METHOD FOR MANUFACTURING A GENERALLY CURVED HEAT EXCHANGER MODULE WITH AT LEAST ONE LIQUID CIRCUIT; HEAT EXCHANGER WITH MULTIPLE CURVED HEAT EXCHANGER MODULES MANUFACTURED USING THE METHOD

Description

technical field

[0001] The present invention relates to heat exchanger modules with at least one fluid circuit, preferably with at least two fluid circuits, comprising at least one conduit. The invention relates more particularly to a new manufacturing method for such heat exchanger modules to give them a generally curved shape.

[0002] A curved plate heat exchanger module is known from US document 2007 / 023174 A1.

[0003] Known heat exchangers comprise either one or at least two internal fluid circulation channels. In single-circuit exchangers, heat exchange occurs between the circuit and a surrounding fluid in which it is immersed, or with an element from which heat must be supplied or extracted, such as in molds. In exchangers with at least two fluid circuits, heat exchange occurs between the two fluid circuits.

[0004] Chemical reactors are known to operate a continuous process in which a small quantity of co-reactants is simultaneously injected into the inlet of a first fluid circuit, preferably equipped with a mixer, and the resulting chemical product is recovered at the outlet of this first circuit. Among these known chemical reactors, some include a second fluid circuit, usually called a utility circuit, whose function is to thermally control the chemical reaction, either by supplying the heat necessary for the reaction or, conversely, by removing the heat released by it. Such chemical reactors with two fluid circuits and a utility circuit are usually called heat exchanger-reactors.

[0005] The present invention relates both to the implementation of heat exchangers with a sole function of heat exchange and to the implementation of reactor-exchangers. Therefore, the term "heat exchanger with at least one fluid circuit" should be understood, within the scope of the invention, to include both a heat exchanger with a sole function of heat exchange and a reactor-exchanger.

[0006] A heat exchanger module according to the invention can also be implemented in any other application requiring an exchange between two fluids, such as a liquid and a gas, or two liquids or even two gases, in particular when rapid and / or large amplitude temperature variations are involved.

[0007] For the purposes of this invention, "primary fluid" means the usual meaning in thermal engineering, namely the hot fluid which transfers its heat to the secondary fluid which is the cold fluid.

[0008] Conversely, in the context of the invention, "secondary fluid" is understood in the usual sense in thermal engineering, namely the cold fluid to which heat is transferred from the primary fluid.

[0009] Although described with reference to a preferred application of heat exchanger of an SMR type nuclear reactor (“Small Modular Reactor” in Anglo-Saxon terminology), the invention can be implemented in all applications requiring heat exchangers, in particular to be integrated into a cylindrical tank.

[0010] Among these applications, we can mention high-temperature electrolyzers (HTE, or HTSE, or High Temperature Steam Electrolysis) with solid oxides (SOEC, or "Solid Oxide Electrolyzer Cell"), exchangers in the chemical and petrochemical industry, steam generators, and integrated SMR type nuclear reactors. Previous technique

[0011] Existing plate heat exchangers offer significant advantages over existing tube heat exchangers, particularly in terms of thermal performance and compactness due to a favorablely high surface area to heat exchange volume ratio.

[0012] Examples of known tube-and-shell heat exchangers include shell-and-tube heat exchangers, in which a bundle of straight or U-shaped or helical tubes is mounted on perforated plates and arranged inside a shell-and-tube enclosure. In these shell-and-tube heat exchangers, one fluid flows inside the tubes while the other flows inside the shell. These shell-and-tube heat exchangers have a large volume and are therefore not very compact.

[0013] The known plate heat exchangers are more compact and are obtained by stacking plates with channels and assembling them together.

[0014] Similarly, plate heat exchanger reactors offer the advantage of high compactness and high cooling capacity, thus providing excellent thermal control during chemical reactions. These reactions are often exothermic, and it is necessary to limit the temperature rise in the reactive channels, i.e., where the chemical reaction takes place, in order to control the reaction from both a thermal and chemical perspective, and also to limit the thermal aging of the catalysts sometimes present in the reactive channels.

[0015] In all cases, the channels are generally made by stamping plates, sometimes by adding folded strips in the form of fins or by machining grooves. Machining is carried out mechanically, for example by milling, or chemically. Chemical machining is usually called chemical or electrochemical etching. The purpose of assembling the plates is to ensure the sealing and / or mechanical strength of the heat exchangers, particularly their resistance to the pressure of the fluids circulating inside. The assembly generally involves a stack made by superimposing, according to a regularly repeated sequence, plates of several types, each type corresponding to one of the fluid circuits. The stack may contain ungrooved separation plates.

[0016] Several assembly techniques are known and are implemented depending on the type of plate heat exchanger desired.

[0017] The plates can be assembled mechanically, using tie rods to maintain a tight stack between two thick, rigid plates positioned at the ends. The channels are then sealed by compressing gaskets. Assembly can also be achieved by welding, generally limited to the periphery of the plates. This sometimes requires inserting the heat exchanger into a shell after welding to ensure it can withstand the fluid pressure.

[0018] The assembly can still be achieved by brazing, particularly for heat exchangers to which fins are added.

[0019] The assembly can finally be obtained by diffusion welding (diffusion welding).

[0020] The last two techniques mentioned allow for the production of heat exchangers with particularly high mechanical strength. Indeed, thanks to these two techniques, the assembly is achieved not only at the periphery of the plates but also inside the exchanger.

[0021] Heat exchangers with plates assembled by diffusion welding have even more mechanically efficient seals than the seals of exchangers obtained by brazing due to the absence of the filler metal required for brazing.

[0022] Diffusion welding involves creating a solid joint by applying a hot force to the parts to be joined for a specific time. The applied force serves a dual purpose: it enables contact between the surfaces to be welded and facilitates the elimination of residual porosity in the joints (interfaces) through creep-diffusion. The force can be applied by uniaxial compression, for example, using a press equipped with a furnace or simply by using weights placed on top of the stack of parts to be joined. This process is commonly called uniaxial diffusion welding and is used industrially in the manufacture of plate heat exchangers.

[0023] A significant limitation of the uniaxial diffusion welding process is that it does not allow for welding joints of any orientation relative to the direction of application of the uniaxial compressive force.

[0024] Another alternative process overcomes this drawback. In this process, the force is applied via a pressurized gas within a sealed chamber. This process is commonly called Hot Isostatic Compression (HIC). Another advantage of the HIC diffusion welding process compared to uniaxial diffusion welding is its wider industrial application. Indeed, HIC is also used for batch processing of castings and for powder compaction.

[0025] Other manufacturing processes can also be considered for the production of heat exchangers, such as additive manufacturing, or even a combination of several processes such as the assembly, using one of the aforementioned techniques, of elements produced by additive manufacturing.

[0026] The realization of heat exchangers comprising compact plate exchanger modules arranged in a pressurized shell has already been described in the literature.

[0027] In the nuclear field, and more particularly in the field of liquid metal heat exchangers, present for example in fourth generation nuclear reactors, there are problems of exchanger compactness and high unit thermal power.

[0028] Furthermore, it is necessary to find a heat exchanger between a liquid metal, such as liquid sodium, and a gas, with the requirement of being able to perform a gravity drain of the liquid metal circuit and thus eliminate retention zones within this circuit. Within the framework of the aforementioned application for a prototype liquid sodium-cooled fast neutron nuclear reactor, he has already proposed in patent EP3039373B1 a design solution for a heat exchanger between liquid sodium and a gas that implements compact plate heat exchanger modules within a sealed enclosure.

[0029] We represented at figures 1 to 3, a compact plate heat exchanger module 1 which was envisaged as part of a heat exchange application between liquid sodium, from the secondary loop and nitrogen as a gas under a pressure that can be on the order of 180 bar from the tertiary loop of a liquid metal cooled fast neutron reactor, such as liquid sodium, known as SFR-Na or SFR (English acronym for "Sodium Fast Reactor"), or generally known as LMBFR (English acronym for "Liquid Metal Breeder Fast Reactor").

[0030] This heat exchanger module 1 therefore has two fluid circuits, which is implemented as an example for an exchange between liquid sodium (Na) and nitrogen (N2).

[0031] Such a module 1 consists of an alternating stack of metal plates 10, 20 assembled together by diffusion welding preferably according to a CIC technique.

[0032] Module 1 incorporates two collectors 11 and 12, respectively for the inlet and outlet of liquid sodium (Na). In the configuration of figures 2 And 3 Module 1 extends along a central axis (X), and the input collector 11 is arranged on top of the module along the X-axis, while the output collector 12 is also arranged along the X-axis of the module, but on the underside. In the configuration of the figure 1 , collectors 11, 12 are offset from the central axis (X).

[0033] Each of the collectors 11, 12 opens onto a lateral base of the plate stack onto which the channels of the Na circuit open but not those of the N2 circuit.

[0034] Module 1 also includes two nitrogen (N2) inlet and outlet manifolds, 21 and 22, respectively. In the configuration of figures 2 And 3These collectors 21 and 22 are arranged on the same longitudinal face, respectively at the bottom and top of the module. As detailed later, each of the input collectors 21 and output collectors 22 passes through the stack transversely to the (X) axis and opens onto the channels of the N2 circuit but not onto those of the Na circuit. In the configuration of the figure 1 , the collectors 21, 22 are also offset from the central axis (X).

[0035] In such a module 1, the circulation of fluids (Na, N2) is preferentially counter-current.

