CA1107204A - Methods and apparatus for gaseous separation - Google Patents
Methods and apparatus for gaseous separationInfo
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- CA1107204A CA1107204A CA283,530A CA283530A CA1107204A CA 1107204 A CA1107204 A CA 1107204A CA 283530 A CA283530 A CA 283530A CA 1107204 A CA1107204 A CA 1107204A
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Abstract
ABSTRACT OF THE DISCLOSURE
Methods and apparatus for separation of mixtures of gaseous materials having different molecular weights, such as gaseous isotope mixtures, in which a moving surface is employed to apply an impulsive local centrifugal bending to the gas mixture laterally of the direction of motion of the surface and to produce a density gradient in the laterally accelerated gas, and in which the gas is separated in respect of the molecular weight gradient thereby produced.
Methods and apparatus for separation of mixtures of gaseous materials having different molecular weights, such as gaseous isotope mixtures, in which a moving surface is employed to apply an impulsive local centrifugal bending to the gas mixture laterally of the direction of motion of the surface and to produce a density gradient in the laterally accelerated gas, and in which the gas is separated in respect of the molecular weight gradient thereby produced.
Description
`-` ilO7Z~ -The present invention is directed to centrifugal separation, and, more particularly, is directed to methods and apparatus for centrifugal separation of mixtures of gaseous materials, such as gaseous compounds of uranium lsotope mixtures, having different molecular weights.
Isotope separation is presently a necessary process for the enrichment of fissionable fuels for most kinds of nuclear fission reactors, but consumes undesirably large am~unts of energy and requires enormous capital investm~nt in respect of process equipment and facilities. For example, conventional separation by gaseous diffusion techniques may consume about 2500 kilowatt hours per separative work unit (kwy/SWU) or more, and may require a complex and massive arxay of facilities with an amortized capital cost of, for 15~ example, over $250 per separative work unit per year.
- ~owever, the work of isotope separation has not been ~. . . .
done efficiently by conventional separation techniques and apparatus. For example, with reference to the limiting factor of the thermodynamic entropy change in respect of different molecular species, the previously referred to processing energy ratio of 2500 kwh~SWU is more than seven orders of magnit`ude larger than the energy needed for reversing the entropy incre-ment resulting from the mixing at room temperature, of the different atomic weight components of the naturally occurring i5 ~ranium isotope mixture of U235F6 and ~238F6 ~ccordingly, the potential for substantially improving separative efficiency ¦ ~8 high, and substantial research effort, governmental as well ' . .. ..
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Isotope separation is presently a necessary process for the enrichment of fissionable fuels for most kinds of nuclear fission reactors, but consumes undesirably large am~unts of energy and requires enormous capital investm~nt in respect of process equipment and facilities. For example, conventional separation by gaseous diffusion techniques may consume about 2500 kilowatt hours per separative work unit (kwy/SWU) or more, and may require a complex and massive arxay of facilities with an amortized capital cost of, for 15~ example, over $250 per separative work unit per year.
- ~owever, the work of isotope separation has not been ~. . . .
done efficiently by conventional separation techniques and apparatus. For example, with reference to the limiting factor of the thermodynamic entropy change in respect of different molecular species, the previously referred to processing energy ratio of 2500 kwh~SWU is more than seven orders of magnit`ude larger than the energy needed for reversing the entropy incre-ment resulting from the mixing at room temperature, of the different atomic weight components of the naturally occurring i5 ~ranium isotope mixture of U235F6 and ~238F6 ~ccordingly, the potential for substantially improving separative efficiency ¦ ~8 high, and substantial research effort, governmental as well ' . .. ..
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a~ industrial, has been devoted to the improvement of separa-tion systems and techniques. The largest portion of this -research effort has been directed to mechanical methods of -separation such as those employing gaseous diffusion, centzifu-gation or curved-jets.
Centrifugal separation techniques have long been ~nown ~e.g., United States Patent Nos. 1,337,774 and 1,508,405) and have found utilization in applications such as separating olids from liquids, oxygen from air, and hydrogen from oil refinery gas. Basic techniques for centrifugal separation of gaseous isotopes were developed during the Manhattan Project (e.g., United States Patent No. 2,536,423), with the development of systems utilizing a counter flow produced through application of a thermal gradient, and the provision of multiple, -coaxial moving walls, being more recent events (e.g., United - ~States Patent Nos. 2,876,949 and 3,915,673). Such centrifugal ' separation systems may employ a spinning chamber surrounded by ; ' -a vacuum, so that a mixture introduced into the center of the ', rotating chamber along its axis will tend to be separated 20 into its component parts and such that a higher molecular weight - (depleted) stream and a lower molecular weight (enriched) stream may be appropriately,withdrawn (e.g., at opposite axial ends , of the chamber~ by the dif~erential effect of centrifugal work I~ performed on components having different molecular weights.
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' I . 25 For example, in th-e case of a mixture of two gases having a- -difference of their molecular weight ~m and which is introduced along the axis of a spinning cha~ber the additional work ''. ' ' " ' ' ' ' , " : -.
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increment required to move the heavier gas component from the a~is to the chamber wall may be represented as follows:
~W = ~m~2 ~ 2 r dr = ~mQ2 r22/2 = ~m v2/2 (1) where ~W is the extra work done, r2 is the radial distance S of the moving wall of the centrifugal separation apparatus from its axis of rotation Q the constant angular rotational velocity of the apparatus, and v is vwi the speed of the moving wall VW = Qr2) However, the differential work in-crement aw done by the pressure gradient is counterbalanced by degradation due to the thermal diffusion, providing a separative factor a which may be represented as a Boltzmann factor -~ = exp ( - ~m vw2/2RT ) ~ 1 - ~m VW /2~T (2) 15. where R is the gas constant and T the temperature. The effec-tive separative factor ~ may be related to the separative factor a, as follows:
~ m VW /2RT (3) The useful work ~U is generally proportional to both the throughput L and the square of the effective separative fac-: tor ~ and for a most efficient "cut of separation" ~ at one half, the useful work may be represented: .
~U = L ~ / 4 (4) From these relationships, it is apparent that the useful work ; 25 ~U of a gas centrifuge is proportional to the fourth power ofthe wall speed vw, indicating the desirability of high wall speed, and centrifuges may have values of VW in excess of about 11~72~
400 meters per second. Furthermore, the value of can be much enhanced by the provision of an axial counterflow between the enriched and the depleted streams to cause a cascade within the spinning chamber, and a thermal gradient is generally employed in the provision o~ such a counterflow.
However, there are various disadvantages in respect of gas centrifuges. In this connection, the massive moving wall of a gas centrifuge is at the largest radial distance, resulting in a large moment of inertia which can be a dangerous feature in such processing equipment. However, the most serious drawback of conventional gas centrifuge systems are limitations on the ra'ce at which material may be processed by the equipment. Centrifugal separation of con-stituent population is pressure diffusion limited, and this 15 factor limits gas centrifuge throughput. The diffusion time ;
necessary to traverse the radial distances used to provide high wall speed (as well as the axial distance which may be about ten times the radial dimension for in situ cascade cen-trifuge) is relatively long. This constraint severely limits centrifuge throughput. At a typical capacity of about one-half SWU per day, the unit capital cost and maintenance is considerably more expensive than that of gaseous diffusion equipment, although the unit energy need has been reduced to less than 300 kwh/SWU.
In an effort to provide for increased material through-out, curved-jet systems have been developed in which the gas ., .
mixture to be separated is directed to impinge against a curved _ 5 _ ~)7204 wall, causing a centrifugal force in bending the flow of gas (e.g., U.S. Patent Nos. 2,951,554, 3,362,131, 3,708,964,
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a~ industrial, has been devoted to the improvement of separa-tion systems and techniques. The largest portion of this -research effort has been directed to mechanical methods of -separation such as those employing gaseous diffusion, centzifu-gation or curved-jets.
Centrifugal separation techniques have long been ~nown ~e.g., United States Patent Nos. 1,337,774 and 1,508,405) and have found utilization in applications such as separating olids from liquids, oxygen from air, and hydrogen from oil refinery gas. Basic techniques for centrifugal separation of gaseous isotopes were developed during the Manhattan Project (e.g., United States Patent No. 2,536,423), with the development of systems utilizing a counter flow produced through application of a thermal gradient, and the provision of multiple, -coaxial moving walls, being more recent events (e.g., United - ~States Patent Nos. 2,876,949 and 3,915,673). Such centrifugal ' separation systems may employ a spinning chamber surrounded by ; ' -a vacuum, so that a mixture introduced into the center of the ', rotating chamber along its axis will tend to be separated 20 into its component parts and such that a higher molecular weight - (depleted) stream and a lower molecular weight (enriched) stream may be appropriately,withdrawn (e.g., at opposite axial ends , of the chamber~ by the dif~erential effect of centrifugal work I~ performed on components having different molecular weights.
.. . . .
' I . 25 For example, in th-e case of a mixture of two gases having a- -difference of their molecular weight ~m and which is introduced along the axis of a spinning cha~ber the additional work ''. ' ' " ' ' ' ' , " : -.
,`' '' . ' ', , ' ' ' " -3-' ' ' ' ~' , .'. , ,' , , .
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increment required to move the heavier gas component from the a~is to the chamber wall may be represented as follows:
~W = ~m~2 ~ 2 r dr = ~mQ2 r22/2 = ~m v2/2 (1) where ~W is the extra work done, r2 is the radial distance S of the moving wall of the centrifugal separation apparatus from its axis of rotation Q the constant angular rotational velocity of the apparatus, and v is vwi the speed of the moving wall VW = Qr2) However, the differential work in-crement aw done by the pressure gradient is counterbalanced by degradation due to the thermal diffusion, providing a separative factor a which may be represented as a Boltzmann factor -~ = exp ( - ~m vw2/2RT ) ~ 1 - ~m VW /2~T (2) 15. where R is the gas constant and T the temperature. The effec-tive separative factor ~ may be related to the separative factor a, as follows:
~ m VW /2RT (3) The useful work ~U is generally proportional to both the throughput L and the square of the effective separative fac-: tor ~ and for a most efficient "cut of separation" ~ at one half, the useful work may be represented: .
~U = L ~ / 4 (4) From these relationships, it is apparent that the useful work ; 25 ~U of a gas centrifuge is proportional to the fourth power ofthe wall speed vw, indicating the desirability of high wall speed, and centrifuges may have values of VW in excess of about 11~72~
400 meters per second. Furthermore, the value of can be much enhanced by the provision of an axial counterflow between the enriched and the depleted streams to cause a cascade within the spinning chamber, and a thermal gradient is generally employed in the provision o~ such a counterflow.
However, there are various disadvantages in respect of gas centrifuges. In this connection, the massive moving wall of a gas centrifuge is at the largest radial distance, resulting in a large moment of inertia which can be a dangerous feature in such processing equipment. However, the most serious drawback of conventional gas centrifuge systems are limitations on the ra'ce at which material may be processed by the equipment. Centrifugal separation of con-stituent population is pressure diffusion limited, and this 15 factor limits gas centrifuge throughput. The diffusion time ;
necessary to traverse the radial distances used to provide high wall speed (as well as the axial distance which may be about ten times the radial dimension for in situ cascade cen-trifuge) is relatively long. This constraint severely limits centrifuge throughput. At a typical capacity of about one-half SWU per day, the unit capital cost and maintenance is considerably more expensive than that of gaseous diffusion equipment, although the unit energy need has been reduced to less than 300 kwh/SWU.
In an effort to provide for increased material through-out, curved-jet systems have been developed in which the gas ., .
mixture to be separated is directed to impinge against a curved _ 5 _ ~)7204 wall, causing a centrifugal force in bending the flow of gas (e.g., U.S. Patent Nos. 2,951,554, 3,362,131, 3,708,964,
3,853,528 and 3,877,892). A portion of the gas stream repre-senting a higher molecular weight cut (head assay) may be subsequently diverted ~y a knife-eage, or ~skimmern, from the gas stream immediately adjacent the curved wall representing a higher molecular weight cut ~"tail assay") and the resulting ~ead assay and tail assay streams are subjected to subsequent .
curved~jet separation treatment in a counterflow cascade system to cumulate the incremental separative effect of each curved-jet passage of the gas.
In such curved-jet systems, pressure energy of the gas is converted into curved flow energy with a curved convergent-divergent nozzle, and a carrier fluid with a very low molecular weight is employed to give the high molecular weight gas a high flow velocity. Since the throughput L of equation (4), supra, is also proportional to the flow velocity, vf, and the square ~f the effective separative factor ~ is proportional to Vf4 , the useful separative work ~U becomes proportional to v~5 .
~0 Furthermore, the difference of molecular weight of an isotope -- mixture also gives rise to a difference of sedimentation time in a low molecular weight carrier fluid. Therefore, in a high centrifugal field, this difference of sedimentation time may be used to obtain a i~lightly higher separative factor ~ than I 25 that of the corresponding equilibrium value of a centrifuge.
I The diffusion time of curved-jet systems may be optimally selected by pro~iding the curved wall with a prede-¦ termined relatively small length in a direction along the gas , ~ . . . ' :~
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` ~1072~4 , . . . : , tra~ectory, while providing for system throughput'by making . ' the no~zle and wall relatively long in a direction orthogonal ' to the gas trajectory. -However, a major portion of the pumping energy in curved-jet uranium isotope separation is S wasted in processing the low molecular weight carrier fluid, - and the pumping energy and displaced momentum are generally ' not recoverable. The separation of the carrier fluid also requires some work. These considerations push the overall energy needs to a high level of about 4000 kilowatt hours per separative work unit, making 'the c~rved-jet method un-attractive without an order of magnitude reduction of its energy consumption. In order to partially alleviate this problem, it is possible to combine and carry out th'e pumping and carrier fluid separation in one rotating chamber to~save ; 15 a fraction of the energy requirement, thereby reducing the energy requirement to a reported value of about 3500 kilowatt Xours per separative work unit. ~owever, this level of energy oonsumption per SWU is sti}l undesirably high.
'' ' ' ~t w~ll be appreciated that basic principles of mechanical systems of separation, such as gaseous diffusion, centrifugation and curved-jet separation are in genër'al' terms conceptually relatively simple, and the estimation of the ' efficiency of such systems i9 relatively straight forward ' (although the achievement of such efficiency in actual practice 2'5 may involve substantial technology). However, given the design of such a system, it i8 difficult to provide drastic'improve-I ment in performance within the constraint of the particuiar ¦ '' '' design . . . ,., - , .
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~ ccoraingly, it is an object of the present inven-tion to provide new methods and apparatus for the molecular weight separation of gases. It is a further object to provide such methods and apparatus having improved efficiency and/or throughput characteristics. These and other objects of the invention will ~ecome apparent in view of the following de-tailed description and the accompanying drawings, of which FIGURE 1 is a perspective view, partially broken away, of an embodiment of turboseparative appratus particu-larly adapted for operation at subsonic speeds;
FIGURE 2 is a schematic side view of the embodi-ment of FIGURE 1 taken through line 2-2;
FIGURE 3 is a schematic top view taken through line 3-3, illustrating blade and gas supply features of the embodiment of FIGURE l;
FIGURE 4 is a schematic illustration of another embodiment of blade and gas supply design suitable for use in apparatus like that of FIGURE l;
FIGURE 5 is a perspective view, partially broken away, of apparatus adapted for gas separation at supersonic speeds;
FIGUXE 6 is a partial axial side view of the apparatus of FIGURE 5 taken through line 6-6;
FIGURE 7 is a partial cross-sectional front view of the rotor and stator assembly of FIGURE 6 taken through line 7-7;
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FIGURE 8 iq an illustration of another embodiment - of ~tator and rotor configuration suitable for use in connec-tion with apparatus like that of FIGURE 5: - -FIGURE 9 is a partial side view of the apparatus S of FIGURE 8 taken through line 9-9;
FIGURE 10 is a partial schematic side view of ~nother embodiment of separative apparatus, and FI~URE 11 is a side view of the apparatus of FIGURE
- lb taken through line 11-11.
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Generally in accordance with *he method of the present invention, a gas mixture to be separated in respect of its diferent molecular weight components is provided in A sepa~ation zone, and a moving surface is forced through - the gas in the separation zone to impart an impulsive type of centrifugal bending", or acceleration of the gas lateraliy o~ the direction o movement of the moving surface.
Th~ lateral àcceleration may pro_uce a molecular weight density gradient in the gas accelerated by the moving _ surace, with maximum density at the moving surface and with ; io decrea ing density as a function of lateral distance from the surface. A higher molecular weight portion of the gaa Imme-d$ately adjac~nt^the surface may then be separated from lower molecular weight gas. The gas portions of differing molecular ; - weight obtained in this manner may be each subsequently sub-~ 25 jected to separation treatment to produce a high degree of I separation o the components of the gas.
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The method is pa~ticularly adapted for use in the enrichment of uranium compounds in the u235 isotope, and in ' this connection, the gaseous uranium hexafluoride compound is conventionally used for enrichment purposes. However, methods S and apparatus in accordance with the invention may also be ~ used in the separation of other isotope mistures ~e.g., radio-,isotope separation or enrichment) and in the direct separation of gaseous mixtures of different elements or compounds (e.g., , separation of the component gases of air).
! lo The solid surface forced into the gas mixture is desirably a curved surface having a surface curvature such that a relatively uniform centrifugal field may be provided along at least a portion of the curved surface as the surface is forced ~ into the gas mixture. : -- 15 ' ~hrough the step of forcing a curvea surface through ' a zone containing the gas mixture, a high relative velocity may '~ ' , be maintained between the gas and the moving surface, and this may be accomplished without the use of a carrier fluid when the gas components to be separated have high molecular weight.
Furthermore, the motion of the curved surface is desirably rota-, , .
- , tional motion, which may produce centrifugal or axial pumping , energy in the separation process which may be recycled or otherwise utilized without substantially disturbing the effect-.
, .iveness of separation. Moreover, the laterally accelerated gas may be subsequently deaccelerated, in a direction opposite that of its original acceleration, by mea~s of a suitably positioned ' surface in order to recover a portion of the energy expended ' in the original acceleration of the gas.
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Apparatus in accordance with the present invéntion generally comprises means for confining a gas mixture in a .
separation zone, a plurality of blade means each defining at least one curved surface for laterally accelerating gas L 5 upon motion therethrough, ~eans for moving the blade means in the separation zone to produce a density gradient in the gas adjacent the curved surface of the blade means. The apparatus generally further comprises means for separating the gas with respect to the density gradient produced by blade motion.
Desirably, the blade means will be rotatably mounted so that the curved blade eiements may be rotatably forced to intercept the gas mixture, and the apparatus may further in-clude means for recovering the kinetic energy of the gas laterally accelerated and/or centrifugally pumped by the ~oving blade elements. Furthermore, a plurality of such turbo-ceparative elements may be appropriately connected in a cascade manner ~o provide for cumulation of separation.
Turning now to the drawings, the present invention will now be more particularly described with respect to the embodiments of apparatus shown in FIGURES l-~.
Illustrated in FIGURE 1 is turboseparative apparatus ; , lO which is particularly adapted for subsonic operation. The illustration of the apparatus 10 is broken away to display ,a separation zone 12 defined by the end bulkhead 14, casing elements 16 and 18, and gas supply disk 20. The separation ~one is hermetically sealed with the exception of gas entrance . 'I .
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and exit supply means, which wi11 be discussed in more detail hereinafter. The apparatus further includes a rotor element 22 which is rotatably mounted on driveshaft 24.
~he rotor element 22 comprises a portion of a conical inner drum 26, a cylindrical outer shroud ring 28, and a plurality of hollo~ blades 30 which are regularly spaced about the rotor element 22. The entire rotor assembly is radially symmetrical with respect to the axis of the driveshaft 24, and is adapted to be rotated in a clockwise direction in respect of the view of the drawing as i~dicated by the arrow at the driveshaft-bulkhead bearing 24. The blades 30 of the rotor element are generally of airfoil shape de-signed to minimize turbulence, and in the illustrated embodi-ment.are oriented so that a "sharp" edge of the airfoil is ; 15 the leading edge in the direction of blade motion throughthe separation zone 12. Each of the blades 30 has a curved ~urface 32 for laterally accelerating the gas upon rotation of the rotor element.
Also contained within the separation zone 12 and adjacent the first rotor element 22 is a second rotor element 34 comprising a second set o~ blades 36 which are similarly mounted on the conical drum 26 and surrounded by a cylindrical shroud ring 38. The blades 36 of the second . rotor element 34 are also of a hollow airfoil design to : 25 minimize turbulence, and are mounted at their root ends in regular array on drum 26 adjacent blades 10, but in the illustrated embodiment have an orientation opposite that of ~ 12-.
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the blades 30 of the rotor element 22 so that the "blunt"
edges of the blades 36 are the leading surfaces in the di-rection of blade motion. Like rotor element 22, rotor element 34 is radially symmetrical about the axis of the drum 26 and driveshaft 24, and its blades 36 terminate at their peripheral tip end in attachment with a cylindrical ring shroud 42.
The ring shrouds 28, 42 define the outer bound--~ ary of their respective rotor elements 22, 34, and in turn define the inner boundary of centrifugal pump diffuser and collector zones 44, 46 surrounding the respective rotor elements. In this connection, the shroud rings form a ro-tating seal with seal element 46 of their respective casings 16, 18 to prevent passage of gas from the separation zone 12 ' into the diffuser and collector zones 44, 46, with the excep-; 15 tion of gas from the interior of the blades 30, 36. The second set of blades 36 is positioned to intercept and re-cover momentum from gas deflected by the first set of blades and both sets of blades are provided with means for admittlng gas to the blade interior, as will be discussed in more detail hereinafter in connection with FIGURE 2.
As indicated, each'of the blades,30 and 36 is , . hollow, being provided with radial passageways 38, 40 ,, longltudinally of the airfoil cross-section. While the blades ~0, 36 are substantially closed adjacent the drum 26, the , 25 passageways 38, 40 of blades 30j 36 each communicate respect-;, ively ~ith diffusion and collection zones 44, 46 by means of , paEsageways 48, 50 provided through shroud'rings 28, 36 for - ,' th~s purpose.
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~O~ )4 Gas may be conducted from each diffuser and - collector zone by means of a suitable conduit, as a product discharge, or ~or appropriate reintroduction in a cascade manner into another separation zone. In the illustrated S embodiment, a conduit 52 is employed to conduct gas from the diffusion and collection zone 46 to the manifold 54 of the input disk 20 which serves an adjacent separation zone.
While direct conduction of gas from zone 46 to manifold 54 is shown for convenience, the gas may advantageously undergo intermediate processing steps such as cooling and enersy recovery steps, a.s will be discussed in connection with FIGURE 2.
The manifold 54 of the supply disk 20 surrounds a plurality of radial feed tubes 56 which are regularly spaced about the axis of the drum 26 and through which input gas is supplied to a separation zone adjacent zone 12.
Separation zone 12 itself is supplied with input . gas by means of a manifold 62 which in turn supplies a plural- ~ :
ity of radially symmetrical and radially projecting feed tubes 2Q. 56. An adjacent zone is supplied by manifold 54. The manifolds 62 and 54 may be supplied by suitable supply conduits ~not shown in FIGURE 1) from the desired gas source of appropriate cascadc staging. It is noted t.hat the disk element 20 i5 . po~itloned between two adjacent separation.zones and serves ' ' , ... . . .
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each zone through independent manifolds 54, 62 and their respective supply tubes, while the bulkhead disk 14 is at the end o~ apparatus 10 and need only serve separation zone 12.
Turning now to'FIGURE 3, the operation of the S' separation zones of the apparatus 12 will now be described with reference to the simplified schematic representation of a separation zone 100 there shown in schematic top view bounded by two.stationary supply disks 102, 104 and radially tow~rd the axis at one pair of deflection blades 30', 36'.
The direction of rotation of the blades is toward the right as-shown by arrow, and gas to be subjected to treatment in the-separation zone 100 is introduced int.o the zone by means of feed tubes 106, 108 supplied by their respective manifolds . . . ..
,(not shown). The feed tubes are longitudinally hollow and 15'' have a longitudinal convergent-divergent slot nozzle 110, 112 adapted to provide efficient discharye in a direction opposite .~ .
' the direction of motion of the blades 30', 36' and minimization , of discharge turbulence. The blades themselves are hollow, and are each respectively provided with a longitudinal opening 108, 110 extending substantially the radial length of the blade ' ~or accepting gas from the zone 100 into the hollow interior o,f the,blade. The 4irst blade 30' has a sharp edge 112 of its a~rfoil configuration oriented as the leading edge with an , angle of attack approximately equal to the flow streamline of , 25 the gas, which in the illustrated embodiment results in an attack vector approximately parallel to that of the direction , of motion of the blade 30'. The blade 30 has a surface 118 ," ,, '.' ' . . ' " ' ' ~
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tra~ling the leading edge 112 which has a positivé curvature in the direction of the top of the drawing. The curvature of the surface 118 provides for lateral displacement of the gas in the direction of curvature upon rotational motion of the bladè, and in this connection is designed in accordance - - with aerodynamic principles to subject gas forced over the surface 118 by motion of the bladç to an impulse accelerative field under streamline (non-turbulent) flow conditions. Under these conditions, higher molecular weight components of the gas tend to preferentially move toward the curved surface 118 and lighter components tend to preferentially move away from the surface, producing a density gradient in the direction of ...... ... . .
;-~ the applied impulse field upon passage along the curved surface 118. Subsequently, at blade slot 114, a denser ~raction adjacent the curved surface may be diverted to the interior of the blade 30 by a slot knife edge, or ski~mer means 120 projecting in a predetermined manner into the streamline flow from the surface 118. The fraction of the flow diverted to the interior of the blade will depend on a number of factors such as the blade speed, blade~dimensions, blade curvature, ~ skimmer position and opening width, surface smoothness, and ga~ mixture density.
As indicated, lighter components of the gas tend to be relatively displaced away from the curved surface 118 upon passage thereover, and a portion of this lighter fraction may be diverted into the interior of the sscond blade 36' through blade intake slot 116 which is appropriately positionFd to ' ~ ' ' .1 , . . . .
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I :16-~, ~l~qZ04 lntercept a portion of the lighter density flow stream under operating conditions. The remainder of the gas, which has been given a velocity component orthogonal to the direction of blade motion primarily through application of impulse forces ~as well as a velocity component in the direction of - ~lade motion through drag and impulse forces) is directed to intercept surface 122 of blade 36' which has a countercurvature to recover as a rotational force the lateral gas momentum imparted by the curved surface 11~.
The heavier gas portion diverted to the interior of the blade 30' will be expelled from the blade through its shroud passageway into the respective diffuser and collector .--zone in the manner of a centrifugal pump, and may be conducted . . therefrom as a product stream or for reintroduction to another . 15 separation zone operating on higher density fraction gas.
Similarly, the lighter gas fraction diverted to the interior . of the blade 36' will be centrifugally pumped from the zone and may form a product stream or a source stream for another -~ separation zone adapted to process a lighter gas fraction. ...... ,...... . :
As indicated, processing may be cascaded by means ~~ of a plurality of separation zone units a~d such cascading is generally conventional in the separation of mixtures of high ~olecular weight materials with a small molecular weight difference such as ~F6 isotope mixtures. In this connection, the turboseparative apparatus 10 of FIGURE 1 comprises a plurality of axially stacked separative units 201, 203, 205, 207, 209 which are schematically illustrated in side view by ~; ' ' ' I ' . .. .' : . !
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- FIGURE 2. In FIGURE 2, the apparatus 10 is shown as comprising .
a plurality o aiternatingly adjacent rotor element pairs 204, ~06~ 208, 210, 212 and stationary feed disk elements 214, 216, 218, 220 each having appropriate manifolding and feed tubes for S separately feeding each side of each disk. The separation units 201-209 are respectively made up of one rotor element pair and the adjacent feed side of each adjacent feed disk.
~he rotor pairs may be mounted on a common drum 26', and each stationary disk element forms an effective rotating seal with the drum 26' to prevent unintended flow ~etween separation unit sections.
In operation, an input feed mixture 240 to be subjected to separation treatment may be conducted by conduit means 242, 244 to the respective feed tubes 246, 248 for the separation zone oontaining the central rotator blade pair 250.
The heavier gas component stream 254 diverted and pumped by . the first blade set 252 of the rotor 250 is supplied as the input stream for feed tubes 256 of disk 218 of another ~adjacent) separative unit, while the lighter gas component forced into and pumped by the countercurved blade se~ 258 is supplied as an input stream to the feed tube 260 of another separative unit. The lighter and heavier components of each separative unit are similarly fed respectively, in cascade manner, to lighter and heavier separative unit processing stages ~in terms of component gas mixture being processed) a~ shown in FIGURE 2, with the heaviest gas product stream being withdrawn from the blade set of the l~st "heavy gas"
stage, and the lig~test gas product strea~ being withdrawn from the light fraction blade set of the last ~light gas~ -~ 30 stage of the cascaded system. In the schematic illustration : . .
.
I ..
.
of ~IGURE 3, with the indicated blade orientation, gas feed configuration and rotational direction, the light fraction head output stream 280 o~ blade set 204 represents the lowest ~olecular weight output stream illustrated, and the density S of gas processed by each separative unit increases with increasing reference numeral from separation zone 201 to zone 209, where the high molecular weight tail stream from , blade set 214 represents the lowest molecular weight output -stream illustrated. Of course, additional separative units might be provided in cascade manner axially of those illustrated.
The gas centrifugally pumped by the respective blade sets may be subjected to various processing steps before reintroduction into the system, and such processing is indicated schematically in FIGUR~ 2 by processing blocks 270.
In particular, it may be desirable to cool the gas to a pre-determin~ed temperature before recycle into the system, and such cooling may be accomplished by conventional heat exchange apparatus and techniques. It may also be desirable to recover energy from the centrifugally pumped stxeam and for this purpose a suitable turbine, preferably connected directly to ,;,"..
the drives}taft or drum of apparatus 10, may be employed. It is noted that cooling, if any, will desirably follow any energy recovery step, and that integrity of the respective streams should be maintained without mixing with other streams oE different molecular weigbt distribution in respect of the components to be separated.
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In connection with the general operational per~
formance parameters of apparatus such as illustrated in FIGURES 1-3, it may be considered from Equations 1-3 that the separative constant generally depends upon an altered velocity of the gas while the gas i5 laterally displaced, or "bent". The altered velocity of the illustrated apparatus 10 is approximately the cutting speed of the blades through the gas in a separation zone where the gas is kept relatively stationary while being accelerated laterally by means of cur~ed surfaces forced through the gas at high speed. The first set of curved surfaces, or blades, have openings at their trailing edges to scoop away a portion of the higher molecular weight tail stream ("depleted" stream in uranium isotope separation). A second set of curved surfaces co-moving with the first, and having a countercurvature to recover some of the laterally altered momentum is also provided with i openings at the leading edges to take in a portion of the lighter molecular weight stream ("enriched" stream in uranium isotope separation). There are many pairs of appropriately positioned hollowed blades arranged in the form of a rotor element similar in some respects to those of a turbine. Gas, once scooped into a hollowed blade, or the intake tube, will be swung to the blade tip, and exits from the rotating disc, converting kinetic energy into pressure. There are also -~5 stationary walls in the form of discs intervening between the rotor discs, and feed gas swung and pressured from the rotation of the preceding disc enters a separative disc-chamber through 7Z~ -feed tubes in the stationary disk wall. The feed tubes and wall structure separating th~ blade ch2mbers may also serve to retard the co-rotational tendency of the gas. In this connection, the retarding effect of the wall structure may be enhanced, such as by providing projections lS0 and by ~ ~ directing feed gas axially into the blade chamber rather than ; in the direction of blade rotation as shown by feed tube embodiment 152 of FIGURE 3. Moreover, the co-rotational tendency may also be counteracted by having the gas discharge 10 from the feed tubes in a direction opposite the direction of blade rotation as shown in FIGURE 3 by feed tube elements 154, 156, although it will be appreciated that the input pressure should exceed the static pressure head from any rotational velocity of the gas at the points of introduction. The 15 mihimum input pressure may be reduced by partially shielding the input noz~le, by limiting the points of input to inner radial positions where any co-rotational velocity would be lower, etc. A co-rotating drum forms the base for the inner rotational structure or central portion of the turboseparative 20 apparatus where the speed is low, and, as indicated, excess centrifugal feeding pressure may be used to accelerate the ~ .
drum The radial dimensions of the drum may be adjusted to - match the input-output specifications of the various flows in - ~ respect of different units of the cascade system. The gas 25 mixture to be processed may be main~ained at a temperature su~table to provide an appropriate vapor pressure, which may be in the case of UF6, for example, about two Atmospheres.
, The frictional energy dissipated in each disc-chamber will generally be sufficient to keep a higher molecular weight ¦ 30 gas such as UF6 at a desired elevated temperature, and excess . ~
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'~ ' : : :
1~7;~0 ., . ' heat may be removed ~hrough the co-rstating drum, the casing, and/or from the process gas streams as indicated previously.
In estimating and discussin~ the processing capacity and unit energy requirement for apparatus of the type illus-S trated in FIGURES 1-3, an exa~.ple of moderate design values may be considered. In the case of turboseparative apparatus ~bout one meter in diameter moving at a peripheral speed of about 500 meteis per second, the cutting speed of the blades may range from about 500 to about 300 m~s, with an average spesd of about 400 meters per second. In such an apparatus having nine cascaded separation chambers and operated with UF6 at a pressure of two Atmospheres there are about 0.01 grams of U238 per cc. If the input velocity of the feed st~eam through the tubes having a cross-sectional area of abollt 20 square centimeters is about 200 meters per second, a throughput of about 4 kilograms per second may be provided.
An effective separative factor for each separation unit or chamber may be, using the equilibrium centrifugal value:
~i = Am v / 2 R T = 0.046 ~5) ~ The capacity per separative unit stage may be:
~Ui = ~ ~i / 4 - 2.12 gts - 6.65 x 10 kg SWU/a (6) . For the nine-stage turboseparative processing unit , 2 under consideration, the useful work may be:
0.60 ~illion SWU~a . ~7) , : ..
j The energy re~uirement may be considered as:-. ~ 2 E c L x ~v ~2) x fl x f2 x number of separative units ~ - t8) i ~ . ..
, -22-~ ... ... .... , ~ .. . ...... ... ... .. . .
.
, , : :
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.
~1~7Z04 where fl is the frictional drag of the blade ~a function of the bending angle and its surface smoothness) and f2 is the feedback factor where the pressured gas provided by rotational motion of the blades is reused to accelerate the drum. Flux (gas portion) scooped away is considered as part - of the drag. The factor fl x f2 may, for example, approximate 1/5, and for a separative unit system, E may be estimated at about 580 kilowatts. Since the unit energy requirement is representable by the factor E/~U, the unit energy requirement lC may be estimated as follows:
unit energy requirement = E/~U = 8.4 kwh/SWU ~9) The indicated flux through the tubes may be higher, the factors fl and f2 being dependent upon design factors.
Moreover, it is noted that such a relatively small turbo-separative processing unit may be capa ~e of processing on the order of about one million S~ annually, with a unit energy requirement which may be less than 1% of the current value by diffusion of 2500 kwh/SWU.
The unit energy requirement may also be considered - by comparison with the requirements of conventional processing techniques. In the curved-jet method, conventionally only one part in ten of the pumping energy directly pumps on the seed gas, and by processing without the use of a carrier fluid, the energy requirement may be reduced by an order of magnîtude.
I ~ *~dditional energy saving also results from not having to ! separate the seed gas from the carrier gas. The rotary blade . . -- - : .
~'~ . ' .' ' ' - ' ,. . '' . ,__ . ...
. ~ ' elements form part of a centrifugal pump, and part of the ~inetic energy gained is recoverable as pressure energy of the feed gas by directing it to accelerate the rotating drum.
lf all these considerations combine to a factor of five, the '5 conventional curved-jet energy requirement of, say, - 4000 kwh/S~ may be reduced by a factor of a~out fifty.
Moreover, while the internal fric~ional heat generation of the nine unit turboseparative apparatus case previously considered may be conservatively estimated at about 100 kilo-watts per unit, this value is probably excessive and could be substantially reduced by appropriate design considerations intended to reduce turbulenf~e and other frictional losses.
Accordingly, a reduction of energy requirement by a'factor of, say, one hundred, both in capital cost and in energy consumption, would appear to be appropriate to the turbo-separative apparatus.
: - Contxol of degrading turbulence in the separation chamber is very important in order to produce a predicted and - desired value of separative factor ~. In this connection, the axial dimension of the chamber may be made large to permit - turbulence to decay. The dimension of the hollowed ~Iades may be made small so that the fluid dynamics operations performed by the blades are at a scale smaller than the scale of the ' turbulence of the gas in the blade chamber. In this'latter connection, it is noted that the blades and curved surface dimensions may be substantially smaller'than indïcated in the drawings for purposes of illustration, and for uranium isotope 11 ' ' ' ' "
- .
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separation the blades and curved surfaces may be quite small and the skimmer cut thickness may be on the order of magnitude of the shock wave thickness. In addition, the bladie pairs may be brokan up, with one turbine blaae set processing the S head stream, and the other oountercurved turbine blade set processing the tail stream, with the two turbine sets feeding each other to form a processing unit, although this variation has the disadvantage of not providing for opposite curvature blade momentum recovery.
Since the higher molecular weight tail assay may be scooped away at the trailing edge of a blade, this function i8 less susceptible to the degrading effect of turbulence, and the two sets of blades, one curved and the other counter-curved, may both be of the type which divert the high molecular weight fraction. The low molecular weight fraction may be permitted to travel or ~leak through" in a suitably controlled manner along the axial direction by providing an appropriate stationary disc element. Further in this connection, the axial velocity of the gas imparted by appropxiate rotor elements may be converted to pressure énergy and utilized in the system.
Another variation providing for higher throughput comprises two sets of blade pairs in one separation chamber which are adapted to rotate in opposite directions, thereby countering the co-rotational motion tenden~y of the gas while utilizing the rotationally induced velocity components to separative function advantage. The oppositely rotating rotor . i ...................... .
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blades may ~oth be of the type having means for generating a centripetal field and means for separating a heavier fraction, such as the s~immer means whic~ scoop away the higher molecular weight tail assay and feed it back to a S preceding higher molecular weight separation unit chamber, while the lighter head assay is permitted to travel along the axis to succeeding lower molecular weight separation unit chambers, in a processing direction opposite to that of the tail assay stream. Appropriate mechanisms to turn the blade sets in opposite directions may be housed along the axis within segmented drum sections.
Other variations of blade configurations particularly adapted for subsonic turboseparative methods and apparatus are illustrated schematically in FIGURE 4 of the drawings, which - 15 is a partial schematic side view of two rotor elements 302, 304 and two stator elements 306, 308 stacked along an axis 310 of radial symmetry. Rotor elements 306 are adapted to turn about axi8 310 in the direction of the indicated arrows, and it is to be understood that there may be additional rotor and stator , elements stacked along the axis 310 "above" and "below" those illustrated. The rotor elements 302, 304 have a plurality of s regularly spaced blades 318 for laterally accelerating gas, and the stator elements 306, 308 have a plurality of regularly spaced redirectional blades 314, 324 for redirecting gas impelled by the rotor blades 318 with a force vector in a direction opposite the rotational direction of the blades 318.
A gas mixture to be subjected to separative treatment may be '.' ..'' ,,. .
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.
11'~7Z~)4 introduced into the system by means of longitudinally placed nozzle elements 312 of the impulse-curved redirectional blades 314 by means of suitable manifolding and supply means such as that illustrated in FIGURES 1 and 3. The gas discharged by the nozzle elements 312, which may be of isentropic expansion - type to provide minimization of discharge turbulence and maximum efficiency in conversion of feed pressure to gas velocity,is directed at an angle with respect to the axis 310 ~hich provides a discharge velocity component opposite the directional rotation vector of the rotor elements and which may qenerally coincide with the impulse-redirected discharge angle provided by the curvature of the blades 314 in respect of gas originating from the next lower rotor element (not shown). This gas discharge direction and redirected gas direction from the stator blades 314 also may correspond .. . .
generally to the operational angle of attack of the blades 318 of rotor element 302, which are of the hollow "scoop" higher molecular weight separative type and which have curved surfaces 320 for laterally accelerating the gas and longitu-dinal openings 319 bounded by knife edges 321 which divert ~ internally of the blades a portion of the gas representing a higher molecular fraction. The diverted gas is centrifugally pumped by the blades to a diffuser-collector zone such as shown in FIGURE 1 to a preceding higher molecular weight stage ~i.e., a lower stage in tbe illustration), and may be previously cooled or extracted of its pressure energy. The gas vhich is not so diverted has been provided with a velocity ;. j ' , " ' . I ' . `
-27;
:
1~7Z04 component in the direction of the axis of the turboseparative apparatus, and a velocity component in the direction of blade rotation. This gas is directed to stator element 306 which has curved blades 314 with an inlet angle generally co~responding to the velocity vector of this remaining lighter gas fraction which has pass~d through rotor element 302. The impulse redirectional blades 324, like ~lades 314 of the preceding stator element, redirect the flow of lighter fraction gas from the preceding rotor element and provide for reintroduction of a heavier fraction from a succeeding rotor element ~not shown) in a direction appropriate for intercep-tion by succeeding rotor element 304. It will be appreciated that a plurality of alternating rotor and stator elements may ~e provided and connected in a cascade manner, and that the - 15 input feed gas to the resulting cascade system may be fed to an axially centrally located stator element. Upon introduction ; ~f-a gas mixture to an intermediate separative section, a final process heavy fraction may then be recovered from the upstream - end rotor element, for example, and a final process light fr~ction may be recovered as an axial discharge stream from the other end of the stacked turboseparative system.
Of course, many design variations are possible in resp~ct to the present invention, and several variations are shown in the upper right section of FIGURE 4 separated by dashed line 330. In the illustrated variation, the "scoop"
blade 334 does not have a knife-edse or s~immer defined opening, but instead is provided with a perm~able zone 332 '. ~ ' ' ~
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.
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along the curved surface. The zone 332, which is of a smooth, but microporous nature, permits passage of heavier gas there-~hrough from immediately adjacent the surface, but does not have a macroscopically rough surface which would generate excessively turbulent flow. The stator blade 336 may also be provided with means to separate and ~onduct therefrom a gas fraction, such as a knife-edge or skimmer defined opening, or a permeable ~one 338 As indicated, turboseparative apparatus of the type illustrated in FIGURES 1-4 may be particularly adapted for operation at speeds which are grossly subsonic with respect to the gas mixture to be separated, but which may be locally supersonic with respect to components of the mixture. In this connection, it is noted that sonic velocities decrease as a function of molecular weight, thereby decreasing the - xotational velocity which may be utilized before supersonic ~peeds are reached.- However, a~ligXter molecular weight gas, suoh as hydrogen, may be mixed with a heavier gas, such as UF6, to provide for increased7b~a~e velocity, and systems in w~ich the lighter fraction travels axially of the rotor ; elements are particularly adapted for such gas mixtures. The - lighter gas-"lubricant" may be readily separated from the ~inal light product stream and need not be separated at each :;
:: separative stage.
~5 It is-also desirable to provide methods and apparatus which may be particularly adapted for use at supersonic speeds, slnce various separative factorF are a function of operating ~' ~', . ' .
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.
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1~7204 speed. In a turboseparative unit, the highest speeds are prov~ded at the periphery of the rotating elements, and separative blade elements may be provided which are particularly adapted to be used at supersonic peripheral rotational speeds in respect of the gas mixture to be processed.
Illustrated in FIGURE 5 is a perspective view partially broken away of supersonic turboseparative apparatus 500 which comprises a plurality of axially stacked separative units internally of casing 502 supplied by gas manifold supply means 501, 503, 505. The separative units are shown in more detail in FIGURES 6 and 7 and comprise rotor means 507 having a plurality of deflector blade elements like element 602 regularly mounted in a radially symmetrical manner about the periphery of a rotating disc 504. Adjacent the deflector blade elements is a gas distribution ring which is employed to distribute gas to be processed into the path of the deflector blade units including units 601, 60 , 603. The ~` deflector blade units themselves are provided with curved surface bounded passageways which provide for lateral displace-ment of the gas at high velocity, and the consequent production of an impulse acceleration field ~in the illustrated embodiment, a number of such fields are produced) to provide a density gradient (several gradients in the illustrated embodiment) , 25 g~nerally in the direction of the field(s). The separative units also have means for dividing the gas in respect of its I density gradient(s) into fractions of different molecular ¦ weight.
'. , . , ..
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-3Q- _ 11~7~04 In the apparatus 500, a relatively stationary qas mixture may be provided in a disc-chamber zone 605 defined by stationary disc walls 730, 732 which form a seal with shroud rings 604, 606 and which have means such as a perforated ring 607 to provide for feed gas entry. A
plurality of processing deflector blades may be rotatably mounted to rotate at supersonic speed into the path of admitted feed gas with a speed v~ = r2Q, where r2 is the radial distance of the blades from the axis of rotation; and o n is the rotational velocity. Because o~ the lateral curvature of the passageways of the deflector blades, feed gas which is intercepted by the deflector blades may be forced, or bent, laterally of the direction of rotation ~e.g., in a radial direction or in a direction parallel to the axis of rotation, or in a direction having both radial and axial components) to have a radial and/or axial speed vz or vr approximately that of v~ (e.g., v~ ~+v~) and bent, or accelerated, again in a generally opposite direction to substantially recover the lateral velocity component. During each bending, a por~ion of the higher molecular weight assay may be subtracted from - - the stream and fed in a cascade manner as input feed gas to another disc-chamber operating on a higher molecular weight mixture ~one stage up). The resultant lighter stream having the higher molecular weight cuts deleted therefrom may be ?s similarly fed to another disc-chamber operating on a lower molecular weight mixture (or.e stage down). The segregated heavier fractions may exit the deflector at high velocity, ' . 'I ' ' ', .
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11~7Z~4 .
and the kinetic energy represented thereby may be used, for example, for the feed pressure. The lower molecular weight assay may exit with some portion of the rotational velocity due to frictional drag, or simply may exit with some velocity v~, vr, or v~ (where vz represents axial velocity, Vr repre-sents radial velocity, and v~ represents axial rotational velocity) by the particular design of the deflector, and this kinetic energy may also be utili~ed, for example, as feed pressure. Generally, the high rotational velocity of the - 10 deflector is usea to laterally accelerate the gas for a high lateral velocity, and a major portion of the energy of this lateral velocity may be recovered by channeling the gas to , ; accelerate ~he deflector in the direction of rota~ion. There may be a plurality, such as from about 3 to about 9 or more disc-chambers in the processing unit 500 with conventional cascaded matched flow interconnection.
The processing flow of a particular separation disc-chamber in the design of the illustrated embodiment is proportional to the width of the input opening of the individual deflector blades, which are illustrated in detail in FIGURES 6 and 7. FIGURE 6 is a side illustration of a deflector blade unit 602, which i9 bounded by an inner cylindrical shroud ring and seal unlt 604 and an outer . cylindrical shroud ring and seal unit 606. Identical i5 deflector blade units inclùding adjacent units 601, 603 are also regularly mounted between the shrouds 604, 606 to form the rotor unit. In the embodiment of FIGVRE 6, the deflector :, .
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blade unit 602 is adapted to be rotated in a counterclockwise d~rection as shown by the directional arrow so that it (and the other blade units) will intercept gas admitted into its path through holes in the gas distribution ring. Gas inter-cepted by the deflector unit 602 is forced into the curvedopening 608 of the deflectox unit by the rotational motion.
The moving rotor divides the gas at a knife-edged central flow separator 610 positioned generally centrally within the .throat of the passageway 612. The gas is forced to travel through either laterally curved flow channel 614 or oppositely -curved flow channel 616, which are generally bilaterally symmetrical in respect of a cylindrical surface of rotation positioned centrally between the shroud rings 604, 606.
--Gas which is forced into the outer flow channel 614 . is abruptly laterally accelerated outwardly against curved -surface 618 by motion of the rotor element and curved surface blade unit 602. A higher molecular weight portion of this ; . outwardly accelerated flow is diverted by a knife-edge deflector or skimmer means 620 and conducted to a channel 622 which curves downwardly with respect to the plane of the illu~tration as shown by dashed line in FIGURE 7. Gas which is not diverted to channei 622 is forced by the rotational motion of the unit 602 to proceed along channel 624, where it i8 laterally accelerated inwardly by wall 626 having a I 25 curvature opposite of that of 618. A higher molecular weight ¦ portion of the laterally accelerated stream may be similarly ¦ - diverted to channel 628 which, like channel 626, bends ' ~ ' :' , ' . . , ' ' ..' ' , ~ 33_ .
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gradually into the plane of the drawing. The motion of the - deflector blade causes gas which is not deflected to channels 626 or 628 to be displaced relatively along channel 630 which is curved upwardly in the plane of the illustration. The central rear portion of the unit 602 is provided with an opening 632 which permits gas to be ; introduced into the zone sufficiently in advance of the next succeeding de~lector blade unit 603 to pro~ide for desired ~ distribution and amount of feed gas under operational 10 conditions of input gas, flow speed, deflector blade rotational speed, and deflector blade dimensions~ The lower siae of the deflector blade 602 is generally symmetrical with the previously described upper portion as shown in the drawings.
The construction of the deflector unit 602, portions of the adjacent side stationary disc elements 706, 710, and gas service means are shown in FIGURE 7, which is a partial ~ide cross.sectional view from the front of blade unit 602 as taken thxough line 6-6. Gas to be supplied to the deflector blade 602 is conducted from manifold 703 of manifold means 501 - and manifold 705 of manifold means 503 to input conduit 701 .
and conduit 707 to a ring shaped recess 704 in stationary disc element 706 and to a similar ring-shaped recess 708 in the other disc element 710. The recesses 704, 708 are provided i 25 with a gas permeable wall, which in the illustrated embodiment i8 ~ ring-shaped perforated sheet 607 in.a plane immediately ad~acent the side walls 714, 716 of the deflector blade unit ; . . ' ' '' ;,;' , ' . -34-., .
~' '` ' '~ , '' ' ' , ll~;)~ZO~
602. Deflector element channels 622 and 628, which are channels for a heavier molecular weight fraction, are ~axially) bent to dischar~e into recess 718 in order to divert and segregate this fraction upon motion of the deflector blade unit into the recess 718 and from there via conduit means 721 - ~ to manifold element 723. Similarly, the lighter fraction,-which is channeled in flow channel 630, is forced by motion of the deflector blade unit and the (axial) curvature of the channel 630 into recess 720 and from there via conduit means 725 to manifold element 727. The gas directed to recesses 718 and 720 has an axial and radial velocity component which may be converted to pressurq, and the pressurized gas may be conducted thereafter to become the respective input streams of subsequent cascaded processing disc-chambers, which may be located axially adjacent the illustrated disc-chamber. The inner channels of blade 602 are similarly diver~ed to recesses 729, 731. The multiple separation unit of apparatus 500 may be connected in suitable cascade manner by means of appropriate connection of the manifold means (such as means 501, 503, 505) of the respective separative units.
