US3490247A - Sorption pump roughing system - Google Patents

Sorption pump roughing system Download PDF

Info

Publication number
US3490247A
US3490247A US700216A US3490247DA US3490247A US 3490247 A US3490247 A US 3490247A US 700216 A US700216 A US 700216A US 3490247D A US3490247D A US 3490247DA US 3490247 A US3490247 A US 3490247A
Authority
US
United States
Prior art keywords
pump
molecular sieve
cryosorption
gases
pumping
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.)
Expired - Lifetime
Application number
US700216A
Other languages
English (en)
Inventor
James C Wing
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Applied Biosystems Inc
Original Assignee
Perkin Elmer Corp
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
Application filed by Perkin Elmer Corp filed Critical Perkin Elmer Corp
Application granted granted Critical
Publication of US3490247A publication Critical patent/US3490247A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/38—Exhausting, degassing, filling, or cleaning vessels

Definitions

  • a cryosorption pump adapted for positioning in a bath of liquid coolant comprises an enclosedfparallelopipedshaped body formed of high thermal conductivity metal and having an inlet thereof for the entry of gases being pumped. Means define a generally unrestricted gas passageway through a length of the body and provide a continuous access along the length of the-passage to a surrounding volume of the enclosed body.
  • This volume contains a molecular sieve sorption material-for pumping gases when it is cooled to the temperature of liquid nitrogen.
  • a plurality of elongated metal strips are mounted in thermal transfer relationship with the enclosure body and extend through the volume containing the sorption material. Through this arrangement, efficient thermal transfer is provided between an external coolant and the molecular sieve material while the gases being pumped are provided a substantially unrestricted passageway to the sieve material. The pump thereby provides .a substantially improved pumping characteristic for the quantity of molecular sieve material utilized.
  • This invention relates to vacuum pump arrangements.
  • the invention relates more particularly to a cryosorption roughing pump arrangement.
  • a known technique for evacuating an enclosed atmosphere to all relatively low pressure involves the use of rough or coarse pumping means for initially pumping the enclosure from atmospheric pressure, for example, to a reduced pressure on the order of -3 torr. At this pressure level, an alternate pumping means such as an electronic ion pump which is better adapted for pumping the atmosphere to lower pressure levels is utilized.
  • cryosorption pumping techniques for relatively clean rough pumping have been employed.
  • cryosorption pumping is effected by cooling molecular sieve material to the temperature of liquid nitrogen. At this temperature the molecular sieve material removes gases from the enclosed atmosphere through the mechanisms of absorption and adsorption.
  • the cryosorption pump comprises a generally cylindrically shaped metallic body containing the molecular sieve material and is supported in a coolant reservoir containing liquid nitrogen.
  • a cryogenic container formed of polystyrene is a conventional reservoir for supporting the coolant. Tubes or tubular coils extend through the body for permitting the liquid nitrogen to flow internally of the body for cooling the'inner portions of the relatively low thermal conducting sieve material.
  • the pumping speed and corresponding efficiency of a cryosorption pump are largely dependent upon the operating temperature of the molecular sieve material. Greatest pumping efficiency occurs when the molecular sieve material is maintained at the temperature of liquid nitrogen. However, the sorption mechanism results in the generation of heat which tends to raise the operating temperature of the molecular sieve material and disadvantageously reduces the pumping rate.
  • Another object of the invention is to provide a cryosorption pump having improved thermal transfer means for cooling 4a sorption material.
  • Another object of the invention is to provide a cryosorption pump having improved means for maintaining molecular sieve material at liquid nitrogen temperatures.
  • Another object of the present invention is to provide a cryosorption pump which substantially reduces restrictions in the gas passage without materially increasing pump body size.
  • Various pumping techniques such as sweeping employ a plurality of cryosorption pumps operated in sequence for trapping slowly sorbed gases, such as helium and neon.
  • Known pump body configurations are not readily adaptable for positioning more than one of the bodies in the same coolant reservoir. A sequential pumping arrangement thereby becomes bulky and unwieldy.
  • a further object of the invention is to provide a cryosorption pump having a body configuration adapted for use with one or more similar configurations in one coolant reservoir.
