JPS6353470B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses He as a refrigerant to generate cryogenic temperatures (liquid He temperature), and uses the cryogenic temperatures, for example, in a fatigue testing machine to examine the mechanical properties of metal materials at cryogenic temperatures. This relates to cryogenic cooling equipment.

Conventionally, various cryogenic cooling devices using He as a refrigerant have been proposed, but none of them is satisfactory in terms of being able to withstand continuous operation for a long time (several thousand hours) in practice.

In order to generate extremely low temperatures using He as a refrigerant,
It is necessary to house the cryogenic generator in a vacuum vessel with a heat shield at least at liquid nitrogen temperature levels. This heat shield used liquid nitrogen or an auxiliary refrigerator. This has the disadvantage that the device becomes complicated and the running cost increases when operated for a long time.

In addition, when He is used as a refrigerant in circulation for a long time, impurities (CO ₂ , O ₂ ,
(N ₂ , Ar, H ₂ , H ₂ O, etc.) must be prevented from entering. This is because most impurities condense or freeze in the heat exchange section and piping section during the process of obtaining extremely low temperatures, blocking the circulation path and stopping the function of the device.

On the other hand, a method is known in which He is circulated while adsorbing and removing impurities using a purification device. However, in order to improve the adsorption capacity, this method uses liquid nitrogen for cooling the adsorber and further uses He to regenerate the purification equipment, which has the drawback of high costs.

The present invention has been made in view of the above-mentioned conventional drawbacks, and its purpose is to reduce running costs by circulating He in a closed cycle, and to provide a cryogenic cooling device that can be operated continuously for a long time. It's about doing.

Next, the present invention will be explained with reference to the drawings which are one embodiment.

In the figure, 1 is the gas storage tank, on one side
It has a supply port 2 for receiving He gas from a He cylinder 3, and is connected to an isothermal compression device 4 on the other side. The isothermal compression device 4 has a cooler arranged between compressors, and after isothermally compressing He gas, sends it to the gas purification device 5.

In the gas purification device 5, the He gas passes through the cold heat recovery heat exchanger 6, the gas cooler 8, and the gas purifier 9, and then passes through the cold heat recovery heat exchanger 6 again and flows to the next step. Here, the cold heat recovery heat exchanger 6 cools the He gas from the isothermal compression device 4 using the He gas cooled by the gas cooler 8 and purified by the gas purifier 9.

The gas cooler 8 is cooled by an auxiliary refrigerator 7, and the auxiliary refrigerator 7 uses Freon, NH ₃ , etc. as a refrigerant.
It has a cooling capacity of approximately 260㎜.

Moreover, the gas refiner 9 has two adsorption cylinders 10a, 1
0b arranged in parallel. and,
The adsorption cylinders 10a and 10b use synthetic zeolite as an adsorbent and purify He gas by adsorbing H ₂ O and CO ₂ of the impurities in He, and have self-regeneration heaters 11a and 11b inside. There is. Valve 1 is provided on the inflow and outflow sides of each adsorption cylinder 10a, 10b.
2, 15, 17, 20 are provided, and each adsorption cylinder 10a, 10 is further provided via valves 14, 16, 19.
b is connected to a vacuum pump 50, and can be used by switching between purification and regeneration as appropriate depending on the operating time of each.

Note that the flow path 23 is provided to pre-cool the adsorption cylinders 10a and 10b after regeneration and before the start of purification work, and the flow exiting the cold heat recovery heat exchanger 6 is divided into two branched flows 24 and 25, one of which is The branched flow 24 of
It was brought back to .

Further, after the other branched flow 25 leaves the gas purification device 5, it becomes two further branched flows 26 and 27, and reaches the He freezing device 28.

The He refrigeration system 28 has heat exchangers 29, 30, 31, 32, 33, 34, and 35 arranged in multiple stages. It passes continuously in the opposite direction. Here, the incoming flow 26a
is a branch flow 26 that reaches a fatigue testing machine 44, which will be described later, and a return flow 26b is a flow that reaches a fatigue testing machine 44, which will be described later.
This is the return from.

Further, in the heat exchangers 30, 32, and 34, a part of the inlet side of the inflow flow 26a is branched, and the internal purifier 3
7. It passes through the expansion engine 38, which is a cold generator, and merges with the inlet side of the return flow 26b. Note that the internal purifier 37 has an activated carbon filter inside,
This removes impurities (air components) such as Ar, N ₂ and O ₂ in He.

The heat exchanger 35 in the final stage of heat exchange of the inflow stream 26a is a Joel Thomson (hereinafter referred to as JT) heat exchanger, and the following 39 is a JT valve,
This takes advantage of the JT effect. Inflow flow 26a
Internal purifiers 37a are provided at two locations in the middle of the tank.

Furthermore, the other branched flow 27 is connected to the heat exchanger 3
0,36, passes through the heat shield section 40, passes through the heat exchanger 36 again, and is heated to the He refrigerator 28.
be sent outside. The heat shield section 40 is a He refrigerator main body 4 that includes the entire cooling component therein.
It is arranged in a coil shape around the He refrigerator body 41 to heat shield the He refrigerator body 41. In addition,
An internal purifier 37a is provided between the heat exchangers 36 and 30, and a cold box 4, which is a vacuum container for insulation, is located outside the He refrigerator main body 41.
Covered by 2.

Therefore, the inlet stream 26a passes through the heat exchanger 29~
35, it exchanges heat with the return flow 26b, lowering the temperature step by step, and increasing the purity through the internal purifier 37. The He gas cooled in this manner is isenthalpically expanded to near atmospheric pressure at the JT valve 39, and is partially liquefied, resulting in a vaporized mixed state (mist). Became a mist
He exits the He freezing device 28 and enters the mist transfer pipe 43.
is guided to the fatigue testing machine 44 which is a load.

The fatigue tester 44 uses a liquid supplied from the outside.
Sealable cryogenic container 46 to store He45
and an inspection section 4 that applies test conditions to the test object 47.
8, and a recondenser 49 through which the mist flows. The He gas evaporated from the liquid He 45 is cooled by the recondenser 49 and liquefied again, thereby maintaining the inspection section 48 at the liquid He temperature (4.4〓).

He that has passed through the recondenser 49 becomes the return flow 26b and returns to the heat exchangers 35 to 29.
After exiting the He refrigerator 28 through the branch flow 2
7 and returns to the gas storage tank 1, forming a closed cycle.

In addition, 51, 52, and 53 are vacuum pumps, and the He flow path in the cold box 42 and the He refrigerator,
Degas the cryogenic container 46.

Next, the operation of the cryogenic cooling device having the above configuration will be explained.

First, the inside of the cryogenic cooling device is degassed using the vacuum pumps 50, 51, 52, and 53 to remove impurities, and then high-purity He gas is supplied from the He cylinder 3 to the gas storage tank 1 through the supply port 2. The conditions inside the gas storage tank 1 are approximately 1 atmosphere and approximately 310㎓.

He gas in gas storage tank 1 is transferred to isothermal compression device 4
The gas is compressed to about 15 to 20 atmospheres and reaches the gas purifier 5. Inside this, the He gas is cooled down to 260 °C from the cold heat recovery heat exchanger 6 through the gas cooler 8 and sent to the gas purifier 9.

As described above, the adsorption cylinders 10a and 10b of the gas purifier 9 can be used by switching between purification and regeneration by appropriately operating the valves depending on the operating time. For example, when purifying with the adsorption column 10a and regenerating with the adsorption column 10b, the valves 12, 15, 16, 1
8, 19 open, valves 13, 14, 17, 20,
21 is closed, the heater 11b is heated, and the vacuum pump 50 is operated.

Further, when the regeneration of the adsorption cylinder 10b is completed, the valves 16 and 19 are opened and the valve 21 is opened to pre-cool the adsorption cylinder 10b. Thereafter, purification can be started by closing the valves 18 and 21 and opening the valves 17 and 20.

