Patent Number: 047568763
Section: description

The drawing shows the containment 1 of the modular device which consists of walls 2 of great thickness made of lead, covered on ther inner faces with a steel sheet 3. The containment 1 comprises a side wall 2a and a bottom 2b which are connected to one another so as to form a shaft of vertical axis ZZ', the bottom of which is closed in a leak-proof manner by means of the sheets 3 covering the walls 2a and 2b. Reinforced angle pieces 5 are fastened to the edges of the bottom 2b, to constitute the supports of the modular ultrafiltration device. These angle pieces are perforated with holes making it possible to fasten the device on a supporting surface 6 by means of screws. The orifice located in the upper part of the containment 1 is closed by means of a cover 7. Inside the containment 1, the ultrafilter 15 is retained by means of an assembly of beams 50 arranged radially and fastened on the one hand to the outer wall of the casing 8 of the ultrafilter and on the other hand to the steel sheet 3 covering the inside of the containment 1; the dimensions of these beams make it possible to absorb forces, such as those generated by a seismic shock or in the event of an accident of any kind. The casing 8, which is symmetrical in terms of revolution and which is arranged in the containment 1 with its axis coinciding with the axis ZZ', comprises a cylindrical central part, integral with a connecting flange 9 of great thickness, and a rounded bottom. The casing 8 contains an ultrafiltration assembly 10 which can be introduced into this containment 8 or removed via its upper orifice 8a. Three connection pieces pass through the wall of the casing 8: an inlet connection piece 12 for water to be purified and a concentrateoutlet connection piece 14, both in the upper part of the casing, and a filtrate-outlet connection piece 16 in the lower part of the casing 8. The connection pieces 12 and 16 pass through the side wall 2a of the containment 1 in a leak-proof manner by means of a metal membrane 51 welded, on the one hand, to the inner wall 3 of the containment and, on the other hand, to the corresponding connection piece, and on the outside of the containment 1 are integral with connecting flanges 13 and 17, respectively. There will now be a brief description of the ultrafiltration assembly 10 and its arrangement inside the casing 8, the ultrafilter 15 consisting of the casing 8, its connection pieces and the elements arranged inside the casing 8 being of a new type described in a patent application filed on the same day as the present application. The ultrafiltration assembly 10 consists of a cylindrical casing 11 with a rounded bottom, inside which is placed the ultrafiltration wall consisting of an assembly of vertical tubes 18, the ends of which are fastened on the inside of two tube plates 19 and 20 respectively. The upper tube plate 20 is machined on its periphery to form a groove which receives an O-ring gasket 52 interacting with a gasket bearing surface 53 attached to the inner surface of the casing 8. Centering pieces 54 integral with the inner surfaces of the casing 8 ensure that the casing 11 is retained transversely. The rounded bottom of the casing 11 bears on the bottom of the casing 8 by means of a spring 55. Arranged above the plate 20 is a partitioning 21 which makes it possible to delimit several compartments in the inner volume of the casing 8 above the plate 20. In the same way, a partitioning 22 makes it possible to delimit several compartments in the part of the casing 11 located underneath the tube plate 19. The ultrafilter 15 operates as follows: The water to be purified is introduced into the casing 8 via the connection piece 12, inside one of the compartments delimited by the partitioning 21. The water to be purified penetrates into the ultrafiltration tubes and then circulates inside these tubes 18 in one direction and then the other as a result of the relative arrangement of the partitionings 21 and 22. The liquid circulating in the tubes 18 constitutes the concentrate, the impurity content of which increases, and filtrate consisting of pure water passes through the walls of the tubes and enters the inner volume of the casing 11 between the tube plates 19 and 20. A partitioning (not shown) also allows the filtrate to circulate in this space of the ultrafiltration assembly. The last compartment in the circulation of the filtrate communicates via an orifice passing through the casing 11 with the space provided between the casings 8 and 11. The filtrate is discharged through the connection piece 16 which communicates with the space. The last compartment arranged in the circulation of the concentrate and above the plate 20 communicates with the concentrate-outlet connection piece 14. A pump 25 for circulating the water to be purified and the concentrate is fastened to the removal