JP3556565B2 - High precision safety valve - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-precision safety valve used for a safety device in which a secondary side (outlet side) of a safety valve is connected to a closed portion such as a container that fluctuates from atmospheric pressure to vacuum pressure.
[0002]
[Prior art]
A safety valve is attached to a steam boiler, hot water boiler, or other pressure vessel.However, in a conventional safety valve, since the secondary side is usually opened to the atmosphere, it is designed that there is no pressure change on the outlet side. Had been produced. However, when dealing with restrictions on operating conditions, built-in objects, and objects that are difficult to blow out to the outside, 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.
[0003]
FIG. 7 shows an example of a conventional full-volume safety valve. 10 is a valve body, 12 is a seat (valve seat), 14 is a blow down 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, 28 is a valve. Bellows 30, 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 portion 48 is in contact with the atmosphere, and when the pressure reaches the set pressure, the valve 26 rises against the spring force, and the fluid flowing from the inlet portion 46 is discharged from the outlet portion 48 to the atmosphere.
[0004]
[Problems to be solved by the invention]
In the conventional safety valve as shown in FIG. 7, as described above, under the operating condition where the secondary side changes from the atmospheric pressure to the vacuum, the set pressure may fluctuate depending on the operating condition. I can't continue. In addition, 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, and an object of the present invention is to use a gasket (including a packing) and rubbers, all of which are welded structures, and the secondary pressure is from atmospheric pressure to vacuum pressure. The purpose of the present invention is to provide a high-precision safety valve that prevents gas (intake) from entering from outside even under conditions that fluctuate in the range, and that is not easily affected by 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. It is an object of the present invention 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 to improve the sealing property of the adjusting ring fixing bolt portion, and to provide a space for preventing heat from being transmitted to the fixing bolt in order to reduce the influence of heat during welding. And a high-precision safety valve having a welded seal structure.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a high-precision safety valve of the present invention is a safety valve including a bellows 68 attached to a steam boiler, a hot water boiler, a pressure vessel, or the like, and has a secondary side pressure from atmospheric pressure to vacuum pressure. when conditions or stop varying, as a gas from the outside (intake) does not enter through the valve body 64 in both the primary and secondary sides of the valve, a gas-tight weld joint structure, the sealing portion of such container secondary side In order to enhance the sealing performance of the safety valve to the outside air with respect to the high-temperature fluid, a flexible, pressure-resistant and durable welding bellows is used as the bellows 68, and the valve body 64 and the welding bellows of the safety valve are connected. And a welded structure via a bellows fixing member 106, and a radiating portion 100 as a radiating fin is provided between the valve body 64 and the welded portion 104 so as not to be affected by thermal strain. In order to improve the accuracy of the blowout pressure, pre-leakage pressure, and blowoff pressure, an adjustment ring is provided to improve the sealing performance between the thread of the fixing bolt for preventing the adjustment ring from rotating and the outside air, and for welding. In order to make it difficult to transmit the thermal strain, a space 110 for heat insulation is provided in the fixing bolt, and one end of the fixing bolt and the valve body 50 are hermetically welded (FIGS. 1 and 2). , FIG. 4 ).
[0007]
Also, highly accurate safety valve of the present invention is a safety valve provided with a bellows 68 attached to the steam boiler, a secondary pressure is a vacuum pressure, even pressure the primary pressure is higher than the atmospheric pressure In order to prevent gas from entering from outside through the valve body 64 on both the primary side and the secondary side of the valve, the safety valve has an airtight welded joint structure, and the secondary side is welded and connected to the sealed portion of the vacuum vessel. In order to enhance the sealing performance against the outside air, a flexible, pressure-resistant, and durable welding bellows is used as the bellows 68, and the connection between the valve body 64 and the welding bellows in the safety valve is airtight through the bellows fixing member 106. A heat radiating portion 100 is provided between the valve body 64 and the welded portion 104 so as not to be affected by thermal strain. To increase the degree of adjustment, an adjustment ring is provided.To increase the sealing performance between the screw part of the fixing bolt for preventing rotation of this adjustment ring and the outside air, and to make it difficult to transmit heat distortion during welding, the fixing bolt A space 110 for heat insulation is provided in the inside, and one end of the fixing bolt and the valve body 50 are hermetically welded (see FIGS. 1, 2, and 4).
