of the steam pipe 1 rises to the set pressure of the safety valve, the safety valve 2 operates and the internal steam is discharged through the exhaust pipe 3. A muffler 4 is provided at the outlet of the exhaust pipe to reduce the noise level when steam is released. FIG. 5 shows a cross-sectional view of a conventional silencer. 5 is a silencer body, 6 is a diffuser, 7
Is a sound absorbing body that constitutes the splitter section. The diffuser has a function of rectifying the steam flowing from the exhaust pipe 3, and the sound absorber 7 has a function of absorbing a sound generated when the steam is discharged.

[Problems to be solved by the invention] In the conventional silencer, a strong noise is generated because the flow chokes in the diffuser section, and a large amount of sound absorber is required to reduce this noise. It had the drawback of being shaped.

[Means for solving problems]

The present invention solves the above-mentioned problems, and a cylinder having a large number of holes, a porous metal material provided so as to cover the outer periphery of the cylinder, and the same metal as a holding plate for holding the porous metal material. It is composed of a plurality of narrow plate materials provided with a gap on the outer periphery of the material, and the thickness of the porous metal material is not less than twice the diameter of the holes provided in the cylinder, When a gas is ejected from a hole, the gas is caused to flow in the radial direction of the cylinder in the porous metal material to gradually expand and decelerate to mute the sound, and to release it from the gap of the narrow plate material to the outside. It is a dexterous diffuser.

[Action]

The flow of gas ejected from each of the holes of the cylinder having a large number of holes is gradually expanded and decelerated while passing through the porous metal material in the radial direction of the cylinder, and the diameter of the hole of the cylinder is increased. At the end of passing through the porous metal material having a thickness twice or more, the flow becomes sufficiently gentle. Thereafter, this gas is discharged to the outside through the gap between the narrow plate materials. In the process of expanding and decelerating the gas, the sound itself is muted and the noise is reduced.

〔Example〕

FIG. 1 is a sectional view of an embodiment of the diffuser of the present invention. Since the diffuser is symmetrical with respect to the central axis, only the left half is shown. Reference numeral 10 is a cylindrical perforated plate having an end plate-shaped lid on its top, and holes 11 having a diameter d are formed in the side surface thereof in a 60 ° staggered pattern with a constant pitch. Reference numeral 12 is a porous metal having communication holes, which is provided outside the porous plate 10. 1
A pressing plate 3 is made of a narrow plate material and is made of a porous metal 1
In order to hold 2 and prevent its scattering and to secure a gas discharge port, a plurality of gaps are provided between each other. d is the diameter of the hole 11, and t is the thickness of the porous metal 12. FIG. 2 is a sectional view taken along line AA in FIG.

The porous metal 12 is a foam metal, a mesh wire, a sintered metal, or the like. Specific examples of the material and manufacturing method of the foam metal are as follows.

(1) Material: Ni-Cr alloy (2) Pore diameter: 1 to 5 mm (3) Shape: A skeleton of about 0.5 mm entangled three-dimensionally in a mesh.

(4) Manufacturing method: Conductive treatment of urethane foam, plating Ni, burning urethane away, and then Cr alloying treatment.

(5) Porosity: 96% (6) Rigidity: Large (7) Heat resistance: Large Of course, the porous metal is not limited to the above, and materials such as SUS and ceramic may be used. It doesn't matter if it is made by the method of.

The basic dimensions of each part are to maximize the sound reduction effect.
It is designed based on the following three design criteria.

(1) The thickness t of the porous metal 12 is at least twice the diameter d of the holes 11 of the porous plate 10, that is, t ≧ 2d.

(2) The aperture ratio σ of the perforated plate 10 is 10% or less, that is, σ ≦ 10%, in order to reduce the interference between the flows of the respective holes. However, the aperture ratio σ is a substantial aperture ratio in which the curvature is corrected by the outer diameter of the porous metal 12.

(3) The outlet opening ratio of the porous metal 12 is limited by the holding plate 13 according to the required flow rate so that the outlet flow velocity V of the porous metal 12 becomes 200 m / s or less. That is, V ≦ 200 m / s.

By designing the basic dimensions of the diffuser part as described above, it is possible to obtain an economical diffuser with good sound reduction effect.

The thickness t of the porous metal 12 is set to obtain the optimum sound reduction effect.
It is necessary to make the thickness corresponding to the hole diameter d of the perforated plate 10. The thicker the thickness, the greater the sound reduction effect, but the diffuser portion becomes large, the cost increases, and it is uneconomical.

The aperture ratio σ of the perforated plate 10 needs to be suppressed in order to avoid interference between the flows of the respective holes, but if the aperture ratio is lowered too much, the size of the cylindrical perforated plate 10 becomes large, which is uneconomical.

Further, the outlet flow velocity V from the porous metal 12 needs to be lower than the flow velocity at which noise is generated at the outlet of the porous metal 12 so that noise is not generated. For this reason, it is necessary to limit the opening ratio of the porous metal 12 at the outlet by the holding plate 13 according to the required flow rate.

FIG. 3 shows the result of a steam flow test carried out to find the optimum standard size. The test results provided the design criteria described above.

With the diffuser dimensions as described above, the flow from the perforated plate 10 is ejected as a choked flow with severe turbulence accompanied by a shock wave, but since there is the porous metal 12 immediately thereafter,
The flow from each hole forms a conical flow without interfering with each other, gradually expands and decelerates while passing through the porous metal 12, and becomes a gentle flow at the outlet of the porous metal 12. For this reason, the conventional sound generated in the diffuser portion is significantly reduced, the necessary sound absorbers can be reduced, and the vapor discharge silencer can be downsized. If the muffler for discharging steam is made smaller and lighter, the manufacturing cost of the muffler can be reduced, and tangible and intangible ripple effects such as the weight reduction of the supporting steel frame and the rationalization of the installation work will be produced, resulting in great advantages. Become.

[Effect of device]

The conventional muffler for vapor discharge part generates a lot of noise from the diffuser part and requires a large amount of sound absorber to obtain the required volume reduction of the muffler.However, the porous metal diffuser of the optimum shape of the present invention is used. By providing it, it is possible to significantly reduce the sound generated by the diffuser portion, and to reduce the size and weight of the silencer.

[Brief description of drawings]

1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA of the above embodiment, FIG. 3 is an explanatory view of the above embodiment, and FIG.
FIG. 5 and FIG. 5 are explanatory views of the prior art. 1 ... Steam pipe, 2 ... Safety valve 3 ... Exhaust pipe, 4 ... Silencer 5 ... Silencer main body, 6 ... Diffuser 7 ... Sound absorber, 10 ... Cylindrical perforated plate 11 ... Hole, 12 ... Porous metal 13 ... Holding plate d ... Pore diameter, t ... Porous metal thickness

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Satoshi Fukatsu Satoshi Fukatsu 2-1-1, Niihama, Arai-cho, Takasago-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Takasago Research Institute (56) Reference JP-A-47-8826 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A cylinder having a large number of holes, a porous metal material provided so as to cover the outer circumference of the cylinder, and a holding plate for holding the porous metal material, provided with a gap being provided at the outer circumference of the metal material. And a thickness of the porous metal material is not less than twice the diameter of the hole provided in the cylinder, and when gas is ejected from each hole of the cylinder, A diffuser for a silencer, characterized in that a gas is caused to flow in the radial direction of the cylinder in the porous metal material to gradually expand and decelerate to mute the sound, and to be discharged to the outside through a gap between the narrow plate materials.