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US3387969A - Oxygen scavenging method - Google Patents

Oxygen scavenging method Download PDF

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US3387969A
US3387969A US476767A US47676765A US3387969A US 3387969 A US3387969 A US 3387969A US 476767 A US476767 A US 476767A US 47676765 A US47676765 A US 47676765A US 3387969 A US3387969 A US 3387969A
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zirconium
alkali metal
oxygen scavenging
membrane
alloy
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US476767A
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Stanley B Skladzien
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US Atomic Energy Commission (AEC)
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Atomic Energy Commission Usa
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B26/00Obtaining alkali, alkaline earth metals or magnesium
    • C22B26/10Obtaining alkali metals
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S266/00Metallurgical apparatus
    • Y10S266/905Refractory metal-extracting means

Definitions

  • the invention relates to a method for removing oxide from molten alkali metal and maintaining the alkali metal in an oxide free condition.
  • scavenger a continuous thin zirconium-containing membrane, one surface of which is in contact with the alkali metal, the other with a molten calcium containing metal, which regenerates the membrane by virtue of the unique diffusion of oxide therethrough.
  • FIGURE 1 is a vertical, partially sectional view of the apparatus.
  • FIGURE 2 is an enlarged vertical sectional view of the bottom portion of FIGURE 1.
  • the containing vessel 2 consists of an upper shell 4 and a lower shell 6, each shell being constructed of A" thick (AISI designation) 304 stainless steel.
  • Shells 4 and 6 are cylinders 16" OD, 15" high. At their mating ends they are joined to flange-s 8, 19" OD.
  • Upper shell 4 is completed with conical top 10, rising 2" and joined to nipple 12, 3 OD, 2" high terminating with 7 /2 diameter top flange 14.
  • Lower shell 6 is closed by skewed conical bottom 16, through which a 3" long, 2" OD nipple 18 is axially positioned. Nipple 18 is connected to flange 20, which is 7 /2" OD. At the lowest point of conical bottom 16, drain pipe 22, a length of OD tubing extends downward. At some point on pipe 22, a valve (not shown) permits the contents of containing vessel 2 to be drained, when desired. Inlet line 24 and outlet line 26 are attached to the lower shell 6 and upper shell 4 respectively, at opposite sides, 11" from the mating surfaces of flanges 8.
  • tubes 32 are provided, each of which is a membrane 3,387,;369 Patented June 11, 1968 as mentioned above and is formed of zirconium or a zirconium alloy such as Zircaloy-II.
  • Each tube is 12" long and thick and has an outside diameter of 1".
  • the tubes are parallel and have their axis on the corners of equilateral triangles 1 on a side, so that each tube, except the outermost ones, is surrounded by six tubes that have an axis spacing of 1 from one another and from said each tube.
  • the tubes 37 as a group present the general outline of a regular hexagon.
  • the tubes are inserted into tube sheets 34, which take the form of discs of thick, 14" diameter and are formed of zirconium 0r zirconium alloy.
  • Closure is completed by inert arc welding.
  • Upper manifold 38 is a A shallow conical vessel, to which is attached upper conduit 40, which is A in thickness and 2 /2" in OD and is formed of zirconium or zirconium alloy.
  • the upper end of conduit 40 leads to a molten calcium alloy storage vessel (not shown).
  • Flow is controlled by a conventional valve (not shown).
  • Lower manifold 42 is a conical vessel of zirconium or zirconium alloy, deeply sloped to avoid collection of sediment, terminating in outlet conduit 44 thick, 1 /2" OD. This conduit 44 terminates in a valve, symbolically shown, which regulates the flow of molten metal to a receiving vessel (not shown).
  • discs 52 of zirconium or zirconium alloy, /8 thick, 6 /2" OD, are positioned on upper conduit 40 and outlet conduit 44 and welded in place by inert arc welding.
  • Flanges 14 and 20 are grooved to accommodate hollow zirconium 0 rings 50.
  • against these 0 rings 50 are positioned discs 52 welded in position in situ, using inert arc welding.
  • Closure is completed by positioning upper centering flange 54 and lower centering flange 56 against discs 52.
  • Bolts 58 complete the seal. Heating is accomplished by conventional means, preferably by inductive heat.
  • Optimum operating temperature is l200l300 F. This temperature is below the melting point of calcium, so that it is desirable to add sufficient magnesium to approach one of the eutectics, in the neighborhood of 21% magnesium by weight. A range of 1530% magnesium should operate satisfactorily.
  • the present invention is employed to remove oxygen from sodium that is relatively low in oxygen contamination, for example, about 10 parts per million. This condition will have been reached by one or two treatments of the sodium in a cold trap that has wire mesh on which the oxygen is trapped out when the sodium temperatures drop below the saturation temperature, but not below about 225 F.
  • a method of removing oxide from alkali metal comprising flowing said alkali metal past a membrane of 3 y v4-1 zirconium or zirconium alloy maintained at an elevated References Cited 2.
  • the method of claim 1 where the temperature is 2813O19 11/1957 Olson 75 66 X maintained at 1200 130O F 5 2,815,277 12/1957 Bruggeman et a1.
  • the method of claim 1 where the calcium containing alloy consists essentially of calcium and 15-30 weight HYLAND BIZOT Pnmary f percent of magnesium. H. W. TARRING, Assistant Examiner.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Description

