EP2750808B1 - Method and device for separating products - Google Patents

Description

Technical field of the invention

The invention relates to the field of the separation of products in refusals and passers-by, whether it is sieving in the case of products in the form of powders or dry granules or filtration in the case of products in the form of fluids ( liquids and / or gases).

The invention more particularly relates to a product separation device and an apparatus comprising one or more such devices, as well as a method of separating products using such an apparatus.

State of the art

In many areas, it is necessary to achieve a separation of products by passers-by and refusals, according to a threshold value of size. This is particularly the case in the field of powders or granules, whether in particular but not exclusively micron and submicron type, mineral, metal, ceramic and organic.

Conventionally, a product separation apparatus or machine uses one or more separation devices, each characterized on a given retention size. Each device comprises a structure supporting a filtering element or screening type wire mesh or grid or even electro-formed perforated sheet, and is mounted on a rigid frame. The separation of products is effected by moving the filter element or sieving relative to the products to be separated.

Known techniques use mechanical means to move the filter element in order to distribute the products to be separated and / or to scrape the products along the filter element, like the solutions described in the documents. WO2008124441A1 , JP6320111A , JP2000246178A .

These solutions are not always completely satisfactory because it is well known that they have, in many cases, a strong tendency to clog the filter elements. It is for this reason that ultrasonic vibration assistance techniques have been developed that are used in addition to mechanical means, just like the solutions described in the documents. FR2671743A1 , US7694826B2 , DE202005005847U1 , WO2008040540A1 and US7497338B2 . The document US 2006/0266284 A1 It has an apparatus in which the screen is directly vibrated by an ultrasonic transducer.

However, all these solutions are in many cases unsatisfactory in terms of extraction rate desired particle size, reproducibility and internal retention of products.

Similar problems affect the field of fluids during filtration operations.

Object of the invention

The object of the present invention is to provide a product separation solution that overcomes the disadvantages listed above.

A first object of the invention is to provide a product separation solution, by sieving or filtration, which ensures an optimum reproducible extraction rate in perfect adaptability.

A second object of the invention is to provide a product separation solution, by sieving or filtration, silent, without mechanical movement and requiring simple adjustments, which allows continuous operation, that is to say without any need for specific operation to evacuate refusals and without internal retention zones of products.

A third object of the invention is to provide a product separation solution, by sieving or filtration, for which the products to be separated are previously organized to feed the entire width of the filter element or sieving and whose only energy is provided by means of ultrasonic waves.

For this purpose, a first aspect of the invention relates to a product separation device comprising a structure vibrated by an electroacoustic converter and supporting a filter element or sieving. The assembly is configured so that the separation of products passersby through the filter element or sieving and refusal results solely from ultrasonic vibrations of the filter element or sieving induced by the vibration of the structure by the converter Electroacoustic.

The assembly can be configured so that the discharge of the refusals out of the filtering or sieving element results solely from the effect of gravity to allow separation of products and evacuation of continuous refusals without constituting zones of internal retentions of products.

The device may comprise an input zone intended to be fed with products to be separated, the pre-distribution of which allows feeding in a continuous curtain over its entire width and an exit zone of the refusals after separation and to be configured so that the filtering or sieving element, under the effect of ultrasonic vibrations transmitted by the structure, generates a flow of the products being separated from the inlet zone to the exit zone by allowing passersby to pass through the filtering or sieving element during this flow.

The entrance zone may be located at a height greater than that of the exit zone.

The filtering or sieving element may be generally flat and inclined with respect to the horizontal, the inlet zone being provided near a high edge of the filter element or sieving and the exit zone being provided in the vicinity of a bottom edge of the filtering or sieving element, the direction of flow being oriented from the top edge to the bottom edge.

The device may comprise an element for adjusting the inclination of the filter element or sieving in a given range of a few degrees, for example between 0 ° and 10 °, to adjust the flow velocity of the products in process. separation according to their ability to flow.

Since the filtering or sieving element is attached to the structure at least at the exit zone, the bonding surface at the outlet between the filtering or sieving element and the structure may be in a plane different from the the filter element or sieving, the edge of the exit zone may be on the same plane as the structure or 0.2 millimeters to a few millimeters below.

The emission of ultrasonic vibrations to the structure can be performed in pulsed mode.

The electroacoustic converter can be connected to the structure at the entrance area by means of fasteners.

A second aspect of the invention relates to an apparatus comprising at least one product separation device as mentioned above secured to a rigid chassis by connecting elements, the apparatus comprising a feeding device for discharging products. to be separated on the filtering or sieving element from the separation device.

