JP2954923B1 - Gate valve for cryogenic temperature - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To provide a gate valve for a cryogenic valve of a reduced valve seat type, in which a fluid remaining on a secondary side at the time of fully closing is suppressed to a minimum. SOLUTION: An inlet (2) is provided at one end of a valve box (1).
A flow path (A) is provided at the other end side so as to face the flow path (A). The flow path (A) has a lowermost portion (G) located in a straight line, and the flow-in port (2) and the flow-out port (3). ) So that the diameter is sequentially reduced toward the inside. The ring-shaped valve seats (4, 4) interposed in the middle of the flow path (A) have their lowermost parts (G1, G1) aligned with the lowermost part (G) of the flow path (A). The center line (L1) is located between the inlet (2) and the outlet (3) and the valve seat (4, 4) with respect to the center line (L2) between the inlet (2) and the outlet (3). ) Is set so as to be eccentric downward by a distance that is half the difference between the inner diameter and the inner diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic gate valve, and more particularly to a cryogenic gate valve having a reduced valve seat inner diameter than a pipe inner diameter.

Conventionally, as a cryogenic gate valve, as shown in FIG. 3, an inner diameter of a flow path A which linearly connects an inlet 2 and an outlet 3 of a valve box 1, and a valve seat 4, Those having the same inner diameter as 4 are widely used. That is, in the illustrated conventional example, ring-shaped valve seats 4 and 4 facing each other are provided at predetermined intervals in the flow path A of the valve box 1. The valve seats 4 and 4 are formed in a ring shape coaxial with the flow path A, and are opposed to each other in a substantially V-shape in front so as to narrow a lower space, and are respectively welded to the valve box 1 to ensure high airtightness. Be stopped. Above both valve seats 4, 4, a valve upper chamber B for raising and lowering the valve is provided.

The lower and upper valve seats 6, which pass through the valve upper chamber B and enter between the valve seats 4, 4, are attached to the lower ends of the valve seats 4, 4, respectively.
A valve element 5 inserted between the elements 4 is attached. In addition,
Since the valve element 5 is distorted at extremely low temperatures in the valve box 1 and the like,
It has a flexible structure.

That is, the valve element 5 is formed in a disk shape having a wedge-shaped cross section in consideration of low-temperature distortion, and is provided with a kerf C having a predetermined depth all around the circumference thereof, thereby providing a flexible structure. Even if there is a low-temperature distortion in the valve box 1 or the like, the valve element 5 deforms to follow the distortion and the entire surface of the two valve seats 4 and 4 (actually, the secondary valve seat 4 on the right side in FIG. (It keeps hermetic.)

[0005] When the fluid in the upper chamber B of the valve is vaporized while the valve element 5 is closed, the pressure in the upper chamber B may be abnormally increased. B has a through hole D communicating with the primary side of the valve element 5.

In FIG. 3, E is a valve storage chamber, 7 is a lid,
8 is a gasket, 9 is a cooling plate, 10 is packing, 11 is a grease injector, 13 is a steering wheel,
These are conventionally known ones.

[0007] This type of gate valve is provided with a flow path A in the valve box 1.
Is linear, the pressure loss when the valve element 5 is fully opened is small, and even if the valve seat inner diameter is reduced to about 80% of the pipe diameter (of the inlet 2 and the outlet 3), the effect on the cryogenic plant is reduced. Has been proven to be rare. Since reduction in cost can be achieved by reducing the size of the valve seat, there has been a demand for the use of a valve seat reduced type for this kind of cryogenic gate valve.

Conventionally, as shown in FIG. 2, an ordinary valve seat reduction type gate valve has been proposed. This valve seat reduction type gate valve is provided with an inlet 2 at one end of a valve box 1 and an outlet 3 at the other end, and the inlet 2 and the outlet 3 are sequentially reduced inward. A ring-shaped valve seat 4, which is linearly communicated with a flow path A having a diameter and is concentric with the flow path A and smaller in inner diameter than the inflow port 2 and the outflow port 3 in the middle of the flow path A. 4 are provided facing each other at a predetermined interval.

