GB2251930A - Device for preventing evaporation of liquefied gas in a liquefied gas reservoir - Google Patents

Device for preventing evaporation of liquefied gas in a liquefied gas reservoir Download PDF

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Publication number
GB2251930A
GB2251930A GB9101154A GB9101154A GB2251930A GB 2251930 A GB2251930 A GB 2251930A GB 9101154 A GB9101154 A GB 9101154A GB 9101154 A GB9101154 A GB 9101154A GB 2251930 A GB2251930 A GB 2251930A
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United Kingdom
Prior art keywords
liquefied gas
gas reservoir
reservoir
cold head
refrigerator
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9101154A
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GB2251930B (en
GB9101154D0 (en
Inventor
Masayoshi Yanai
Etsuji Kawaguchi
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Iwatani Corp
Original Assignee
Iwatani Corp
Iwatani Sangyo KK
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Publication date
Application filed by Iwatani Corp, Iwatani Sangyo KK filed Critical Iwatani Corp
Priority to GB9101154A priority Critical patent/GB2251930B/en
Priority to DE19914101786 priority patent/DE4101786A1/en
Publication of GB9101154D0 publication Critical patent/GB9101154D0/en
Publication of GB2251930A publication Critical patent/GB2251930A/en
Application granted granted Critical
Publication of GB2251930B publication Critical patent/GB2251930B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0257—Construction and layout of liquefaction equipments, e.g. valves, machines
    • F25J1/0275—Construction and layout of liquefaction equipments, e.g. valves, machines adapted for special use of the liquefaction unit, e.g. portable or transportable devices
    • F25J1/0276—Laboratory or other miniature devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C3/00—Vessels not under pressure
    • F17C3/02—Vessels not under pressure with provision for thermal insulation
    • F17C3/08—Vessels not under pressure with provision for thermal insulation by vacuum spaces, e.g. Dewar flask
    • F17C3/085—Cryostats
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D19/00—Arrangement or mounting of refrigeration units with respect to devices or objects to be refrigerated, e.g. infrared detectors
    • F25D19/006—Thermal coupling structure or interface
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2203/00—Vessel construction, in particular walls or details thereof
    • F17C2203/06—Materials for walls or layers thereof; Properties or structures of walls or their materials
    • F17C2203/0602—Wall structures; Special features thereof
    • F17C2203/0612—Wall structures
    • F17C2203/0626—Multiple walls
    • F17C2203/0629—Two walls
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2221/00—Handled fluid, in particular type of fluid
    • F17C2221/01—Pure fluids
    • F17C2221/014—Nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
    • F17C2223/01—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the phase
    • F17C2223/0146—Two-phase
    • F17C2223/0153—Liquefied gas, e.g. LPG, GPL
    • F17C2223/0161—Liquefied gas, e.g. LPG, GPL cryogenic, e.g. LNG, GNL, PLNG
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
    • F17C2223/03—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the pressure level
    • F17C2223/033—Small pressure, e.g. for liquefied gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
    • F17C2227/03—Heat exchange with the fluid
    • F17C2227/0337—Heat exchange with the fluid by cooling
    • F17C2227/0341—Heat exchange with the fluid by cooling using another fluid
    • F17C2227/0353—Heat exchange with the fluid by cooling using another fluid using cryocooler
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/04—Indicating or measuring of parameters as input values
    • F17C2250/0404—Parameters indicated or measured
    • F17C2250/0408—Level of content in the vessel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/04—Indicating or measuring of parameters as input values
    • F17C2250/0404—Parameters indicated or measured
    • F17C2250/0439—Temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2270/00—Applications
    • F17C2270/05—Applications for industrial use
    • F17C2270/0509—"Dewar" vessels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2270/00—Applications
    • F17C2270/05—Applications for industrial use
    • F17C2270/0518—Semiconductors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/42—Modularity, pre-fabrication of modules, assembling and erection, horizontal layout, i.e. plot plan, and vertical arrangement of parts of the cryogenic unit, e.g. of the cold box

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Health & Medical Sciences (AREA)
  • Clinical Laboratory Science (AREA)
  • Measurement Of Radiation (AREA)
  • Details Of Measuring And Other Instruments (AREA)

Abstract

A device for preventing evaporation of liquefied gas in a liquefied gas reservoir used to cool an EDS detector of an electron microscope or the like, wherein a cold head 12 of a cryogenic refrigerator 11 is disposed so as to fit an opening 10 of the top of the liquefied gas reservoir 4 and moreover a temperature measuring instrument 17 or a level gauge is disposed within the liquefied gas reservoir 4 so that the cryogenic refrigerator 11 is automatically operated depending on the temperature within the liquefied gas reservoir 4 or on change in the liquid level of liquefied gas, whereby vaporized gas is condensed and reliquefied, thus suppressing wasteful dissipation of vaporized gas. <IMAGE>

