JPH04262191A - Low noise type pressure reduction structure - Google Patents

Abstract

PURPOSE:To make the reduction structure compact in size and improve the anti-erosion performance of the porous metal member in a low noise type multi- stage reduction device provided to a pressure reducing piping system for an ultra-high pressure fluid. CONSTITUTION:At a position immediately after an orifice plate 3 is mounted at a very small gap therefrom a multi-orifice plate 8 having a larger opening area than the orifice plate 3. After the location of the multi-orifice plate 8 are mounted a porous metal member 7 and a porous retainer plate 9. With this arrangement, the pressure reduction structure is made compact in size. Further, by having disposed the porous metal member 7 at a sufficiently pressure reduced position downstream of the multi-orifice plate 8, the porous metal member per se is protected from erosion.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a low-noise multi-stage decompression device that is applied to ultra-high pressure liquid/gas depressurization piping systems such as drain piping, gas discharge piping, and air blowing piping in thermal power plants and chemical plants. Regarding low noise pressure reduction structure.

0002

[Prior Art] As shown in FIG. 6, the conventional pressure reduction structure in piping is such that a single-hole orifice plate 3 is sandwiched between a flange 2 in the middle of a pressure-reduction pipe 1, and the opening ratio of the single-hole orifice plate 3 is adjusted according to the amount of pressure reduction. I try to choose accordingly.

Furthermore, when the required amount of pressure reduction cannot be obtained in one step, such as when applying ultra-high pressure, the single-hole orifice plate 3 is moved by spacers 4 in the fluid flow direction, as shown in FIG.
There are many depressurizing structures that are installed in multiple stages. Since the above-described pressure reduction structure is designed solely for the purpose of pressure reduction, there is a problem in that cavitation noise is generated due to pressure reduction, or intense noise is generated due to shock waves.

Therefore, the present inventors developed a multi-hole orifice plate 5, 6 having a large number of holes as a resistor as shown in FIG.
By making the combination of a porous metal 7 with very low resistance and high porosity for rectifying high-speed flow into multiple stages, 1
By reducing the pressure difference between each stage and by supporting the porous metal surface with the next-stage porous orifice plates 5 and 6 by creating a multi-stage structure, it is possible to increase the strength of the member and simplify the structure. We proposed a low-noise, multi-stage decompression structure that prevents over-expansion of the flow and has a mechanism for reducing pressure and preventing the generation of shock waves.

[0005]

[Problems to be Solved by the Invention] Due to the ultra-high pressure that has come with recent advancements in technology, in the low-noise multi-stage decompression structure shown in Fig. 8, the number of stages increases as the applied pressure difference increases. There are space problems due to the increased dimensions. In addition, due to the high-speed flow at the orifice hole exit,
Since there is a risk of wear due to erosion of the porous metal itself, there are problems in terms of strength when dealing with ultra-high pressures. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a low-noise pressure reduction structure that eliminates such problems.

[0006]

[Means for Solving the Problems] According to the present invention, a porous orifice plate having a larger opening area than the orifice plate is installed immediately after the orifice plate at a minute interval, and a porous metal is installed after that. Then, the distance between the orifice plate and the porous orifice plate is set to 0.3 to 0.6 of the orifice hole diameter.
By doubling the size, the shock wave generation position is fixed between the orifice plates and the generation of large shock waves is prevented. Further, according to the present invention, the holes in the orifice plate and the holes in the porous orifice plate are arranged radially apart at positions where they cannot be seen from each other.
In addition, it is opened at a position where the pressure is reduced downstream of the shock wave to avoid erosion of the porous metal itself due to high-speed flow.

[0007]

[Operation] According to the above means, the fluid flowing through the pressure reduction piping system first generates noise due to shock waves when it passes through the hole in the orifice plate of the low noise pressure reduction structure, but the shock waves are sandwiched between the two orifices. This suppresses the generation of loud noise. Additionally, the porous metal rectifies fluid flow and prevents noise generation.

[0008]

[Example] Fig. 1 shows an example of a pressure reducing device to which the present invention is applied.
This is explained by: In FIG. 1, the same parts as shown in FIG. 8 are given the same reference numerals.

In FIG. 1, the porous orifice plate 8 is located immediately behind and adjacent to the orifice plate 3. As shown in FIG. A porous metal 7 filled in the spacer 4 is disposed downstream of the spacer 4.
is arranged and further fixed to the flange 2 of the downstream piping 1 via the holding porous plate 9. The high-pressure fluid is flowing inside the decompression pipe 1 in the direction of the arrow, and expands under reduced pressure when passing through the hole in the orifice plate 3.
The generated shock wave is caused by the orifice plate 3 and the porous orifice plate 8.
It will be restrained by the part sandwiched between the two orifices. Therefore, a large shock wave cannot be formed in that portion, thereby preventing the generation of strong and large vortices and turbulence of the fluid that cause noise generation. In this way, the ultra-high pressure fluid is depressurized by the orifice plate 3 and the porous orifice plate 8 with low noise, but when it passes through the holes of the porous orifice plate 8, the fluid is similarly depressurized and expanded. Generates noise. In contrast, the large vortices and turbulence of the ultra-high pressure fluid are rectified by the spongy three-dimensionally fine mesh-like skeleton of the porous metal 7 placed immediately after the porous metal 7, and the porous orifice plate 8 is rectified. This prevents noise from being generated in the holes.