cover 7 of the containment 1. This pump incorporates a connecting flange 26 matching the flange 9 of the ultrafilter 15. the flanges 9 and 26 have holes in matching positions for the passage of bolts or fastening screws. A gasket 27 is inserted between the two flanges during assembly, with the result that the pump 25 and its flange 26 ensure the leak-proof closure of the upper part of the casing 8. The pumping and circulation of the concentrate are carried out by means of the pump 25, of which the necessary junctions with the corresponding compartments delimited by the partitioning 21 are provided. Holes 29 pass through the cover 7 in line with the fastening screws of the flanges 9 and 26, to allow these flanges to be fitted and removed. The pump 25 is cooled by a cooling fluid penetrating into the pump housing via a pipeline 30. Lifting rings 31 and 32 respectively are fastened to the containment 1 and to the pump 25, thus making it possible either to transport the molded assembly by means of the rings 31 or to transport the pump 25 by means of the rings 32 and gain access to the tube bundle. A cylindrical heat exchanger 32 with a rounded bottom, making it possible to cool the concentrate, is mounted inside the containment 1. The concentrate-outlet connection piece 14 penetrates in a leak-proof manner inside the casing of the heat exchanger 32, where it is connected to an exchange tube, the other end of which is connected to a concentrate-discharge connection piece 35. The connection piece 35 passes through the containment 1 so as to be connected on the outside of this containment 1 to a connecting flange 36. Cooling fluid is introduced into the casing of the exchanger 32 via a connection piece 37 and is recovered via a connection piece 39, and the connection pieces 37 and 39, because of welded sealing membranes 51, pass in a leak-proof manner through the side wall 2a of the containment 1, to be connected outside this containment to connecting flanges 38 and 40, respectively. A heat-insulating material in divided form 41 fills the free volume of the containment 1 outside the elements located within this containment 1. The modular ultrafiltration device just described can be mounted very easily inside the containment shell of a nuclear reactor, for example in order to be arranged on an ultrafiltration loop taken off from an auxiliary primary-fluid treatment circuit, to constitute an ultrafiltration circuit of a new structure, such as that described in a patent application filed on the same day as the present application. All that is necessary, in fact, is to place the modular ultrafiltration device at the desired location by using a lifting means attached to the rings 31. The module is subsequently secured in place by means of its supports 5. The connection pieces are then connected up, by means of the corresponding connecting flanges, to the corresponding pipes provided for this purpose. The module, assembled in the way shown in the drawing, incorporates all the necessary active elements of the ultrafiltration loop and can be connected to the auxiliary primary-fluid treatment circuit purely by means of passive elements. It is quite clear that the modular device can be removed very simply and very quickly, and the module as a whole provides biological protection because of the very thick lead walls 2. Furthermore, the modular device in itself provides good thermal insulation for its elements, in which the primary water circulates, by means of the material in divided form 41. On the other hand, one of the essential advantages of the modular device according to the invention is that it makes it possible to separate and extract the ultrafiltration assembly easily, in order to service it, repair it or replace its tubular ultrafiltration wall. All that is necessary for this purpose, in fact, is to separate the flanges 9 and 26 from outside the containment 1 and then lift the cover 7 and the flange 26 by means of the ring 32 of the pump 25, to gain access to the inner part of the casing 8 containing the partitioning 21 and the ultrafiltration assembly 10. The filter can be refitted very easily and very quickly by means of operations carried in reverse order to the removal operations, for example after the ultrafiltration assembly 10 has been replaced. The invention is not limited to the embodiment which has been described. The thick-walled containment can be made in a different form, and the components constituting the module can be placed in different respective arrangements. For example, the arrangement of the ultrafilter 15 can be completely reversed, the liquid to be purified entering in its lower part and the filtrate being discharged in its upper part. Finally, the modular ultrafiltration device according to the invention can be used in any nuclear reactor, the cooling liquid of which is at a high temperature and a high pressure.