JPH06257687A - Valve device - Google Patents

Abstract

PURPOSE:To ensure the stable flow of a fluid through an orifice, enable the prevention of the occurrence of a whirling flow and cavitation, improve the durability of a valve itself and piping, and enable quiet operation to be realized with less noises. CONSTITUTION:A plurality of flow holes 23 of an orifice 22 laid between a seat ring 8 and a tail piece are arranged approximately along the same circumference having a center at the center of the orifice 22, and the open sections 23a of the holes 23 at the side of the seat ring 8 are formed to be cone type with roundness having a radius equal to 5 to 10 times of a flow hole diameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve device, and more particularly to an angle valve for controlling pressure reduction of a slurry fluid with a high differential pressure.

[0002]

2. Description of the Related Art Angle valves are generally used in a pressure reduction / control line for coal slurry in a coal liquefaction plant or a pressure reduction / control line for a solid-liquid two-phase flow containing various catalysts in a chemical plant. The angle valve has the advantage that the piping system can be designed compactly because the flow direction of the fluid can be bent at a right angle. However, if the angle valve is a valve that is excessively depressurized on the downstream side, a large amount of gas is generated in the over-depressurization section, and it tends to become a flush fluid (gas-liquid two-phase flow). There is a problem with abrasion and corrosion of the trim part. Also, since the flush fluid itself is discharged to the downstream side of the valve, it does not affect the controllability of the valve itself, but it is sensitive to stimulation from the lower field and becomes a swirling flow, or the natural vibration of the downstream piping system. If it matches with, a vibrating water hammer phenomenon may be continuously generated, and as a result, the downstream piping violently vibrates and an abnormal noise is generated.

FIG. 4 shows a conventional example of this type of single-seat type angle valve. 1 is a horizontal upstream pipe, and 2 is a vertical pipe below the downstream opening end of the upstream pipe 1. The downstream pipes 3 and 4 are an angle valve and a tail piece connected between the upstream pipe 1 and the downstream pipe 2. The angle valve 3 is fitted in a valve body 7 having a fluid inlet 5 which is orthogonal to each other and which is horizontally opened and a fluid outlet 6 which is vertically downwardly opened, and a fluid outlet 6 from below via a gasket 9. A seat ring 8, a valve shaft 12 that is vertically movably fitted in a valve shaft insertion hole 10 that opens in the upper surface of the valve body 7 via a seal member 11, and a holder 13 at the lower end of the valve shaft 12. A valve plug 15 that is attached and controls opening / closing of the fluid passage hole 14 of the seat ring 8, a guide bush 16 that is inserted into the valve shaft insertion hole 10 and slidably guides and holds the holder 13, and a valve shaft insertion hole. From the packing follower 17 that is inserted into the upper end opening of 10 to press the seal member 11, and the packing flange 19 that is fixed to the upper surface of the valve body 7 by a plurality of bolts 18 to press and fix the packing follower 17. Ri, the fluid inlet 5 is connected to the downstream side opening end of the upstream pipe 1, the tailpiece 4 to the fluid outlet port 6 is connected via a seat ring 8. The tail piece 4 holds the seat ring 8 in cooperation with the valve body 7 by being fixed to the lower surface of the valve body 7 by a plurality of bolts 20, and the upper end opening of the passage 21 formed through the center thereof. The portion is connected to the lower end opening of the seat ring 8 via the orifice 22, and the lower end is connected to the upper end opening of the downstream pipe 2. Therefore, as shown in FIG. 5, the controlled fluid 25 has a plug portion A and an orifice portion B.
The pressure is reduced by two steps at the valve plug 15
It reduces the decompression burden on the plug to extend the life of the plug. That is, on the downstream side of the valve, solid particles pass through the plug portion A at high speed, so that the outer peripheral surface of the characteristic portion of the valve plug 15 and the inner peripheral surface of the fluid flow hole 14 are abraded and worn. As a result, the flow path becomes larger than the originally designed value, so that the valve opening is lowered to maintain the pressure reducing performance. If the valve is worn out and the valve opening is reduced, the valve life will be extended. To date, a product having a long life has not been developed, and therefore, the orifice 22 is incorporated to form a two-stage depressurization structure to reduce the load on the valve plug 15. The orifice 22 is formed in a disc shape and has a flow hole 23 at the center. When designing such a fixed orifice 22, the pressure and flow rate values that are normally used are known from the plant operating conditions, and the plug-orifice burden reduction distribution is set. The orifice 22 is fixed in the seat ring 6 by an orifice retainer 24 fitted into the upper end opening of the tail piece 4.

