MXPA99005798A - Device for dynamic separation of two zones - Google Patents

Abstract

To ensure the dynamic separation of at least two zones (10a, 10b) between which objects or products are to be transferred at high speed, without any break of confinement, these zones (10a, 10b) are connected by at least a buffer zone (12) forming a dynamic screen. A dynamic confinement system (14a, 14b), set between each pair adjacent communicating zones (10a, 12, 10b) forms therein an air curtain (16a, 16b), with two or three clean air jets. The buffer zone (12) comprises a blowing ceiling (18) and, optionally, a suction vent facing it.

Description

DEVICE FOR DYNAMIC SEPARATION OF TWO ZONES Technique The invention relates to a device used to dynamically separate at least two zones in which there are different environments, to allow objects or products to be transferred from one area to another, to a high speed, they are breaking in confinement. The process according to the invention can be used in many industrial sectors. So, this process applies to all industries (food processors, medical industry, biotechnology, high technology, nuclear, chemical, etc.) in which different environments have to be maintained in areas communicated with each other to allow the frequent passage of objects and products. The term "environment" refers particularly to aeraulic, gaseous conditions and especially to concentrations, relative humidity temperature, etc. The most recent in the art Currently, there are two types of solutions for the dynamic separation of two areas communicated with each other, for example with the aim of allowing objects to pass from one side to another; These two types are protection by ventilation and protection by air curtain. Ventilation protection consists of artificially creating a pressure difference between two zones in such a way that the pressure in the area to be protected is greater than the pressure inside the contaminated zone. In this way, if the area to be protected contains a product that could be contaminated by the ambient air, the laminar flow is injected into the area to be protected which blows out through the access opening in the direction of this separation zone. In the opposite case where it is necessary to protect personnel and the environment outside a contaminated space, dynamic confinement is achieved through the use of exhaust ventilation in this contaminated space. In each case, an empirical standard imposes a minimum ventilated air velocity of 0.5 m / s in the plane of an opening through which the two zones communicate, with the aim of preventing the contamination from being transferred to the area that is going to protect. However, the efficiency of this ventilation protection technique is not perfect, particularly in what is called "infractions" situations, in other words when the objects are transferred between the two zones. In addition, this type of protection makes it necessary to process and control the entire area to be protected from the entry of contaminated external air or the entire contaminated area. When the area to be protected and controlled is very broad, this leads to a particularly high investment and production costs. Finally, this ventilation protection technique only provides protection in one direction, in other words it is useful only when the transfer is possible only in one direction. The air curtain protection technique consists of injecting, simultaneously, one or several adjacent clean air jets, in the same direction in a separation zone between the two zones, which forms an immaterial door between the area that is going to protect and the contaminated area. It should be noted that, according to the theory of turbulence plane jets, the flat air jet is composed of two separate zones; a transition zone (or central zone) and a development zone. The transition zone corresponds to a central part of the jet near the nozzle in which the clean air is injected. Within this zone, in which there is no mixing between the injected air and the air on the other side of the jet, the velocity vector is constant. Considering a cross section through the plane perpendicular to the plane of the separation zone, the width of the transition zone is gradually reduced as the distance from the nozzle increases. This is the reason why this transition zone is called "language" in our text. The zone of development of the jet is the part of this jet that is located outside the transition zone. In this area of development of the jet, the outside air enters by means of the flow of the jet. This results in variations in the velocity vector and the air mixture. The entry of air into both surfaces of the jet within this zone of development is called "induction". Thus, the jet of air induces a flow of air in each of its surfaces, which depends particularly on the injection flow of the jet considered. Documents FR-A-2 530 163 and FR-A-2 652 520 propose an air curtain to separate the contaminated area from a clean area. In both cases, the air curtain consists of two adjacent clean air jets that blow in the same direction. More precisely, the dynamic separation is provided by a relatively slow first jet (called "slow jet"), for which the tongue covers the entire entrance. The second jet (called "fast jet") is faster than the slow jet and is installed between the slow jet and the area. Its function is to stabilize the slow jet by means of a suction effect that puts this slow jet in contact with the fast jet. In these documents, it is specified that the tongue of the slow jet is sufficiently long to cover any opening when the width of the injection nozzle of the slow jet is equal, at least 1/6 ° of the height of the opening that is going to to protect.

Document FR-A-2 652 520 also proposes the simultaneous injection of clean air at a temperature adapted to the requirements, within the clean area to be protected. It should be noted that this clean ventilation air should be injected at an average approximately equal to the average induced by the surface of the rapid jet that is in contact with the clean ventilation air. Furthermore, document FR-A-2 659 782 proposes adding a third jet of clean, relatively slow air to the second clean air jet used in documents FR-A-2 530 163 and FR-A-2 652 520 so that the fast jet is placed between the two adjacent slow jets in the same direction. Thus, the flow of clean ventilation air injected into the area to be protected is considerably reduced due to the fact that the induction in this zone occurs through the development zone of one of the slow jets, more than by the zone of development of the rapid jet in the case of an air curtain with two jets. In addition, dynamic confinement is provided in both directions, which was not the case in what it describes in the aforementioned documents. WO-A-96 24011 also describes an installation in which the chamber contains a confined atmosphere, communicated with the same atmosphere outside through one or two openings, with which the curtain is associated. Each curtain is formed of a slow jet supported by a rapid jet as described in documents FR-A-2 530 163 and FR-A-2 652 520. The camera can be used for the continuous processing of products due to injection of a reagent within it. The products pass from the outer atmosphere into the confined atmosphere in this chamber so that it is processed in it before it leaves for the outer atmosphere again. 'In spite of the improvements made to the air curtain technique described in these documents, the problem of transferring objects or products to a high average between the two zones in which there are different environments without breaking the confinement has not yet it is satisfactorily solved by the device that is known, particularly if there is a risk of an exchange of contamination between the two zones. Description of the Invention More particularly, the purpose of the invention is a device for the dynamic separation of at least two zones in which there are different environments between which a rapid transfer of objects or products must be made, without breaking the confinement , even in the case in which there is a risk of exchange of contamination between the two zones.

