JP3096969B2 - Reliquefaction equipment for liquefied gas for cooling of physics and chemistry equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a nuclear magnetic resonance apparatus (NM).
The present invention relates to an apparatus for reliquefying a liquefied gas in a physicochemical apparatus using a liquefied gas as a cooling source, such as R).

[0002]

2. Description of the Related Art In SCM-NMR, for example, in order to improve detection capability, a superconducting magnet is immersed in liquid helium in a liquid helium tank to cool the superconducting magnet, and then to a liquid helium tank (cooling refrigerant gas tank). In order to suppress heat from entering from outside, a liquid nitrogen tank (refrigerant shield gas tank) is arranged around the outer periphery of the liquid helium tank.

In the physics and chemistry equipment having the above-described structure, the heat input of liquid helium from the outside is suppressed by liquid nitrogen, whereas the heat from the outside acts on the liquid nitrogen. However, the consumption of liquid nitrogen is significantly increased. As a result, liquid nitrogen replenishment work must be performed frequently, but the operation of the physics and chemistry equipment must be stopped every time this liquid nitrogen replenishment work is performed, and the work efficiency using the physics and chemistry equipment is reduced. There was a problem.

Accordingly, the present applicant has established a refrigerant shield gas tank disposed in a physics and chemistry apparatus and a reliquefaction tank in which the inside of the tank can be cooled by a cold generation part of a cryogenic refrigerator. Communicate and connect with flexible insulated pipes arranged on a continuous downward slope toward the gas tank to eliminate replenishment of low-temperature maintaining liquefied gas (refrigerant shielding gas) or liquefied gas for cooling work (cooling refrigerant gas) Liquefied gas reliquefaction apparatus that can be made to coincide with the replenishment interval of the liquefied gas was previously proposed (Japanese Patent Laid-Open No. 8-327171).

[0005]

However, in the liquefied gas reliquefaction apparatus proposed above, the reliquefaction tank and the refrigerant shield are formed by a flexible heat insulating pipe in which the outer periphery of the cooling liquefied gas supply / discharge pipe is covered with a heat insulating outer layer pipe. In communicating with the gas tank, only the distal end of the liquefied gas supply / discharge pipe for cooling protrudes into the refrigerant liquid injection passage of the refrigerant shield gas tank, and the heat insulating outer layer pipe is located at the outer portion of the refrigerant liquid injection passage. Only the liquefied gas supply and exhaust pipe was covered.

[0007] Therefore, a temperature gradient is generated in the refrigerant liquid injection passage of the refrigerant shield gas tank due to heat input from the outside, and the re-liquefied refrigerant shield gas flowing down the cooling liquefied gas supply / discharge pipe accordingly. May be vaporized, and the re-liquefied refrigerant shield gas is not sufficiently returned to the refrigerant shield gas tank. The present invention has been made in view of such a point, and when the refrigerant shield gas is reliquefied using a cryogenic refrigerator and returned to the cooling liquefied gas tank of the scientific equipment, the recirculated refrigerant gas is returned. An object of the present invention is to provide a liquefied gas reliquefaction apparatus capable of reliably returning a reliquefied cooling liquefied gas as a liquid to a liquefied cooling gas tank by suppressing the vaporization of the liquefied liquefied cooling gas. .

[0008]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a method for cooling a heat-insulating outer layer tube constituting a flexible heat-insulating tube for connecting a reliquefaction tank and a liquefied gas tank for cooling. The end on the side of the liquefied gas tank for cooling is formed to have a smaller diameter than the outer diameter of the middle part, and is formed so as to protrude into the refrigerant liquid injection passage of the liquefied gas tank for cooling, and constitutes a flexible heat insulating tube. The cooling liquefied gas supply / discharge pipe has an end on the cooling liquefied gas tank side located at the lower end portion of the refrigerant liquid injection passage of the cooling liquefied gas tank.

