EP0447314B1 - Process and device for dynamic separation of two areas - Google Patents

Abstract

In order to ensure a bidirectional dynamic separtion between two zones (10,12), between said zones is formed a gas curtain constituted by three juxtaposed gas streams or jets (28,30,32). The central stream or jet is relatively fast and serves to stabilize the two relatively slow lateral streams or jets (30,32). The latter ensure the relative confinement of the two zones by means of their tongues (30a,32a) and their flow rate is determined in such a way as to supply the relatively fast stream with the gas necessary for its full development. In the case where one (10) of the zones has a reduced volume, a low flow rate, additional gas flow can be injected into the said zone.

Description

The invention relates to a method for ensuring the dynamic separation of two zones, one of these zones possibly being in particular a zone under controlled atmosphere, the confinement of which relative to the external atmosphere must be preserved. The invention also relates to a device for implementing this method.

In industrial sectors as different as the nuclear industry, medicine, biology, and the electronics and food industries, it is often necessary to isolate certain areas from the outside atmosphere, whether to protect people outside these zones in relation to a toxic or dangerous confined atmosphere, on the contrary to prevent a confined atmosphere from being polluted by the surrounding atmosphere, or to simultaneously fulfill these two functions.

In most cases, these constraints lead to delimiting the zones under an atmosphere controlled by watertight walls which ensure the desired confinement. However, whatever the industrial sector concerned, operators can be called upon to intervene in the zone under controlled atmosphere, through the confinement barrier, with a certain degree of freedom of movement. For this reason, it has been necessary in certain cases to replace at least in part the solid wall delimiting the zone under controlled atmosphere by a dynamic barrier preserving the confinement of the zone concerned while allowing easier interventions through this dynamic barrier. .

As illustrated in particular by document EP-A-0 099 818, it has been proposed to protect the outdoor atmosphere vis-à-vis a confined area accessible by an opening and containing dangerous products likely to pollute the outside atmosphere, by creating in this opening a curtain of gas comprising a relatively fast vein located on the side of the outside atmosphere to protect and a relatively slow vein adjacent to the first and located on the side of the area containing the dangerous products.

In this document, in order for the dynamic separation of the two zones to be effective, the dart of the vein is relatively slow, that is to say the zone of this vein in which the injected gas does not mix with the surrounding atmosphere and has a velocity vector equal at all points, has a length at least equal to the length of the opening, so that this dart alone completely separates the two zones. In addition, the rate of injection of gas into the relatively slow vein is substantially equal to the flow induced by the face of the relatively fast vein which is in contact with this relatively slow vein, so that the relatively fast vein can develop fully without that its course is not bent on one side or the other.

In a gas curtain thus produced, the relatively slow vein ensures the effective separation between the two zones thanks to its sting, and the relatively fast vein stabilizes the relatively slow vein by serving as a "dynamic tutor".

These characteristics make it possible to avoid any passage of the polluted atmosphere from the confined zone into the external atmosphere, since any movement of air or gas in this direction collides with the dart of the relatively slow vein, which then takes support on the vein relatively fast. This dynamic confinement however allows multiple interventions at any point of the gas barrier.

On the other hand, the dynamic barrier thus created is not effective in the other direction. Indeed, a current of air or gas coming from the external atmosphere and directed towards the confined zone risks bending the sting of the relatively slow vein towards this latter zone, thus leading to the rupture of the confinement.

Furthermore and in a known manner, a moving gas stream creates on both sides of its path a depression all the greater the higher the gas speed. This depression sucks in the surrounding gas and leads to a gradual widening of the vein as it progresses. This enlargement supposes, of course, that sufficient gas is present on either side of the relatively rapid gas stream. Otherwise, this vein will tend to bend on the side where the gas supply is insufficient.

In the case of the gas curtain described in document EP-A-0 099 818, the relatively fast stream is fed on one side by the relatively slow stream and, on the opposite side, by the external atmosphere.

On the other hand, if the device is used in the opposite direction (that is to say with the relatively fast vein located on the side of the confined area), in order to protect the atmosphere contained in the confined area from the external atmosphere, means must be provided in order to supply gas to the relatively rapid stream on the side of this confined area.

In the latter case, it is therefore necessary to inject a gas at a relatively high rate in the zone under controlled atmosphere. When this gas is a rare gas, this leads to significant consumption which greatly penalizes the operating cost of the installation.

In addition, it is often desirable to have an effective dynamic barrier both in one direction and in the other between two zones, in order for example to protect the exterior vis-à-vis the pollution present in the confined zone, while preserving the confinement of this last compared to the outside.

The object of the present invention is precisely a method and a device for dynamic separation of two zones, designed so as to very significantly reduce the consumption of gas inside these zones and so as to ensure effective dynamic separation in a sense as in the other.

To this end, it is proposed according to the invention a method of dynamic separation of two zones, according to which, in order to protect a first of these zones from the other, a curtain is created between the two zones of gas comprising a relatively fast vein located on the side of the first zone and a relatively slow vein adjacent to the relatively fast vein, on the side of the other zone, the relatively slow vein having a stinger which completely separates the two zones and being injected at a flow rate substantially equal to the flow rate induced by the face of the relatively fast vein which is in contact with this relatively slow vein,
characterized by the fact that the gas curtain thus created further comprises a second relatively slow vein adjacent to the relatively fast vein, on the side of the first zone, this second relatively slow vein having a dart totally separating the two zones and being injected at a flow rate substantially equal to the flow rate induced by the face of the relatively fast vein which is in contact with the second relatively slow vein.

A device is also proposed for the dynamic separation of two zones, comprising a set of nozzles capable of emitting a gas curtain completely separating the two zones, and suction means. of this gas curtain, the set of nozzles comprising, on the side of a first of said zones to be protected vis-à-vis the other zone, a first nozzle capable of emitting a relatively rapid gas stream and, on the side from the other zone, a second nozzle adjacent to the first nozzle and capable of emitting a relatively slow jet, the width of this second nozzle being at least equal to 1/6 ^th of the length of the gas curtain,
characterized by the fact that the nozzle assembly comprises, on the side of the first zone, a third nozzle adjacent to the first nozzle and capable of emitting a relatively slow jet, the width of this third nozzle being at least equal to 1/6 ^e of the length of the gas curtain.

Advantageously, the suction means comprise a suction grid placed opposite the set of nozzles and oriented parallel to this set.

In the case where one of the zones is delimited by an enclosure, means can be provided to diffuse inside this enclosure a stream of gas, at a flow rate which is then very much lower than the gas flow rate which was to be imperatively injected into the devices of the prior art.

• la figure 1 est une vue en coupe représentant de façon très schématique un dispositif conforme à l'invention, assurant la séparation dynamique de deux zones dont l'une est délimitée par une enceinte ; et
• la figure 2 est une vue en perspective, partiellement en coupe, illustrant le dispositif de séparation dynamique de la figure 1, appliqué au confinement d'une zone de travail dans laquelle des manipulations très diverses doivent pouvoir être effectuées.

A preferred embodiment of the invention will now be described, by way of nonlimiting example, with reference to the appended drawings, in which:

• Figure 1 is a sectional view very schematically showing a device according to the invention, ensuring the dynamic separation of two zones, one of which is delimited by an enclosure; and
• Figure 2 is a perspective view, partially in section, illustrating the dynamic separation device of Figure 1, applied to the confinement of a work area in which very diverse manipulations must be able to be carried out.

In accordance with the invention and as very schematically illustrated in FIGS. 1 and 2, the dynamic separation of two zones 10 and 12 is carried out by means of a device mainly comprising a set of nozzles 14 making it possible to create between the two zones 10 and 12 a gas curtain 16, and suction means 18 for this gas curtain.

In the example illustrated, the zone 10 is a confined zone which has the shape of a rectangular parallelepiped delimited on all its faces by a wall 20, with the exception of its front face which is open towards the outside. In particular, we see in Figure 2 the floor 20a, the ceiling 20b and the vertical bottom 20c of this wall 20. The front face of the area 10 is open to define an access opening whose upper edge supports over its entire length the set of nozzles 14, fixed to the ceiling 20b and whose lower edge supports over its entire length the suction means 18, fixed to the floor 20a.

