JP3024688B2 - Vacuum orifice for liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure reducing orifice and a pressure reducing plate inserted into a liquid flow path.

[0002]

2. Description of the Related Art Hitherto, when reducing the pressure of a fluid in a piping system for transporting a liquid, a pressure reducing valve or a pressure reducing orifice has been generally used. Among these, the pressure reducing valve is commercially available under the name of a low noise valve or the like, which is suitable for low noise. However, this is expensive, especially when a special material must be used in a piping system for transporting an ultra-low temperature liquid such as LNG, the pressure reducing valve becomes a special material and becomes more expensive. At present, it is rarely used for anything other than special purposes.

FIG. 5A is an explanatory diagram showing a conventional example of a pressure reducing device using an orifice, and FIG. 5B is an explanatory diagram showing the occurrence of cavitation when the pressure reduction by the orifice in FIG. 5A is large. is there. An orifice 2 is provided in the pipe 1, and the liquid flows in the arrow X direction. The liquid changes its flow as indicated by the arrow Y in the contraction portion that has passed through the orifice 2. The liquid pressure is at the position X before the orifice.
In _1, the pressure P ₁ is rapidly decompressed by the orifice 2, a number of vapor bubbles become saturated vapor pressure P _V of the liquid at the position X ₂ appears cavitation - Deployment occurs. Then the liquid is located X ₃ to position X ₄ to cavitation through - Deployment generation state continues, gradually the pressure gradually recovers. During pressure recovery from the position X _4, a large number of steam bubbles when collapsing a metal surface near the upper surface in the pipe, the impact pressure generated at that time erotic scraping metal surfaces - generating John (erosion).
Cavitation at high decompression causes continuous repeated generation and collapse of vapor bubbles, resulting in severe vibration and erosion.

A marsh paper (ASME, J. OF Basic Engineer)
ing, "Cavitation Effect on theDischarge Coefficie
nt of the Sharp-Edged Orifice Plate ”, March 196
0, Report of Tohoku University Institute of High Speed Mechanics (Currently, Institute of Fluid Science)
Vol. 14, No. 136, 127 "Influence of cavitation on in-pipe orifice" According to March, 1959, in the case of water, initial cavitation occurs when the cavitation coefficient is about 2.5.

As described above, when the pressure reduction is large, it is difficult to cope with a single orifice. Usually, a plurality of orifices and a specially-shaped multistage orifice adopted by a pump maker or the like are used, and slowly. A method of reducing the pressure is taken. Recently, expanded metal laminated pressure reducing units (Japanese Patent Application No. 56-32478 and Japanese Patent Application No.
Japanese Patent Application Laid-Open No. 63-140577) and a fluid pressure reducing plate which is a cone type porous plate (see Japanese Patent Application No. 63-140577).
Has been proposed.

[0006]

The above-mentioned conventional expanded metal laminated pressure reducing unit using a plurality of orifices is not economical, and a plurality of orifices may not be arranged depending on the piping space. There is
In addition, there is a problem that the expanded metal laminated pressure reducing unit used in a specially shaped multistage orifice or an LNG line is expensive and takes a long time to deliver. Also, the conventional porous pressure reducing plate for a fluid is a pressure reducing device in which a plurality of holes are formed in a curved portion and a bottom portion of a cone portion, which is a cone of a plate-like member, and is effective in preventing vibration, but forming a cone. Is not very easy, and the only effect of the cone is to change the flow path of the liquid, and it is not intended to cause the flow path of the liquid to collide at a single point.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a liquid decompression orifice using a member which can be easily formed and formed, and which can impinge a liquid flow at one point in a decompression device to more effectively prevent contraction. The purpose is to:

[0008]

According to the present invention, there is provided a decompression orifice for liquid according to the present invention, which comprises a flat plate portion made of a flat plate-like member and a flat plate portion made of a hemispherical shell-shaped plate member and having a cross section all around. It consists of a hemispherical shell that is closely connected to one side,
The flat plate portion has at least one through hole at a position corresponding to the spherical center of the hemispherical shell portion and opposed to an inner wall of the hemispherical shell portion, and the hemispherical shell portion is drilled toward the spherical center. Preferably, the flat plate portion is located at a position corresponding to the spherical center of the hemispherical shell portion, and has one through hole facing the inner wall of the hemispherical shell portion, and the periphery of the through hole. And a plurality of through holes facing the inner wall of the hemispherical shell.

[0009]

The liquid flowing in the pipe reaches the hemispherical shell of the decompression orifice for liquid disposed in the pipe, and passes through a plurality of through holes formed in the hemispherical shell into the hemispherical shell. Inflow,
The liquid flowing from each through-hole collides at a position corresponding to the spherical center of the hemispherical shell portion, is rectified by the through-hole formed in the flat plate portion, and flows out downstream.

