EP0911588B1 - Process and device for confinement using thermal stratification - Google Patents

Process and device for confinement using thermal stratification Download PDF

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Publication number
EP0911588B1
EP0911588B1 EP98402641A EP98402641A EP0911588B1 EP 0911588 B1 EP0911588 B1 EP 0911588B1 EP 98402641 A EP98402641 A EP 98402641A EP 98402641 A EP98402641 A EP 98402641A EP 0911588 B1 EP0911588 B1 EP 0911588B1
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EP
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Prior art keywords
volume
fluid
enclosure
slots
hot
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EP98402641A
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German (de)
French (fr)
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EP0911588A1 (en
Inventor
Guillaume Mehlman
François Meline
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Orano Cycle SA
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Compagnie Generale des Matieres Nucleaires SA
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    • 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

Definitions

  • the subject of the present invention is a method and a device for containment. It relates more precisely to a process for confining pollution generated in the upper or lower volume (s) of a filled enclosure fluid and a device associated with said process.
  • Said process - industrial - is original in that it is based on the natural phenomenon of stratification thermal. Its implementation can, surprisingly, ensure containment effective in different contexts and especially in the most unfavorable one, where a hot polluting source is placed in the lower part of a enclosure whose upper part is to be protected from said polluting source.
  • the Applicant has particularly developed the process and device for the invention in the context of vitrification of industrial fission products to protect against pollution from the melting pot and the calciner of equipment of the lifting unit type, arranged in the upper part of the vitrification cell. Said method and device of the invention, described in details below, are however not limited to this context.
  • the stratification phenomenon is much more unstable and the interface is less straightforward than that which prevails between liquid phases.
  • the interface is replaced by a mixing zone , due to Brownian and turbulent diffusion, in which the average concentration of one phase in the other varies continuously with a high gradient when we move along the vertical axis.
  • said natural phenomenon of thermal stratification could, surprisingly, be controlled, exploited for artificially create in horizontal planes real containment barriers, both in liquids and gases.
  • Such mastery the skilled person would readily agree, was not obvious. He appeared in fact very little likely to reach it, especially in a gaseous atmosphere, very sensitive to convection and turbulence currents. There was, in fact, a real prejudice unfavorable, to base an industrial confinement process on this phenomenon natural thermal stratification.
  • the invention therefore relates to a containment process pollution generated in the upper or lower volume (s) an enclosure filled with fluid - gas, generally air or liquid, generally water by thermal stratification: the average temperature of said higher volume is maintained sufficiently above temperature average of said lower volume so that said two volumes are separated by a turbulent intermediate zone of small thickness, called mixing zone, at the within which a high temperature gradient is maintained; said intermediate zone constitutes, in a horizontal plane, a containment barrier dynamic, acting as a virtual partition.
  • Said method consists in artificially creating a containment barrier between the upper and lower volumes of the enclosure, maintaining a gap sufficiently large temperature between said upper and lower volumes (the temperature of said upper volume obviously being maintained above the temperature of said lower volume).
  • Said temperature difference must ensure a sufficiently high density difference between the hot fluid of the upper volume and cold volume of the lower volume.
  • Said difference must in fact be such that the work of the vertical forces pointing downwards for the fluid cold - or upwards for hot fluid - (said forces, due to the thrust Archimedes, are applied to the various volume elements of the two phases, and tend to separate them by stratification), which is preponderant vis-à-vis work inertial forces due to the speed of penetration of said volume elements into the mixing zone. These are due to the random speeds that prevail in the turbulence of the atmosphere and are responsible for mixing by diffusion and heat exchanges between phases.
  • the method of the invention can be implemented works in an enclosure filled with gas (we speak more readily then of a cell or room) or in an enclosure filled with liquid (such as a swimming pool).
  • a single fluid, gas or liquid generally intervenes.
  • the gas we have seen that it generally consists of air; regarding the liquid, into water.
  • other gases such as nitrogen for example or other liquids is in no way excluded from the scope of the invention.
  • it is not not totally excluded from bringing two or two gases into an enclosure liquids of different nature. However, in such a case, care is taken to ensure that that the densities of said two intervening fluids are compatible with the implementation of the process.
  • the method of the invention in fact ensures the respective confinement of the two upper and lower volumes of the enclosure, pollution being generated in a single of said volumes and the other then being protected from it or pollution being generated in each of said volumes and each of said volumes being then protected from the pollution generated in the other.
  • Pollution can be diverse in nature. Its source can, for example, consist of a mechanical source of radioactive dust in particular (such as sawing station, shearing station, or welding station, generally positioned at the bottom of an enclosure; such a position can however be perfectly positioned at the top of an enclosure, especially in the context of work on lead into the top of an appliance, such as a rocket) or into a possibly hot charge emitting vapors charged with particles (such as melting pot and calciner, arranged at the bottom of a vitrification cell. fission products).
