WO1986005240A1 - Procede et dispositif de regeneration de cryopompes - Google Patents

Procede et dispositif de regeneration de cryopompes Download PDF

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Publication number
WO1986005240A1
WO1986005240A1 PCT/US1986/000462 US8600462W WO8605240A1 WO 1986005240 A1 WO1986005240 A1 WO 1986005240A1 US 8600462 W US8600462 W US 8600462W WO 8605240 A1 WO8605240 A1 WO 8605240A1
Authority
WO
WIPO (PCT)
Prior art keywords
cryopump
gas
stage
array
nitrogen
Prior art date
Application number
PCT/US1986/000462
Other languages
English (en)
Inventor
Bruce R. Andeen
Robert C. Pandorf
Original Assignee
Helix Technology Corporation
Priority date (The priority date 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 date listed.)
Filing date
Publication date
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Application filed by Helix Technology Corporation filed Critical Helix Technology Corporation
Priority to DE8686902122T priority Critical patent/DE3671940D1/de
Publication of WO1986005240A1 publication Critical patent/WO1986005240A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B37/00—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00
    • F04B37/06—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for evacuating by thermal means
    • F04B37/08—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for evacuating by thermal means by condensing or freezing, e.g. cryogenic pumps
    • F04B37/085—Regeneration of cryo-pumps