It will easily be understood that the device according to the invention can be used in many other cases, whether to ensure the dynamic confinement of an area delimited by an enclosure having one or more openings of different shapes, or to delimit, at the 'interior of a room, a confined area without the help of any material wall. The latter applies in particular to the protection of an operating bed or table from a circular, rectangular or other ramp overlooking the area concerned and carrying the set of nozzles.

The physical and chemical characteristics inside the confined zone 10, such as temperature, hygrometry, gas concentration, etc., can be controlled as desired by known means.

As illustrated in Figure 1, all of nozzles 14 comprises, in accordance with the invention, three juxtaposed nozzles designated respectively by the references 22, 24 and 26. In practice, each of these nozzles consists of a box, for example of rectangular section, open on the side of the opening formed in the wall 20, that is to say facing the suction means 18, for example in the form of a grid.

The opening of the central nozzle 24 has a relatively small width (for example, about 6 mm), so that the speed of the gas stream 28 leaving this nozzle 24 is relatively fast (for example, about 4 m / s ), for a low flow rate (for example, around 100 m³ / h). On the contrary, the nozzles 22 and 26, which are placed respectively on the side of the zone 10 and on the side of the zone 12 and preferably have identical characteristics, have an orifice whose width is relatively large (for example, about 200 mm ), so that, for an average gas injection rate inside these nozzles (for example, about 440 m³ / h), the gas streams 30 and 32 leaving these nozzles have a relatively low speed ( for example, about 0.4 m / s).

In accordance with a first essential characteristic of the invention, the darts 30a and 32a of the gas streams 30 and 32, that is to say the zones of these gas streams in which the speed vector remains identical as well as regards its module as regards its direction, have a length at least equal to the height of the opening in which the device according to the invention ensures dynamic separation between zones 10 and 12. In other words, the darts 30a and 32a both ensure complete dynamic separation between zones 10 and 12. In the case illustrated in FIG. 1, in which the height of the opening is defined by the distance separating the assembly nozzles 14 of the suction means 18, the length of each of the darts 30a and 32a is at least equal to this distance.

In practice, given that the length of the sting of a gas stream is approximately 6 times the width of the slot formed in the nozzle through which this gas stream is emitted, the width of the slots formed in the nozzles 22 and 26 is therefore equal to at least about 1/6 ^th of the distance separating the assembly of nozzles 14 from the suction means 18. In the example cited where the width of the slots of the nozzles 22 and 26 is approximately 200 mm, the height of the protected opening is therefore, at most, equal to approximately 1200 mm.

In the device according to the invention, there is therefore a dynamic double separation between the zones 10 and 12, provided by each of the darts 30a and 32a of the relatively slow veins 30 and 32.

Given the relatively low speed of the gas streams 30 and 32, each of these streams could be deflected, for example under the effect of an air current between zones 10 and 12, in the absence of the relatively fast gas stream 28. However, the speed of the gaseous vein 28 emitted by the nozzle 24 is high enough for this vein to serve as a support for each of the veins 30 and 32. The latter are thus stabilized and any risk of rupture of the confinement resulting from their deformation due any possible draft is suppressed.

In known manner, a gaseous vein exiting a nozzle comprises, in addition to the aforementioned dart whose width gradually decreases away from the nozzle, a zone of full development of the jet, the width of which on the contrary gradually increases in s' away from the nozzle, and in which the gas injected by the nozzle mixes, by suction, with the surrounding gas. In this zone of full development of the jet, the gas emitted by the nozzle "feeds" on the surrounding gas. As is easily understood, the quantity of surrounding gas which must be supplied to a developing gas stream is all the more important the higher the speed of the gas inside this stream. In fact, the depression created by the vein is then greater and the quantity of gas necessary to fill it is therefore greater.

If this observation is applied to the device according to the invention, it is observed that the relatively fast gas stream 28 coming from the nozzle 24 must be fed by the relatively slow gas streams 30 and 32 coming from the nozzles 22 and 26, since the stream 28 is located directly between these veins 30 and 32. Consequently, the relatively fast gas stream 28 is fed entirely by the relatively slow gas streams 30 and 32. In order for the latter to correctly fulfill this function, the flow of gas from the nozzles 22 and 26 must be adjusted in order to supply the relatively rapid gas stream 28 with the quantity of gas necessary for its full development. In other words, the gas flow injected by the nozzles 22 and 26 must be substantially equal to the flow induced by each of the faces of the relatively fast gas stream 28 in contact with the relatively slow gas streams 30 and 32 respectively.