  • Means dene a generally unrestricted gas passageway through a length of the body and provide a continuous access along the length of the passage to a surrounding volume of the enclosed body.
  • This volume contains a molecular sieve sorption material for pumping gases when it is cooled to the temperature of liquid nitrogen.
  • a plurality of elongated metal strips are mounted in thermal transfer relationship with the enclosure body and extend through the volume containing the sorption material.
  • FIG. l is a diagram illustrating a rough pumping system having a cryosorption pump constructed in accordance with features of this invention
  • FIG. 2 is an elevation view partly cut away and partly in section form, illustrating the cryosorption pump of the present invention
  • FIG. 3 is a view, partly in section, of the pump taken along line 3 3 of FIG. 2;
  • FIG. 4 is a sectional view taken along line 4 4 of FIG. 2;
  • FIG. 5 is a sectional view taken along line SAS of FIG. 2;
  • FIG. 6 is a view of a screen body utilized in the pump of FIG. 2;
  • FIG. 7 is a chart illustrating the comparative performance between a pump constructed in accordance with features of this invention and a prior cryosorption pump.
  • an enclosed body 10 which is to be evacuated is coupled to a manifold 12 by suitable tubing 14.
  • Pumping means comprising an oilless mechanical pump 16 and a plurality of cryosorption pumps 17, 18 and 19 are also coupled to the manifold.
  • Suitable valves 20 are provided for coupling these pumps individually or in parallel to the manifold and thus to the body 10.
  • Relief valves 21 are provided between the valves 20 and the pump bodies 17, 18 and 19 for venting pumped gases after use, as indicated in greater detail hereinafter.
  • the oilless mechanical pump 16 comprises a blower having an impellar driven by an electrical motor.
  • the cryosorption pumps each include molecular sieve material for sorption pumping of the body 10.
  • cryosorption pump bodies are supported by'the manifold 12, thereby providing envelopment of the pumps 17, 18 and 19 by the liquid nitrogen.
  • the various tubulations and fittings are sealed in a conventional manner for vacuum use. ⁇
  • FIGS. 246 illustrate in detail one embodiment of a cryosorption pump constructed in accordance with features of the present invention.
  • the pump is shown to include a parallelopiped-shaped enclosed body 30 formed of light gauge, thermally conductive sheet metal.
  • a particularly suitable material is 200 nickel.
  • the particular parallelopiped-shaped body illustrated includes a lrst pair of relatively narrow, planar, oppositely-disposed elongated side members 32 and 34 of length I and depth d and relatively broad, planar, oppositely-disposed elongated side members 36 and 38 of length l and width w.
  • a pump body enclosure is formed by these side members and a top surface member 39 and a lower surface member 40. These members may be separate pieces which are welded to the body, or they may represent integral segments folded over and seam-welded to form the enclosure.
  • a screen body 42 illustrated in perspective in FIG. 6 is provided for dening a substantially unrestricted path in the pump enclosure for gases being pumped from the enclosed body 10.
  • a plurality of such screen bodies are provided and are positioned for extension centrallyV along the length of the pump body.
  • the screen body is formed of a light gauge metal, such as 304 stainless steel, having perforations located on surfaces thereof. The perforation size is selected to prohibit a molecular sieveparticle from passing through the perforations.
  • One surface of the screen body is spot Welded to an associated stiffener 44, which stiffeners are in turn spot welded to the pump body surfaces 36 and 38. The screen bodies are thereby firmly secured within the enclosed pump body.
  • a plurality of elongated, relatively thin sti strips 46 of metal function as heat transfer fins and extend from the surfaces 38 and 36 inwardly toward the screen bodies 42. These strips of metal 46 are 'brazed to and supported by the surfaces 36 and 38 and are formed of a high thermal conductivity material such as 200 nickel. As illustrated in FIGS. 2 and 4, these strips of metal along with the screen bodies 42 compartmentize the inner pump body.
  • a sorption material 47 comprising a conventional molecular sieve material such as crystalline calcium aluminosilicates are disposed in the body and ll these compartments to a level 48, as indicated in FIG. 2.
  • An inlet conduit S is welded to the upper pump body surface 39 and provides access to the interior thereof for gases which are being pumped from the body via the manifold 12.
  • An opposite end of the conduit 50 is coupled to a demountable coupling 52. The gases being pumped from body 10 flow through the conduit 50 and iind substantially unrestricted access to the molecular sieve material via the screened body 42 along the length of the pump body 3l).