  • a mechanical source of radioactive dust in particular (such as sawing station, shearing station, or welding station, generally positioned at the bottom of an enclosure; such a position can however be perfectly positioned at the top of an enclosure, especially in the context of work on lead into the top of an appliance, such as a rocket) or into a possibly hot charge emitting vapors charged with particles (such as melting pot and calciner, arranged at the bottom of a vitrification cell. fission products).
  • Such a source of pollution can be cold or hot, arranged in upper and / or lower part of the enclosure. All cases are possible, the most unfavorable case being that of the hot polluting source placed in the bottom of the enclosure. Pollution from such a source naturally tendency, by convection, to pollute the upper zone.
  • the process of the invention which can be effectively implemented in these different cases is also effective in this delicate context, particularly delicate if one operates in a gaseous atmosphere.
  • the two upper and lower volumes are, so independent, swept by a fluid, at an adequate temperature; said fluid, injected into the upper volume, being taken up just above the interface upper of the mixing zone (containment barrier) and said fluid, injected in the lower volume, being taken up just below the lower interface of said mixing zone; said fluids, of identical or different nature, being injected, into each of said volumes, under conditions such as the component the vertical speed of the turbulence generated is minimized.
  • the hot fluid sweeping the upper volume of the enclosure is, in the part of an advantageous variant of implementation of the invention, at least in part recycled.
  • a containment barrier maintaining a sufficient temperature difference important between the lower part (cold zone) and the upper part (zone warm) from the speaker.
  • This temperature difference can be generated by any means. We have seen, above, that advantageously, it results from a scanning of said parts lower and upper with a fluid (s) at suitable temperatures.
  • said means for maintaining suitable temperatures the upper and lower volumes of the enclosure can decline according to several variants and that in any event it is interesting to insulating said upper volume. Indeed, it is interesting, on the one hand, to reduce heat exchange and, on the other hand, avoid too great a difference in temperature between said walls of said upper volume and the ambient atmosphere. Such a large temperature difference is likely to cause currents of convection and harmful turbulence.
  • the fluid hot in the upper volume (more precisely, in the lower part of said volume upper) and cold fluid in the lower volume (more precisely, in part high of said lower volume) slots of small width, uniformly distributed on the same level, facing each other, over the entire length of two vertical walls opposite of the enclosure.
  • said slots do not do not weaken the structure of the vertical walls including them. They are actually divided into a plurality of elements (slots). Assuming an enclosure rectangular person, the skilled person will understand that said slots recovery are advantageously arranged along the longitudinal (horizontal) axis of said enclosure.
  • a floor and / or a ceiling is provided (or even a false floor or / and false ceiling) of the enclosure, perforated, on at least part of its surface, constituting a diffusing wall of the injected fluid.
  • longitudinal slots are used, generally at least two to ensure effective scanning. Said slots can be fitted in the same way, in a false ceiling or a false floor.
  • two series of slots are provided, at the bottom and / or the top of vertical walls of the enclosure. These slots are staggered - (the two series are advantageously regularly offset) - to minimize the turbulence generated during injection.
  • Those, arranged in the lower volume of the enclosure are, advantageously, not at floor level (or false floor) but slightly above it. This avoids mixing the settled dust on said floor (or false floor).
  • the device of the invention can involve in the volumes upper and lower of the enclosure the same type of fluid emission device or different type fluid emission devices.
  • the fluid emission device in the higher or lower volume (s) within which one (s) pollution is generated, is of type c) above. This type of device is really optimized to minimize the component vertical velocity of turbulence generated at injection.
  • the means of the device of the invention provided for scanning greater volume with a hot fluid advantageously include means for at least partially recycling said hot fluid.
  • the means of the device of the invention provided for sweep the lower volume with a cold fluid, are advantageously supplied by a fluid at room temperature or by a fluid cooled upstream, advantageously by means of a heat pump which uses the calories taken from said fluid to raise the temperature of the fluid supplying the hot fluid emission device.
  • vitrification cells fission products which have a hot spring at a low level contaminant and which are equipped in their upper part with a lifting bridge.
  • the description which follows is in fact generalizable to any context of this type, in which there is a contaminating hot spring below and equipment, requiring periodic maintenance operations, to be protected, above.
  • Figure 1 there is shown schematically, in cut, such a cell.
  • Figure 3 shows a profile of temperatures within the Figure 2 cell.
  • FIG. 5 is a section on V of said FIG. 4.
  • FIG. 6 is an enlargement of part of said FIG. 5.
  • FIGS. 1 and 2 there is, within the cell, the source pollutant 1 (melting pot + calciner, diagrammatic) and the lifting bridge 2, to be protected of said polluting source 1. Said cell is filled with air.
  • the technical problem that the Applicant faced was that of significantly limiting the contamination of lifting units in such cells.
  • the air heated and contaminated by the melting pot and the calciner 1 rises in the cell as in a chimney, and to the extent where this air is loaded with radioactive particles, it contaminates the bridge of lifting 2 in the upper part of the cell, thereby making it much more complex all maintenance operations for this equipment.
  • the return experience has shown that the availability of the lifting units present in the cells containing hot pollution sources is directly related to their degree of contamination.
  • the cell has the following dimensions: Length 12.0 m Width 3.6m Height under crows of the lifting bridge 7.5m Total height 9.0 m
  • FIG. 1 a ventilation system had been put in place to protect said bridge 2.
  • Air was introduced into the upper part of the cell (above the melting pot) and was taken from the lower part of the opposite wall. Said air was blown at a temperature of 28 ° C at a flow rate of 4,300 Nm 3 / h.