[0009]

According to the present invention, the end of the heat insulating outer layer tube constituting the flexible heat insulating tube on the side of the cooling liquefied gas tank is formed to have a smaller diameter than the outer diameter of the intermediate portion. Since the cooling liquefied gas is formed so as to be sufficiently inserted into the refrigerant liquid injection passage of the tank, the cooling liquefied gas returned inside the flexible insulation is affected by the temperature gradient in the refrigerant liquid injection passage in the cooling liquefied gas tank. Therefore, the evaporation of the reliquefied cooling liquefied gas can be suppressed. Further, when the outer surface of the portion of the heat-insulating pipe that enters the refrigerant liquid injection passage is electrically insulated as described in claim 2, the electric noise transmitted through the flexible heat-insulating pipe is transmitted to the physical and chemical equipment. Can be suppressed.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention, and FIG. 1 is a schematic structural diagram in the case where liquid nitrogen from SCM-NMR is reliquefied. This reliquefaction apparatus includes an SCM-NMR (1) serving as a source of vaporized gas, a reliquefaction tank (2),
A flexible heat insulating pipe for communicating a storage tank (3) for liquid nitrogen, which is a refrigerant shielding gas of CM-NMR (1), and a reliquefaction tank (2).
(4) and a cryogenic refrigerator (6) having a low-temperature generating section (5) inserted into the reliquefaction tank (2).

[0011] The SCM-NMR (1) includes a storage tank (7) for liquid helium as a cooling refrigerant and a storage tank (3) for liquid nitrogen as a refrigerant shielding gas in a casing formed in a vacuum insulation structure. The superconducting magnet (9) is immersed in the liquid helium in the liquid helium storage tank (7). And a liquid nitrogen storage tank (3) arranged so as to surround the liquid helium storage tank (7).
Functions as a heat shield medium that suppresses transfer of heat from the outside to the liquid helium storage tank (7).

The reliquefaction tank (2) has a vacuum insulation structure, and is supported on a fixed structure such as a column (10) via a vibration isolator (11) in a room where the SCM-NMR is arranged. It is. A cooling liquefied gas supply / discharge pipe (13) is drawn out of the casing in a state obliquely downward from a location above the lower end of the inner wall (12) of the reliquefaction tank (2) by a certain height. For this reason, a reliquefied gas storage part (14) is formed at the bottom in the reliquefaction tank (2), and the cooling liquefied gas supply / discharge pipe (13) serves as an outlet pipe for the refrigerant shield gas. The upper opening of the reliquefaction tank (2) is closed by a flange (15), and the cryogenic refrigerator (6) fixedly supported on the column (10) while penetrating the flange (15). Cold head (16) is arranged. A pressure outlet pipe (17) is led out of the flange (15), and a relief valve (18) and a pressure gauge (19) are mounted on the pressure outlet pipe (17).

The cryogenic refrigerator (6) comprises a compressor unit (20) and the aforementioned cold head (16).
The cold generating part (5) formed at the lower end of (16) is reliquefied (2)
Into the interior. And the compressor unit (20)
The cooler (2) is connected to the high pressure gas supply passage (22) connecting the discharge port of the compressor (21) and the inflow port of the cold head (16).
3), an oil separator (24) and an oil adsorber (25) are arranged in series, and a high-pressure gas supply path (22) between the oil separator (24) and the oil adsorber (25) is connected to a cold head ( A pressure-retaining valve (27) is connected to the low-pressure gas return path (26) connecting the return port of (16) and the suction port of the compressor (21).
And is connected via a.

The flexible heat insulating pipe (4) is integrally extended from the reliquefaction tank (2), and is a shield gas supply / discharge made of a pipe made of a non-magnetic material such as an annealed copper pipe or a thin stainless steel pipe. Tube (1
The outer periphery of 3) is covered with an outer layer pipe (29) formed of a smoothed copper pipe or a metal flexible pipe, etc., and a shielding gas supply / discharge pipe (28) and an outer layer pipe (29)
Is connected to the vacuum space of the reliquefaction tank (2) to form a vacuum adiabatic space.
It is arranged in a state of a continuous downward slope toward CM-NMR (1). The lower end portion of the shield gas supply / discharge pipe (28) is inserted into the inside from the upper opening of the liquid nitrogen injection passage (30) formed so as to communicate with the liquid nitrogen storage tank (3) of the SCM-NMR (1). The shield gas supply and exhaust pipe (2
8) The lower end of the liquid nitrogen injection passage (30) and the liquid nitrogen storage tank
It is located at the communication port with (3). The liquefied gas deriving system composed of the flexible heat insulating pipe (4) and the liquefied gas supply / discharge pipe (13) for cooling the reliquefaction tank (2) has its axis inclined at 15 degrees with respect to the horizontal line. It is arranged in an angled state.

