JP2001295952A - Fine safety valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine safety valve prevented from the intrusion of gas (intake air) from the outside and hardly influenced by downstream pressure. SOLUTION: This safety valve provided with a bellows 68 mounted to a steam boiler, a hot water boiler or a pressure vessel is formed in airtight welded joint structure to prevent the intrusion of gas from the outside through a valve element 64 on both the upstream side and downstream side of the valve at a stop or under the condition that the downstream pressure fluctuates from the atmospheric pressure to the vacuum pressure, and the downstream side is connected to a closed part of the vessel 98 or the like by welding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-precision safety valve used for a safety device in which the secondary side (outlet side) of a safety valve is connected to a sealed portion such as a container that varies from atmospheric pressure to vacuum pressure. It is.

[0002]

2. Description of the Related Art A safety valve is attached to a steam boiler, a hot water boiler, other pressure vessels, and the like. However, in a conventional safety valve, the secondary side is usually opened to the atmosphere.
It was designed and manufactured with no pressure change on the outlet side. However, when dealing with restrictions on operating conditions, built-in objects, objects that are difficult to blow out to the outside, etc., they cannot be released to the outside. If such operating conditions are considered, the conventional safety valve cannot cope. In particular, under operating conditions in which the secondary side changes from atmospheric pressure to vacuum, the set pressure may fluctuate depending on the operating conditions, and it has been difficult to maintain stable operation.

FIG. 7 shows an example of a conventional full displacement type safety valve. 10 is a valve body, 12 is a seat (valve seat), 14 is a blowdown ring, 16 is a gasket, 18 is a ring fixing bolt, 20 is a lock nut, 22 is an upper ring, 24 is a valve guide, 26 is a valve, and 28 is a valve. Bellows, 30 and 32 are gaskets, 34 is a valve stem guide, 36
Is a spring, 38 is a valve stem, 40 is a protective cylinder, 42 is a cap,
44 is an adjusting screw, 46 is an inlet, and 48 is an outlet.
The outlet 48 is in contact with the atmosphere, and when the set pressure is reached,
The valve 26 rises against the spring force, and the fluid flowing from the inlet 46 is discharged to the atmosphere from the outlet 48.

[0004]

In the conventional safety valve as shown in FIG. 7, as described above, in an operating condition in which the secondary side changes from atmospheric pressure to vacuum, the set pressure fluctuates depending on the operating condition. There is a danger that stable operation cannot be continued. Further, since the seal is made by using a gasket, there is a problem that the sealing property is not particularly good for a high temperature fluid.

[0005] The present invention has been made in view of the above points,
An object of the present invention is to use a gasket (including a packing) or rubber without using a gas (externally) even under conditions in which the secondary pressure fluctuates in a range from the atmospheric pressure to the vacuum pressure without using a gasket (including packing) or rubber. It is an object of the present invention to provide a high-precision safety valve that prevents inflow of the intake air, and is hardly affected by the pressure on the secondary side. Another object of the present invention is to provide a structure in which the bellows and the valve body are sealed by welding so that the set pressure of the primary pressure does not fluctuate due to the fluctuation of the secondary pressure, and the pressure difference between the secondary pressure and the atmospheric pressure. Another object of the present invention is to provide a high-precision safety valve having a structure that is unlikely to cause malfunction due to the above, and a welded seal structure in which the secondary side is not exposed to the atmosphere. Further, an object of the present invention is to perform welding in order to improve the sealing property of the adjusting ring fixing bolt portion, and to provide a space in which heat is hardly transmitted to the fixing bolt in order to make it less susceptible to heat during welding. To provide a high-precision safety valve having a welded seal structure.

[0006]

In order to achieve the above object, a high-precision safety valve of the present invention is a safety valve having a bellows attached to a steam boiler, a hot water boiler, a pressure vessel, etc. Under a condition where the pressure fluctuates from the atmospheric pressure to the vacuum pressure or when the valve is stopped, both the primary and secondary sides of the valve have a hermetic welded joint structure to prevent gas (intake) from entering from outside through the valve body. The side is welded and connected to a sealed portion such as a container (see FIG. 1).

The high-precision safety valve of the present invention is a safety valve having a bellows attached to a steam boiler, a hot water boiler, a pressure vessel, or the like, wherein the secondary pressure is a vacuum pressure and the primary pressure is large. Even if the pressure is higher than the atmospheric pressure, the primary and secondary sides of the valve are hermetically welded and joined so that gas does not enter from outside through the valve body, and the secondary side is welded to a closed part such as a container. (Fig. 1
reference).

[0008] In these high-precision safety valves, the joint between the valve body and the bellows in the safety valve has an airtight welded structure in order to improve the sealing performance against the high temperature fluid to the outside air so that the safety valve is not affected by thermal strain. Preferably, a heat radiating portion is provided between the valve body and the welded portion (see FIGS. 1 to 3). In addition, an adjustment ring is provided to improve the accuracy of the blowing pressure, pre-leakage pressure, and blow-off pressure.The sealing between the thread of the fixing bolt for preventing the adjustment ring from rotating and the outside air is improved. In order to make it difficult to transmit the heat distortion of
Preferably, a space for heat insulation is provided in the fixing bolt, and one end of the fixing bolt and the valve body are hermetically welded (see FIGS. 1 and 4).

It is preferable that the heat radiating portion between the valve body and the welded portion be a heat radiating fin (see FIG. 2) or that the heat radiating portion be a thin and thick portion (see FIG. 3). ). As the bellows, a welded bellows that is flexible and has excellent pressure resistance and durability is used.

As described above, the high-precision safety valve of the present invention has a welded structure without using a gasket or rubber in order to improve the sealing performance against a high-temperature fluid to the outside air. However, in the safety valve of the conventional structure, instability of operation due to thermal distortion during welding and leakage of valve seats were generally raised as concerns, but in the safety valve of the present invention, welding distortion gives anxiety to performance. There is no structure. As an example, for the welding of the valve body and the bellows: (1) The distance between the welded part and the valve body is increased. (2) Radiation fins are provided in a part between the weld and the valve body,
The heat at the time of welding is radiated by the fins, so that the effect of the heat is hardly transmitted to the valve body. (3) Part of the steel material between the welded portion and the valve body is made thinner to reduce the heat transmission area, thereby making it difficult to transmit the effect of heat to the valve body. The structure is adopted so that heat is not easily transmitted to the valve body and thermal strain is not applied.

In order to exhibit high accuracy, the bellows used must be soft and have excellent pressure resistance and durability. Therefore, a welded bellows is used instead of a conventional formed bellows. In addition, when using an adjustment ring that is indispensable to improve the accuracy of the blowout pressure, pre-leakage pressure, and blowoff pressure, a detent locking bolt is required. Welding is used as a method to improve the sealing performance. As a method of making it difficult to transmit the heat distortion at the time of welding, welding is not performed directly on the fixing bolt, but a space is provided to make heat transfer difficult.

When the primary pressure rises, the valve element is pushed up to release the pressure to the secondary side in the normal operation of the safety valve. In the conventional safety valve, the spring portion which pushes down the valve element also has the valve element. The secondary side is also exposed to the outside air and is normally under atmospheric pressure. However, when the secondary side is connected to a container that fluctuates in pressure, it is necessary to seal by welding so as not to be affected by the atmospheric pressure. The present invention employs such a configuration. In this case, the atmospheric pressure is applied only to the outside air side of the valve body. In this case, the valve element operates at the difference between the primary pressure and the atmospheric pressure,
No pressure fluctuation on the secondary side. Therefore, even if the pressure on the secondary side fluctuates and the differential pressure between the primary pressure and the secondary pressure fluctuates, there is a characteristic that the operating point at which the pressure is set does not change or malfunctions. Since the valve element operates based on the pressure difference between the primary side and the atmospheric pressure on the outside air side, the operating point operated by increasing the primary side pressure is stable and is not affected by the pressure fluctuation on the secondary side. Will be.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments and can be implemented with appropriate modifications. FIG. 1 shows a high-precision safety valve according to a first embodiment of the present invention, FIG. 2 shows an example around a welded portion between a bellows and a valve (valve element) in FIG. 1, and FIG.
2 shows the area around the fixing bolt (ring fixing bolt). 50 is a valve body, 52 is a seat (valve seat), 54
Is a protective cylinder, 56 is a cap, 58 is a blowdown ring, 60 is a valve guide, 62 is an upper ring, 64
Is a valve (valve element), 66 is a spindle, 68 is a bellows, 70 is a guide, 72 is a lift limiting plate, 74 is a spring bearing, 76 is an adjusting screw, 78 is a lock nut, 80 is a ring fixing bolt, 82 is a spring, 84 is a hexagon nut, 86 is a stud, 88 is an inlet, and 90 is an outlet.

The safety valve has a structure in which a protection cylinder 54 is connected to an upper part of a valve body 50 having a seat (valve seat) 52 and a cap 56 is connected to the upper part of the protection cylinder 54.
A valve (valve element) 64 that is opened and closed with the seat 52 is provided, a spindle 66 is connected to the valve 64, and a spring 82 is disposed around the spindle 66.
A bellows 68 is provided for airtightly connecting the space 92 on the upper side with the space 94 in the protection cylinder 54. When the pressure of the inlet 88 is smaller than the set pressure, the valve 64 is attached to the seat 52 by the force of the spring 82. The contact portion is closed and the entrance portion 88 is closed.
Is higher than the set pressure, the valve 64 rises against the force of the spring 82 and is opened.

In the safety valve thus configured, the inlet portion 88 is hermetically welded to the primary container 96 and the outlet portion 90 is hermetically welded to the secondary container 98. Therefore, the outlet 90 is under pressure in the secondary container 98. Atmospheric pressure is applied to a space 92 above the valve 64 and a space 94 in the protection cylinder 54.
As described above, under the condition where the secondary pressure fluctuates from the atmospheric pressure to the vacuum pressure or at the time of stop, gas (intake) enters from the outside through the valve (valve element) 64 on both the primary side and the secondary side of the valve. In order to prevent this, an airtight welded joint structure is adopted.

In the safety valve according to the present embodiment, no gasket or rubber is used, and all portions where a gasket or the like is conventionally used have an airtight welded joint structure.
In addition, both the primary and secondary sides of the valve prevent intake air from entering from outside through the valve body so that stable operation can be performed even if the primary side pressure is higher than atmospheric pressure and the secondary side pressure is vacuum. It has an airtight welded joint structure. In particular, in order to enhance the sealing performance of the safety valve against outside air with respect to a high-temperature fluid, the valve (valve element) 64 and the bellows 68 of the safety valve are hermetically welded so that the valve 64 is not affected by thermal distortion. A heat dissipating part is provided between the welding part.

FIG. 2 shows an example of the heat radiating section. That is, the heat radiating portion 100 is configured as the fin structure portion 102 so as to radiate heat during welding. 104 is a welded part, 106 is a bellows fixing member. FIG. 3 shows another example of the heat radiation unit 100a. This heat radiation part 100a
Is made of a thin material so as to reduce the amount of heat transmitted during welding as the thin thick portion 108. As the bellows 68, a flexible welding bellows having excellent pressure resistance and durability is used.

Adjustment rings such as a blow-down ring 58 and an upper ring 62 are provided to increase the accuracy of the blow-out pressure, the pre-leakage pressure, and the blow-off pressure. Fixing bolts for preventing the rotation of these adjustment rings are provided. That is, in order to enhance the sealing performance between the thread portion of the ring stopper bolt 80 and the outside air and to reduce the heat distortion during welding, a space 110 is provided in the ring stopper bolt 80 to make it difficult to transmit heat. One end of the fixing bolt 80 and the valve body 50 are hermetically welded. Reference numeral 112 denotes a weld.

In the high-precision safety valve configured as described above, for example, a full-volume type safety valve, when the pressure on the safety valve inlet side increases and approaches the blowout pressure, the fluid that tries to push up the valve (valve element) 64 is supplied to the valve 64. Approaching the force of the spring 82 pushing down the pressure, and a pre-leakage occurs from a pressure about 3% lower than the blowing pressure. Due to this pre-leakage, the pressure in the seal side surface portion of the valve 64 is accumulated, and when the specified blowing pressure is reached, the popping operation is performed vigorously. FIG. 5 shows a state when the valve is closed, and FIG. 6 shows a state when the valve is opened.
When the fluid is discharged to the outlet side by the hopping operation of the valve 64, the pressure on the inlet side of the safety valve decreases, so that the lift pressure decreases, and the repulsive force of the spring 82 wins, and the valve closes.