[0036] Each metal plate 10, 20 is pre-grooved with grooves 13, 23 which will delimit the channels 14 in which the liquid sodium is intended to circulate and the channels 24 in which the nitrogen is intended to circulate. Circulation within these channels 14, 24 takes place from one or the other of a connection 11, 21 of the inlet manifold C1, C2 to the heat exchange zone ZE via a pre-manifold PC1, PC2 and then by discharge through one or the other of the outlet manifolds 12, 22.

[0037] The pre-collector PC1, PC2 allows the flow distribution in the exchange channels 14, 24 to be corrected as needed by balancing the pressures.

[0038] The inventors of the present invention faced the challenge of optimizing the footprint of compact heat exchangers within the cylindrical main containment of an integrated SMR-type reactor, in order to minimize the reactor size for reasons of investment cost and competitiveness. They analyzed that optimizing the footprint involves reducing the number and dimensions of the heat exchanger components, thereby achieving the smallest possible diameter for the main containment of the integrated reactor and optimizing the connecting piping (quantity and number of penetrations through the vessel).

[0039] More specifically, the specifications for an exchanger that the inventors faced can be summarized in substance as follows: The heat exchangers must be adapted to the dimensional constraints, generally those of the pressure vessel in which they are intended to be installed. In this application for a thermally powered SMR reactor, the modules of a heat exchanger must be arranged in a cylindrical ring delimited by two concentric tanks whose dimensions are dictated by the stack leading to the reactor core and the primary containment. Such a heat exchanger must also meet power requirements compatible with the flow rates and pressures in the circuits; ensure mechanical strength under pressure and temperature in both steady-state and transient operating conditions; guarantee a homogeneous flow distribution between the heat exchange channels while controlling the added pressure drop; and exhibit low thermal inertia to limit the magnitude of thermal stresses during rapid transient regimes.

[0040] Compact heat exchanger modules such as those presented in reference to figures 1 to 3 Their rectangular shape in their usable part facilitates their dimensioning and manufacturing. However, in the case of integration into a sealed cylindrical enclosure that must be dimensioned for pressure, as in the case of an integrated SMR-type reactor, this geometry is not the most optimal.

[0041] There is therefore a need to further improve heat exchanger modules with at least two fluid circuits, in particular to optimize their geometry and better meet the aforementioned specifications.

[0042] The aim of the invention is to at least partially meet this need. Description of the invention

[0043] To this end, the invention relates to a method for making a heat exchanger module with at least two fluid circuits, each comprising channels, comprising the following steps:a / production of one or more elements of one of the two fluid circuits, referred to as the first circuit, and production of one or more elements of at least one other fluid circuit, referred to as the second circuit, each element of the first circuit comprising at least one metal plate having first grooves forming at least a part of the channels of the first circuit, each element of the second circuit comprising at least one metal plate having second grooves forming at least a part of the channels of the second circuit; b / production of one or more sheets each integrating at least a part of the channels of the first circuit and / or the second circuit, either by assembling elements of one and / or the other of the two fluid circuits produced according to step a / and stacked one on top of the other, or by a technique other than assembly;c / Initial bending of the metal plates of the elements of the first and second circuits without their grooves and / or during the creation of their grooves and / or once their grooves have been created, and / or of the layer(s) created according to step b / where applicable stacked together; d / Stacking of the layers, each incorporating at least a portion of the channels of the first circuit and / or the second circuit and initially bent; the stack incorporating, where applicable, solid metal plates, curved or not; e / Placement of the stack from step d / within an assembly tool which also forms a bending gauge, intended to perform a final bend; f / Assembly by hot pressing of the stack within the tooling according to step e / so as to obtain the final assembly with final bend of the heat exchanger module.

[0044] According to an advantageous embodiment, the technique other than assembly according to step b / is an additive manufacturing technique, preferably chosen from metal powder bed fusion by means of a laser or molten metal wire deposition.

[0045] Advantageously, step b / and / or step f / of assembly is carried out either by diffusion welding, or by brazing, or by diffusion brazing.

[0046] According to an advantageous embodiment, the assembly step f / is carried out by applying a high-pressure hot isostatic compression (HIC) cycle to the sheets and / or stack, with the channels of both the first circuit and the second circuit open to the outside.

[0047] According to this method, the CIC cycle according to step f / is preferably carried out at a temperature between 850°C and 1200°C, preferably between 1050°C and 1150°C, a pressure between 500 and 1500 bar with a temperature rise of a duration between 1h and 4h and a temperature maintenance of a duration of 1h to 6h.

[0048] Following this method, prior to step f / of CIC, step e / is carried out with the addition of at least one solid metal plate on either side of the stack to form a pre-module, the insertion of the pre-module into a tool with two blocks of complementary concave and convex shape whose radius of curvature corresponds to that of the final bending, the insertion of the pre-module taken between the two tool blocks into a parallelepiped-shaped container made of folded and welded sheet metal, then a step of vacuuming the inside of the container.