Also, as shown in FIG.
The outer layer pipe (29) of (4) has an outer diameter formed at the lower end portion of a small diameter, and the small diameter portion is formed slightly smaller than the inner diameter of the liquid nitrogen injection passage (30). The part can be inserted into the liquid nitrogen injection passage (30). On the other hand, the outer diameter of the flexible heat insulating pipe (4) in the outer layer pipe (29) is formed to be equal to the outer diameter of the neck part constituting the liquid nitrogen injection passage (30). In a state in which the liquid nitrogen storage tank (3) is connected to the liquid nitrogen storage tank (3), the neck portion forming the liquid nitrogen injection passage (30) and the outer surface of the outer tube are connected by the heat insulating joint (31).

Further, an electric insulating coating is formed on the outer peripheral surface of the small diameter portion of the outer tube (29), and the electric insulating treatment is performed. If the outer peripheral surface of the small-diameter portion of the outer tube (29) is subjected to electrical insulation treatment in this way, the operation of the compressor (21) of the cryogenic refrigerator (6) and the rotary valve drive motor of the cold head (16) can be performed. Can be suppressed from being transmitted to the physics and chemistry equipment such as SCM-NMR (1) and affecting measurement accuracy.

FIGS. 3 and 4 show a modification of the arrangement of the reliquefaction tank (2). FIG. 2 shows the reliquefaction tank (2) in which the axis of the inner tank of the reliquefaction tank (2) is perpendicular to the vertical line. The cooling liquefied gas supply / discharge pipe (13) extends continuously from the center of the inclined inner tank bottom wall (32) to the horizontal plane. Thus, by arranging the reliquefaction tank (2) in an inclined manner, the height from the floor surface to the upper end of the reliquefaction tank (2) can be suppressed, and the reliquefaction tank (2) can be used even in a place where the ceiling height is low. It becomes possible.

In the embodiment shown in FIG. 3, the strut (10)
A buffer tank (33) is arranged in the inside, and a gas return pipe (34) from the cold head (16) of the cryogenic refrigerator (6) to the compressor unit (20) is connected. Thus the compressor unit
When the buffer tank (33) is interposed in the low pressure gas return path to (20), the efficiency as the cryogenic refrigerator (6) is improved.

FIG. 4 shows an arrangement in which a cold head (16) of a cryogenic refrigerator (6) is disposed at the bottom of a reliquefaction tank (2), and a liquefied gas supply / discharge pipe (13) for cooling is provided inside. It is open at a certain height above the lower end of the tank side wall.

In each of the above embodiments, the flexible heat insulating pipe (4)
The liquefied gas outlet system constituted by the liquefied gas supply / discharge pipe (13) for cooling the reliquefaction tank (2) is arranged at an inclination angle of 15 degrees with respect to the horizontal line. Can be set in the range of degrees. If the inclination angle of the liquefied gas derivation system is smaller than 15 degrees, the flow speed of the liquid flowing in the liquefied gas derivation system becomes slow, and the contact time with the gas moving upward in the liquefied gas derivation system increases. Since the amount of vaporization also increases, smooth return of the liquid cannot be expected, and if the inclination angle is set to a steep angle larger than 60 degrees, a gas lock phenomenon occurs in the liquefied gas discharge system and the liquid Smooth exchange between gas and gas cannot be expected.

In the reliquefaction apparatus having the above configuration, the SC
The nitrogen gas vaporized in the liquid nitrogen storage tank (3) in the M-NMR (1) is led out to the reliquefaction tank (2) through the flexible heat insulating pipe (4) which is inclined and piped, and this reliquefaction is performed. The re-liquefied gas storage part (14) formed in the bottom of the re-liquefaction tank (2) by being re-liquefied by cold from the cold generation part (5) of the cryogenic refrigerator (6) in the tank (2)
The flexible insulating pipe in which the reliquefied gas overflowing from the reliquefied gas storage part (14)
It flows down along the bottom wall of (4) and is returned to the liquid nitrogen storage tank (3) in SCM-NMR (1). As a result, the vaporization and dissipation of liquid nitrogen in SCM-NMR (1) is suppressed.

In each of the above embodiments, SCM-NMR has been described as a physical and chemical instrument using a liquefied gas as a cooling refrigerant. However, other types of NMR and electron microscopes are used to cool the liquefied gas at a low temperature. Can be used for reliquefaction of the refrigerant liquefied gas of the equipment. Further, it can be used for reliquefaction of a liquefied gas for cooling that directly cools an object to be cooled such as a detection device.