  • a confinement barrier 3 is created, in a horizontal plane, maintaining a sufficiently large temperature difference between the lower part (cold zone) 4 and the upper part (hot zone) 5 of the cell.
  • Said temperature difference is maintained by a ventilation system appropriate and must be such that the result of the gravitational forces applying to a cold air volume element which would enter the hot zone 5 or greater than the inertial forces applying to this same element, bringing this cold air volume element to descend to the bottom of the cell until level where it is at equilibrium, thus preventing it from going to contaminate the bridge lifting 2 in the upper part 5 of the cell.
  • this thickness is even smaller than the temperature difference between zones is larger.
  • the ventilation is designed as if it should ensure the rate of air renewal in two separate superimposed cells (4 and 5) and separated by a material volume whose thickness would be that of the area of mix 3. These two virtual cells (or zones) are supplied with a flow air that has undergone the usual treatment of ventilation air from reprocessing units.
  • the air outlets A and D are arranged so that they produce in each zone 5 and 4 respectively, a flow at low speed vertical permanent (a few cm / s) and whose random component must be as small as possible.
  • the flow in the lower (cold) zone 4 is oriented from bottom to top, the one in the upper (hot) zone 5 from top to bottom.
  • This stabilization requires a sufficiently precise control of the ratio of supply and extract air flows from the hot and cold air circuits, the solution the simplest to implement in this regard being the recycling of hot air which also has the advantage of saving thermal energy associated with reduction in size of the heating batteries.
  • Insulation of the side walls of the upper zone 5, which reduces heat exchange and parasitic convection currents, is an element favorable to the stability of the mixing zone 3.
  • the temperature in the upper zone 5 must be as high as possible, it is only limited by the cooling constraint of the the lifting unit.
  • the supply air flow rate of the lower volume 4 is a function of the intensity of the sources of pollution and their nature, and mainly the total power released by the thermal sources it contains; warming of the resulting average air temperature to be compensated for by the cold air flow.
  • the constraint of limiting the thickness of the mixture layer 3 (therefore of the speed of penetration and the speed of upward flow of air through a horizontal cross section), determines in each case the maximum value admissible flow.
  • the equal distribution of the blowing rate of the ventilation outlets A, D on the one hand, and extraction rates of the return slots B, C on the other hand, is a essential for effective stratification.
  • Supply ducts for air outlets A, D and ducts extraction slots B, C must be designed according to this constraint (blading of fans, variable duct sections, etc.). Therefore, and taking into account the possible congestion which results therefrom, the dimensioning study ducts is an essential element in the design of the device, a study which must precede that of the civil engineering of the cell.
  • the cell can indeed be designed with internal double walls in heat-insulating (for example in expanded glass); the space on the order of 0.4 m between these walls and those of the civil engineering of the cell then being available for the sheaths and supply air distribution devices.
  • the air outlets A, D which are more "inductive” (that is to say which induce internal circulation movements) should be as far away from mixing zone 3 as possible, while the return slots B, C whose induction effect on the environment is very limited in space can be located as close as possible to mixing zone 3 of which they limit and stabilize the limits on the vertical walls of the cell.
  • the air outlets can be arranged (taking into account the method of fixing the lifting unit) according to narrow slots, parallel to the longitudinal axis of the cell and practically continuous.
  • the hot air flow is chosen to ensure a flow rate of about 0.04 m / s across the area of the horizontal section of the upper volume 5.
  • the flow near the upper plane of mixing zone 3 can be likened to a laminar flow where the turbulent diffusion is negligible, and, for the finest polluting particles (whose diffusion is the fastest), the Brownian diffusion speed is very less than 0.04 m / s.
  • the arrangement and geometry of the cold air emission outlets D have for the purpose of optimizing the concentration of polluted air and hot air in the atmosphere of the lower zone (cold zone) 4, while limiting the component vertical of the random velocities of the induced turbulence.
  • the narrow D emission outlets (in the form of loopholes) are located near the floor on the longest sides of the cell and arranged in staggered rows.
  • jet planes produce, by the shearing effect due to the velocities opposite, vortices whose velocities have small vertical components and which cause the currents from various sources to mix with the atmosphere (see figure 5).
  • the value of the average ascent speed of the air is chosen from about 0.04 m / s to limit the entrainment of polluting particles by the air of ventilation of the lower zone 4 to those whose "aerodynamic diameter" is less than 35 ⁇ m. Particles with a larger diameter tend to decant in the cell are not very adherent to the walls and fall under the dust removal by aspiration.
  • This speed defines a flow depending on the area of the horizontal section of the cell which must also be sufficient to ensure, taking into account the cold air supply temperature and hot spring power 1, maintaining a sufficiently low temperature in the cold zone 4.
  • a cooling battery supply air may be required to limit its flow.
  • the use of a heat pump raising the air temperature warm by lowering that of cold air may be the most rational solution.
  • the cold air C and hot air B return slots are arranged in horizontal lines constituting practically continuous slits (intervals between vertical sides of the suction outlets as small as possible), these lines horizontal facing each other on the two longest sides.
  • the upper level of the cold air return slots C limits the plane of the mixing zone 3, while the lower level of the hot air intake B limits the upper plane of said mixing zone 3.
  • the upper level of the hot air return slots B must be located approximately 1 m below the lower level of the volume in which the lifting unit operates. In the case of a bridge garage, the upper level of the slots hot air return must be below the level of the floor of the garage.