The connecting elements between the separating device and the rigid chassis may comprise at least one seal, in particular integral with the structure of the separation device, interposed between the structure and a contact surface of the rigid chassis, and configured so that to absorb the ultrasonic vibrations of the structure without heating.

The connecting elements between the separating device and the rigid chassis may comprise at least one clamping member, in particular a compression spring, configured to clamp the separating device against the contact surface of the rigid chassis by compressing the seal in a manner limiting or even avoiding the transmission of ultrasonic vibrations to the rigid chassis.

The feed device can ensure a spill of the products over the entire width of the filter element or sieving, especially in the form of a curtain of products of constant thickness.

The apparatus may include an element for containing the discharged refusals out of the filtering or sieving element and / or a plurality of separating devices configured and superimposed on top of each other so as to have decreasing retention gauges going from above below, the products to be separated supplying a given separation device other than the most above being constituted by the loops of the separation device directly above.

A third aspect of the invention relates to a method of separating products using an apparatus as mentioned above, comprising a step of separating the products by passers-by through the filtering or sieving element and refusals resulting solely from ultrasonic vibrations. of the filter element induced by the vibration of the structure by the electroacoustic converter.

The product separation step can be carried out by flowing the products to be separated along the filtering or sieving element of the filtration device, with a dispersion of the constituents of the loops passing through the filter element or sieving according to a gradation gradient increasing in the direction of flow.

Finally, it can be provided an adjustment of the flow length of the products to be separated according to a desired upper threshold of granulometry passers.

Brief description of the drawings

• la figure 1 est une vue de dessus d'un exemple de dispositif de séparation de produits selon l'invention,
• la figure 2 illustre la coupe A-A de la figure 1,
• la figure 3 représente la coupe B-B de la figure 2.

Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention given as non-restrictive examples and shown in the accompanying drawings, in which:

• the figure 1 is a top view of an example of a product separation device according to the invention,
• the figure 2 illustrates the AA cut of the figure 1 ,
• the figure 3 represents the BB cup of the figure 2 .

Description of preferred modes of the invention

The present description will be limited essentially to explanations relating to a separation consisting of a sieving operation of powders or granules, without this having to be interpreted as a limitation of the object of the present invention which, on the contrary, also finds application for a filtration operation of products in the form of a fluid, of the liquid or gas type.

On the figure 1 is illustrated a product separation device 10 comprising a structure 11 vibrated by an electroacoustic converter 12 and supporting a filter element or sieving 13. The device 10 is intended to form a sieve in the case of sieving operations powders or granules, or a filter in the case of filtration operations of a liquid or a gas. In all cases, it is a question of separating, thanks to the filtering or sieving element 13 thus vibrated by the structure 11, the products in refusals and bystanders according to retention gauges corresponding to the size of the products. above which they constitute the refusals that are to be evacuated. On the contrary, bystanders, by vibrating the filter element or sieving 13, are intended to pass through the latter being smaller than the retention size.

The filtering or sieving element 13 may be constituted by any suitable solution depending on the products to be separated, such as a fabric metal or a grid or a sheet electro-formed perforated.

According to an important characteristic, all the elements which constitute the device 10 are configured so that the separation of products by passers-by through the filtering or sieving element 13 and refusals results solely from the ultrasonic vibrations of the filter element or sieving 13 induced by the vibration of the structure 11 by the electroacoustic converter 12. Thus the separation of the products is obtained without mechanical movement and without input of energy other than that corresponding to ultrasound.

• d'une plaque d'aluminium ou autre métal conduisant les ultrasons sans perte d'amplitude ni d'amortissement, cette plaque étant par exemple usinée dans la masse,
• d'une structure tubulaire métallique soudée ou mécano-soudée ou collée ou montée par assemblage mécanique,
• d'une structure partiellement usinée et partiellement tubulaire assemblée selon les moyens ci-dessus.

It is in particular a structure 11 not tuned, in that it is not designed to have a resonance frequency equal to multiple of the excitation frequency delivered by the converter 12. On the contrary, the structure 11 can be any, made from:

• an aluminum plate or other metal conducting the ultrasound without loss of amplitude or damping, this plate being for example machined in the mass,
• a tubular metal structure welded or mechanically welded or glued or assembled by mechanical assembly,
• a partially machined and partially tubular structure assembled according to the means above.