However, the above concentric valve seat reducing type gate valve is
When used for cryogenic use of LNG or the like, this kind of cryogenic gate valve requires a packing 10 for sealing the elevating valve shaft 6 at room temperature, and is usually provided with a valve box as shown in FIG. The valve shaft is mounted vertically with one side facing the ground (downward) and the packing 10 side facing the top (upper). Therefore, when using this kind of cryogenic gate valve, when closing the valve, the secondary side (downstream side, right side in the figure)
When the valve is fully closed, the valve seat 4 forms a weir, and the fluid corresponding to the range S shown in FIG. 2 will remain.

[0010] The fluid remaining on the secondary side as described above is
If the cryogenic fluid is vaporized, the pressure may rise due to vaporization. Therefore, this stagnant fluid must be discharged as a drain from the drain valve B1 or the like from the piping, and as a result, a large amount of expensive cryogenic fluid is discharged. There was a problem that it would be discarded.

[0011]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above problems, and has a valve seat reduced type cryogenic gate valve in which the fluid remaining on the secondary side is minimized when fully closed. It is an object to provide

[0012]

In order to achieve the above object, the present invention provides an inflow port 2 at one end of a valve box 1 and an outflow port 3 at the other end thereof. And the outlet 3 are connected by a linear flow path A, and ring-shaped valve seats 4 and 4 are interposed at predetermined intervals in the flow path A so as to face each other. In the cryogenic gate valve provided with the valve body 5 that moves up and down between the 4, 4 and 4, the lower end G of the flow path A is located on a straight line, and the flow path A is inwardly from the inflow port 2 and the outflow port 3. The two ring-shaped valve seats 4 and 4 interposed in the middle of the flow path A have lowermost parts G1 and G1 that are the lowermost parts G of the flowpath A. And the inner diameter is determined to be an inner diameter adapted to the reduced diameter portion of the flow path A, and the center line L1 of the valve seats 4 and 4 is set with respect to the center line L2 of the inflow port 2 and the outflow port 3. Flow In which it took technical means, characterized in that the set to be eccentric to one half of the distance below the difference between the inner diameter of the mouth 2 and the outlet 3 and the valve seat 4, 4.

Therefore, the cryogenic gate valve of the present invention has an effect of reducing the inner diameters of the valve seats 4 and 4 with respect to the pipe diameter corresponding to the diameter of the inflow port 2 and the outflow port 3.

Even if the inner diameter of the valve seat is reduced as described above, the gate valve for cryogenic use of the present invention has the lowest part of the flow path A communicating between the inflow port 2 and the outflow port 3 positioned in a straight line. Therefore, when the valve element 5 is moved down to the fully closed state, no dam is formed by the valve seat 4 between the valve and the downstream side.

[0015]

Next, an embodiment of the present invention will be described with reference to the accompanying drawings. In the figure, reference numeral 1 denotes a valve box, an inlet 2 is provided at one end of the valve box 1 and an outlet 3 is provided at the other end thereof, and a straight line is formed between the inlet 2 and the outlet 3. Channel A
The ring-shaped valve seats 4 and 4 are interposed at predetermined intervals in the flow path A so as to face each other, and a valve body 5 that moves up and down between the valve seats 4 and 4 is provided. Is the same as before.

In the valve box 1, the inlet 2 and the outlet 3 have the same diameter, and the inner diameter is interposed in the same pipe as the inlet 2 and the outlet 3. It is the same as before.

In order to interpose the ring-shaped valve seats 4 and 4 in the middle of the flow path A, a valve storage chamber E is provided in the middle of the flow path A. It is the same as the conventional one that is stored and fixed in the valve storage chamber E.

According to the present invention, in the gate valve for cryogenic use as described above, the flow path A has a lowermost portion G located in a straight line, and is sequentially inward from the inlet 2 and the outlet 3. It is configured to reduce the diameter.

That is, the flow path A is conventionally formed in a straight cylindrical shape as shown in FIG. 3 or is gradually reduced inward with a straight line as a center line as shown in FIG. Was something. In contrast to such a conventional example, the flow path A of the present invention is reduced in diameter toward the inside and decentered, so that the top end of the flow path A is successively lowered toward the inside. The lowermost part G is located on a straight line.

The channel A has the same diameter reduction ratio and the same eccentricity on the primary side as the inflow port 2 side and on the secondary side as the outflow port 3 side.

The lowermost portions of the valve seats 4 and 4 interposed in the flow path A coincide with the lowermost portions of the flow path A, and the inner diameter of the valve seats 4 matches the reduced diameter portion of the flow path A. The inside diameter is made.

