JPH08121626A - Main steam relief safety valve - Google Patents

Abstract

PURPOSE: To provide a main steam relief safety valve which has been miniaturized, excellent in the maintenance workability, capable of increasing the capacity, difficult to cause the seat leak, and has been improved in the reliability. CONSTITUTION: A main steam relief safety valve is provided in a main steam tube 8 of a power station, and provided with the safety valve function and the relief valve function, and a valve seat 3 is provided in a valve box 1 connected to the main steam tube 8. A valve element 2 is pressed against this valve seat 3 by a valve rod 4 and the steam in the main steam tube 8 is sealed by the valve element 2 together with the valve seat 3. The valve box 1 is integrated with a steam pressure cylinder 30, and the energizing force of the spring 13 is applied in the valve closing direction through a steam pressure cylinder shaft 35. One end of a lever 18 is connected to the valve rod 4 and the other end is connected to the steam pressure cylinder shaft 35 respectively, and the leverage is made with a support point 29 of rotation fitted to the position close to the middle as the fulcrum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main steam relief safety valve used in a main steam pipe of a power plant.

[0002]

2. Description of the Related Art Generally, in a boiling water nuclear reactor (BWR) plant, a reactor pressure vessel is directly connected to a steam turbine through four main steam pipes, and the reactor pressure rises on each main steam pipe. Sometimes it has a main steam relief valve that allows high temperature, high pressure steam to escape to the suppression chamber.

FIG. 17 is a longitudinal sectional view showing a conventional general main steam relief safety valve. The safety valve shown in FIG. 17 includes a valve box 1 which is a pressure container, a valve body 2, a valve seat 3, and a valve rod 4 for pressing the valve body 2 against the valve seat 3. In the main steam relief safety valve, the valve body 2 always closes the first passage 5 and the second passage 6. In this case, as shown in FIG. 17, the first passage 5 side is connected to the main steam pipe 8 via the nozzle 7, and the valve body 2 separates from the valve seat 3 to operate as a safety valve or a relief valve. At this time, the main steam that has flowed in from the first passage 5 reaches the suppression chamber through the exhaust pipe 9 and is cooled in this suppression chamber.

As shown in FIG. 18, the valve body 2 has an integral structure with a thermal disk 10 made of special steel, and moves up and down in a valve body guide 11, and in a normal state (when the valve is closed), a spring shown in FIG. The spring 13 housed in the case 12 causes the valve seat 3 to move by a spring force set to be equal to the set blowing pressure.
It is set to press against. Further, since the valve rod 4 that transmits the spring force of the spring 13 to the valve body 2 is long, the upper end portion is centered by the adjusting screw 14 on the upper portion. And as a relief valve mechanism,
When the air piston 16 provided in the air cylinder 15 is pushed upward, the lever 18 connected to the piston rod 17 pushes up the valve rod 4 on the basis of the lever principle, so that the valve body 2 is released from the valve seat 3. It has a structure that

[0005]

However, the above-described conventional main steam relief safety valve has the following problems. That is, first, since the valve is large and heavy, it is necessary to receive a reaction force of the exhaust pipe 9 when the valve is operating and to carry in / out equipment for maintenance. In addition, the primary reactor containment vessel (PC
There is a problem that the layout in V) (composite adjustment, loading / unloading space) is greatly affected. Second, the number of parts,
Since there are many fastening points, many man-hours for disassembly, assembly and maintenance are required. Further, there is also a disassembling and assembling work that requires skill, which puts a burden on the worker. Furthermore, in disassembling and assembling work, it is necessary to attach a pollution protector, and workability is poor.

Thirdly, a large spring is required because the pushing force of the internal pressure is coaxially pressed by the spring 13. Due to the size of this spring, there is a problem that the entire valve becomes large. Fourthly, since the valve rod 4 is long, the distribution of the force applied to the valve body 2 becomes non-uniform when it is eccentric, which causes a problem of leakage of the valve seat 3. Further, although the force of the air cylinder 15 at the time of pulling up the valve rod 4 is transmitted to the valve rod 4 by the lever 18 by this principle, a bending force acts on the valve rod 4 to bend the valve body 2 and There is a problem that leads to leakage of the seat 3.
Fifth, since the air cylinder 15 is provided adjacent to the upper part of the spring case 12, there is a problem that the center of gravity is high, which is disadvantageous in terms of earthquake resistance. Sixth, when the number of valves is increased to cope with the increase in capacity, a great deal of labor is required for maintenance.

For the above reasons, the main steam relief safety valve has a small spring and overall shape, has good disassembly and assembly workability at the time of regular inspection, and can be easily made into a large capacity valve.
A safety valve that is unlikely to cause seat leak has been desired.

The present invention has been made in consideration of the above circumstances, and it is an object of the present invention to provide a highly reliable main unit which is small in size, has good maintenance workability, has a large capacity, and is resistant to sheet leakage. To provide a vapor relief valve.

[0009]

In order to solve the above-mentioned problems, claim 1 of the present invention is installed in a main steam pipe of a power plant, and the steam pressure of this main steam pipe is automatically set. In the main steam relief safety valve having a safety valve function to be controlled below and a relief valve function to forcibly open the valve,
A valve box connected to the main steam pipe, a valve seat provided in the valve box, a valve body capable of sealing the steam in the main steam pipe together with the valve seat, and the valve body on the valve seat. A pushable valve rod, a vapor pressure cylinder integrally provided with the valve box, a vapor pressure piston moving in the vapor pressure cylinder, and a valve attached to the vapor pressure cylinder shaft of the vapor pressure piston to force the valve. , An air cylinder that movably accommodates the air piston, a spring that applies a biasing force in the valve closing direction through the steam pressure cylinder shaft, one end of the valve rod, and the other end of the steam pressure. And a lever constituting a lever with a fulcrum of rotation, which is connected to the cylinder shaft and is attached at a position near the middle.

According to a second aspect of the present invention, in the main steam relief safety valve according to the first aspect, instead of the steam pressure cylinder provided integrally with the valve box, this steam pressure cylinder is configured separately from the valve box to form a main steam pipe. It is characterized by being attached.

According to a third aspect of the present invention, in the main steam relief safety valve according to the first aspect, one end of the lever is a rotation fulcrum, and the other end is a fulcrum. It is characterized in that a valve rod is attached to each of the steam pressure cylinder shafts and near the intermediate position.

According to a fourth aspect of the present invention, in the main steam relief safety valve according to the first, second or third aspect, a pressure release path communicating with an exhaust pipe for releasing steam from the main steam line and a valve for opening and closing the pressure release path. And an opening / closing member that opens and closes in conjunction with the operation of the steam pressure piston.

According to a fifth aspect of the present invention, a safety valve function is provided which is installed in a main steam pipe of a power plant and automatically controls the steam pressure of the main steam pipe to be equal to or lower than a preset blowing pressure, and an exhaust pipe by forcibly opening the valve. In a main steam relief safety valve having a relief valve function for escaping steam to a valve box connected to the main steam pipe,
A valve seat provided in the valve box, a valve body capable of sealing the steam in the main steam pipe together with the valve seat, a valve rod capable of pressing the valve body against the valve seat, and an integral body with the valve box. A steam pressure cylinder, a steam pressure piston that moves in the steam pressure cylinder and is attached to the end of the valve rod, a spring that applies a biasing force in the valve closing direction through the valve rod, and the steam A first solenoid valve installed in a steam pressure path for guiding steam from the main steam pipe to the pressure cylinder; and a second solenoid valve installed in an exhaust path for guiding steam in the steam pressure cylinder to an exhaust pipe. And a control means for controlling the opening and closing of these first and second electromagnetic valves.

According to a sixth aspect of the present invention, a safety valve function is provided which is installed in a main steam pipe of a power plant and automatically controls the steam pressure of the main steam pipe to be equal to or lower than a set blowout pressure, and an exhaust pipe by forcibly opening the valve. In a main steam relief safety valve having a relief valve function for letting steam escape to a valve box connected to the main steam pipe and the exhaust pipe, a valve seat provided in the valve box, and the main steam together with the valve seat. A valve body that can seal the steam in the pipe,
A valve rod that presses the valve body against the valve seat, a spring that applies an urging force through the valve rod in the valve closing direction, an air cylinder that stores the spring and forcibly opens the valve, and a valve body of the valve body. A valve body rear piston mounted on the rear surface, a drive side rear piston mounted midway on the valve rod and having a larger steam receiving area than the valve body rear piston, the rear surface of the drive side rear piston and the exhaust pipe. And a pipe for communicating the same to make the pressure the same.

A seventh aspect of the invention is characterized in that the spring according to the first, second, third, fourth, fifth or sixth aspect is made of ceramics.

According to the present invention, a safety valve function is provided which is installed in a main steam pipe of a power plant and automatically controls the steam pressure of the main steam pipe to be equal to or lower than a preset blowout pressure, and a relief valve for forcibly opening the valve. In a main steam relief safety valve having a function, a valve box connected to the main steam pipe, a valve seat provided in the valve box, and a valve body capable of sealing the steam in the main steam pipe together with the valve seat And a valve rod capable of pressing the valve body against the valve seat, a spring acting on the valve rod in the valve closing direction through the valve rod, and a valve rod drive mechanism for driving the valve rod. The drive mechanism is arranged symmetrically with respect to the valve rod at equal distances.

According to a ninth aspect of the present invention, the valve stem drive mechanism according to the eighth aspect comprises a plurality of toggle links arranged axially symmetrically with respect to the valve stem and equidistantly, and a link drive source for driving these toggle links. It is characterized by having done.

According to a tenth aspect of the present invention, the link drive source according to the ninth aspect is provided with a roller arranged at each joint of a plurality of toggle links, and a tapered contact which is arranged so as to abut against these rollers and can drive the toggle link. And a ring formed with a portion, the ring being linearly moved to transmit a driving force to the roller to drive the plurality of toggle links.

According to the eleventh aspect of the present invention, a safety valve function is provided which is installed in a main steam pipe of a power plant and automatically controls the steam pressure of the main steam pipe to be equal to or lower than a set blowout pressure, and a relief valve for forcibly opening the valve. In a main steam relief safety valve having a function, a valve box connected to the main steam pipe, a valve seat provided in the valve box, and a valve body capable of sealing the steam in the main steam pipe together with the valve seat A valve rod capable of pressing the valve body against the valve seat; a spring acting through the valve rod in the valve closing direction to exert a biasing force; and a plurality of hollow cylindrical members arranged around the axis of the valve rod. Cylinders, a plurality of cylinder rods which are provided in these cylinders and are arranged symmetrically about the axis of the valve rods at equal distances, and a drive plate which connects these cylinder rods to the valve rods. It is characterized by

According to a twelfth aspect of the present invention, a safety valve function is provided which is installed in a main steam pipe of a power plant and automatically controls the steam pressure of the main steam pipe to be equal to or lower than a set blowing pressure, and a relief valve for forcibly opening the valve. In a main steam relief safety valve having a function, a valve box connected to the main steam pipe, a valve seat provided in the valve box, and a valve body capable of sealing the steam in the main steam pipe together with the valve seat A valve rod capable of pressing the valve body against the valve seat, a valve rod drive plate directly connected to the valve rod to move the valve rod by receiving fluid pressure, and a valve rod drive plate in the valve closing direction. A spring for applying a biasing force, a cylinder case provided with a high pressure port and a low pressure port with the valve rod drive plate as a boundary, and a direction switching valve for switching a fluid flow path to the high pressure port and the low pressure port of the cylinder case. Through this directional control valve, characterized in that a fluid pressure source for supplying fluid to the cylinder casing.