Description

La présente invention a pour objet un procédé et un dispositif de confinement. Elle concerne plus précisément un procédé de confinement de la pollution générée dans le(s) volume(s) supérieur ou(et) inférieur d'une enceinte remplie de fluide et un dispositif associé audit procédé. Ledit procédé - industriel -est original en ce qu'il est basé sur le phénomène naturel de la stratification thermique. Sa mise en oeuvre peut, de manière surprenante, assurer un confinement efficace dans différents contextes et notamment dans celui le plus défavorable, où une source polluante chaude est disposée en partie basse d'une enceinte dont on souhaite protéger, de ladite source polluante, la partie haute. La Demanderesse a tout particulièrement développé les procédé et dispositif de l'invention dans le contexte de la vitrification des produits de fission de l'industrie nucléaire, en vue de protéger de la pollution émanant du pot de fusion et du calcinateur des équipements du type unités de levage, disposés en partie haute de la cellule de vitrification. Lesdits procédé et dispositif de l'invention, décrits en détail ci-après, ne sont toutefois nullement limités à ce contexte.The subject of the present invention is a method and a device for containment. It relates more precisely to a process for confining pollution generated in the upper or lower volume (s) of a filled enclosure fluid and a device associated with said process. Said process - industrial - is original in that it is based on the natural phenomenon of stratification thermal. Its implementation can, surprisingly, ensure containment effective in different contexts and especially in the most unfavorable one, where a hot polluting source is placed in the lower part of a enclosure whose upper part is to be protected from said polluting source. The The Applicant has particularly developed the process and device for the invention in the context of vitrification of industrial fission products to protect against pollution from the melting pot and the calciner of equipment of the lifting unit type, arranged in the upper part of the vitrification cell. Said method and device of the invention, described in details below, are however not limited to this context.

Selon l'art antérieur, le phénomène de la stratification des fluides est bien connu.According to the prior art, the phenomenon of fluid stratification is indeed known.

Cas des liquidesLiquids

La stratification gravitique de liquides non miscibles de masses volumiques différentes est d'observation courante ; elle est très stable et nécessite une énergie importante pour provoquer le mélange des deux phases (émulsion). En l'absence d'émulsion, l'aire de l'interface par unité de volume, relativement faible, constitue une barrière efficace contre le transfert d'un soluté ou de particules en suspension d'une phase dans l'autre.Gravitic stratification of immiscible liquids of masses different volumes is common observation; it is very stable and requires significant energy to cause the mixture of the two phases (emulsion). In the absence of an emulsion, the area of the interface per unit of volume, relatively weak, constitutes an effective barrier against the transfer of a solute or particles in suspension from one phase to another.

Cas des gazGas case

Un phénomène similaire peut s'observer, si les deux phases sont des gaz de masses volumiques différentes situés dans une enceinte de grand volume où l'ambiance est peu perturbée.A similar phenomenon can be observed, if the two phases are gases different densities located in a large volume enclosure where the atmosphere is little disturbed.

Dans ce cas, le phénomène de stratification est beaucoup plus instable et l'interface est moins franche que celle qui règne entre phases liquides. L'interface est remplacée par une zone de mélange, due à la diffusion brownienne et turbulente, dans laquelle la concentration moyenne d'une phase dans l'autre varie de façon continue avec un gradient élevé quand on se déplace suivant l'axe vertical.In this case, the stratification phenomenon is much more unstable and the interface is less straightforward than that which prevails between liquid phases. The interface is replaced by a mixing zone , due to Brownian and turbulent diffusion, in which the average concentration of one phase in the other varies continuously with a high gradient when we move along the vertical axis.