According to the invention, this result is obtained by means of a dynamic separation device in at least two zones in which there are different environments, characterized in that it comprises: - at least one buffer zone with a used controlled atmosphere for communication between the two zones that are to be separated; the means for dynamic confinement placed between each pair of adjacent communicated zones to create an air curtain between these zones comprising a first relatively slow clean air jet comprising a tongue that completely closes the communication between the zones, and a second jet of relatively fast clean air in the same direction as the first jet and adjacent to it, on the side of the buffer zone. The term "controlled atmosphere" refers to the fact that all the characteristics of the air present in the buffer zone, such as temperature, relative humidity, air conditions, gases and particular concentrations, etc., are controlled. The expression "communicated, adjacent zones" refers to each group of two zones in the set formed by the zones to be separated and by the buffer zones, which communicate directly with each other. In this way, in the case in which the device comprises a single buffer zone located between the two zones to be separated, there are two pairs of adjacent communicating zones formed by a single buffer zone and one of the zones to be separated. When there are several buffer zones, there are at least one pair of adjacent, communicated zones formed of two buffer zones. The arrangement consists of one of several buffer zones between the areas to be separated, and air curtains formed, at least from two jets of clean air between the adjacent communication zones, which allows products or objects to be transferred to high speed while preventing contaminants present in any of the controlled areas from reaching the other controlled environment zone, and vice versa. Each buffer zone acts as a dynamic closure between the zones to be separated. Preferably, the means for dynamic confinement that is inserted between each pair of adjacent communicated zones are such that the second (rapid) jet in each air curtain is injected at a flow such that the air flow induced by the surface of the second jet in contact with the first jet (slow) is less and is preferred, approximately equal to half the first injection average.In a special embodiment, these means for dynamic confinement are such that the air curtain comprises a relatively slow third jet in the same direction as the first and second jets and adjacent to the second (fast) jet on the same side of the jet. buffer zone. Thus, this third jet comprises a tongue that completely closes the communication between the zones and is injected at a flow significantly equal to the injection flow in the first jet, so that the air flows induced by the surfaces of the second jet in contact with the first and third jets, respectively, are smaller than, or preferably approximately equal to, one half of the jet injection flows. In practice, each of the dynamic confinement means comprises at least two adjacent air supply nozzles and an inlet grid which is directed towards the supply nozzles and is placed in a plane parallel thereto. The air supply nozzles and the inlet grids are placed in line with the upper and lower surfaces of the buffer zone. In order to improve the behavior of the device, particularly in situations of infringement through the air curtains, preferably the buffer zone comprises a ventilation, such as a ceiling fan, associated with injection means that inject air clean towards this area. Then, the flow from these injection means is at least equal to the sum of the air flows induced by each of the surfaces of the jets in the air curtains in contact with the buffer zone. Furthermore, the flow of the injection means is such that it provides a minimum velocity of 0.1 m / s through the areas of the planes at the ends of the buffer zone. In this case, the buffer zone may also comprise an inlet grid distributed over the entire lower surface. Then, the flow from the injection means is equal, at least to the sum of the air flow directed by the intake grid and the air flow induced by each of the surfaces of the jets of the air curtain in contact with the buffer zone. In addition, the flow from the injection means should always be sufficient to provide a minimum velocity of 0.1 m / s across the area of the planes at the ends of the buffer zone. This arrangement corresponds, in particular, to the case in which the buffer zone is used to carry out an elementary operation (distribution, packaging, etc.) of the objects or products transferred between the zones to be separated. In the latter case, several buffer zones can be placed in series between the zones to be separated. The air curtains inserted between the two buffer zones are delimited by the internal walls with a width equal to the width of the nozzles for the adjacent air supply. In addition, in relation to the number of buffer zones used in the device, the air curtains inserted between the buffer zone and one of the areas to be separated are delimited by the internal walls with an equal width, at least at the maximum thickness of the air curtains. BRIEF DESCRIPTION OF THE DRAWINGS Some examples will now be described, without intending to limit the invention, of the different embodiments of the invention with reference to the accompanying drawings in which: FIG. 1 is a perspective view illustrating in FIG. diagram the use of a single buffer zone to provide communication between two zones with controlled environments through two air curtains in which each is formed of two adjacent clean air jets according to the first embodiment of the invention; Figure 2 is a perspective view comparable to Figure 1 illustrating the case in which each air curtain is formed of three adjacent clean air jets according to the second embodiment of the invention; and Figure 3 is a perspective view diagrammatically illustrating the use of several buffer zones in series between the two zones with controlled environments, with the insertion of an air curtain between each pair of adjacent communication zones. DETAILED DESCRIPTION OF TWO EMBODIMENTS The area to be protected and the contaminated area are marked with references 10 and 12 respectively in Figure 1. In the embodiment shown, the area to be protected 10 is It consists of a specific clean space for the work station and the contaminated area 12 includes everything outside this station. This external space forms a source of thermal, particulate, gaseous and / or microbial contamination of the specific space for the work station. The work station that forms the area to be protected 10, is delimited by walls in all directions, except to the right, as shown in Figure 1, More precisely, the surface of the work station that is oriented towards right in figure 1, it forms a separation zone consisting of an opening 11, through which the protection zone to be protected 10 communicates with the contaminated external zone 12. This opening 11 can be used, for example, to allow the taking of objects inside and outside the area to be protected 10, and for handling, when necessary, within this area, from outside the contaminated area 12. Note that this illustration is simply of an exemplary embodiment and is in no way limiting in nature, since zones 10 and 12 can communicate with one another through one or more separation zones with arbitrary orientations that do not necessarily materialize in the openings. without leaving the objective or framework of the invention. In particular, in an embodiment that is not shown, the area to be protected is a conveyor belt that moves along a linear, circular or widthwise path, and the separation zone, between the contaminated zone and the area to be protected extends longitudinally along the path of the conveyor belt. In order to preserve the dynamic separation between zones 10 and 12 despite the presence of opening 11, a permanent air curtain 14 is formed in this opening when the installation is used. In the embodiment shown, by means of a diagram, in Figure 1, this air curtain 14 is formed by injecting two adjacent, clean air jets simultaneously in the same direction. More precisely, the first clean, relatively slow air jet is injected into the opening 11 (of which only the tongue 16 is shown) and in the second jet of clean air is also injected into the opening 11, which is relatively quick compared with the first jet (of which only the tongue is shown). The second jet is injected between the first jet and the area to be protected 10. To simplify, in the rest of the text, the first and second jets are called "slow jet" and "fast jet" respectively. The jet is injected into the opening 11 by means of adjacent nozzles 20 and 22. In the embodiment shown, the opening is rectangular and comprises two horizontal edges and two vertical edges (and in a manner that is not considered to be limiting). ), the injection nozzles 20 and 22 extend along the entire length of the upper edge of the opening 11 such that the air curtain 14 is formed over the full width of the opening 11. Then, the two jets forming the air curtain 14 are completely recovered through a single inlet 24 which extend along the lower edge of the opening and over the entire length of this edge.The vertical edges of the opening 11 materialize by io of the two walls 26 located on either side of the two jets forming the air curtain 14. These two side walls 26 extend into the contaminated zone 12 at a distance at least equal to the maximum thickness of the jets. As shown in the diagram of figure 1, the slow jet injected through the nozzle 10 has a size such that the tongue 16 covers the entire plane of the opening 11 to be protected. This result is obtained by the taking steps to ensure that the range, or length of the tongue 16 is, at least, equal to the height of the opening 11. Accordingly, the width of the nozzle 20, parallel to the plane of the Figure 1 is at least equal to 1/6 and preferably 1/5 of the height of the opening 11 to be protected. Thus, and only as an example, the width of the nozzle 20 will be at least 0.20 m for an opening of 1 meter high. Furthermore, in order to minimize turbulence as well as for economic reasons, the velocity of the slow jet exit from the nozzle 20 is set at 0.5 m / s. Since the length of the tongue 16 of the slow jet is at least equal to the height of the opening to be protected and this jet is relatively slow, the flow of air jets around the objects passing through the air curtain 14 without breaking the confinement.