[0023]

According to the present invention, the end portion of the heat insulating outer layer tube constituting the flexible heat insulating tube on the side of the liquefied gas tank for cooling is formed to have a smaller diameter than the outer diameter of the intermediate portion. Since it is formed so as to protrude into the refrigerant liquid injection passage of the liquefied gas tank, the cooling liquefied gas which is reliquefied and returned to the cooling liquefied gas tank has a temperature in the refrigerant liquid injection passage in the liquefied gas tank for cooling. The influence of the gradient can be suppressed, and the cooling in the physics and chemistry equipment can be stably performed.

Further, when the outer surface of the portion of the heat-insulating pipe protruding into the coolant liquid injection passage is electrically insulated as described in claim 2, electric noise transmitted through the flexible heat-insulating pipe is transmitted to the physics and chemical equipment. Conduction can be suppressed, and the measurement accuracy as a physicochemical instrument can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram in a case where liquid nitrogen from SCM-NMR is reliquefied.

FIG. 2 is an enlarged sectional view of a main part.

FIG. 3 is an enlarged sectional view showing a modification of the arrangement of the reliquefaction tank.

FIG. 4 is an enlarged cross-sectional view showing a modified example in which the arrangement of the reliquefaction tank is different.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Physicochemical equipment, 2 ... Reliquefaction tank, 3 ... Liquefied gas tank for cooling, 4 ... Flexible insulation tube, 5 ... Cold generation part of cryogenic refrigerator, 6 ... Cryogenic refrigerator, 10 ... Strut, 13 ... liquefied gas supply / discharge pipe for cooling, 29 ... outer pipe of flexible heat insulating pipe, 30 ... coolant liquid injection passage of liquefied gas tank for cooling, 32 ... bottom wall of reliquefaction tank, 33 ... buffer tank, 34 ... cryogenic Gas return pipe of refrigerator (6).

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Bungo Kondo 1095 Katsube-cho, Moriyama-shi, Shiga Prefecture Iwatani Gas Co., Ltd. References JP-A-8-327171 (JP, A) JP-A-60-73264 (JP, A) JP-A-63-140275 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) F25B 9/00 F25D 3/10

Claims (5)

(57) [Claims] 1. A cooling liquefied gas tank (3) of a physics and chemistry equipment (1) using liquefied gas as a cooling refrigerant, and a cryogenic refrigerator (6) in a cryogenic refrigerator (6). The reliquefaction tank (2), which is configured to be cooled, is connected to a refrigerating gas tank (3) by a flexible insulated pipe (4) arranged continuously downward toward the liquefied gas tank (3). In the liquefaction apparatus, the end of the outer layer pipe (29) constituting the flexible heat insulating pipe (4) on the side of the liquefied gas tank for cooling (3) is formed to have a smaller diameter than the outer diameter of the middle part. Liquid injection passage for the liquefied gas tank for cooling (3)
(30) and a flexible insulation tube
The end of the cooling liquefied gas supply / discharge pipe (13), which constitutes (4), on the cooling liquefied gas tank (3) side is connected to the refrigerant liquid injection passage (30) of the cooling liquefied gas tank (3). A reliquefaction apparatus for a liquefied gas for cooling physics and chemistry equipment, wherein the apparatus is configured to be located at a lower end portion. 2. A surface of a portion of the outer layer pipe (29) of the flexible heat insulating pipe (4) that enters the refrigerant liquid injection passage (30) of the liquefied gas tank for cooling (3) is electrically insulated. 4. The reliquefaction apparatus for a liquefied gas for cooling physics and chemistry equipment according to claim 1. 3. The reliquefaction tank (2) is supported by a column (10), a buffer tank (33) is formed in the column (10), and the gas of the cryogenic refrigerator (6) is stored in the buffer tank (33). The reliquefaction apparatus for a liquefied gas for cooling physics and chemistry equipment according to claim 1 or 2, wherein a return pipe (34) is connected. 4. A liquefied gas supply / discharge pipe (13) for cooling of a flexible heat insulating pipe (4) is continuously extended from a bottom wall (32) of the reliquefaction tank (2).
Is disposed so as to be inclined with respect to a horizontal plane, and the discharge portion of the liquefied gas supply / discharge pipe (13) for cooling is configured to be located at a fixed height from the lower corner portion. The reliquefaction apparatus for a liquefied gas for cooling physics and chemistry equipment according to claim 3. 5. A reliquefaction apparatus for a liquefied gas for cooling physics and chemistry equipment according to claim 1, wherein a cold generating part (5) is arranged from the bottom at the bottom of the reliquefaction tank (2).