According to a thirteenth aspect of the present invention, in the main steam relief safety valve according to the twelfth aspect, instead of the spring for exerting a biasing force in the valve closing direction through the valve rod drive plate, the spring causes the valve rod to pass through the valve rod drive plate. The urging force acts in the valve opening direction, and the urging force is supplied to the valve rod drive plate by a fluid from a fluid pressure source to be pressed.

[0022]

In the first aspect, when the internal pressure of the main steam pipe rises, the valve body gradually pushes back the biasing force of the spring through the lever, and the force with which the valve body is pressed against the valve seat decreases. Then, when the internal pressure of the main steam pipe exceeds the valve opening pressure, the pushing force of the valve element becomes equal to or less than the biasing force of the steam pressure cylinder and the spring via the lever, and the valve is closed again. In this way, it functions as a safety valve. Therefore, while maintaining the function of the conventional safety valve, not all the pushing force of the valve body is pressed by the spring unlike the conventional one,
The spring can be downsized, and the valve as a whole can be downsized.

The relief valve function of forcibly opening the valve is
It can be realized by supplying air to the air cylinder. This air cylinder can be downsized as well as the spring. Furthermore, since the vapor pressure cylinder is provided integrally with the valve box, the number of parts of the vapor pressure cylinder portion can be reduced.

In the present invention, since the steam pressure cylinder is separated from the valve box and attached to the main steam pipe, the steam pressure cylinder side and the valve box side can be disassembled, inspected, maintained and reassembled separately. , Workability is improved.

According to another aspect of the present invention, one end of the lever is connected to a rotation fulcrum and the other end is connected to a steam pressure cylinder shaft, and a valve rod is attached at a position near the middle so that the steam pressure cylinder moves in a direction opposite to the valve body. Since the pressure is applied, the distance of the lever from the rotation fulcrum to the steam pressure cylinder shaft can be increased, and the biasing force of the spring via the lever can be reduced, and the steam pressure cylinder etc. can be made even smaller. You can

According to the present invention, when the steam pressure piston in the steam pressure cylinder moves to the valve open position, the opening / closing member that blocks the pressure release path from the main steam pipe to the exhaust pipe opens, and the pressure of the main steam pipe increases. Is also released from the steam pressure cylinder side. Therefore, it is possible to increase the capacity.

In the fifth aspect, when operating as a safety valve, the second solenoid valve installed in the exhaust path is closed,
The pressure of the main steam pipe is applied in the valve closing direction of the steam pressure cylinder by opening the first solenoid valve installed in the steam pressure path. When it operates as a relief valve, by closing the first solenoid valve and opening the second solenoid valve, the pressure in the steam pressure cylinder is released, and the valve body is pushed up by the main steam pressure to lift the spring. Push up to forcefully open the valve. This can eliminate the need for an air cylinder.

In the sixth aspect, the valve body rear piston and the drive side rear piston simultaneously receive the main steam pipe internal pressure, and the pressure receiving area at this time is larger in the drive side rear piston. Then, as the pressure rises, a force in the valve opening direction acts, and a biasing force of the spring acts so as to suppress this force. Therefore, the safety valve function can be realized with a small spring. Further, since the relief valve function can be realized by the air cylinder, the valve can be downsized.

In the seventh aspect, since the spring is made of ceramics, cooling of the spring is unnecessary, and the spring case can be directly fixed to the valve box.

According to the present invention, since the valve rod drive mechanism is arranged symmetrically and equidistantly with respect to the valve rod, the valve rod pulling direction coincides with the valve rod axis center, and bending load is not generated. Therefore, the reproducibility of the contact position when the valve seat and the thermal disk contact again during the relief valve operation is high, and the blowout pressure during the safety valve operation becomes constant.

According to a ninth aspect of the present invention, in the valve stem drive mechanism according to the eighth aspect, a plurality of toggle links arranged axially symmetrically to the valve stem at equal distances and a link drive source for driving these toggle links. The driving force is boosted by linearly moving the valve rod by the toggle link, and the valve rod driving force is reduced.

According to a tenth aspect of the present invention, the link drive source according to the ninth aspect is provided with rollers respectively arranged at joints of a plurality of toggle links, and a taper shape which is disposed in contact with the rollers and is capable of driving the toggle links. A ring having a contact portion is formed, and the valve rod is pulled up by linearly moving the ring and transmitting a driving force to the roller to drive the plurality of toggle links.

In this case, the angle of the tapered contact portion can be set so that the axial force of the toggle link for pulling up the valve rod is maximized, and the contact surface of the tapered contact portion is formed as a curve during movement. It is also possible to change the taper angle so as to maximize the axial force according to the angle formed by each toggle link.

According to the eleventh aspect of the present invention, a plurality of hollow cylindrical cylinders are arranged centering on the axis of the valve rod, and a plurality of cylinder rods are arranged symmetrically about the axis of the valve rod at equal distances. , Pull up the stem. Since the plurality of cylinders have a hollow cylindrical shape, it is possible to prevent variations in the direction and magnitude of the cylinder force transmitted to each cylinder rod.

According to the twelfth aspect of the present invention, since the valve stem drive plate for transmitting the driving force to the valve stem is directly connected to the valve stem, the pulling direction of the valve stem coincides with the valve stem axis, and no bending load is generated. . Therefore, the reproducibility of the contact position when the valve seat and the thermal disk contact again during the relief valve operation is high, and the blowout pressure during the safety valve operation becomes constant. In addition, since the drive system is symmetrical with respect to the axis, it is possible to improve the earthquake resistance and the dynamic reliability during an earthquake.

According to the thirteenth aspect of the present invention, the spring exerts an urging force on the valve stem in the valve opening direction via the valve stem drive plate, and supplies the fluid from the fluid pressure source to the valve stem drive plate. By pressing with the
Since the valve rod is pulled up by the urging force of the spring, the operating time during the relief valve operation is short and the response is excellent. Further, since the spring only has to push up the valve rod, the biasing force is reduced, and the size and weight can be reduced.

[0037]

Embodiments of the present invention will be described below with reference to the drawings. Note that the same or corresponding portions as those of the conventional configuration will be described using the same reference numerals as those in FIGS. 17 and 18.

1 and 2 are a longitudinal sectional view showing the structure of a first embodiment of the present invention and a diagram showing the operating principle. FIG.
In the lower part of the valve box 1, a lower surface flange 19 is provided, and the valve box 1 is mounted by the lower surface flange 19 on the base 7 of the main steam pipe 8 via a fixed seal portion (not shown). There is. A side surface flange 20 is provided on the side surface of the valve box 1, and the valve box 1 has the side surface flange 20.
Is connected to an exhaust pipe (not shown) via a fixed seal portion.

A valve seat 3 which is a steam inlet from the main steam pipe 8 is provided on the lower surface flange 19 side in the valve box 1, and above the valve seat 3 together with the valve seat 3 is inside the main steam pipe 8. The valve body 2 capable of sealing the fluid is attached so as to be vertically movable. A socket 21 for guiding the vertical movement of the valve body 2 is fixed by a fixing nut 22. A valve body guide 11 for guiding the vertical movement of the valve body 2 and the socket 21 is attached to the valve box 1. Valve 2
The socket 21 and the socket 21 are guided so as to be vertically movable by sliding on the inner surface of the valve body guide 11.

Above the valve body 2, a valve rod 4 for pressing the valve body 2 against the valve seat 3 is vertically movably attached, and the valve rod 4 is not fixed to the valve body 2 but simply The valve body 2 is pressed against the upper portion of the valve body 2. Valve stem 4 and valve box 1
A bellows 23 for sealing between them is attached between the bellows 23, and the bellows 23 enables the valve rod 4 to move in the axial direction without leaking fluid from the inside of the valve box 1.

A valve lid 24 is mounted on the upper portion of the valve box 1 through a plurality of fixed seals 25, and a constant back pressure is maintained between the valve lid 24 and the valve rod 4 even if the bellows 23 is broken. The auxiliary back pressure piston 26 is attached. The valve stem 4 has a neck bush 27 attached to the valve lid 24.
It is guided so that it can move up and down. One end of a lever 18 is pivotally supported by a pin 28 on the upper portion of the valve rod 4, and an arbitrary position in the middle of the lever 18 is, for example, not shown in a rotary fulcrum 29 fixed to the valve box 1 or the like. It is rotatably supported by sliding bearings.

A vapor pressure cylinder 30 is cast on the valve box 1,
A vapor pressure piston 31 is integrally provided adjacent to each other by machining or the like, and inside the vapor pressure cylinder 30, a vapor pressure piston 31 that moves while sliding on the inner surface thereof is disposed. A plurality of sealing materials, such as seal rings 32, for slidingly sealing the steam pressure cylinder 30 are fitted on the steam pressure piston 31. Below the steam pressure piston 31 in the steam pressure cylinder 30, a drive steam pressure path 33 for guiding the steam pressure from the main steam pipe 8 is formed integrally with the valve box 1 by machining or the like. An exhaust path 34 is formed on the upper side of the vapor pressure piston 31, and the exhaust path 34 is connected to an exhaust pipe (not shown).

A steam pressure cylinder shaft 35 is connected to the steam pressure piston 31, and a gap between the steam pressure cylinder shaft 35 and the steam pressure cylinder 30 is sealed by a sealing material such as a bellows 36 or a gland packing (not shown). . An air piston 16 and a spring 13 are attached to the vapor pressure cylinder shaft 35. The air piston 16 has a function of compressing the spring 13, and an adjusting member for adjusting the attachment position of the vapor pressure cylinder shaft 35 is provided. The spring 13 is fixed via the spring 13 so that the initial compression length of the spring 13 can be adjusted.

The air cylinder 15 has an air piston 16
Is connected to an air supply path (not shown), for example, an air pipe, in a direction in which the steam pressure cylinder shaft 35 is pressed downward. Although not shown in the drawing, the air source,
Air system devices such as backup accumulators and solenoid valves are connected. A solenoid valve (not shown) can open and close the air pipe, which is an air supply path, by remote control from a separate control room.

