High shear and low drag centripetal mixer

Abstract

The present invention relates to a high-shear centripetal fluid mixer (1). The mixer (1) comprises a shaft (2) configured to rotate about an axis (X), two supports (3a, 3b) mounted on the shaft (2), and a set of blades (4a, 4b) mounted on the supports (3a, 3b). The path described by the movement of the blades (4a, 4b) forms a surface of revolution whose axis of revolution corresponds to the axis (X), the supports (3a, 3b) forming the longitudinal ends of the surface of revolution, and the set of blades (4a, 4b) forming the lateral face of the surface of revolution. Each of the blades (4a, 4b) extends at a substantially inclined angle to a tangent of the lateral face, so as to impart a force to the fluid directed towards the axis (X) of the shaft (2). Figure for the summary: Figure 1

Description

Title of the invention: High shear and low drag centripetal mixer technical field

[0001] The present invention relates to the field of mixers, also called “agitators”.

[0002] The present invention relates more particularly to a centripetal mixer configured to generate significant shear of the mixed fluid, while requiring reduced driving power.

[0003] The present invention will thus find many advantageous applications in all fields requiring the mixing of products.

[0004] The present invention will find particularly advantageous applications in the manufacture of precursors of active cathode materials. Previous art

[0005] Mixers, or "agitators", are used for all kinds of applications such as product mixing, emulsification, homogenization, disintegration, solubilization, suspension, agglomerate dispersion and solid grinding, or even the control of a chemical reaction.

[0006] They are used in particular in the chemical industry, papermaking, hydrometallurgy, cosmetics, pharmaceutical, food processing, paint and coatings, plastics, and nuclear industries.

[0007] In many cases, a high shear effect is desired in the mixed fluid in order to cause, as appropriate, the intimate mixing of fluids of very different viscosities, a decrease in the viscosity of thixotropic fluids, the attrition of suspended particles, the disintegration of particle clusters, etc. High shear is particularly advantageous in mixtures that otherwise require a long stirring time, for example when powders are dispersed and hydrated, when an emulsion or suspension is formed, or when solids are dissolved or disintegrated.

[0008] The implementation of high shear then makes it possible to reduce mixing times, therefore electricity consumption, and to improve the quality and consistency of the product.

[0009] So-called "ship's propeller" agitators are known to generate only low shear. They are therefore used when high shear is undesirable, for example, to protect a fragile product or one with a delicate consistency (e.g., chocolate). Spiral ribbon agitators are very popular and simple to manufacture in metal. However, they also have a poor shear effect.

[0010] Many high-shear agitator designs are based on a propeller principle, with various shaped appendages designed to increase shear. Two examples of turbines that deviate from this principle are the so-called "De Rushton" turbine and the "squirrel cage" agitator.

[0011] The Rushton turbine has rectangular blades oriented perpendicular to their direction of motion. The liquid is drawn into a double torus motion. The interaction between the liquid and the blades, particularly at the blade tips, creates shear in the liquid. Thus, the maximum shear effect of designs based on Rushton turbines tends to occur in the immediate vicinity of the device components, especially the blades, resulting in significant wear. Furthermore, these turbines require considerable motive power and have the drawback of driving the entire liquid into a rotary motion that must be counteracted by fixed counter blades. In the direction of the axis of rotation, the Rushton turbine has a limited reach, sometimes requiring designers to mount several turbines on the same axis.A variant of this type of turbine has slightly inclined blades, to impart a vertical movement to the liquid mass, that is to say a movement along the axis of rotation.

[0012] Squirrel cage agitators have one or more perforated cylinders fitted with a large number of vertical blades. These blades expel the liquid outward from the turbine, like Rushton turbines. The liquid returns through the ends of the cylinder. The operation of the squirrel cage turbine is not very different from that of the Rushton turbine. Inexpensive squirrel cage turbines, made of molded plastic, are sold to consumers for mixing paints. Like Rushton turbines, they tend to impart a rotational motion to the liquid mass, which must be counteracted and requires considerable power.

[0013] The Applicant therefore submits that there is currently no satisfactory alternative mixer solution that generates high fluid shear while minimizing the energy required and wear on mechanical parts. Summary of the invention

[0014] The present invention aims to improve the current situation described above.

[0015] The present invention is more particularly aimed at overcoming the following drawbacks: above by proposing a mixer configured to generate a significant shear effect, without seeking to set the fluid in motion.

[0016] To this end, the object of the present invention relates in a first aspect to a high-shear centripetal mixer for fluid, which comprises a shaft extending along an axis and configured to be driven in rotation around the axis, the mixer further comprising: - two supports assembled on the tree and offset from each other along the tree; and - a set of blades assembled on supports so as to extend substantially parallel to the axis of the shaft, at a distance from the shaft.