The assembly is configured so that the evacuation of refusals out of the filtering or sieving element 13 results solely from the effect of gravity to allow a separation of the products and an evacuation of the refusals which are continuous, all without constituting any internal retention area of the products. Thus the device 10 allows a natural and permanent evacuation of refusals and bystanders, freeing themselves from any need for spilling, scraping or brushing the filtering or sieving element 13.

In order to achieve these very advantageous results, the device 10 comprises, for example, an inlet zone 14 intended to be fed with products to be separated beforehand organized to feed the entire width of the filtering or sieving surface and an outlet zone 15 for evacuating refusal after separation. The assembly is configured so that the filtering or sieving element 13, under the effect of the ultrasonic vibrations transmitted by the structure 11 itself put into vibration by the converter 12, generates a flow of the products being separated from the inlet zone 14 to the exit zone 15 allowing through passers through the filter element or sieve 13 during this flow. In particular, the input zone 14 may be located at a height greater than that of the exit zone 15 so that the flow is unidirectional as illustrated by the arrow 16 on the figure 1 . The actual separation zone is interposed between the inlet and outlet zones 15, consisting of the filtering or sieving element 13. It is at the exit zone 15 that the refusals are permanently evacuated. and natural by the simple effect of gravity without constituting any area of internal retention of products.

By virtue of this flow 16 of the products generated by the only ultrasonic vibrations transmitted to the filtering or sieving element 13 by the structure 11, the distribution function of the products is combined with the sieving function (or filtration) proper. Thus all the energy transmitted to the device 10 is used by sieving (or filtration), unlike the prior art where a fraction of the energy is used for the distribution of products.

• Le transfert de l'énergie de vibration ultrasonore vers les produits à tamiser ou filtrer se fait par choc ou par effet catapulte. L'effet de ce transfert d'énergie est de propulser verticalement (vers le haut ou vers le bas) la majorité des particules de produits, celles-ci atteignant des hauteurs différentes selon leur diamètre, leur masse, le diamètre du fil utilisé, l'amplitude de la vibration et la fréquence de vibration ultrasonore appliquée. L'énergie d'un fil vibrant de l'élément filtrant ou tamisant 13 dépend de sa masse et du carré de sa vitesse de déplacement. La masse dépend du diamètre du fil, les fils habituellement utilisés ayant un diamètre variant de 20 à 50 µm environ par exemple, soit une variation de masse avec un rapport de 1 à 6,25 par unité de longueur. Les particules à séparer ont un diamètre variable, par exemple variant de 25 à 50 µm, soit une variation de masse avec un rapport de 1 à 8. Les éléments filtrant ou tamisant 13 les plus fins destinés à la séparation des plus petites particules utilisent des fils de plus petit diamètre, ces particules plus fines reçoivent donc de moins en moins d'énergie sauf à augmenter de manière importante l'amplitude des vibrations appliquées au fil. L'amplitude de vibrations du fil ne peut être augmentée sans risque de sa rupture en raison des contraintes exercées qui pourraient excéder la limite d'élasticité du matériau et des frictions à très grande vitesse existant entre les fils. Ces frictions risquent de causer une usure très rapide des fils, voire une fusion. Cette énergie transmise aux produits permet de disperser, répartir, la couche de produits présente à la surface de l'élément filtrant ou tamisant 13 et donc de dégager ses orifices pour permettre le passage des particules plus petites que ces orifices à travers l'élément 13.

Flow and separation are based on the following physical principles:

• The transfer of ultrasonic vibration energy to the products to be screened or filtered is by shock or catapult effect. The effect of this energy transfer is to propel vertically (upwards or downwards) the majority of the product particles, which reach different heights according to their diameter, their mass, the diameter of the wire used. amplitude of the vibration and the frequency of ultrasonic vibration applied. The energy of a vibrating wire of the filtering or sieving element 13 depends on its mass and the square of its speed of displacement. The mass depends on the diameter of the wire, the son usually used having a diameter ranging from about 20 to 50 microns, for example, a mass variation with a ratio of 1 to 6.25 per unit length. The particles to be separated have a variable diameter, for example ranging from 25 to 50 μm, ie a mass variation with a ratio of 1 to 8. The finer filtering or sieving elements 13 intended for the separation of the smaller particles use son of smaller diameter, these finer particles therefore receive less and less energy except to significantly increase the amplitude of the vibrations applied to the wire. The vibration amplitude of the wire can not be increased without the risk of its breaking due to the stresses that could exceed the limit of elasticity of the material and friction at very high speed existing between the son. These frictions may cause very rapid wear of the threads or even a fusion. This energy transmitted to the products makes it possible to disperse and distribute the layer of products present on the surface of the filtering or sieving element 13 and thus to disengage its orifices to allow the passage of particles smaller than these orifices through the element 13. .

Moreover, this energy transmitted to the products allows a quasi-selection according to their diameter. Two particles expelled by the same wire at the same frequency and the same amplitude will reach different heights according to their size. For example, by doubling the diameter of a particle, its mass is increased by a ratio of eight. Its projection height is greater as well as the time required for its fall on the filter element or sieving 13, this time depending only on the height reached. It can be estimated that a particle projected at 30 mm has a drop time of 0.07s, during which, for example, at 40 kHz, the filtering or sieving element 13 has vibrated 2800 times, making it possible to put a very large number of smaller particles moving. By increasing the frequency of vibrations up to 150 kHz while maintaining the same amplitude, a much larger number of particles are suspended per unit of time while giving smaller particles higher energy due to higher acceleration. transmitted. Increasing the frequency up to 150 kHz significantly increases the flow rate of the filtering or sieving element 13. The particles that are still in motion are less likely to pass through the filtering or sieving element 13. because of potential collisions with other particles and wires. The separation of the particles thus takes place essentially at the moment when the particles resting on the element or screen 13 are set in motion by the vibrations. Therefore, the emission of ultrasonic vibrations to the structure 11 is performed in pulsed mode so that a cycle of rest and vibration is performed. The duration of the rest cycle is determined by the return time of the particle that has been projected the highest above the element 13. This time is of the order of 0.1 to 0.2s depending on the product to be separated, regardless of the frequency. The vibration time will be determined according to the nature of the product, the flow. For example, the vibration time may correspond to approximately three cycles associated with the particle expelled at the greatest distance from the element 13, ie of the order of 0.15 to 0.3s at 40 kHz, this time therefore being adapted according to the frequency.

The filtering or sieving element 13 may adopt a generally flat arrangement inclined relative to the horizontal. The inlet zone 14 is provided near a top edge of the filtering or sieving element 13 and the outlet zone 15 is provided near a low edge of the filtering or sieving element 13, while the flow direction 16 is naturally oriented from the top edge to the bottom edge.

These results can be achieved irrespective of the shape of the separation device 10. It can in particular be of rectangular shape (like the figure 1 ), square, circular, oval or trapezoidal, or any geometric shape that allows to achieve the desired operation.

In the embodiment illustrated in no way limiting, the structure 11 made for example by machining a solid aluminum plate is rigid, consisting of cells 17 distributed so as to maintain the rigidity of the entire device 10 and in particular of the structure 11 and to allow an optimal transmission of ultrasonic vibrations along the structure 11 from the converter 12. It comprises in particular at least three longitudinal bars 18 oriented in the flow direction 16, interconnected along their length. length by a plurality of reinforcements 19. The side bar 20a is arranged at the high edge mentioned above in relation to the entry zone 14. The side bar 20b is arranged at the low edge mentioned above in relation to the 15. The lateral bars 20a, 20b each connect the ends of two bars 18, so as to close the frame of the structure. The distribution of the reinforcements 19 along the bars 18 is function the total dimension of the device 10 so as to maintain rectangular or square cells 17 adapted to the total dimension of the device 10. The cells 17 are symmetrical or asymmetrical according to the dimensions of the device 10.

The reinforcements 19 may be machined in the mass, welded or screwed according to the determined construction. The reinforcing section 19 is for example triangular with the point facing upwards, but it may have any other form constituting an absence of inconvenience to the flow of products passing. The tip of the reinforcement section 19 is positioned in such a way that it never comes into contact with the filtering or sieving element 13.

The section of the outer bars of the structure 11, whether it is the longitudinal bars 18 or the lateral bars 20a and 20b, is determined to obtain an optimal distribution of the ultrasonic vibrations as well as a sufficient surface to carry out the fixing (for example by gluing ) of the filtering or sieving element 13 on the structure 11. This section (see figure 2 ) can be square or rectangular or preferably slightly trapezoidal. The section of the side bar 20b on the outlet zone side 15 may be different to allow a non-planar attachment of the filtering or sieving element 13 to the structure 11. In other words, in the case where the filtering or sieving element 13 is attached to the structure 11 at least at the outlet area 15 on the side bar 20b, the bonding surface 25 at the exit zone 15 between the filtering or sieving element 13 and the structure 11 can be included in a plane different from the plane of the filter element or sieving 13 on the rest of the device 10. The angle formed between the attachment surface 25 (for example by gluing) relative to the plane of the remainder of the filter element or sieving 13 is between 1 to 90 °. This angle can be achieved in the entire width of the side bar 20b or on a part of this one, and consist of one or more sections. The embodiment illustrated on the figure 3 has two 45 ° faces whose edge is offset from the center of the output bar 20b, this edge of the exit zone may be on the same plane as the structure or 0.2 millimeters to a few millimeters in below so as to be on a plane equal to or less than the plane of gluing the plane faces.

In addition, the separation device 10 may comprise an adjustment element (not shown) of the inclination of the filter element or sieve 13 relative to the horizontal in a given range of a few degrees, for example between 0 ° and about 10 ° to adjust the flow rate of the products being separated in the direction 16 as a function of their ability to flow along the filtering or sieving element 13 (shape, weight, nature of the products) . The tilt adjustment element may be constituted by any suitable means, mechanical and / or electrical and / or manual. The flow of the products and the advance of the refusals along the device 10 is done simply by adjusting the slope of the device which will be higher at the input 14 of the products than at the exit 15 refusals. A particle projected orthogonally to a wire falls downstream from its point of departure. A particle projected at an altitude of 30 mm, for example from a sloping filter element at 7 °, will drop about 4 mm downstream of its starting point. The repetition of the flights and falls provides a controlled flow to the exit zone 15 where the rejected particles fall for example into a recovery hopper without any movement or necessary mechanical action, simply under the effect of gravity . The adjustment of the slope is also a function of the flow observations of the products on the filtering or sieving element 13.

With reference to the figure 1 , the electroacoustic converter 12 is connected to the structure 11 at the input zone 14 by means of fixing elements 21. In particular the converter 12, itself powered by a generator not shown by means of a connecting cable 22, can be fixed in the center of the input zone 14 in the lateral direction orthogonal to the direction of However, it can be fixed at any other point of this face without prejudice to operation, which confers an adjustment to obtain the correct resonance frequency. An advantageous solution is to choose fastening elements 21 tuned to the excitation frequency delivered by the converter 12. For example the length and shape of the fastening elements 21 can be chosen in half-wavelength of the frequency of 'excitation. The fastening elements 21 may for example adopt the shape of an extension bar which allows the tuning frequency. The converter 12 or the converter 12 / extension bar assembly 21 is screwed to the structure 11 for example. The vibration frequency is in the field of power ultrasound, ie between about 20 and 150 kHz, for example.

If the filtering or sieving element 13 is bonded to the bars 18, 20a and 20b, this is done using a glue of the smallest possible thickness so that it has no role. in the damping of ultrasonic vibrations and that it does not heat up under the action of ultrasonic vibrations during the transmission of the structure 11 to the filter element or sieving element 13. The adhesive film between the filter element or sieving 13 and the structure 11 is marked 23. The transmission of ultrasonic vibrations to the filtering element or sieving 13 depends in particular on the quality of the glue used and the quality of the uniform tension of the filter element or sifter 13. This The tension must be 20 to 60 kg / cm 2, the reference value being around 40 kg / cm 2 to optimize the efficiency of the converter 12 and allow a homogeneity of the transmission speed of the vibrations in the structure 11 and the filter element or sieving 13 However, it is important not to exceeding the elastic limit of the material constituting the filtering or sieving element 13. Each wire of the filtering or sieving element 13 when constituted by a wire cloth behaves like a tuned vibrating cord, the propagation of the vibrations being effected by a sinusoidal vibration of this wire. This own vibration of the wire subjected to a given frequency is completed by a lateral displacement at the same frequency due to the longitudinal vibration of the structure 11 completed by a longitudinal displacement at the same frequency due to the lateral vibration of the structure 11. These three a number of synchronized and combined movements lead to a perfectly homogeneous vibration of the entire surface of the filtering or sieving element 13. The amplitude of the undulations is controlled by the generator which makes it possible to adjust the electric current delivered to the converter 12. The voltage applied to each wire makes it possible to maintain a constant amplitude over the entire surface of the filtering or sieving element 13. A lowering of the mechanical tension of the filtering or sieving element 13 at the time of bonding, or following degradation, would lead to to an increase in the voltage to be applied to the converter 12 which would confer a This amplitude can not be transmitted in its entirety to the filtering or sieving element 13 because of its insufficient tension, a part of the energy delivered would be transformed into heat transmitted in the joints of the structure. In addition, the stresses imposed on the structure 11 would be greater, which could lead to its deterioration.

