Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
  • F24F9/00—Use of air currents for screening, e.g. air curtains
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
  • F24F9/00—Use of air currents for screening, e.g. air curtains
  • F24F2009/007—Use of air currents for screening, e.g. air curtains using more than one jet or band in the air curtain

Definitions

• the invention relates to a method for ensuring the dynamic separation of a contaminating zone and a zone to be protected, communicating with each other by at least one separation zone, by means of a curtain of clean air obtained by injecting in the separation zone at least two adjacent clean air jets in the same direction.
• the process according to the invention can be used in numerous industrial sectors.
• a first family of industries concerned by this process includes all industries (food, medical, biotechnology, high technology, etc.), in which it is necessary to prevent the atmosphere of a given work area from being contaminated by ambient air, carrying thermal, microbial, particulate and / or gaseous contamination.
• Another family of industries concerned by the process according to the invention includes industries (nuclear, chemical, medical, etc.) in which man and his environment must be protected from toxic or dangerous products placed at inside a containment.
• Ventilation protection and air curtain protection There are currently two types of solutions to ensure the dynamic separation of two zones communicating with each other by one or more separation zones in order, for example, to allow the entry and exit of objects: ventilation protection and air curtain protection.
• Protection by ventilation consists in artificially creating a pressure difference between the two zones, so that the pressure prevailing in the zone to be protected is greater than the pressure which prevails inside the contaminating zone.
• the area to be protected contains a product liable to be contaminated by ambient air
• a laminar flow which blows outward through the separation area is injected into the area to be protected.
• the dynamic confinement is ensured by implementing an extraction ventilation in this contaminated space.
• a rule of thumb imposes a minimum speed of the ventilated air of 0.5 m / s, in the plane of the separation zone through which the two zones communicate, in order to avoid transfer of contamination to the area to be protected.
• this ventilation protection technique is however not perfect, especially in a so-called "break-in" situation, that is to say when objects are transferred through the separation zone interposed between the two zones.
• this type of protection requires treating and controlling, as the case may be, the entire clean area to be protected from the contaminating external atmosphere or the entire contaminated area. When the area to be treated and controlled is large, this entails a cost of equipment and particularly important functioning.
• this ventilation protection technique only provides one-way protection, that is to say that it only acts when transfers of contamination are only possible in one direction.
• the air curtain protection technique consists in simultaneously injecting, into the separation zone by which the two zones communicate, one or more jets of clean air, adjacent and of the same direction, which form a fictitious gate between the zone to protect and the contaminating area.
• a plane air jet breaks up into two distinct zones: a transition zone (or core zone) and a development zone.
• the transition zone corresponds to the central part of the jet, supported on the nozzle, in which the speed vector is constant. This zone corresponds to the part of the jet in which no mixing between the injected air and the air present on either side of the jet occurs. In section along a plane perpendicular to the plane of the separation zone, the width of the transition zone gradually decreases as it moves away from the nozzle. For this reason, this transition zone will be called “dart" in the remainder of the text.
• the jet development zone is the part of the jet located outside the transition zone. In this jet development zone, the outside air is entrained by the flow of the jet. This results in variations in the speed vector and in air mixing. The entrainment of air by the two faces of the jet, in this development zone pement, is called "induction". An air jet thus induces, on each of its faces, an air flow which depends in particular on the injection flow rate of the jet considered.
• document JP-B-36 7228 it has been proposed to produce an air curtain by simultaneously injecting into the separation zone three adjacent air jets of the same direction. More specifically, a relatively fast air jet is injected between two relatively slow air jets.
• This arrangement is supposed to provide more effective confinement than a single air jet, by the fact that the air entrained and stirred by the central jet is lightly contaminated air, coming from the relatively slow jets injected from both sides. other of this central air jet.
• this document does not take into account either the length of the darts of each of the jets, nor their injection rates, so that the effectiveness of the confinement is very random.
• the dart of the slow jet is sufficiently long to cover the entire opening when the width of the injection nozzle of this slow jet is at least equal to 1/6 of the height of the opening to be protected. It is also indicated that the injection flows of the two air jets must be such that the air flow induced by the face of the fast jet which is in contact with the slow jet is substantially equal to the injection flow of this latest.
• the return grid by which the two jets are recovered is arranged at the ex- inside the opening, and below the workstation, to control the ventilation of the contaminated area.
• the two side walls which delimit the opening are extended outward over a distance at least equal to the thickness of the air curtain.
• the subject of the invention is precisely a method of dynamic separation of two zones communicating with each other by at least one separation zone, using an air curtain whose principle is comparable to that which is described in documents FR-A-2 530 163, FR-A-2 652 520 and FR-A-2 659 782, but the containment efficiency of which is significantly improved, especially in the event of break-ins.
• this result is obtained by means of a process for dynamic separation of a contaminating zone and a zone to be protected, communicating with one another by at least one separation zone, this method comprising the following steps:
• the air curtain can provide dynamic containment in either direction, if we add a relatively slow third jet to the first two jets.
• a third relatively slow jet of clean air is injected into the separation zone, at a third injection rate, adjacent to the second jet and in the same direction as the first and second jets, between the zone to be protected and the second draft.
• the third jet comprises a dart capable of covering the entire separation zone.
• the third injection flow is then adjusted so that it is substantially equal to the first injection flow, so that the air flows induced by the faces of the second jet respectively in contact with the first and third jets are at most substantially equal to half of the first and third injection rates. Thanks to these characteristics, the third jet effectively covers the entire separation zone.
• clean ventilation air is simultaneously injected inside the area to be protected, at an injection rate at least equal to the air flow induced by the second or third jet (depending on whether the curtain includes two or three jets), on the face of it in contact with the clean ventilation air.
• this characteristic makes it possible to obtain a "purifying effect" in the area to be protected, in particular in the event of fractions through the air curtain.
• the clean ventilation air is advantageously injected at a speed such that the speed of this clean ventilation air, brought to the surface. of the plan of the separation zone, ie at least equal to 0.1 m / s.
• clean ventilation air is injected over an entire rear or upper wall of the area to be protected, in the direction of the separation area.
• the wall through which the clean ventilation air is injected is therefore oriented parallel or substantially perpendicular to the plane of the separation zone.
• clean ventilation air is injected at a regulated temperature.
• all the clean air jets are preferably injected in directions substantially parallel to the plane of the separation zone.
• all of the clean air jets are advantageously recovered by a return grid installed opposite the injection nozzles of these jets and situated in a plane substantially perpendicular to the direction of the clean air jets. Optimization of the barrier effect provided by the air curtain can also be obtained by extending the side walls of the opening, located on either side of the clean air jets, so that they extend towards the contaminating zone over a distance at least equal to the maximum thickness of the jets.
• FIG. 1 is a perspective view, which schematically illustrates the protection of a clean work area by means of an air curtain formed of two adjacent air jets, according to a first embodiment the method of the invention.
• FIG. 2 is a perspective view comparable to Figure 1, which schematically illustrates the protection of a clean work area by means of an air curtain formed of three adjacent air jets, according to a second form of implementation of the method of the invention. Detailed description of two forms of implementation
• the areas 10 and 12 have been designated respectively by an area to be protected and a contaminating area.
• the zone 10 to be protected is constituted by the clean interior space of a work station and the contaminating zone 12 is constituted by the space external to this work station.
• This external space constitutes a source of thermal, particulate, gaseous and / or microbial contamination with respect to the internal space of the work station.
• the work station which forms the zone 10 to be protected is delimited by watertight walls in all directions, except to the right when considering figure 1. More precisely, the face of the work station turned to the right in the figure 1 forms a separation zone, constituted by an opening 11, through which the zone 10 to be protected communicates with the contaminating external zone 12.
• This opening 11 is intended, for example, to allow entry and exit of objects into the zone 10 to be protected, as well as possible handling inside this zone, from the contaminating external zone 12.
• this illustration is only an exemplary embodiment, in no way limiting, zones 10 and 12 being able to communicate by one or more separation zones of any orientation and which are not necessarily materialized by openings, without departing from the scope of the invention.
• the separation zone between the contaminating zone and the zone to be protected extends longitudinally along the path of said conveyor.
• an air curtain 14 is permanently formed in this opening when the installation is used. In the embodiment illustrated schematically in Figure 1, this air curtain 14 is formed by simultaneously injecting into the opening two adjacent clean air jets and in the same direction.
• a relatively slow first jet of clean air is injected into the opening 11, of which only the sting 16 is shown, and a second jet of clean air, relatively fast compared to the first jet, of which only the sting 18 is represented.
• the second jet is injected between the first jet and the zone 10 to be protected.
• the first jet and the second jet are called respectively "slow jet” and “fast jet” in the remainder of the text.
• the injections of the slow jet and the rapid jet into the opening 11 are made respectively by juxtaposed nozzles 20 and 22.
• the injection nozzles 20 and 22 extend over the entire length of the upper edge of the opening 11, so that the air curtain 14 is formed over the entire width of the latter.
• the two jets forming the air curtain 14 are then completely recovered by a single return grid 24 which extends along the lower edge of the opening and along the entire length of this edge.
