JPH04236877A - Valve with leak detector - Google Patents

Abstract

PURPOSE:To mount a detector in a free direction, to reliably detect leakage of metallic sodium from a bellows, and to prevent leakage of metallic sodium to the outside by a method wherein a leak detector formed such that an electrode holding part has detecting electrodes inserted in a detecting chamber having a cooling pipe is mounted in an airtight manner on the peripheral wall of the upper space of a valve body. CONSTITUTION:When a bellows 14 is broken, metallic sodium leaks and flows in an upper space 13 of a valve body 11 and gradually gathered for filling in due course. In this case, since air escapes from a cooling pipe 8 of a leak detector 1, the metallic sodium is caused to flow to a detecting chamber 6 by means of the pressure thereof and gathered thereat The metallic sodium gathered in the detecting chamber 6 makes contact with a detecting electrode 2 and is detected by means of a terminal part 5 through a lead wire in an extension pipe 4. Meanwhile, the metallic sodium flowing in the cooling pipe 8 is cooled by a cooling pipe 8 part located outside a heat insulating material 20 and cooled to temperature lower than a solidifying point for solidification. The cooling pipe 8 is closed and outflow of the metallic sodium to the outside is prevented from occurring.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve with a leak detector installed in a flow path for liquid metal sodium (hereinafter referred to as metal sodium) used as a coolant in a fast breeder reactor.

0002

2. Description of the Related Art A conventional example of a leak detector for a valve provided in a flow path for metallic sodium is shown in FIG. In FIG. 2, a valve 10 is provided in a pipe 19 through which metallic sodium flows. In the valve 10, a valve element 17 fixed to the tip of a stem 16 provided through a gland packing 15 in the upper part of the valve body 11 isolates the inside of the valve body 11 into a lower fluid passage 12 and an upper space 13. Bellows 14
The valve body 17 has a structure in which the periphery of the valve body is sealed and attached to the central part of the body, and by raising and lowering the stem 16, the valve body 17 comes into contact with and leaves the valve seat 18, thereby opening and closing the fluid passage 12.

In the valve 10, when sodium leaked from the bellows 14 accumulates in the valve body 11 and leaks from the wall of the valve body, a conventional method for detecting the leaked sodium is to insulate the lower side of the valve 10. Material 2
0, a saucer 21 is installed in the space between the leaked metal sodium, the leaked metal sodium is collected in the saucer 21, and the leaked metal sodium is brought into contact with the detection electrode 2 installed so as to be in contact with the liquid, and the lead wire from the detection electrode 2 is connected to the lead protection pipe. 9 to the terminal portion 5 installed outside the heat insulating material 20 to detect the presence or absence of leakage of metallic sodium.

[0004] In the case of using the above-mentioned conventional leak detection means, there is a problem that if the amount of leaked sodium is large, it overflows from the receiving tray 21 and seeps into the heat insulating material 20. Further, when a large amount of sodium leaks from the gland packing 15 as when the bellows 14 breaks, it cannot be detected because it does not enter the receiving tray 21 but flows on the outer surface of the heat insulating material 20. Furthermore, the detection electrode 2 must be attached to the saucer 21 from above, and the saucer 21 must be kept horizontal to collect leaked sodium, so the pipe to which the valve 10 is connected is vertical. In such a case, installation of the tray 21 may be difficult or almost impossible.

[0005]

[Problems to be Solved by the Invention] In view of the problems of the prior art as described above, the present invention provides a system in which the mounting direction of the leak detector is not restricted and is free, and leakage of metallic sodium from the bellows can be reliably detected. Another object of the present invention is to realize a valve with a leak detector that has a function of preventing leakage to the outside even if the leakage continues.

[Configuration of the invention]

[0007]

[Means for Solving the Problems] In the valve with a leak detector of the present invention, the electrode holding part, which is connected to a terminal part through an extension tube and has a detection electrode at its tip, is arranged in a container-shaped detection chamber having a cooling pipe. The leak detector consists of inserting and attaching the
The detection chamber is attached to the peripheral wall of the upper space of the valve body of the valve via a fitting at one end of the detection chamber.

[0008]

[Operation] In the valve with a leak detector of the present invention, the metal sodium leaking from the broken bellows and filling the upper space of the valve body is guided and stored in the detection chamber using its pressure. Then, contact of the metal sodium accumulated in the detection chamber with the detection electrode is detected at the terminal portion via the lead wire in the extension tube. The cooling pipe also serves as an air vent and facilitates the introduction of leaked metallic sodium into the detection chamber. In addition, if the amount of leaked metallic sodium increases and attempts to flow out through the cooling pipe, by installing this cooling pipe outside the insulation material, the temperature of the cooling pipe can be kept below the freezing point of metallic sodium. As a result, metallic sodium solidifies and becomes occluded, preventing leakage. Note that after the metallic sodium solidifies and blocks the cooling pipe, it begins to leak from the gland packing of the valve body, but a leak detector detects the leak before the metallic sodium reaches the gland packing at the upper end of the valve body. Since it is detected and the amount of leakage from the gland packing is minute, it hardly leaks out of the valve. Also,
The surface of the solidified sodium metal reacts with moisture in the atmosphere to form an oxide film, and subsequent reactions with moisture are inhibited.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below based on embodiments shown in the drawings.