[0010]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1A and 1B are front views showing a first embodiment of a liquid pressure reducing orifice according to the present invention.
FIG. 2 is a plan view showing the flat plate portion of the embodiment of FIG. 1; FIGS. 3A and 3B are enlarged front views of the hemispherical shell portion of the embodiment of FIG. 1; FIG.

The liquid pressure reducing orifice according to the present embodiment includes a flat plate portion 10 made of a metal material (eg, SUS304) and a hemispherical shell portion 20 spot-welded to the flat plate portion 10 by a welding portion 30. . The flat plate part 10 is a disk part 1 having a diameter D _3.
0 ₂ and the handle 1 welded to a part of the circumference of the disk 10 ₂
0 consists ₃ which, in the center of the disk portion 10 ₂ is opened a through hole of a diameter D _1. The hemispherical shell portion 20 is a plate-like member having a hemispherical shape, a cross section having a ring shape, and an outer edge having a diameter D ₂ . The through-hole 20 ₁ toward the spherical center C in the hemispherical shell portion 20 is bored a number. Hemisphere shell 2
_No. 0 is spot-welded to one surface of the flat plate portion 10 so that the outer periphery of the cross section is concentric with the through hole 101 of the flat plate portion 10. There are four to eight welds 30. Flat plate part 1
0 between the diameter D ₂ and the diameter D ₃ (see FIG. 2) are used to sandwiched by the flange during attachment to the pipe.

Accordingly, when the liquid decompression orifice of this embodiment is installed in the pipe, and the liquid flows in the direction of arrow A and reaches the hemispherical shell portion 20, the liquid flows into each of the through holes 2.
Through 0 ₁ flows into the hemispherical shell 20 toward the spherical center C,. Liquid that has flowed toward the spherical center C flows out through the through hole 10 ₁ without causing too much the contracted flow is rectified by the flat plate portion 10.

FIG. 4 is a plan view showing a flat plate portion 11 used in the second embodiment of the present invention. Diameter through holes 11 ₂ around the through-hole 11 ₁ in the center than the through-hole 11 ₁ of the disk portion has a plurality bored in the present embodiment. Contraction flow becomes more hardly occurs by the through-hole 11 _2.

In the above description, the material of the decompression orifice for liquid is metal, but plastic may be used for a liquid that does not cause a chemical change. Also, the flat plate portions 10 and 11
May be a single plate.

[0016]

【The invention's effect】 As described above, according to the present invention, the liquid flowing through the plurality of through-holes of the hemispherical shell portion is directed to the sphere center of the hemispherical shell portion, and then straightened by the flat plate portion to flow out of the through-hole of the flat plate portion. Accordingly, it is possible to reduce the pressure of the inflowing liquid without causing a large amount of contraction, and it is possible to facilitate the manufacture by making the liquid into a hemispherical shape.

[Brief description of the drawings]

FIG. 1 (a) is a first decompression orifice for liquid of the present invention.
It is a front view which shows Example of each. (B) is a YY sectional view showing a first embodiment of the liquid pressure reducing orifice of the present invention.

FIG. 2 is a plan view showing a flat plate portion of the embodiment of FIG.

FIG. 3A is an enlarged front view of a hemispherical shell portion of the embodiment of FIG. FIG. 2B is an enlarged cross-sectional view of the hemispherical shell portion of the embodiment in FIG.

FIG. 4 is a plan view showing a flat plate portion according to a second embodiment of the present invention.

FIG. 5A is an explanatory view showing a conventional example of a pressure reducing device using an orifice. (B) is an explanatory view showing the occurrence of cavitation when the pressure reduction by the orifice is large.

[Explanation of symbols]

10, 11 flat plate portion 10 ₁ , 11 ₁ , 11 ₂ , 20 ₁ through hole 10 ₂ disk portion 10 ₃ handle portion 20 hemispherical shell portion 30 point welded portion

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16L 55/00 F16L 55/04-55/045

Claims (2)

(57) [Claims] 1. A flat plate portion made of a flat plate-like member, and a hemispherical shell portion made of a hemispherical shell-shaped plate-like member and having a cross-section that is in close contact with one surface of the flat plate portion over the entire circumference. The flat plate portion has at least one through hole at a position corresponding to the spherical center of the hemispherical shell portion and facing the inner wall of the hemispherical shell portion, and the hemispherical shell portion faces toward the spherical center. A vacuum orifice for liquid having a plurality of perforated holes. 2. The flat plate portion is located at a position corresponding to the spherical center of the hemispherical shell portion and has one through hole facing the inner wall of the hemispherical shell portion.
The orifice according to claim 1, further comprising a plurality of through-holes formed around the through-hole and facing the inner wall of the hemispherical shell.