United States Patent 3,387,969 OXYGEN SCAVENGING METHOD Stanley B. Skladzien, Elmhurst, Ill., assignor to the United States of America as represented by the Chairman of the United States Atomic Energy Commission Filed Aug. 2, 1965, Ser. No. 476,767 3 Claims. (Cl. 75-66) The invention relates to a method for removing oxide from molten alkali metal and maintaining the alkali metal in an oxide free condition.
In many alkali metal systems it is very important to keep oxide content as low as possible. The presence of oxide in the alkali metal substantially increases the corrosiveness of the alkali metal to many metals. Such metals are necessarily used for containers and other mechanical parts.
There are a number of presently available devices that can accomplish this purpose. All that is needed is a container filled with material that can scavenge oxide from the molten alkali metal. This scavenger can be in any bulky form offering a large amount of surface to the molten alkali metal.
However, these devices suffer from a number of severe shortcomings. It is extremely difiicult to determine when the scavenger material is exhausted and severe damage may result before this becomes known. Further, these devices are normally fabricated into a closed system so that the system must be opened to replace a unit. With the known tendency of alkali metal to wet and adhere to metal surfaces, and its tendency to catch fire in air, such a change is a major undertaking.
It is an object of this invention to provide a method by which the oxygen scavenging material is continuously and automatically regenerated.
It is also an object of this invention to provide a deoxidizing device which will function uniformly during its entire life.
It is a further object of this invention to provide a device which eliminates the need of frequent, troublesome replacements.
This is accomplished by providing as the scavenger, a continuous thin zirconium-containing membrane, one surface of which is in contact with the alkali metal, the other with a molten calcium containing metal, which regenerates the membrane by virtue of the unique diffusion of oxide therethrough.
In the drawing:
FIGURE 1 is a vertical, partially sectional view of the apparatus; and
FIGURE 2 is an enlarged vertical sectional view of the bottom portion of FIGURE 1.
Referring to FIGURE 1, the containing vessel 2 consists of an upper shell 4 and a lower shell 6, each shell being constructed of A" thick (AISI designation) 304 stainless steel. Shells 4 and 6 are cylinders 16" OD, 15" high. At their mating ends they are joined to flange-s 8, 19" OD. Upper shell 4 is completed with conical top 10, rising 2" and joined to nipple 12, 3 OD, 2" high terminating with 7 /2 diameter top flange 14.
Lower shell 6 is closed by skewed conical bottom 16, through which a 3" long, 2" OD nipple 18 is axially positioned. Nipple 18 is connected to flange 20, which is 7 /2" OD. At the lowest point of conical bottom 16, drain pipe 22, a length of OD tubing extends downward. At some point on pipe 22, a valve (not shown) permits the contents of containing vessel 2 to be drained, when desired. Inlet line 24 and outlet line 26 are attached to the lower shell 6 and upper shell 4 respectively, at opposite sides, 11" from the mating surfaces of flanges 8.
37 tubes 32 are provided, each of which is a membrane 3,387,;369 Patented June 11, 1968 as mentioned above and is formed of zirconium or a zirconium alloy such as Zircaloy-II. Each tube is 12" long and thick and has an outside diameter of 1". The tubes are parallel and have their axis on the corners of equilateral triangles 1 on a side, so that each tube, except the outermost ones, is surrounded by six tubes that have an axis spacing of 1 from one another and from said each tube. The tubes 37 as a group present the general outline of a regular hexagon. The tubes are inserted into tube sheets 34, which take the form of discs of thick, 14" diameter and are formed of zirconium 0r zirconium alloy. Closure is completed by inert arc welding. On each tube sheet 34, circular bands 36 1" wide, 16" thick extend outward. Upper manifold 38 is a A shallow conical vessel, to which is attached upper conduit 40, which is A in thickness and 2 /2" in OD and is formed of zirconium or zirconium alloy. The upper end of conduit 40 leads to a molten calcium alloy storage vessel (not shown). Flow is controlled by a conventional valve (not shown). Lower manifold 42 is a conical vessel of zirconium or zirconium alloy, deeply sloped to avoid collection of sediment, terminating in outlet conduit 44 thick, 1 /2" OD. This conduit 44 terminates in a valve, symbolically shown, which regulates the flow of molten metal to a receiving vessel (not shown).
After assembly, discs 52 of zirconium or zirconium alloy, /8 thick, 6 /2" OD, are positioned on upper conduit 40 and outlet conduit 44 and welded in place by inert arc welding. Flanges 14 and 20 are grooved to accommodate hollow zirconium 0 rings 50. Against these 0 rings 50 are positioned discs 52 welded in position in situ, using inert arc welding. Closure is completed by positioning upper centering flange 54 and lower centering flange 56 against discs 52. Bolts 58 complete the seal. Heating is accomplished by conventional means, preferably by inductive heat.
Obviously, other simple modifications could be used to carry out the teachings of the patent. All that is necessary is to provide approximately 20 30 square feet of thin walled zirconium or zirconium alloy such as Zircaloy- II, with contact on one surface with calcium metal and the alkali metal to be cleaned on the other surface.
Due to the ease of brittle compound formation between zirconium and iron alloys, such as stainless, all joints between these metals must be mechanical. Welding such members is not desirable.
Optimum operating temperature is l200l300 F. This temperature is below the melting point of calcium, so that it is desirable to add sufficient magnesium to approach one of the eutectics, in the neighborhood of 21% magnesium by weight. A range of 1530% magnesium should operate satisfactorily.
The present invention is employed to remove oxygen from sodium that is relatively low in oxygen contamination, for example, about 10 parts per million. This condition will have been reached by one or two treatments of the sodium in a cold trap that has wire mesh on which the oxygen is trapped out when the sodium temperatures drop below the saturation temperature, but not below about 225 F.
The need to employ the present invention to obtain sodium with less than 10 ppm. oxygen comes from the trend to higher temperatures and use of refractory metals for jackets in sodium reactor systems.
It is to be understood that the invention is not to be limited to the specific design shown or the details presented, but only by the scope of the appended claims.
The embodiment of the invention in which an exclusive property or privilege is claimed are define-d as follows:
1. A method of removing oxide from alkali metal comprising flowing said alkali metal past a membrane of 3 y v4-1 zirconium or zirconium alloy maintained at an elevated References Cited 2. The method of claim 1 where the temperature is 2813O19 11/1957 Olson 75 66 X maintained at 1200 130O F 5 2,815,277 12/1957 Bruggeman et a1. 75-66 3. The method of claim 1 where the calcium containing alloy consists essentially of calcium and 15-30 weight HYLAND BIZOT Pnmary f percent of magnesium. H. W. TARRING, Assistant Examiner.