The spring 13 is moved by the vapor pressure cylinder shaft 35 and the air piston 16 to move the spring 13 downward.
5 is compressed between the bottom surface and the air piston 16 and is arranged so as to urge the vapor pressure cylinder shaft 35 upward.
The upper portion of the vapor pressure cylinder shaft 35 is pivotally supported by the pin 37 at the other end of the lever 18.

The steam pressure cylinder shaft 35, the valve rod 4, the rotation fulcrum 29 and the connecting position of the lever 18 and the pressure receiving area of the steam pressure piston 31 and the valve body 2 are about the rotation fulcrum 29 due to the positive main steam pressure. Is set to act in the valve opening direction. Further, although not shown, a pressure sensor, a position sensor, etc. for detecting the operation of each part of the valve are appropriately attached, and the output signal thereof is monitored in a separate control room and used for control.

Next, the operation of this embodiment will be described.

In the above-mentioned structure, in the state of use as a spring safety valve, air is not supplied to the air cylinder 15, and the valve body 2 opens and closes according to the change in pressure in the main steam pipe 8. That is, when the pressure in the main steam pipe 8 is 0,
Since the valve body 2 and the steam pressure piston 31 are not pushed up by the internal pressure of the main steam pipe 8, only the biasing force of the spring 13 acts, and the valve body 2 is moved to the valve seat 3 through the lever 18 having a lever function. Press to hold the valve closed. When the internal pressure of the main steam pipe 8 is 0, the spring 13 generates a force for pressing the valve body 2 against the valve seat 3 against the weight and frictional force of each part. Although not shown, the pressing force at this time can be set by adjusting the initial compression length of the spring 13 by the relative position adjusting portion between the vapor pressure cylinder shaft 35 and the air piston 16. The pressing force of the spring 13 against the valve seat 3 of the valve body 2 is adjusted in advance so that the valve opens due to the force in the valve opening direction due to the blowout set pressure of the main steam pipe 8 in order to function as a safety valve.

When the pressure in the main steam pipe 8 is negative, the valve body 2
Both the steam pressure piston 31 and the steam pressure piston 31 are sucked into the main steam pipe 8. At this time, since the valve body 2 and the valve rod 4 are only in contact with each other as described above, the valve body 2 does not receive the pulling force from the valve rod 4 and maintains the valve closed state. Similarly, the vapor pressure piston 31 keeps moving to the end portion of the vapor pressure cylinder 30.

When the pressure in the main steam pipe 8 is positive, both the valve body 2 and the steam pressure piston 31 are pushed up by the internal pressure. At this time, the moment around the rotation fulcrum 29 due to the main steam pressure acting on the lever 18 acts in the valve opening direction as described above. The valve opening moment due to this main steam pressure is held down by the moment due to the spring 13.
As described above, the moment generated by the spring 13 is maintained until the pressure in the main steam pipe 8 reaches the blowout set pressure.
Is pressed against the valve seat 3 to hold the valve closed state.

Further, if the internal pressure of the main steam pipe 8 increases,
The moment in the valve opening direction due to the main steam pressure acting on the lever 18 increases, the moment caused by the spring 13 is gradually pushed back, and the force pressing the valve body 2 against the valve seat 3 decreases. Then, when the internal pressure of the main steam pipe 8 exceeds the blowout set pressure, the moment in the valve opening direction due to the main steam pressure acting on the lever 18 becomes larger than the moment due to the spring 13, and the valve body 2 is pushed up from the valve seat 3. As a result, the valve is opened, and the pressure of the main steam pipe 8 is released to the exhaust pipe (not shown) through the side flange 20. Due to this pressure release, when the pressure in the main steam pipe 8 becomes equal to or lower than the blowout set pressure, the moment in the valve opening direction due to the main steam pressure acting on the lever 18 becomes smaller than the moment due to the spring 13, and the valve is closed again. Becomes In this way, it can function as a safety valve.

In order to realize the above operation, the conditions of the steam pressure cylinder shaft 35, the valve rod 4, the connection position of the rotation fulcrum 29 and the lever 18, and the pressure receiving area of the steam pressure piston 31 and the valve body 2 are as follows. As shown in FIG. 2, the internal pressure of the main steam pipe 8 is P, the pressure receiving area of the steam pressure piston 31 is A ₁ , the pressure receiving area of the valve body 2 is A ₂ , and the steam pressure cylinder shaft 35 from the rotation fulcrum 29.
The length of the lever 18 up to L ₁ and the length of the lever 18 from the rotation fulcrum 29 to the valve rod 4 to L ₂ , the frictional force of each part,
Assuming that the weight can be ignored, the moment M about the rotation fulcrum 29 due to the internal pressure P of the main steam pipe 8 acting on the lever 18 is

[Formula 1] M = PL ₂ A ₂ −PL ₁ A _{1 When the} initial setting spring force is F _sp , the rotation fulcrum 2 by the spring 13
The moment M _sp about 9 is

## EQU00002 ## M _sp = F _sp L _{1 When the} moment M _sp is larger than the moment M, the valve remains closed. The force that presses the valve body 2 against the valve seat 3 is F
Then

[Equation 3] FL ₂ = M _sp −M

[Equation 4] When the force F that presses the valve body 2 against the valve seat 3 is 0 or less, the valve body 2 is pushed up from the valve seat 3 to open the valve.
The conditions for maintaining the valve closed state are

[Formula 5] L ₁ / L ₂ · F _sp ≧ P (A ₂ −L ₁ / L ₂ · A ₁ ) Further, the conditions for opening the valve are

[Equation 6] L ₁ / L ₂ · F _sp <P (A ₂ −L ₁ / L ₂ · A ₁ ) That is, the pressure received when the valve body 2 and the steam pressure piston 31 receive the internal pressure of the main steam pipe 8. The force P (A ₂ −L ₁ / L ₂ · A) that pushes up the valve body 2 from the valve seat 3 due to the difference in area.
₁ ) increases as the internal pressure P rises, and the force L presses the valve body 2 against the valve seat 3 by the force of the spring 13.
_When it becomes larger than ₁ / L ₂ × F _sp , the valve opens.

As described above, a force corresponding to the difference between the force due to the internal pressure of the main steam pipe 8 and the force of the spring 13 which is the setting of the blowout pressure acts on the valve body 2 and functions as a safety valve. For example, A ₁ = 142.7 cm ² , A ₂ = 143 cm
² , L ₁ = 150 mm, L ₂ = 150 mm, blowoff set pressure P ₁ of the main steam pipe 8 = 8.34 MPa, force at which blowout set pressure P ₁ presses the valve body 2 against the valve seat 3 is F ₁ , If the force of the spring 13 is F _sp1 , this F _sp1 is P
_Since F ₁ is set to 0 when it is ₁ ,

(Equation 7)

(Equation 8) As described above, the spring 13 according to the configuration of the conventional example has the valve body 2
Push-up force A ₂ P ₁ = 143 × 10 ⁻⁴ × 8.34 = 1
According to the present embodiment, the safety valve can be operated with a very small spring force as compared with the case where all the 19262N are provided to be pushed back.

[0054] The spring 13, when the pressure setting range of the valve is 8.62MPa from _{6.93, F sp = P (L} 2 /
From L ₁ · A ₂ −A ₁ ), the spring force F _sp2 = 208 N when P = 6.93 MPa, the spring force F _sp3 = 259 N when P = 8.62 MPa, and the maximum lift S of the valve body 2 at this time.
Assuming that _max = 27 mm, the constant k of the spring 13 is

[Equation 9] The initial compression amount X ₀ of the spring 13 is

[Equation 10] The maximum compression amount X _max of the spring 13 is

[Equation 11] If the usable length of the spring 13 is 60, which is a free length, the spring 13
The maximum installation length of L _sp is

(Equation 12) In this way, the spring 13 has a conventional spring constant (for example, about 18).
83 N / mm), which is extremely small. In addition, the attachment length of the spring 13 can be made shorter than the conventional length (for example, about 500 mm).

The spring 13 and the vapor pressure piston 31
Stroke is expanded to L ₁ / L ₂ times the lift of the valve body 2. Therefore, the specifications of the spring 13 can be freely selected to some extent by changing the ratio of L ₁ : L ₂ and the pressure receiving area of the vapor pressure piston 31 to appropriate values. Further, the blowout pressure of the valve can be set by changing the initial pressing force of the spring 13 by an adjusting unit (not shown ₎ that changes the attachment length L _sp of the spring 13. Further, the vapor pressure cylinder 30 has a margin for moving the vapor pressure piston 31 even if the valve body 2 is seated on the valve seat 3, and therefore the valve body 2 is pressed against the valve seat 3. It is possible.

Next, when operating as a relief valve, as shown in FIG.
Air is supplied in a direction of compressing the spring 13 of the air cylinder 15 shown in FIG. As described above, this air supply is performed by opening the solenoid valve provided in the air supply line by an operation from a separate chamber (not shown). As a result, the air piston 16 in the air cylinder 15 moves downward while pushing down the spring 13. The vapor pressure cylinder shaft 35 also moves downward together with the air piston 16, and the valve rod 4 is pulled up via the lever 18. Then, the valve body 2 loses the force to be pressed against the valve seat 3 and is pushed up by the internal pressure of the main steam pipe 8. In this way, the internal pressure of the main steam pipe 8 can be released to the exhaust pipe (not shown) via the side surface flange 20. Therefore, the force required to operate the air cylinder 15 may be equal to or greater than the biasing force of the spring 13, and the air cylinder 15 can be downsized similarly to the spring 13.

When the main steam pipe 8 has a negative pressure,
The valve body 2 is attracted to the valve seat 3. At this time, the steam pressure piston 31 is also attracted to the main steam pipe 8 side, but since the valve rod 4 and the valve body 2 are only in contact with each other as described above, the valve body 2 is not affected by this and the valve opens. It will not be done.

Next, during maintenance work at the time of periodic inspection of the plant, since the steam pressure cylinder 30 is integrated with the valve box 1, the mounting portion of the steam pressure cylinder 30 becomes unnecessary, and the number of parts is reduced. In addition, the valve is small in size as a whole, and workability (disassembly, transportation, maintenance, and assembly) can be improved. As described above, in this embodiment, it is possible to reduce the size of the entire valve and improve workability while maintaining the function of the conventional relief safety valve.

As described above, according to the present embodiment, while maintaining the function of the conventional relief safety valve, the pushing force of the valve body 2 is not entirely pushed by the spring force as in the conventional case. The cylinder 15 can be downsized,
As a result, the size of the entire valve can be reduced. When increasing the diameter of the valve seat 3 in order to increase the capacity of the valve, it is possible to easily cope with the increase in the diameter of the vapor pressure cylinder 30 without increasing the size of the entire valve. It will be possible.

