JPH01135973A - Excess flow inhibiting valve - Google Patents

Abstract

PURPOSE:To prevent blocking due to magnetizing action of sludge by detecting a pressure of fluid in an excess flow inhibiting valve using not a magnetic but an electric means. CONSTITUTION:An excess flow inhibiting valve 30, moving a poppet 37 to the downstream side by a differential pressure between the upstream and the downstream of the poppet 37, throttles a flow path. Between a spring 38, holding the poppet 37 of this excess flow inhibiting valve 39, and a wall part of a valve main unit 31 supporting the spring 38, a pressure detecting element 45 is arranged. And when the poppet 37 is moved to the downstream side by the differential pressure, tension of the spring 38, compressed by the poppet 37, is applied to the pressure detecting element 45 in addition to a pressure of fluid in the normal time. As the result, an electric signal is transmitted to a control chamber so as to change larger as compared with that in the normal time, and by detecting this change, the valve is displayed to be placed in a closing condition.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an overflow prevention valve, which is particularly used as an isolation valve for instrumentation of a nuclear reactor containment vessel, and which is suitable for improving the function as a containment vessel boundary. Regarding the blocking valve.

[Conventional technology]

In the reactor containment vessel of a nuclear power plant, as shown in Figs. 2 and 3, the instrumentation detection pipe 2 of the high pressure line from the reactor 1 passes through a penetration 4 installed in the containment vessel 3. , is connected to an instrument 5 outside the containment vessel.

This instrumentation detection pipe 2 has a manual isolation valve 6 at the outlet of the penetration 4 to isolate the instrument 5 side from the reactor 1, a broken detection pipe 2 on the downstream side, and an instrumentation valve 7 around the instrument 5. An overflow control valve 8 is installed to prevent loss of radioactive secondary coolant within the reactor 1 in the event of an accident such as a leak or damage to the instrument 5.

These manual isolation valves 6 and overflow prevention valves 8 act as pressure barriers and form containment vessel boundaries in the event of a loss of coolant accident. Technical standards require that it can be confirmed.

As shown in FIG. 4, the overflow prevention valve 8 has a check valve m side 12 having a poppet 10 and a spring 11 in the valve body 9, and the poppet 10 of the check valve mechanism 12 is normally closed. is held on the upstream side by the spring 11, and in the event of an accident such as the aforementioned rupture of the instrumentation pipe 2, a flow is generated in the instrumentation pipe 2 which has been in a blocked state, thereby reducing the difference between the upstream and downstream sides of the poppet 10. When pressure is generated, this differential pressure causes the poppet 10 to move downstream against the spring 11, causing the valve body 1 to move toward the downstream side.
4 is placed in contact with the valve seat 15, the flow path 13 is closed, and the area after the excessive flow prevention valve is isolated.

In addition, the conventional excessive flow prevention valve 8 functions as a valve opening/closing display mechanism.
The poppet 10 housed in the valve body 9 is made of a permanent magnet, and when the permanent magnet of the poppet 10 moves, its magnetic force turns on and off the contacts of the limit switch 16 attached to the valve body 9, and the contact is turned on and off in the control room. The open/closed status of the valve is displayed.

By the way, the liquid in the overflow prevention valve 8 and the instrumentation piping 2 is a stationary fluid, and it is conceivable that sludge is accumulated in the overflow prevention valve 8 and the instrumentation piping 2.

This accumulated sludge is removed from the poppet 10 inside the valve body 9.
It is magnetized by the magnetic force of the valve body 9 and the poppet 10, and may clog the gap between the valve body 9 and the poppet 10, which may impede pressure propagation and opening/closing of the valve body 14.

Therefore, the instrumentation piping 2 and overflow prevention valve 8 are periodically flushed from the instrument 5 side to return the sludge that has accumulated inside to the reactor 1 side, but due to magnetized sludge, it is not completely discharged. However, a considerable amount of sludge adheres to the bovet 10. Furthermore, during the isolation operation, sludge may become trapped between the valve body 14 and the valve seat 15, causing seat leakage and inhibiting the isolation function of the valve, leading to the release of coolant. Since the number of overflow prevention valves 8 is enormous, it is necessary to maintain the isolation function with great effort and time.

Japanese Patent Laid-Open No. 61-6597 discloses a prior art related to an overflow prevention valve that improves the above problem, allows easy removal of sludge inside the valve by flushing, etc., and has higher reliability.
There is No. 8.