• the vertical edges of the opening 11 are materialized by two side walls 26, located on either side of the two jets forming the air curtain 14. These two side walls 26 extend into the contaminating zone 12 on a distance at least equal to the maximum thickness of the jets.
• the slow jet, injected by the nozzle 20 is dimensioned so that its dart 16 covers the entire plane of the opening 11 to be protected. This result is obtained by ensuring that the range, or length, of the dart 16 is at least equal to the height of the opening 11.
• the width of the nozzle 20, parallel to the plane of the figure 1 is at least equal to
• the width of the nozzle 20 will be at least 0.20 m.
• the speed of the slow jet emitted by the nozzle 20 is advantageously fixed at 0.5 m / s. Because the length of the dart 16 of the slow jet is at least equal to the height of the opening to be protected and that this jet is relatively slow, the air streams follow the outline of the objects which pass through the curtain of air 14, without breaking the confinement.
• the low speed of the slow jet injected by the nozzle 20 however has the consequence that this jet, if it were alone, would risk being destabilized by the aeraulic or mechanical disturbances which may occur near the air curtain, thus causing the rup- containment of the workplace.
• the rapid jet injected by the nozzle 22 is added to the slow jet, the higher speed of which makes it possible to ensure the stability of the first jet and, consequently, to improve the efficiency of the confinement in situation of break-ins through the dynamic barrier formed by the air curtain 14.
• the width of the nozzle 22 by which is injected the j and fast can be equal to about 1/40 of the width of the nozzle 20, which corresponds to 0.005 m in the example described.
• the applicants have established that the speed of injection of the fast jet injected by the nozzle 22 must be adjusted so that the air flow induced by the face of this fast jet which is in contact with the slow jet, injected by the nozzle 20, either lower or, preferably, substantially equal to half the injection rate of this slow jet.
• this characteristic leads to a significant improvement in the barrier effect compared to the prior art, in which the speed of the rapid jet is adjusted so that the air flow induced by the face of this fast jet in contact with the slow jet, ie substantially equal to the injection rate of the slow jet.
• the nozzle 22 is 360 m / h, the blowing rate of the rapid jet injected by the nozzle 22 must be approximately
• the return grille 24 communicates with suction means (not shown), dimensioned for this purpose.
• the air recovered by the return grille 24 is advantageously purified by specific purification means (not shown) before being recycled to the injection nozzles 20 and 22. The excess air is then rejected outside after a second specific purification.
• 3 rework 24 is 825 m / h.
• the barrier effect is further optimized when each of the two jets is injected in a direction substantially parallel to the vertical plane of the opening 11 and when the return grid 24 is perpendicular to this direction.
• a purifying effect of the zone 10 to be protected is obtained by ensuring internal ventilation of this zone and by respecting an injection flow rate determined for this internal ventilation.
• This purifying effect added to the barrier effect provided by the air curtain 14, appreciably improves the efficiency of the confinement, in particular in a crumbling situation. tions.
• the rate of injection of clean ventilation air inside the zone 10 to be protected is at least equal to the air flow induced by the rapid jet, injected by the nozzle 22, on the face of this rapid jet which is in contact with the clean ventilation air, that is to say say on the face of the rapid jet facing the zone 10 to be protected.
• the clean ventilation air is injected at a speed such that the speed of this air, relative to the surface of the plane of the opening 11, is at least equal to 0.1 m / s.
• the injection of clean ventilation air inside the zone 10 to be protected is carried out by a blowing grille 28 which extends over the entire rear wall of the area to be protected, that is to say over the entire wall of the working area facing the opening 11 and oriented parallel to the vertical plane thereof.
• the supply grille 28 through which the clean ventilation air is injected is located on the left, considering FIG. 1.
• the wall through which the clean ventilation air is injected forming the purifying flow is the upper wall of the area to be protected. This wall is arranged opposite the conveyor and then oriented substantially perpendicular to the plane of the separation zone.
• the clean ventilation air is injected through the blowing grille 28 at a regulated temperature.
• temperature regulation means such as a heat exchanger (not shown), are placed in the ventilation circuit, upstream of the blowing grid 28.
• FIG. 2 a second form of implementation of the method according to the invention is illustrated.
• This second form of implementation essentially takes up the characteristics described above with reference to FIG. 1, by adding a third jet, relatively slow, between the rapid jet and the area to be protected.
• the elements of the installation illustrated in FIG. 2 which are identical to those of the installation described above with reference to FIG. 1 are designated by the same reference numbers and no detailed description will be made of them.