Further, a rotation fulcrum 29 of the lever 18 for lever-connecting the valve rod 4 and the vapor pressure cylinder 30 is provided at an arbitrary position in the middle of the lever 18, and the valve rod 4 is provided at each end of the lever 18. Since the steam pressure cylinder shaft 35 is connected to the steam pressure cylinder shaft 35, the steam pressure cylinder 30 receives the steam pressure in the same direction as the valve body 2. For this reason, the drive steam pressure path 33 for guiding the steam from the main steam pipe 8 to the steam pressure cylinder 30 can be formed to be short, which facilitates manufacturing.

Further, since the spring 13 is not mounted on the valve rod 4, the valve rod 4 can be shortened and the force applied to the valve body 2 can be made uniform. As a result, seat leak is less likely to occur, the center of gravity of the valve body is lowered, and seismic resistance is improved. Further, since the vapor pressure cylinder 30 is integrated with the valve box 1, the number of parts can be reduced, the size is reduced as a whole, and transportation and maintenance work are facilitated.

Although not shown, the steam pressure cylinder 30, the air cylinder 15 and the spring 13 are detachable from the valve box 1 so that the steam pressure cylinder 3 can be used during maintenance work.
It is also possible to maintain 0 etc. independently. This improves maintainability and reduces the weight of the valve body during transportation. Further, even if the function of the steam pressure cylinder 30 deteriorates due to wear or the like, it becomes possible to deal with it by replacing the parts.

Although not shown, instead of the spring 13,
Utilizing the spring property of the bellows 23 used for the seal part,
By installing the bellows 23, 36 of each part in the direction in which the valve body 2 is pressed against the valve seat 3, the spring 13 can be reduced or eliminated, maintenance workability can be improved, and the number of parts can be reduced.

By the way, in the above embodiment, for example,
The blowout pressure setting unit (not shown) is provided with an adjusting unit, such as a screw unit, for changing the axial length of the steam pressure cylinder shaft 35, while the steam pressure cylinder 30 has a steam of an adjustable length. By providing the pressure piston 31 with a margin that allows the movement of the pressure piston 31, the blowing pressure can be set only by adjusting the screw portion. Similarly,
The same function can be achieved by providing the valve rod 4 with the adjusting section. The adjustment unit for each of these axes can also adjust the play in operation.

Although not shown in the figure, an adjusting portion for adjusting the position of the rotation fulcrum 29 in the longitudinal direction of the lever 18 is provided, and the moment balance is adjusted by adjusting the moment balance.
It is also possible to set the blowing pressure. By interposing a cylindrical member on the inner surface of the steam pressure cylinder 30, it is possible to select a material having a small sliding resistance with the steam pressure piston 31, and the function of the steam pressure cylinder 30 is impaired. In some cases, they may be replaced.

Further, in order to guide the vertical movement of the vapor pressure cylinder shaft 35 and the valve rod 4, a linear guide (not shown) is provided to reduce the influence of the bending force due to the lever connection with the lever 18. Good. And
The connecting portions of the lever 18, the vapor pressure cylinder shaft 35, and the valve rod 4 have a structure in which they are merely in contact with each other instead of the pin 37,
Even if the lever 18 is configured so that each shaft does not pull downward, there is no problem because each shaft basically transmits only the pushing-up force to the lever 18. In this way, the number of parts of the connecting portion may be reduced.

Furthermore, the rotation fulcrum 29 may be provided on another structure in the plant, such as a pipe support, so that a large force is not applied to the valve lid 24. And
By setting the rotation fulcrum 29 that only pushes the lever 18 from above, the strength against the pushing force of each axis is improved,
In addition, the position may be adjusted easily.

Further, instead of generating an initial pressing force on the spring 13, a weight (not shown) is placed on the valve rod 4 or on the lever 18 so as to act on the valve rod 4, and the spring 13 is The length of the spring 13 may be shortened by adopting a configuration in which only the pushing force of the valve body 2 due to the rise in the internal pressure of the steam pipe 8 is pushed. And the lever 18
The setting of the blowout pressure may be made variable by adjusting the position of the counterweight attached above. Here, regarding the weight balance of each part, the valve body 2 and the valve seat 3
The initial pressing force of the valve body 2 may be generated by pressing the valve body 2 without the counterweight.

Further, in order to prevent the condensed water from accumulating inside the steam pressure cylinder 30, the driving steam pressure passage 33 is formed so as to be inclined obliquely downward and communicate with the main steam pipe 8 so that the condensed water moves downward. It may be configured to flow and return to the main steam pipe 8. Here, a path for flowing the condensed water may be separately provided.

Furthermore, the drive vapor pressure path 33 and the exhaust path 34 may be constructed by pipes. Also,
A solenoid valve, an accumulator, or other accessory equipment may be attached to the pipe to stabilize the vapor pressure supplied to the vapor pressure cylinder 30 and control the pressure.

FIG. 3 is a longitudinal sectional view of a main steam relief safety valve showing a second embodiment of the present invention. The same or corresponding parts as those of the first embodiment will be described with the same reference numerals. The same applies to each of the following examples. As shown in FIG. 3, in the present embodiment, unlike the first embodiment, the steam pressure cylinder 30, the air cylinder 15, the spring 13 and the like are attached to the main steam pipe 8 separately from the valve box 1. In such a configuration, the operation and the like are the same as those in the first embodiment.

According to this embodiment, as in the first embodiment, the spring 13 and the air cylinder 15 are downsized, the driving steam pressure path 33 is shortened, the valve body is downsized, the center of gravity is lowered, and the valve element 2 is used.
It is possible to reduce the sheet leak and increase the capacity. Since the steam pressure cylinder 30, the air cylinder 15, and the spring 13 are attached to the main steam pipe 8 independently of the valve box 1, the rotation fulcrum 29 and the steam pressure cylinder shaft 35 are provided.
Since the length of the lever 18 between them can be increased, the vapor pressure cylinder 30 and the like can be further downsized. Further, since the valve box 1 side and the steam pressure cylinder 30 side can independently perform maintenance work, workability is improved. And
Since the valve box 1 side is lighter in weight, seismic resistance is further improved.

Furthermore, without providing the vapor pressure cylinder 30,
Even if the air cylinder 15 and the spring 13 are simply placed separately, the length of the lever 18 can be made longer than that of the conventional one.
The air cylinder 15 and the spring 13 can be downsized. Since the spring 13 is not mounted on the valve body, it is possible to reduce the size of the valve body, lower the center of gravity, and reduce the seat leak of the valve body 2. Moreover, by increasing the length of the lever 18, it is possible to cope with a large capacity.

The present embodiment is not limited to the above description and, for example, the same modification as the first embodiment can be applied.

FIG. 4 is a vertical sectional view of a main steam relief safety valve showing a third embodiment of the present invention. In FIG. 4, the second
In contrast to the embodiment, the lever 18 of this embodiment has one end rotatably attached by a rotation fulcrum 29.
The valve rod 4 is attached by a pin 28 to an arbitrary position in the middle of the above, and the vapor pressure cylinder shaft 35 is attached by a pin 37 to the other end of the lever 18. Vapor pressure cylinder 3
At 0, a drive steam pressure passage 33 is formed so that the steam pressure piston 31 receives pressure in the direction opposite to the valve body 2. In such a structure, the operation is the same as that of the first embodiment.

According to the present embodiment, as in the third embodiment, the spring 13 and the air cylinder 15 are downsized, the valve body is downsized, the center of gravity is lowered, the seat leak of the valve body 2 is reduced, and the capacity is increased. It is possible to deal with. Then, similarly to the second embodiment, it is possible to improve the maintenance workability and reduce the weight of the valve box 1 side.

Further, the rotation fulcrum 29 and the steam pressure cylinder shaft 3
Since the length of the lever 18 between the five can be made longer, the steam pressure cylinder 30 and the like can be further downsized.

The present embodiment is not limited to the above description, and for example, the same modification as the first embodiment can be applied.

FIG. 5 is a longitudinal sectional view of a main steam relief safety valve showing a fourth embodiment of the present invention. In FIG. 5, the valve box 1 is mounted on the main steam pipe 8 by a lower surface flange 19,
An exhaust pipe 9 is connected to the side surface flange 20 of the valve box 1. A valve seat 13 is provided on the main steam pipe 8 side in the valve box 1. Above the valve seat 3, a valve body 2 that seals the internal pressure of the main steam pipe 8 together with the valve seat 3 is openably and closably mounted, and the valve body 2 is mounted by a valve body guide 11 mounted on the valve housing 1. The direction of movement is guided.

A valve rod 4 is connected to the valve body 2, and a spring 13 is mounted above the valve body 2 so as to press the valve body 2 downward. Above the spring 13, a vapor pressure cylinder 30 is mounted coaxially with the valve rod 4. The pressure receiving area of the vapor pressure cylinder 30 is set smaller than that of the valve body 2. To the vapor pressure cylinder 30, a drive vapor pressure passage 33 from the main vapor pipe 8 and an exhaust passage 34a from the exhaust pipe 9 are connected. The drive steam pressure path 33 is an oblique pipe for flowing the condensed water to the main steam pipe 8 side.
A solenoid valve 38 serving as a first solenoid valve and a second solenoid valve for opening and closing the drive steam pressure path 33 and the exhaust path 34a are provided.
a and 38b are provided respectively, and these solenoid valves 38
Opening / closing operations of a and 38b are controlled by a control device 49 as a control means. An exhaust path 34b that bypasses the exhaust pipe 9 is provided below the vapor pressure cylinder 30.

Next, the operation of this embodiment will be described.

In the above structure, when operating as a safety valve, the electromagnetic valve 38b on the exhaust pipe 9 side is closed and the electromagnetic valve 38a on the drive steam pipe side is opened to change the pressure of the main steam pipe 8 to the steam pressure cylinder 30. On the upper side of. The force of the steam pressure cylinder 30 and the biasing force of the spring 13 due to this pressure suppress the pushing force of the valve body 2 due to the main steam pressure.

On the other hand, when operating as a relief valve, the steam pressure cylinder 30 is closed by closing the solenoid valve 38a on the drive steam pressure path 33 side and opening the solenoid valve 38b on the exhaust pipe 9 side.
The internal pressure is released, the valve body 2 is pushed up by the main steam pressure, the spring 13 is pushed up, and the valve can be forcibly opened.

When the pressure in the main steam pipe 8 becomes negative, the valve is affected by the difference in pressure receiving area between the steam pressure piston 31 and the valve body 2, the biasing force of the spring 13, and the weight of the movable portion such as the valve body 2. The body 2 is pressed against the valve seat 3. Therefore, the valve does not open naturally.