[0049] According to another advantageous embodiment, the process includes a step g / of welding fluid collector tubes onto the module assembled according to step f / , a fluid collector being able to distribute or recover a fluid circulating in the first or second circuit.

[0050] The invention also relates to a heat exchanger module with at least two fluid circuits, in particular obtained according to the process as described above, of a generally curved shape with at least one radius of curvature longitudinal and / or transverse to the fluid circuits.

[0051] According to an advantageous embodiment, the inlet and outlet manifolds are arranged along the longitudinal axis of the module.

[0052] It also relates to a heat exchanger, comprising a plurality of heat exchanger modules as described previously, arranged along a curved surface of the same radius of curvature as that of the modules, the modules being fluidly connected to each other or not.

[0053] The exchanger comprises a generally cylindrical tank, to which the exchanger modules are fixed by being distributed radially, with their internal or external radii of curvature following the internal or external radius of the tank.

[0054] Advantageously, the internal or external radii of curvature of the heat exchanger modules are between 0.5 and 2 times, preferably between 0.75 and 1.25 times, the internal radius of the tank. In an advantageous embodiment, the heat exchanger modules are fixed inside the tank with the inlet and outlet manifolds of their second circuit passing through the tank, for example, radially, or not.

[0055] The invention also relates to the use of the heat exchanger as described above, the fluid of the first circuit, as the primary fluid, being liquid water and the fluid of the second circuit, as the secondary fluid, being liquid water.

[0056] In one preferred application, the fluid in the first or second circuit comes from a nuclear reactor.

[0057] The invention relates to a light water reactor (LWR), of the SMR type, comprising an inner vessel defining a passage to the reactor core and a heat exchanger as described above. A sealed containment is delimited by the inner vessel and the outer vessel to which the heat exchanger modules are attached. The inner and outer vessels are arranged concentrically, forming a cylindrical ring. This containment, designed to operate under pressure, prevents any risk of the modules opening in the event of an incident and can constitute an additional containment barrier. Furthermore, the containment can also act as a collector for one of the two fluids, eliminating the need for separate collectors for that fluid on each module and thus reducing design constraints. Finally, their overall cylindrical shape provides good pressure resistance.

[0058] Advantageously, the internal radius of curvature of the heat exchanger modules matches the internal tank.

[0059] Thus, the invention is essentially a method for manufacturing a heat exchanger module with at least two fluid circuits, designed to give it a final curved shape with at least one radius of curvature longitudinal and / or transverse to the fluid flow. To manufacture the curved heat exchanger modules according to the invention, components to be assembled are first provided.

[0060] These elements can be: either metal plates / sheets on which the channels are obtained by chemical etching or milling on one or both main faces, or by cutting and joining with a solid sheet, these sheets being bent before or after etching; or metal plates / sheets on which the channels are obtained by shaping using techniques such as, for example, stamping, bending, hydroforming, explosion forming, etc., bent before, during or after forming; or fluid sheets assembled, for example, by diffusion welding, from such plates / sheets, and possibly bent or calibrated after assembly; or elements containing channels, such as pieces of sheet, whole sheets or sets of sheets obtained by a direct manufacturing technique such as, for example, laser powder bed fusion or fused wire deposition, these elements advantageously being already curved.

[0061] These elements are then completed by solid metal plates or other elements without channels, curved or not, necessary to reconstitute a module or a rough draft of a module by stacking elements and which will in particular allow to ultimately constitute the edges of the assembly.

[0062] Bending can be carried out using rollers or by a technique allowing the plates or elements to be shaped on a suitable tool (stamping, hydroforming, Guérin process as described under the link: https: / / fr.wikipedia.org / wiki / Proc%C3%A9d%C3%A9_Gu%C3%A9rin), or by free bending, a process in which the deformation takes place using a simple punch with the object to be bent placed on point supports.

[0063] Bending is carried out before the module is assembled because it is not possible on the stack of plates due to the risks of irregular or excessive deformation of the channels, in particular those of the first and last layers.

[0064] The elements are then stacked and assembled by hot pressing, for example by diffusion welding or diffusion brazing.

[0065] However, the assembly operation includes calibrating the stack to give it the desired curvature.

[0066] Indeed, while the initial bending of the components allows for an approximation of the desired curvature, it remains insufficiently precise. The calibration, that is, the final bending, requires specialized tools designed to ensure that the curvature of the assembled module corresponds to the desired value and is maintained throughout the welding process.

[0067] This is the case, for example, in uniaxial diffusion welding, where the compression piles can have a suitable curvature. Similarly, in CIC diffusion welding, the stack can be sandwiched between tools with curved faces in contact with the stack. All or part of the tooling can act as the container. The tooling can be treated to facilitate its disposal; for example, it can be coated with a layer of anti-diffusion material such as alumina.

[0068] After assembly and finishing (machining, removal of the container), the curved modules can be integrated into the annular space of a cylindrical ring forming a pressurized enclosure.