[0020]

As described above, the present invention has the following effects. (1) The safety valve of the present invention is less likely to be affected by the pressure on the outlet side of the safety valve, and is suitable for use as a safety valve to be attached to a system that requires high-precision operating characteristics. In addition, the selection of the bellows and the adoption of a welding structure that does not easily cause thermal strain as compared with the prior art can provide a relatively inexpensive and highly accurate safety valve. (2) Due to the structure of the safety valve of the present invention, the effect of the safety valve that releases the pressure without abnormally increasing the primary pressure, and a sealed portion such as another container connected to the secondary without releasing the primary pressure to the atmosphere. As a device including the primary side and the secondary side,
This has the effect of maintaining sealing properties. This makes it possible to release the pressure of contents that are not desirable to be released to the atmosphere by not only steam but also flammable gas, toxic gas and the like, which is practical for a wide range of applications, and the effect is extremely large.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view of a high-precision safety valve according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing details of an example around a welded joint between a bellows and a valve (valve element) in FIG. 1;

FIG. 3 is an enlarged sectional view showing details of another example around a welded joint between a bellows and a valve (valve element) in FIG. 1;

FIG. 4 is an enlarged view showing the vicinity of a fixing bolt in FIG. 1;

FIG. 5 is a longitudinal sectional view showing a state in which the safety valve shown in FIG. 1 is closed.

FIG. 6 is a longitudinal sectional view showing a state in which the safety valve shown in FIG. 1 is opened.

FIG. 7 is an explanatory longitudinal sectional view showing an example of a conventional safety valve.

[Explanation of symbols]

 Reference Signs List 50 valve body 52 seat (valve seat) 54 protective cylinder 56 cap 58 blowdown ring 60 valve guide 62 upper ring 64 valve (valve element) 66 spindle 68 bellows 70 guide 72 lift limiting plate 74 spring receiver 76 adjusting screw 78 lock nut 80 Ring stop bolt 82 Spring 84 Hex nut 86 Stud bolt 88 Inlet part 90 Outlet part 92, 94 Space 96 Primary container 98 Secondary container 100, 100a Heat radiating part 102 Fin structure part 104 Welding part 106 Bellows fixing member 108 Thin thickness Part 110 Space 112 Weld

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kenichi Saito 1000 Aochi-cho, Kusatsu-shi, Shiga Kawagei Kogyo Kogyo Co., Ltd. (72) Inventor Masumi Ota 1000 Aochi-cho, Kusatsu-shi, Shiga Prefecture Kawagei-Hiroshi Kogyo Co., Ltd. Miyamae 955 Yoshitake Co., Ltd. Komaki Plant (72) Inventor Hideaki Kajiyama Komaki City, Aichi Prefecture Oirika De Nitta character Miyamae 955 Yoshitake Co., Ltd. Komaki Plant F term (reference) 3H059 AA05 BB29 BB40 CC01 CD05 CF14 EE01 FF06 FF07 FF17 3H066 AA01 BA19 BA37 BA38

Claims (7)

[Claims] 1. A safety valve provided with a bellows attached to a steam boiler, a hot water boiler, a pressure vessel, etc., wherein the primary side of the valve is operated under conditions where the secondary pressure fluctuates from atmospheric pressure to vacuum pressure or when the valve is stopped. A high-precision safety valve having an air-tight welded joint structure so that gas does not enter from the outside through a valve body on both the secondary side and a secondary side welded to a closed portion such as a container. 2. A safety valve having a bellows attached to a steam boiler, a hot water boiler, a pressure vessel, or the like, wherein the secondary pressure is a vacuum pressure and the primary pressure is a pressure higher than the atmospheric pressure. A high-precision safety valve characterized in that both the primary and secondary sides of the valve have an airtight welded joint structure so that gas does not enter from outside through the valve body, and the secondary side is welded and connected to a closed part such as a container. . 3. The valve body and the bellows in the safety valve have a hermetically welded structure for improving the sealing performance of the high temperature fluid to the outside air, and are welded to the valve body so as not to be affected by thermal strain. The high-precision safety valve according to claim 1 or 2, wherein a heat radiating part is provided between the safety part and the part. 4. An adjusting ring is provided to increase the accuracy of the blowing pressure, the pre-leakage pressure, and the blow-off pressure, and a sealing portion between a screw portion of a fixing bolt for preventing the adjusting ring from rotating and external air is improved. Further, a heat insulating space is provided in the fixing bolt and one end of the fixing bolt and the valve body are hermetically welded so that heat distortion during welding is hardly transmitted.
2. The high-precision safety valve according to 2 or 3. 5. The high-precision safety valve according to claim 3, wherein the radiator is a radiator fin. 6. The high-precision safety valve according to claim 3, wherein the heat radiating portion is a thin and thick portion. 7. The high-precision safety valve according to claim 1, wherein the bellows is a flexible bellows having excellent pressure resistance and durability.