The middle of the flow path A is a precise center portion of the flow path A, and the flow path A is opened so as to face the valve seat chamber E which communicates the center side with the valve upper chamber B. There is something. The opening of the flow path A facing the valve seat chamber E has the same inner diameter and is accurately opposed to have a common center axis.

If the inner diameters of the two valve seats 4 and 4 are different or the eccentric positions are different, the valve element 5 and the valve seats 4 and 4 are completely pressed against each other when used for a cryogenic gate valve. Without this, the airtightness may be impaired. Therefore, the valve seats 4, 4 have their lowermost portions G1, G1 coincident with the lowermost portion G of the flow path A, and have an inner diameter adapted to the reduced diameter portion of the flow path A, that is, the flow path A Has the same inner diameter as the opening opening to the valve seat chamber E.

Conventionally, the valve seats 4 and 4 are welded to the periphery of the opening of the valve storage chamber E of the flow passage A so as to be opposed to a straight ring shape whose inner diameter does not change. In the same manner as in the prior art, the gap between the valve seats 4 and 4 is such that the upper portion is wide and the lower portion is gradually narrowed.

According to the present invention, the center line L1 of the valve seats 4 and 4 is aligned with the center line L2 of the inlet 2 and the outlet 3 and the inlets 2 and the outlet 3 and the valve seats 4 and 4. It is set so as to be eccentric downward by half the distance of the difference between the inner diameters.

That is, according to the present invention, as described above, since the diameter of the flow path A is reduced inward and the lowermost part thereof is located on a straight line, the center line L1 of the valve seats 4, 4 is formed.
Is eccentric below a center line L2 between the inflow port 2 and the outflow port 3 by a distance which is half the difference between the inner diameters of the inflow port 2 and the outflow port 3 and the valve seats 4 and 4. .

A flexible valve element inserted between the two valve seats 4 and 4 is provided at the lower end of an elevating valve rod 6 which enters between the two valve seats 4 and 4 through the valve upper chamber B. The valve body 5 is formed in a disk shape of a wedge-shaped cross section in consideration of low-temperature distortion, and a kerf C of a predetermined depth is provided along the entire circumference thereof as in the conventional case. And the valve element 5
Is provided with a through hole D through which the valve upper chamber B communicates with the primary side of the valve body 5 as in the prior art.

[0028]

Since the present invention is as described above, even if the valve is of a reduction valve seat type, the flow path G at the lower part of the valve box is linearly communicated with the lower part of the inner diameter of the pipe, so that extremely low temperature can be achieved. The liquefied gas does not stay in the pipe, and therefore a low-cost gate valve for cryogenic use that does not cause abnormal pressure rise can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a cryogenic gate valve of the present invention.

FIG. 2 is a longitudinal sectional view of a conventional valve seat reduced concentric type cryogenic gate valve.

FIG. 3 is a longitudinal sectional view of another conventional cryogenic gate valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve box 2 Inlet 3 Outlet 4 Valve seat 5 Valve body A Flow path G Lowest end L1 Center line L2 Center line

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Katsuhiko Maruyama 3-2-2 Hisamoto, Takatsu-ku, Kawasaki-shi, Kanagawa Prefecture Hirata Valve Industry Co., Ltd. Headquarters contact office (56) References JP-A-9-1112713 (JP, A) Hikaru Hira 1-146078 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F16K 3/00-3/36

Claims (1)

(57) [Claims] 1. An inlet (2) is provided at one end of a valve box (1).
An outflow port (3) is provided on the other end side so as to oppose, and the inflow port (2) and the outflow port (3) are connected by a linear flow path (A). A ring-shaped valve seat (4,
In a cryogenic gate valve provided with a valve element (5) which is interposed between the valve seats (4) at predetermined intervals and provided between the valve seats (4, 4), the flow path (A) Is configured such that its lowermost part (G) is located on a straight line and is gradually reduced in diameter from the inflow port (2) and the outflow port (3) inward. ), The lower ends (G1, G1) of the ring-shaped valve seats (4, 4) are aligned with the lowermost part (G) of the flow path (A), and the inner diameter of the valve seat is The center diameter (L1) of the valve seat (4, 4) is adjusted to the inflow port (2).
With respect to the center line (L2) between the valve (4) and the outlet (3) with respect to the center line (L2) of the valve (4). A cryogenic gate valve characterized in that it is set to: