Product transfer system

Abstract

The present invention relates to a system (10) for transferring product, particularly in a vacuum processing chamber, said transfer system (10) comprising: - a body (12) defining a cavity (14), and - a transfer wheel (20) housed in said cavity (14) and provided with at least one pocket (28) at its periphery, the wheel (20) being adapted to rotate so as to convey product from said inlet zone (A) to said distribution zone (D), wherein the transfer wheel (20) and the body (12) cooperate to form a substantially airtight barrier between the two zones (A, D). The invention also relates to a processing system comprising such a transfer system and a corresponding processing method.

Description

Technical field

[0001] The present invention relates to the vacuum treatment of products, in particular products in powder form.

[0002] It relates in particular to a system for such treatment, in particular but not limited to a vacuum grinding system. State of the art

[0003] Grinding systems are commonly used in the food and pharmaceutical industries. The grinding chamber, in which the product is ground, is advantageously placed under vacuum to avoid altering the product's qualities through oxidation.

[0004] A grinding system is for example described in document CN 113 304 854 A. Furthermore, vacuum grinding systems are already known, for example from document FR 2 628 007. But these systems do not allow a satisfactory yield to be obtained or do not allow a certain oxidation of the product to be avoided, which alters its essential qualities.

[0005] The applicant has recently developed a continuous vacuum grinding system, operating using an inlet and outlet airlock system that can be evacuated and controlled by valves. The valve control allows a quantity of product to be ground to be transferred into the grinding chamber, which is kept permanently under vacuum. However, this system has the disadvantage of being relatively bulky.

[0006] The aim of the present invention is to propose an alternative system to the aforementioned system, which makes it possible to treat the product continuously and in an environment maintained under vacuum throughout the treatment operation. Disclosure of the invention

[0007] The idea behind the present invention is to take advantage, for the management of the vacuum in a treatment chamber, of the product distribution member typically

[0008] implemented in such a chamber. The treatment chambers are in fact provided, most of the time, with rotary or other type distribution members, allowing the treatment devices contained in said chambers to be supplied regularly and homogeneously. These distribution members, however, play no role in managing the pressure inside the chamber.

[0009] According to a first aspect, the invention relates to a system for product transfer, in particular for product transfer in a vacuum treatment chamber, according to claim 1.

[0010] By cooperating to form a substantially airtight barrier is meant that the maximum air flow rate between the intake zone and the distribution zone (between the wheel and the body) is less than or equal to 200 normo liters per minute (Nl / min), preferably less than or equal to 150 normo liters per minute (Nl / min), even more preferably less than or equal to 100 normo liters per minute (Nl / min).

[0011] To measure this maximum flow rate, for example, we can close the distribution zone and create a vacuum using a pump, and at the same time measure with a flow meter, in the intake zone, the quantity of air sucked through the wheel under the effect of the vacuum pump.

[0012] The passage of air between the intake zone and the distribution zone is prevented or substantially limited, so that a pressure difference between the two zones can be kept substantially constant or, at the very least, can vary in proportions sufficiently small to be compensated for by the use of a vacuum pump for example.

[0013] The transfer system according to the invention is, for example, particularly suitable for closing the inlet of a treatment chamber. The distribution zone then corresponds to the interior of said treatment chamber, which is advantageously under vacuum, in particular at an absolute pressure of between 0.05 and 0.3 bar. In this case, the inlet zone typically contains the product to be treated and, advantageously, forms the interior of a product reservoir, with the absolute pressure inside said reservoir typically equal to atmospheric pressure. In the context of such use, the transfer system allows the continuous supply of the treatment chamber, while ensuring the substantial maintenance of the pressure differential between the reservoir and the treatment chamber and therefore of the vacuum inside said treatment chamber.As previously stated, a slight air leak between the tank and the treatment chamber is not detrimental if it can be compensated for by using a vacuum pump in the treatment chamber. However, the maximum air flow between the two zones is preferably minimized as much as possible, or even reduced to zero.

[0014] The primary direction of the transfer system is the overall direction of product movement within the system. In operation, this direction is typically (but not limited to) the vertical direction, with the intake area located above the dispensing area.

[0015] For the entire present application, and in connection with the transfer wheel, an axial direction X is defined as a direction parallel to the axis of rotation X of the wheel.

[0016] A radial direction (for example Y) is also defined as a direction orthogonal to this axial direction.

[0017] A transverse plane is a plane normal to the axial direction.

[0018] The axis of rotation of the wheel is substantially orthogonal to the main direction, that is, it is inclined by at most 30 degrees relative to a plane normal to the main direction.

[0019] The wheel may be adapted to perform, around its X axis, either a continuous or alternating rotational movement. In other words, the wheel is not necessarily adapted to perform a complete revolution around its axis. In the case of an alternating movement, the rotational amplitude is sufficient so that the at least one pocket can be filled with product in the intake zone and emptied into the dispensing zone.

[0020] The transfer wheel is equipped with at least one pocket on its periphery, which can take very different shapes and dimensions.

[0021] By pocket, we mean here any compartment forming a hollow in relation to the radial surface of the wheel and adapted to receive product, in particular a powder.

[0022] Advantageously, the transfer wheel is provided at its periphery with a plurality of pockets regularly distributed on the radial surface of the wheel.

[0023] In the following, the useful radial surface of the wheel is understood to mean the section of surface radially circumscribing the wheel and in which the pockets are made.

[0024] According to one example, the surface of the wheel cooperates by shape complementarity with the internal surface of the body. In particular, advantageously, the useful radial surface of the transfer wheel cooperates by shape complementarity with a first radial interaction surface of the body on the side of its passage from the intake zone to the distribution zone and a second radial interaction surface of the body on the side of its passage from the distribution zone to the intake zone.

[0025] Advantageously, the curvilinear length, measured in a transverse plane, of each radial interface between the useful radial surface of the transfer wheel and a radial interaction surface of the body is at least equal to the maximum curvilinear length of the at least one pocket measured in a transverse plane.

[0026] When the wheel completes a complete revolution around its axis, each pocket of the transfer wheel thus passes through an intermediate entry sector where the pocket faces the first radial interaction surface and is entirely covered by said surface, and through an intermediate exit sector, where it faces the second radial interaction surface and is entirely covered by said surface.

[0027] The transfer system must be configured to prevent or substantially limit the circulation of air between the body and the transfer wheel. For this, the transfer wheel and the body may, for example, cooperate by dimensional adjustment and / or by a seal system. According to one example, the clearance between at least one of the first and second radial interaction surfaces and the useful radial surface of the transfer wheel may be made as small as possible, for example between 0.01 and 0.2 mm, preferably between 0.01 and 0.1 mm.

[0028] At the same time, the curvilinear length, measured in a transverse plane, of each radial interface between the useful radial surface of the transfer wheel and a radial interaction surface of the body is advantageously at least equal to 1 / 20 of the circumference of the wheel.

[0029] Alternatively or additionally, the wheel and body may cooperate by means of at least one seal to achieve airtightness.

[0030] Preferably, at least one linear seal, preferably two linear seals, extending in the axial direction of the transfer wheel, is / are arranged on at least one of the first and second radial interaction surface of the body or on the useful radial surface of the transfer wheel.

[0031] According to an advantageous arrangement, the at least two linear seals are, where appropriate, spaced apart by a curvilinear distance - measured in a transverse plane - at least equal to, preferably greater than, the maximum curvilinear length of a pocket of the wheel measured in a transverse plane. Such an arrangement ensures that each pocket always communicates with only one of the intake and distribution zones, including in a case where the body and the wheel are not dimensionally adjusted. Thus, two seals formed on a radial interaction surface of the body delimit between them and with the wheel a dynamic sealed airlock through which each pocket passes during rotation of the wheel. In the case of seals formed on the radial surface of the wheel, two seals located on either side of a pocket can cooperate with each radial interaction surface to form a dynamic sealed airlock.

[0032] To prevent the passage of air between the body and the lateral surfaces of the wheel, a circular seal may also be provided at each lateral end of said wheel. Circular seals may, for example, be arranged either on the external radial surface of the wheel, on either side of the useful radial surface, or on the lateral end surfaces of the wheel.

[0033] A joint system can, if necessary, be perfectly airtight.

[0034] However, even if the airflow between the body and the wheel is managed, in particular by means of one or the other solution described above or a combination of these solutions, a certain amount of air also passes through the pockets carrying the product. In particular, even when a pocket is full of powder, it always contains at least some amount of air.

[0035] Particularly advantageously, to prevent this air from entering the treatment chamber, the transfer system may comprise an air extraction system for extracting the air contained in the at least one pocket before it arrives in the distribution zone.

[0036] According to an exemplary implementation, this extraction system comprises at least one extraction conduit fluidically connected to a vacuum pump, and at least one filter to prevent the product from leaving the bag. The conduit is adapted to communicate with each bag to be emptied at least when this bag is located on the intermediate inlet sector, where it faces the first radial interaction surface of the body, in other words during its passage from the intake zone to the distribution zone.

[0037] Advantageously, the extraction duct can open onto said first radial interaction surface.

[0038] Alternatively, the extraction conduit may also be formed in the transfer wheel, the filter forming at least a portion of the bottom of said at least one pocket.

[0039] According to a second aspect, the invention relates to a system for vacuum treatment of a product, in particular a product in powder form, comprising: a frame, a treatment chamber delimited by the frame and capable of being fluidically connected to a vacuum pump, the treatment chamber being provided with an inlet for introducing the product to be treated and an outlet for discharging the treated product, a product transfer system as defined previously, arranged to close the inlet of the treatment chamber, and means for closing said outlet.

[0040] In one example, the processing chamber is a grinding chamber that includes a grinder.

[0041] According to one example, the treatment system may comprise a second transfer system as defined above, arranged to close the outlet of the treatment chamber. In this case, the product inlet zone is the interior of the treatment chamber and the distribution zone is a downstream zone where the product is recovered.

[0042] According to a third aspect, the invention also relates to a method for vacuum treatment of a product using a treatment system as defined above, comprising at least one step a) during which the following are carried out simultaneously: the rotation of the transfer wheel for the continuous supply of product into the treatment chamber previously placed under vacuum and the continuous treatment of the product supplied by the transfer wheel.

[0043] According to one example, step a) further comprises extracting air from each pocket of the transfer wheel before it arrives in the distribution zone.

[0044] According to another example, step a) further comprises aspirating air contained in the treatment chamber during the treatment of the product.

[0045] According to another example, during the entire step a), the absolute pressure differential between the intake zone and the treatment chamber is maintained between 0.7 and 0.95 bar.

[0046] According to another example, during step a), the absolute pressure inside the treatment chamber is maintained between 0.05 and 0.3 bar (with the absolute pressure outside the treatment chamber and therefore in the inlet zone of the transfer system at the inlet of the chamber advantageously equal to atmospheric pressure).

[0047] Other more specific aspects of the present invention are further described below: the inlet area may be a product reservoir, for example in the form of a hopper. In this case, the transfer wheel forms a wall of said product reservoir, and in particular its bottom wall, the reservoir, the transfer wheel and the treatment chamber may be vertically aligned, so that the at least one pocket is filled by gravity in the reservoir and emptied by gravity in the treatment chamber, at least one of the radial surface of the transfer wheel and the radial interaction surfaces may be made of a synthetic material, in particular PTFE, the pockets may be arranged in a staggered pattern on the useful radial surface of the wheel, the pocket(s) may be hemispherical in shape, the pocket(s) may extend in the axial direction, for example continuously over at least 50 percent of the axial length of the transfer wheel. Brief description of the drawings

[0048] Other details of the invention will appear more clearly on reading the following description, given with reference to the appended drawings in which: There figure 1 is an overall perspective view of a transfer system according to a first embodiment of the invention, The figure 2 is a partial perspective view of the transfer system of the figure 1 , according to a main cutting plane parallel to the axis of rotation of the transfer wheel, The figure 3 is a partial perspective view of the transfer system of the figure 1 , according to a main cutting plane orthogonal to the axis of rotation of the transfer wheel, The figure 4 is a partial view of the transfer system of the figure 1 , according to a principal section plane parallel to the axis of rotation of the transfer wheel, and on which the transfer wheel has been omitted to show the linear seals, The Figure 5shows a possible configuration of a radial seal at one side end of the wheel, The figure 6 shows the air exhaust system of the figure 3 , in section along the XY plane, The figure 7 is a partial view of a transfer system according to a second embodiment of the invention, according to a main section plane parallel to the axis of rotation of the transfer wheel, The figure 8 is a partial view of the transfer system of the figure 7 , according to a main cutting plane orthogonal to the axis of rotation of the transfer wheel, The figure 9 is a schematic view of a processing system according to the invention. Method of carrying out the invention

[0049] There figure 1 is an overview of a product transfer system 10 according to a first embodiment of the invention.

[0050] As visible on the figure 2, this transfer system 10 comprises a body 12 delimiting a cavity 14 extending in a main direction Z.

[0051] At its upper end 121, the body 12 forms a reservoir in the form of an inlet hopper 16 which can be filled with product. At its lower end 122, the body 12 has an opening 18 for the outlet of the product, through which it can be fixed, for example to a frame of a treatment system as will be described below with reference to the figure 9 .

[0052] A transfer wheel 20 (hereinafter wheel) is housed in the cavity 14.

[0053] Inside the cavity 14, in the main direction Z, the wheel 20 forms a separation between a product intake zone A and a product distribution zone D.

[0054] The product intake zone A is here the reservoir 16 formed by the hopper and the bottom of which is constituted by the radial surface 21 of the wheel 20.

[0055] The distribution area D may, in use, be the interior of a product treatment chamber.

[0056] The transfer wheel 20 is here secured to a shaft 24 adapted to rotate around its axis X under the action of a drive motor 25 visible on the figure 1 , thanks to a set of bearings 26, 27.

[0057] The transfer wheel 20 here has the shape of a straight cylinder, as is particularly evident from the figure 3 .

[0058] It is thus delimited radially by a radial surface 21, and axially by a first lateral end surface 22 and a second lateral end surface 23 (hereinafter end surfaces 22, 23) which are substantially planar, orthogonal to the axis of rotation X.

[0059] According to alternative embodiments, however, the transfer wheel could have a different shape, such as a spherical or ovoidal shape. In such cases, the radial surface of the wheel could correspond to the entire surface of the wheel 20.

[0060] As illustrated on the figures 2 And 3 in particular, the wheel 20 comprises, on a part of its radial surface 21 called the useful radial surface 211, a plurality of hollow pockets or compartments 28. These pockets 28 are intended to be filled with product in the intake zone A and to be emptied of their contents in the distribution zone D.

[0061] In order to ensure a regular and substantially homogeneous distribution of product in the distribution zone D, the pockets 28 are advantageously distributed regularly over the entire useful radial surface 211 of the wheel 20.

[0062] In the particular example considered, each pocket 28 has a hemispherical shape, and the pockets are arranged in a staggered pattern.

[0063] The wheel 20 cooperates by complementarity of shape with the internal surface 13 of the body 12.

[0064] In particular, the useful radial surface 211 of the wheel, carrying the pockets 28, cooperates by complementarity of shape with a first radial interaction surface 131 of the body 12 on the side of its passage from the intake zone A to the distribution zone D and with a second radial interaction surface 132 on the side of its passage from the distribution zone D to the intake zone A (see direction of rotation f on the figure 3 ).

[0065] By cooperating by complementarity of shape, it is meant in the present application that the elements concerned have corresponding shapes. On either side of the wheel 20, in the radial direction Y orthogonal to X and Z, the body 12 thus matches the curvature of the wheel 20 so that the radial gap between the body and the useful radial surface 211 has a substantially constant width in the Y direction over its entire length in the Z direction.

[0066] In a transverse plane of the distribution wheel, the curvilinear length C131, respectively C132 of the radial interface between the transfer wheel 20 and each radial interaction surface 131, 132 is strictly less than half the circumference of the wheel 20.

[0067] At the same time, the curvilinear length C131, C132 of the radial interface between the transfer wheel 20 and each radial interaction surface 131, 132, measured in a transverse plane, is at least equal to the maximum curvilinear length C28 of each pocket 28 measured in a transverse plane. In this way, when the wheel 20 makes a complete revolution around its axis X, each pocket 28 of the wheel 20 passes through an intake sector SA where it faces the intake zone A, an intermediate inlet sector SE where it faces the first radial interaction surface 131 of the body 12 and is entirely covered by said surface 131, a distribution sector SD where it faces the distribution zone D and an intermediate outlet sector SS, where it faces the second radial interaction surface 132 and is entirely covered by said surface 132 (see figure 3 ).

[0068] In the particular example illustrated and as visible on the figure 2 , each end surface 22, 23 of the wheel 20 also cooperates by complementarity of shape with an axial interaction surface respectively 133, 134 of the body.

[0069] In the system according to the invention, the body 12 and the wheel 20 cooperate to form a substantially airtight barrier between the intake zone A and the distribution zone D.

[0070] This sealing, which must be ensured when stationary as well as during rotation of the wheel 20, is achieved at two levels: On the one hand, air is prevented from circulating at the interface between the wheel 20 and the body 12.

[0071] In the embodiment of the figure 1 , the body 12 and the wheel 20 are therefore dimensionally adjusted.

[0072] The clearance between each radial interaction surface 131, 132 of the body 12 and the useful radial surface 211 of the transfer wheel 20 is minimized, and preferably between 0.01 and 0.2 mm, preferably between 0.01 and 0.1 mm.

[0073] The same is preferentially true of the clearance between each end surface 22, 23 of the wheel 20 and the axial interaction surface 133, 134 of the body 12 opposite.

[0074] Also, the curvilinear length C131, C132 of the interface between the transfer wheel 20 and each radial interaction surface 131, 132 is preferably equal to at least 1 / 20 of the circumference of the wheel 20.

[0075] The interface between each interaction surface 131, 132, 133, 134 of the body and the useful radial surface 211 of the wheel 20 is thus sufficiently narrow and long so that the pressure gradient at the interface is as high as possible. In this way, the pressure losses at the interface are then sufficient to prevent the passage of air.

[0076] The curvilinear length of the interface also being greater than that of a pocket 28 as indicated previously, preferably equal to at least twice the maximum curvilinear length of the pocket 28 measured in a transverse plane, the wheel 20 and the body 12 are arranged so that each pocket 28 communicates simultaneously only with one or the other of the intake zone A and the distribution zone D.

[0077] With such an adjustment of the parts, in order to avoid pollution of the product by wear particles resulting from friction between the transfer wheel and the body, it is advantageous that at least one of the wheel 20 and the interaction surfaces 131, 132, 133, 134 is made of a synthetic material, in particular polytetrafluoroethylene (PTFE).

[0078] The body can for example be made of ceramic or metal, and the wheel 20 of PTFE.

[0079] Advantageously, as in the example of the figures 1 to 4 , the precise adjustment of the wheel 20 and the body 12 is further reinforced by the presence of seals at the interface between the two parts.

[0080] As illustrated on the figures 3 And 4, each radial interaction surface 131, 132 here carries two linear seals 411, 412, respectively 421, 422, extending in the axial direction X over a length at least equal to the axial length of the useful radial surface 211 of the wheel 20 and configured to cooperate with said useful radial surface 211. These seals are advantageously scraper seals. The two seals 411, 421, respectively 421, 422 of the same pair are spaced apart by a curvilinear distance C41 respectively C42 - measured in a transverse plane - at least equal to, preferably greater than, the curvilinear length C28 of a pocket 28 of the wheel 20 measured in a transverse plane. Such an arrangement ensures that each pocket 28 always communicates with only one of the intake A and distribution D zones, including in a case where the body 12 and the wheel 20 are not dimensionally adjusted.

[0081] According to an alternative arrangement, a plurality of linear seals could also be provided on the radial surface 21 of the transfer wheel 20, regularly distributed around its circumference, and configured to cooperate with the radial interaction surfaces 131, 132 of the body to achieve sealing.

[0082] A circular seal 431, 432 (forming a closed contour in a transverse plane of the wheel, see figures 5 And figure 7 ), can also be provided at each lateral end 201, 202 of the wheel 20.

[0083] As illustrated in the Figure 5, the lateral ends 201, 202 of the wheel 20 can be inserted over a short axial length, in a corresponding part of the body 12. In other words, at each lateral end 201, 202 of the wheel 20, the external radial surface 212 of the wheel 20 cooperates by complementarity of shape with a cylindrical internal surface 135, 136 of the body 12. A radial seal 431, 432 mounted on the periphery of the wheel 20 can thus cooperate radially with said internal cylindrical surface 135, 136 opposite.

[0084] There Figure 5illustrates the arrangement of a circular seal 431 at the lateral end 201 of the wheel. The circular seal 431 is here a lip seal, with a substantially L-shaped section. It could however be an O-ring or any other suitable type of seal. According to the arrangement illustrated, a first flat annular part 4311 of the seal is fixed to the lateral end surface 22 of the wheel 20 by means of a washer 441 applied against said first part 4311 on the one hand and against said end surface 22 on the other hand and fixed on said surface by screws 451. A second cylindrical part 4312 of the seal, extending said first part, forms a lip projecting relative to the useful radial surface 211 of the wheel and adapted to be applied by deforming against the internal surface 135 of the body. The elasticity of the lip forces it against the surface of the body, thus ensuring a seal.

[0085] Alternatively, a circular seal could be provided on each lateral end surface 22, 23 of the wheel 20, to cooperate with a surface 133, 134 of the body 12 located opposite.

[0086] In the first embodiment described above, the sealing between the surface of the wheel 20 and the body 12 is achieved by a dimensional adjustment of the parts and by a set of seals. According to an alternative embodiment, the sealing could also be achieved solely by a dimensional adjustment of the parts, or solely by a set of seals, or by a different combination than that described in connection with the first embodiment (for example: the dimensional adjustment could be omitted between the lateral end surfaces of the wheel 20 and the body 12 opposite).

[0087] Even if the air flow between the body 12 and the wheel 20 is managed, in particular by dimensional adjustment of the two parts or by a system of sealing joints or a combination of these solutions, a certain quantity of air also passes through the pockets 28 transporting the product. In particular, even when a pocket 28 is full of powder, it always contains at least a certain quantity of air.

[0088] Particularly advantageously, to prevent this air from entering the distribution zone (which is generally a vacuum treatment chamber), the transfer system 10 comprises an air extraction system 50 for extracting the air contained in the at least one pocket 28 before it arrives in the distribution zone D.

[0089] In the illustrated example, as seen in particular on the figure 3, the extraction system 50 is integrated into the body 12: it comprises an extraction conduit 51 opening into the cavity 14 and fluidically connected to a vacuum pump not shown, and a filter 52 to prevent the product from leaving the pocket, forming part of the first radial interaction surface 131.

[0090] The conduit 51 is adapted to communicate with each pocket 28 to be emptied when this pocket is located on the intermediate inlet sector SE, where it faces the first radial interaction surface 131, in other words during its passage from the intake zone A to the distribution zone D.

[0091] In order to be able to vacuumize all of the pockets 28 of the wheel 20 during rotation of the latter, the conduit 51 comprises at least one section of length - measured in axial direction X - substantially equal to the axial length of the useful radial surface 211 over which the pockets 28 of the wheel 20 extend. As can be seen in the figure 6 , the conduit 51 comprises such a section 511 terminated by the filter 52 and extended by a second section of reduced diameter allowing connection to the vacuum pump.

[0092] When a pocket 28 arrives opposite the conduit 51, on the inlet sector SE, it no longer communicates with the intake zone A, and does not yet communicate with the distribution zone D. Either the clearance between the body and the wheel prevents the passage of air between the zones A and D and the pocket 28, or axial sealing joints 411, 412 are arranged on either side of the pocket 28 and on either side of the conduit 51 so as to form a sealed intermediate airlock between the two zones A and D, or both.

[0093] The air contained in the pocket 28 is then sucked out under the action of the vacuum pump. The product is stopped by the filter 52 and thus remains inside the pocket 28.

[0094] As an alternative or in addition, an extraction conduit could also be integrated into the transfer wheel 20, the filter forming at least part of the bottom of each pocket 28.

[0095] THE figures 7 And 8illustrate a transfer system according to a second embodiment of the invention, similar to that described in connection with the figures 1 to 6 but in which the pockets are of different shapes. All reference numerals referring to elements identical or similar to the elements described above are numbered with the same references in these figures and are not described again.

[0096] In this example, as seen on the figure 7 , each pocket 29 is in the form of an elongated groove, extending in the axial direction X of the wheel 20. More specifically, each pocket extends in the axial direction over a length L2 equal to at least 50% of the axial length L1 of the wheel 20.

[0097] In cross section, as shown in the figure 8 , the pockets have for example a profile that flares outwards, roughly in the shape of a V.

[0098] There figure 9schematically illustrates a treatment system 100 comprising a treatment chamber 90 and at least one transfer system 10 according to the invention for supplying this chamber 90.

[0099] The treatment chamber 90 is delimited by a frame 93. It comprises an inlet 91 for the introduction of the product P to be treated, and an outlet 92 for the evacuation of the treated product.

[0100] In this case, the inlet 91 of the treatment chamber 90 is located in the vicinity of the upper end of this chamber 90 and the outlet 92, in the vicinity of its lower end.

[0101] The inlet 91 of the treatment chamber is closed by the first transfer system 10a according to the invention, the wheel of which acts as a metering device.

[0102] According to an advantageous arrangement, the outlet 92 of the chamber 90 is closed by a second transfer system 10b according to the invention. Alternatively, the outlet 92 of the chamber 90 could also be closed by a sealed valve or by an airlock closed by two valves, the evacuation of the product not necessarily being carried out continuously.

[0103] The treatment chamber 90 houses at least one device 94 for treating the product. The product to be treated is, for example, a powder, formed of grains with a maximum diameter of, for example, between 100 and 1000 microns.

[0104] According to an example of use, the chamber 90 is for example a grinding chamber and this treatment device 94 is a grinder. In the case of a powder of the aforementioned type, the grinder 94 is for example adapted to obtain after treatment a maximum grain diameter of for example between 10 and 100 microns.

[0105] In the particular example illustrated, the product distributed into the treatment chamber 90 by the first transfer system 10a falls by gravity into the treatment device 94 located below, then towards the outlet 92.

[0106] The interior of the treatment chamber 90 communicates with a vacuum pump 97 by a conduit 95 opening onto an opening 96 of the chamber 90. To prevent the suction of product when the pump 97 is in operation, the opening 96 can be protected by a filter system 99.

[0107] In the processing system described above in connection with the figure 9 , the treatment chamber 90 is preferably placed under vacuum, at an absolute pressure of between 0.05 and 0.3 bar during the product treatment operation. This vacuum makes it possible to avoid deterioration of the product by oxidation and to limit the risks of explosion in the case of an inflammable product.

[0108] The tank 16 - which forms the product intake zone A for the first system 10a - is open to the outside, and therefore typically at atmospheric pressure.

[0109] The system 10a closes the inlet 91 of the treatment chamber so as to allow it to be placed under vacuum and to maintain this vacuum, while allowing the continuous distribution of product P inside the chamber 90.

[0110] In the same way, the second transfer system 10b makes it possible to evacuate the treated product to a downstream receiving device 98 while ensuring sufficient airtightness for placing and maintaining the chamber 90 under vacuum.

[0111] The use of such a treatment system is as follows: The treatment chamber is evacuated using the vacuum pump 97.

[0112] Tank 16 is filled with product to be treated.

[0113] The transfer wheel 20 of the first transfer system is rotated using the drive motor 25. By gravity, the pockets 28 of the wheel 20 are filled with product P. Advantageously, the air extraction system 50 is activated to create a vacuum inside each pocket before it arrives in the treatment chamber.

[0114] At the same time, the treatment device is operated to be able to immediately and continuously treat the product P distributed by the wheel 20.

[0115] If necessary, the transfer wheel of the second system 10b is simultaneously rotated to continuously evacuate the treated product to a downstream receiving device 98.

[0116] If the distribution systems 10a and 10b are perfectly sealed, for example thanks to the use of a set of seals as described previously, the chamber remains under vacuum throughout the duration of the treatment, in particular thanks to the air extraction systems 50 which create an intermediate vacuum of each pocket between the reservoir 16 and the treatment chamber 90, respectively between the treatment chamber 90 and the outside of the chamber.

[0117] If either of the distribution systems 10a, 10b allows a certain quantity of air to pass, between the body and the wheel and / or via the pockets, then the method comprises compensating for this air ingress by activating the vacuum pump 97 during the treatment operation.

Claims

1. System (10) for transferring product (P), said transfer system (10) comprising: - a body (12) defining a cavity (14) extending in a main direction (Z), the transfer system (10) being characterized in that it comprises - a transfer wheel (20) accommodated at least partially in said cavity (14) and separating in said main direction (Z) a product intake zone (A) and a product distribution zone (D), the transfer wheel (20) being provided with at least one pocket (28, 29) at its periphery and being adapted to rotate about an axis (X) substantially orthogonal to said main direction (Z) so that said pocket (28, 29) feeds product from said intake zone (A) to said distribution zone (D), the transfer wheel (20) and the body (12) co-operating to form a substantially air-tight barrier between the intake zone (A) and the distribution zone (D).

2. Transfer system (10) according to claim 1, wherein the transfer wheel (20) and the body (12) co-operate by dimensional fit and / or by a seals system to form said substantially air-tight barrier.