Since the gaseous veins 30 and 32 are relatively slow, the supply of gas necessary for their full development respectively on the face of the vein 30 facing the zone 10 and on the face of the vein 32 facing the zone 12 is relatively small. Consequently, if the volume of zones 10 and 12 is large enough, it appears practically useless to carry out a gas supply in these zones to compensate for the quantity of gas which is used to feed the gas streams 30 and 32.

In the case illustrated in FIGS. 1 and 2 where one of the zones such as zone 10 has a relatively small volume, it may be useful to regularly introduce into this volume a stream of gas used to compensate for the part of this gas. which is taken up by the gas stream 30. However, due to the low speed of this gas stream, the flow rate of this stream of filler gas remains very low compared to that which is necessary in the prior art for feeding the relatively fast gas stream when it is directly in contact with the atmosphere confined inside the room.

The suction means 18 advantageously consist of a grid 34 which extends parallel to the set of nozzles 14, opposite this set, over its entire length and over a width which takes account of the development of the jets 30 and 32 This grid 34 constitutes the upper wall of a suction chamber 35 (FIG. 2).

Between this suction chamber 35 and the nozzle assembly 14 is placed a gas circuit (not shown), generally closed, which makes it possible to recycle the gas recovered through the grid 34 and to reinject it by the assembly of nozzles 14 with a controlled flow, to take account in particular of the requirements mentioned above. This circuit, which can in particular be designed in a manner comparable to that which is described in document EP-A-0 099 818, comprises means making it possible to aspirate the curtain of gas formed by the veins 28, 30 and 32 through the grid 34, means for purifying this gas, and means for reinjecting it into each of the nozzles of the set of nozzles 14 with the desired flow rate. This circuit, which can be realized so arbitrary by a person skilled in the art taking into account these different imperatives, is not part of the invention.

The foregoing description clearly shows that the device according to the invention makes it possible to create a gas curtain of symmetrical structure formed from three juxtaposed gas streams and ensuring, on the one hand, protection of the area 10 against vis-à-vis zone 12 and, on the other hand, protection of zone 12 vis-à-vis zone 10. The first protection is ensured against any current of gas tending to pass through the zone 12 the atmosphere contained in zone 10, by the assembly formed by the dart 30a of the relatively slow gas stream 30 and by the relatively fast gas stream 28 which stabilizes the stream 30. Protection against any current gas tending to pass into zone 10 the atmosphere contained in zone 12 is provided for its part by the sting 32a of the relatively slow gas stream 32, this gas stream 32 being stabilized by the relatively fast gas stream 28. Cross-protection is particularly useful in many industrial applications, in particular when zone 10 contains an atmosphere which must at all costs be protected against pollution of the external atmosphere contained in zone 12 and in which the atmosphere in zone 10 could be dangerous if it reached the outside atmosphere of zone 12.

When no obstacle crosses the three gas streams emitted by the set of nozzles 14, the gas curtain formed by this set therefore ensures complete isolation of the controlled area 10 from the outside area 12 and, conversely , an insulation of the external zone 12 with respect to the controlled zone 10.

In the presence of an obstacle (such as a manipulator arm intervening from zone 12 in zone 10) moving slowly, one also notes the maintenance of the insulation between these zones.

As illustrated in FIG. 2, the rear face 20c of the wall 20 delimiting the controlled zone 10 comprises, in the example described, a double wall internally delimiting a gas inlet chamber 36 which communicates with the zone 10 by perforations 38. The chamber 36 is connected to a gas source (not shown) so that the gaseous atmosphere of the zone 10 is renewed at a controlled rate, which is optimized according to the dimensions of the perforations 38, so that it does not modify the direction of the gas streams leaving the nozzle assembly 14.

As previously mentioned, the use of a set of nozzles 14 emitting three juxtaposed gas streams comprising a relatively fast intermediate stream 28 and two relatively slow side streams 30 and 32 makes it possible to very significantly reduce the amount of gas introduced into zone 10 compared to previous devices in which the relatively rapid vein was directly in contact with the atmosphere contained in the controlled zone. Thus, a flow rate of a few m³ / h is sufficient in the case of FIG. 2, whereas the prior devices would have required a flow rate of approximately 470 m³ / h.