[0017] It is understood here that the assembly of the supports on the shaft and of the blades on the supports results in the drives, via the rotation of the shaft around the axis, of the supports and the blades around the axis. Furthermore, by substantially parallel, it is understood that the blades extend primarily along the direction of the shaft axis, for example in a strictly parallel manner, or even with a curvature along the axis.

[0018] Advantageously, the trajectory described by the movement of the blades forms a surface of revolution whose axis of revolution corresponds to the axis of the shaft, the supports forming the longitudinal ends of the surface of revolution and the set of blades forming the lateral face of the surface of revolution.

[0019] In other words, the supports and the blade assembly, through their movement, form the constituent parts of the surface of revolution. The surface of revolution forms a cage for the fluid; that is, it defines an internal space in which the fluid flows to be mixed by the action of the blades. It is understood here that the mixer has a substantially regular shape around the axis of revolution, so as to define the shape of the surface of revolution. The blades are, for example, all assembled at the same distance from the shaft, or they may have similar shapes offset angularly with respect to the shaft axis. For example, the blades can be curved along the shaft axis, so as to approach the shaft at the level of the supports and move away from the shaft at a distance from the supports, the blades all having a similar curvature along the axis.It is also understood that the extension of the blades along the shaft axis helps to guarantee the turbine's reach, in comparison to the limited reach of Rushton turbines.

[0020] Advantageously, the blades each extend in a substantially inclined manner with respect to a tangent of the lateral face, so as to impart to the fluid a force directed towards the axis of the shaft.

[0021] It is understood here that the blades exert a centripetal force on the fluid, that is to say towards the center of the mixer, the mixer being centered on the axis of the shaft.

[0022] By substantially inclined, it is meant here that the blades are substantially parallel to the tangent of the lateral face, and have an inclination at a non-zero angle with respect to this tangent, for example an angle greater than 1° and less than 30°. The blade orientation here differs from blades that are substantially perpendicular to the tangent of the lateral face, particularly those of a Rushton turbine. In other words, the blades according to the present invention are oriented with a slight inclination relative to their direction of motion. Furthermore, it is understood that the inclination is oriented so as to direct the fluid towards the shaft axis, that is, centripetally, as opposed to blades inclined so as to impart motion along the shaft axis, as is known to be the modification of Rushton turbines, or as is also practiced in other mixer designs, particularly ribbon mixers. The blade inclination according to the present invention thus differs from that of mixers known to those skilled in the art.

[0023] It is also understood that the concept of inclination is taken into account with respect to the shape of the lateral face. For example, blades are provided, each extending in a plane substantially inclined with respect to a tangent of the lateral face, particularly as described below in a surface of revolution corresponding to a cylinder of revolution. In the case of curved blades, the blade inclination also takes into account the curved shape of the lateral face. It is also possible that such an inclination may partially impart a force to the fluid directed along the axis, particularly towards a central portion of the shaft with respect to its axis due to the curvature of the blades.

[0024] It is understood here, of course, that the blade pitch is selected in conjunction with the clockwise or counterclockwise rotation of the shaft, so as to generate a centripetal, rather than a centrifugal, force on the fluid. The blades are preferably mounted on the supports so that their pitch is fixed. According to another embodiment, the blades can be designed to be mounted on the supports in such a way as to allow the pitch to be adjusted, for example, within a range of angles corresponding to a low pitch as defined above.

[0025] The Applicant submits that the centripetal force imparted to the fluid creates currents towards the center of the device, which generate turbulence and high fluid shear. In particular, the device according to the present invention combines high centripetal thrust and low drag. The reduction in drag corresponds to minimal driving of the rotating fluid by the blades, as the rotational motion does not generate fluid shear. This design thus reduces unnecessary fluid movement, thereby reducing the driving power and the amount of energy required for fluid shear. Furthermore, since the fluid shear results from the opposing currents at the center of the device, this shear occurs in the middle of the liquid and not at the blade contact points, thereby reducing blade wear.

[0026] Thanks to the present invention, it is therefore possible to perform high-shear mixing at the center of the mixer, minimizing superfluous fluid movement and power consumption, as well as mixer wear. Furthermore, the high shear achieved ensures the quality and consistency of the mixed fluid(s).

[0027] In an embodiment that can be combined with the following embodiments, the supports form two extreme faces of the surface of revolution, each of the supports being associated with one of the extreme faces and substantially inclined with respect to a tangent of the associated extreme face, so as to impart to the fluid a force directed towards a central portion of the shaft.

[0028] It is understood here that, in this design, the supports also have a blade-like function, that is to say, their movement imparts a force on the fluid. The supports, for example, have the same characteristics as the blades as described in the rest of the description, particularly in terms of angle of incidence and / or profile as described below, such characteristics being adapted with respect to the orientation of the supports so as to minimize drag and maximize thrust along the axis.