En référence, plus particulièrement à la stratification thermique, on sait que des différences de masse volumique existent pour un même fluide en raison de différences de température; ledit fluide pouvant alors se comporter comme deux phases distinctes, l'une froide, l'autre chaude. Ces deux phases sont peu miscibles si les volumes mis en jeu sont importants et elles peuvent donc présenter les mêmes phénomènes de stratification que dans le cas de fluides de composition distincte. Ainsi, explique-t-on, par ce phénomène naturel de la stratification thermique :

  • les courants marins,
  • le phénomène météorologique d'inversion de température et ses incidences sur la pollution atmosphérique,
  • le profil de température (en fonction de la profondeur) des eaux d'un lac de montagne.
With reference, more particularly to thermal stratification, it is known that differences in density exist for the same fluid due to differences in temperature; said fluid can then behave as two distinct phases, one cold, the other hot. These two phases are hardly miscible if the volumes involved are large and they can therefore exhibit the same stratification phenomena as in the case of fluids of distinct composition. Thus, we explain, by this natural phenomenon of thermal stratification:
  • sea currents,
  • the meteorological phenomenon of temperature inversion and its effects on air pollution,
  • the temperature profile (as a function of depth) of the waters of a mountain lake.

Dans le cadre de la présente invention, ledit phénomène naturel de la stratification thermique a pu, de manière surprenante, être maítrisé, exploité pour créer artificiellement dans des plans horizontaux de véritables barrières de confinement, tant au sein de liquides que de gaz. Une telle maítrise, l'homme du métier en conviendra aisément, n'avait rien d'évident. Il paraissait en fait fort peu probable de l'atteindre, notamment dans une atmosphère gazeuse, très sensible aux courants de convection et aux turbulences. Il existait, en fait, un réel préjugé défavorable, à baser un procédé industriel de confinement sur ce phénomène naturel de la stratification thermique.In the context of the present invention, said natural phenomenon of thermal stratification could, surprisingly, be controlled, exploited for artificially create in horizontal planes real containment barriers, both in liquids and gases. Such mastery, the skilled person would readily agree, was not obvious. He appeared in fact very little likely to reach it, especially in a gaseous atmosphere, very sensitive to convection and turbulence currents. There was, in fact, a real prejudice unfavorable, to base an industrial confinement process on this phenomenon natural thermal stratification.

Des procédés de confinement, connus, mis en oeuvre à l'époque du développement de l'invention et de nos jours, pour protéger notamment un équipement d'une atmosphère polluante chargée en particules, sont du type :

  • protection rapprochée avec intervention d'un capotage ;
  • protection par rideaux d'air ;
  • protection sous flux laminaire ;
  • protection basée sur la thermophorèse.
Containment methods, known, implemented at the time of the development of the invention and nowadays, in particular for protecting equipment from a polluting atmosphere loaded with particles, are of the type:
  • close protection with intervention of a rollover;
  • protection by air curtains;
  • protection under laminar flow;
  • protection based on thermophoresis.

L'homme du métier, après avoir pris connaissance de la présente invention, appréciera, dans tel ou tel contexte, les avantages de celle-ci sur les techniques de l'art antérieur mentionnées ci-dessus. On peut d'ores et déjà souligner ici l'efficacité du procédé de l'invention et l'encombrement limité des équipements annexes nécessaires à sa mise en oeuvre.A person skilled in the art, after having read the present invention, will appreciate, in such or such context, the advantages of this one on the prior art techniques mentioned above. We can already emphasize here the efficiency of the process of the invention and the limited space taken up by additional equipment necessary for its implementation.

On se propose de décrire maintenant l'invention sous ses deux aspects - procédé, dispositif - dans une première partie, de manière générale puis, dans une seconde partie, de façon plus détaillée, en référence à un mode de réalisation particulier. We now propose to describe the invention in its two aspects - process, device - in a first part, in general then, in a second part, in more detail, with reference to an embodiment particular.

Selon son premier objet, l'invention concerne donc un procédé de confinement de la pollution générée dans le(s) volume(s) supérieur ou(et) inférieur d'une enceinte remplie de fluide - de gaz, généralement d'air où de liquide, généralement d'eau par stratification thermique : la température moyenne dudit volume supérieur est maintenue suffisamment supérieure à la température moyenne dudit volume inférieur de sorte que lesdits deux volumes sont séparés par une zone intermédiaire turbulente de faible épaisseur, dite zone de mélange, au sein de laquelle se maintient un gradient de température élevé ; ladite zone intermédiaire constitue, dans un plan horizontal, une barrière de confinement dynamique, faisant office de cloison virtuelle.According to its first object, the invention therefore relates to a containment process pollution generated in the upper or lower volume (s) an enclosure filled with fluid - gas, generally air or liquid, generally water by thermal stratification: the average temperature of said higher volume is maintained sufficiently above temperature average of said lower volume so that said two volumes are separated by a turbulent intermediate zone of small thickness, called mixing zone, at the within which a high temperature gradient is maintained; said intermediate zone constitutes, in a horizontal plane, a containment barrier dynamic, acting as a virtual partition.