Description

k 1
SPECIFICATION
2251 3C, Title of the Invention:
Device for Preventing Evaporation of Liquefied Gas in a Liquefied Gas Reservoir 1 BACKGROUND OF THE INVENTION Field of the Invention
The present invention relates to devices for preventing evaporation of liquefied gas in a low-temperature generator used for, with liquefied gas, cooling an EDS detector (Energy Dispersive Spectrometer -type X-ray detector) that allows electron microscopes to have the element analysis function.
2. Description of the Prior Art
Conventional electron microscopes have such an arrangement that the EDS detector is cooled with liquid nitrogen so as to enhance their measurement accuracy. In such an electron microscope, conventionally, there is'provided a cold finger that is coupled with and drawn from the bottom wall of a reservoir in which liquid nitrogen is stored and an EDS detector is mounted to the cold finger, thereby allowing the EDS detector to be held in a cryogenically low temperature state with the use of liquid nitrogen.
The EDS detector used in such a type of apparatus is required to keep its cooling temperature within a certain range once the detector has been cooled. The liquid nitrogen used to cool the EDS detector, however, is subject to some dissipation out of its reservoir due to evaporation. This compels an operator to frequently refill the liquefied gas reservoir with liquid nitrogen in order to make up for dissipated liquid nitrogen.
Disadvantageously, since an electron microscope-, incorporating an EDS detector restricts the floor height at which the liquefied gas reservoir for cooling the EDS 2 t detector is disposed, relative to the irradiation axis thereof, the liquefied gas supply port opening at the upper portion of the reservoir has a height from the floor, for example, as high as 1.5 m. As a result, it would be laborious work for the operator to rekill the liquid nitrogen reservoir with liquid nitrogen using a supply vessel such as a Dewar vessel.
The present invention has been accomplished in view of the foregoing problems and therefore it is the primary object of the invention to provide devices for preventing evaporation of liquefied gas in a liquefied gas reservoir which can dispense with the resupply of liquefied gas over a long time period.
Summary of the Invention
To achieve the above-mentioned object, the. present invention provides a device for preventing evaporation of liquefied gas characterized in that, in an electron microscope in which a cold finger is coupled with and drawn from a liquefied gas reservoir and an EDS detector is secured thereto, the arrangement is such that a cold head of a cryogenic refrigerator is disposed so as to fit an opening at the top of the liquefied gas reservoir and is braced to a frame with a linear guide mechanism interposed therebetween, the liquefied gas reservoir is braced to the cold head of the cryogenic refrigerator with vibration preventive means interposed therebetween, and the cold end of the cold head is plunged into the liquefied gas reservoir from the opening at the top thereof so as to allow the temperature within the liquefied gas reservoir to be detected by a temperature measuring instrument, whereby the cryogenic refrigerator is controlled for its automatic operation according to the temperature detected by the temperature measuring instrument, whereas the invention provides another device for preventing evaporation of liquefied gas further characterized in that, 3 in addition to the above arrangement, a lead-in passageway for refrigerant gas is disposed so as to be communicated with the opening at the top of the liquefied gas reservoir, the gas lead-in passageway having a gas supply control valve interposed therein, wherein the gab supply control valve is controlled for opening and closing and moreover the cryogenic refrigerator is controlled for its automatic operation according to the lower-limit liquid level detection actuation of a level gauge which is adapted to detect the liquefiedgas liquid level within the liquefied gas reservoir.
Since a device for preventing evaporation of liquefied gas according to the present invention has such an arrangement that, in a measuring instrument in which a cold finger is coupled with and drawn from a liquefied gas reservoir and a semiconductor sensor is secured thereto, a cold head of a cryogenic refrigerator is disposed so as to fit an opening at the top of the liquefied gas reservoir and is braced to a frame with a linear guide mechanism interposed therebetween, the liquefied gas reservoir is braced to the cold head of the cryogenic refrigerator with vibration preventive means interposed therebetween, and the cold end of the cold head is plunged into the liquefied gas reservoir from the opening at the top thereof so as to allow the temperature within the liquefied gas reservoir to be detected by a temperature measuring. instrument, whereby the cryogenic refrigerator is controlled for its automatic -operation according to the temperature detected by the temperature measuring instrument, vaporized gas within the liquefied gas is cooled and condensed by the cryogenic refrigerator, thus being reliquefied. Accordingly, vaporized gas is no longer dissipated wastefully so that the cycle of refilling the liquefied gas can be prolonged, the work load of refilling the liquefied gas reservoir with the liquefied gas can be lightened, and that the EDS detector can be cooled continuously over a long period and therefore maintained at reservoir 4 a constant extremely low temperature. In consequence, it is allowable to continue the measurement with the electron microscope for a long time with high accuracy.