[0029] The supports thus incorporate the principle of inclined blades designed to impart movement along the shaft axis, as known in the prior art. Two supports function as a pair of opposing blades, directing the fluid towards the center of the mixer, rather than simply moving the fluid along the axis. The supports therefore correspond to "axial" blades in combination with "radial" blades. In other words, a first support is inclined to direct the fluid towards a second support, and conversely, the second support is inclined to direct the fluid towards the first support. For a mixer oriented substantially vertically, a lower support can thus be defined, directing the fluid upwards and an upper support, directing the fluid downwards.

[0030] For example, when the surface of revolution corresponds to a cylinder of revolution, the extreme faces of the surface of revolution extend along two planes perpendicular to the axis of the shaft, the supports also extending perpendicularly to the axis of the shaft and being inclined with respect to the two perpendicular planes.

[0031] The Applicant submits that such a design makes it possible to further increase the fluid shear by generating turbulence with respect to axial movements, in addition to turbulence with respect to radial movements about the same axis. The combined action of the blades and supports directs the fluid towards a central point in the mixer in order to maximize shear at the center of the mixer, away from the blades and supports.

[0032] In an advantageous embodiment of the present invention, the supports extend perpendicularly to the axis of the shaft, the blades extend parallel to the axis of the shaft so that the surface of revolution corresponds to a cylinder of revolution.

[0033] It is understood here that the supports form the lower and upper faces, or extremal faces, of the cylinder of revolution, while the blades form the lateral face as described above. The supports extend, for example, along two planes perpendicular to the axis of the shaft. In particular, the blades have no curvature, and the distance between the blades and the shaft corresponds to the radius of the cylinder of revolution. This design allows for a compact implementation of the mixer and smooth operation along the axis. Those skilled in the art understand that it is possible to design a variety of shapes for the supports and blades, depending on the desired surface area of ​​revolution, the structural constraints to be met by the mixer, or additional effects desired on the mixed fluid.

[0034] In an additional embodiment, the blade assembly comprises at least one pair of blades arranged opposite each other with respect to the axis.

[0035] It is understood here that opposing blades create symmetrical opposing forces, and by extension symmetrical currents, so as to ensure shear at the center of the device. In particular, it is advantageous to provide that the blades of a pair have the same inclination, so as to impart the same forces on the fluid.

[0036] According to other examples, the blades are arranged at regular angular intervals around the axis, for example three blades are arranged at intervals of 120° from each other.

[0037] In an additional embodiment, the supports and the blade assembly form a single unit.

[0038] In other words, all the blades are supported by the same element, which is assembled with the shaft along its longitudinal ends. The one-piece element thus forms a cage that defines the surface of revolution by its rotation.

[0039] In another embodiment, the mixer comprises a first part and a second part both assembled with the shaft, the first part comprising a first of the supports and a first portion of the blade assembly and the second part comprising a second of the supports and a second portion of the blade assembly.

[0040] It is understood here that the first part and the second part form two half-cages, jointly defining the surface of revolution by their rotation. Each half-cage includes a portion of the lateral face and a longitudinal end (e.g. upper or lower) of the surface of revolution.

[0041] Preferably, the first part and the second part have an identical structure, the second part being symmetrical to the first part along a median plane of the surface of revolution and having an angular offset with respect to the first part.

[0042] Here, the median plane is understood to be a plane perpendicular to the axis of the tree, and located equidistant from the two supports.

[0043] It is understood here that this design corresponds to a simplified embodiment in which the two parts have the same shape, facilitating their manufacture. Each part comprises, for example, two lateral blades connected by an upper or lower support. The two parts are angularly offset from each other, that is to say, they are not positioned opposite each other. Advantageously, an angular offset of approximately 90° between the two parts is provided, so as to ensure consistent mixer behavior. The offset between the two parts thus allows them to be nested together, and all the blades act on the fluid along their common length.

[0044] Preferably, the first piece and the second piece are assembled on the shaft so that the first portion and the second portion of the blade assembly overlap along the majority of their length.

[0045] In other words, the two parts are nested, so that the major part of the surface of revolution is composed of the conjunction of the first and second portions of the blade assembly. Over the entire common length, that is to say, here over the majority of the blade length, all the blades have a joint action so as to maximize the efficiency and compactness of the mixer.

[0046] In yet another embodiment, for at least one of the blades, the cross-section along a plane perpendicular to the axis of the shaft defines a curved shape having an angle of incidence corresponding to the inclination of the blade.

[0047] Those skilled in the art will understand that the concept of angle of incidence, also called angle of attack, in the field of fluid mechanics, corresponds to the angle between the blade and the fluid motion, or, in the context of a mixer, to the angle between the blade and its own rotational motion, corresponding, as described above, to a tangent to the lateral face of the surface of revolution. The angle in question is determined, with respect to the cross-section, from the chord of the curved shape, that is, from a straight line between the two ends of the cross-section along its length. In other words, the blade does not have a flat shape, but a curved shape defining a width and a length, the curved shape extending between two longitudinal ends, the chord corresponding to a fictitious straight line between the longitudinal ends and the angle of incidence corresponding to the angle between the chord and the direction of the blade's movement.