The provision of such a product separation device 10 has the advantage of being able to construct an apparatus or a machine comprising at least one such separation device 10 mounted integral with a rigid chassis by connecting elements (not shown), the apparatus also comprising a feed device for discharging products to be separated on the filtering or sieving element 13 of the filtering device. separation 10, especially at the input zone 14. It becomes advantageous to provide that the apparatus comprises several separation devices 10 configured and superimposed on top of each other so as to have decreasing retention gauges in going from top to bottom. In such a construction, the uppermost device 10 is directly powered by the feeder. For the devices 10 other than the one above, the products to separate feeding a given separation device 10 consists of the passers of the separating device 10 directly above. Each of the stages of the apparatus is therefore constituted by a separate separation device 10 which operates as described above. The major advantage lies in the possibility of superimposing the devices 10 with calibrated granulometry to make successive cuts without grouping the products or having to distribute them on each floor. The separation is done by stacking the devices 10 separated by the rigid chassis by putting the filter element of smaller size to the lower stage and the gauges being larger and larger from bottom to top. This device also makes it possible to adapt the size of the filtering or sieving elements to the relative flow rate that it must separate. For example, a machine is fed at 100 kg per hour, the quantity of products arriving on the fourth lower device is only 5 kg per hour, it requires only a filter surface 50% smaller, the realization allows and to make a significant saving of filter element or sieving whose cost increases sharply when the retention size decreases from 25 microns.

The feed device may be configured to ensure a spill of the products over the entire width of the filtering element or sieve 13 of the device above the most, in particular in the form of a curtain of products of constant thickness. The spill may include, but is not limited to, continuous operation.

The connecting elements between the separation device (s) 10 and the rigid chassis of the apparatus comprise at least one seal interposed between the structure 11 and a contact surface of the rigid frame intended to support the structure 11. The seal is in particular integral with the structure 11 of the separation device 10, for example by gluing thereof, and its production is neat, which eliminates any friction and heating between the structure 11 and the seal while it gradually absorbs ultrasonic vibrations. It may be an elastomeric foam provided for this purpose. The seal is spotted 24 on Figures 2 and 3 . The contact surface of the frame that receives the device 10 may also be equipped with a seal of the same nature as the seal 24 secured to the device 10, for example glued on a metal flange. In case of presence of two joints, these are selected for a great coefficient of friction at the interface between the two joints: there is drive of the movements of the joints of the rigid chassis (which is a structure obtained by boilermaking for example) by the seals 24 of the structure 11 without relative displacement. The final damping of the vibrations takes place before they reach the rigid chassis which, on the contrary, remains safe from any vibration and any heating.

The connecting elements between the separation device (s) 10 and the rigid chassis of the apparatus also comprise at least one clamping member, in particular at least one compression spring, this member being configured to tighten the clamping device. separating against the contact surface of the rigid frame by compressing the seal (s) in a manner limiting or even preventing the transmission of ultrasonic vibrations to the rigid frame. Tightening with the aid of springs makes it possible to obtain a controlled and identical pressure over the entire surface of the seal 24. This pressure is calculated to allow the absence of product leakage to the outside or between the various stages of the seal. 'apparatus. Since each of the devices 10 is not animated by any movement and that the seal 24 is bonded to the structure 11 thereof, the clamping pressure can be minimized to maintain the seal without compressing the seals completely, which would change their behavior to the transmission of ultrasonic vibrations. Unsuitable seal quality or improper tightening may result in either product leakage or vibration transmission to the rigid frame as well as severe heating of the seals 24 and all or part of the device 10 in a noisy environment. harmonic frequencies developed.

The apparatus may advantageously comprise an element for containing the discharged refusals out of the filtering or sieving element 13 at the end of the separation. The flow 16 of the rejected products constituting the refusals is contained for example by elongations screwed to the device (s) 10 in a sealed manner, these extensions being made of nylon® or Delrin® or any other material absorbing the ultrasonic vibrations without warming up. The fixing of these extensions is carried out for example by nylon screws which do not transmit any vibration.

In the case where the apparatus comprises at least one separating device 10 with an input zone 14 and an output zone 15 at different altitudes, the step of separating the products (which results solely from ultrasonic vibrations of the element filtering or sieving 13 induced by the vibration of the structure 11 by the electroacoustic converter 12) is effected by flowing 16 of the products to be separated along its filtering or sieving element 13, with a dispersion of the constituents of passers-by passing through the filtering or sieving element 13 as a function of a gradation gradient increasing in the direction of flow 16.