[0008]
The high-precision safety valve of the present invention is a safety valve including a bellows 68 attached to a steam boiler, a hot water boiler, a pressure vessel, or the like. In order to prevent gas from entering from the outside through the valve body 64 on both the primary and secondary sides of the valve, the safety valve has an airtight welded joint structure, and the secondary side is welded and connected to a sealed portion such as a container. In order to enhance the sealing performance against the outside air, a flexible, pressure-resistant, and durable welding bellows is used as the bellows 68, and the connection between the valve body 64 and the welding bellows in the safety valve is airtight through the bellows fixing member 106. And a heat dissipating portion 100a, which is a thin-walled portion 108, is provided between the valve body 64 and the welded portion 104 so as not to be affected by thermal strain. An adjusting ring is provided to increase the accuracy of force and blow-off pressure.The sealing of the screw of the fixing bolt for preventing rotation of this adjusting ring from the outside air is improved, and heat distortion during welding is hardly transmitted. To this end, a space 110 for heat insulation is provided in the fixing bolt, and one end of the fixing bolt and the valve body 50 are hermetically welded (see FIGS. 1, 3, and 4). .
[0009]
Also, highly accurate safety valve of the present invention is a safety valve provided with a bellows 68 attached to the steam boiler, a secondary pressure is a vacuum pressure, even pressure the primary pressure is higher than the atmospheric pressure In order to prevent gas from entering from outside through the valve body 64 on both the primary side and the secondary side of the valve, the safety valve has an airtight welded joint structure, and the secondary side is welded and connected to the sealed portion of the vacuum vessel. In order to enhance the sealing performance against the outside air, a flexible, pressure-resistant, and durable welding bellows is used as the bellows 68, and the connection between the valve body 64 and the welding bellows in the safety valve is airtight through the bellows fixing member 106. And a heat dissipating portion 100a, which is a thin-walled portion 108, is provided between the valve body 64 and the welded portion 104 so as not to be affected by thermal distortion. An adjustment ring is provided to increase the accuracy of the force, and it is fixed to improve the sealing performance between the screw part of the fixing bolt to prevent rotation of this adjustment ring and the outside air, and to make it difficult to transmit heat distortion during welding. A heat insulating space 110 is provided in the bolt, and one end of the fixing bolt and the valve body 50 are hermetically welded (see FIGS. 1, 3, and 4).
[0010]
As described above, in the high-precision safety valve of the present invention, in particular, a gasket or rubber is not used in order to enhance the sealing performance against a high-temperature fluid to the outside air, and the safety valve is entirely welded. However, in the safety valve of the conventional structure, instability of operation due to thermal strain during welding and valve seat leakage 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 welding the valve body and bellows,
(1) Leave a distance between the weld and the valve.
(2) A radiating fin is provided in a part between the welded portion and the valve body, and the heat at the time of welding is radiated by the fin, thereby making it difficult to transmit the influence of the heat 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.
[0011]
In order to exhibit high precision, the bellows used must be soft and have excellent pressure resistance and durability, so that a welded bellows is used instead of the conventional molded 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 rotation stop fixing bolt is required. Welding is a technique for improving the sealing performance of steel. As a method of making it difficult to transmit the thermal strain during welding, welding is not performed directly on the fixing bolt, but a space is provided to make the heat difficult to transmit.
[0012]
When the primary pressure rises, the valve element is pushed up to release the pressure to the secondary side, which is the operation of a normal safety valve.In a conventional safety valve, the spring that presses down the valve element also has a secondary function of the valve element. The side is also exposed to the outside air and is normally at 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 atmospheric pressure, and 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, and does not receive the secondary pressure fluctuation. 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]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. However, 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. The area around the bolt (ring fixing bolt) is shown. 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 bolt, 88 Denotes an inlet, and 90 denotes an outlet.
[0014]
The safety valve includes a valve body 50 having a seat (valve seat) 52, a protection cylinder 54 connected to an upper part of the valve body 50, and a cap 56 connected to the upper part of the protection cylinder 54 to open and close with the seat 52. A valve (valve element) 64 is provided, a spindle 66 is connected to the valve 64, and a spring 82 is disposed around the spindle 66, and a space 92 above the valve 64 and a space 94 in the protection cylinder 54 are provided. When the pressure at the inlet 88 is smaller than the set pressure, the valve 64 comes into contact with the seat 52 by the force of the spring 82 to close, and the pressure at the inlet 88 is set. When the pressure exceeds the pressure, the valve 64 rises against the force of the spring 82 and is opened.
[0015]
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 (suction) 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.
[0016]
In the safety valve according to the present embodiment, no gasket or rubber is used, and all parts where a gasket or the like is conventionally used have an airtight welded joint structure.