[0048] Preferably, for at least one of the blades, the curved shape corresponds to a profile with a leading edge and a trailing edge, the profile defining the angle of incidence.

[0049] It is understood here that the notion of profile in the sense of the present invention is to be taken in the sense of fluid mechanics, or more precisely in the sense of an aerodynamic element, applied to the mixture of fluids, here preferably to the mixture of liquids or solutions. The leading edge corresponds to a first longitudinal extremity of the curved shape and the trailing edge to a second longitudinal extremity of the curved shape, the leading edge corresponding to the "front" and the trailing edge to the "back" with respect to the movement of the blade.

[0050] Preferably, the leading edge having a rounded shape and the trailing edge a tapered or pointed shape. In other words, the curved shape corresponds to the shape of an aircraft wing cross-section. Obviously, this concept includes a plurality of shapes, for example, a biconvex shape in which both faces of the blade are convex, or a concave shape in which one face of the blade is convex and the opposite face is concave. It is further understood here that providing a leading edge and a trailing edge of specific shapes makes it possible to clearly define the expected direction of blade movement, and by extension the orientation of the blades with respect to this direction and the centripetal operation of the mixer.

[0051] Those skilled in the art understand that an aircraft wing profile creates high lift and minimal drag. The lift generated by an aircraft wing translates into an opposing force on the fluid, thus generating a centripetal force in the mixer. Applying such a profile to the curved shape of the blades therefore maximizes the centripetal force and minimizes drag, i.e., maximizes shear and minimizes the energy required.

[0052] In one embodiment, the blades of the third subassembly are inclined at an angle between 2° and 15° with respect to the tangent of the lateral face.

[0053] It is understood here that the angle corresponds to the angle of incidence as described above, when the blade has a curved shape.

[0054] A person skilled in the art understands further that, while variations in angle can affect centripetal thrust, the greater the angle, the greater the drag. The choice of angle thus corresponds to finding a balance between centripetal thrust and drag, for example, depending on the fluids to be mixed, the desired shear level, energy constraints, the material selected, and the desired lifespan of the mixer. The Applicant therefore submits that a range of 2° to 15° makes it possible to obtain an interesting compromise between mixer shear and energy and mechanical constraints. Furthermore, while a higher angle can increase lift as defined above, and a force on the fluid opposing this lift, this opposing force is only partially centripetal, and contributes partially to driving the fluid into rotation rather than generating shear.

[0055] In a preferred embodiment, the blade assembly is dimensioned so that the surface of revolution formed by the movement of the blades has a ratio between its maximum diameter and its height of between 0.5 and 2.

[0056] It is understood here that the maximum diameter of the surface of revolution corresponds to the maximum distance between the blades and the shaft, this distance being able to vary along a blade with a curve, and the height of the surface of revolution corresponds to the distance between the supports. When the surface of revolution corresponds to a cylinder of revolution, the diameter corresponds to the width of the supports and the height corresponds to the distance between the supports.

[0057] In one embodiment, the mixer is made of composite materials and / or polymers.

[0058] It is understood here that the choice of material makes it possible to ensure simple manufacturing, while ensuring superior resistance to corrosion and the absence of pollution of the mixed fluid by metallic ions or particles.

[0059] In yet another embodiment, the mixer is designed for the manufacture of precursors of active cathode materials.

[0060] Precursors of cathode active materials, also called pCAMs (from the English "Precursors of Cathode Active Materials"), are an intermediate product in the manufacture of batteries, particularly automotive batteries. The manufacture of pCAMs involves the use of a mixer, or agitator, which is used in a reactor in which the pCAM grains are formed.

[0061] The Applicant submits in particular that the agitators commonly used in the field consume a lot of energy, and that the formation of pCAM grains requires high shear.

[0062] The mixer according to the present invention, adapted for the manufacture of pCAM, thus makes it possible to provide performance greatly superior to that of the prior art, ensuring a regular and high-quality finished product, while requiring less energy for its manufacture.

[0063] According to a second aspect, the present invention relates to the use of a high shear centripetal mixer according to the first aspect of the present invention for the manufacture of precursors of active cathode materials.

[0064] In other words, the present invention covers a method for manufacturing precursors of active cathode materials, which includes a stirring step using a mixer according to the first aspect of the present invention. The variants described with regard to the first aspect of the present invention are also applicable, mutatis mutandis.

[0065] It is further understood that the use of a centripetal mixer according to the invention includes driving the mixer shaft in a direction configured to ensure the generation of centripetal forces, i.e. a clockwise or counterclockwise direction depending on the orientation of the blades.

[0066] According to a third aspect, the present invention relates to a precursor of active cathode material obtained by the use of a high shear centripetal mixer according to the first aspect of the present invention.