3. The transfer system (10) according to claim 1 or 2, comprising an air extraction system (50) for extracting air contained in the at least one pocket (28, 29) prior to its arrival in the distribution zone (D).

4. Transfer system (10) according to claim 3, wherein the extraction system (50) comprises at least one extraction conduit (51) fluidly connected with a vacuum pump, and at least one filter (52) to prevent product from exiting the pocket (28, 29).

5. Transfer system (10) according to claim 4, wherein the extraction conduit (51) is formed in the transfer wheel (20), and the filter (52) forms at least a portion of the bottom of said at least one pocket (28, 29).

6. Transfer system (10) according to any one of claims 1 to 5, wherein a useful radial surface (211) of the transfer wheel (20) co-operates in a form-fitting manner with a first radial interaction surface (131) of the body (12) on the side of its passage from the intake zone (A) to the distribution area (D) and a second radial interaction surface (132) of the body (12) on the side of its passage from the distribution zone (D) to the intake zone (A).

7. Transfer system (10) according to claim 6, wherein the curvilinear length (C131, C132), measured in a transverse plane, of each radial interface between the useful radial surface (211) of the transfer wheel (20) and a radial interaction surface (131, 132) is at least equal to the maximum curvilinear length (C28) of the at least one pocket (28) measured in a transverse plane.

8. Transfer system (10) according to claim 6 or 7, wherein the clearance between at least one of the first and second radial interacting surfaces (131, 132) of the body (12) and the useful radial surface (211) of the transfer wheel (20) is between 0.01 and 0.2mm, preferably between 0.01 and 0.1mm.

9. Transfer system (10) according to any one of claims 6 to 8, wherein the curvilinear length (C131, C132), measured in a transverse plane, of each radial interface between the useful radial surface (211) of the transfer wheel (20) and a radial interaction surface (131, 132) of the body (12) is at least equal to 1 / 20 of the circumference of the wheel (20).

10. Transfer system (10) according to claim 4 or 5 and any one of claims 6 to 9, wherein the extraction conduit (51) opens onto said first radial interaction surface (131) of the body (12).

11. Transfer system (10) according to any one of claims 1 to 10, wherein at least one linear seal (411, 412, 421, 422), preferably at least two linear seals, extending in the axial direction (X) of the transfer wheel (20), is arranged on at least one of the first and second radial interaction surfaces (131, 132) or on the useful radial surface (211) of the transfer wheel (20).

12. Transfer system (10) of any one of claims 1 to 11, wherein the transfer wheel (20) is provided with a plurality of pockets (28) arranged in a staggered pattern and evenly distributed around its circumference.

13. System (100) for processing a product (P) under vacuum, in particular a product in powder form, comprising: - a frame (93), - a processing chamber (90) delimited by the frame (93) and capable of being connected in fluid connection with a vacuum pump (97), the processing chamber (90) being provided with an inlet (91) for the introduction of product to be processed (P) and an outlet (92) for the discharge of the processed product, - a product transfer system (10) according to any one of claims 1 to 12, arranged to close the inlet (91) of the processing chamber (90), and - means for closing said outlet (92).

14. Processing system (100) according to claim 13, wherein the processing chamber (90) is a grinding chamber that includes a grinder.

15. Processing system (100) according to claim 13 or 14, comprising a second transfer system (10b) according to any one of claims 1 to 11 arranged to close the outlet (92) of the processing chamber (90).

16. Method of vacuum processing of a product (P) by means of a processing system (100) according to any one of claims 13 to 15, comprising at least one step a) during which are simultaneously performed: - the rotation of the transfer wheel (20) for the continuous supply of product (P) into the processing chamber (90) previously put under vacuum, and, - the continuous processing of the product (P) fed by the transfer wheel (20).

17. Processing method according to claim 16, wherein step a) further comprises the removing of air in each pocket (28, 29) of the transfer wheel (20) prior to its arrival in the distribution area (D).

18. The processing method according to claim 16 or 17, wherein step a) further comprises a suctioning of air contained in the processing chamber (90) during processing of the product.

19. The processing method according to any one of claims 16 to 18, wherein throughout step a) the absolute pressure differential between the intake zone (A) and the processing chamber (90) is maintained between 0.7 and 0.95 bar.

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