[0004]

In the conventional angle valve described above, the controlled fluid 2 passing through the orifice 22 is used.
No. 5 has a property of recovering the pressure after being excessively decompressed, especially when operating at a high differential pressure, and therefore, as described above, a large amount of gas is generated in the over-decompression section to become a flush fluid. Further, since the orifice 22 has only one circulation hole 23, a swirling flow is generated when the controlled fluid 25 passes through, and as a result, a swirling flow is also generated on the downstream side of the orifice and strikes the inner wall of the pipe. As a result, there is a problem that the piping vibrates violently and an abnormal noise is generated. Further, since the generation of the swirling flow increases the resistance value of the pipe, the predicted Cv value (design value) may change in actual operation, which makes it impossible to perform accurate fluid control. Furthermore, when a swirling flow occurs in the slurry fluid, the slurry collects on the outer periphery of the flow and damages the pipe wall, and when cavitation occurs in the slurry fluid, the flow velocity increases, so the collision energy of the slurry also increases, and the pipe wall is further damaged. There was a problem such as the increase.

Therefore, the inventors of the present invention have variously changed the structure of the orifice in this respect, and as a result of various experiments,
By forming a plurality of circulation holes and forming the upstream opening of the circulation hole in a bosh-like shape, the fluid flow is stabilized, and it is possible to prevent the generation of swirling flow and cavitation in the downstream piping. I confirmed that I could do it.

Therefore, the present invention has been made on the basis of the above-mentioned conventional problems and experimental results. The object of the present invention is to stabilize the flow of fluid through an orifice and to prevent swirling flow and cavitation. It is an object of the present invention to provide a valve device capable of preventing the occurrence of the noise, improving the durability of the valve itself and the piping, and capable of quiet operation with less noise.

[0007]

In order to achieve the above object, the present invention has a valve plug for opening / closing a fluid passage hole of a seat ring arranged in a valve body, and a seat ring sandwiched with the valve body. In a valve device including a tail piece and an orifice arranged between the seat ring and the tail piece, a plurality of flow holes of the orifice are formed on substantially the same circumference around the center of the orifice, In addition, the opening on the upstream side of the through hole is formed in a morning glory shape with a roundness having a radius of 5 to 10 times the diameter of the through hole.

[0008]

In the present invention, the fluids passing through the flow passages of the orifice pass as a vortex flow, but they both restrain each other and move smoothly along the pipe wall, resulting in one large swirling flow. Never. The morning glory-shaped opening of the circulation hole moderates the degree of contraction of the fluid flowing into the circulation hole. Therefore, the flow velocity in the contracting portion is suppressed to be low, and the degree of cavitation is reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. 1A and 1B are a sectional view and a plan view of an orifice, and FIG. 2 is a sectional view of a trim portion of a valve device according to the present invention. In the figure, the same components as those of the conventional device shown in FIGS. 4 and 5 are designated by the same reference numerals, and the description thereof will be omitted. In these figures,
In this embodiment, a plurality of, for example, four circulation holes 23 are formed in the orifice 22, and the upstream side (seat ring side) opening of each circulation hole 23 has a radius r of 5 to 10 times the diameter of the circulation hole 23. It is formed into a morning glory type (trumpet type) with a rounded shape. The flow holes 23 are formed on a concentric circle near the outer periphery centered on the center of the orifice 22 and at intervals of about 90 °. Other configurations are similar to those of the conventional device.

In such a configuration, the orifice 22
The flow of the fluid passing through each of the circulation holes 23 becomes a vortex flow, and the jet flow coming out of the circulation hole 23 becomes a flow along the pipe wall because it is displaced from the center of the flow path. Therefore, the fluid flow is stable and does not become one large swirling flow.