On the other hand, since another device for preventing evaporation of liquefied gas acdording to the invention has such an arrangement that a lead-in passageway for refrigerant gas is disposed so as to be communicated with an opening at the top of a liquefied gas reservoir, the gas lead-in passageway having a gas supply control valve interposed therein, a cold head of a cryogenic refrigerator is disposed so as to fit an opening at the top of the liquefied gas reservoir and is braced- to a frame with a linear guide mechanism interposed therebetween, the liquefied gas reservoir is braced to the cold head of the cryogenic refrigerator with vibration preventive means interposed therebetween, and the cold end of the cold head is plunged into the liquefied gas reservoir from the opening at the top thereof so as to allow the liquefied-gas liquid level within the liquefied gas reservoir to be detected by a level gauge, wherein the gas supply control valve is controlled for opening and closing and moreover the cryogenic refrigerator is controlled for its automatic operation according to the the lower-limit liquid level detection actuation of the level gauge, when the liquid level in the liquefied gas reservoir is lowered below a certain level, refrigerant gas of vapor state is automatically introduced into the lique-fied gas reservoir and at the same time the cryogenic refrigerator is actuated to condense and reliquefy the introduced refrigerant gas, thus enabling the liquefied gas within the liquefied gas reservoir to be held constantly within a certain range. Accordingly, vaporized gas is no longer dissipated wastefully so that the cycle of refilling liquefied gas reservoir with liquefied gas can be prolonged thereby to lighten the work load of resupplying liquefied gas, the work of refilling liquefied gas can be automated to lighten the load imposed on an operator and moreover the EDS detector can be cooled continuously over a long period, allowing the semiconductor to be held at a constant extremely low temperature, with the result that the electron microscope allows the measurement to be continued for a long time with high accuracy.
Still more, since the cryogenic refrigerator is operationcontrolled by detecting the temperature or liquid level within the liquefied gas ' reservoir, the cryogenic refrigerator can be operated without being involved in wasteful operation.
Further, since the cold head of the cryogenic refrigerator is braced with vibration prevented for the liquefied gas reservoir, even being used'as the cryogenic refrigerator is, the vibration due to the operation of the cryogenic refrigerator is prevented from being transmitted to the liquefied gas. reservoir, thus eliminating various adverse effects that would occur from the vibration of the liquefiedgas liquid level.
Brief Description of the Drawings
Fig. 1 is an enlarged sectional view of the main portion of the present invention; Fig. 2 is a side view of a low-temperature generator; and Fig. 3 is a conceptual view of the same.
Description of the Preferred Embodiments of the Invention
A low-temperature generator 1 is composed of a liquefied gas reservoir 4 which has a cold finger 7 coupled with and drawn from its bottom wall 5 supporting a semiconductor sensor 6 in an instrument such as a scanning type electron microscope, and a cryogenic refrigerator 11 disposed on the upper side of the liquefied gas reservoir 4. The liquefied gas reservoir 4 is formed of a heat-insulating vessel and has refrigerant liquefied gas stored therein such as liquid nitrogen.
6 The cryogenic refrigerator 11 is composed of a cold head 12 and a compressor unit 13, the cold head 12 being braced to the upper end of a frame 3 erected from the floor 2 so as to fit an opening 10 at the top of the liquefied gas reservoir 4, the compressor unit 13 being braced to the floor 2 in a vibration-proof condition. The compressor unit 13 and the cold head 12 are communicated with each other with the aid of two flexible tubes 14, wherein gas refrigerant such as helium compressed by the compr essor unit 13 is adiabatically expanded within the cold head 12 so that a cryogenic temperature can be obtained.
A cold end 15 of the cold head 12 is plunged into the above-mentioned liquefied gas reservoir 4 from the opening 10 at the top thereof, so that refrigerant liquefied gas vaporized within the liquefied gas reservoir 4 is condensed and reliquefied through the coldne.ss that takes place at the cold end 15.