[0069] Other advantages and features of the invention will become clearer upon reading the detailed description of examples of implementation of the invention given by way of illustration and not limitation with reference to the following figures. Brief description of the drawings

[0070] [ Fig 1 ] is a perspective and partial cutaway view of a state-of-the-art heat exchanger module, manufactured by stacking and diffusion-welding metal plates. Fig 2 ] there figure 2 is a front view of a state-of-the-art heat exchanger module, similar to that of the figure 1 . [ Fig 3 ] there figure 3 a longitudinal side view of the heat exchanger module according to the figure 2 . [ Fig 4], [Fig 4A ] THE Figures 4 and 4A These are perspective and top views, respectively, of a state-of-the-art heat exchanger module, based on a first sizing configuration. [Fig. 5], [Fig. 5A ] THE Figures 5 and 5Aare respectively side and top views of a heat exchanger with cylindrical tanks defining a cylindrical ring inside which a plurality of modules are arranged, distributed regularly radially according to the first sizing configuration of the Figures 4 and 4A . [ Fig 6], [Fig 6A ] THE Figures 6 and 6A These are perspective and top views, respectively, of a state-of-the-art heat exchanger module, according to a second sizing configuration. [Fig. 7], [Fig. 7A ] THE Figures 7 and 7A are respectively side and top views of a heat exchanger with cylindrical tanks defining a cylindrical ring inside which a plurality of modules are arranged, distributed regularly radially, according to the second dimensioning configuration of the Figures 6 and 6A . [ [Fig 8], [Fig 8A ] THE Figures 8 and 8Aare perspective and top views, respectively, of a curved heat exchanger module according to the invention, in a third dimensioning configuration. Fig 9], [Fig 9A ] THE Figures 9 and 9A are respectively side and top views of a heat exchanger with cylindrical tanks defining a cylindrical ring inside which a plurality of modules are arranged, distributed regularly radially, according to the third dimensioning configuration of the Figures 8 and 8A . [ [Fig 10], [Fig 10A ] THE Figures 10 and 10A are perspective and top views, respectively, of a curved heat exchanger module according to the invention, in one variant configuration. Fig 11 ] there figure 11is a perspective view of a heat exchanger with cylindrical tanks defining a cylindrical ring inside which a plurality of modules are arranged, distributed regularly radially according to the variant configuration of Figures 10 and 10A . [ Fig 12 ] there figure 12 is a longitudinal cross-sectional view of a curved heat exchanger module implemented in the configuration of Figures 10 and 10A . Detailed description

[0071] For the sake of clarity, the same references designating the same elements of a heat exchanger module according to the prior art and of a heat exchanger module according to the invention are used for all the figures 1 to 12 .

[0072] It is specified that the different elements according to the invention are represented only for the sake of clarity and that they are not necessarily to scale.

[0073] THE figures 1 to 3These points have already been discussed in the introduction. They will therefore not be detailed below.

[0074] To optimize the number of heat exchanger modules, the space required in an integrated reactor, and the piping (number of connecting pipes and penetrations through the sealed enclosure), the inventors propose manufacturing heat exchanger modules 1 with a curved shape. The radius(s) of curvature of such modules can be longitudinal and / or transverse to the fluid flow.

[0075] In the illustrated examples, the radius of curvature is longitudinal and identical to that of the chimney, through which the passage to the core of a pressurized water reactor of the SMR type is found. The two fluid circuits of a heat exchanger module are supplied with pressurized liquid water, typically around 100°C and with pressures on the order of tens of bar.

[0076] To illustrate the advantages of a curved heat exchanger module according to the invention compared to heat exchanger modules of a generally rectangular shape, three configurations of heat exchangers with multiple modules are presented below. These three configurations meet the same specifications for a thermal SMR reactor, i.e., the same total power, total flow rates, temperatures, etc.

[0077] Configuration No. 1 (State of the art): This configuration is illustrated in the following: Figures 5 and 5A : it consists of dimensioning the exchanger 100 from nine identical exchanger modules 1.1 to 1.9 arranged regularly radially in a cylindrical ring of a sealed enclosure delimited by an external tank 3 of internal diameter D1ext and an internal tank 4 of internal diameter D1int.

[0078] In this configuration No. 1, for each module 1.1 to 1.9, the inlet manifolds 11 and outlet 12 of one of the fluid circuits are straight along the longitudinal axis of the tanks 3, 4, while the inlet manifolds 21 and outlet 22 open transversely to the longitudinal axis (X) of the module and pass through the wall of the external tank 4.

[0079] Each of the nine heat exchanger modules 1.1 to 1.9 has a right parallelepiped shape, with dimensions equal to H1*L1*e1, as illustrated in Figures 4 and 4A .

[0080] This configuration No. 1 allows the annular space to be properly distributed between the internal tank 4 and external tank 3, but it has more components to manufacture, more crossings of the external tank 3 and more connections of the pipes to the collectors 11, 12; 21, 22.

[0081] Configuration No. 2 (State of the art): This configuration is illustrated in the following: Figures 7 and 7A: it consists of dimensioning the exchanger 100 from six identical exchanger modules 1.1 to 1.6 arranged regularly radially in a cylindrical ring of a sealed enclosure delimited by an external tank 3 of internal diameter D2ext and an internal tank 4 of internal diameter D2int.

[0082] In this configuration No. 2, for each module 1.1 to 1.6, the inlet manifolds 11 and outlet 12 of one of the fluid circuits are straight along the longitudinal axis of the tanks 3, 4, while the inlet manifolds 21 and outlet 22 open transversely to the longitudinal axis (X) of the module and pass through the wall of the external tank 4.

[0083] Each of the six exchanger modules 1.1 to 1.6 has a right parallelepiped shape, with dimensions equal to H2*L2*e2, as illustrated in Figures 6 and 6A .

[0084] This configuration No. 2 results in fewer components to manufacture, fewer tank penetrations, and fewer connecting pipes than configuration 1, but it leads to an increase in the diameter of the external tank 3. This is due to modules 1.1 to 1.6, which must each transmit more power than in configuration 1 and therefore have a greater thickness of the metal plate stack 10, 20 that make up each module. Furthermore, it is observed that this configuration 2 is not the most optimal in terms of annular space within the cylindrical ring 3, 4.

[0085] Configuration No. 3 (Invention): This configuration is illustrated in the following: Figures 9 and 9A: it consists of dimensioning the exchanger 100 from six identical exchanger modules 1.1 to 1.6 arranged regularly radially in a cylindrical ring of a sealed enclosure delimited by an external tank 3 of internal diameter D3ext and an internal tank 4 of internal diameter D3int.

[0086] In this configuration No. 3, for each module 1.1 to 1.6, the inlet manifolds 11 and outlet 12 of one of the fluid circuits are straight along the longitudinal axis of tanks 3, 4, while the inlet manifolds 21 and outlet 22 open transversely to the longitudinal axis (X) of the module and pass through the wall of the external tank 4.

[0087] Each of the six heat exchanger modules 1.1 to 1.6 has a generally curved shape in the transverse direction, i.e., with a radius of curvature in the direction perpendicular to the fluid flow within each module, of dimensions equal to H3*L3*e3, as illustrated in Figures 8 and 8A .

[0088] This configuration No. 3 allows us to have both the advantages of configuration No. 1 (smaller diameter of tanks 3, 4, optimization of the annular space) and those of configuration No. 2 (fewer components to manufacture, fewer tank crossings and connecting piping).

[0089] We can therefore see that by adapting here the width of the metal plates 10, 20 which constitute each module, from a flat geometry to a curved geometry of the exchanger modules, we optimize the exchanger 100 in the cylindrical ring 3, 4 around an integrated SMR type reactor.

[0090] Table 1 below gives, for guidance purposes, the numerical values ​​of the dimensions of the exchanger modules and exchangers in the different configurations presented above. [Table 1] Configuration No. 1 (State of the art) No. 2 (State of the art) No. 3 (Invention) Dimensions (m) Heat exchanger module 1.1 to 1.9 H1 = 2,55 H2 = 2,55 H3 = 2,55 L1 = 0,5 L2= 0,5 L3 = 0,75 e1 = 0,28 e2 = 0,43 e3 = 0,28 Internal tank 4 D1int = 1.7 D2int = 1.7 D3int = 1.7 External tank 3 D1ext = 2.4 D2ext = 2.7 D3ext = 2.4

[0091] The internal radius of curvature of a 1.1 to 1.9 exchanger module is approximately 1 m.

[0092] We now describe an example of a method for making a curved exchanger module according to the invention.

[0093] Step a: First, elements of a first and second fluid circuit are made, each from metal plates 10 or 20 of rectangular shape and thickness e, identical to each other, grooves 13 or 23 of depth p, width 11 and given spacing s.

[0094] Two plates, 10 or 20, are machined according to two patterns that are mirror images of each other.

[0095] Patterns can be created with studs in a part in continuity with the grooves, intended to form a pre-collector PC1, PC2, as described in the patent application filed in France on May 6, 2021 under number FR2104813.

[0096] As an example, the plates are made of 1.4404 stainless steel, the dimensions L*1*h of a plate I are equal to 1600*400*4 mm, the dimensions p* 11 of the grooves are equal to 1.5*3 mm with tolerances respectively equal to ± 0.02 mm and ±0.05 mm, the distance s between two consecutive grooves, i.e. the width of an isthmus, is equal to 1 mm with a tolerance equal to ±0.05 mm.

[0097] Step al / : we carry out a cleaning using solvents and detergents of plates 10 or 20.