In this way, in principle, the operation is the same as in the first embodiment, and most of the pushing force of the valve body 2 due to the internal pressure is pushed by utilizing the internal pressure of the main steam pipe 8, and only the pushing force is pushed up. Since it suffices to press the spring 13 with the spring 13, the spring 13 can be downsized. Also, the two solenoid valves 38
The valve can be forcibly opened only by opening and closing a and 38b, and the upper mechanism can be simplified.

The same effect can be obtained by making the pressure receiving area of the vapor pressure cylinder 30 the same as the pressure receiving area of the valve element 2 and keeping the vapor pressure constant by a regulator (not shown). Further, the forced opening may be performed by an air cylinder. Further, the pipes of the vapor pressure path 33 and the exhaust paths 34a and 34b are connected to the valve box 1
The spring case 12 and the spring case 12 may be integrated with each other. Further, the present embodiment is not limited to the above description, and a modification similar to the first embodiment can be applied except for the lever portion and its connecting portion.

FIGS. 6A and 6B are vertical sectional views showing the operation of the fifth embodiment of the present invention, in which the vapor pressure cylinder 3 of FIG.
The 0 side is shown. In FIGS. 6A and 6B, a pressure release path 39 is formed as a branch path in the steam pressure path 33 that guides steam to the steam pressure cylinder 30, and an exhaust path 34 that leads to an exhaust pipe (not shown). It is in communication with. An opening / closing member 40 for opening / closing the pressure release path 39 is fixed to the lower portion of the vapor pressure piston 31.

In such a structure, when the valve is opened, the opening / closing member 40 moves the vapor pressure piston 3 as shown in FIG. 6 (B).
1 moves upward with 1, the pressure release path 39 opens,
The pressure steam of the main steam pipe 8 is opened to an exhaust pipe (not shown) via the exhaust path 34. When the valve is closed, the opening / closing member 40 closes the pressure release path 39 again as shown in FIG. 6 (A).

As a result, rather than releasing the pressure of the main steam pipe 8 from the valve body 2, the pressure can be released further from the steam pressure cylinder 30 side, and the capacity can be increased. The same effect can be obtained even if each path is a pipe. The opening / closing member 40 may be in the shape of a gate valve.

7 and 8 are a longitudinal sectional view showing the structure of the sixth embodiment of the present invention and a view showing the operating principle. Figure 7
In, the valve box 1 is mounted on the main steam pipe 8 by the lower surface flange 19, and the side surface flange 20 of the valve box 1 is connected to an exhaust pipe (not shown). A valve seat 3 is provided on the side of the side surface flange 20 in the valve box 1. A valve body 2 is arranged in the valve box 1 together with the valve seat 3 so as to seal the internal pressure of the main steam pipe 8. The valve box 1 has, for example, a valve body guide rib 41 so as to support the cylindrical surface of the valve body 2 from three directions.
Is provided, and the operation direction of the valve element 2 is guided by the guide rib 41.

On the back side of the valve body 2, a valve body rear piston 4 is provided.
2 is fixed, and the valve body rear piston 42 and the valve body 2
Is fixed to one end of the valve rod 4. At the other end of the valve rod 4,
The drive-side rear piston 43 is fixed, and the drive-side rear piston 43 is guided by the sliding surface in the valve box 1 and is movable together with the valve rod 4 and the valve body 2. A bellows 23 is attached between the valve rod 4 and the valve box 1,
It is possible to move the valve rod 4 in the axial direction without leaking fluid from the inside of the valve box 1. The spring 13 and the air cylinder 15 are attached to the drive-side rear piston 43 side so as to press the valve body 2 against the valve seat 3. A bypass pipe 44 is connected to the vicinity of the mounting portion of the air cylinder 15 and the vicinity of the side surface flange 20 so that the back pressures of the valve body rear surface piston 42 and the drive side rear surface piston 43 are made uniform.

Next, the operation of this embodiment will be described.

The valve body rear surface piston 42 and the drive side rear surface piston 43 simultaneously receive the internal pressure of the main steam pipe 8. At this time, since the pressure receiving areas of the pistons 42 and 43 are different from each other, as the pressure increases, the valve rod 4 moves toward the larger pressure receiving area.
The force to press is generated. The biasing force of the spring 13 acts so as to press this force, and realizes a safety valve function. Therefore, as shown in FIG. 8, a force due to an increase in the internal pressure P is generated due to the pressure receiving area difference A ₁ -A _{2 of the} pistons 42, 43, and the force P (A ₁ -A ₂ ) is the spring force F _sp. When it becomes larger, the valve body 2 opens from the valve seat 3.

That is, the pressure receiving area A ₁ of the valve body rear surface piston 42, the pressure receiving area of the drive side rear surface piston 43 larger than this pressure receiving area A ₁ is A ₂ , the internal pressure is P, the spring force of the spring 13 is F _sp , and When the seat force is F, the following equation is obtained.

[0095]

[Equation 13] F = F _sp −P (A ₁ −A ₂ ).

[Equation 14] F _sp ≧ P (A ₁ −A ₂ ) → F ≧ 0 (closed)

[Equation 15] F _sp <P (A ₁ −A ₂ ) → F <0 (open) As described above, according to the present embodiment, it is not necessary to receive all the pushing force by the spring 13, so that the spring 13 is small. Can be converted. Similarly, a small air cylinder 1
The relief valve function can be realized with 5. The back pressure of each piston 42, 43 is equalized by the bypass pipe 44, and can cope with the pressure fluctuation in the exhaust pipe. Therefore, by dispersing the pushing-up force of the valve rod 4 due to the internal pressure above and below the valve rod 4, it is possible to achieve a safety valve function and a relief valve function equivalent to the conventional ones with a small force of the spring 13 and the air cylinder 15. .

FIG. 9 is a vertical sectional view showing the structure of the seventh embodiment of the present invention. In FIG. 9, the valve box 1 is mounted on a main steam pipe (not shown) by a lower surface flange 19, and
An exhaust pipe (not shown) is connected to the side surface flange 20. A valve seat 3 is provided on the lower surface flange 19 side in the valve box 1, and a valve body 2 for sealing the internal pressure of a main steam pipe (not shown) is arranged above the valve seat 3. The valve body 2 is guided in its operating direction by a valve body guide 11 attached to the valve box 1, and the valve rod 4
Is connected. A bellows 2 between the valve stem 4 and the valve box 1
3 is attached, and the bellows 23 makes it possible to move the valve rod 4 in the axial direction without leaking fluid from the valve box 1.

A ceramic spring 45 is provided above the valve body 2.
Is attached so as to press the valve body 2 downward, and the ceramic spring 45 is housed in the spring case 12. A lower plate 46 is attached to the lower part of the spring case 12, and the spring case 12 and the lower plate 46 are integrally fixed to the upper flange 47 of the valve box 1 by a fixing member 48, for example, a gray lock that clamps the circumference. There is.

As described above, according to the present embodiment, in order to alleviate the thermal effect of the spring, a space for cooling was required between the spring case 12 and the valve box 1 in the related art, but the ceramic spring 45 is used. By using it, the cooling space becomes unnecessary and the spring case 12 can be directly fixed to the valve box 1. Further, since the valve body guide 11 is integrated with the valve box 1, the number of parts is reduced. Therefore, in this embodiment, the number of parts can be reduced, and the amount of work during maintenance can be reduced.

10 and 11 show a main steam relief safety valve showing an eighth embodiment of the present invention. FIG. 10 (A),
In (B) and (C), a hollow columnar air cylinder 50 is arranged around the axis of the valve rod 4, and a cylinder rod 51 as an output shaft thereof is connected to a taper ring 54 having a tapered plate. The tapered plate of the tapered ring 54 is in contact with a roller 56 rotatably attached to one joint of a toggle link 55. The output link of the toggle link 55 is rotatably connected to the drive plate 58 via the joint 57 and transmits the force for pulling up the valve rod 4.

Now, when the hollow cylindrical air cylinder 50 pushes up the taper ring 54, its transmission force pushes the roller 56 outward, and the valve rod 4 is pulled up via the toggle link 55, the joint 57, and the drive plate 58. .
At this time, if the outer periphery of the roller 56 and the contact surface of the tapered plate with the roller 56 are made of a high hardness material, fretting or the like does not occur and the roller 56 does not move. This can be done by forming the roller 56 and the taper ring 54 with a high hardness material, or by depositing a high hardness material only on the contact surface. Also, if the joints of the toggle link 55 are also treated in the same manner, they will not get stuck due to fretting or the like. The amount of movement of the valve rod 4 is measured by the position detector 59 attached to the spring case 12, and the movement of the hollow cylindrical air cylinder 50 and the taper ring 54 is detected by the limit switch 60.

FIG. 10B is a sectional view taken along the line AA of FIG. 10A, in which the tapered plate of the taper ring 54 for driving the valve rod 4, the roller 56, and the toggle link 5 are shown.
5 and the joint 57 are arranged symmetrically and equidistantly with respect to the axis of the valve rod 4 at 120 ° intervals. FIG. 10C is a sectional view taken along line BB of FIG. 10A, and in FIG.
The hollow cylindrical air cylinder 50 includes a hollow disk-shaped cylinder plate 52, a cylinder case 53 that forms a high-pressure space and a low-pressure space with the cylinder plate 52 as a boundary, and a cylinder arranged at the same position as the tapered plate of the taper ring 41. Rod 5
1 and 1.

Next, the operation of this embodiment will be described.

Stroke of driving valve rod 4 and toggle link 5
11A, regarding the relationship between the length and the rotation angle of each link of FIG. 5, and the relationship between the cylinder force and the valve rod 4 driving force.
A description will be given based on (B). 11A and 11B are schematic diagrams showing the portion of the toggle link 55. Figure 11
In (A), the length 1 of the link 55a is expressed by the following equation.

[0104]

[Equation 16] However, here, L is a joint 57a, a joint 57
The distance between b, S is the lifting stroke of the valve rod 4, α is the initial angle of the link 55a (90 ° <α ≦ 180 °), and θ is the rotation angle of the link 55a when pushing up the joint 57a by the stroke S. That is, link 55
From the initial angle α of a and the rotation angle θ of the link 55a when the joint 57a is pushed up by the stroke S,
Link 55 required when pulling up only S
The length l of a is determined.

In FIG. 11B, the taper ring 54
The ratio of the push-up component force f of the valve rod 4 to the push-up component force F of is expressed by the following equation.

[0106]

[Equation 17] Here, δ is the angle of the tapered plate of the taper ring 54, and β is the initial angle of the link 55b.