However, the low speed of the slow jet injected by the nozzle 20 results in the jet, if used alone, being destabilized by the mechanical or air alterations that may occur near the air curtain, so that breaks the confinement of the work station. This is the reason why the fast jet injected by means of the nozzle 22 is injected near the slow jet, at a higher speed in order to stabilize the first jet and consequently improve the efficiency of the confinement in situations of infringement through of the dynamic barrier formed by the air curtain 14. As an example, which is not intended to limit the invention, the width or width of the nozzle 22, through which the jet is injected, may be less equal 1/40 the width of the nozzle 20, which is equal to 0.005 m in the example described. In order to optimize the barrier effect provided by the combination of the two jets, the applicants have determined that the injection flow of the jet stream, injected through the nozzle 22, must be adjusted in such a way that the air flow induced by the surface of this rapid jet, which is in contact with the slow jet injected through the nozzle 20, is smaller than, or preferably, approximately equal to half the injection flow of this slow jet. Experiments and simulations have shown that these characteristics significantly improve the barrier effect compared to the prior art, in that the flow of the fast jet is adjusted in such a way that the air flow induced by the surface of this rapid jet, in contact with the slow jet, it is approximately equal to the injection flow of the slow jet. As an example, which is not intended to limit the invention, if the puff flow of the slow jet injected through the nozzle 22 is 360 m3 / h, the puff flow of the rapid jet injected through the nozzle 22 it should be approximately 42 m3 / h. This value should be compared with the value of approximately 84 m3 / recommended in the prior art. In order to recover all the air that is blown through the nozzles 20 and 22, as well as the air that enters through the air curtain 14, the inlet 24 communicates with a suction means (not shown). ) with an appropriate size for this purpose. In practice, the air recovered from the inlet 24 is cleaned by means of a special cleaning mechanism (not shown) before it is recycled to the injection nozzles 20 and 22. Then, the excess air is released towards the outside after a second special cleaning.

In the numerical example given above, the flow of air sucked through inlet 24 is 825 m3 / h. Applicants have also determined that the effect of the barrier is further optimized when each of the two jets is injected along a direction approximately parallel to the vertical plane of the opening 11, and when the inlet 24 is perpendicular to this direction. In other words, it is desired that the outlet holes from the nozzles 20 and 22 be located in the same horizontal plane and that the inlet 24 should be placed below the nozzles 20 and 22 in another horizontal plane. In addition, the purifying effect of the area to be protected 10 is obtained by providing internal ventilation in this area and respecting the injection flow defined for this internal ventilation. This purification effect added to the barrier effect provided by the air curtain 14, significantly improves the efficiency of the confinement, particularly in infringement situations. More especially, in the embodiment shown in FIG. 1, which is related to the air curtain 14 composed of two adjacent jets in the same direction, the clean, injection air flow within the area that is will protect 10 is equal to the air flow induced by the rapid jet injected through the nozzle 22, on the surface of this rapid jet, which is in contact with the clean ventilation air, in other words on the surface of the rapid jet that is oriented towards the area to be protected 10. In addition, the clean ventilation air is it injects at a speed such that the velocity of this air divided by the area of the plane of the opening 11 is at least equal to 0.1 m / s. In the illustrated embodiment, by means of a diagram, in Figure 1, the clean ventilation air is injected into the area to be protected 10 through a blow inlet grate 28 which extends through the entire rear wall of the area to be protected, in other words, on the entire wall of the working area which faces the opening 11 and lies parallel to the vertical plane of this opening. The intake grid 28 through which the clean ventilation air is injected, is located on the left side of Figure 1. In the aforementioned embodiment (not shown) according to which, the area that is to be protected is a conveyor belt that moves along a given path, the wall, in which the clean ventilation air forms the injected purifying flow, is on the upper surface of the area to be protected. This surface is oriented towards the conveyor and is then approximately perpendicular to the plane of the separation zone. When the temperature within the area to be protected 10 is to be maintained at a uniform value, the clean ventilation air is injected through the inlet grate 28 at a regulated temperature. Accordingly, the means for temperature regulation as a heat exchanger, (not shown) is placed in the ventilation circuit on the upstream side of the intake grid of the blower 28. In the example, which has no The intension of limiting, which was mentioned above, the puff flow for internal ventilation is 360 m3 / h. Experiments and simulations have shown that, if the characteristics described above are respected, the efficiencies of the confinement is 10 to 100 times greater than the possible efficiency obtained with the prior art. In this way, with the characteristics described above, the efficiency of the confinement of a dynamic barrier defined as the average of the concentration of particulate or gaseous pollutants, in the contaminated zone, in relation to the concentration of the same pollutants in the area that is. will protect, can reach values between 104 and 105.