[0098] Step a2: After cleaning them, the two plates 10 or 20 are stacked to recreate an element of the first or second fluid circuit, comprising a series of channels 14 or 24 with a cross-section of 3 x 3 mm in this example. The two plates are aligned with each other using centering pins (not shown).

[0099] Step b / : we create several layers, each incorporating at least part of the channels of the first circuit and / or the second circuit, by assembling the elements of the two fluid circuits created.

[0100] Step bl / : the periphery of each element consisting of the two metal plates 10 or 20 stacked one on top of the other forming the channels 14 or 24 is sealed by welding. Thus, a weld bead is made around the periphery of each pair of plates 10 or 20 so as to seal the space / interface between them.

[0101] Step b2: The interface between the two plates of each sealing element is degassed through a through-hole. To do this, the space is evacuated by pumping via a nozzle welded to one of the two plates 10 or 20 opposite a hole opening into this space.

[0102] Step b3: The opening is closed. To do this, the tube forming the tail is sealed airtight by crushing and welding.

[0103] Step b4: A batch of several identical elements is subjected to a low-pressure CIC cycle, comprising heating for 2 hours to 1020°C under 60 bar, a one-hour holding period at 1020°C under 60 bar, then cooling over several hours, and finally depressurization. Flat sheets measuring 400 x 1600 x 6 mm are then obtained.

[0104] Step b5 / : The sheets are then milled to remove 1.75 mm of thickness from each of their main faces to bring their thickness back to 4.5 mm.

[0105] Step c:An initial bending is then performed on each of the sheets produced according to step b / . This initial bending takes place on a roller across the width of the sheets, that is, perpendicular to the direction of fluid flow. In this example, the bending radius is 660 mm, to obtain a deflection of approximately 30 mm with the dimensions indicated above.

[0106] Step cl / : the curved tablecloths are cleaned using solvents and detergents.

[0107] Step d: We then carry out a head-to-tail stacking of these curved sheets according to step c / .

[0108] Stage e / : The stack from step d / is then placed within an assembly tool which also forms a bending gauge, intended to perform a final bending.

[0109] Step e1 / : prior to the final bending itself, a solid metal plate with a thickness of 15 mm, already bent to a radius of curvature of 660 mm, is added on either side of the stack.

[0110] Step e2: The stack, with the two solid, curved plates on either side, is placed between two steel tooling blocks. One block has one flat face and one concave face, and the other has one flat face and one convex face complementary to the concave face of the first block. The radius of curvature of the complementary convex / concave faces is 660 mm.

[0111] The resulting assembly then has a parallelepiped external shape defined by the longitudinal edges of the sheets and solid plates and by the flat faces of the two tool blocks.

[0112] Step e3 / : The assembly is inserted into a parallelepiped-shaped container made of folded and welded sheet metal.

[0113] Step e41: We perform welding and degassing of the container.

[0114] Stage f / The assembly process involves applying a CIC cycle, stacking the components within the tooling according to step e / to obtain the final assembly with final bending of the heat exchanger module. This CIC cycle, known as high-pressure heating, includes heating at 1080°C under 1000 bar for 3 hours.

[0115] During this high-pressure CIC cycle, the sheets weld together by diffusion.

[0116] The container and tooling blocks are disposed of. Preferably, the tooling is demolded for disposal. Disposal by machining can also be considered.

[0117] Stage g / : fluid collectors 11, 12 or 21, 22 are welded opposite the outlets of channels 14 or 24.

[0118] This results in a curved heat exchanger module 1, ready to be inserted and fixed in an enclosure such as that delimited by tanks 3 and 4. figures 9 and 9A .

[0119] Other variations and improvements can be made without going outside the scope of the invention.

[0120] For example, one can consider curved heat exchanger modules with one of the fluid circuits in a general U-shape, one branch of which allows counter-current circulation with the fluid from the other circuit, and the other branch is co-current, as shown in the diagrams. figures 10, 10A And 12 for a module 1 with input collectors 21 and output collectors 22 of one of the two circuits on either side of the input collector 11 of the other of the two circuits.

[0121] In addition, patterns can be made with studs in a part, in continuity with the collectors 21, 22, intended to form a pre-collector PC1, PC2, as described in the patent application filed in France on May 6, 2021 under No. FR2104813.

[0122] As an example, the dimensions of module 1 on these figures 10 and 10A are as follows: H4 = 2.55m, L4 = 1.25m and e4 = 0.29m.

[0123] As shown in the figure 11 , we can arrange such modules in a space between two cylindrical tanks 3, 4 with no collector 11, 12, 21, 22 that cross either of these tanks 3, 4 since they extend in this space along the longitudinal axis of the modules, parallel to the axis of the tanks.