When regenerating in the adsorption column 10a and refining in the adsorption column 10b, the above-mentioned operations may be performed by switching open/close valves that are in a symmetrical positional relationship.

As described above, He purified in the gas purifier 9
The gas is heat-exchanged in the cold heat recovery heat exchanger 6 and is heated to approximately 300
〓, from the gas purification device 5 to the He freezing device 28
sent to.

In the He refrigerator 28, first the heat exchangers 29 and 3
0, the inlet flow 26a and branch flow 27 are
The He refrigerator body 41 is heat shielded by the heat shield section 40 cooled to about 80°.

Of these, for the inflow flow 26a, the heat exchanger 3
Cool to about 5〓 by 1~35. Additionally, J.T.
The He gas is cooled to 4.4ⓓ by the valve 39, partially liquefied, and made into a mist state.

He in a mist state reaches the recondenser of the fatigue testing machine 44 from the He freezing device 28 and suppresses the vaporization of the liquid He 45 in the cryogenic container 46. Then, it becomes a return flow 26b that returns to the He refrigerator 28, passes through the inflow flow 26a while cooling it, and passes through the gas storage tank 1.
, and the above closed cycle is repeated again.

When the He refrigerator 28 starts operating, if the He refrigerator main body 41 is heat shielded by providing a pre-cooling line 54 of liquid nitrogen (approximately 80㎓) shown by the broken line in the figure, cooling effects such as shortening the pre-cooling time can be achieved. is improved.

Furthermore, if the liquid He 45 in the cryogenic container 46 is to be used repeatedly, a He gas recovery system 55 indicated by a broken line in the figure may be provided. 56 is a gas storage device, 5
7 is a high pressure compression device, and 58 is a purifier. In this case, the constant pressure high purity He gas is supplied from the gas storage 56 into the cryogenic container 46, and the cold supplied from the He freezing device 28 is transmitted via the recondenser 49, thereby producing the constant pressure high purity He gas. is sequentially turned into liquid He45 in the cryogenic container 46 and subjected to the fatigue testing machine 44.

Therefore, the liquid He4 in the fatigue tester 44
5 is effectively reliquefied using the He freezing device 28 and the recondenser 49, so there is almost no substantial consumption of liquefied He.

As is clear from the above explanation, according to the present invention, He is circulated in a closed cycle and the gas purifier is regenerated by releasing impurities using a heater.
There is almost no wear and tear. Additionally, by utilizing the surplus capacity of the closed cycle to heat shield the main body of the He refrigerator, running costs can be significantly reduced.

In addition, the gas purification device can perform purification and regeneration operations in parallel by appropriately switching between the two adsorption cylinders, so it exhibits stable performance even during long-term continuous operation.

Furthermore, since no valves, which are room-temperature operation parts, are provided in the cryogenic part, there are various effects such as low heat loss and good cooling performance.

[Brief explanation of the drawing]

The figure is a system diagram of a cryogenic cooling device according to the present invention. 1... Gas storage tank, 2... Supply port, 4... Isothermal compression device, 5... Gas purification device, 28... He freezing device,
40... Heat shield part, 44... Fatigue tester, 49...
Recondenser.

Claims (1)

[Claims] 1 Equipped with a He gas storage tank, a compression device, a gas purification device with a regeneration function, a surrounding heat shield, and internally equipped with a multi-stage heat exchanger and misting means such as a Joel-Thompson valve. A refrigeration system and a gas purification system are branched from the storage tank and the compression system, and one of the branches passes through the misting means to reach the load as an inflow flow, while a return flow from the load flows through the heat exchanger. The inflow stream is cooled by heat exchange with the inflow stream and returned to the storage tank, and the other branched stream passes through a part of the heat exchanger and connects with the heat shield part. 1. A cryogenic cooling device comprising: a closed cycle circuit for circulating He that returns to the storage tank after being exhausted.