JPH079346B2 - Helium liquefier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a device for liquefying helium, which is precooled by a hydrogen liquefying device using a hydrogen storage alloy and which does not use a rotary machine and can be used for a long time. It is designed to be able to drive for hours.

[Prior Art] Liquid helium obtained by liquefying helium, which has the lowest boiling point among gases, is indispensable for research on superconductivity and superfluidity of substances, and is being applied to various new electronic devices.

To liquefy such helium, for example, as shown in FIG. 2, a liquid helium cycle A and a liquid nitrogen cycle B for precooling are attached, and the helium gas compressed by the compressor 1 is precooled. After being sent to the heat exchanger 2 for cooling and precooled with liquefied nitrogen from the liquefied nitrogen cycle B, a part of the helium gas that goes to the throttle valve 3 is put into the expansion turbine 4 for reversible expansion, and the helium which has become low temperature is throttled. 3 to separator 5
Through helium that returns to compressor 1 via
This return gas and helium to the throttle valve 3 are used as the first and second
While allowing heat to be exchanged with the heat exchangers 6 and 7, the separator 5
I am trying to get liquid helium.

The liquefied nitrogen cycle B used in this case is, for example, 3
It is composed of the compressors 8, 9, 10 of the stage, the heat exchanger 11, the throttle valve 12, etc., and the liquid nitrogen is obtained in the separator 13 by utilizing the expansion of the throttle.

[Problems to be Solved by the Invention] In such a helium liquefier, compressors 8, 9, 10 driven by a motor or the like are installed in a liquid nitrogen cycle B additionally provided for precooling compressed helium gas. Has been done,
Lubricating oil is used to lubricate rotating parts. When air or the like is mixed in the lubricating oil, there is a problem that the heat exchanger 11 or the throttle valve 12 freezes and adheres, and a very small amount of the lubricating oil is circulated through the adsorber, There is a problem that this adheres to the heat transfer surface of the heat exchanger 11 and the heat exchanger efficiency decreases.

These problems of air mixing and circulation of lubricating oil are gradually accumulated because the lubricating oil needs to be replenished with the operation of the compressor, and the influence thereof becomes large, resulting in a decrease in heat transfer efficiency.

So, in the past, if you operate for about 2000 hours at the longest,
Since the operation is stopped and the heat exchanger 11 and the adsorber are cleaned, there is a problem that continuous operation for a long time cannot be performed.

In order to improve the efficiency of the liquid helium cycle A,
It is effective to lower the precooling temperature as much as possible, and there is a need for a simple device that can further lower the temperature.

The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to reduce the precooling temperature without using a rotating machine that requires lubricating oil, and to perform a long-term continuous operation of helium. It is intended to provide a liquefaction device.

[Means for Solving the Problems] In order to solve the above problems, the helium liquefying device of the present invention liquefies helium by precooling helium gas and then combining reversible expansion by an expander and throttle expansion by a throttle valve. In the liquefaction device, a helium gas precooling heat exchanger is provided on the inlet side of the helium gas compressor, and a hydrogen liquefaction cycle in which a hydrogen liquefaction cycle for sending precooling liquid hydrogen to this helium gas precooling heat exchanger is entered by the hydrogen storage alloy. Heating and cooling can be switched to release and store hydrogen gas, two heat exchangers, a heat exchanger that cools high-pressure hydrogen gas discharged from the heated reaction vessel, and the cooled hydrogen gas can be reversible. It is composed of an expander and a throttle valve that perform expansion and throttle expansion in combination, and a separator that separates liquid hydrogen from expanded hydrogen. It is characterized in that liquid heat for precooling is connected to a heat exchanger for precooling helium gas so that it can be supplied.

[Operation] In a hydrogen liquefaction cycle using such a hydrogen storage alloy, two reaction vessels capable of releasing / storing hydrogen gas by inserting a hydrogen storage alloy and switching between heating and cooling, and releasing from the heated reaction vessel The heat exchanger for cooling the high-pressure hydrogen gas, the expander and throttle valve for performing the reversible expansion and the restriction expansion of the cooled hydrogen gas, and the separator for separating the liquid hydrogen from the expanded hydrogen. Since it is configured to pre-cool helium and does not use a rotating machine such as a compressor, it does not require lubricating oil, and problems such as clogging and pollution due to air in lubricating oil and circulation of lubricating oil itself are eliminated. It eliminates the need for continuous operation for a long time.

In addition, since liquid hydrogen whose temperature is lower than that of liquid nitrogen is used for pre-cooling, it is possible to more efficiently liquefy helium, and to cool helium at the inlet side of the compressor of the liquid helium cycle, such as a turbo compressor. It also allows the use of low temperature compressors.

[Embodiment] An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram according to an embodiment of a helium liquefying apparatus of the present invention.

This helium liquefaction device 20 is a liquid helium cycle A
And a liquid hydrogen cycle C.

Liquid helium cycle A consists of three precooling heat exchangers 21,22,
23 is provided for precooling with the liquid hydrogen from the liquid hydrogen cycle C, and after the helium gas cooled in the first precooling heat exchanger 21 is sent to the low pressure compressor 24 and compressed, It is cooled in the second precooling heat exchanger 22 as an intercooler, further pressurized by the high-pressure compressor 25, and cooled in the third precooling heat exchanger 23.

The low-temperature high-pressure helium cooled in this way is sent to the throttle valve 26, and part of the helium is expanded along the expansion turbine 27.
The helium, which has been cooled and reversibly expanded due to its low temperature, is joined with the helium from the throttle valve 26, and the return gas and the helium to the throttle valve 26 are heat-exchanged by the heat exchanger 28, and separated. Liquid helium is obtained in vessel 29.