• Figure 2 the area
• the contaminating zone 12 the opening 11, the nozzles 20 and 22 through which the slow jet and the fast jet are injected respectively, the respective darts of which are illustrated in 16 and 18, the side walls 26 of the opening 11 and the blowing grid 28 ensuring the internal ventilation of the zone 10 to be protected.
• the air curtain designated in this case by the reference 14 ', further comprises a third jet of clean air, relatively slow compared to the rapid jet, which is emitted by a nozzle 30 adjacent to the nozzle 22, between the rapid jet and zone 10 to be protected, so as to be adjacent to the rapid jet and in the same direction as the other jets.
• the sting of this third jet is illustrated at 32 in FIG. 2.
• the dimensions of the nozzle 30 are chosen so that the dart 32 of the third jet covers the entire opening.
• the nozzle 30 extends, like the nozzles 20 and 22, over the entire length of the upper edge of the opening 11, and the width of this nozzle 30 is ⁇ ,. ,, -diag,,,, _. , s ⁇ / c th, at least equal to 1/6 and preferably 1/5 of the height of the opening 11.
• the widths of the nozzles 20 and 30 are the same and, for example , of 0.20 m in the case of the digital illustration given above, without limitation, with reference to FIG. 1.
• the injection rate is adjusted tion of the slow jet delivered by the nozzle 30, so that this flow is substantially equal to the injection flow of the slow jet delivered by the nozzle 20.
• the air flows induced by the faces of the fast jet, emitted by the nozzle 22, respectively in contact with each of the slow jets are less than or, preferably, substantially equal to half the injection rates of these slow jets.
• the width of the return grille is adapted to the width of the air curtain, so that all the jets are recovered by this grid 24 '. More precisely, the grid 24 'for the return of the air curtain 14' formed by three jets is wider than the grid 24 for the return of the air curtain 14, formed by two jets.
• the presence of another slow jet, between the rapid jet and the zone 10 to be protected makes it possible to reduce the injection rate of the internal ventilation by compared to the first form of implementation.
• the rate of injection of clean ventilation air by the blowing grid 28 is then at least equal to the air flow induced by the slow jet emitted by the nozzle 30, on the face of this third jet which is in contact with clean ventilation air.
• the injection rate of each of the slow jets is 3 of 360 m / h
• 3 24 'return grid is 1185 m / h.
• the three jets are preferably injected in directions parallel to the plane of the opening 11 and the return grid is placed below the injection nozzles 20, 22 and 30 and oriented perpendicular to this plane. Furthermore, the speed at which the ventilation air is injected into the zone 10 to be protected is advantageously at least equal to 0.1 m / s.
• the possible modifications also relate to the shape, the orientation and the number of the separation zones by which the two zones communicate, as well as the choice of the edges of the separation zone on which the injection nozzles and the return grid are located. , which may be different from those which have been described.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Ventilation (AREA)
• Container, Conveyance, Adherence, Positioning, Of Wafer (AREA)
• Separation By Low-Temperature Treatments (AREA)
• Devices For Use In Laboratory Experiments (AREA)
• Duct Arrangements (AREA)
• Filtering Of Dispersed Particles In Gases (AREA)
• Electrolytic Production Of Metals (AREA)
• Separation Using Semi-Permeable Membranes (AREA)

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• 1996
  • 1996-12-10 FR FR9615151A patent/FR2756910B1/fr not_active Expired - Fee Related
• 1997
  • 1997-12-09 JP JP52629098A patent/JP3651805B2/ja not_active Expired - Fee Related
  • 1997-12-09 EP EP97951278A patent/EP0944802B1/de not_active Expired - Lifetime
  • 1997-12-09 ES ES97951278T patent/ES2167803T3/es not_active Expired - Lifetime
  • 1997-12-09 AT AT97951278T patent/ATE208484T1/de not_active IP Right Cessation
  • 1997-12-09 AU AU54867/98A patent/AU725184B2/en not_active Ceased
  • 1997-12-09 CA CA002274147A patent/CA2274147C/fr not_active Expired - Fee Related
  • 1997-12-09 DE DE69708144T patent/DE69708144T2/de not_active Expired - Fee Related
  • 1997-12-09 PT PT97951278T patent/PT944802E/pt unknown
  • 1997-12-09 US US09/319,255 patent/US6334812B2/en not_active Expired - Fee Related
  • 1997-12-09 CN CN97180461.3A patent/CN1240022A/zh active Pending
  • 1997-12-09 WO PCT/FR1997/002238 patent/WO1998026226A1/fr active IP Right Grant
  • 1997-12-09 DK DK97951278T patent/DK0944802T3/da active

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