Furthermore, between the cold head 12 and the liquefied gas reservoir 4 there are disposed bellows 16 as vibration preventive support means so as to prevent vibration accompanying the operation of the cryogenic refrigerator 11 from being transmitted to the liquefied gas reservoir 4. These bellows are of double bellows with an airtight chamber formed between inner bellows 16a and outer bellows 16b, the airtight chamber being held at one atmospheric pressure. When the pressure within the liquefied gas reservoir 4 becomes negative due to the operation of the cryogenic refrigerator 11, although the bellows 16 attempt to shrink, the intermediate sealed chamber has one atmospheric pressure charged therein and therefore the atmospheric pressure thereof makes resistance against the shrinking actuation, suppressing the upward movement of the liquefied gas reservoir 4. On the other hand, when the pressure within the liquefied gas reservoir 4 increases to a positive one due to a suspension of the operation of the cryogenic refrigerator 7 11, although the bellows 16 attempt to expand, the intermediate sealed chamber is held at a constant pressure and therefore the atmospheric pressure within intermediate sealed chamber makes resistance against the expansion actuation, thus suppressing the downward movement of the liquefied gas reservoir 4.
In addition, in order for the liquefied gas reservoir 4 to move along with the retraction of the EDS detector, the cold head 12 is braced to frame 3 through the linear guide mechanism 8 so as to be movable horizontally in back and forth directions (i.e. right and left directions in the upper part of the figure).
The cryogenic refrigerator 11 is adapted to be automatically operated according to the temperature within the liquefied gas reservoir 4. More specifically, the cryogenic refrigerator 11 is so arranged that the ambientatmosphere temperature and liquid temperature are detected by a temperature measuring instrument 17 such as a thermocouple or vaporpressure thermometer, and then a detectedtemperature signal according to the detected temperature detected by the temperature measuring instrument 17 is fed to the compressor unit 13 of the cryogenic refrigerator 11 through a temperature indicator 18 so as to start the operation of the cryogenic refrigerator 11 when the temperature within the liquefied gas reservoir reaches a predetermined high temperature and, in turn, to-stop the operation when the in-reservoir temperature reaches a predetermined low temperature.
These reference values for the operation control, in the case of liquid nitrogen, are set to 72K for the high temperature and 70K for the low, for example. The set value of the high temperature, in this case, is derived from the fact that since even slight vibration is undesirable during the work with the EDS detector and therefore the automatic operation function of the cryogenic refrigerator 11 is the 8 suspended to perform the detection work under the condition of no-operation of the cryogenic refrigerator 11, a high reference temperature 72K is given that takes more than about 8 hours to get liquid nitrogen to reach the boiling temperature 77.34K under the condition of one atmospheric pressure without operation of the cryogenic refrigerator 11.
In the figures, the reference numeral 20 denotes a safety valve which prevents gas pressure within the liquefied gas reservoir 4 from increasing above a predetermined pressure; 21 denotes a pressure gauge which indicates the pressure within the liquefied gas reservoir 4; 22 denotes a gas lead in passageway for refill-ing the liquefied gas reservoir 4 with refrigerant gas of vapor state; and 23 a gas supply control valve interposed in the gas lead-in passageway 22.
Incidentally, the temperature measuring instrument 17 in the above-mentioned embodiment may be substituted by a level gauge so that the gas supply control valve will be controlled for opening and closing according to a liquid level detection signal from the level gauge and also -the cryogenic refrigerator 11 will be controlled for its operation according to the same. In this case, when the liquid level within the liquefied gas reservoir 4 is decreased to a predetermined low level, the gas supply control valve 23 is opened to introduce refrigerant gas of vapor state into the liquefied gas reservoir 4 while the cryogenic refrigerator 11 is put into operation. Then the refrigerant gas--of vapor state introduced therein is condensed by virtue of the coldness arising at the cold end 15 of the cryogenic refrigerator 11, thus being liquefied. Conversely, when the liquid level in the liquefied gas reservoir 4 is increased up to a predetermined high level, the gas supply control valve 23 is closed while the cryogenic refrigerator 11 is stopped operating.
Although each of the embodiments mentioned above uses the bellows 16 as vibration preventive means, it may also be i fl, 9 arranged that the cold head 12 is braced with vibration prevented by the counter-balance method or that some cushioning material such as vibration preventive rubber is f itted b. etween the cold head 12 and the liquefied gas reservoir 4 to render vibration preventive support thereof.