Indeed, for the products distributed at the inlet 14 of the device of the largest retention caliber placed at the top, the thinnest of these pass through its filter element or sieving 13 from the first millimeters when the flow 16. Then gradually, it is increasingly larger products that flow and pass through the filter element or sifter 13. At the exit zone 15 pass through the element 13 only passers who have dimensions very close to the retention size of the filter element or sieve 13. The passers-by recovered under the first device 10 are thus summarily classified and the passers-by recovered under the second and third third contain only very few powders smaller than the retention gauge of the second device 10 directly below, so it is not necessary that they traverse the entire length of the second device 10. This This pre-selection allows a dispersion of loops on the lower device as a function of a grain size gradient. On the contrary, only the thinnest loops (ie those passing through the first part of the first upper device) require an intense separation operation on the second lower device. This pre-selection makes it possible to reduce the quantity of particles present at the inlet of the apparatus, they are not congested by the presence of large particles which require only a very brief separation operation. This feature makes it possible to adjust the length necessary for separation to the product population: the smaller the products are compared to the retention size of the filtering or sieving element 13 of the upper device 10, the more they fall upstream of the element filtering or sieving 13 of the lower device 10 and are exposed to an intensification of the separation operation, due to the concomitant increase in the duration of the flow 16. This rain distribution over the entire surface of the lower device decreases. the layer thickness effect, increases the effectiveness of ultrasonic vibrations on the lower device and limits collisions between the particles.

Finally, the separation step may advantageously comprise an adjustment of the flow length 16 of the products to be separated as a function of a desired upper threshold of granulometry of the loops. Indeed, the apparatus is static and it is thus possible to determine perfectly what flow length 16 and therefore what length of filter element or sieving 13 is necessary to achieve the perfect granulometric limit passersby. To do this, it suffices to introduce from the exit zone 15, for example, a receiving plate which makes it possible to collect passers-by just below the lower device and to analyze their particle size zone by zone. If the filter element or sieving 13 has a retention size too large compared to the desired product, simply hide the downstream part which corresponds to the area where appear passers too big or too many. It is therefore possible to adapt a device to the product without having to replace its filtering or sieving element 13. In the same way, it is possible to limit the proportion of particles whose shape is too far from the average particle shape. having an ovoid shape instead of spherical coming to separate from other particles and group mainly in the downstream part of the filter element or sieving 13.

The apparatus thus described is compact, quiet, perfectly adaptable to the desired product and without any internal product retention zone. The settings are few: the slope of the device 10, the amplitude of the ultrasonic vibrations, the duration of the on and off times of the ultrasonic vibrations.

• le dispositif de séparation ou l'appareil est une machine sans mouvement qui permet un taux d'extraction élevé reproductible qui n'utilise que l'énergie des ultrasons,
• le silence de fonctionnement découle du point ci-dessus,
• l'absence de mouvement permet d'avoir des joints qui ne reçoivent qu'un serrage très faible et donc qui ne sont pas affectés par les vibrations très énergétiques des ultrasons tout en assurant l'absence totale de fuite et une parfaite adaptabilité des éléments 13, ceci permettant aussi le collage des joints qui est une étape décisive,
• le fonctionnement est stable et reproductible grâce à une alimentation préalablement organisée pour se faire selon un rideau contrôlé et adapté au débit acceptable par la première surface filtrante ou tamisante,
• absence de rétention de produits à l'intérieur de l'appareil.

It follows from the foregoing advantages and functions:

• the separation device or the apparatus is a machine without movement which allows a reproducible high extraction rate which uses only the energy of the ultrasounds,
• the silence of operation stems from the point above,
• the absence of movement makes it possible to have seals which receive only a very weak tightening and thus which are not affected by the highly energetic vibrations of the ultrasounds while ensuring the complete absence of leakage and a perfect adaptability of the elements 13 , this also allowing the bonding of the joints which is a decisive step,
• the operation is stable and reproducible thanks to a feed previously organized to be done in a curtain controlled and adapted to the flow rate acceptable by the first filtering surface or sieving,
• lack of retention of products inside the device.