In FIG. 2, one of the multiple intervention possibilities offered by the dynamic separation device according to the invention is also illustrated, by way of example only, inside the controlled zone 10.

In this example, a master / slave manipulator 40 passes through the gas curtain formed by the nozzle assembly 14, so that the master arm 42 is located in the external zone 12 and the slave arm 44 in the confined zone 10. The central block 46 of this remote manipulator 40 is mounted on a support 48 linked to a carriage 50 capable of moving on rails 52 fixed on the ceiling 20b and extending in a direction parallel to the opening formed on the front face of the wall 20, that is to say to the set of nozzles 14 and to the suction means 18.

Thanks to this arrangement, it is possible, by means of a single manipulator, to intervene at any point of the zone 10, whatever the length thereof.

The central block 46, which crosses the gas streams 28, 30 and 32, has the effect of cutting the darts 30a and 32a. However, due to the slowness of the jets 30 and 32, there is no separation of the gas flowing in these two gas streams from the obstacle formed by the crossing block 46. In addition, the stream intermediate gas 28 allows, thanks to its speed, to immediately evacuate a large part of the contaminants possibly diffused in the slow jets. Therefore, the dynamic separation between zones 10 and 12 is preserved.

The presence of an additional current of gas in the enclosure brings an additional guarantee of non-pollution of the atmosphere of the enclosure by the pollutants of zone 12.

Of course, the gas curtain obtained using the dynamic separation device according to the invention can be crossed by any other tools or members allowing an operator to intervene from the outside, at any point in the zone 10 It can in particular be a light gripping tool maneuvered by the operator from the outside, or even the operator's arms.

The dynamic separation obtained using the three juxtaposed gas streams can be used to isolate a specific area inside a larger room, without this area being delimited by any material barrier. Furthermore, the arrangement of the assembly of nozzles and suction means can be produced differently, these two elements not necessarily being placed on the horizontal edge of an opening.

Claims (4)

1. Process for the dynamic separation of two zones (10, 12), according to which, in order to protect a first (10) of the said zones with respect to the other, between the said two zones is formed a gas certain having a relatively fast stream (28) located on the side of the first zone and a relatively slow stream (32) adjacent to the relatively fast stream on the side of the other zone (12), the relatively slow stream having a tongue (32a) which completely separates the two zones and is injected at a flow rate substantially equal to that induced by the face of the relatively fast stream in contact with said relatively slow stream, characterized in that the thus formed gas curtain also has a second relatively slow stream (30) adjacent to the relatively fast stream (28) on the side of the first zone (10), said second relatively slow stream having a tongue (30a) completely separating the two zones and being injected at a flow rate substantially equal to that induced by the face of the relatively fast stream in contact with the second relatively slow stream.
2. Apparatus for the dynamic separation of two zones having a plurality of nozzles (14) able to discharge a gas certain completely separating the two zones, and suction means (18) for the said gas certain, the plurality of nozzles having on the side of a first (10) of said zones to be protected from the other zone, a first nozzle (24) able to discharge a relatively fast gas stream (28) and on the side of the other zone (12), a second nozzle (26) adjacent to the first nozzle and able to discharge a relatively slow stream (32), the width of said second nozzle being at least equal to 1/6 of the length of the gas curtain, characterized in that the plurality of nozzles comprises, on the side of the first zone (10), a third nozzle (22) adjacent to the first nozzle and able to discharge a relatively slow stream (30), the width of said third nozzle being at least equal to 1/6 of the length of the gas curtain.
3. Apparatus according to claim 2, characterized in that the suction means comprise a suction grid or grating (34) positioned facing the plurality of nozzles (14) and oriented parallel to the latter.
4. Apparatus according to either of the claims 2 and 3, characterized in that one of the zones being defined by an enclosure (20), means (38) are provided for diffusing into the latter a gas flow at a relatively low rate, which is substantially equal to the flow rate induced by the face of the relatively slow stream (30) adjacent to the zone defined by the enclosure (20).

Images