  • This pump body arrangement is particularly advantageous in that it provides a relatively high degree of thermal conductivity between the liquid nitrogen 24 and the molecular sieve material 47 throughout the body.
  • the heat generated during the sorption process is thereby e'iciently conducted away from the molecular sieve material, thereby maintaining the molecular sieve material substantially close to liquid nitrogen temperature and effecting a relatively highly eflicient pumping operation.
  • the gases entering the pump body through inlet 50 lind access to the molecular sieve material via a substantially unrestricted passageway through the plurality of screen bodies 42. It has been found that a pump constructed in accordance with the features of this invention for a particular weight of molecular sieve material exhibits substantially improved pumping characteristics over prior cryosorption pumps. k
  • FIG. 7 is a pressure-versus-pumping-time characteristic illustrating the comparative performance of a pump constructed in accordance with features of the present invention and a prior cylindrical pump. Curve illustrates the performance of the prior pump while curve 82 illustrates the performance of the present pump.
  • the test was conducted under similar conditions for each pump in which three pounds of sieve material was employed in a 188L system. The system ywas initially at atmospheric pressure and each pump was subjected to a room-temperature bakeout and a ten-minute prechill.
  • the cryosorption pump is conditioned for re-use after a pumping operation is completed by raising the temperature of the molecular sieve mateiral to about 25 C. or above.
  • the gases which were adsorbed and'. absorbed during the pumping operation are thereby exhausted through the reliefvalves 21.
  • electrical heater rods 60 and 62 are positioned in tubular members 64 and 66, respectively, which extend through the pump body.
  • the tubular members are welded to upper and lower surfaces 39 and 40, and the heater rods extend for the length of the body and are secured in physical contact with the tubes by heater supports 68 and 70 for providing eflicient thermal coupling therebetween.
  • the pump body is therefore advantageous in that it includes relatively noncomplex means for reprocessing the molecular sieve material.
  • the evacuation of body 10 illustrated in FIG. 1 is typically effected by initially operating the oilless mechanical pump 16 While the cryosorption pumps 18 are decoupled from the vacuum system by the valves 20.
  • TheA pump 16 is found to sweep out on the order of 80% of the atmospheric gases contained in the body 10.
  • a first pump 17 of the cryosorption pumps is then coupled to the manifold after pump 16 is decoupled. Pump 17 pumps for a relatively short period of time and then is decoupled.
  • a second pump 18 of the pumps is coupled to the manifold.
  • the third pump 19 is coupled to the manifold after the second pump 18 is decoupled.
  • This method is particularly advantageous in that it effects a sweeping of the neon and helium components and provides for trapping of these components by other gases susceptible to molecular sieve pumping. Decoupling during a gas flow to the pumps also effects trapping.
  • a cryosorption pump has been described which is particularly advantageous in that relatively high and eilicient thermal conductivity is provided for maintaining molecular sieve pump material at liquid nitrogen temperatures to thereby effect eicient pumping.
  • the pump arrangement provides improved access to the pump material for gases being pumped.
  • the parallelopiped pump body configuration is adaptable for locating a plurality of such pumps in one cryogenic container.
  • an improved pump arrangement comprising:
  • an improved pump arrangement comprising:
  • an improved pump arrangement comprising:
  • a hollow parallelopiped-shaped body having a length thereof and formed of a material having a relatively high coefficient of thermal conductivity, said body having an inner surface thereof;
  • said path-defining means comprises a hollow elongated inner body having a plurality of perforations located in a surface thereof.
  • a hollow rectangular parallelopiped-shaped pump body having a length thereof formed by a plurality of metal surfaces, said body having a pair of parallel, oppositely-disposed surfaces;
  • the pump arrangement of claim 7 including a plurality of inner rectangular bodies.
  • the pump arrangement of claim 9 including a tubular member extending longitudinally through said body and means for supporting a heater rod in physical contact with said tubular member.
  • a cryosorption pump comprising:
  • said body having a length l, a width w and a depth d,
  • said body having a pair of oppositely-disposed surfaces defining the length and width for said body;
  • a metal tubular member extending through said body for positioning a heater rod therein;