[0067] In other words, the present invention relates to an active material precursor obtained via the use according to the second aspect of the present invention.

[0068] A pCAM can be composed of a mixture of materials known to those skilled in the art, for example a mixture of Nickel, Cobalt and Manganese, for example having a composition such as described in one of the documents EP 3693340 A2 or WO 2020175925 Al. Those skilled in the art understand obviously that the composition of the pCAM depends on the active cathode material sought, which may correspond to a lithium cobalt oxide (LiCoO2), a lithium manganese oxide (LiMn2O4), a lithium iron phosphate (LiFePO4 or LFP) or a lithium nickel manganese cobalt oxide (LiNiMnCoO2 or NMC).

[0069] As stated previously, the manufacture of a pCAM using a mixer according to the invention, via its high shear, makes it possible to increase the quality and regularity of the pCAM obtained.

[0070] According to a fourth aspect, the present invention relates to a cathode active material obtained from a cathode active material precursor according to the third aspect of the present invention.

[0071] According to a fifth aspect, the present invention relates to a battery, preferably a vehicle battery, comprising an active cathode material according to the fourth aspect of the present invention.

[0072] Thus, by the various functional and structural technical characteristics above, the Applicant proposes a mixer configured to generate a strong centripetal high shear on a fluid, which minimizes any superfluous movement of the fluid and creates shear away from the blades, in a less energy-intensive and more robust design. Description of the figures

[0073] Other features and advantages of the present invention will become apparent from the description of the particular and non-limiting embodiments of the present invention below, with reference to the attached Figures 1 to 5, in which:

[0074] [Fig.1]

[0075] Fig. 1 schematically illustrates a first perspective view of a mixer according to an example of an embodiment of the present invention;

[0076] [Fig.2]

[0077] [Fig.2] schematically illustrates a second perspective view of a mixer conforming to [Fig.1];

[0078] [Fig.3]

[0079] Fig. 3 schematically illustrates a third perspective view of a mixer conforming to Fig. 1;

[0080] [Fig.4]

[0081] [Fig.4] schematically illustrates a fourth perspective view of a mixer conforming to [Fig.1];

[0082] [Fig.5]

[0083] Fig. 5 illustrates a cross-sectional view along a plane perpendicular to the axis of the shaft of a mixer conforming to Fig. 1. Detailed description

[0084] A high shear mixer will now be described in what follows with joint reference to Figures 1 to 5. The same elements are identified with the same reference signs throughout the description that follows.

[0085] As indicated in the preamble to the description, high-shear mixers of the prior art tend to impart a rotational motion to the entire liquid, which consumes significant energy and necessitates a more complex mixer structure through the addition of counter blades. In particular, mixers used in the manufacture of precursors for active cathode materials are especially energy-intensive.

[0086] One of the objectives of the present invention is to provide a centripetal mixer capable of producing high shear in a fluid, in particular in a liquid, while limiting the associated energy requirements.

[0087] This is made possible in the example described below.

[0088] As illustrated in Figures 1 to 5, the example described here includes a mixer 1 configured for mixing fluids, in particular liquids. The mixer 1 is preferably designed for the fabrication of precursors of cathode active materials (or pCAMs), for example, for use in a reactor in which pCAM grains are formed. The mixer 1 is for example, specifically designed for the production of a precise composition, for example, a precursor of an active material composed of LiCoO2, LiMn2O4, LiFePO4, or LiNiMnCoO2. The mixer 1 is thus, for example, made of composite materials and / or polymers, specifically selected for their neutrality with respect to the particles and / or ions contained in the fluids to be mixed.

[0089] According to the example in Figures 1 to 4, the mixer 1 comprises a shaft 2 extending along an axis X. The shaft 2 is, for example, configured to be connected to a drive system or any other means of driving the shaft 2 around the axis X. The mixer 1 further comprises two supports 3a, 3b, assembled at two points on the shaft 2, along the axis X, and a set of blades 4a, 4b, assembled on the supports 3a, 3b. The blades 4a, 4b extend along the shaft 2, in a manner substantially parallel to the X axis.

[0090] In this same example, the supports 3a, 3b extend perpendicularly to the X-axis, the blades 4a, 4b being fixed to the ends of the supports 3a, 3b, and extending parallel to the X-axis. The blades 4a, 4b are also arranged in pairs, so that each blade 4a, 4b is associated with another blade 4a, 4b, symmetrical with respect to the X-axis. In particular, this design allows for the arrangement of two flat supports 3a, 3b extending perpendicularly to the X-axis longitudinally, the blades 4a, 4b being assembled at the longitudinal ends of the supports 3a, 3b.