On the other hand, the liquid hydrogen cycle C used for precooling the helium gas is for compressing the hydrogen gas using a hydrogen storage alloy.

In this liquid hydrogen cycle C, reaction vessels 30 and 31 in which two hydrogen storage alloys are placed are provided, and one of them is heated by a heating source such as steam to release the adsorbed hydrogen to generate high-pressure hydrogen. The other side is cooled with cooling water such as water and adsorbs hydrogen.

In this way, the two reaction vessels 30 and 31 function as a hydrogen compressor, and after the reaction is saturated in each of the reaction vessels 30 and 31, they are operated by the two three-way valves 32 and 33. It can be used continuously by switching between cooling and heating.

As the hydrogen storage alloy is placed in these reaction vessels 30 and 31, for example when heated to 100 ° C., is discharged high-pressure hydrogen 40~50kg / cm ^2, room temperature and atmospheric pressure (20 ℃, 1kg / cm ² or so) degrees It is used that has the property of absorbing hydrogen when cooled at.

For example, the two three-way valves 32 and 33 are closed in black in the figure, the reaction container 30 is on the heating side, and the reaction container 31 is
On the cooling side, the high-pressure hydrogen released from the reaction vessel 30 is transferred from the three-way valve 32 to the first, second and third heat exchangers 34, 35, 36.
On the way to the throttle valve 37 while being cooled by, part of the hydrogen is sent to the expansion turbine 38 and reversibly expanded, and the low temperature hydrogen is merged with hydrogen returning from the throttle valve 37 to the separator 39 to the reaction vessel 31. At the same time, this return gas and hydrogen to the throttle valve 37 are heat-exchanged in the first, second and third heat exchangers 34, 35, 36,
Liquid hydrogen is obtained in the separator 39 together with low-temperature hydrogen gas.

The low-temperature fluid of hydrogen thus obtained is sent to the first, second and third heat exchangers 21, 22, 23 for precooling of the liquid helium cycle A to precool helium.

Then, the precooled hydrogen is sent to the reaction vessel 31 through the three-way valve 33 and is stored in the hydrogen storage alloy.

In this way, hydrogen is released and occluded in the two reaction vessels 30 and 31, and after the respective reactions are saturated, two three-way valves are set so that the heating side is the cooling side and the cooling side is the heating side.
Continuous operation is performed by switching between 32 and 33 and closing the shaded area in the figure.

According to such a helium liquefying apparatus 20, since the liquid hydrogen cycle B for precooling uses the hydrogen storage alloy, there is no rotating machine part and no lubricating oil is used. The second and third heat exchangers 34, 35, 36 do not adhere to and deposit on the heat transfer portions, and the heat transfer performance does not deteriorate even after long-term operation.

Further, since the liquid helium cycle A is pre-cooled at the liquid hydrogen temperature, it can be made lower than in the case of using liquid nitrogen, liquefying helium is facilitated, and helium before being sucked into the low pressure compressor 24 is used. Since it is cooled, helium with high density can be compressed efficiently.

In addition, high pressure is possible, a low temperature compressor can be used, a turbo compressor can be used, the device can be downsized, and it can be easily housed in a drum, etc. Prevention is also easy.

In the above embodiment, the liquid helium cycle has two stages of compressors. However, the number of stages is not limited to this, and more stages may be used, or a reciprocating type may have one stage.

[Effects of the Invention] According to the helium liquefaction device of the present invention as specifically described above with reference to the embodiment, the hydrogen storage alloy is used in the heat exchanger for precooling the helium gas compressed by the compressor. Since liquid hydrogen obtained by occluding and releasing hydrogen is supplied, a rotating machine such as a compressor is not used.Therefore, lubricating oil is not required, and clogging due to circulation of air in the lubricating oil or the lubricating oil itself The problem of pollution was eliminated and continuous operation for a long time became possible.

Also, since liquid hydrogen, which has a lower temperature than conventional liquid nitrogen, is used for pre-cooling, helium can be liquefied more efficiently, and if helium is cooled at the inlet side of the compressor in a liquid helium cycle, a turbo A low-temperature compressor such as a compressor can be used, and it is easy to make the device compact, and it is easy to put it in a drum or the like to shut off heat from the outside or to shut off noise.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram according to an embodiment of a helium liquefying device of the present invention, and FIG. 2 is a schematic configuration diagram of a conventional device. 20: helium liquefier, 21,22,23: heat exchangers for first, second and third pre-cooling, 24,25: low and high pressure compressors, 26: throttle valve, 27: expansion turbine, 28: heat Exchanger, 29: Separator, 30,3
1: reaction vessel, 32, 33: three-way valve, 34, 35, 36: first, second and third heat exchangers, 37: throttle valve, 38: expansion turbine, 39: separator.

Claims (1)

[Claims] 1. A liquefying device for liquefying helium by precooling helium gas, and then combining reversible expansion by an expander and expansion by a throttle valve, wherein a heat exchanger for precooling helium gas is replaced by a compressor for helium gas. A hydrogen liquefaction cycle, which is installed on the inlet side and sends liquid hydrogen for precooling to the heat exchanger for precooling helium gas, is a hydrogen liquefaction cycle in which a hydrogen storage alloy is inserted and heating / cooling can be switched to release and store hydrogen gas. A container, a heat exchanger for cooling the high-pressure hydrogen gas discharged from the heated reaction container, an expander and a throttle valve for combining the cooled hydrogen gas with reversible expansion and throttle expansion, It is composed of a separator for separating liquid hydrogen from hydrogen, and the separator for this hydrogen liquefaction cycle is connected to the heat exchanger for precooling the helium gas so that liquid hydrogen for precooling can be supplied. Liquefier helium characterized by.