Claims (1)

1. A METHOD OF REMOVING OXIDE FROM ALKALI METAL COMPRISING FLOWING SAID ALKALI METAL PAST A MEMBRANE OF ZIRCONIUM OR ZIRCONIUM ALLOY MAINTAINED AT AN ELEVATED TEMPERATURE, MEANWHILE FLOWING A CALCIUM-CONTAINING ALLOY ON THE OTHER SIDE OF SAID MEMBRANE.
US476767A 1965-08-02 1965-08-02 Oxygen scavenging method Expired - Lifetime US3387969A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3483913A (en) * 1967-03-22 1969-12-16 Atomic Energy Commission Method of molten metal separation
US3622303A (en) * 1966-05-23 1971-11-23 Atomic Power Dev Ass Inc Method for removing hydrogen from liquid alkali metals and the like

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2813019A (en) * 1951-10-12 1957-11-12 Du Pont Method of producing zirconium metal
US2815277A (en) * 1953-09-02 1957-12-03 Warren H Bruggeman Method for removing sodium oxide from liquid sodium

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2813019A (en) * 1951-10-12 1957-11-12 Du Pont Method of producing zirconium metal
US2815277A (en) * 1953-09-02 1957-12-03 Warren H Bruggeman Method for removing sodium oxide from liquid sodium

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3622303A (en) * 1966-05-23 1971-11-23 Atomic Power Dev Ass Inc Method for removing hydrogen from liquid alkali metals and the like
US3483913A (en) * 1967-03-22 1969-12-16 Atomic Energy Commission Method of molten metal separation

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