Definitions

  • This invention relates to the regeneration of cryopumps.
  • a low temperature array usually operating in the range of 4 to 25 K, is the primary pumping surface. This surface is surrounded by a higher temperature radiation shield, usually operated in the temperature range of 70 to 130 K, which provides radiation shielding to the lower temperature array.
  • the radiation shield generally comprises a housing which is closed -except at a frontal array positioned between the primary pumping surface and the chamber to be evacuated. This higher temperature, first stage frontal array serves as a pumping site for higher boiling point gases such as water vapor.
  • high boiling point gases such as water vapor are condensed on the frontal array.
  • Lower boiling point gases pass through that array and into the volume within the radiation shield and condense on the lower temperature array.
  • a surface coated with an adsorbent such as charcoal or a molecular sieve operating at or below the temperature of the colder array may also be provided in this volume to remove the very low boiling point gases such as hydrogen.
  • the cooler is typically a two stage refrigerator having a cold finger which extends through the rear of the radiation shield. The cold end of the second, coldest stage of the cryocooler is at the tip of the cold finger.
  • the primary pumping surface, or cryopanel is connected to a heat sink at the coldest end of the second stage of the cold- finger.
  • This cryopanel may be a simple metal plate or an array of metal baffles arranged around and connected to the second stage heat sink.
  • This second stage cryopanel also supports the low temperature adsorbent.
  • the radiation shield is connected to a heat sink, or heat station at the coldest end of the first stage of the refrigerator.
  • the shield surrounds the second stage cryopanel in such a way as to protect it from radiant heat.
  • the frontal array is cooled by the first stage heat sink through the side shield or,, as disclosed in U. S. Patent 4,356,701, through thermal struts.
  • the gases which have condensed onto the cryopanels, and in particular the gases which are adsorbed, begin to saturate the system.
  • a regeneration procedure must then be followed to warm the cryopump and thus release the gases and remove the gases from the system.
  • the gases evaporate, the pressure in the cryopump increases.
  • the gases are exhausted from the cryopump at about 18 pounds per square inch (PSIA) .
  • PSIA pounds per square inch
  • the cryopump is often purged with warm nitrogen gas. The nitrogen gas hastens warming of the cryopanels and also serves to flush water and other vapors from the system.
  • the nitrogen " gas which flows outward to the exhaust port prevents the flow of water vapor from the first stage array back to the second stage array.
  • Nitrogen is the usual purge gas because it is inert.
  • the nitrogen gas dilutes any mixture of combustible gases such as hydrogen and oxygen which may be released by the cryopump.
  • the adsorbent on the second stage array is generally the component of the system which first requires regeneration.
  • the amount of adsorbent carried by the second stage is increased.
  • an increased amount of adsorbent increases the amount of hydrogen which can be collected by the system and thus also increases the danger due to combustion of the hydrogen during regeneration.
  • gases which evaporate during regeneration are evacuated from the cryopump by means of an ejector pump.
  • an inert gas such as nitrogen to actuate the ejector pump
  • any released inflammable gas may be further diluted with inert gas to minimize the danger of combustion external to the vacuum vessel.
  • the amount of hydrogen which mixes with the later evaporated oxygen in the cryopump is substantially reduced.
  • the pressure of the cryopump chamber the system may be held, in the unlikely event of combustion within the chamber, to acceptable pressure levels.
  • the cryopump of Fig. 1 comprises a main housing 12 which is mounted to a work chamber or a valve housing 13 along a flange 14.
  • a front opening 16 in the cryopump housing 12 communicates with a circular opening in the work chamber or valve housing.
  • the.cryopump arrays may protrude into the chamber and. a vacuum seal be made ' at a rear flange.
  • a two stage cold finger 18 of a refrigerator protrudes into the housing 12 through an opening 20.
  • the refrigerator is a Gifford-MacMahon refrigerator but others may be used.
  • a two stage displacer in the cold finger 18 is driven by a motor 22. With each cycle, helium gas introduced into the cold finger under pressure through line 26 is expanded and thus cooled and then exhausted through line 24.
  • a first stage heat sink. or heat station 28 is mounted at- the cold end of the first stage 29 of the refrigerator.
  • a heat sink 30 is mounted to the cold end of the second stage 32. Suitable temperature sensor and vapor pressure sensor elements 34 and 36 are mounted to the rear of the heat sink 30.
  • the primary pumping surface is a cryopanel array mounted to the heat sink 30.
  • This array comprises a disc 38 and a set of circular chevrons 40 arranged in a vertical array and mounted to disc 38.
  • the cylindrical surface 42 holds a low temperature adsorbent. Access to this adsorbent by low boiling point gases is through chevrons.
  • a cup shaped radiation shield 44 is mounted to the first stage, high temperature heat sink 28. The second stage of the cold finger extends through an opening 45 in that radiation shield.
  • This radiation shield 44 surrounds the primary cryopanel array to the rear and sides to minimize heating of the primary cryopanel array by radiation.
  • the temperature of this radiation shield ranges from about 100° K. at the heat sink 28 to about 130° K. adjacent to the opening 16.
  • a frontal cryopanel array 46 serves as both a radiation shield for the primary cryopanel array and as a cryopu ping surface for higher boiling temperature gases such as water vapor.
  • This panel comprises a circular array of concentric louvers and chevrons 48 joined by spoke-like plates 50.
  • the configuration of this cryopanel 46 need not be confined to circular concentric components; but it should be so arranged as to a as a radiant heat shield and a higher temperature cryopumping panel while providing a path for lower boiling temperature gases to the primary cryopanel.
  • Thermal struts 54 extend between a plate 56 mounted to the heat sink 28 and the frontal array. Those struts extend through clearance openings 58 in the primary panel 38 and are thus isolated from that panel.
  • the cryopump is regenerated by turning off the refrigerator and allowing the system to warm. As the temperature of the system increases the gases evaporate thus increasing the pressure in the system. As the pressure reaches about 18 PSIA the released gases are exhausted from the system through a relief valve 60.
  • a warm inert gas such as nitrogen may be introduced from a supply 62 through a valve 64 and a purge port 66.
  • the purge port releases the nitrogen near to the second stage array to minimize the back flow of water vapor from the first stage array to the second stage.
  • gas which is released from the cryopump during regeneration is removed rapidly from the system through a valve 68 by means of an ejector 70.
  • An ejector also referred to as jet pump or venturi pump, aspirates the gas from the cryopump chamber by means of a high velocity jet of fluid from a nozzle 72 or some other venturi for generating high velocity flow.
  • the actuating fluid forced through the nozzle 72 is nitrogen gas valved through a valve 74 from the nitrogen supply 62.
  • Nitrogen gas is inert, that is it does not react with the hydrogen or oxygen in the system. The nitrogen thus further dilutes the hydrogen and oxygen which is aspirated from the cryopump.
  • An alternative ejector in which the aspirated fluid is drawn through a side port in a venturi is the Ultravak TM air ejector available from Air-Vak
  • the present system serves to minimize the danger of any combustion in the cryopump housing by reducing the pressure.
  • the pressure can increase approximately seven-fold.
  • the pressure can be expected to rise to 7 atmospheres in the event of combustion.
  • the pressure in the vacuum chamber remains at safe levels.
  • the present system further minimizes the dangers of combustion by reducing the amount of hydrogen and oxygen which are mixed at any given time in the cryopump chamber.
  • Much of the hydrogen is released from the adsorbent before oxygen is evaporated from the cryopanels.
  • By evacuating the cryopump chamber as the hydrogen is released most of the hydrogen can be removed before a significant amount of oxygen is evaporated.
  • the nitrogen purge is less necessary with the use of an aspirator, the nitrogen may still be useful in helping to warm the system, to dry the system, and to initially dilute the released gases before they reach the ejector.

Abstract

Une cryopompe est régénérée à l'aide d'une pompe à éjection (70) qui aspire le gaz de la cryopompe, pendant que cette dernière est chauffée. L'éjecteur (70) est actionné par un gaz inerte. Ce même gaz inerte peut être utilisé pour purger la pompe pendant l'évacuation.
PCT/US1986/000462 1985-03-01 1986-03-03 Procede et dispositif de regeneration de cryopompes WO1986005240A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE8686902122T DE3671940D1 (de) 1985-03-01 1986-03-03 Verfahren und vorrichtung zum regenerieren einer kryopumpe.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US70746785A 1985-03-01 1985-03-01
US707,467 1985-03-01

Publications (1)

Publication Number Publication Date
WO1986005240A1 true WO1986005240A1 (fr) 1986-09-12