This conventional technology does not use magnetic force in the check valve m-ellipse or valve opening/closing display mechanism, but by installing a pressure detector using a bellows and spring on the downstream side of the valve seat, it is possible to prevent clogging in the valve due to magnetization of sludge. We are trying to prevent this.

That is, in FIG. 5, this prior art overflow prevention valve 17
stopped using a permanent magnet in the poppet 10 of the check valve mechanism 12, and therefore did not install the limit switch 16, but instead installed a bellows 18 and a pressure receiving part 19 on the downstream side of the valve seat 15.
, a valve opening/closing display mechanism 21 consisting of a spring 20 and the like is attached.

In this excessive flow prevention valve 17, normally, the valve seat 15
Since there is no pressure difference between the upstream and downstream sides, the poppet 10 is pressed upstream by the spring 11, and the flow path 13 is in an open state. Therefore, the pressure in the reactor 1 is transmitted to the meter 5 through the valve internal flow path 13, and also presses the pressure receiving part 19 of the valve opening/closing display mechanism 21, pushing up the switch rod 22. When the switch rod 22 is pushed up, the contacts of the switch 23 are opened, and a signal indicating that the valve is open is sent to the control room.

On the other hand, if there is a pipe rupture or the like on the downstream side of the overflow prevention valve 17, a pressure difference will be generated before and after the poppet 10, a force will act to push the poppet 10 downstream, and the valve body 14 will press against the valve seat 15. When touched, the valve becomes closed.

As a result, the pressure on the downstream side of the poppet 10 is reduced, and the pressure receiving part 19 and the switch rod 22, which had been pressed by the liquid in the valve, are pushed into the valve by the action of the spring 20, so that the contact of the switch 23 is turned on, and the valve is closed. Displays the status.

In this valve opening/closing display mechanism 21, since the pressure receiving part 19 and the switch rod 22 are movable parts, a gap is required between the pressure receiving part 19 and its accommodation device 24, and in order to seal the inside and outside of the valve. This gap must be sealed,
The bellows 18 described above is provided for this purpose, and the bellows 18 is connected to the pressure receiving part 19 and the pressure receiving part storage device 2.
4 and seals the gap between them.

[Problem that the invention seeks to solve]

However, in the overflow prevention valve 17 of the prior art described above, there were the following problems regarding the valve opening/closing display mechanism 21.

In other words, this valve acts as a pressure barrier and forms a containment vessel boundary in the event of a loss of coolant accident, and is therefore required to have high reliability. In the conventional technology, the bellows 18 is used to seal the inside and outside of the valve to improve reliability as a containment vessel boundary, but the fluid inside the overflow prevention valve 17 is at high temperature and high pressure. If the bellows 18 is damaged, the fluid in the excessive flow prevention valve 17 will pass through the gap between the pressure receiving part 19 and the pressure receiving part storage device 24 and be released to the outside of the excessive flow prevention valve 17, reducing reliability. There was a problem.

If the bellows 18 is designed to be suitable for the conditions of driftwood in order to ensure reliability, it is very difficult to make it structurally compact, and the shape of the overflow prevention valve 17 becomes large.

By the way, as shown in FIG. 3, the instrumentation detection piping 2 is
A plurality of detection pipes 4 extend from each detection pipe 2, and the manual isolation valve 6 and the overflow prevention valve 7 are attached to each detection pipe 2. Therefore, since the installation space is limited, increasing the size of the excessive flow prevention valve 17 poses a major obstacle in terms of arrangement.

An object of the present invention is to provide a highly reliable overflow prevention valve that can prevent clogging due to the magnetization of sludge and satisfy the requirements for a containment vessel boundary.

[Means for solving problems]

The above object is achieved by an overflow prevention valve characterized in that a pressure detection element is disposed within the valve body and the pressure within the valve body is electrically detected.

[Effect]

Since there is no need to use a permanent magnet in the poppet, clogging in the valve due to magnetization of sludge does not occur. In addition, since pressure changes are electrically detected by a pressure detection element, the only thing that passes through the inside and outside of the valve is a cable that transmits the detected pressure to the outside as an electrical signal.For this reason, conventionally, the pressure receiving part was made into a movable part. This eliminates the need for gaps that would otherwise be required, and the reliability of the containment vessel as a balantry can be improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, the overflow prevention valve of the present invention is generally designated 3.
0, the excessive flow prevention valve 30 has a valve body 31 and a valve body 3.
1 and a check valve mechanism 32 located within the valve. The valve body 31 is formed with an upstream flow path 34 and a downstream flow path 35 that are partitioned by a wall 33, and the wall 33 is formed with a flow path 36 that is controlled to open and close by a check valve mechanism 32. There is.