Claims (18)

1. Device (10) for separating products comprising a structure (11) made to vibrate by an electro-acoustic converter (12) and supporting a filtering or screening element (13), characterized in that the assembly is configured such that the separation of products into fines through the filtering or screening element and waste results only from ultrasonic vibrations of the filtering or screening element induced by the vibrating of the structure by the electro-acoustic converter.
2. Device for separating products according to Claim 1, characterized in that the assembly is configured such that the discharging of the waste out of the filtering or screening element results only from the effect of gravity to allow a separation of the products and a discharging of the waste that are continuous with no internal retention of products.
3. Device for separating products according to one of Claims 1 and 2, characterized in that it comprises an input zone (14) intended to be supplied with products to be separated, the prior spreading of which allows for the supply as a continuous curtain over its entire width, and an output zone (15) for the waste after separation, and in that it is configured such that the filtering or screening element, under the effect of the ultrasonic vibrations transmitted by the structure, generates a flow (16) of the products currently being separated from the input zone to the output zone by allowing the fines to pass through the filtering or screening element during this flow.
4. Device for separating products according to Claim 3, characterized in that the input zone (14) is situated at a height greater than that of the output zone (15).
5. Device for separating products according to one of Claims 3 and 4, characterized in that the filtering or screening element is globally flat and inclined relative to the horizontal and in that the input zone is provided in proximity to a high edge (20a) of the filtering or screening element and the output zone is provided in proximity to a low edge (20b) of the filtering or screening element, the direction of flow (16) being oriented from the high edge to the low edge.
6. Device for separating products according to Claim 5, characterized in that it comprises an element for adjusting the inclination of the filtering or screening element within a given range of a few degrees, for example between 0° and approximately 10°, to adjust the rate of flow of the products being separated as a function of their flow capacity.
7. Device for separating products according to one of Claims 5 and 6, characterized in that, the filtering or screening element being fixed to the structure at least at the level of the output zone, the fining surface at the output level between the filtering or screening element and the structure is contained in a plane different from the plane of the filtering or screening element, the edge of the output zone being able to be on a plane equal to or lower than the fining plane of the flat faces.
8. Device for separating products according to one of Claims 1 to 7, characterized in that the emission of the ultrasonic vibrations to the structure is performed in pulsed mode.
9. Device for separating products according to one of Claims 3 to 8, characterized in that the electro-acoustic converter is coupled to the structure at the level of the input zone using fixing elements (21) .
10. Apparatus comprising at least one device (10) for separating products according to any one of Claims 1 to 9, secured to a rigid frame by link elements, the apparatus comprising a feed device for pouring products to be separated onto the filtering or screening element (13) of the separation device.
11. Apparatus according to the preceding claim, characterized in that the link elements between the separation device and the rigid frame comprise at least one seal (24), notably secured to the structure (11) of the separation device, interposed between the structure (11) and a contact surface of the rigid frame, and configured so as to absorb the ultrasonic vibrations of the structure without heating up.
12. Apparatus according to the preceding claim, characterized in that the link elements between the separation device and the rigid frame comprise at least one clamping member, notably a compression spring, configured to clamp the separation device (10) against the contact surface of the rigid frame by compressing the seal (24) in a way that limits or even avoids the transmission of ultrasonic vibrations to the rigid frame.
13. Apparatus according to one of Claims 10 to 12, characterized in that the feed device ensures a pouring of the products over the entire width of the filtering or screening element, notably in the form of a curtain of products of constant thickness.
14. Apparatus according to one of Claims 10 to 13, characterized in that it comprises an element for containing the waste discharged from the filtering or screening element.
15. Apparatus according to one of Claims 10 to 14, characterized in that it comprises a number of separation devices (10) configured and superposed one on top of the other so as to offer retention gauges decreasing from top to bottom, the products to be separated feeding a given separation device other than the topmost one consisting of the fines from the separation device directly above.
16. Method for separating products using an apparatus according to any one of Claims 10 to 15, comprising a step of separation of the products into fines through the filtering or screening element and waste, characterized in that the separation results only from ultrasonic vibrations of the filtering element induced by the vibrating of the structure by the electro-acoustic converter.
17. Method for separating products according to Claim 16, comprising at least one separation device according to one of Claims 3 to 9, characterized in that the step of separation of the products is done by the flow (16) of the products to be separated along the filtering or screening element of said filtration device, with a dispersion of the products constituting the fines passing through the filtering or screening element as a function of a particle size gradient increasing in the direction of flow.
18. Separation method according to Claim 17, characterized in that it comprises an adjustment of the length of flow of the products to be separated as a function of a desired upper threshold of particle size of the fines.

Images