Ledit procédé consiste à créer artificiellement une barrière de confinement entre les volumes supérieur et inférieur de l'enceinte, en maintenant un écart de température suffisamment important entre lesdits volumes supérieur et inférieur (la température dudit volume supérieur étant évidemment maintenue supérieure à la température dudit volume inférieur). Ledit écart de température doit assurer une différence de masse volumique suffisamment élevée entre le fluide chaud du volume supérieur et celui froid du volume inférieur. Ladite différence doit en fait être telle que le travail des forces verticales orientées vers le bas pour le fluide froid - ou vers le haut pour le fluide chaud - (lesdites forces, dues à la poussée d'Archimède, sont appliquées aux divers éléments de volume des deux phases, et tendent à les séparer par stratification), soit prépondérant vis-à-vis du travail forces d'inertie dues à la vitesse de pénétration desdits éléments de volume dans la zone de mélange. Ces dernières sont dues aux vitesses aléatoires qui règnent dans les turbulences de l'ambiance et sont responsables du mélange par diffusion et des échanges thermiques entre phases. On partage artificiellement selon l'invention l'enceinte en deux enceintes distinctes.Said method consists in artificially creating a containment barrier between the upper and lower volumes of the enclosure, maintaining a gap sufficiently large temperature between said upper and lower volumes (the temperature of said upper volume obviously being maintained above the temperature of said lower volume). Said temperature difference must ensure a sufficiently high density difference between the hot fluid of the upper volume and cold volume of the lower volume. Said difference must in fact be such that the work of the vertical forces pointing downwards for the fluid cold - or upwards for hot fluid - (said forces, due to the thrust Archimedes, are applied to the various volume elements of the two phases, and tend to separate them by stratification), which is preponderant vis-à-vis work inertial forces due to the speed of penetration of said volume elements into the mixing zone. These are due to the random speeds that prevail in the turbulence of the atmosphere and are responsible for mixing by diffusion and heat exchanges between phases. We share artificially according to the invention the enclosure into two separate enclosures.

Comme précisé ci-dessus, le procédé de l'invention peut être mis en oeuvre dans une enceinte remplie de gaz (on parle alors plus volontiers d'une cellule ou d'une salle) ou dans une enceinte remplie de liquide (telle une piscine). Un unique fluide, gaz ou liquide, intervient généralement. Pour ce qui concerne le gaz, on a vu qu'il consiste généralement en de l'air; pour ce qui concerne le liquide, en de l'eau. L'intervention d'autres gaz, tels l'azote par exemple ou d'autres liquides n'est nullement exclue du cadre de l'invention. De la même façon, il n'est pas totalement exclu de faire intervenir au sein d'une enceinte deux gaz ou deux liquides de nature différente. On veille toutefois, dans une telle hypothèse, à ce que les masses volumiques desdits deux fluides intervenant soient compatibles avec la mise en oeuvre du procédé.As specified above, the method of the invention can be implemented works in an enclosure filled with gas (we speak more readily then of a cell or room) or in an enclosure filled with liquid (such as a swimming pool). A single fluid, gas or liquid, generally intervenes. Regarding the gas, we have seen that it generally consists of air; regarding the liquid, into water. The intervention of other gases, such as nitrogen for example or other liquids is in no way excluded from the scope of the invention. Similarly, it is not not totally excluded from bringing two or two gases into an enclosure liquids of different nature. However, in such a case, care is taken to ensure that that the densities of said two intervening fluids are compatible with the implementation of the process.

Le procédé de l'invention assure en fait le confinement respectif des deux volumes supérieur et inférieur de l'enceinte, la pollution étant générée dans un seul desdits volumes et l'autre se trouvant alors protégé de celle-ci ou une pollution étant générée dans chacun desdits volumes et chacun desdits volumes se trouvant alors protégé de la pollution générée dans l'autre.The method of the invention in fact ensures the respective confinement of the two upper and lower volumes of the enclosure, pollution being generated in a single of said volumes and the other then being protected from it or pollution being generated in each of said volumes and each of said volumes being then protected from the pollution generated in the other.