FIGS. 1(a) and 1(b) show a valve with a leak detector according to an embodiment of the present invention. As shown in Figure 1(a),
A valve element 17 fixed to the tip of a stem 16 provided through a gland packing 15 at the upper part of the valve body 11 is located at the center of the bellows 14 that isolates the inside of the valve body 11 into a lower fluid passage 12 and an upper space 13. The periphery of the valve body is sealed and attached to the valve body, and by raising and lowering the stem 16, the valve body 1
A valve 10 that opens and closes the fluid passage 12 by moving into and out of contact with a valve seat 18 is provided in a pipe 19 through which metallic sodium flows in the direction of the arrow. Note that 20 is a heat insulating material. A leak detector 1 is airtightly attached to a peripheral wall of an upper space 13 of a valve body 11 of this valve 10.

As shown in FIG. 1(b), the leak detector 1 includes a detection chamber 6 which is made of a container and has a cooling pipe 8 communicating with the inside thereof, and an electrode holding portion connected by a terminal portion 5 and an extension tube 4. 3
is attached so that the detection electrode 2 at the tip thereof is located within the detection chamber 6. This leak detector 1 includes a valve body 11 of a valve 10, as shown in FIG. 1(a).
The mounting bracket 7 at one end of the detection chamber 6 is airtightly fitted into the peripheral wall of the upper space 13 of the detection chamber 6 .

In the valve with a leak detector according to one embodiment of the present invention constructed as described above, when the bellows 14 breaks, metallic sodium leaks from the broken part and flows into the upper space 13 of the valve body 11, and then gradually It accumulates and eventually becomes full. At this time, since air escapes from the cooling pipe 8 of the leak detector 1, metallic sodium flows into the detection chamber 6 due to its pressure and accumulates therein. The metallic sodium accumulated in the detector 6 comes into contact with the detection electrode 2 and is detected at the terminal portion 5 via the lead wire in the extension tube 4. On the other hand, the metallic sodium that has flowed into the cooling pipe 8 is cooled in the part of the cooling pipe 8 installed outside the heat insulating material 20, solidifies below the freezing point, and blocks the cooling pipe 8, causing the metallic sodium to be removed from the outside of the cooling pipe 8. This prevents leakage. Note that after the metallic sodium solidifies and blocks the cooling pipe 8, it begins to leak from the gland packing 15 of the valve body 11, but at a point before the metallic sodium reaches the gland packing 15 at the upper end of the valve body 11. Since the leak is detected by the leak detector 1 and the amount of leak from the gland packing 15 is minute, it hardly leaks out of the valve. Further, the surface of the solidified metallic sodium reacts with moisture in the atmosphere to form an oxide film, and subsequent reactions with moisture are inhibited.

In the valve with a leak detector according to one embodiment of the present invention, since the leak detector 1 is attached to the valve body 11, the direction of the leak detector 1 is not restricted, and the valve is installed in the piping where the valve is installed. No matter what direction the
Leakage of metallic sodium from the bellows can be detected quickly and reliably. Furthermore, since the conventional technique does not require a saucer, it can be made smaller.

[0014]

As described in detail above, according to the present invention, the electrode holder, which is connected to the terminal portion by an extension tube and has a detection electrode at its tip, inserts the detection electrode into a container-shaped detection chamber having a cooling pipe. By realizing a valve with a leak detector in which the leak detector is attached to the peripheral wall of the upper space of the valve body of the valve via the mounting bracket at one end of the detection chamber, the bellows of the valve is Metallic sodium leaked due to the rupture can be quickly flowed into the detection chamber by utilizing the pressure and by releasing air from the cooling pipe, and can be detected at the terminal section via the lead wire when the detection electrode comes into contact with it. By placing the cooling pipe outside the insulation material,
The metallic sodium that is about to flow out solidifies and blocks the cooling pipe, preventing it from flowing out. In addition, since a leak detector is attached to the valve body, there are no restrictions on the orientation of the leak detector, and no matter what direction the piping in which the valve is installed, leaks of metallic sodium from the bellows can be quickly detected. Moreover, it can be detected reliably. Furthermore, since no saucer is required, the device can be made smaller.

[Brief explanation of the drawing]

1 shows a valve with a leak detector according to an embodiment of the present invention, FIG. 1(a) is a sectional view, and FIG. 1(b) is an enlarged schematic diagram showing the leak detector of FIG. 1(a).

FIG. 2 is a sectional view showing a conventional example of a valve leak detector.

[Explanation of symbols]

1...Leak detector 2...Detection electrode 3... Electrode holding part 4...Extension tube 5...Terminal section 6...Detection chamber 7...Mounting bracket 8...Cooling pipe 10...Valve 11...Valve body 12...Fluid passage 13...Upper space 14...Bellows 15...Ground packing 16...Stem 17... Valve body 18...Valve seat 19...Piping 20...Heat insulation material

Claims (1)

[Claims] Claim 1: The valve body is fixed to the tip of a stem that penetrates the gland packing in the upper part of the valve body. In a valve that is mounted with its surroundings sealed and in which the valve body comes into contact with and separates from the valve seat as the stem moves up and down to open and close the fluid passage, an electrode holding part that is connected to a terminal part by an extension tube and has a detection electrode at its tip is cooled. The leak detector, which is formed by inserting the detection electrode into a container-shaped detection chamber having a tube, is airtightly attached to the peripheral wall of the upper space of the valve body via a mounting bracket at one end of the detection chamber. A valve with a characteristic leak detector.