US3902658A

US3902658A - Ultra centrifugal cascade

Info

Publication number: US3902658A
Application number: US258823A
Authority: US
Inventors: Kristian Dahl Madsen
Original assignee: ASEA AB
Current assignee: ABB Norden Holding AB
Priority date: 1971-06-07
Filing date: 1972-06-01
Publication date: 1975-09-02
Anticipated expiration: 1992-09-02
Also published as: GB1383124A; SE354200B; DE2227317A1

Abstract

An ultra centrifuge cascade has centrifuge cascade groups mounted between horizontal upper and lower plates and enclosed by a common containment vessel for all of the centrifuges, the latter being positioned vertically and parallel to each other between the plates, all piping being also enclosed by the common or single containment vessel.

Description

Sept. 2, 1975 Madsen WM H Wm WM mm 5 n m e mam k CSWk 00267 66666 99999 11111 58903 1 02476 706 672 9 34580 99 1 22333 ULTRA CENTRIFUGAL CASCADE [75] Inventor: Kristian Dahl Madsen, Vasteras,

Sweden [73] Assignee: Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden June 1, 1972 Appl. No.: 258,823

[22] Filed:

Primary Examiner-George H. Krizmanich Attorney, Agent, or FirmKenyon & Kenyon Reilly Carr & Chapin 1 [30] Foreign Application Priority Data June 7, 1971 Sweden......1........................ 7308/71 [57] ABSTRACT An ultra centrifuge cascade has centrifuge cascade 233/11; 233/18; 233/27 B04b 15/02 1 C [52] U.S.Cl.......

groups mounted between horizontal upper and lower plates and enclosed by a common containment vessel for all of the centrifuges, the latter being positioned vertically and parallel to each other between the [58] Field of Search.......... 233/11, 1 R,

References Cited UNITED STATES PATENTS plates, all piping being also enclosed by the common or single containment vessel.

2,663,718 Strezynski......................... 233/18 x 2,779,537 1/1957 Madany.t........i........... 233/18 x 9 Claims, 6 Drawlng Figures ULTRA CENTRIFUGAL CASCADE The present invention relates to an ultra centrifugal cascade, complete or partial, in a common outer vessel.

Such cascades are already known (see German Pat. No. 1,191,750) but it is a problem to achieve a stable construction of the various centrifuges in a cascade adjacent each other and to protect the various centrifuges against damage if an adjacent centrifuge breaks down, at the same time avoiding complicated pipe-laying, etc. for transfer and cooling tubes.

The present invention provides a solution of these and other similar problems and is characterized in that several, possibly all the ultra centrifugal rotors and possibly also their drive members are attached in common upper and lower perforated plates arranged inside an outer vessel common for the centrifuges. Such a construction utilizes the space inside the vessel to the full while at the same time providing satisfactory stability in relation to the vessel and between the centrifuges. The arrangement of the centrifuges in groups, with intermediate protection in the form of protective plates or rows of protective tubes, is'simple and the mutual configuration of the groups can be selected in many dif ferent ways without the need for reconstruction. The arrangement of the centrifuges in this way ina common vessel also means that the wall thickness of protective plates and casing plate will be as great as the plate thickness which would be required to protect a single centrifuge and, therefore, the arrangement according to the invention also involves a considerable saving in material.

The accompanying drawings show presently preferred modes for carrying out the invention.

FIG. 1 is a section through a centrifuge,

FIG. 2 a cascade vessel, partly exposed, I

FIG. 3 a cross-section through a cascade vessel,

FIG. 4 a pipe-laying diagram for a cascade and FIG. 5 a cooling system for a cascade.

Finally, FIG. 6 shows a cascade connection diagram.

FIG. 1 shows a single, vertical centrifuge C which is part of a cascade (see below). A hollow rotor consisting of a cylindrical part 17 and two

end pieces

14 and 15, is journalled in an upper perforated plate 33 via one of its perforations 33a. The rotor is driven by an asynchronous motor (rotor 12, stator 13) or other drive means and the lower part of the non-rotative motor box 13a is attached in a lower perforated plate 29 (or grid plate 29) via one of its perforations 29a. Lubrication is arranged via a lubricant storage space in a depending chamber 20 containing a lubricant wick 21 extending to the lower rotor bearing 19. The upper and lower perforated plates and 29, respectively, are held together by support pipes 32. The centrifuge rotor is journalled at its top in an upper electromagnetic bearing 22 supported on the upper plate 36 via its upper surface.

The gas or isotope mixture to be separated is introduced through thepipe 23, possibly coming from .a previous centrifuge or group or centrifuges in a cascade, and the concentrated gas is removed through the con duit 24, the depleted gas being removed through the conduit 25. The gas is withdrawn from the interior of the rotor R through

exhausts

27 and 28. The motor stator 13 is attached in the motor box 13a the latter having a flange 18 attached to the lower perforated plate 29 via its lower surface. An upstanding tube 16 connected to the top of the bearing 22, houses the

conduits

23, 24,and 25 and mounts the

exhausts

27 and 28 nonrotatively via the tube 26.