As an example, L = 500 [mm], S = 30
[Mm], α = 140 [°], θ = 20 [°],
The length l of the link 55a is l = 130.9 [mm],
The ratio of the valve rod 4 pushing force component f to the taper ring 54 pushing force component F is δ = 25 in the initial posture.
The maximum f / F = 1.53 at [°], and the maximum f / F = 1.22 at δ = 15 [°] in the final posture. This boost factor depends only on α, β, δ, and
5a and the length of the link 55b, it is possible to obtain a larger value than the example shown here.

According to the valve stem drive mechanism of the main steam relief safety valve constructed as described above, the hollow cylinder-shaped air cylinder 50 which is the drive source of the valve stem 4 is arranged around the axis of the valve stem 4. At the same time, since the cylinder rods 51 are arranged axially symmetrically and equidistantly with respect to the axis of the valve rod 4, the direction and magnitude of the cylinder force transmitted to each rod do not vary,
The taper ring 54 can be pushed up evenly. Since the tapered plate of the taper ring 54 is in contact with the roller 56, the push-up force always acts on the center of the joint 57c of the toggle link 55, so that the axial force of the link for pulling up the valve rod 4 is maximized. The taper angle can be set. It is also possible to make the contact surface a curve and gradually change the taper angle so as to maximize the axial force in accordance with the angle formed by each link during movement. In addition to this, since the tapered plate is axisymmetric and equidistant to the valve rod 4, the horizontal reaction force received from the roller 56 is offset, and the taper ring 54 requires a guide for receiving a special reaction force. Not.

Finally, since the toggle link 55 is arranged symmetrically and equidistantly with respect to the axis of the valve rod 4 and the valve rod 4 is pulled up, the pulling direction coincides with the axis and the bending load is increased. Does not occur. Therefore, the reproducibility of the contact position when the valve seat 3 and the thermal disk contact again during the relief valve operation is high, and the blowout pressure during the safety valve operation becomes constant. In addition, since the drive system is symmetrical with respect to the axis, it is possible to improve the earthquake resistance and the dynamic reliability during an earthquake.

Furthermore, by linearly moving the valve rod 4 by using the toggle link 55 as the drive mechanism, the driving force is boosted and the valve rod driving force is reduced. Furthermore, since the link drive source can be arranged at an arbitrary position, the degree of freedom in design is increased when avoiding an interfering object, and the link drive source can be arranged downward as in the present embodiment, and the center of gravity is low. Therefore, the earthquake resistance is improved.

FIG. 12 is a vertical sectional view of a main steam relief safety valve showing a ninth embodiment of the present invention. In FIG. 12, a hollow cylindrical air cylinder 50 is arranged around the axis of the valve rod 4, and a cylinder rod 51a, which is an output shaft thereof, is connected to a taper ring 54 having a tapered plate.
The tapered plate of the taper ring 54 is in contact with a roller 56 rotatably attached to one joint of a toggle link 55. The output link of the toggle link 55 is rotatably connected to the drive plate 58 via the joint 57 and transmits the force for pulling up the valve rod 4.

Now, when the hollow cylindrical air cylinder 50 pushes up the taper ring 54, the transmission force pushes the roller 56 inward and toggle link 55, joint 5
7. Pull up the valve rod 4 via the drive plate 58. At this time, if the outer periphery of the roller 56 and the contact surface of the tapered plate with the roller 56 are made of a material having high hardness, fretting or the like will not occur and the movement will not be stopped. This can be done by forming the roller 56 and the taper ring 54 with a high hardness material, or by depositing a high hardness material only on the contact surface. Also, if the joints of the toggle link 55 are also treated in the same manner, they will not get stuck due to fretting or the like. The movement amount of the valve rod 4 is measured by the position detector 59 attached to the spring case 12, and the movement of the hollow cylinder-shaped air cylinder 50 and the taper ring 54 is detected by the limit switch 60. The tapered plate of the taper ring 54 that drives the valve rod 4, the roller 56, the toggle link 55, and the joint 57 are arranged axially symmetrically and equidistantly at 120 ° intervals with respect to the axis of the valve rod 4.

Next, the operation of this embodiment will be described.

Stroke of driving valve rod 4 and toggle link 5
13 (A), regarding the relationship between the length and the rotation angle of each link in FIG.
A description will be given based on (B). In FIG. 13A, the length l of the link 42a is expressed by the following equation.

[0115]

(Equation 18) However, here, L is a joint 57a, a joint 57
The distance between b, S is the lifting stroke of the valve rod 4, α is the initial angle of the link 55a (0 ° <α ≦ 90 °), and θ is the rotation angle of the link 55a when the joint 57a is pushed up by the stroke S. That is, the length 1 of the link 55a required when pulling up the valve rod 4 by the stroke S is determined from the initial angle α of the link 55a and the rotation angle θ of the link 55a when pushing up the joint 57a by the stroke S.

In FIG. 13B, the taper ring 54
The ratio of the push-up component force f of the valve rod 4 to the push-up component force F of is expressed by the following equation.

[0117]

[Formula 19] Here, δ is the angle of the tapered plate of the taper ring 54, and β is the initial angle of the link 55b. As an example,
L = 700 [mm], S = 30 [mm], α = 60 [°],
When θ = 20 [°], the length l of the link 55a is l =
The ratio of the pushing force component f of the valve rod 4 to the pushing force component F of the taper ring 54 is 120.5 [mm], and the maximum f / F = 1.
00, in the final posture: maximum f when δ = 25 [°]
/F=1.13. This boost factor depends only on α, β and δ, changes depending on the lengths of the links 55a and 55b, and it is possible to obtain a larger value than the example shown here.

According to the valve stem drive mechanism of the main steam relief safety valve constructed as described above, the hollow cylinder-shaped air cylinder 50 which is the drive source of the valve stem 4 is arranged around the axis of the valve stem 4. At the same time, since the cylinder rods 51 are arranged axially symmetrically and equidistantly with respect to the axis of the valve rod 4, the direction and magnitude of the cylinder force transmitted to each rod do not vary,
The taper ring 54 can be pushed up evenly. Since the tapered plate of the taper ring 54 is in contact with the roller 56, the push-up force always acts on the center of the joint 57c of the toggle link 55, so that the axial force of the link for pulling up the valve rod 4 is maximized. The taper angle can be set. It is also possible to make the contact surface a curve and gradually change the taper angle so as to maximize the axial force in accordance with the angle formed by each link during movement. In addition to this, since the tapered plate is axisymmetric and equidistant to the valve rod 4, the horizontal reaction force received from the roller 56 is offset, and the taper ring 54 requires a guide for receiving a special reaction force. Not.

Finally, since the toggle link 55 is arranged symmetrically and equidistantly with respect to the axis of the valve rod 4 and the valve rod 4 is pulled up, the pulling direction coincides with the axis and the bending load is increased. Does not occur. Therefore, the reproducibility of the contact position when the valve seat 3 and the thermal disk contact again during the relief valve operation is high, and the blowout pressure during the safety valve operation becomes constant. In addition, since the drive system is symmetrical with respect to the axis, it is possible to improve the earthquake resistance and the dynamic reliability during an earthquake.

Further, by linearly moving the valve rod 4 using the toggle link 55 as the drive mechanism, the driving force is boosted and the valve rod driving force is reduced. Furthermore, since the link drive source can be arranged at an arbitrary position, the degree of freedom in design is increased when avoiding an interfering object, and in the present embodiment, the link operates in the direction of contracting when pulled up, so that the space occupied by the valve is reduced. be able to. Further, since it is possible to dispose the link drive source downward, and the center of gravity is lowered, the earthquake resistance is improved.

FIG. 14 is a vertical sectional view of a main steam relief safety valve showing a tenth embodiment of the present invention. In FIG. 14, a hollow columnar air cylinder 50 is arranged around the axis of the valve rod 4 and its output shaft, a cylinder rod 51a, is arranged axially symmetrically and equidistantly at intervals of 120 ° with respect to the axis of the valve rod 4. And is connected to the drive plate 58.

Now, when pressure is applied to the hollow cylinder air cylinder 50, the cylinder rod 51 is pushed upward, and the transmission force thereof pulls up the valve rod 4 via the drive plate 58. Valve rod 4 and hollow cylindrical air cylinder 50
The amount of movement of the air cylinder 50 is measured by a position detector 59 attached to the spring case 12,
Is detected by the limit switch 60.

According to the valve stem drive mechanism of the main steam relief safety valve configured as described above, the hollow cylindrical air cylinder 50 which is the drive source of the valve stem 4 is arranged with the axis of the valve stem 4 as the center. At the same time, since the cylinder rod 51 is arranged axially symmetrically and equidistantly with respect to the axis of the valve rod 4, the pull-up direction coincides with the axis and no bending load is generated. Therefore, the reproducibility of the contact position when the valve seat 3 and the thermal disk contact again during the relief valve operation is high, and the blowout pressure during the safety valve operation becomes constant. In addition, since the drive system is symmetrical with respect to the axis, it is possible to improve the earthquake resistance and the dynamic reliability during an earthquake. In addition, the structure is simple and the weight can be reduced.

As a modified example of this embodiment, instead of the hollow cylindrical air cylinder 50, three direct acting cylinders operated by air or hydraulic pressure are axially symmetrical with respect to the axis of the valve rod 4 and 120 ° equidistant. If the valve rods 4 are arranged at intervals, the linear motion directions are aligned, and the valve rod 4 is pulled up by hydraulic pressure or the like, the structure can be further simplified and the weight can be reduced.

FIG. 15 is a vertical sectional view of a main steam relief safety valve showing an eleventh embodiment of the present invention. In FIG. 15, the valve rod drive plate 61 is directly connected and fixed to the valve rod 4, and the valve rod drive plate 61 and the valve rod 4 are normally pressed downward in the figure by the reaction force of the spring 13. In order to raise the valve rod drive plate 61 upward, the high-pressure side port 63 and the low-pressure side port 64 of the valve rod drive cylinder case 62 are connected to the direction switching valve 65 via the fluid flow path, and a hydraulic or pneumatic fluid is used. A pressure source 66 is connected.

Now, in the normal operation state, the direction switching valve 65 is at the position a, the pressures on the upper and lower sides of the valve rod drive plate 61 are equal, and both are open. During the safety valve operation, the valve is opened by the steam pressure according to the set pressing force of the spring 13. Directional switching valve 6 during relief valve operation
By switching 5 to the position b, the fluid is supplied from the fluid pressure source 66 through the high pressure side port 63, the lower side of the valve rod drive plate 61 becomes high pressure, and the valve rod 4 is pulled up. The amount of movement of the valve rod 4 is measured by the position detector 59 attached to the valve rod drive cylinder case 62, and the movement state of the valve rod 4 is detected by the limit switch 60.

