JPS6098690A - Cryostat - Google Patents

Abstract

PURPOSE:To prevent the fixing of a safety valve by a method wherein this valve is heated by blowing hot blow at the time of the releasing action thereof. CONSTITUTION:A superconductive coil 3 is dipped in liquid helium 2 in the cryostat 1, and the evaporated helium gas is recovered to a helium gas recovery device 6. When the gas pressure of the gas increases more than the fixed value, it is released through the safety valve 7 to the air and thus prevents the abnormal rise of the inner pressure. The cryostat inner pressure is introduced to a pressure detector 10, and, when the inner pressure exceeds the operating value of the valve, a blower 11 blowing hot blow to the valve is started.

Description

[Detailed description of the invention] [Technology of the invention/7)! L! f] Use of the present invention at extremely low temperatures'! '(1'Ii+
: ; i, φ (low temperature vessel (cryostat)) for immersing the coil in a cooling body, and is particularly useful for improving safety valves.

[Technical burden of the invention and its problems] 1. In general, the Mi '111 and Lu coils (hereinafter simply referred to as coils and coils) used at low temperatures are Helium gas (GHe) is generated while being immersed in electricity while maintaining an extremely low temperature.
is directed to a gas recovery device.

If the heat generation inside the cryostat increases due to a sudden cutoff of the coil current or deterioration of the coil characteristics while the coil is energized, the amount of GHe generated will also increase, and the gas recovery device may not be able to follow it, causing the internal pressure of the cryostat to increase. .

If the internal pressure of the cryostat increases abnormally, it may cause the cryostand to burst, which is dangerous, so a safety valve is normally used to release GHe into the atmosphere when the internal pressure rises abnormally.

In this way, when the internal pressure of the lyostat increases, the safety valve operates to prevent an abnormal increase, but (lHe
Moisture in the atmosphere adheres to the safety valve during release to the atmosphere and forms frost, and this 11f becomes the internal pressure I! This may become a hindrance to recovery work after the JJ issue.

FIG. 1 shows the general configuration of a cryostat with a safety valve.

In Figure 1 (:), the ultra-π1-conducting coil 3 is immersed in the LHe2 inside the cryostat 1, and the IJ Ll-1e 2 is caused by the amount of heat generated by the coil 3 and the heat input from the outside. When it evaporates, it becomes OHe 4, which is collected in the upper part of the cryostat by a helium gas recovery device (6) via a pipe (5).

When the heat generation (1j) of the coil 3 increases and the Ole pressure in the cryostat increases to a certain value, the safety valve 7 releases the atmosphere 8 (: G1-1c), which prevents the internal pressure from rising by 6'+E. .

The safety valve (III) is shown in Figure 2.

When the safety valve's 2j lower a is connected to the taimestat, (t) Ie pressure exceeds the pressure of the coil spring 7d which holds the stop spring 7C which is in contact with the oil hole 7b.]1 "Then, the stopper 7C is pressed, the through hole 7b opens, and the lower
from the atmosphere) 1υ out of the atmosphere, 2).

Release from the safety valve while the safety valve is operating (IHe ij
Since the cooling force ζ1j, which is strong against the cooling valve 7 and the machinability 5, should be exerted, the moisture in the atmosphere becomes λ11 of the amount -'I'lI.

When this: (1) adheres to the guide 7f of the stopper 7C, the internal pressure of the cryostat is repeated and the coil-by 7d
Even if a pressing force of 1 is applied, the guide 7f cannot move and the safety valve Vi is activated.

As mentioned above, in a cryostat with a conventional safety valve, after the safety valve is activated due to an abnormal increase in internal pressure, even if the internal pressure recovers (reduces), 111 is attached to the safety valve, and the safety valve itself is blocked by +1). There are things that are not done.

Therefore, even if the internal pressure of the cryostat changes, the safety valve remains open and all LHe in the cryostat is
evaporates and is released into the atmosphere.

Furthermore, if the safety valve is delayed in closing, air will be sucked into the cryostat due to the breathing effect due to temperature fluctuations over one cycle, and this may cause moisture in the air to adhere (freeze) to the coil surface υ■1.

When air is sucked into the cryostat and the safety valve is closed at t+, fc g, and LHe is re-injected, the ice that adhered to the coil 2 surface remains as it is, and the coil surface becomes Ll-1.
Since there is no heavy contact with e, the cooling effect decreases.

If the coil current is changed to θIC in this state, a so-called quench phenomenon occurs in which the temperature of the coil increases in the portion where ice has adhered and the coil changes to normal conductivity, making it unusable as a superconducting or conducting coil.

In order to stop the occurrence of the quench phenomenon, it is necessary to thoroughly re-dry the inside of the quenchiostat, which requires a great deal of time and expense.