[0091] It is understood that in other examples, the supports 3a, 3b and the blades 4a, 4b can take other forms. According to one particular example, the supports 3a, 3b correspond to two attachment elements for the blades 4a, 4b, which extend along a curvilinear path along the X-axis, so as to move away from the shaft 2 at a distance from the supports 3a, 3b. The blades 4a, 4b can also be arranged at other intervals around the X-axis, for example at regular angular intervals, or even at irregular intervals, if such a choice provides a particular advantage in the mixing of the fluid.

[0092] As illustrated in Figures 1 to 4, the supports 3a, 3b and the blades 4a, 4b are grouped into a first part 5a and a second part 5b, each part 5a, 5b forming a single unit, i.e., the blades 4a, 4b form a single unit with the supports 3a, 3b to which they are attached. Thus, the first part 5a comprises a first support 3a and a first portion 4a of the blade assembly 4a, 4b, and the second part comprises a second support 3b and a second portion 4b of the blade assembly 4a, 4b. In a simple design, the first part 5a and the second part 5b have an identical design, the second part 5b being symmetrical to the first part 5a with respect to a median plane between the two supports 4a, 4b. In other words, the second piece 5b has a similar shape to the first piece 5a, and is flipped before being assembled on shaft 2 during assembly of mixer 1. In the design illustrated here, the first part 5a and the second part 5b are thus each composed of two blades 4a,4b arranged in opposition, and a support 3a, 3b connecting the two blades 4a, 4b.

[0093] Furthermore, the second part 5b is angularly offset relative to the first part 5a, such that the two parts 5a, 5b are not continuous with each other along the X-axis. The second part 5b is, for example, angularly offset by approximately 90° relative to the first part 5a, i.e., the second support 3b is angularly offset by 90° relative to the first support 3a. In particular, the two parts 5a, 5b are nested, i.e., they are assembled opposite each other on the shaft 2, the first portion 4a extending towards the second support 3b and the second portion 4b extending towards the first support 3a, the first portion 4a and the second portion 4b of the blade assembly 4a, 4b intersecting along a major part of their length. Thus, along this common length, along the X axis, all the blades 4a, 4b have a joint action. The [Fig.Figure 5 illustrates a cross-section of the mixer 1, along a portion of the X-axis in which all the blades 4a, 4b have a joint action.

[0094] In other examples, it is possible to design a single, monobloc element comprising the supports 3a, 3b and the blade assembly 4a, 4b, for example in the form of a "cage," or a structure similar to an assembly between the first part 5a and the second part 5b. It is also possible to design an assembly between the blades 4a, 4b and the supports 3a, 3b configured to allow adjustment of the orientation of the blades 4a, 4b relative to the supports 3a, 3b, in particular so as to adjust the inclination as described below.

[0095] Thus, the supports 3a, 3b and the blades 4a, 4b are assembled with the shaft 2 such that the rotational motion of the shaft 2 is transmitted to the supports 3a, 3b and to the blades 4a, 4b. In particular, the blades 4a, 4b are arranged so that their motion, when driven in rotation about the X-axis, forms a surface of revolution. The surface of revolution has the X-axis as its axis of revolution, the supports 3a, 3b form the longitudinal ends of the surface of revolution, specifically here two extremal faces, and the blades 4a, 4b, which extend between the supports 3a, 3b (with respect to the X-axis), form the lateral face of the surface of revolution. In particular, it is understood that the blades 4a, 4b are arranged at approximately the same distance from the shaft 2, so as to form the surface of revolution.The surface of revolution here corresponds to a cylinder of revolution, with supports 3a, 3b being perpendicular to the X axis and blades 4a, 4b being parallel to the X axis.

[0096] Obviously, depending on the shape and orientation of the supports 3a, 3b and the blades 4a, 4b, the surface of revolution can take other forms, in particular forms depending on the variants described above, for example, an elongated shape resulting from curved blades 4a, 4b. It is understood here that the surface of revolution, in particular the lateral face, forms a cage delimiting the action of the mixer 1 on the fluid. A variety of dimensions of the surface of revolution can also be provided, the dimensions of the surface of revolution depending directly on the dimensions of the blade assembly 4a, 4b, and optionally on the supports 3a, 3b. Preferably, the surface of revolution, in particular the cylinder of revolution described here, has a ratio between its maximum diameter (i.e. the diameter of the cylinder, or the distance between two opposite blades 4a, 4b) and its height (i.e. the distance between the supports 3a, 3b) of between 0.5 and 2.

[0097] In accordance with the underlying concept of the invention, namely the objective of a centripetal mixer 1, and as illustrated in [Fig. 5], the blades 4a, 4b move along a tangent M to the lateral surface, each blade 4a, 4b thus presenting a tangent M corresponding to its instantaneous motion, and each blade 4a, 4b being substantially inclined at an angle α with respect to the tangent M. The inclination is implemented so as to impart a force directed towards the axis X of the shaft 2, that is, a centripetal force. Obviously, the inclination depends on the direction of rotation, clockwise or counterclockwise around the axis X.