~ Illustrated in FIG~RE 8 is a partial side view of another embodiment 800 of a turboseparative apparatus deflector blade unit and the surrounding stationary sur~aces. The embodiment illustrated in FIGUR~ 8, has a deflector blade similar to that illustrated in FIGUgES 6 and 7, with the principal exception that the blade unit orientation has been rotated 90 so that the lateral displacement of the feed gas . ' . , .__"., ' " ' ' ' ' ! .
72~ .
is in an axial, rather than a radial, direction. In other variations, an intermediate blade orientation may be used having radial and axial components of displacement. In the embodiment of FIGURE 8, the outermost displaced higher S molecular weight stream lanalogous to the gas channeled in channel 628 of the embodiment of FIG~RE 6) is diverted axially to recesses 802, 804. The lighter molecular weight fraction of each side of the bilaterally symmetrical flow channels is diverted into recesses 806, 808, and the innermost higher molecular weight fraction (analogous to that of channel 622 of FIGURE 6), is similarly conducted to recess 814, 816.
The input gas to the separation zone to be inter-cepted by the deflector blade is introduced to recess 810 which is provided with a gas permeable wall such as a perforated cylindrical sheet 812 by means of supply conduit 820. The discharge flows to recesses 806, 808, 814, 816 are centrifugally pumped to those recesses, and a design element of centrifugal pumping from the rotational motion imparted to the processed gas channeled to recesses 802, 804 may be -- provided. The respective discharge flows may be conducted through the casing 822 of the stator element ~or appropriate subsequent treatment such as cooling, pressure energy utilization, etc~, and cascade interconnection. It is noted that the dif~erent high molecular weight cuts may be kept separate in this embodiment to enhance cascade effects.
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The embodiment in FIGURE 8 is further illustrated in the cross-sectional side view of EIGURE 9, where it may be seen that the flow channels such as flow channel 302 of the deflector blade may be radially outwardly divergent in consideration of centrifugal gas motion.
- While various deflector blade units which produce lateral displacament of the feed gas in a radial direction and in an axial direction have been described, it will be app~eciated that deflector blade orientation.at intermediate positions may also be provided which produceS a combination of axial and radial accelexation. Furthermore, while specific ~eed gas supply and discharge gas configurations have been described, it will be appreciated that various other types of gas service designs may be utilized.
Illustrated in FIGURES 10 and 11 is another embodiment of separative apparatus 1000. A confined gas cloud introduced .~ into channel 1004 of rotary disc element 1006 will with an outwardly radial velocity component travelling radially on the . plane of a rotating disc 1002 tend to describe an Archimedean 1 20 spixal as a trajectory on the disc. Relative to the rest frame, - the gas does not have a velocity component in the vz and v~
directions. In the illustrated embodiment, a tube 1004 confining the gas is provided in the form of the "A spiral", so that gas introduced at the axis of the rotating disc slips by inside the tube with a high velocity v~ relative to the tube ¦ wall. A sudden displacement of the tube in a radial or axial ¦ direction at point 1006 bends the gas with supersonic velocity¦ . V~ 3 nr~ A portion of the hLgher molecular weight assay is . ! .
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i~ substracted right after the bending, and there can be several bendings in the axial z direction for substractions as shown in FIGURE ll. The friction with the tube wall accelerates the gas in the v~ component which can be trans- -lated to a pressure energy for feed pressure and which may be recovered through use in accelerating the rotation of ~he disc as described previously. There can be many tubes mounted on a disc, and many discs Porm a processing unit.
- Control of degrading turbulence is relatively simple in this design as a bending t~be running into gas is used although there may be difficulties in maintaining a flow at high Mach number in this geometry.
While the present invention has been particularly described with respect to certain specific embodiments, it lS :will be appreciated that various modifications and adaptations may be made without departing from the spirit and scope of the present disclosure. For example, different variations of specific elements described in connection with one type of turboseparative apparatus may be adapted for use in connection with another type of turboseparative apparatus embodiment.
Thus, it will be appreciated that compound blade elements such as shown in connection with supersonic turboseparative apparatus and in which successive cuts of high and/or low molecular weight fractions may be made in cascade fashion within a rotor or stator unit for apparatus such as illustrated in FIGURES 1-4.
~ Furthermore, while in the illustrated embodiments, separation j is made ln respect of a density gradient having increasing ~''. . ' , "
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density in the direction of the applied centripetal field, another advantage may also be taXen of the lateral accelera-tion produced by the moving surface. In this connection, means, such as a suction slot or permeable diffusion surface (e.g., which might be located at numeral 51 of blade 30 in FIGURE 3 and connected via a longitudinal channel in the blade to a relative vacuum source acting at the radially interior end of the blade element) for taking in a portion of gas in the .wake of a moving surface or blade element, might be used to separate a lower molecular weight fraction which would preferably diffuse into the blade wake region under operating conditions. In another variation, the centrifugal pumping energy of gas in a separation zone not scooped into the : interior of a blade may be recycled to the system, as well as that scooped into the blades. Such modifications and adapta-tions are intended to be included within the scope of the invention as defined in the following claims.
,Various of the features of the invention are set foxth in the following claims.
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curved~jet separation treatment in a counterflow cascade system to cumulate the incremental separative effect of each curved-jet passage of the gas.
In such curved-jet systems, pressure energy of the gas is converted into curved flow energy with a curved convergent-divergent nozzle, and a carrier fluid with a very low molecular weight is employed to give the high molecular weight gas a high flow velocity. Since the throughput L of equation (4), supra, is also proportional to the flow velocity, vf, and the square ~f the effective separative factor ~ is proportional to Vf4 , the useful separative work ~U becomes proportional to v~5 .
~0 Furthermore, the difference of molecular weight of an isotope -- mixture also gives rise to a difference of sedimentation time in a low molecular weight carrier fluid. Therefore, in a high centrifugal field, this difference of sedimentation time may be used to obtain a i~lightly higher separative factor ~ than I 25 that of the corresponding equilibrium value of a centrifuge.
I The diffusion time of curved-jet systems may be optimally selected by pro~iding the curved wall with a prede-¦ termined relatively small length in a direction along the gas , ~ . . . ' :~
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` ~1072~4 , . . . : , tra~ectory, while providing for system throughput'by making . ' the no~zle and wall relatively long in a direction orthogonal ' to the gas trajectory. -However, a major portion of the pumping energy in curved-jet uranium isotope separation is S wasted in processing the low molecular weight carrier fluid, - and the pumping energy and displaced momentum are generally ' not recoverable. The separation of the carrier fluid also requires some work. These considerations push the overall energy needs to a high level of about 4000 kilowatt hours per separative work unit, making 'the c~rved-jet method un-attractive without an order of magnitude reduction of its energy consumption. In order to partially alleviate this problem, it is possible to combine and carry out th'e pumping and carrier fluid separation in one rotating chamber to~save ; 15 a fraction of the energy requirement, thereby reducing the energy requirement to a reported value of about 3500 kilowatt Xours per separative work unit. ~owever, this level of energy oonsumption per SWU is sti}l undesirably high.
'' ' ' ~t w~ll be appreciated that basic principles of mechanical systems of separation, such as gaseous diffusion, centrifugation and curved-jet separation are in genër'al' terms conceptually relatively simple, and the estimation of the ' efficiency of such systems i9 relatively straight forward ' (although the achievement of such efficiency in actual practice 2'5 may involve substantial technology). However, given the design of such a system, it i8 difficult to provide drastic'improve-I ment in performance within the constraint of the particuiar ¦ '' '' design . . . ,., - , .
' . , , __ ' , .
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~ ccoraingly, it is an object of the present inven-tion to provide new methods and apparatus for the molecular weight separation of gases. It is a further object to provide such methods and apparatus having improved efficiency and/or throughput characteristics. These and other objects of the invention will ~ecome apparent in view of the following de-tailed description and the accompanying drawings, of which FIGURE 1 is a perspective view, partially broken away, of an embodiment of turboseparative appratus particu-larly adapted for operation at subsonic speeds;
FIGURE 2 is a schematic side view of the embodi-ment of FIGURE 1 taken through line 2-2;
FIGURE 3 is a schematic top view taken through line 3-3, illustrating blade and gas supply features of the embodiment of FIGURE l;
FIGURE 4 is a schematic illustration of another embodiment of blade and gas supply design suitable for use in apparatus like that of FIGURE l;
FIGURE 5 is a perspective view, partially broken away, of apparatus adapted for gas separation at supersonic speeds;
FIGUXE 6 is a partial axial side view of the apparatus of FIGURE 5 taken through line 6-6;
FIGURE 7 is a partial cross-sectional front view of the rotor and stator assembly of FIGURE 6 taken through line 7-7;
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.
FIGURE 8 iq an illustration of another embodiment - of ~tator and rotor configuration suitable for use in connec-tion with apparatus like that of FIGURE 5: - -FIGURE 9 is a partial side view of the apparatus S of FIGURE 8 taken through line 9-9;
FIGURE 10 is a partial schematic side view of ~nother embodiment of separative apparatus, and FI~URE 11 is a side view of the apparatus of FIGURE
- lb taken through line 11-11.
. . . .
Generally in accordance with *he method of the present invention, a gas mixture to be separated in respect of its diferent molecular weight components is provided in A sepa~ation zone, and a moving surface is forced through - the gas in the separation zone to impart an impulsive type of centrifugal bending", or acceleration of the gas lateraliy o~ the direction o movement of the moving surface.
Th~ lateral àcceleration may pro_uce a molecular weight density gradient in the gas accelerated by the moving _ surace, with maximum density at the moving surface and with ; io decrea ing density as a function of lateral distance from the surface. A higher molecular weight portion of the gaa Imme-d$ately adjac~nt^the surface may then be separated from lower molecular weight gas. The gas portions of differing molecular ; - weight obtained in this manner may be each subsequently sub-~ 25 jected to separation treatment to produce a high degree of I separation o the components of the gas.
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The method is pa~ticularly adapted for use in the enrichment of uranium compounds in the u235 isotope, and in ' this connection, the gaseous uranium hexafluoride compound is conventionally used for enrichment purposes. However, methods S and apparatus in accordance with the invention may also be ~ used in the separation of other isotope mistures ~e.g., radio-,isotope separation or enrichment) and in the direct separation of gaseous mixtures of different elements or compounds (e.g., , separation of the component gases of air).
! lo The solid surface forced into the gas mixture is desirably a curved surface having a surface curvature such that a relatively uniform centrifugal field may be provided along at least a portion of the curved surface as the surface is forced ~ into the gas mixture. : -- 15 ' ~hrough the step of forcing a curvea surface through ' a zone containing the gas mixture, a high relative velocity may '~ ' , be maintained between the gas and the moving surface, and this may be accomplished without the use of a carrier fluid when the gas components to be separated have high molecular weight.
Furthermore, the motion of the curved surface is desirably rota-, , .
- , tional motion, which may produce centrifugal or axial pumping , energy in the separation process which may be recycled or otherwise utilized without substantially disturbing the effect-.
, .iveness of separation. Moreover, the laterally accelerated gas may be subsequently deaccelerated, in a direction opposite that of its original acceleration, by mea~s of a suitably positioned ' surface in order to recover a portion of the energy expended ' in the original acceleration of the gas.
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Apparatus in accordance with the present invéntion generally comprises means for confining a gas mixture in a .
separation zone, a plurality of blade means each defining at least one curved surface for laterally accelerating gas L 5 upon motion therethrough, ~eans for moving the blade means in the separation zone to produce a density gradient in the gas adjacent the curved surface of the blade means. The apparatus generally further comprises means for separating the gas with respect to the density gradient produced by blade motion.
Desirably, the blade means will be rotatably mounted so that the curved blade eiements may be rotatably forced to intercept the gas mixture, and the apparatus may further in-clude means for recovering the kinetic energy of the gas laterally accelerated and/or centrifugally pumped by the ~oving blade elements. Furthermore, a plurality of such turbo-ceparative elements may be appropriately connected in a cascade manner ~o provide for cumulation of separation.
Turning now to the drawings, the present invention will now be more particularly described with respect to the embodiments of apparatus shown in FIGURES l-~.
Illustrated in FIGURE 1 is turboseparative apparatus ; , lO which is particularly adapted for subsonic operation. The illustration of the apparatus 10 is broken away to display ,a separation zone 12 defined by the end bulkhead 14, casing elements 16 and 18, and gas supply disk 20. The separation ~one is hermetically sealed with the exception of gas entrance . 'I .
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and exit supply means, which wi11 be discussed in more detail hereinafter. The apparatus further includes a rotor element 22 which is rotatably mounted on driveshaft 24.
~he rotor element 22 comprises a portion of a conical inner drum 26, a cylindrical outer shroud ring 28, and a plurality of hollo~ blades 30 which are regularly spaced about the rotor element 22. The entire rotor assembly is radially symmetrical with respect to the axis of the driveshaft 24, and is adapted to be rotated in a clockwise direction in respect of the view of the drawing as i~dicated by the arrow at the driveshaft-bulkhead bearing 24. The blades 30 of the rotor element are generally of airfoil shape de-signed to minimize turbulence, and in the illustrated embodi-ment.are oriented so that a "sharp" edge of the airfoil is ; 15 the leading edge in the direction of blade motion throughthe separation zone 12. Each of the blades 30 has a curved ~urface 32 for laterally accelerating the gas upon rotation of the rotor element.
Also contained within the separation zone 12 and adjacent the first rotor element 22 is a second rotor element 34 comprising a second set o~ blades 36 which are similarly mounted on the conical drum 26 and surrounded by a cylindrical shroud ring 38. The blades 36 of the second . rotor element 34 are also of a hollow airfoil design to : 25 minimize turbulence, and are mounted at their root ends in regular array on drum 26 adjacent blades 10, but in the illustrated embodiment have an orientation opposite that of ~ 12-.
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.
the blades 30 of the rotor element 22 so that the "blunt"
edges of the blades 36 are the leading surfaces in the di-rection of blade motion. Like rotor element 22, rotor element 34 is radially symmetrical about the axis of the drum 26 and driveshaft 24, and its blades 36 terminate at their peripheral tip end in attachment with a cylindrical ring shroud 42.
The ring shrouds 28, 42 define the outer bound--~ ary of their respective rotor elements 22, 34, and in turn define the inner boundary of centrifugal pump diffuser and collector zones 44, 46 surrounding the respective rotor elements. In this connection, the shroud rings form a ro-tating seal with seal element 46 of their respective casings 16, 18 to prevent passage of gas from the separation zone 12 ' into the diffuser and collector zones 44, 46, with the excep-; 15 tion of gas from the interior of the blades 30, 36. The second set of blades 36 is positioned to intercept and re-cover momentum from gas deflected by the first set of blades and both sets of blades are provided with means for admittlng gas to the blade interior, as will be discussed in more detail hereinafter in connection with FIGURE 2.
As indicated, each'of the blades,30 and 36 is , . hollow, being provided with radial passageways 38, 40 ,, longltudinally of the airfoil cross-section. While the blades ~0, 36 are substantially closed adjacent the drum 26, the , 25 passageways 38, 40 of blades 30j 36 each communicate respect-;, ively ~ith diffusion and collection zones 44, 46 by means of , paEsageways 48, 50 provided through shroud'rings 28, 36 for - ,' th~s purpose.
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~O~ )4 Gas may be conducted from each diffuser and - collector zone by means of a suitable conduit, as a product discharge, or ~or appropriate reintroduction in a cascade manner into another separation zone. In the illustrated S embodiment, a conduit 52 is employed to conduct gas from the diffusion and collection zone 46 to the manifold 54 of the input disk 20 which serves an adjacent separation zone.
While direct conduction of gas from zone 46 to manifold 54 is shown for convenience, the gas may advantageously undergo intermediate processing steps such as cooling and enersy recovery steps, a.s will be discussed in connection with FIGURE 2.
The manifold 54 of the supply disk 20 surrounds a plurality of radial feed tubes 56 which are regularly spaced about the axis of the drum 26 and through which input gas is supplied to a separation zone adjacent zone 12.
Separation zone 12 itself is supplied with input . gas by means of a manifold 62 which in turn supplies a plural- ~ :
ity of radially symmetrical and radially projecting feed tubes 2Q. 56. An adjacent zone is supplied by manifold 54. The manifolds 62 and 54 may be supplied by suitable supply conduits ~not shown in FIGURE 1) from the desired gas source of appropriate cascadc staging. It is noted t.hat the disk element 20 i5 . po~itloned between two adjacent separation.zones and serves ' ' , ... . . .
' ' ' . ' . .
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each zone through independent manifolds 54, 62 and their respective supply tubes, while the bulkhead disk 14 is at the end o~ apparatus 10 and need only serve separation zone 12.
Turning now to'FIGURE 3, the operation of the S' separation zones of the apparatus 12 will now be described with reference to the simplified schematic representation of a separation zone 100 there shown in schematic top view bounded by two.stationary supply disks 102, 104 and radially tow~rd the axis at one pair of deflection blades 30', 36'.
The direction of rotation of the blades is toward the right as-shown by arrow, and gas to be subjected to treatment in the-separation zone 100 is introduced int.o the zone by means of feed tubes 106, 108 supplied by their respective manifolds . . . ..
,(not shown). The feed tubes are longitudinally hollow and 15'' have a longitudinal convergent-divergent slot nozzle 110, 112 adapted to provide efficient discharye in a direction opposite .~ .
' the direction of motion of the blades 30', 36' and minimization , of discharge turbulence. The blades themselves are hollow, and are each respectively provided with a longitudinal opening 108, 110 extending substantially the radial length of the blade ' ~or accepting gas from the zone 100 into the hollow interior o,f the,blade. The 4irst blade 30' has a sharp edge 112 of its a~rfoil configuration oriented as the leading edge with an , angle of attack approximately equal to the flow streamline of , 25 the gas, which in the illustrated embodiment results in an attack vector approximately parallel to that of the direction , of motion of the blade 30'. The blade 30 has a surface 118 ," ,, '.' ' . . ' " ' ' ~
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tra~ling the leading edge 112 which has a positivé curvature in the direction of the top of the drawing. The curvature of the surface 118 provides for lateral displacement of the gas in the direction of curvature upon rotational motion of the bladè, and in this connection is designed in accordance - - with aerodynamic principles to subject gas forced over the surface 118 by motion of the bladç to an impulse accelerative field under streamline (non-turbulent) flow conditions. Under these conditions, higher molecular weight components of the gas tend to preferentially move toward the curved surface 118 and lighter components tend to preferentially move away from the surface, producing a density gradient in the direction of ...... ... . .
;-~ the applied impulse field upon passage along the curved surface 118. Subsequently, at blade slot 114, a denser ~raction adjacent the curved surface may be diverted to the interior of the blade 30 by a slot knife edge, or ski~mer means 120 projecting in a predetermined manner into the streamline flow from the surface 118. The fraction of the flow diverted to the interior of the blade will depend on a number of factors such as the blade speed, blade~dimensions, blade curvature, ~ skimmer position and opening width, surface smoothness, and ga~ mixture density.
As indicated, lighter components of the gas tend to be relatively displaced away from the curved surface 118 upon passage thereover, and a portion of this lighter fraction may be diverted into the interior of the sscond blade 36' through blade intake slot 116 which is appropriately positionFd to ' ~ ' ' .1 , . . . .
, ' ~ . ' ' . ~
I :16-~, ~l~qZ04 lntercept a portion of the lighter density flow stream under operating conditions. The remainder of the gas, which has been given a velocity component orthogonal to the direction of blade motion primarily through application of impulse forces ~as well as a velocity component in the direction of - ~lade motion through drag and impulse forces) is directed to intercept surface 122 of blade 36' which has a countercurvature to recover as a rotational force the lateral gas momentum imparted by the curved surface 11~.
The heavier gas portion diverted to the interior of the blade 30' will be expelled from the blade through its shroud passageway into the respective diffuser and collector .--zone in the manner of a centrifugal pump, and may be conducted . . therefrom as a product stream or for reintroduction to another . 15 separation zone operating on higher density fraction gas.
Similarly, the lighter gas fraction diverted to the interior . of the blade 36' will be centrifugally pumped from the zone and may form a product stream or a source stream for another -~ separation zone adapted to process a lighter gas fraction. ...... ,...... . :
As indicated, processing may be cascaded by means ~~ of a plurality of separation zone units a~d such cascading is generally conventional in the separation of mixtures of high ~olecular weight materials with a small molecular weight difference such as ~F6 isotope mixtures. In this connection, the turboseparative apparatus 10 of FIGURE 1 comprises a plurality of axially stacked separative units 201, 203, 205, 207, 209 which are schematically illustrated in side view by ~; ' ' ' I ' . .. .' : . !
1. .
. -17-.. - . , :
- FIGURE 2. In FIGURE 2, the apparatus 10 is shown as comprising .
a plurality o aiternatingly adjacent rotor element pairs 204, ~06~ 208, 210, 212 and stationary feed disk elements 214, 216, 218, 220 each having appropriate manifolding and feed tubes for S separately feeding each side of each disk. The separation units 201-209 are respectively made up of one rotor element pair and the adjacent feed side of each adjacent feed disk.
~he rotor pairs may be mounted on a common drum 26', and each stationary disk element forms an effective rotating seal with the drum 26' to prevent unintended flow ~etween separation unit sections.
In operation, an input feed mixture 240 to be subjected to separation treatment may be conducted by conduit means 242, 244 to the respective feed tubes 246, 248 for the separation zone oontaining the central rotator blade pair 250.
The heavier gas component stream 254 diverted and pumped by . the first blade set 252 of the rotor 250 is supplied as the input stream for feed tubes 256 of disk 218 of another ~adjacent) separative unit, while the lighter gas component forced into and pumped by the countercurved blade se~ 258 is supplied as an input stream to the feed tube 260 of another separative unit. The lighter and heavier components of each separative unit are similarly fed respectively, in cascade manner, to lighter and heavier separative unit processing stages ~in terms of component gas mixture being processed) a~ shown in FIGURE 2, with the heaviest gas product stream being withdrawn from the blade set of the l~st "heavy gas"
stage, and the lig~test gas product strea~ being withdrawn from the light fraction blade set of the last ~light gas~ -~ 30 stage of the cascaded system. In the schematic illustration : . .
.
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.
of ~IGURE 3, with the indicated blade orientation, gas feed configuration and rotational direction, the light fraction head output stream 280 o~ blade set 204 represents the lowest ~olecular weight output stream illustrated, and the density S of gas processed by each separative unit increases with increasing reference numeral from separation zone 201 to zone 209, where the high molecular weight tail stream from , blade set 214 represents the lowest molecular weight output -stream illustrated. Of course, additional separative units might be provided in cascade manner axially of those illustrated.
The gas centrifugally pumped by the respective blade sets may be subjected to various processing steps before reintroduction into the system, and such processing is indicated schematically in FIGUR~ 2 by processing blocks 270.
In particular, it may be desirable to cool the gas to a pre-determin~ed temperature before recycle into the system, and such cooling may be accomplished by conventional heat exchange apparatus and techniques. It may also be desirable to recover energy from the centrifugally pumped stxeam and for this purpose a suitable turbine, preferably connected directly to ,;,"..
the drives}taft or drum of apparatus 10, may be employed. It is noted that cooling, if any, will desirably follow any energy recovery step, and that integrity of the respective streams should be maintained without mixing with other streams oE different molecular weigbt distribution in respect of the components to be separated.
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In connection with the general operational per~
formance parameters of apparatus such as illustrated in FIGURES 1-3, it may be considered from Equations 1-3 that the separative constant generally depends upon an altered velocity of the gas while the gas i5 laterally displaced, or "bent". The altered velocity of the illustrated apparatus 10 is approximately the cutting speed of the blades through the gas in a separation zone where the gas is kept relatively stationary while being accelerated laterally by means of cur~ed surfaces forced through the gas at high speed. The first set of curved surfaces, or blades, have openings at their trailing edges to scoop away a portion of the higher molecular weight tail stream ("depleted" stream in uranium isotope separation). A second set of curved surfaces co-moving with the first, and having a countercurvature to recover some of the laterally altered momentum is also provided with i openings at the leading edges to take in a portion of the lighter molecular weight stream ("enriched" stream in uranium isotope separation). There are many pairs of appropriately positioned hollowed blades arranged in the form of a rotor element similar in some respects to those of a turbine. Gas, once scooped into a hollowed blade, or the intake tube, will be swung to the blade tip, and exits from the rotating disc, converting kinetic energy into pressure. There are also -~5 stationary walls in the form of discs intervening between the rotor discs, and feed gas swung and pressured from the rotation of the preceding disc enters a separative disc-chamber through 7Z~ -feed tubes in the stationary disk wall. The feed tubes and wall structure separating th~ blade ch2mbers may also serve to retard the co-rotational tendency of the gas. In this connection, the retarding effect of the wall structure may be enhanced, such as by providing projections lS0 and by ~ ~ directing feed gas axially into the blade chamber rather than ; in the direction of blade rotation as shown by feed tube embodiment 152 of FIGURE 3. Moreover, the co-rotational tendency may also be counteracted by having the gas discharge 10 from the feed tubes in a direction opposite the direction of blade rotation as shown in FIGURE 3 by feed tube elements 154, 156, although it will be appreciated that the input pressure should exceed the static pressure head from any rotational velocity of the gas at the points of introduction. The 15 mihimum input pressure may be reduced by partially shielding the input noz~le, by limiting the points of input to inner radial positions where any co-rotational velocity would be lower, etc. A co-rotating drum forms the base for the inner rotational structure or central portion of the turboseparative 20 apparatus where the speed is low, and, as indicated, excess centrifugal feeding pressure may be used to accelerate the ~ .
drum The radial dimensions of the drum may be adjusted to - match the input-output specifications of the various flows in - ~ respect of different units of the cascade system. The gas 25 mixture to be processed may be main~ained at a temperature su~table to provide an appropriate vapor pressure, which may be in the case of UF6, for example, about two Atmospheres.
, The frictional energy dissipated in each disc-chamber will generally be sufficient to keep a higher molecular weight ¦ 30 gas such as UF6 at a desired elevated temperature, and excess . ~
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1~7;~0 ., . ' heat may be removed ~hrough the co-rstating drum, the casing, and/or from the process gas streams as indicated previously.
In estimating and discussin~ the processing capacity and unit energy requirement for apparatus of the type illus-S trated in FIGURES 1-3, an exa~.ple of moderate design values may be considered. In the case of turboseparative apparatus ~bout one meter in diameter moving at a peripheral speed of about 500 meteis per second, the cutting speed of the blades may range from about 500 to about 300 m~s, with an average spesd of about 400 meters per second. In such an apparatus having nine cascaded separation chambers and operated with UF6 at a pressure of two Atmospheres there are about 0.01 grams of U238 per cc. If the input velocity of the feed st~eam through the tubes having a cross-sectional area of abollt 20 square centimeters is about 200 meters per second, a throughput of about 4 kilograms per second may be provided.
An effective separative factor for each separation unit or chamber may be, using the equilibrium centrifugal value:
~i = Am v / 2 R T = 0.046 ~5) ~ The capacity per separative unit stage may be:
~Ui = ~ ~i / 4 - 2.12 gts - 6.65 x 10 kg SWU/a (6) . For the nine-stage turboseparative processing unit , 2 under consideration, the useful work may be:
0.60 ~illion SWU~a . ~7) , : ..
j The energy re~uirement may be considered as:-. ~ 2 E c L x ~v ~2) x fl x f2 x number of separative units ~ - t8) i ~ . ..
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.
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~1~7Z04 where fl is the frictional drag of the blade ~a function of the bending angle and its surface smoothness) and f2 is the feedback factor where the pressured gas provided by rotational motion of the blades is reused to accelerate the drum. Flux (gas portion) scooped away is considered as part - of the drag. The factor fl x f2 may, for example, approximate 1/5, and for a separative unit system, E may be estimated at about 580 kilowatts. Since the unit energy requirement is representable by the factor E/~U, the unit energy requirement lC may be estimated as follows:
unit energy requirement = E/~U = 8.4 kwh/SWU ~9) The indicated flux through the tubes may be higher, the factors fl and f2 being dependent upon design factors.
Moreover, it is noted that such a relatively small turbo-separative processing unit may be capa ~e of processing on the order of about one million S~ annually, with a unit energy requirement which may be less than 1% of the current value by diffusion of 2500 kwh/SWU.
The unit energy requirement may also be considered - by comparison with the requirements of conventional processing techniques. In the curved-jet method, conventionally only one part in ten of the pumping energy directly pumps on the seed gas, and by processing without the use of a carrier fluid, the energy requirement may be reduced by an order of magnîtude.
I ~ *~dditional energy saving also results from not having to ! separate the seed gas from the carrier gas. The rotary blade . . -- - : .
~'~ . ' .' ' ' - ' ,. . '' . ,__ . ...
. ~ ' elements form part of a centrifugal pump, and part of the ~inetic energy gained is recoverable as pressure energy of the feed gas by directing it to accelerate the rotating drum.
lf all these considerations combine to a factor of five, the '5 conventional curved-jet energy requirement of, say, - 4000 kwh/S~ may be reduced by a factor of a~out fifty.
Moreover, while the internal fric~ional heat generation of the nine unit turboseparative apparatus case previously considered may be conservatively estimated at about 100 kilo-watts per unit, this value is probably excessive and could be substantially reduced by appropriate design considerations intended to reduce turbulenf~e and other frictional losses.
Accordingly, a reduction of energy requirement by a'factor of, say, one hundred, both in capital cost and in energy consumption, would appear to be appropriate to the turbo-separative apparatus.
: - Contxol of degrading turbulence in the separation chamber is very important in order to produce a predicted and - desired value of separative factor ~. In this connection, the axial dimension of the chamber may be made large to permit - turbulence to decay. The dimension of the hollowed ~Iades may be made small so that the fluid dynamics operations performed by the blades are at a scale smaller than the scale of the ' turbulence of the gas in the blade chamber. In this'latter connection, it is noted that the blades and curved surface dimensions may be substantially smaller'than indïcated in the drawings for purposes of illustration, and for uranium isotope 11 ' ' ' ' "
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separation the blades and curved surfaces may be quite small and the skimmer cut thickness may be on the order of magnitude of the shock wave thickness. In addition, the bladie pairs may be brokan up, with one turbine blaae set processing the S head stream, and the other oountercurved turbine blade set processing the tail stream, with the two turbine sets feeding each other to form a processing unit, although this variation has the disadvantage of not providing for opposite curvature blade momentum recovery.
Since the higher molecular weight tail assay may be scooped away at the trailing edge of a blade, this function i8 less susceptible to the degrading effect of turbulence, and the two sets of blades, one curved and the other counter-curved, may both be of the type which divert the high molecular weight fraction. The low molecular weight fraction may be permitted to travel or ~leak through" in a suitably controlled manner along the axial direction by providing an appropriate stationary disc element. Further in this connection, the axial velocity of the gas imparted by appropxiate rotor elements may be converted to pressure énergy and utilized in the system.
Another variation providing for higher throughput comprises two sets of blade pairs in one separation chamber which are adapted to rotate in opposite directions, thereby countering the co-rotational motion tenden~y of the gas while utilizing the rotationally induced velocity components to separative function advantage. The oppositely rotating rotor . i ...................... .
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blades may ~oth be of the type having means for generating a centripetal field and means for separating a heavier fraction, such as the s~immer means whic~ scoop away the higher molecular weight tail assay and feed it back to a S preceding higher molecular weight separation unit chamber, while the lighter head assay is permitted to travel along the axis to succeeding lower molecular weight separation unit chambers, in a processing direction opposite to that of the tail assay stream. Appropriate mechanisms to turn the blade sets in opposite directions may be housed along the axis within segmented drum sections.
Other variations of blade configurations particularly adapted for subsonic turboseparative methods and apparatus are illustrated schematically in FIGURE 4 of the drawings, which - 15 is a partial schematic side view of two rotor elements 302, 304 and two stator elements 306, 308 stacked along an axis 310 of radial symmetry. Rotor elements 306 are adapted to turn about axi8 310 in the direction of the indicated arrows, and it is to be understood that there may be additional rotor and stator , elements stacked along the axis 310 "above" and "below" those illustrated. The rotor elements 302, 304 have a plurality of s regularly spaced blades 318 for laterally accelerating gas, and the stator elements 306, 308 have a plurality of regularly spaced redirectional blades 314, 324 for redirecting gas impelled by the rotor blades 318 with a force vector in a direction opposite the rotational direction of the blades 318.
A gas mixture to be subjected to separative treatment may be '.' ..'' ,,. .
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11'~7Z~)4 introduced into the system by means of longitudinally placed nozzle elements 312 of the impulse-curved redirectional blades 314 by means of suitable manifolding and supply means such as that illustrated in FIGURES 1 and 3. The gas discharged by the nozzle elements 312, which may be of isentropic expansion - type to provide minimization of discharge turbulence and maximum efficiency in conversion of feed pressure to gas velocity,is directed at an angle with respect to the axis 310 ~hich provides a discharge velocity component opposite the directional rotation vector of the rotor elements and which may qenerally coincide with the impulse-redirected discharge angle provided by the curvature of the blades 314 in respect of gas originating from the next lower rotor element (not shown). This gas discharge direction and redirected gas direction from the stator blades 314 also may correspond .. . .
generally to the operational angle of attack of the blades 318 of rotor element 302, which are of the hollow "scoop" higher molecular weight separative type and which have curved surfaces 320 for laterally accelerating the gas and longitu-dinal openings 319 bounded by knife edges 321 which divert ~ internally of the blades a portion of the gas representing a higher molecular fraction. The diverted gas is centrifugally pumped by the blades to a diffuser-collector zone such as shown in FIGURE 1 to a preceding higher molecular weight stage ~i.e., a lower stage in tbe illustration), and may be previously cooled or extracted of its pressure energy. The gas vhich is not so diverted has been provided with a velocity ;. j ' , " ' . I ' . `
-27;
:
1~7Z04 component in the direction of the axis of the turboseparative apparatus, and a velocity component in the direction of blade rotation. This gas is directed to stator element 306 which has curved blades 314 with an inlet angle generally co~responding to the velocity vector of this remaining lighter gas fraction which has pass~d through rotor element 302. The impulse redirectional blades 324, like ~lades 314 of the preceding stator element, redirect the flow of lighter fraction gas from the preceding rotor element and provide for reintroduction of a heavier fraction from a succeeding rotor element ~not shown) in a direction appropriate for intercep-tion by succeeding rotor element 304. It will be appreciated that a plurality of alternating rotor and stator elements may ~e provided and connected in a cascade manner, and that the - 15 input feed gas to the resulting cascade system may be fed to an axially centrally located stator element. Upon introduction ; ~f-a gas mixture to an intermediate separative section, a final process heavy fraction may then be recovered from the upstream - end rotor element, for example, and a final process light fr~ction may be recovered as an axial discharge stream from the other end of the stacked turboseparative system.
Of course, many design variations are possible in resp~ct to the present invention, and several variations are shown in the upper right section of FIGURE 4 separated by dashed line 330. In the illustrated variation, the "scoop"
blade 334 does not have a knife-edse or s~immer defined opening, but instead is provided with a perm~able zone 332 '. ~ ' ' ~
~ I -28-", ~ .
.
~J~7Z04 .
along the curved surface. The zone 332, which is of a smooth, but microporous nature, permits passage of heavier gas there-~hrough from immediately adjacent the surface, but does not have a macroscopically rough surface which would generate excessively turbulent flow. The stator blade 336 may also be provided with means to separate and ~onduct therefrom a gas fraction, such as a knife-edge or skimmer defined opening, or a permeable ~one 338 As indicated, turboseparative apparatus of the type illustrated in FIGURES 1-4 may be particularly adapted for operation at speeds which are grossly subsonic with respect to the gas mixture to be separated, but which may be locally supersonic with respect to components of the mixture. In this connection, it is noted that sonic velocities decrease as a function of molecular weight, thereby decreasing the - xotational velocity which may be utilized before supersonic ~peeds are reached.- However, a~ligXter molecular weight gas, suoh as hydrogen, may be mixed with a heavier gas, such as UF6, to provide for increased7b~a~e velocity, and systems in w~ich the lighter fraction travels axially of the rotor ; elements are particularly adapted for such gas mixtures. The - lighter gas-"lubricant" may be readily separated from the ~inal light product stream and need not be separated at each :;
:: separative stage.
~5 It is-also desirable to provide methods and apparatus which may be particularly adapted for use at supersonic speeds, slnce various separative factorF are a function of operating ~' ~', . ' .
.1 .
.
' I -2g- . ' .
1~7204 speed. In a turboseparative unit, the highest speeds are prov~ded at the periphery of the rotating elements, and separative blade elements may be provided which are particularly adapted to be used at supersonic peripheral rotational speeds in respect of the gas mixture to be processed.
Illustrated in FIGURE 5 is a perspective view partially broken away of supersonic turboseparative apparatus 500 which comprises a plurality of axially stacked separative units internally of casing 502 supplied by gas manifold supply means 501, 503, 505. The separative units are shown in more detail in FIGURES 6 and 7 and comprise rotor means 507 having a plurality of deflector blade elements like element 602 regularly mounted in a radially symmetrical manner about the periphery of a rotating disc 504. Adjacent the deflector blade elements is a gas distribution ring which is employed to distribute gas to be processed into the path of the deflector blade units including units 601, 60 , 603. The ~` deflector blade units themselves are provided with curved surface bounded passageways which provide for lateral displace-ment of the gas at high velocity, and the consequent production of an impulse acceleration field ~in the illustrated embodiment, a number of such fields are produced) to provide a density gradient (several gradients in the illustrated embodiment) , 25 g~nerally in the direction of the field(s). The separative units also have means for dividing the gas in respect of its I density gradient(s) into fractions of different molecular ¦ weight.
'. , . , ..
~'~, . . ' , .' '.