Figure 2 shows a second embodiment of the process according to the invention. This second embodiment uses the same main characteristics described above with reference to Figure 1, and also shows the third relatively slow jet between the fast jet and the area to be protected. This is the reason why the installation elements illustrated in Figure 2 are the same as the elements in the installation described above with reference to Figure 1, so the same reference numbers are used and will not be described in detail . Thus, figure 2 shows the area to be protected 10, the contaminated zone 12, the opening 11, the nozzles 20 and 22 through which the slow jet and the fast jet are injected, respectively, the respective languages that illustrated as number 16 and 18, the side walls 26 of the opening 11 and the intake grid for the blow 218 provide internal ventilation of the area to be protected 10. The air curtain, in this case, indicated by Reference 14 'also comprises a third jet of clean air, relatively slow with respect to the rapid jet, which exits through the nozzle 30 adjacent to the nozzle 22 between the fast jet and the area to be protected 10, shape that is adjacent to the fast jet and in the same direction as the other jets. The tongue of this third jet is illustrated as 32 in Figure 2. The dimensions of the nozzle 30 are selected such that the tongue 32 of the third jet covers the entire opening. Accordingly, the nozzle 30 extends over the entire length of the upper edge of the opening 11, like the nozzles 20 and 22, and the width of these nozzles 30 is at least 1/6 and preferably 1/5 of the height of the opening 11. In practice, the widths of the nozzles 20 and 30 are the same, for example 0.20 m, in the case of the given numerical illustration, without limitation, with reference to Figure 1. In the second embodiment of the process according to the invention, the injection flow of the slow jet exiting through the nozzle 30 is adjusted such that this flow is approximately equal to the slow jet injection flow that exits through the the nozzle 20. Thus, the air flows induced by the surfaces of the rapid jet, which exits through the nozzle 22, in contact with each of the slow jets, are less or preferably equal to one-half of the injection flows. of these slow jets. As illustrated in Figure 2, it is noted that the width of the entrance grid, in this case indicated with the reference 24 ', adapts to the width of the air curtain so that all the jets can be recovered through the entry grid 24 '. More precisely, the entrance grid 24 'for the air curtain 14' formed by three jets, is wider than the entrance grid 24 of the air curtain 14 formed by two jets. The use of an air curtain 14 'formed by three adjacent jets in the same direction provides an efficient dynamic separation of the two zones in both directions. Furthermore, in the second embodiment illustrated in FIG. 2, the presence of another slow jet between the fast jet and the area to be protected 10, can reduce the injection flow of the internal ventilation compared with the first embodiment. The clean ventilation air injection flow through the intake grid of the blower 28 is equal to half the air flow induced by the slow jet emitted through the nozzle 30 at the surface of this third jet that is in contact with clean air ventilation. In the numerical example given above, the injection flow from each of the slow jets is 360 m3 / h, the flow of the blower from the internal ventilation is 360 m3 / h, and the suction flow in the inlet grid 24 'is 1185 m3 / h.