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
  • Particle Accelerators (AREA)
US700216A 1968-01-24 1968-01-24 Sorption pump roughing system Expired - Lifetime US3490247A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US70021668A 1968-01-24 1968-01-24

Publications (1)

Publication Number Publication Date
US3490247A true US3490247A (en) 1970-01-20

Family

ID=24812633

Family Applications (1)

Application Number Title Priority Date Filing Date
US700216A Expired - Lifetime US3490247A (en) 1968-01-24 1968-01-24 Sorption pump roughing system

Country Status (4)

Country Link
US (1) US3490247A (enrdf_load_stackoverflow)
DE (1) DE1901853A1 (enrdf_load_stackoverflow)
FR (1) FR2000693A1 (enrdf_load_stackoverflow)
GB (1) GB1239192A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3668881A (en) * 1969-12-01 1972-06-13 Air Liquide Adsorptive cryopumping method and apparatus
US4275566A (en) * 1980-04-01 1981-06-30 Pennwalt Corporation Cryopump apparatus
US4339680A (en) * 1978-01-24 1982-07-13 Bbc Brown, Boveri & Company, Ltd. Sorption pump for a turbogenerator rotor with superconductive excitation winding
US4466252A (en) * 1982-09-29 1984-08-21 Cvi Incorporated Cryopump
USRE31665E (en) * 1980-04-01 1984-09-11 Cvi Incorporated Cryopump apparatus
US4494381A (en) * 1983-05-13 1985-01-22 Helix Technology Corporation Cryopump with improved adsorption capacity

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3309844A (en) * 1963-11-29 1967-03-21 Union Carbide Corp Process for adsorbing gases
US3335550A (en) * 1964-04-24 1967-08-15 Union Carbide Corp Cryosorption apparatus
US3344852A (en) * 1964-06-15 1967-10-03 Bergson Gustav Gas drying apparatus
US3371499A (en) * 1966-11-02 1968-03-05 Union Carbide Corp Cryosorption vacuum pumping system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3309844A (en) * 1963-11-29 1967-03-21 Union Carbide Corp Process for adsorbing gases
US3335550A (en) * 1964-04-24 1967-08-15 Union Carbide Corp Cryosorption apparatus
US3344852A (en) * 1964-06-15 1967-10-03 Bergson Gustav Gas drying apparatus
US3371499A (en) * 1966-11-02 1968-03-05 Union Carbide Corp Cryosorption vacuum pumping system

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3668881A (en) * 1969-12-01 1972-06-13 Air Liquide Adsorptive cryopumping method and apparatus
US4339680A (en) * 1978-01-24 1982-07-13 Bbc Brown, Boveri & Company, Ltd. Sorption pump for a turbogenerator rotor with superconductive excitation winding
US4275566A (en) * 1980-04-01 1981-06-30 Pennwalt Corporation Cryopump apparatus
USRE31665E (en) * 1980-04-01 1984-09-11 Cvi Incorporated Cryopump apparatus
US4466252A (en) * 1982-09-29 1984-08-21 Cvi Incorporated Cryopump
US4494381A (en) * 1983-05-13 1985-01-22 Helix Technology Corporation Cryopump with improved adsorption capacity

Also Published As

Publication number Publication date
GB1239192A (enrdf_load_stackoverflow) 1971-07-14
DE1901853A1 (de) 1969-10-09
FR2000693A1 (enrdf_load_stackoverflow) 1969-09-12

Similar Documents

Publication Publication Date Title
US3137551A (en) Ultra high vacuum device
US3296773A (en) Adsorbent-coated thermal panels
US3335550A (en) Cryosorption apparatus
US3264803A (en) Sorption vacuum pump
US3579998A (en) Cryogenic pumping device for the creation of very high vacua
US3024298A (en) Evaporative-gravity cooling systems
US20200054961A1 (en) Systems and methods for cryogenic refrigeration
US6154478A (en) Chemical oxygen-iodine laser (coil)/cryosorption vacuum pump system
US4724677A (en) Continuous cryopump with a device for regenerating the cryosurface
US3490247A (en) Sorption pump roughing system
IL262645B (en) Immersion cooling
US6216467B1 (en) Cryogenic refrigerator with a gaseous contaminant removal system
US3422632A (en) Cryogenic refrigeration system
US3256706A (en) Cryopump with regenerative shield
DE1539159B2 (de) Sortionspumpe
US3116764A (en) High vacuum method and apparatus
JPS61191845A (ja) 希釈低温槽
US3447333A (en) Helium film refrigerator
US3172748A (en) Sorption pump
US3144756A (en) Vacuum system cooling trap
US3321927A (en) Spiral liquid cooled baffle for shielding diffusion pumps
US3360949A (en) Cryopumping configuration
US3197945A (en) Sorption pump apparatus
EP0506133A1 (en) A cryopump
US3525229A (en) On-off thermal switch for a cryopump