Furthermore, the ultra-high pressure fluid is reduced in pressure by the orifice plate 3 and the porous orifice plate 8 to a pressure at which the porous metal has sufficient strength, and the final pressure reduction and noise reduction are applied to the porous metal. As a result, the low-noise decompression structure itself can be made compact, and the erosion resistance performance can be greatly improved.

Here, regarding the relationship between the distance h between the orifice plate 3 and the porous orifice plate 8 and the orifice hole diameter d,
As a result of testing a large number of specimens produced with different ratios h/d, it was found that the distance h between the orifice plate 3 and the porous orifice plate 8 was particularly within the range of 0.3 to 0.6 times the orifice hole diameter d. It was found that the low-noise decompression effect is significant.

FIGS. 2 to 4 are views of the orifice plate 3, the porous orifice plate 8, and the holding porous plate 9, respectively, as viewed from the fluid flow direction. The holes in the orifice plate 3 in FIG. 2 are radially separated from the holes in the porous orifice plate 8 and are formed in a staggered arrangement so that they cannot be seen from each other. It is blocked by the plate part of plate 8. Therefore, since a high-speed flow does not directly act on the porous metal 7 on the downstream side, the problem of erosion of the porous metal 7 is avoided. As shown in FIG. 4, the holding porous plate 9 that holds the porous metal 7 has openings sufficient to prevent the occurrence of fluid eddies and turbulence.

FIG. 5 shows an example of noise reduction when superheated steam whose upstream pressure is 10 MPa or more is reduced to atmospheric pressure. According to FIG. 5, in the case of the low-noise pressure reduction structure according to the present invention, a sound reduction effect of 30 dBA or more was obtained, and there was no damage to the porous metal. In this case, the flow rate was There is no difference from the case where the pressure is reduced using only the orifice plate, and it can be seen that the present invention is a very effective pressure reduction structure that can significantly reduce only the generated sound without affecting the flow rate and pressure reduction characteristics.

[0014]

[Effects of the Invention] According to the present invention, as shown in FIG.
In the low-noise multi-stage depressurization structure shown in Figure 1, the number of stages increases as the pressure difference increases due to ultra-high pressure, resulting in space-related problems such as lengthening of the dimensions, and high-speed flow at the high-outlet part of the orifice. There was a risk of wear due to erosion of the porous metal itself, but in the present invention, ultra-high pressure fluid is
By using two orifice plates, the pressure is reduced to a pressure where the porous metal has sufficient strength, and the porous metal is responsible for the final pressure reduction and noise reduction, which greatly improves compactness and erosion resistance. It was done. In the pressure reduction structure according to the present invention, the flow is always choked at the upstream orifice, so the flow rate characteristics are no different from those in the case of pressure reduction using one orifice stage.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a low-noise multi-stage pressure reduction device implementing a low-noise pressure reduction structure according to the present invention.

FIG. 2 is a front view of the orifice plate shown in FIG. 1.

FIG. 3 is a front view of the porous orifice plate shown in FIG. 1;

4 is a front view of the holding porous plate shown in FIG. 1. FIG.

FIG. 5 is an explanatory diagram showing pressure reduction and sound reduction performance according to an example of the present invention.

FIG. 6 is a longitudinal cross-sectional view showing a conventional orifice single-stage decompression device.

FIG. 7 is a longitudinal cross-sectional view showing a conventional orifice multi-stage decompression device.

Fig. 8 shows a conventional low-noise multi-stage decompression structure (a
) is a longitudinal sectional view thereof, and (b) is the upstream side porous orifice plate 8.
(c) is a front view of the downstream porous orifice.

[Explanation of symbols]

1 Piping 2 Flange 3 Orifice plate 4 Spacer 5 Upstream porous orifice plate 6 Downstream side porous orifice plate 7 Porous metal plate 8 Porous orifice plate 9 Porous plate for holding

Claims (3)

[Claims] 1. A low-noise decompression structure comprising a porous orifice plate having a larger opening area than the orifice plate installed at a small distance immediately behind the orifice plate, followed by a porous metal. Claim 2: Claim 1, wherein the distance between the orifice plate and the porous orifice plate is 0.3 to 0.6 times the orifice hole diameter.
Low noise decompression structure as described. 3. The low-noise pressure reducing structure according to claim 1, wherein the holes in the orifice plate and the holes in the porous orifice plate are arranged in a staggered manner so that the holes cannot be seen from each other.