Claims

1. Method for producing a heat exchanger module (3) having at least two fluid circuits each having channels, involving the following steps: a / production of one or more elements (1.1) of one of the two fluid circuits, referred to as the first circuit, and producing one or more elements of at least one other fluid circuit, referred to as the second circuit, each element of the first circuit having at least one metal plate (1) having first grooves forming at least a portion of the channels (4) of the first circuit, each element of the second circuit having at least one metal plate (1) having second grooves (20) forming at least a portion of the channels (5) of the second circuit; b / production of one or more layers each incorporating at least a portion of the channels of the first circuit and / or of the second circuit, either by assembly of elements of one and / or the other of the two fluid circuits produced according to step a / and stacked on one another, or by a technique other than assembly; c / initial bending of the metal plates of the elements (10, 20) of the first and second circuits without their grooves and / or during the production of their grooves and / or once their grooves have been produced, and / or of the layer(s) produced according to step b / if appropriate stacked together; d / stacking of the layers each incorporating at least a portion of the channels of the first circuit and / or of the second circuit and initially bent; the stack incorporating, if appropriate, solid metal plates, which may or may not be curved; e / putting in place of the stack of step d / within an assembly tool also forming a curve gauge, intended to carry out a final bending; f / assembly by hot pressing of the stack within the tool according to step e / so as to obtain the definitive assembly with final bending of the heat exchanger module.

2. Method according to Claim 1, the technique other than assembly according to step b / being an additive manufacturing technique, preferably selected from metal powder bed fusion by means of a laser or molten metal wire deposition.

3. Method according to Claim 1 or 2, step b / and / or step f / of assembly being carried out by diffusion welding, by brazing or by diffusion brazing.

4. Method according to Claim 3, step f / of assembly being carried out by applying a high pressure hot isostatic pressing (HIP) cycle to the layers and / or to the stack, the channels of both the first circuit and the second circuit being open to the outside.

5. Method according to Claim 4, the HIP cycle according to step f / being carried out at a temperature of between 850°C and 1200°C, preferably between 1050°C and 1150°C, a pressure of between 500 and 1500 bar with a rise in temperature for a time of between 1h and 4h and holding of the temperature for a time of 1h to 6h.

6. Method according to either of Claims 4 and 5, wherein there is performed, before step f / of HIP, step e / comprising: e1 / adding at least one solid metal plate on either side of the stack to form a pre-module, e2 / inserting the pre-module into a tool having two complementary blocks of concave and convex shape of which the radius of curvature corresponds to that of the final bending, e3 / inserting the pre-module held between the two tool blocks into a container of parallelepipedal shape made of folded and welded sheet metal, then e4 / a step of placing the inside of the container under vacuum.

7. Method according to one of the preceding claims, comprising a step g / of welding fluid manifold tubes (11, 12; 21, 22) to the module assembled according to step f / , a fluid manifold being able to distribute or recover a fluid circulating in the first or second circuit.

8. Heat exchanger module (1; 1.1 to 1.6) having at least two fluid circuits, obtained according to the method according to any one of the preceding claims, of curved overall shape with at least one radius of curvature that is longitudinal and / or transverse with respect to the circuits of the fluids.

9. Heat exchanger module (1; 1.1 to 1.6) having at least two fluid circuits, according to Claim 8, the inlet (11, 21) and outlet (12, 22) manifolds being arranged along the longitudinal axis of the module.

10. Heat exchanger, comprising a plurality of heat exchanger modules (1.1 to 1.6) according to Claim 8 or 9, arranged along a curved surface of the same radius of curvature as that of the modules, the modules being or not being fluidically connected to each other.

11. Heat exchanger according to Claim 10, comprising a vessel of cylindrical overall shape, to which the exchanger modules are fastened, being distributed radially, preferably regularly, with their internal or external radii of curvature matching the internal or external radius of the vessel.

12. Heat exchanger according to Claim 11, the internal or external radii of curvature of the exchanger modules being between 0.5 and 2 times, preferably between 0.75 and 1.25 times, the internal radius of the vessel.

13. Heat exchanger according to Claim 12, the exchanger modules being fastened inside the vessel with the inlet (11, 21) and outlet (12, 22) manifolds of their second circuit passing through, in particular radially, the vessel, or not.

14. Use of the heat exchanger according to Claim 12 or 13, the fluid of the first circuit, as primary fluid, being liquid water and the fluid of the second circuit, as secondary fluid, being liquid water.

15. Use according to Claim 14, the fluid of the first or second circuit originating from a nuclear reactor.

16. Light water nuclear reactor (LWR), of SMR type comprising an internal vessel defining a passage to the core of the reactor and a heat exchanger according to Claim 13, a sealed enclosure being delimited by the internal vessel and the vessel to which are fastened the exchanger modules forming the external vessel, the internal and external vessels being arranged concentrically forming a cylindrical ring.

17. Nuclear reactor (PWR) according to Claim 16, wherein the internal radius of curvature of the exchanger modules matches the internal vessel.