JPS6132371Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a device for detecting the flow of liquid in a transfer tube, such as liquid helium.

Generally, when liquid helium is transferred from a parent tank to a child tank, it is transferred from the stainless steel parent tank to the non-magnetic child tank via a double-layered transfer tube made of stainless steel. Rera. In this case, the outer cavity of the double tube is usually kept under a high vacuum to prevent heat transfer (conduction, radiation, convection) and to prevent liquid helium, etc., from vaporizing while moving through the transfer tube. I'm careful about that.

However, since it is a double tube made of stainless steel, it has been difficult to clearly determine whether liquid or gas is flowing.

This idea solves the above problems,
A thin superconducting wire is provided on an arbitrary cross section of the transfer tube, and the flow status of the liquid is determined by utilizing the difference in resistance value depending on the presence or absence (flow) of liquid.

The drawings will be explained below. In Figure 1,
1 is a transfer tube, 2 is a vacuum gap, 3 is a liquid feed pipe, 4 is an outer pipe wall, 5 is an inner pipe wall, 6, 7, 8 and 9 are connection terminals for electrical system lines to make the pipe airtight. Let these terminals that are currently installed be a, b, c, and d. 10 is a copper conductor wire, 11 is a superconducting wire (Nb
(niobium wire, niobium tantalum wire, etc.), 12 is an inner tube and outer tube joint (vacuum sealing section), 13 is a voltage measuring device, 14 is a voltage measurement power source, and 15 is a resistor. In Figure 2, 16 is the parent tank, 17
18 is external pressure (helium gas, etc.),
19 is an exhaust hole, 20 is liquid helium, etc.

Next, the case of transferring liquid helium or the like will be explained. If the current flowing from the power supply 14 through the resistor 15 and the terminals 6, 7, 8, and 9 (a, b, c, and d) is i, the terminal voltage V between the terminals 6 and 9 is V=i・(reb+rbc+rcd) ...(1) rab and rcd decrease at a rate of about 4%/℃ as the temperature decreases, but since rbc is a superconducting wire as mentioned above, its resistance drops sharply when it reaches its critical temperature Tc. reaches zero when the resistance in the terminal is removed.
The situation is shown in Figure 3. O in the same figure
°K is absolute zero degree. Therefore, terminals a, d,
The voltage V between 6 and 9 (shown in equation 1) is V'=i(rab+rcd)...(2). Therefore, if △V=V−V′, (1), (2)
From the formula, △V〓i・rbc...(3) From formula (3), it can be seen that if rbc〓0, then △V〓0. To put the above results concretely,
When gaseous He is moving in the liquid feed pipe 3, the temperature is much higher than Tc, so △V indicates i・rbc, but the liquid X in the liquid feed pipe 3 is much higher than Tc. If it is full, the inside of the liquid feed pipe 3 will be
Since it becomes less than Tc, a change in ΔV occurs, and it becomes possible to detect the presence or absence of liquid flow.

In addition, in the apparatus shown in FIG.
Although the DC voltage measurement power supply 14 is used as the power supply in step 3, the power supply waveform can be a sinusoidal waveform, a rectangular wave, or a triangular wave without any problem in terms of discrimination. In addition, in the same figure, the measured voltage is made up of terminals 6 and 9 (a and d), but if the structure of terminals 7 and 8 (b and c) is a double penetration type, it can be directly connected to terminals 7 and 8. , it is possible to obtain ΔV of the above equation (3). Therefore, in this case, the calculation operation (initial value erasing operation) of ΔV=V-V' in the voltage measuring device 13 is unnecessary.

Figure 2 shows how liquid helium, etc. is transferred from the parent tank to the child tank (these tanks are sometimes called deyuwa, and in any case, in this case, it means a container with an insulating structure similar to a Maho bottle. The parent deyuwa is generally made of stainless steel. This is a drawing showing the situation in which the parent tank 1 is transferred to
When external pressure 18 (preferably the same gas as the liquid, such as helium gas is preferable to air) is applied to the liquid helium 20 etc. in the tube 6, the liquid helium 20 etc. is transferred to the transfer tube 1 (the details of its structure are shown in Fig. 1). ), and is transferred to the child tank 17,
Gas such as air in the child tank 17 is expelled from the exhaust hole 19. Furthermore, since the transfer tube 1 is made of stainless steel and the fluid status inside the liquid feed tube 3 cannot be seen from the outside, it would be very convenient to have a liquid flow detection device like this one. be.

With this device, when the parent tank becomes empty, it is possible to send only gas to the child tank, vaporize the liquid helium stored in the child tank, and prevent accidents such as pushing it out of the child tank. This has practical effects such as being useful for monitoring whether the transfer of liquid helium is progressing appropriately and for monitoring deterioration of the vacuum degree of the outer tube (vacuum gap 2) of the transfer tube. Of course, this invention is also useful because it is possible to detect flows of other liquids than liquid helium.

[Brief explanation of drawings]

Fig. 1 is a structural diagram schematically showing the configuration of the liquid flow detection device of this invention, Fig. 2 is a diagram showing a transfer device for liquid helium etc. of this invention, and Fig. 3 shows the electrical resistance of the superconducting material. It is a temperature characteristic diagram. Explanation of codes, 1...Transfer tube, 2
...Vacuum gap, 3...Liquid feed pipe, 4...Outer tube wall, 5
... Inner tube wall, 6, 7, 8 and 9 ... Airtight terminals a, b, c and d, 10 ... Copper conductor wire, 11 ...
Superconducting wire, 13... Voltage measuring device.

Claims (1)

[Scope of utility model registration request] An electric system line that penetrates the double pipe line for transferring liquid perpendicularly to the pipe axis direction, and a voltage measurement mechanism that measures the voltage between both ends of the electric line are provided,
The electrical system path is constructed by forming a normal conductor between the inner pipe and the outer pipe of the double pipe, and a superconducting material inside the inner pipe, and measuring the voltage change between the two ends of the passage to detect the liquid. A liquid flow detection device characterized by detecting the flow of liquid.