Family

ID=24841815

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1986/000462 WO1986005240A1 (fr) 1985-03-01 1986-03-03 Procede et dispositif de regeneration de cryopompes

Country Status (4)

Country Link
EP (1) EP0214277B1 (fr)
JP (1) JPS62502276A (fr)
DE (1) DE3671940D1 (fr)
WO (1) WO1986005240A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993021441A1 (fr) * 1992-04-16 1993-10-28 Helix Technology Corporation Vidange d'eau pour pompe cryogenique
WO1995011381A1 (fr) * 1993-10-22 1995-04-27 Leybold Aktiengesellschaft Procede d'exploitation d'une pompe cryogenique et systeme de pompes a vide comprenant une pompe cryogenique et une pompe a vide preliminaire
GB2283063B (en) * 1992-06-12 1996-04-17 Helix Tech Corp Cryopump and cyropanel having a frost concentrating device
WO1997035111A1 (fr) * 1996-03-20 1997-09-25 Helix Technology Corporation Procede de regeneration de cryopompe par purge et vidange prealable, cryopompe et organe de commande
FR2747452A1 (fr) * 1996-04-12 1997-10-17 Helix Tech Corp Robinet d'evacuation, procede de rechauffement de ce robinet, et pompe cryogenique le comportant
US9605667B2 (en) 2013-03-19 2017-03-28 Sumitomo Heavy Industries, Ltd. Cryopump and method for vacuum pumping non-condensable gas

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI580865B (zh) * 2013-03-25 2017-05-01 Sumitomo Heavy Industries Low temperature pump

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1380205A (fr) * 1964-01-21 1964-11-27 Leybold Hochvakuum Anlagen Trompe d'aspiration à jet de gaz
WO1984000404A1 (fr) * 1982-07-06 1984-02-02 Helix Tech Corp Organe de desorption periodique d'une cryopompe
CH652804A5 (en) * 1981-03-10 1985-11-29 Balzers Hochvakuum Method for regenerating the low-temperature condensation surfaces of a cryopump and cryopump appliance for implementing the method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1380205A (fr) * 1964-01-21 1964-11-27 Leybold Hochvakuum Anlagen Trompe d'aspiration à jet de gaz
CH652804A5 (en) * 1981-03-10 1985-11-29 Balzers Hochvakuum Method for regenerating the low-temperature condensation surfaces of a cryopump and cryopump appliance for implementing the method
WO1984000404A1 (fr) * 1982-07-06 1984-02-02 Helix Tech Corp Organe de desorption periodique d'une cryopompe

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Solid State Technology, Vol. 25, No. 1, January 1982 (Port Washington, US) J.F. PETERSON et al.: "Vacuum Pump Technology; a Short Course on Theory and Operations", pages 104-110, see page 107, right-hand column, paragraph "Regeneration" - page 108, right-hand column, paragraph 1 *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993021441A1 (fr) * 1992-04-16 1993-10-28 Helix Technology Corporation Vidange d'eau pour pompe cryogenique
US5333466A (en) * 1992-04-16 1994-08-02 Helix Technology Corporation Cryopump water drain
GB2283063B (en) * 1992-06-12 1996-04-17 Helix Tech Corp Cryopump and cyropanel having a frost concentrating device
WO1995011381A1 (fr) * 1993-10-22 1995-04-27 Leybold Aktiengesellschaft Procede d'exploitation d'une pompe cryogenique et systeme de pompes a vide comprenant une pompe cryogenique et une pompe a vide preliminaire
WO1997035111A1 (fr) * 1996-03-20 1997-09-25 Helix Technology Corporation Procede de regeneration de cryopompe par purge et vidange prealable, cryopompe et organe de commande
FR2746453A1 (fr) * 1996-03-20 1997-09-26 Helix Tech Corp Pompe cryogenique, et procede et organe de commande de regeneration de pompe cryogenique
GB2325707A (en) * 1996-03-20 1998-12-02 Helix Tech Corp Purge and rough cryopump regeneration process cryopump and controller
GB2325707B (en) * 1996-03-20 2000-06-21 Helix Tech Corp Purge and rough cryopump regeneration process, cryopump and controller
FR2747452A1 (fr) * 1996-04-12 1997-10-17 Helix Tech Corp Robinet d'evacuation, procede de rechauffement de ce robinet, et pompe cryogenique le comportant
WO1997039242A1 (fr) * 1996-04-12 1997-10-23 Helix Technology Corporation Cryopompe avec une valve de sortie chauffee par du gaz
US5906102A (en) * 1996-04-12 1999-05-25 Helix Technology Corporation Cryopump with gas heated exhaust valve and method of warming surfaces of an exhaust valve
US9605667B2 (en) 2013-03-19 2017-03-28 Sumitomo Heavy Industries, Ltd. Cryopump and method for vacuum pumping non-condensable gas

Also Published As

Publication number Publication date
EP0214277A1 (fr) 1987-03-18
DE3671940D1 (de) 1990-07-19
JPS62502276A (ja) 1987-09-03
EP0214277B1 (fr) 1990-06-13

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