[0098] In particular, each blade 4a, 4b is substantially inclined, meaning that the angle α between the orientation of the blade 4a, 4b and the tangent M is relatively small. For example, an angle α of between 2° and 15° is expected. Such a design thus differs markedly from Rushton turbines, in which the blades are perpendicular to their motion. The Applicant submits that a small inclination makes it possible to obtain both high centripetal thrust and low drag at the blades 4a, 4b. Thus, the fluid is not driven in rotation around the X axis, this rotation being superfluous for the mixing, but is instead strongly driven towards the center of the mixer 1, i.e. in the direction of the X axis and the shaft 2. Each blade 4a, 4b thus creates a separate current, the currents intersecting around the X axis, generating turbulence and high shear.This design therefore reduces the energy consumed by mixer 1 while ensuring high shear, and thus high quality and homogeneity of the mixed fluid. Furthermore, since turbulence and shear occur at a distance from blades 4a and 4b, these blades are preserved and the service life of mixer 1 is increased.

[0099] It is also possible to adapt the shape and orientation of the blades 4a, 4b in order to adjust the properties of the mixer 1. In particular, the angle α can be adjusted, preferably within the range of 2° to 15°, a higher angle α resulting, in general, in greater shear but also greater drag and energy consumption.

[0100] In particular, the shape of the cross-section of the blades 4a, 4b can be optimized. Figure 5 illustrates a cross-section of the mixer 1 along a plane perpendicular to the X-axis. Figure 5 more precisely illustrates the cross-section of a first portion 4a or a second portion 4b of the blade assembly 4a, 4b, corresponding to a cross-sectional view of a specific portion of the mixer 1 in which the blades 4a, 4b do not intersect, or to a cross-sectional view of the first part 5a or the second part 5b. It is understood that the orientation of the blades 4a, 4b follows the same principle, regardless of their arrangement in the mixer 1.

[0101] In a simple design, the blades 4a, 4b have a substantially flat cross-section, each blade 4a, 4b simply extending in a direction inclined at angle a with respect to the tangent M.

[0102] In another, more elaborate design illustrated here, the cross-section defines a curved shape, that is, a non-planar shape. Such a curved shape advantageously corresponds to an airfoil, that is, a shape similar to the cross-section of an aircraft wing, so as to obtain the same advantages, the lift of an aircraft wing generating, in this case, a centripetal thrust of the fluid by the blade 4a, 4b, and the drag being ideally minimized in both cases. The airfoil thus has a biconvex or concave shape. A leading edge 6a, in contact with the fluid, and a trailing edge 6b, opposite the leading edge 6a, are also defined for an airfoil. Such a leading edge 6a advantageously has a rounded shape, and a trailing edge 6b a tapered shape.

[0103] The curved shape then exhibits an angle of incidence, i.e., an angle between a chord 6c of the curved shape and the fluid motion. The chord 6c corresponds to a straight line connecting the ends of the curved shape, and the fluid motion corresponds to the motion of the blade 4a, 4b, the angle of incidence of the curved shape corresponds to the angle a of inclination of the blade 4a, 4b with respect to the tangent M.

[0104] Advantageously, the supports 3a, 3b are also configured to form "axial" blades of the mixer 1, the movement of the supports 3a, 3b imparting an axial motion to the fluid, in addition to the radial motion imparted by the blades 4a, 4b. Thus, the movement of the supports 3a, 3b defines two extremal faces of the surface of revolution, the supports 3a, 3b each moving along a tangent to the extremal faces, and each support 3a, 3b being substantially inclined at an angle to the tangent of the extremal faces. In other words, each support 3a, 3b is substantially inclined with respect to the direction of its instantaneous motion. The inclination of supports 3a, 3b is implemented so as to impart a force along the X axis of shaft 2. In particular, the first support 3a is inclined so as to impart a force to the fluid in the direction of the second support 3b, and vice versa.

[0105] As illustrated in Figures 1 to 4, the supports 3a, 3b extend on either side of the X-axis, defining two portions symmetrical with respect to the X-axis and exhibiting opposite movement. The inclination of the supports 3a, 3b is also adjusted with respect to this symmetry so as to guarantee the direction imparted to the fluid along the supports 3a, 3b taking into account the clockwise or counterclockwise rotational movement of the shaft 2, in particular as illustrated in [Fig. 3] with respect to the second support 3b.

[0106] The rotation of shaft 2 then results in a joint movement of the blades 4a, 4b and the supports 3a, 3b, which impart to the fluid both a radial movement in the direction of the X-axis and an axial movement towards the center of shaft 2, that is, towards a median portion of shaft 2 along its length, equidistant from the supports 3a, 3b. All the currents converge around a central point of the mixer 1, that is, around an intersection of the X-axis and a median plane of the surface of revolution. Turbulence and shear are thus maximized at this point, at a distance from the blades 4a, 4b and the supports 3a, 3b.