Also, to ensure stable operation even when the primary pressure is higher than atmospheric pressure and the secondary pressure is vacuum, both the primary and secondary sides of the valve are prevented from inhaling air from entering through the valve body. 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 joined in an air-tight welded structure so that the valve 64 is not affected by thermal strain. A heat dissipating part is provided between the welding part.
[0017]
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. The heat radiating part 100a is made of a thin material so as to reduce the amount of heat transmitted during welding as the thin thick part 108.
As the bellows 68, a welded bellows that is flexible and has excellent pressure resistance and durability is used.
[0018]
Adjustment rings such as a blow-down ring 58 and an upper ring 62 are provided to improve the accuracy of the blowout pressure, the pre-leakage pressure, and the blowoff pressure. Fixing bolts for preventing rotation of these adjustment rings, that is, ring stoppers In order to enhance the sealing performance between the threaded portion of the bolt 80 and the outside air and to make it difficult to transmit heat distortion during welding, a space 110 is provided in the ring stop bolt 80 to make it difficult to transmit heat. And one end of the valve body 50 are hermetically welded. Reference numeral 112 denotes a weld.
[0019]
In the high-precision safety valve configured as described above, for example, a full-volume 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 pushes down the valve 64. Approaching the force of the spring 82, 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 valve 64 is fluid actuated port mappings is discharged to the outlet side, since the inlet pressure of the safety valve is reduced, uplift decreases, the repulsive force of the spring 82 is closed won.
[0020]
【The invention's effect】
The present invention is configured as described above, and 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, since the selection of the bellows and the adoption of a welding structure that does not easily cause thermal strain as compared with the conventional technology, a relatively inexpensive and highly accurate safety valve can be provided.
(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. The device including the primary side and the secondary side has the effect of maintaining the sealing performance .
[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 cross-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 body) 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]
50 Valve body 52 Seat (valve seat)
54 Protective cylinder 56 Cap 58 Blow down ring 60 Valve guide 62 Upper ring 64 Valve (valve element)
66 Spindle 68 Bellows 70 Guide 72 Lift limiting plate 74 Spring support 76 Adjusting screw 78 Lock nut 80 Ring stop bolt 82 Spring 84 Hex nut 86 Stud bolt 88 Inlet 90 Outlet 92, 94 Space 96 Primary container 98 Secondary container 100, 100a Heat radiating part 102 Fin structure part 104 Welded part 106 Bellows fixing member 108 Thin thick part 110 Space 112 Welded part

Claims (2)

A safety valve comprising a bellows (68) attached to the steam boiler, a vacuum pressure is secondary pressure, even pressure the primary pressure is higher than the atmospheric pressure, the primary side of the valve and secondary The safety valve has an air-tight welded joint structure so that gas does not enter from the outside through the valve body (64) on both sides, and the secondary side is welded and connected to the sealed part of the vacuum vessel. In order to enhance the height, the joint between the valve body (64) and the welded bellows in the safety valve is made airtight through the bellows fixing member (106) by using a welded bellows having flexibility, pressure resistance and excellent durability as the bellows (68). A heat radiating portion (100), which is a heat radiating fin, is provided between the valve body (64) and the welded portion (104) so as not to be affected by thermal strain. , Shutoff pressure An adjustment ring is provided to increase the accuracy.The fixing bolt is used to increase the sealing performance between the thread of the fixing bolt to prevent rotation of the adjustment ring and the outside air, and to make it difficult to transmit the thermal strain during welding. A high-precision safety valve characterized in that a space (110) for heat insulation is provided therein, and one end of a fixing bolt and a valve body (50) are hermetically welded. A safety valve comprising a bellows (68) attached to the steam boiler, a vacuum pressure is secondary pressure, even pressure the primary pressure is higher than the atmospheric pressure, the primary side of the valve and secondary The safety valve has an air-tight welded joint structure so that gas does not enter from the outside through the valve body (64) on both sides, and the secondary side is welded and connected to the sealed part of the vacuum vessel. In order to enhance the height, the joint between the valve body (64) and the welded bellows in the safety valve is made airtight through the bellows fixing member (106) by using a welded bellows having flexibility, pressure resistance and excellent durability as the bellows (68). And a heat dissipating part (100a), which is a thin thick part (108), is provided between the valve body (64) and the welded part (104) so as not to be affected by thermal distortion. , Before leak pressure, In order to increase the accuracy of the stop pressure, an adjustment ring is provided to improve the sealing between the thread of the fixing bolt for preventing rotation of the adjustment ring and the outside air, and to make it difficult to transmit thermal distortion during welding. A high-precision safety valve characterized in that a heat insulating space (110) is provided in a fixing bolt and one end of the fixing bolt and the valve body (50) are hermetically welded.

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