FIG. 3 shows the upstream fluid pressure P1 (= 8 Kgf / c
It is a figure which shows the result of having measured the cavitation starting point (point where cavitation generate | occur | produces) of three types of orifices when m2) is made constant. In the figure, a curve I is a cavitation initiation point in a conventional orifice (type A) having one flow hole, and a curve II is a cavitation initiation in an orifice (type B) having one flow hole and a seat ring side opening formed in a morning glory shape. Points and curve III are cavitation initiation points in the orifice of the present invention (type C), the horizontal axis is the valve opening (%), and the vertical axis is the cavitation coefficient (σ). As is clear from this figure, in the type B orifice with one circulation hole and the upstream opening formed in the boshoku type, the cavitation coefficient σB is larger than the cavitation coefficient σA of the type A orifice with straight circulation holes. Can be made small (σB <σA). In other words, it is possible to enlarge the area where cavitation does not occur. This is because the roundness of the flow holes 23 affects the degree of contraction, and the degree of contraction is lessened in the type B, and therefore the flow velocity in the contracted portion is suppressed to be low, so that the occurrence of cavitation is less in the type B. This is because it is later than Type A. Further, in the case of the type C in which a plurality of circulation holes 23 are formed and the upstream side opening 23a is formed in a morning glory shape as in the present invention, the degree of contraction is low and the jet flow is subdivided. Due to the influence of the frictional force on the inner wall surface of the orifice, the maximum flow velocity is suppressed as compared with the type B, the jet length discharged from the orifice is short, and weak jets interfere with each other, resulting in a rapid mixing process. Therefore, it is considered that cavitation bubbles generated in a strong shear layer are difficult to be generated in type C. Therefore, type C
Has a smaller cavitation coefficient σ C than the type B cavitation coefficient σ B (σ C <σ B), and has a stable value with respect to the valve opening, so that the area where cavitation does not occur can be further expanded. Further, by forming a plurality of circulation holes 23, it is possible to simultaneously prevent the generation of the swirling flow as described above, so that an ideal valve device can be obtained.

Although the above embodiment has been described with respect to the case where four through holes 23 are provided, the present invention is not limited to this, and three, five, six, etc. may be appropriately increased or decreased. it can.

[0013]

As described above, in the valve device according to the present invention, a plurality of flow holes are formed in the orifice and the upstream side opening is opened in a bosh-like shape, so that the fluid flow is stable, The generation of swirling flow and cavitation can be reduced and prevented, and the durability and reliability of the valve device can be significantly improved. Further, if the swirling flow does not occur, it is possible to prevent the vibration and noise of the downstream side pipe, and it is possible to provide a quiet valve device.

[Brief description of drawings]

1A and 1B are a sectional view and a plan view of an orifice.

FIG. 2 is a sectional view of a trim portion showing an embodiment of the valve device according to the present invention.

FIG. 3 is a diagram showing a result of measuring cavitation initiation points of three kinds of orifices.

FIG. 4 is a sectional view showing a conventional example of a valve device.

FIG. 5 is a sectional view of a main part of the valve device.

[Explanation of symbols]

 1 Upstream Side Pipe 2 Downstream Side Pipe 3 Valve Device 4 Tailpiece 5 Fluid Inlet 6 Fluid Outlet 7 Valve Body 8 Seat Ring 14 Fluid Flow Hole 15 Valve Plug 22 Orifice 23 Flow Hole 23a Upstream Opening Portion

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mitsuo Kameyama 6-9-9 Komagome, Toshima-ku, Tokyo (72) Inventor Tatsushi Shinogaya 29-3 Takatsuto-cho, Midori-ku, Chiba-shi, Chiba (72) Inventor Koichi Okawa 4-1-1 Omagari, Samukawa-cho, Takaza-gun, Kanagawa Yamatake Honeywell Co., Ltd. Shonan Factory (72) Inventor Yoshiyuki Okatsu 4-1-1 Omagari, Samukawa-machi, Takaza-gun, Kanagawa Prefecture Shonan Factory, Yamatake

Claims (1)

[Claims] 1. A valve plug for controlling opening and closing of a fluid passage hole of a seat ring arranged in a valve body, a tail piece for sandwiching the seat ring together with the valve body, and a tail piece arranged between the seat ring and the tail piece. In a valve device having an orifice provided, a plurality of flow holes of the orifice are formed on substantially the same circumference with the center of the orifice as a center, and the upstream opening of the flow hole has a diameter of the flow hole of 5 A valve device characterized by being formed in a bosh shape with a radius of 10 times.