The check valve flI32 has a poppet 37 and a spring 38 disposed in the flow path 34, one end of the spring 38 engages with the bove yt 37, aS is supported by the wall #33, and the poppet 37 A spring 38 normally holds it on the upstream side. A valve body 39 is provided at the tip of the poppet 37, and a valve seat 40 on which the valve body 39 touches is formed in the wall portion 33.

A passage 42 that is opened and closed by a needle valve 41 is also formed between the upstream passage 34 and the downstream passage 35 of the valve body 31 . The needle valve 41 is manually operated by a handle 43. The needle valve 4.1 and the passage 42 are connected to the needle valve 4.1 when the excessive flow prevention valve 30 is opened in the event of an accident and when the operation is resumed.
This is to open the passage 42 and bring the pressures of the streams 134 and 35 to the same pressure, thereby returning the valve to its open state.

The overflow prevention valve 30 also includes a valve opening/closing display mechanism 44 for checking whether the check valve 32 is open or closed.

The valve opening/closing display mechanism 44 has a pressure detection element 45 disposed between the spring 38 and the wall 33 of the valve body 31 that supports the spring 38, and this pressure detection element 45 may be of a semiconductor type or a strain gauge type. It converts the detected pressure into a change in electrical resistance, and extracts the change in resistance as an electrical signal. A cable 46 for transmitting the electric signal to the outside is connected to the pressure detection element 45.
A cable 46 passes through the valve body 31 and is connected to a preamplifier unit 47 installed outside the valve body 31. The preamplifier unit 47 is further connected to a cable 49 connected to a terminal block 48 .

In order to maintain airtightness at the part where the cable 46 passes through the valve body 31, which is the inside and outside penetration part of the excessive flow prevention valve 30, and to seal the inside and outside of the valve, there is a small gap between the cable 46 and the valve body 31. A hermetic seal is applied to the gap.

Note that 50 is a stopper of the poppet 37.

In the excessive flow prevention valve 30 configured in this way, since there is normally no pressure difference between the upstream and downstream sides of the poppet 37, the poppet 37 is pushed upstream by the spring 38, and the flow path 36 is opened. Become. At this time, the fluid pressure inside the excessive flow prevention valve 30 is constant, and no force is applied to the spring 38. Therefore, the pressure applied to the pressure detection element 45 is equal to the fluid pressure inside the excessive flow prevention valve 30. The pressure detection element 45 detects this pressure, converts the change in electrical resistance of the pressure detection element 45 into an electrical signal, and sends the electrical signal to the preamplifier unit 47 via the cable 46.
After the electrical signal is amplified at 7, it is transmitted to the control room through a cable 49.

During such normal operation, since the poppet 37 in this embodiment is not a magnet, clogging in the valve due to magnetization of sludge does not occur, and pressure changes are detected electrically by the pressure detection element 45. The only thing that passes through the inside and outside of the valve is a cable 46 that transmits the detected pressure to the outside as an electrical signal. This eliminates the need for the gap that was conventionally required when the pressure receiving part was a movable part, and the part where the cable 46 passes through the valve body 31 can easily maintain its airtightness by not applying a hermetic seal. Reliability as a container boundary can be improved.

Next, if an accident such as a pipe rupture occurs on the downstream side of the overflow prevention valve 30, a pressure difference will occur between the upstream and downstream sides of the poppet 37.
This differential pressure acts to push the poppet 37 downstream,
The valve body 39 touches the valve seat 40 and closes the flow path 36. As a result, the excessive flow prevention valve 30 is brought into a closed state.

When the valve body 39 closes in this manner, the force of the spring 38 compressed by the poppet 37 is applied to the pressure detection element 45 in addition to the normal fluid pressure. Therefore, the electrical signal transmitted to the control room changes to become larger than in normal times, and by detecting this change, it is possible to indicate that the valve is in the closed state.

Furthermore, at the start of operation, the manual isolation valve 6 (see Figures 2 and 3) located upstream of the overflow prevention valve 30 is fully closed, and there is no fluid pressure between the upstream and downstream sides of the poppet 37. No voltage is applied, so the poppet 37 is pushed upstream and the flow path 36 is in an open state. In this state, neither the fluid pressure nor the pressure pressed by the spring 38 is applied to the pressure detection element 45. Therefore, the valve changes from the valve open state with normal fluid pressure to the valve closed state and is pressed by the spring 38. By configuring settings to display the valve closed state only when additional pressure is applied, and display the valve open state in other cases, it is possible to display that the valve is in the open state at the start of operation. It is possible to display the correct opening and closing of the valve.