[0107] Thus, it will be understood that the present invention provides for a high shear centripetal mixer, the profile of whose blades is optimized to obtain an advantageous combination between high shear and reduced energy consumption.

[0108] Such a mixer can thus be used in a variety of industries, and most preferably in the manufacture of precursors of active cathode materials. The high shear rate of the mixer ensures precursors with a very high quality and homogeneity of composition. The present invention therefore also covers the manufacture of precursors of cathode materials using such a mixer, and by extension, precursors of active cathode materials, as well as active cathode materials, obtained using such a mixer.

[0109] It should be noted that this detailed description relates to a particular embodiment of the present invention, but in no way does this description limit the scope of the invention; on the contrary, its purpose is to remove any possible inaccuracy or misinterpretation of the following claims.

[0110] It should also be noted that the reference signs in parentheses in the following claims are in no way intended to be limiting; these signs are solely intended to improve the intelligibility and understanding of the following claims and the scope of the protection sought.

Claims

Demands

1. High shear centripetal mixer (1) for fluid, which includes a shaft (2) extending along an axis (X) and configured to be driven in rotation about said axis (X), said mixer (1) further comprising: - two supports (3a, 3b) assembled on said shaft (2) and offset from each other along said shaft (2);and - a set of blades (4a, 4b) assembled on said supports (3a, 3b) so as to extend substantially parallel to said axis (X) of said shaft (2), at a distance from said shaft (2), so that the trajectory described by the movement of said blades (4a, 4b) forms a surface of revolution whose axis of revolution corresponds to said axis (X) of said shaft (2), said supports (3a, 3b) forming the longitudinal ends of said surface of revolution and said set of blades (4a, 4b) forming the lateral face of said surface of revolution, said blades (4a, 4b) each extending substantially inclined with respect to a tangent (M) of said lateral face, so as to impart to said fluid a force directed towards said axis (X) of said shaft (2).;

2. Mixer (1) according to claim 1, wherein said supports (3a, 3b) form two extreme faces of said surface of revolution, each of said supports (3a, 3b) being associated with one of said extreme faces and substantially inclined with respect to a tangent of said associated extreme face, so as to impart said fluid a force directed towards a central portion of said shaft (2).

3. Mixer (1) according to claim 1 or 2, wherein said supports (3a, 3b) extend perpendicularly to said axis (X) of said shaft (2), said blades (4a, 4b) extend parallel to said axis (X) of said shaft (2) so that said surface of revolution corresponds to a cylinder of revolution.

4. Mixer (1) according to any one of claims 1 to 3, wherein said blade assembly (4a, 4b) comprises at least one pair of blades (4a, 4b) arranged opposite each other with respect to said axis (X).

5. Mixer (1) according to any one of claims 1 to 4, wherein said supports (3a, 3b) and said blade assembly (4a, 4b) form a single unit.

6. Mixer (1) according to any one of claims 1 to 4, which comprises a first part (5a) and a second part (5b) both assembled with said shaft (2), said first part (5a) comprising a first of said supports (3a) and a first portion (4a) of said blade assembly and said second part (5b) comprising a second of said supports (3b) and a second portion (4b) of said blade assembly.

7. Mixer (1) according to claim 6, wherein said first part (5a) and said second part (5b) have an identical structure, said second part (5b) being symmetric to said first part (5a) along a median plane of said surface of revolution and having an angular offset with respect to said first part (5a).

8. Mixer (1) according to claim 6 or 7, wherein said first part (5a) and said second part (5b) are assembled on said shaft (2) such that said first portion (4a) and said second portion (4b) of said blade assembly overlap along the majority of their length.

9. Mixer (1) according to any one of claims 1 to 8, wherein, for at least one of said blades (4a, 4b), the cross-section along a plane perpendicular to said axis (X) of said shaft (2) defines a curved shape having an angle of incidence corresponding to the inclination of said blade (4a, 4b).

10. Mixer (1) according to claim 9, wherein, for at least one of said blades (4a, 4b), said curved shape corresponds to a profile having a leading edge (6a) and a trailing edge (6b), said profile defining said angle of incidence.

11. Mixer (1) according to any one of claims 1 to 10, wherein said blades (4a, 4b) of said third subassembly are inclined at an angle (a) between 2° and 15° with respect to said tangent (M) of said lateral face.

12. Mixer (1) according to any one of claims 1 to 11, wherein said blade assembly (4a, 4b) is dimensioned such that said surface of revolution formed by the movement of said blades (4a,

13.

14. 4b) has a ratio between its maximum diameter and its height of between 0.5 and 2. A mixer (1) according to any one of claims 1 to 12, which is designed for the manufacture of precursors of active cathode materials. Use of a high-shear centripetal mixer (1) according to any one of claims 1 to 13 for the manufacture of precursors of active cathode materials.

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