La pollution peut être de nature diverse. Sa source peut, par exemple, consister en une source mécanique de poussières notamment radioactives (tel un poste de sciage, un poste de cisaillage, ou un poste de soudage, positionné généralement dans le bas d'une enceinte ; un tel poste peut toutefois parfaitement être positionné dans le haut d'une enceinte, notamment dans un contexte de travaux à mener dans la partie supérieure d'un appareillage, telle une fusée) ou en une charge éventuellement chaude émettant des vapeurs chargées de particules (tel le pot de fusion et le calcinateur, disposés dans le bas d'une cellule de vitrification de . produits de fission).Pollution can be diverse in nature. Its source can, for example, consist of a mechanical source of radioactive dust in particular (such as sawing station, shearing station, or welding station, generally positioned at the bottom of an enclosure; such a position can however be perfectly positioned at the top of an enclosure, especially in the context of work on lead into the top of an appliance, such as a rocket) or into a possibly hot charge emitting vapors charged with particles (such as melting pot and calciner, arranged at the bottom of a vitrification cell. fission products).

Une telle source de pollution peut être froide ou chaude, disposée en partie haute et/ou basse de l'enceinte. Tous les cas de figure sont envisageables, le cas le plus défavorable étant celui de la source polluante chaude disposée dans le bas de l'enceinte. La pollution émanant d'une telle source a en effet naturellement tendance, par convection, à polluer la zone supérieure. Le procédé de l'invention qui peut être efficacement mis en oeuvre dans ces différents cas de figure est également efficace dans ce contexte délicat, particulièrement délicat si l'on opère en atmosphère gazeuse.Such a source of pollution can be cold or hot, arranged in upper and / or lower part of the enclosure. All cases are possible, the the most unfavorable case being that of the hot polluting source placed in the bottom of the enclosure. Pollution from such a source naturally tendency, by convection, to pollute the upper zone. The process of the invention which can be effectively implemented in these different cases is also effective in this delicate context, particularly delicate if one operates in a gaseous atmosphere.

Pour maintenir les volumes supérieur et inférieur de l'enceinte à des températures telles que la stratification thermique se mette en place de façon stable, on fait intervenir des moyens adéquats. Selon une variante avantageuse du procédé de l'invention, les deux volumes supérieur et inférieur sont, de manière indépendante, balayés par un fluide, à une température adéquate ; ledit fluide, injecté dans le volume supérieur, étant repris juste au-dessus de l'interface supérieure de la zone de mélange (barrière de confinement) et ledit fluide, injecté dans le volume inférieur, étant repris juste en dessous de l'interface inférieure de ladite zone de mélange ; lesdits fluides, de nature identique ou différente, étant injectés, dans chacun desdits volumes, dans des conditions telles que la composante verticale de la vitesse des turbulences générées est minimisée.To maintain the top and bottom volumes of the speaker at temperatures such that thermal layering takes place so stable, adequate resources are involved. According to an advantageous variant of the method of the invention, the two upper and lower volumes are, so independent, swept by a fluid, at an adequate temperature; said fluid, injected into the upper volume, being taken up just above the interface upper of the mixing zone (containment barrier) and said fluid, injected in the lower volume, being taken up just below the lower interface of said mixing zone; said fluids, of identical or different nature, being injected, into each of said volumes, under conditions such as the component the vertical speed of the turbulence generated is minimized.

Cette variante avantageuse peut être mise en oeuvre aussi bien

  • avec un gaz (voire deux gaz: on se reporte au texte ci-dessus) tel l'air ; soufflé, chaud, dans le volume supérieur et soufflé, froid, dans le volume inférieur ; qu'
  • avec un liquide (voire deux liquides : on se reporte au texte ci-dessus) tel l'eau ; injecté, chaud, dans le volume supérieur et injecté, froid, dans le volume inférieur.
This advantageous variant can be implemented as well
  • with a gas (or even two gases: we refer to the text above) such as air; blown, hot, in the upper volume and blown, cold, in the lower volume; that
  • with a liquid (or even two liquids: we refer to the text above) such as water; injected, hot, in the upper volume and injected, cold, in the lower volume.

En tout état de cause, pour une efficacité optimale, qui passe par une stabilisation de la barrière de confinement générée, on veille à injecter lesdits fluides chaud et froid "dans des conditions douées". La reprise desdits fluides est évidemment avantageusement réalisée dans de telles conditions mais les perturbations générées à ce niveau sont moins dommageables. Il convient donc que les perturbations générées par l'injection soient minimisées. A cette fin, on minimise la composante verticale de la vitesse des turbulences générées. Avantageusement, à cette même fin, on cherche a obtenir une équirépartition des vitesses à la section de sortie des moyens d'injection et l'on dispose lesdits moyens d'injection, le plus loin possible, de la zone de mélange constituant la barrière de confinement. On comprend qu'inversement les moyens de reprise des fluides injectés sont situés au plus près de ladite zone de mélange.In any case, for optimal efficiency, which requires a stabilization of the generated containment barrier, care is taken to inject the said hot and cold fluids "in gifted conditions". The recovery of said fluids is obviously advantageously carried out under such conditions but the disturbances generated at this level are less damaging. It is therefore appropriate that the disturbances generated by the injection are minimized. To this end, we minimizes the vertical component of the speed of the turbulence generated. advantageously, to this same end, we seek to obtain an equal distribution of the speeds at the outlet section of the injection means and said injection means are arranged, as far as possible from the mixing zone constituting the barrier containment. It is understood that, conversely, the means for taking up fluids injected are located as close as possible to said mixing zone.