FIG. 2 shows a vessel for a centrifugal cascade with the various centrifuges C attached in the upper and lower

perforated plates

36 and 29, respectively, and the whole cascade arranged inside the cylindrical containment casing37. The individual centrifuges are shown at C, vertically positioned and parallel to each other, the casings axis being vertical.

- FIG. 3shows in cross-section a centrifugal cascade such as illustrated by FIG. 2, having rows of protective vertical tubes 40 which separate groups of the centrifuges C from other groups of these centrifuges so that a break down of one centrifuge will not cause any damage except possibly to those centrifuges within the same limited group within the cascade, the others being protected by the row of protective tubes 40. The rows of protective tubes may be replaced by protective plates. This means of protection gives the advantage that whereas a protection was previously required around each centrifuge, such protection is now sufficient only at the outer walls of the vessel and/or between groups of centrifuges, which is a considerable saving in material. I

FIG. 6 shows diagrammatically the invention used as an ultra centrifugal cascade in which U 0.71 percent is to be separated so that concentrated U is obtained. U is also contained in the depleting part. Unseparated gas (or isotope mixture) is introduced at 42 and initially separated in fourteen centrifuges operating inparallel as indicated by the upper box 14, after which the partially enriched gas mixture is fed in the enriching direction (upwards in the figure) to the next layer or group in the cascade which has ten centrifuges operating in parallel as indicated by the upper box 10. The number is fewer here because the quantity of gas is less as indicated by .the encircled numerals representing flow. quantity. Depleted gas is carried at 24 to the nearestpreceding group where it is introduced at 23 and en riched again. At the end of the enriching process only one centrifuge is in operation, as can be seen from the upper box 1, and the enriched gas contains 2.1 percent U It is seen that depleted gas in all the groups is led to a preceding centrifuge in the cascade direction.

Depleted gas, 0.25 percent U is removed from the three centrifuges, represented by the lower box 14, furthest away in the depletion direction, which operate in parallel.

The underlined number in each .of the boxes represents the number of centrifuges of FIG. 1, connected in parallel to form a cascade stage in all of the above.

FIG. 4 shows the pipe system for gas transfer between the various cascade groups, in principle in accordance with FIG. 6. Natural UF is supplied to a cascade at 44 and from this branching point the gas mixture is introduced to common pipe conduits (main conduits) for several centrifuges within the same group. The various groups (see FIG. 6) are designated 1 to 11 in FIG. 4, one figuredenoting centrifuges belonging to the same group but in this case not indicating groups of centricentrifuges operating in parallel and in the enriching direction the partically U enriched gas is taken out through

conduits

46 and 47, connection details not shown but being the same as in the depleting direction and shown at 23, 24 and 25 in that instance. In this way all complicated pipe-laying is avoided using a large number of pipes, and all pipes are located within the casing 37. This means that any leakage at pipe joints will only have any effect inside the cascade vessel.

Depleted gas is removed at 48 from group 1, enriched gas at 49 from group 11. I

The cooling system is shown in FIG. and consists of a number of

horizontal tubes

30 and 31 which run in contact with the upper and lower horizontal perforated plates 29, 36 (see FIG. 1), not vertically along the length of the centrifuges between the perforated plates.

The number of cooling systems is thus reduced to one per cascade instead of requiring one per centrifuge.

Preferably only those centrifuges lying nearest the cascade inlet are provided with perforations for vertical passage of the

tubes

30 and 31 through the

perforated plates

29 and 36. A pressure gauge is suitably introduced in the outer vessel to indicate if one or more of the centrifuges stops functioning. The reason is that a centrifuge unit which has stopped functioning gives greater pressure leakage than one which is rotating. The upper perforated plate 36 has an aperture, or perforation, 33a for each centrifuge unit C, said aperture having a diameter slightly greater than that of the centrifuge cylinder, so that the cylinder can be passed through the aperture. The magnetic bearing stator of the centrifuge unit (at 22) has greater diameter than said aperture and is firmly bolted to the upper side of the upper plate (FIG. 1). The tube or hold er 16 for the stationary inner parts of the centrifuge unit is formly bolted to the upper side of the perforated plate via the said magnet bearing stator. The driving motors 12, 13)

of the centrifuge unit, bearing casing (18) and bearing box .are attached to said lower perforated plate 29, and are removable via the aperture 29a (FIG. 1 The vertically positioned centrifuge units are suitably arranged in transverse, parallel rows (FIG. 3) in the cascade ves sel and are connected so that the centrifuge units in one and the same row process uranium hexafluoride having almost the same concentration. Collection tubes (46,47) for uranium hexafluoride (FIG. 4) having approximately the same concentration are arranged ,in parallel with said rows. The shortest of said rows on one side of the cascade vessel (11, FIG. 4) comprises one or more centrifuge units which process uranium hexafluoride of the lowest concentration and a conduit from these units leads out through the wall of the cascade vessel to the outer main conduit for depleted uranium (49, FIG. 4). The short row (1) opposite said row (1 l is connected in similar manner to the outer main conduit for enriched uranium (48 FIG. 4) and at least one of the longer rows (3 8) positioned substantially cen-, trally between said two short rows, which are diametrically opposite to each other, comprises a number of centrifugal units which are connected by pipes 45 to the outer main conduit for the supply of uranium hexafluoride having the isotope content of the starting material.