As in the first embodiment of the invention, the three jets are injected, preferably in directions parallel to the plane of the opening 11 and the inlet grid is placed below the injection nozzles 20, 22 and 30, and is perpendicular to this plane. In addition, the speed at which the ventilation air is injected into the area to be protected 10 is advantageously equal to 0.1 m / s. The efficiencies of the confinement obtained in the second embodiment of the invention, illustrated in Figure 2, are similar to the confinement efficiencies given in the case of the first embodiment described above with reference to Figure 1. It should be noted that many modifications can be made to the described installations, are to depart from the objective or framework of the invention. These modifications are primarily related to applications, which are many and are related in all cases where it is necessary to make a thermal and dynamic separation between two environments with different concentrations of gases, particles and / or bacteria (a clean environment and another contaminated environment, and possibly at different temperatures), while allowing objects to pass from one area to another without contaminating the clean area. The examples of these applications are to protect work stations for the processing of foods, medicines, biotechnologies or high technology, presenters for the distribution of sensitive products, etc. Possible modifications are also related to the shape, orientation and number of separation zones through which the two zones communicate and the selection of the edges of the separation zone in the injection nozzles and the location of the grid. entry, which may be different from the presentation described above.

Claims (13)

1. CLAIMS 1. A device for dynamically separating at least two zones in which there are different environments, characterized in that it comprises: at least one buffer zone with controlled atmosphere used for communication between the zones to be separated; the means for the dynamic confinement inserted between each pair of adjacent communicated zones to create an air curtain between these zones comprising a first jet of clean, relatively slow air having a tongue which completely closes the communication between the zones and a second Clean air jet relatively fast in the same direction as the first jet and adjacent to it, on the side of the buffer zone. The device according to claim 1, wherein the dynamic confinement means is such that the second jet is injected into each air curtain at a flow such that the air flow induced by the surface of the second jet in contact with the first jet is not greater than about half the first jet stream. The device according to claim 2, wherein the means for dynamic confinement is such that the second jet is injected into each air curtain at a flow such that the air flow induced by the surface of the second jet in contact with the first jet it is approximately equal to half the first jet of the injection flow. The device according to any one of claims 1 to 3, wherein the means for dynamic confinement are such that each air curtain comprises a third relatively slow air jet in the same direction as the first and second jets and adjacent to the second jet on the same side as the buffer zone, the third jet comprises a tongue that completely closes the communication between the zones and is injected at a flow significantly equal to the injection flow of the first jet, such that the air fluxes induced by the surfaces in the second jet in contact with the first and third jets respectively are less than, preferably approximately equal to one half of the jets injection flows. The device according to claim 4, wherein the means for dynamic confinement are such that the air flows induced in each air curtain by the surfaces of the second jet in contact with the first jet and with the third jet respectively , they are approximately equal to half the injection streams of the first and third jets. 6. The device according to any of the preceding claims, wherein the means for dynamic confinement comprises at least two air supply nozzles, adjacent and a grid for the air intake that are directed towards each other and are located in two parallel planes. The device according to claim 6, wherein the supply nozzles and the inlet grids are located in line with the upper surface and the lower surface of the buffer zone. The device according to any one of the preceding claims, wherein the buffer zone comprises the ventilation associated with the injection means, the outlet of the clean air towards the buffer zone at an equal flow, at least half of the sum of the air flows induced by each of the surfaces of the jets of the air curtain in contact with the buffer zone, the injection flows are such that they create a minimum speed of 0.1 m / s across the zones of the planes at the ends of the buffer zone. The device according to claim 8, wherein the ventilation comprises a fan in the ceiling. 10. The device according to any of claims 8 and 9, the buffer zone comprises an input grid distributed over the entire lower surface, the flow of the injection means is equal, at least to the sum of the air flow in the intake grid and the air flow induced by each of the surfaces of the jets of the air curtain in contact with the area of cushioning. The device according to any of the preceding claims, in which several buffer zones consist of side walls that are placed in series between the areas to be separated, the air curtains inserted between the two buffer zones are delimited by the continuity of the side walls and the air curtains inserted between the buffer zone and one of the areas to be separated are extended by the walls with an amplitude, at least, equal to the maximum thickness of these air curtains. The device according to any one of claims 1 to 10, wherein a single buffer zone composed of the two walls is inserted between the areas to be separated, the air curtains are extended by a part of the side walls with a width, at least, equal to the maximum thickness of these air curtains. 13. The device according to at least one of claims 1 to 12, wherein the two openings are formed, at least in one of the buffer zones.