According to the valve stem drive mechanism of the main steam relief safety valve configured as described above, the valve stem drive plate 61 for transmitting the driving force to the valve stem 4 is directly connected and fixed to the valve stem 4, and thus the valve stem is The pulling direction of 4 coincides with the axis of the valve rod 4 and no bending load is generated. Therefore, the reproducibility of the contact position when the valve seat 3 and the thermal disk contact again during the relief valve operation is high, and the blowout pressure during the safety valve operation becomes constant. In addition, since the drive system is symmetrical with respect to the axis, it is possible to improve the earthquake resistance and the dynamic reliability during an earthquake.

Furthermore, by integrating the spring case 12 and the cylinder case 62, the structure is simplified, the number of parts is reduced, and the size and weight are reduced. As a result, maintenance work at the time of periodic inspection is easy to perform, and maintainability is improved.

FIG. 16 is a vertical sectional view of a main steam relief safety valve showing a twelfth embodiment of the present invention. In FIG. 16, the valve stem drive plate 61 is directly connected and fixed to the valve stem 4, and the reaction force of the spring 13 tries to push the valve stem drive plate 61 and the valve stem 4 upward in the drawing. In order to generate a seat force, the high pressure side port 63,
Fluid pressure such as hydraulic pressure or pneumatic pressure is applied from the fluid pressure source 66 via the safety valve 67 and the direction switching valve 65.

Now, in the normal operation state, the directional control valve 65 is in the position a, the upper side of the valve stem drive plate 61 becomes high pressure, and the valve stem drive plate 61 and the valve stem 4 are restrained from moving upward in the figure. At the same time, the seat force is generated.
At this time, the fluid pressure P _H of the fluid pressure source 66 (normal time) is

(Equation 20) Here, Fspring1 (when the valve is closed) is the spring force when the valve is closed, F steam1 (when it is normal) is the pushing force that the valve rod 4 receives by steam, Fseat is the normal seat force, and A _p is the valve rod drive. The pressure receiving area of the plate 61.

Since the vapor pressure becomes higher than usual during the safety valve operation, the valve can be operated by setting the blowout pressure of the safety valve 67 to the following value.

[0132]

[Equation 21] Here, P _v (at the time of operating the safety valve) is the set blowout pressure of the safety valve 67, Fspring2 (at the time of operating the safety valve) is the spring force during the operation of the safety valve, and F steam2 (at the time of operating the safety valve) is the valve rod 4 due to steam during the operation of the safety valve. Push-up force received by
A _p is the pressure receiving area of the valve rod drive plate 61.

That is, during operation of the safety valve, the force pushing up the valve rod 4 by the steam pressure becomes large, and F steam2 becomes F.
steam2 (at safety valve operation)> F steam1 (normal time) + F
When the seat is reached, the valve stem drive plate 61 is pushed up, the spring force becomes Fspring2 (during safety valve operation), and the valve 2 is pushed until the pressure on the upper side of the valve stem drive plate 61 becomes Pv expressed by the above equation. Is blown up. After that, when the vapor pressure returns to the normal value, the valve body 2 is lowered and the valve is closed.

During operation of the relief valve, by switching the directional control valve 65 to the position b, both the high pressure side port 63 and the low pressure side port 64 are opened, the force pressing the valve rod drive plate 61 disappears, and the spring 13 And the valve rod 4 is pulled up by the pushing force of the steam. The movement amount of the valve rod 4 is measured by the position detector 59 attached to the valve rod drive cylinder case 62, and the movement state of the valve rod 4 is detected by the limit switch 60.

According to the valve stem drive mechanism of the main steam relief safety valve configured as described above, the effect described in the eleventh embodiment of the present invention can be obtained, and the valve stem 4 is caused not by the fluid pressure but by the spring force. Since it is pulled up, the operation time at the time of relief valve operation is short and the response is excellent.
Furthermore, since the spring 13 need only push up the valve rod 4, the spring force is reduced, and the size and weight can be reduced.

[0136]

As described above, according to the first aspect of the present invention.
According to this, since the vapor pressure cylinder is provided integrally with the valve box, the number of parts of the vapor pressure cylinder portion can be reduced, and the overall size can be reduced. In addition, the rotation fulcrum of the lever that connects the valve rod and the vapor pressure cylinder shaft is attached at a position near the middle, and the valve rod is connected to one end and the vapor pressure cylinder shaft is connected to the other end. Since the shaft receives the main steam pressure in the same direction as the valve body,
The steam path can be shortened. Also, since the valve rod and the vapor pressure cylinder shaft are connected by leverage, the valve rod can be shortened and the force applied to the valve element can be made uniform, so seat leaks are less likely to occur and the center of gravity of the entire valve is lowered, Earthquake resistance is improved.

According to the second aspect, the steam pressure cylinder is separated from the valve box and attached to the main steam pipe. Therefore, the steam pressure cylinder side and the valve box side can be disassembled, inspected, maintained and reassembled separately. The workability is improved. Further, the lever for transmitting the force can be lengthened, and the biasing force of the spring via the lever can be reduced, so that the steam pressure cylinder and the like can be further downsized. Further, it becomes possible to relatively freely provide a path for guiding the steam from the main steam pipe to the steam pressure cylinder.

According to the third aspect, one end of the lever is connected to the rotation fulcrum and the other end is connected to the vapor pressure cylinder shaft, and the valve rod is attached in the vicinity of the intermediate position so that the vapor pressure cylinder moves in the direction opposite to the valve body. Since the steam pressure is received, the distance of the lever from the rotation fulcrum to the steam pressure cylinder shaft can be lengthened, and the biasing force of the spring via the lever can be reduced, making the steam pressure cylinder, etc. smaller. be able to.

According to the fourth aspect, when the vapor pressure piston in the vapor pressure cylinder moves to the valve open position, the opening / closing member blocking the pressure release path from the main vapor pipe to the exhaust pipe opens,
The pressure of the main steam pipe is also released from the steam pressure cylinder side.
Therefore, it is possible to increase the capacity.

According to the fifth aspect, the first solenoid valve installed in the steam pressure path for guiding the steam from the main steam pipe to the steam pressure cylinder, and the exhaust path for guiding the steam in the steam pressure cylinder to the exhaust pipe. By providing the second solenoid valve installed in and the control means for controlling the opening and closing of these first and second solenoid valves,
The number of air cylinders is reduced, the number of defective parts is reduced, maintenance workability can be improved, and the valve can be miniaturized, which improves seismic resistance.

According to the sixth aspect, since the valve body rear-side piston and the driving-side rear-side piston simultaneously receive the internal pressure of the main steam pipe, it is possible to realize the safety valve function with a small spring. Further, since the relief valve function can be realized by the air cylinder, the valve can be downsized. Further, since the valve rod can be directly connected to the drive side, no lever connection is required and the number of parts can be reduced. Furthermore, since the steam is exhausted to the exhaust pipe side, the flow of the steam becomes smooth, and the steam reaction force and vibration can be reduced.

According to the seventh aspect, since the spring is made of ceramics, cooling of the spring is unnecessary, and the spring case can be directly fixed to the valve box.

According to the eighth aspect, since the valve rod drive mechanism is arranged axially symmetrically and equidistantly with respect to the valve rod, the valve rod pulling direction coincides with the valve rod axis center, and bending load is not generated. Therefore, the reproducibility of the contact position when the valve seat and the thermal disk contact again during the relief valve operation is high, and the blowout pressure during the safety valve operation becomes constant. In addition, since the drive system is symmetrical with respect to the axis, it is possible to improve the earthquake resistance and the dynamic reliability during an earthquake.

According to a ninth aspect, the valve rod drive mechanism according to the eighth aspect includes a plurality of toggle links arranged axially symmetrically with respect to the valve rod and equidistantly, and a link drive source for driving these toggle links. The driving force is boosted by linearly moving the valve rod by the toggle link, and the valve rod driving force is reduced. Further, since the link drive source can be arranged at any position, the degree of freedom in design can be increased when avoiding an interfering object.

According to the tenth aspect, the link drive source according to the ninth aspect is provided with rollers respectively arranged at joints of a plurality of toggle links, and a taper which is disposed so as to abut against these rollers and can drive the toggle links. A ring having a circular contact portion formed therein. The ring is linearly moved to transmit a driving force to the roller to drive the plurality of toggle links to pull up the valve rod.

In this case, the angle of the tapered contact portion can be set so that the axial force of the toggle link for pulling up the valve rod is maximized, and the contact surface of the tapered contact portion is made into a curve during movement. It is also possible to change the taper angle so as to maximize the axial force according to the angle formed by each toggle link.

Further, since the tapered contact portions are axially symmetric with respect to the valve rod and are equidistant from each other, the horizontal reaction forces received from the rollers are canceled out, and a special guide for pressing the ring is not required.

According to the eleventh aspect, a plurality of hollow columnar cylinders are arranged centering on the axis of the valve rod, and a plurality of cylinder rods are arranged symmetrically about the axis of the valve rod at equal distances. To pull up the valve stem. Since the plurality of cylinders have a hollow cylindrical shape, it is possible to prevent variations in the direction and magnitude of the cylinder force transmitted to each cylinder rod. As a result, the valve rod pull-up direction coincides with the valve rod axis, and no bending load is generated. Therefore, the reproducibility of the contact position when the valve seat and the thermal disk contact again during the relief valve operation is high, and the blowout pressure during the safety valve operation becomes constant. In addition, since the drive system is symmetrical with respect to the axis, it is possible to improve the earthquake resistance and the dynamic reliability during an earthquake.

According to the twelfth aspect, since the valve stem drive plate for transmitting the driving force to the valve stem is directly connected to the valve stem, the pull-up direction of the valve stem coincides with the valve stem axis, and the bending load is generated. do not do. Therefore, as in the eleventh aspect, the reproducibility of the contact position when the valve seat again contacts the thermal disk during the relief valve operation is high, and the blowout pressure during the safety valve operation becomes constant. In addition, since the drive system is symmetrical with respect to the axis, it is possible to improve the earthquake resistance and the dynamic reliability during an earthquake.

According to the thirteenth aspect, the spring exerts a biasing force on the valve stem in the valve opening direction via the valve stem drive plate,
By supplying and pressing this urging force to the valve rod drive plate from the fluid pressure source, the valve rod is pulled up not by the fluid pressure but by the urging force of the spring, so the operating time during the relief valve operation is short. Excellent responsiveness. Also, since the spring only has to push up the valve rod, the urging force is reduced,
Compact and lightweight.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a main steam relief safety valve according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the operation principle of the first embodiment.

FIG. 3 is a longitudinal sectional view showing a main steam relief safety valve according to a second embodiment of the present invention.

FIG. 4 is a vertical sectional view showing a main steam relief safety valve according to a third embodiment of the present invention.

FIG. 5 is a vertical sectional view showing a main steam relief safety valve according to a fourth embodiment of the present invention.

6 (A) and 6 (B) are longitudinal sectional views showing a main steam relief safety valve according to a fifth embodiment of the present invention.