In other words, is the safety valve immediately reclosed when the cryostat internal pressure is restored after the safety valve is activated? ~ is required, but conventional):
T? ) 37J cannot prevent the adhesion of 1' and 1, and the above-mentioned interlayer (i) is formed.

[Purpose of the invention] The present invention provides an internal pressure of a cryostat of ¥1', and after the safety valve is activated by accelerating the rise, the safety level of 51' closes instantly when the internal pressure is turned around. ,'lq to prevent unnecessary evaporation of LHe in the cryostat and intrusion of outside air.
The purpose is to have a cryostat of the same type.

[Yuzu of Invention, Kaname] Light Qzu, internal cooling! 1? 1 of 1!゛6 always L1-
In a cryostat with a safety valve for releasing gas, blow hot air to the safety valve to heat the safety valve to prevent the safety valve from becoming hard due to the safety valve.
τT1'A ll11. Equipped with a blower and a starting circuit that releases the safety valve's release operation or the abnormal pressure of the internal cooling medium to start the warm air blower plate, and this item 1 allows the safety valve to be activated after the release is zero. Re-closing 2 (this is a more detailed version of the operation).

[Embodiments of the Invention] FIG. 3 shows 11 examples of the effectiveness of the present invention. In FIG. 3, the same parts as in FIG. 1 are indicated by the same symbols.

In Fig. 3, the cryostat has two internal pressure contacts (1), and when the internal pressure exceeds the safety valve operating value, the contact 10a closes and warm air is blown to the safety valve 7. 78J
Activate D1 to send 11 roots.

When hot air is blown into the safety valve 7, the GH is activated while the safety valve is operating.
Even if the cold prison 1 effect due to e occurs, the circumference 1irl of the safety valve 7
When the internal pressure is restored, the moisture in the atmosphere is prevented from freezing, and when the internal pressure is restored, the safety valve 7 automatically closes again to prevent the release of 011e to the atmosphere and the intrusion of outside air.

In other words, this embodiment (in the configuration according to -, when the internal pressure of the cryostat recovers (reduces) after the safety valve operates, the safety valve automatically closes again, so that the release of 01le to the atmosphere) can be saved. It can also prevent large particles from entering the tattoo.

Is it possible to stop the atmospheric air from entering lSi+? - Moisture does not cure in the C1 coil, and no water freezes. 1F by KooL
) Quenching, which is the cause of a decrease in the cooling effect due to ice adhering to the coil during J1R and TLI, no longer occurs, and re-drying is no longer necessary, saving on de-11 transitions and increasing efficiency. The battle ended at 1-1.

Fig. 4 shows another implementation of ``Thursday'' (?! i 'a: Shown. The 41st N1 is the safety valve 70 operation = A1 Antler Mitswitch 12 is installed, and the limit switch 12 allows the temperature to be sent. Senki 11 is f bowrii force + 'I'fi stop me F!K is 4 buri, the third is 1 and fil
The e-slil comes from debt.

In addition, in the above embodiment, the explanation was made using the safety valve of formula 1jl) 11:, but
J) Using a safety valve of the Kiki style
If'f month 1 of J is 4101; 0 ``effect of brightness'' As explained above, according to the present invention, 1'', within F'd ((
In a cryostat, the safety valve is heated by blowing hot air into the safety-IP release 4i1) I1.1, so the safety valve is When the inner force of the inner chamber 1 returns to the positive 1.R without being stiffened due to the installation of the 1-bar, the safety valve at the 1-1 r immediately closes.

4th knowledge, the gas did not go outside ((h) inside, and the acceleration (but did not enter the i71+ inside 2) was 1(1j
The cooling effect of the cryostat can be safely maintained4)0

[Brief explanation of the drawing]

Figure 1 shows 7r: the next cryostat σ)-jrll
The configuration diagram shown in Figure 2 is shown below;
．． I4j [front view, No. 3] showing one embodiment of the present invention is shown in Fig. 1, and Fig. 4 shows another embodiment of the present invention.
2f・ru with 41'i J population showing 11. 1. Cryostand 2. Oil body helium (Llle) 3.. Introduction ii:':
2j'h coil 4... Helium gas (Utle) 5.
・Distribution percentage゛(〼 Helium gas recovery device 1
Outside air 1 () ... Point A: 1 pressure 4 sr 11.1
'<: jrll...τh1 Kite-sending kite 4 envy 12...
``Limit switch conversion'' - 1. ``Konshi Nori Chikaya Yu Cl'i or 1 person) Ji 2 Figure 4

Claims (1)

[Claims] In a cryostat that has a safety valve that releases abnormal pressure gas from the internal cooling medium, there is a hot air blower that blows hot air into the safety valve to heat the safety valve, a release operation of the safety valve, and an abnormal pressure of the internal cooling medium. (
n! A cryostat characterized by the following features: