WO2017133791A1

WO2017133791A1 - Gas separating centrifuge

Info

Publication number: WO2017133791A1
Application number: PCT/EP2016/052537
Authority: WO
Inventors: Franz Strohmer; Christian Topf; Luis SEMPERE-BELDA; Andreas Paul FRÖBA; Michael Heinrich RAUSCH; Tobias Klein
Original assignee: Areva Gmbh; Friedrich-Alexander Universität Erlangen-Nürnberg
Priority date: 2016-02-05
Filing date: 2016-02-05
Publication date: 2017-08-10

Abstract

The invention relates to a separating device (2) for separating a first and a second component of a mixture, comprising a housing (4) with a cylindrical housing part (6), an upper lid (8) and a lower lid (10) forming a separating chamber (12) there between, further comprising a rotor (14) being rotatable arranged within the housing (4), further comprising at least one inlet port (24) being provided in the housing (4) for supplying the mixture to the separating chamber (12), further comprising at least one first outlet port (26) for discharging the first component of the mixture and at least one second outlet port (28) for discharging the second component of the mixture, each being provided in the housing (4), further comprising a separation wall (30) being arranged within the housing (4), whereby at least the lower lid (10) and the cylindrical housing part (6) are integrally formed.

Description

GAS SEPARATING CENTRIFUGE

Description

The invention relates to a separating device for separating components of a mixture, in particular a separating device for separating components of a gas mixture respectively a gas centrifuge.

DE 195 43 106 Al discloses a centrifuge that comprises a housing, a rotor being attached to a shaft and a drive that is e.g . coupled to the shaft by means of a magnetic coupling. The rotor is sealed against the drive by means of a separation element. The upper end of the housing can be closed by means of a removable upper lid.

DE 10 2009 053 660 B3 discloses a gas centrifuge comprising several cylinders being arranged concentrically within the housing of the gas centrifuge. The housing comprises a collecting container for the separated gas, an upper lid and a lower lid. The gas mixture is transported through the cylinders outwardly towards the sheath of the rotor, light and heavy materials are separated, and the heavy materials are collected in the collecting container. The known gas centrifuges comprise several components and housing parts made of different materials, so that their manufacture is time-consuming and cost-intensive. It is an object of the invention to provide a separating device, in particular a gas centrifuge that can be manufactured easily and in a cost-effective manner in comparison with known separating devices respectively gas centrifuges.

The object is achieved by a separating device having the features according to claim 1. The separating device for separating a first and a second component of a mixture comprises a housing with a cylindrical housing part, an upper lid and a lower lid forming a separating chamber between them. The separating device further comprises a rotor being rotatable arranged within the housing respectively within the separating chamber. The housing is provided with at least one inlet port for supplying the mixture into the interior of the housing, respectively into the separating chamber, and at least one first outlet port for discharging the first component of the mixture and at least one second outlet port for discharging the second component of the mixture. A separation wall is arranged within the housing, especially in a lower part of the housing, thus close to the lower lid, in order to prevent a re-mixing of the separated components by turbulences. At least the lower lid and the cylindrical housing part are integrally formed.

As the lower lid and the cylindrical housing part are integrally formed, manu- facturing of the separating device is simplified as less components are needed and the separating device has a more simple construction. At least the cylindrical housing part and the lower lid may for example be manufactured by twisting or milling automatically in one single step during the manufacturing process.

The separating device is used to separate components of a mixture, in particular a gas mixture. It is in particular used during a disposing and recycling process of a radioactive contaminated component, in particular for disposing and recycling of a graphite moderator. During such a process, the graphite moderator is removed from a nuclear power plant and cutted into small pieces which are subsequently incinerated at high temperatures for forming a gas mixture containing mainly radioactive carbon monoxide ¹⁴CO and non-reactive carbon monoxide ¹²CO. The carbon monoxide gas mixture is subsequently treated in a separating device according to the invention for separating radioactive carbon monoxide ¹⁴CO and non-reactive carbon monoxide ¹²CO from each other. Nevertheless the separating device can be used for separating different components of any other gas mixtures, e.g. it is also possible to separate nitrogen and oxygen from air. The separating device could therefore be used to enrich e.g. oxygen in breathing air, forming Nitrox gas mixture for scuba diving, or oxygen in air that is delivered to a carburator inlet for car engines in order to increase the power or lower the nitric gas emission of a motor respectively engine during the fuel burning process.

The rotor is preferably rotatable arranged on a shaft within the housing, whereby the shaft is coupled to a drive device that is arranged outside of the housing. The shaft is in particular coupled to the drive device by means of a magnetic coupling. In this case no opening has to be provided in the upper lid for rotating the shaft, so that fluid tightness of the housing respectively the separating chamber is ensured and leakage that may be caused if the shaft must be carried through an opening in the upper lid is prevented . This is in particular advantageous if toxic or radioactive gas mixtures are separated with the separating device.

In a preferred embodiment the at least one inlet port is provided in the upper lid of the housing and/or the at least one first outlet port is provided in the lower lid and in an area within the separation wall and/or the at least one second outlet port is provided in the cylindrical housing part. In the case of sepa- rating radioactive carbon monoxide ¹⁴CO and non-reactive carbon monoxide ¹²CO from each other during a disposing and recycling process of a graphite moderator, the heavier radioactive carbon monoxide ¹⁴CO is collected at an inner surface of the cylindrical housing part and is therefore removed through the second outlet ports, the lighter non-reactive carbon monoxide CO is collected within the separation wall and is therefore removed through the first outlet port. The second outlet ports are preferably provided in a lower area of the cylindrical housing part, this means in an area which is below an end por- tion of the separation wall.

According to further preferred embodiment the housing is provided with several, in particular four inlet ports and/or several, in particular four first outlet port and/or several, in particular four second outlet ports that are arranged symmetrically around a central longitudinal axis of the housing. This has the advantage that turbulences within the separating chamber are reduced. The several inlet and outlet ports are preferably arranged symmetrically around a longitudinal axis of the housing.

In order to further reduce the number of components, the separation wall is preferably also integrally formed with the lower lid and therefore also integrally formed with the cylindrical housing part. Therefore most components of the separating device can be easily and cost-effective manufactured in one manufacturing step, for example by twisting or milling.

In a preferred embodiment, the separation wall is formed as a cylindrical wall that extends coaxially and parallel to the longitudinal axis of the housing starting from the lower lid. Thus the separation wall is formed in a lower part of the housing close to and integrally formed with the lower lid and extends towards the upper lid. As the separation wall is formed as a cylindrical wall, it surrounds the longitudinal axis of the housing in an axial section which adjoins the lower lid, completely, what allows a reliable separation of the gas components. The separation wall may extend so far into the separating chamber that it overlaps with the rotor arranged within the housing respectively the separating chamber. Such an arrangement ensures that a renewed mixing of the different gas components is avoided in an area below the rotor. In order to allow a free rotation of the rotor that comprises in particular at least two rotor blades, each of the rotor blades is provided with a recess, into which the separation wall extends. The recesses are therefore provided in an area of the rotor that faces the lower lid. The rotor blades are arranged in peripheral direction in uniform distances, for example if there are three rotor blades they are arranged in an angle of 120° to each other.

In order to connect the parts of the housing to form the separating chamber, in particular to fix the upper lid to the cylindrical housing part, the housing respectively the cylindrical housing part is provided with a flange that is integrally formed at an upper end of the cylindrical housing part. The flange extends outwardly from the cylindrical housing part in a radial direction forming an almost right angle with an outer surface of the cylindrical housing part. The upper lid and the flange are connected to each other by known connection techniques, for example by bonding, by welding or by means of a screw connection. The upper lid has a larger diameter than the cylindrical housing part and the lower lid and it lies flat on the front side of the cylindrical housing part, preferably on the flange so that it can be connected to the cylindrical housing part in an easy way

To prevent gas leakage from the separating chamber and into the environment, the separating chamber respectively the housing of the separating device comprises sealing devices. In a preferred embodiment, the upper end respectively a front side of the upper end of the cylindrical housing part, prefer- ably the flange that is facing the upper lid is provided with a circular groove, wherein a sealing element is arranged. In particular the sealing element is a circular sealing ring.

In order to avoid turbulences within the separating chamber and near the ro- tor, the separating device comprises preferably at least one perforated plate that is arranged within the housing respectively the separating chamber below or above the rotor or also on both sides of the rotor. The perforated plate functions as a flow straightener and turbulences that are caused by supplying the mixture or by discharging the components of the mixture and would have negative influence on the separation process are reduced significantly.

The perforated plate can be designed such that it firmly fixes within the hous- ing, but in this case dimensions of the perforated plate and the housing have to match precisely what is work-intensive to manufacture. Therefore in a preferred embodiment, the housing comprises at least one supporting means for supporting the at least one perforated plate. Preferably the supporting means are formed by at least one projection that is integrally formed with the hous- ing. For supporting a perforated plate that is arranged above the rotor, the supporting means respectively the projection may be arranged at an inner surface of the cylindrical housing part. For supporting a perforated plate that is arranged below the rotor, the supporting means respectively the projection are in particular arranged at an inner surface of the separation wall. The support- ing means respectively the projection is preferably formed as a circular projection that extends completely around and along the inner surface. Such supporting means have the advantage that the perforated plate can easily be placed on the supporting means without considering the exact dimensions, what reduces the effort in manufacturing .

In a preferred embodiment, a lower end of the shaft is mounted in an axial tapered roller bearing. Lower end of the shaft refers to that end of the shaft that faces towards the lower lid . Such a bearing carries the weight of the shaft and the rotor and stabilizes them laterally. This has the advantage that narrow gaps between the separation wall, the housing and the rotor can be reached. The axial tapered roller bearing may also be integrally formed with the lower lid, the cylindrical housing part and optionally the separation wall .

According to a further preferred embodiment, an upper end of the shaft is mounted in a cylindrical roller bearing. Upper end of the shaft refers to that end of the shaft that faces towards the lower lid. The cylindrical roller bearing stabilizes the rotor laterally even if an elongation of the rotor due to thermal heating occurs during operation although the gas mixture is cooled. In order to be able to rotate the rotor by means of a magnetic coupling, the upper lid is particularly made of plastics, preferably made of polypropylene. In particular if toxic components, for example radioactive carbon monoxide ¹⁴C, are treated, it is necessary to reach absolute gas tightness. An upper lid made of plastics allows a magnetic drive for the shaft so that no openings for leading the shaft through the upper lid have to be provided and leakages are therefore prevented constructively. It is also advantageous if the cylindrical housing part, the lower lid and the separation wall are made of austenitic or stainless steel. Also the rotor blades and the perforated plates are advantageously made of austenitic or stainless steel . These materials can be allow an easy cleaning or decontamination step after a separation process what is in particular advantageous if radioactive gas components have been treated. Furthermore such materials show a high corrosion resistance and best conditions for machining, for example twisting or milling, that is carried out in the manufacturing process of the separating device. In order to further simplify such cleaning or decontamination steps, in a further preferred embodiment, the surfaces of said components, namely the cylindrical housing part, the lower lid and the separation wall are polished , in particular electro polished and show a surface roughness smaller than 0,5 μιτι. Thus already an adhering of radioactive components on the inner surfaces of the separating device during operation of the separating device is reduced . The invention will be described more fully hereinafter with reference to the accompanying drawings, in which

FIG 1 shows a separating device in a longitudinal section, FIG 2 shows a top view of the separating device below the cutting plane I-I of Fig . 1. Fig . 1 shows a separating device 2, for separating a first and a second component of a mixture, in particular a gas centrifuge that may be used for separating radioactive carbon monoxide ¹⁴CO and a non-reactive carbon monoxide ¹²CO of a carbon monoxide gas mixture. The separating device 2 comprises a housing 4 having an elongated cylindrical housing part 6, an upper lid 8 and a lower lid 10. The housing parts form a separating chamber 12 between them in which the components of the gas mixture are separated from each other. Therefore a rotor 14 is rotatable arranged within the housing 4 respectively within the separating chamber 12. The rotor 14 is rotatable arranged on a shaft 18 that is also arranged within the housing 4 and extends along a central longitudinal axis M of the housing 4. The shaft 18 extends from the upper lid 8 to the lower lid 10 and is coupled with its upper end, thus its end that faces the upper lid 8, to a drive device 20 that is arranged outside of the housing 4. The coupling is realized by means of a magnetic coupling 22, so that is not necessary to provide an opening in the upper lid 8 and fluid tightness of the separating chamber 12 is ensured.

The separating device 2 respectively the housing 4 further comprises four inlet ports 24 that are provided in the upper lid 8 of the housing 4 for supplying the gas mixture to the separating chamber 12. Furthermore, four first outlet ports 26 are provided in the lower lid 10 of the housing 4 in an area within a separation wall 30 for discharging the first component, thus a gas flow containing the lighter non-reactive carbon monoxide ¹²CO of a carbon monoxide gas mixture, from the separating chamber 12 after the separation process. Four sec- ond outlet ports 28 are provided in the cylindrical housing part 6 of the housing 4 for discharging the second component of the gas mixture, thus a gas flow containing the heavier radioactive carbon monoxide ¹⁴CO of the carbon monoxide gas mixture that is collected at an inner surface of the cylindrical housing part 6 and is moving downwards, from the separating chamber 12. Due to the longitudinal section view, only two inlet ports 24, two first outlet ports 26 and two second outlet ports 28 can be seen in Fig. 1. The inlet ports 24, the first outlet ports 26 and the second outlet ports 28 are arranged symmetrically around the central longitudinal axis M of the housing 4, as can be seen exemplary for the second outlet ports 28 in Fig. 2. In the case of four inlet respectively outlet ports, the ports are offset from each oth- er by an angle of 90°.

In order to allow discharging the components of the gas mixture separated from each other from the separating chamber, the separating device 2 respectively the housing 4 is provided with a separation wall 30 that is arranged within the housing 4. In order to simplify the manufacturing of the separating device 2, the separation wall 30 is integrally formed with the lower lid 8. The separation wall 30 is formed as a cylindrical wall 32 that extends coaxially and parallel to the longitudinal axis M of the housing 4 starting from the lower lid 8. The heavier radioactive carbon monoxide ¹⁴CO accumulates at an inner sur- face 54 of the cylindrical housing part 6, the lighter non-reactive carbon monoxide ¹²CO accumulates at an inner surface 48 of the separation wall 30.

The lower lid 10, the cylindrical housing part 6 and the separation wall 30 are integrally formed and are made of stainless steel . Even the rotor 14 is made of stainless steel . The surfaces of the cylindrical housing part 6 and of the lower lid 10, more precisely the inner surface 54 of the cylindrical housing part 6 and an inner surface 56 of the lower lid 10, and the surfaces of the separation wall 30 are electropolished so that they show a surface roughness smaller than 0,5 μιτι. This has the advantage that less of the radioactive particles being present in the gas mixture adhere to the surfaces of the separating device 2. This would in turn simplify subsequent cleaning or decontamination process that have to be carried out before appropriate disposal of the components of the separating device 2. The rotor 14 comprises three rotor blades 16 that are arranged in uniform distance so that two rotor blades 16 form an angle of 120° between them, as can best be seen in Fig. 2. The cylindrical separation wall 30 and the rotor blades 16 overlap in a lower part of the rotor 14. Therefore each of the rotor blades 16 is provided with a recess 34 on its lower end in which the cylindrical separation wall 30 extends, so that rotation of the rotor 14 can be easily enabled .

The housing 4 is provided with a flange 36 that is integrally formed at an up- per end of the cylindrical housing part 6. The flange 36 extends in a radial direction at a right angle to the surfaces of the cylindrical housing part 6. The flange 36 is provided with a circular groove 38. A circular sealing element 40 is arranged in the groove 38 for sealing a possible gap between the cylindrical housing part 6 and the upper lid 8 and therefore sealing the separating cham- ber 12 against the environment. The upper lid 8 has a larger diameter than the cylindrical housing part 6 and the lower lid 10, so that it can be fixed to the flange 36 in a known manner, e.g. by means of a screw (not shown) or by bonding. The upper lid 8 is made of polypropylene so that the shaft 18 can be coupled to the drive device 20 by means of a magnetic coupling 22.

In order to avoid turbulences in the separating chamber 12 that may have negative effects on the separation process, the separating device comprises two perforated plates 42. The first perforated plate 42 is arranged within the housing 4 above the rotor 14, the second perforated plate 42 is arranged with- in the housing below the rotor 14 and within the cylindrical separation wall 30. The cylindrical housing part 6 comprises supporting means 44 in the form of a cylindrical projection 46 being integrally formed at the inner surface 42 of the cylindrical housing part 6 on which the first perforated plate 42 can be mounted. For supporting the perforated plate 42 that is arranged below the rotor 14, the inner surface 48 of the separation wall 30 is provided with supporting means 44 that are formed as circular projection 36 and integrally with the separation wall 30 as well.

A lower end of the shaft 18 is mounted in an axial tapered roller bearing 50, an upper end of the shaft 18 is mounted in a cylindrical roller bearing 52. The bearings stabilize the shaft 18 laterally and balance elongations of the shaft 18 that may be caused by thermal heating during the separating process. References

2 Separating device 36 flange

4 housing 38 circular groove

6 cylindrical housing part 40 sealing element

8 upper lid 42 perforated plate

10 lower lid 44 supporting means

12 separating chamber 46 projection

14 rotor 48 inner surface of the separa-

16 rotor blade tion wall

18 shaft 50 axial tapered roller bearing

20 drive device 52 cylindrical roller bearing

22 means of magnetic coupling 54 inner surface of the cylindri-

24 inlet port cal housing part

26 first outlet port

28 second outlet port

30 separation wall M central longitudinal axis

32 cylindrical wall

34 recess

Claims

1. Separating device (2) for separating a first and a second component of a mixture, comprising

- a housing (4) with a cylindrical housing part (6), an upper lid (8) and a lower lid (10) forming a separating chamber (12) between them,

- a rotor (14) being rotatable arranged within the housing (4),

- at least one inlet port (24) being provided in the housing (4) for supplying the mixture to the separating chamber (12),

- at least one first outlet port (26) for discharging the first component of the mixture and at least one second outlet port (28) for discharging the second component of the mixture, each being provided in the housing (4),

- a separation wall (30) being arranged within the housing (4),

characterized in that

at least the lower lid (10) and the cylindrical housing part (6) are integrally formed.

2. Separating device (2) according to claim 1, characterized in that the rotor (14) is rotatable arranged on a shaft (18) within the housing (4), whereby the shaft (18) is coupled to a drive device (20) that is arranged outside of the housing (4), whereby the shaft (18) is preferably coupled to the drive device (20) by means of a magnetic coupling (22).

3. Separating device (2) according to any of the preceding claims, characterized in that the at least one inlet port (24) is provided in the upper lid (8) of the housing (4) and/or the at least one first outlet port (26) is provided in the lower lid (10) and in an area within the separation wall (30) and/or the at least one second outlet port (28) is provided in the cylindrical housing part (6).

4. Separating device (2) according to any of the preceding claims, characterized in that the housing (4) comprises several inlet ports (24) and/or several first outlet ports (26) and/or several second outlet ports (28) that are arranged symmetrically around a central longitudinal axis (M) of the housing (4).

5. Separating device (2) according to any of the preceding claims, characterized in that the separation wall (30) is integrally formed with the lower lid (8).

6. Separating device (2) according to any of the preceding claims, characterized in that the separation wall (30) is formed as a cylindrical wall (32) that extends coaxially and parallel to the longitudinal axis (M) of the housing (4) starting from the lower lid (8).

7. Separating device (2) according to any of the preceding claims, characterized in that the rotor (14) comprises at least two rotor blades (16) each being provided with a recess (34), whereby the separation wall (30) extends in these recesses (34).

8. Separating device (2) according to any of the preceding claims, characterized in that the housing (4) is provided with a flange (36) being integrally formed at an upper end of the cylindrical housing part (6) and extending outwardly in a radial direction.

9. Separating device (2) according to any of the preceding claims, characterized in that an upper end of the cylindrical housing part (6) is provided with a circular groove (38), wherein a sealing element (40) is arranged.

10. Separating device (2) according to any of the preceding claims, characterized in that it comprises at least one perforated plate (42) being arranged within the housing (4) and below and/or above the rotor (14).

11. Separating device (2) according to any of the preceding claims, characterized in that the housing (4) comprises at least one supporting means (44) for supporting the at least one perforated plate (42).

12. Separating device (2) according to claim 11, characterized in that the supporting means (44) are formed by at least one projection (46) that is integrally formed with the housing (4).

13. Separating device (2) according to any of the claims 11 or 12, characterized in supporting means (44) being arranged at an inner surface (48) of the separation wall (30).

14. Separating device (2) according to any of the preceding claims, characterized in that a lower end of the shaft (18) is mounted in an axial tapered roller bearing (50) and/or an upper end of the shaft (18) is mounted in a cylindrical roller bearing (52).

15. Separating device (2) according to any of the preceding claims, characterized in that the upper lid (8) is made of plastics, preferably made of polypropylene.

16. Separating device (2) according to any of the preceding claims, characterized in that at least the cylindrical housing part (6), the lower lid (10) and the separation wall (30) are made of austenitic or stainless steel .

17. Separating device (2) according to any of the preceding claims, characterized in that the surfaces of the cylindrical housing part (6), the lower lid (10) and the separation wall (30) are polished and show a surface roughness smaller than 0,5 μιτι.