FIG. 7 is a vertical sectional view showing a main steam relief safety valve according to a sixth embodiment of the present invention.

FIG. 8 is an explanatory diagram showing the operating principle of the sixth embodiment.

FIG. 9 is a vertical sectional view showing a main steam relief safety valve according to a seventh embodiment of the present invention.

10A is a longitudinal sectional view showing a main steam relief safety valve according to an eighth embodiment of the present invention, FIG. 10B is a sectional view taken along the line AA of FIG. 10A, and FIG. -B line sectional view.

11 (A) and (B) are schematic views showing a toggle link of a main steam relief safety valve according to an eighth embodiment of the present invention.

FIG. 12 is a longitudinal sectional view showing a main steam relief safety valve according to a ninth embodiment of the present invention.

13A and 13B are schematic diagrams showing a toggle link of a main steam relief safety valve according to a ninth embodiment of the present invention.

FIG. 14 is a longitudinal sectional view showing a main steam relief safety valve according to a tenth embodiment of the present invention.

FIG. 15 is a longitudinal sectional view showing a main steam relief safety valve according to an eleventh embodiment of the present invention.

FIG. 16 is a vertical sectional view showing a main steam relief safety valve according to a twelfth embodiment of the present invention.

FIG. 17 is a longitudinal sectional view showing a conventional main steam relief safety valve.

FIG. 18 is an enlarged vertical cross-sectional view showing a conventional main steam relief safety valve.

[Explanation of symbols]

 1 valve box 2 valve body 3 valve seat 4 valve rod 5 first passage 6 second passage 7 nozzle base 8 main steam pipe 9 exhaust pipe 10 thermal disc 11 valve disc guide 12 spring case 13 spring 14 adjusting screw 15 air Cylinder 16 Air piston 17 Piston rod 18 Lever 19 Bottom flange 20 Side flange 21 Socket 22 Fixed nut 23 Bellows 24 Valve lid 25 Fixed seal 26 Auxiliary back pressure piston 27 Neck bush 28 Pin 29 Rotation fulcrum 39 Steam pressure cylinder 31 Steam pressure piston 32 Seal ring 33 Drive steam pressure path 34 Exhaust path 35 Steam pressure cylinder shaft 36 Bellows 37 Pin 38a Electromagnetic valve (first electromagnetic valve) 38b Electromagnetic valve (second electromagnetic valve) 39 Pressure release path 40 Opening / closing member 41 Valve body Guide rib 42 Valve body rear pi Ton 43 Drive-side rear piston 44 Bypass pipe 45 Ceramics spring 46 Lower plate 47 Upper flange 48 Fixing member 49 Control device (control means) 50 Air cylinder 51 Cylinder rod 52 Cylinder plate 53 Cylinder case 54 Taper ring 55 Toggle link 56 Roller 57 Joint 58 Drive plate 59 Position detector 60 Limit switch 61 Valve rod drive plate 62 Valve rod drive cylinder case 63 High pressure side port 64 Low pressure side port 65 Directional switching valve 66 Fluid pressure source 67 Safety valve

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Nobuhiko Tanaka 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Incorporated Toshiba Research and Development Center (72) Inventor Katsumi Yamada Komukai-Toshiba, Kawasaki-shi, Kanagawa Town No. 1 Incorporated Toshiba Corporation R & D Center (72) Inventor Tetsuzo Yamamoto No. 1 Komukai Toshiba-cho, Kouki-ku, Kawasaki-shi, Kanagawa Incorporated Company Toshiba R & D Center

Claims (13)

[Claims] 1. A safety valve function which is installed in a main steam pipe of a power plant and automatically controls the steam pressure of the main steam pipe to be equal to or lower than a preset blowout pressure, and a relief valve function which forcibly opens the valve. In the main steam relief safety valve, a valve box connected to the main steam pipe, a valve seat provided in the valve box, a valve body capable of sealing the steam in the main steam pipe together with the valve seat, and the valve A valve rod capable of pressing the body against the valve seat, a vapor pressure cylinder integrally provided with the valve box, a vapor pressure piston moving in the vapor pressure cylinder, and a vapor pressure cylinder shaft of the vapor pressure piston. An air piston that is attached to forcefully open the valve, an air cylinder that movably accommodates the air piston, a spring that applies a biasing force in the valve closing direction through the steam pressure cylinder shaft, and one end of the valve rod, The other end is the steam A main steam relief safety valve, comprising: a lever that is connected to a pressure cylinder shaft and that is attached to a position near an intermediate position and that constitutes a lever with a rotation fulcrum as a fulcrum. 2. The main steam relief safety valve according to claim 1, wherein, instead of the steam pressure cylinder provided integrally with the valve box, this steam pressure cylinder is configured separately from the valve box and attached to the main steam pipe. Main steam relief safety valve featuring. 3. The main steam relief safety valve according to claim 1, wherein one end of the lever is a rotation fulcrum, instead of the mounting positions of the valve rod, the steam pressure cylinder shaft and the rotation fulcrum on the lever.
A main steam relief safety valve characterized in that the other end is connected to the steam pressure cylinder shaft, and a valve rod is attached near the middle position. 4. The main steam relief safety valve according to claim 1, 2 or 3, wherein a pressure release path communicating with an exhaust pipe for releasing steam from the main steam pipe and a steam pressure at the time of opening and closing the valve are provided. A main steam relief safety valve characterized by being provided with an opening / closing member that opens and closes in conjunction with the operation of the piston. 5. A safety valve function which is installed in a main steam pipe of a power plant and automatically controls the steam pressure of the main steam pipe to be equal to or lower than a set blowing pressure, and forcibly opens the valve to supply steam to an exhaust pipe. In a main steam relief safety valve that has a relief valve function for escaping, a valve box connected to the main steam tube, a valve seat provided in the valve box, and the steam in the main steam tube can be sealed together with the valve seat A valve body, a valve rod capable of pressing the valve body against the valve seat, a vapor pressure cylinder integrally provided with the valve box, and moving inside the vapor pressure cylinder to be attached to the end of the valve rod. A steam pressure piston, a spring acting as a biasing force in the valve closing direction through the valve rod, a first solenoid valve installed in a steam pressure path for guiding steam from the main steam pipe to the steam pressure cylinder, In the exhaust path leading the steam in the steam pressure cylinder to the exhaust pipe A main steam relief safety valve comprising a second solenoid valve installed and control means for controlling the opening and closing of these first and second solenoid valves. 6. A safety valve function which is installed in a main steam pipe of a power plant and automatically controls the steam pressure of the main steam pipe to be equal to or less than a set blowing pressure, and forcibly opens the valve to supply steam to an exhaust pipe. In a main steam relief safety valve having a relief valve function for escaping, a valve box connected to the main steam pipe and the exhaust pipe,
A valve seat provided in the valve box, a valve body capable of sealing steam in the main steam pipe together with the valve seat, a valve rod pressing the valve body against the valve seat, and a valve closing through the valve rod. A spring that exerts a biasing force in the direction, an air cylinder that stores the spring and forcibly opens the valve, a valve body rear piston that is mounted on the back surface of the valve body, and a valve that is mounted midway on the valve rod. A main feature is that it is provided with a drive-side rear piston having a steam receiving area larger than that of the body-back piston, and a pipe for communicating the rear side of the drive-side rear piston with the exhaust pipe to make the pressure the same. Steam relief safety valve. 7. The main steam relief safety valve according to claim 1, 2, 3, 4, 5 or 6, wherein the spring is made of ceramics. 8. A safety valve function which is installed in a main steam pipe of a power plant and automatically controls the steam pressure of the main steam pipe to be equal to or lower than a set blowing pressure, and a relief valve function of forcibly opening the valve. In the main steam relief safety valve having, a valve box connected to the main steam pipe, a valve seat provided in the valve box, a valve body capable of sealing the steam in the main steam pipe together with the valve seat, and A valve rod capable of pressing the valve body against the valve seat,
A spring that applies an urging force in the valve closing direction through this valve rod,
A main steam relief safety valve, comprising: a valve stem drive mechanism for driving the valve stem, wherein the valve stem drive mechanism is arranged axially symmetrically and equidistantly with respect to the valve stem. 9. The valve rod drive mechanism comprises a plurality of toggle links arranged axially symmetrically and equidistantly to the valve rod, and a link drive source for driving these toggle links. The main steam relief safety valve described in 8. 10. The link driving source comprises rollers arranged at joints of a plurality of toggle links, and a ring having a tapered contact portion arranged to abut on these rollers and capable of driving the toggle links. The main steam relief safety valve according to claim 9, wherein the main steam relief safety valve is configured to linearly move the ring to transmit a driving force to the roller to drive the plurality of toggle links. 11. A safety valve function, which is installed in a main steam pipe of a power plant and automatically controls the steam pressure of the main steam pipe to be equal to or lower than a preset blowout pressure, and a relief valve function of forcibly opening the valve to escape. In the main steam relief safety valve having, a valve box connected to the main steam pipe, a valve seat provided in the valve box, a valve body capable of sealing the steam in the main steam pipe together with the valve seat, and A valve rod capable of pressing the valve body against the valve seat, a spring acting on the valve rod in the valve closing direction through the valve rod, and a plurality of hollow cylindrical cylinders centered on the axis of the valve rod. , A plurality of cylinder rods provided on these cylinders and arranged at equal distances in axial symmetry with respect to the axis of the valve rod, and a drive plate connecting the cylinder rod and the valve rod. A main steam relief safety valve. 12. A safety valve function which is installed in a main steam pipe of a power plant and automatically controls the steam pressure of the main steam pipe to be equal to or lower than a set blowing pressure, and a relief valve function of forcibly opening the valve. In the main steam relief safety valve having, a valve box connected to the main steam pipe, a valve seat provided in the valve box, a valve body capable of sealing the steam in the main steam pipe together with the valve seat, and A valve rod that can press the valve body against the valve seat, a valve rod drive plate that is directly connected to the valve rod and moves the valve rod by receiving fluid pressure, and an urging force in the valve closing direction through the valve rod drive plate. A cylinder case provided with a high-pressure port and a low-pressure port with the acting spring, the valve rod drive plate as a boundary, a direction switching valve for switching a fluid flow path to the high-pressure port and the low-pressure port of the cylinder case, and this direction Off A main steam relief safety valve comprising: a fluid pressure source that supplies fluid to the cylinder case via a switching valve. 13. The main steam relief safety valve according to claim 12, wherein instead of a spring that applies a biasing force to the valve closing direction through the valve rod drive plate, the spring causes the valve rod to open in the valve opening direction via the valve rod drive plate. A main steam relief safety valve characterized in that, while exerting an urging force on, the urging force is supplied to a valve rod drive plate by a fluid from a fluid pressure source and pressed.