Such an advantage cannot be obtained with the conventional excessive flow prevention valve 17 shown in FIG. The manual isolation valve 6 on the upstream side of the blocking valve 17 is in a fully closed state, and no fluid pressure is applied to open the valves upstream or downstream of the poppet 10, so the poppet 10 is pushed upstream and the flow path is closed. 13 is in an open state, but in this state, pressure is not applied to the pressure receiving part 19 of the valve opening/closing display mechanism 21 located downstream of the poppet 10, and the switch rod 22 remains lowered, and the switch 23 The contacts remain closed. Therefore, at this time, in the control room,
This means that the valve is displayed as closed, and the actual open/closed state of the valve does not match the open/closed display in the control room.

According to this embodiment, such a discrepancy between the actual valve opening/closing state and the opening/closing display in the control room does not occur, and the correct valve opening/closing display can always be displayed.

As described above, according to this embodiment, the check valve mechanism 3
2 and the valve opening/closing display Rm44 does not use magnetic force, so there is no clogging caused by the magnetization of sludge, and the valve is reliable.
In addition, since the pressure is detected electrically by the pressure detection element 45, the airtightness of the overflow prevention valve can be improved, and the reliability as a containment vessel boundary can be improved. Since the valve is placed at a position where the pressure of the spring 38 can also be detected, it is possible to always correctly display whether the valve is open or closed.

Furthermore, according to this embodiment, conventionally the switch is turned on and off based on a set value of fluid pressure at one point.
In contrast to the open/close detection of the valve, the pressure detection element 4
5 is used to continuously measure the fluid pressure inside the overflow prevention valve 30, it is possible to detect minute pressure fluctuations inside the overflow prevention valve 30, and various controls can be performed using this pressure information. There are some advantages that can be achieved.

Note that in the above embodiment, the pressure detection element 45 is arranged between the spring 38 and the wall 33 so that not only the fluid pressure but also the pressure pressed by the spring 38 can be detected. It may be installed at other locations where the pressure related to opening and closing of the valve can be detected, for example, on the wall of the flow path 35 on the downstream side of the valve seat 40. Even in this case, by detecting the pressure fluctuation of the fluid in the flow path 35, It is possible to detect the open/closed state of the excessive flow prevention valve 30, and at the same time, it is possible to prevent clogging due to the magnetization of sludge and to improve reliability as a containment vessel boundary by ensuring airtightness.

〔Effect of the invention〕

As is clear from the above, according to the present invention, clogging due to sludge magnetization can be prevented, reliable valve operation can be expected, and the airtightness of the overflow prevention valve is improved, making it suitable for use as a containment vessel boundary. Reliability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an overflow control valve according to an embodiment of the present invention, FIG. 2 is a schematic diagram of a detection line to which the overflow prevention valve is installed, and FIGS. b) and (c)
are a top view, a side view, and an end view showing the installation status of the manual isolation valve and excessive flow prevention valve on the penetration outlet side of the detection line, respectively, and Fig. 4 is a cross-sectional view of the conventional excessive flow prevention valve. FIG. 5 is a sectional view of another conventional overflow prevention valve. Explanation of symbols 30... Excess flow prevention valve 31... Valve body 32...
・Check valve mechanism 33...Wall part 34.35.36.
...Flow path 37...Poppet 38...Spring 45...
Pressure detection element 46...Gable Applicant Hitachi, Ltd. Agent Patent Attorney Haruhi Yuzuru 30---Transient flow prevention valve 31-111 Valve body 32---Check valve 11$! 33---One wall part 34, 35, 36---Flow path 37---Poppet 38---Spring 45---One pressure detection element 46---Cable Figure 3 (a) package] lb
F3

Claims (2)

[Claims] (1) It has a valve body, a poppet and a spring arranged in a flow path within the valve body.Usually, the poppet is held on the upstream side of the flow path by a spring, and when a pressure difference occurs between the upstream and downstream sides of the poppet, In an overflow prevention valve equipped with a check valve mechanism that moves the poppet downstream based on the differential pressure, a pressure detection element is placed inside the valve body, and this pressure detection element electrically detects the pressure inside the valve body. An overflow prevention valve characterized in that: (2) The overflow prevention valve according to claim 1, wherein the pressure detection element is disposed between a spring and a wall of the valve body that supports the spring.