The cascade containment vessel 37 forms internally enclosed spaces above and below the horizontal perfoupper one of these spaces, above the upper plate 36, asv

shown, the water-cooling

pipes

30 and 31 being laid in contact with the plates. Thus the one containment vessel encloses everything presenting a hazard to the envi ronment. Each centrifuge has its own individual bearing system and driving motor, each forming a unit that can be installed in any.of the perforations of the perforated plates, in any grouping desiredv These perforations are formed as pairs of perforations which are axially aligned vertically and to which the rotor bearing and motors of the centrifuges are applied removably.

The invention can be varied in many ways within the scope of the following claimsv I claim:

1. An ultra centrifugal separator comprising a plurality of ultra centrifugal vertical rotors clustered together, upper and lower plates positioned above and below said rotors and forming upper and lower perforations aligned with the rotors in each instance, said rotors each having a top end piece forming a hollow extension having an open top and porjecting upwardly at least partially into the one of said upper perforations with which the rotor is aligned in each instance, bearings mounted by said upper plate and journaling said rotors via their said extensions in each instance and with their said open tops unobstructed, said rotors each having a closed bottom piece, motors mounted by said lower plate in said' lower perforations and journaling and driving said rotors in each instance via their said bottom pieces, and a single protective containment vessel for said separator and having a side wall peripherally surrounding all of said clustered rotors and a top wall covering said upper plate and forming an enclosed space above said upper plate and the open tops of said extensions.

2. The separator of claim 1 in which a pipe system positioned in said enclosed space above said upper plate interconnects said rotors via the open tops of their said extensions, for fluid transfer from one rotor to another.

3. The separator of claim 2 in which said system connects groups of said rotors for parallel operation, and connects said groups for casade operation with said groups formed by decreasing numbers of rotors in the cascading direction down to a last group having a minimum of at least one rotor, said vessel having a cylindrical side wall and said last group being formed by said system so it is next to said side wall.

4. The separator of claim 2 in which said system eonnects groups of said rotors for parallel operation, and the separator includes means for protectively separating said groups, each from adjacent groups.

5. The separator of claim 4 in which said means comprises rows of vertical tubular elements.

6. The separator of claim 1 in which said upper perforations have diameters greater than that of said rotors, and said bearings overlap said upper plates peripherally around said upper perforations and are removably fastened to said upper plate.

7. The separator of claim 1 in which said motors have flanges overlapping said lower plate peripherally around said lower perforations and are attached to said lower plate. 1

8. The separator of claim 1 in which said containment vessel has a bottom wall covering said lower plate and forming an enclosed space therebelow, and coolant pipes extend horizontally in contact with said horizontal upper and lower plates adjacently to said perforations for the extent of said rotors.

pipe system being thereby separated from said rotors by said horizontal plates and said separator in its entirety being protectively enclosed by said single containment vessel.

Claims

1. An ultra centrifugal separator comprising a plurality of ultra centrifugal vertical rotors clustered together, upper and lower plates positioned above and below said rotors and forming upper and lower perforations aligned with the rotors in each instance, said rotors each having a top end piece forming a hollow extension having an open top and porjecting upwardly at least partially into the one of said upper perforations with which the rotor is aligned in each instance, bearings mounted by said upper plate and journaling said rotors via their said extensions in each instance and with their said open tops unobstructed, said rotors each having a closed bottom piece, motors mounted by said lower plate in said lower perforations and journaling and driving said rotors in each instance via their said bottom pieces, and a single protective containment vessel for said separator and having a side wall peripherally surrounding all of said clustered rotors and a top wall covering said upper plate and forming an enclosed space above said upper plate and the open tops of said extensions.

4. The separator of claim 2 in which said system connects groups of said rotors for parallel operation, and the separator includes means for protectively separating said groups, each from adjacent groups.

7. The separator of claim 1 in which said motors have flanges overlapping said lower plate peripherally around said lower perforations and are attached to said lower plate.

9. The separator of claim 8 in which said coolant pipes are positioned on the upper and lower sides of said upper and lower plates respectively, and a pipe system is positioned in said enclosed space above said upper plate and interconnects said rotors via the open tops of their said extensions, said coolant pipes and said pipe system being thereby separated from said rotors by said horizontal plates and said separator in its entirety being protectively enclosed by said single containment vessel.