Claims (7)

1. In a liquefied gas reservoir in which a cold finger is coupled with and drawn from a wall thereof and an EDS detector (Energy Dispersive Spectrometer type X-ray detector) is secured thereto, a device -for preventing evaporation of liquefied gas for use with said liquefied gas reservoir charac-:erized in that:
a cold head of a cyrogenic refrigerator is disposed so as to fit an opening at the top of a liquefied gas reservoir, said cold head being braced to a frame with a linear guide mechanism interposed therebetween, said liquefied gas reservoir being braced to said cold head with vibration is preventive means interposed therebetween. and said cold end of said cold head is plunged into said liquefied gas reservoir from said opening at the top thereof so that the temperature within said liquefied gas reservoir can be detected by a temperature measuring instrument, whereby said cyrogenic refrigerator is controlled for the automatic operation thereof according to a temperature within said liquefied gas reservoir detected by said temperature measuring instrument.
2. A device for preventing evaporation of liquefied gas as claimed in claim 1, wherein said vibration preventive means is composed of bellows. ---
3. A devIce for preventing evaporation of liquefied gas as claimed in claim 1, wherein the automatic control of said cyrogenic refrigerator is released according to the starting operation of detection actuation of said EDS detector,, whereas the automatic control of said cyrogenic refrigerator fl is started according to the terminating operation of the detection actuation of said EDS detector.
4. In a liquefied gas reservoir in which a cold finger is coupled with and drawn from a wall thereof and an EDS detector (Energy Dispersive Spectrometer type X-ray detector) is secured thereto, a device for preventing evaporation of liquefied gas for use with said liquefied gas reservoir characterized in that:
a refrigerant gas lead-in passageway is disposed so as to be communicated with an opening at the top of a liquefied gas reservoir, said gas lead-in passageway having a gas supply control valve interposed therein, and a cold head of a cryogenic refrigerator is disposed so as to fit an opening at the top of said liquefied gas reservoir, said cold head being braced to a frame with a linear travel guide mechanism interposed therebetween.. said liquefied ' gas reservoir being braced to said cold head with vibration preventive means interposed therebetween, and said cold end.of said cold head is plunged into said liquefied gas reservoir from said opening at the top thereof so that the liquid level of liquefied gas within said liquefied gas reservoir can be detected by a level gauge, whereby said gas supply control valve is controlled for opening and closing thereof according to the lower-limit liquid level detection actuation by the level gauge while said-- cyrogenic refrigeration is controlled for the automatic operation thereof.
5. A device for preventing evaporation of liquefied gas as claimed in claim 4, wherein said vibration preventive means is composed of bellows.
12
6. A device for preventing evaporation of liquefied gas as claimed in claim 4, wherein the automatic operation of said cyrogenic refrigeration is released according to the starting operation of detection actuation of said EDS detector and also the automatic operation of said cryogenic refrigerator is started according to the terminating operation of detection actuation of said EDS detector.
7. A device__f.or preventing evaporation of liquefied gas in a liquefied gas reservoir used to cool an EDS detector of an electron microscope or the like, whCrein a cold head of a cyrogenic refrigerator is disposed so as to fit an opening of the top of the liquefied gas reservoir and moreover a temperature measuring instrument or a level gauge is is disposed within the liquefied gas reservoir so that the cyrogenic refrigerator is automatically operated depending on the temperature within the liquefied gas reservoir or on change in the liquid level of liquefied gas, whereby vaporized gas is condensed and reliquefied, thus suppressing wasteful dissipation of vaporized gas.
GB9101154A 1991-01-16 1991-01-16 Device for preventing evaporation of liquefied gas in a liquefied gas reservoir Expired - Fee Related GB2251930B (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB9101154A GB2251930B (en) 1991-01-16 1991-01-16 Device for preventing evaporation of liquefied gas in a liquefied gas reservoir
DE19914101786 DE4101786A1 (en) 1991-01-16 1991-01-18 DEVICE FOR PREVENTING EVAPORATION OF LIQUID GAS IN A LIQUID GAS CONTAINER

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9101154A GB2251930B (en) 1991-01-16 1991-01-16 Device for preventing evaporation of liquefied gas in a liquefied gas reservoir

Publications (3)

Publication Number Publication Date
GB9101154D0 GB9101154D0 (en) 1991-02-27
GB2251930A true GB2251930A (en) 1992-07-22
GB2251930B GB2251930B (en) 1994-08-03

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GB9101154A Expired - Fee Related GB2251930B (en) 1991-01-16 1991-01-16 Device for preventing evaporation of liquefied gas in a liquefied gas reservoir

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DE (1) DE4101786A1 (en)
GB (1) GB2251930B (en)

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Publication number Priority date Publication date Assignee Title
DE4302038C2 (en) * 1992-09-25 2001-08-16 Iwatani & Co Device for the production of liquid nitrogen

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GB2251930B (en) 1994-08-03
GB9101154D0 (en) 1991-02-27
DE4101786A1 (en) 1992-07-23

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