-3Q- _ 11~7~04 In the apparatus 500, a relatively stationary qas mixture may be provided in a disc-chamber zone 605 defined by stationary disc walls 730, 732 which form a seal with shroud rings 604, 606 and which have means such as a perforated ring 607 to provide for feed gas entry. A
plurality of processing deflector blades may be rotatably mounted to rotate at supersonic speed into the path of admitted feed gas with a speed v~ = r2Q, where r2 is the radial distance of the blades from the axis of rotation; and o n is the rotational velocity. Because o~ the lateral curvature of the passageways of the deflector blades, feed gas which is intercepted by the deflector blades may be forced, or bent, laterally of the direction of rotation ~e.g., in a radial direction or in a direction parallel to the axis of rotation, or in a direction having both radial and axial components) to have a radial and/or axial speed vz or vr approximately that of v~ (e.g., v~ ~+v~) and bent, or accelerated, again in a generally opposite direction to substantially recover the lateral velocity component. During each bending, a por~ion of the higher molecular weight assay may be subtracted from - - the stream and fed in a cascade manner as input feed gas to another disc-chamber operating on a higher molecular weight mixture ~one stage up). The resultant lighter stream having the higher molecular weight cuts deleted therefrom may be ?s similarly fed to another disc-chamber operating on a lower molecular weight mixture (or.e stage down). The segregated heavier fractions may exit the deflector at high velocity, ' . 'I ' ' ', .
,_,1 j .
11~7Z~4 .
and the kinetic energy represented thereby may be used, for example, for the feed pressure. The lower molecular weight assay may exit with some portion of the rotational velocity due to frictional drag, or simply may exit with some velocity v~, vr, or v~ (where vz represents axial velocity, Vr repre-sents radial velocity, and v~ represents axial rotational velocity) by the particular design of the deflector, and this kinetic energy may also be utili~ed, for example, as feed pressure. Generally, the high rotational velocity of the - 10 deflector is usea to laterally accelerate the gas for a high lateral velocity, and a major portion of the energy of this lateral velocity may be recovered by channeling the gas to , ; accelerate ~he deflector in the direction of rota~ion. There may be a plurality, such as from about 3 to about 9 or more disc-chambers in the processing unit 500 with conventional cascaded matched flow interconnection.
The processing flow of a particular separation disc-chamber in the design of the illustrated embodiment is proportional to the width of the input opening of the individual deflector blades, which are illustrated in detail in FIGURES 6 and 7. FIGURE 6 is a side illustration of a deflector blade unit 602, which i9 bounded by an inner cylindrical shroud ring and seal unlt 604 and an outer . cylindrical shroud ring and seal unit 606. Identical i5 deflector blade units inclùding adjacent units 601, 603 are also regularly mounted between the shrouds 604, 606 to form the rotor unit. In the embodiment of FIGVRE 6, the deflector :, .
.
l ! . . .
~ i , .. .... ....... .
. . .
~ -32- ' . ...... . . ..
- 11~7ZO~
blade unit 602 is adapted to be rotated in a counterclockwise d~rection as shown by the directional arrow so that it (and the other blade units) will intercept gas admitted into its path through holes in the gas distribution ring. Gas inter-cepted by the deflector unit 602 is forced into the curvedopening 608 of the deflectox unit by the rotational motion.
The moving rotor divides the gas at a knife-edged central flow separator 610 positioned generally centrally within the .throat of the passageway 612. The gas is forced to travel through either laterally curved flow channel 614 or oppositely -curved flow channel 616, which are generally bilaterally symmetrical in respect of a cylindrical surface of rotation positioned centrally between the shroud rings 604, 606.
--Gas which is forced into the outer flow channel 614 . is abruptly laterally accelerated outwardly against curved -surface 618 by motion of the rotor element and curved surface blade unit 602. A higher molecular weight portion of this ; . outwardly accelerated flow is diverted by a knife-edge deflector or skimmer means 620 and conducted to a channel 622 which curves downwardly with respect to the plane of the illu~tration as shown by dashed line in FIGURE 7. Gas which is not diverted to channei 622 is forced by the rotational motion of the unit 602 to proceed along channel 624, where it i8 laterally accelerated inwardly by wall 626 having a I 25 curvature opposite of that of 618. A higher molecular weight ¦ portion of the laterally accelerated stream may be similarly ¦ - diverted to channel 628 which, like channel 626, bends ' ~ ' :' , ' . . , ' ' ..' ' , ~ 33_ .
... . ' ' ` ~
~ ~ ' . ' ' ~
~ ~ ~ ~ fi .
gradually into the plane of the drawing. The motion of the - deflector blade causes gas which is not deflected to channels 626 or 628 to be displaced relatively along channel 630 which is curved upwardly in the plane of the illustration. The central rear portion of the unit 602 is provided with an opening 632 which permits gas to be ; introduced into the zone sufficiently in advance of the next succeeding de~lector blade unit 603 to pro~ide for desired ~ distribution and amount of feed gas under operational 10 conditions of input gas, flow speed, deflector blade rotational speed, and deflector blade dimensions~ The lower siae of the deflector blade 602 is generally symmetrical with the previously described upper portion as shown in the drawings.
The construction of the deflector unit 602, portions of the adjacent side stationary disc elements 706, 710, and gas service means are shown in FIGURE 7, which is a partial ~ide cross.sectional view from the front of blade unit 602 as taken thxough line 6-6. Gas to be supplied to the deflector blade 602 is conducted from manifold 703 of manifold means 501 - and manifold 705 of manifold means 503 to input conduit 701 .
and conduit 707 to a ring shaped recess 704 in stationary disc element 706 and to a similar ring-shaped recess 708 in the other disc element 710. The recesses 704, 708 are provided i 25 with a gas permeable wall, which in the illustrated embodiment i8 ~ ring-shaped perforated sheet 607 in.a plane immediately ad~acent the side walls 714, 716 of the deflector blade unit ; . . ' ' '' ;,;' , ' . -34-., .
~' '` ' '~ , '' ' ' , ll~;)~ZO~
602. Deflector element channels 622 and 628, which are channels for a heavier molecular weight fraction, are ~axially) bent to dischar~e into recess 718 in order to divert and segregate this fraction upon motion of the deflector blade unit into the recess 718 and from there via conduit means 721 - ~ to manifold element 723. Similarly, the lighter fraction,-which is channeled in flow channel 630, is forced by motion of the deflector blade unit and the (axial) curvature of the channel 630 into recess 720 and from there via conduit means 725 to manifold element 727. The gas directed to recesses 718 and 720 has an axial and radial velocity component which may be converted to pressurq, and the pressurized gas may be conducted thereafter to become the respective input streams of subsequent cascaded processing disc-chambers, which may be located axially adjacent the illustrated disc-chamber. The inner channels of blade 602 are similarly diver~ed to recesses 729, 731. The multiple separation unit of apparatus 500 may be connected in suitable cascade manner by means of appropriate connection of the manifold means (such as means 501, 503, 505) of the respective separative units.
~ Illustrated in FIG~RE 8 is a partial side view of another embodiment 800 of a turboseparative apparatus deflector blade unit and the surrounding stationary sur~aces. The embodiment illustrated in FIGUR~ 8, has a deflector blade similar to that illustrated in FIGUgES 6 and 7, with the principal exception that the blade unit orientation has been rotated 90 so that the lateral displacement of the feed gas . ' . , .__"., ' " ' ' ' ' ! .
72~ .
is in an axial, rather than a radial, direction. In other variations, an intermediate blade orientation may be used having radial and axial components of displacement. In the embodiment of FIGURE 8, the outermost displaced higher S molecular weight stream lanalogous to the gas channeled in channel 628 of the embodiment of FIG~RE 6) is diverted axially to recesses 802, 804. The lighter molecular weight fraction of each side of the bilaterally symmetrical flow channels is diverted into recesses 806, 808, and the innermost higher molecular weight fraction (analogous to that of channel 622 of FIGURE 6), is similarly conducted to recess 814, 816.
The input gas to the separation zone to be inter-cepted by the deflector blade is introduced to recess 810 which is provided with a gas permeable wall such as a perforated cylindrical sheet 812 by means of supply conduit 820. The discharge flows to recesses 806, 808, 814, 816 are centrifugally pumped to those recesses, and a design element of centrifugal pumping from the rotational motion imparted to the processed gas channeled to recesses 802, 804 may be -- provided. The respective discharge flows may be conducted through the casing 822 of the stator element ~or appropriate subsequent treatment such as cooling, pressure energy utilization, etc~, and cascade interconnection. It is noted that the dif~erent high molecular weight cuts may be kept separate in this embodiment to enhance cascade effects.
l .
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The embodiment in FIGURE 8 is further illustrated in the cross-sectional side view of EIGURE 9, where it may be seen that the flow channels such as flow channel 302 of the deflector blade may be radially outwardly divergent in consideration of centrifugal gas motion.
- While various deflector blade units which produce lateral displacament of the feed gas in a radial direction and in an axial direction have been described, it will be app~eciated that deflector blade orientation.at intermediate positions may also be provided which produceS a combination of axial and radial accelexation. Furthermore, while specific ~eed gas supply and discharge gas configurations have been described, it will be appreciated that various other types of gas service designs may be utilized.
Illustrated in FIGURES 10 and 11 is another embodiment of separative apparatus 1000. A confined gas cloud introduced .~ into channel 1004 of rotary disc element 1006 will with an outwardly radial velocity component travelling radially on the . plane of a rotating disc 1002 tend to describe an Archimedean 1 20 spixal as a trajectory on the disc. Relative to the rest frame, - the gas does not have a velocity component in the vz and v~
directions. In the illustrated embodiment, a tube 1004 confining the gas is provided in the form of the "A spiral", so that gas introduced at the axis of the rotating disc slips by inside the tube with a high velocity v~ relative to the tube ¦ wall. A sudden displacement of the tube in a radial or axial ¦ direction at point 1006 bends the gas with supersonic velocity¦ . V~ 3 nr~ A portion of the hLgher molecular weight assay is . ! .
. .
. .
.
. . . . ~37~
' . - ' ' ; ', ~ .
?
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~ 7Z~
i~ substracted right after the bending, and there can be several bendings in the axial z direction for substractions as shown in FIGURE ll. The friction with the tube wall accelerates the gas in the v~ component which can be trans- -lated to a pressure energy for feed pressure and which may be recovered through use in accelerating the rotation of ~he disc as described previously. There can be many tubes mounted on a disc, and many discs Porm a processing unit.
- Control of degrading turbulence is relatively simple in this design as a bending t~be running into gas is used although there may be difficulties in maintaining a flow at high Mach number in this geometry.
While the present invention has been particularly described with respect to certain specific embodiments, it lS :will be appreciated that various modifications and adaptations may be made without departing from the spirit and scope of the present disclosure. For example, different variations of specific elements described in connection with one type of turboseparative apparatus may be adapted for use in connection with another type of turboseparative apparatus embodiment.
Thus, it will be appreciated that compound blade elements such as shown in connection with supersonic turboseparative apparatus and in which successive cuts of high and/or low molecular weight fractions may be made in cascade fashion within a rotor or stator unit for apparatus such as illustrated in FIGURES 1-4.
~ Furthermore, while in the illustrated embodiments, separation j is made ln respect of a density gradient having increasing ~''. . ' , "
' .. ' ' '~
., . . , ' . , . . . .
-38`~
... . . .
. - :
density in the direction of the applied centripetal field, another advantage may also be taXen of the lateral accelera-tion produced by the moving surface. In this connection, means, such as a suction slot or permeable diffusion surface (e.g., which might be located at numeral 51 of blade 30 in FIGURE 3 and connected via a longitudinal channel in the blade to a relative vacuum source acting at the radially interior end of the blade element) for taking in a portion of gas in the .wake of a moving surface or blade element, might be used to separate a lower molecular weight fraction which would preferably diffuse into the blade wake region under operating conditions. In another variation, the centrifugal pumping energy of gas in a separation zone not scooped into the : interior of a blade may be recycled to the system, as well as that scooped into the blades. Such modifications and adapta-tions are intended to be included within the scope of the invention as defined in the following claims.
,Various of the features of the invention are set foxth in the following claims.
.
~, - ' ' " ' . ~: .
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. ~ . - _~9_ . ___ :, '
Claims
1. A turbomechanical method for separating a gas mixture of different molecular weight components, on the basis of molecular weight of the components of the mixture, comprising the steps of introducing the gas mix-ture into a separation zone, rotatably forcing a plurality of curved-surface blades into the gas mixture in the sep-aration zone to accelerate the gas laterally of the direc-tion of motion of the blades under non-turbulent flow conditions, said acceleration being along the axis of ro-tation of the blades, and to produce a density gradient in the laterally accelerated gas adjacent the curved sur-faces of the blades forced into the gas mixture, and separating a higher molecular weight fraction of said laterally accelerated gas immediately adjacent the curved surfaces of said blades to provide higher and lower molecular weight gas fractions by diverting said higher molecular weight gas fraction immediately adjacent the surfaces of said blades to the respective interiors of said blades through smooth, porous zones of said curved blade surfaces.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US70893976A | 1976-07-27 | 1976-07-27 | |
| US708,939 | 1976-07-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1107204A true CA1107204A (en) | 1981-08-18 |
Family
ID=24847784
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA283,530A Expired CA1107204A (en) | 1976-07-27 | 1977-07-26 | Methods and apparatus for gaseous separation |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1107204A (en) |
-
1977
- 1977-07-26 CA CA283,530A patent/CA1107204A/en not_active Expired
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