Le fluide chaud balayant le volume supérieur de l'enceinte est, dans le cadre d'une variante avantageuse de mise en oeuvre de l'invention, au moins en partie recyclé.The hot fluid sweeping the upper volume of the enclosure is, in the part of an advantageous variant of implementation of the invention, at least in part recycled.

Selon le procédé de l'invention, on crée donc, dans un plan horizontal, une barrière de confinement, en maintenant un écart de température suffisamment important entre la partie inférieure (zone froide) et la partie supérieure (zone chaude) de l'enceinte. Cet écart de température peut être généré par tout moyen. On a vu, ci-dessus, qu'avantageusement, il résulte d'un balayage desdites parties inférieure et supérieure par un(des) fluide(s) à des températures adéquates.According to the method of the invention, therefore, in a horizontal plane, a containment barrier, maintaining a sufficient temperature difference important between the lower part (cold zone) and the upper part (zone warm) from the speaker. This temperature difference can be generated by any means. We have seen, above, that advantageously, it results from a scanning of said parts lower and upper with a fluid (s) at suitable temperatures.

On se propose maintenant d'aborder le second objet de la présente invention, à savoir un dispositif convenant à la mise en oeuvre du premier objet de celle-ci, à savoir le procédé de confinement décrit ci-dessus. Ledit dispositif de confinement de la pollution générée dans le(s) volume(s) supérieur ou(et) inférieur d'une enceinte remplie fluide - de gaz, généralement d'air ou de liquide, généralement d'eau - comprend, de façon caractéristique:

  • des moyens pour maintenir la température moyenne dudit volume supérieur supérieure à la température moyenne dudit volume inférieur en créant dans un plan horizontal, entre lesdits deux volumes supérieur et inférieur, une barrière de confinement : zone intermédiaire turbulente de faible épaisseur, dite zone de mélange, au sein de laquelle se maintient un gradient de température élevé ;
  • et avantageusement, des moyens de calorifugeage d'au moins certaines parois dudit volume supérieur.
We now propose to approach the second object of the present invention, namely a device suitable for the implementation of the first object thereof, namely the confinement process described above. Said device for confining the pollution generated in the upper or lower volume (s) of an enclosure filled with fluid - gas, generally air or liquid, generally water - comprises, so feature:
  • means for maintaining the average temperature of said upper volume greater than the average temperature of said lower volume by creating in a horizontal plane, between said two upper and lower volumes, a confinement barrier: turbulent intermediate zone of small thickness, called mixing zone, within which a high temperature gradient is maintained;
  • and advantageously, means for insulating at least some walls of said upper volume.

L'homme du métier conçoit que lesdits moyens pour maintenir aux températures adéquates les volumes supérieur et inférieur de l'enceinte peuvent se décliner selon plusieurs variantes et qu'en tout état de cause il est intéressant de calorifuger ledit volume supérieur. En effet, il est intéressant, d'une part, de réduire les échanges thermiques et d'autre part, d'éviter un trop grand écart de température entre lesdites parois dudit volume supérieur et l'atmosphère ambiante. Un tel grand écart de température est susceptible de provoquer des courants de convection et des turbulences nuisibles.A person skilled in the art understands that said means for maintaining suitable temperatures the upper and lower volumes of the enclosure can decline according to several variants and that in any event it is interesting to insulating said upper volume. Indeed, it is interesting, on the one hand, to reduce heat exchange and, on the other hand, avoid too great a difference in temperature between said walls of said upper volume and the ambient atmosphere. Such a large temperature difference is likely to cause currents of convection and harmful turbulence.

Dans le cadre de la variante avantageuse du procédé de l'invention selon laquelle les deux volumes supérieur et inférieur sont balayés par un fluide maintenu à une température adéquate, on préconise de faire intervenir titre de moyens pour maintenir les températures respectives adéquates dans chacun desdits volumes, des moyens qui incluent, convenablement disposés dans chacun desdits volumes, des dispositifs d'émission, et de reprise d'un fluide aptes à assurer le balayage de chacun desdits volumes. Lesdits dispositifs d'émission ont leurs formes et dimensions optimisées pour réduire la composante verticale de la vitesse des turbulences générées. Lesdits dispositifs d'émission et de reprise sont évidemment reliés, respectivement en amont et en aval, à des moyens adéquats pour leur alimentation en fluide à la température désirée, d'une part et pour leur aspiration dudit fluide ayant balayé le volume concerné (supérieur ou inférieur), d'autre part.In the context of the advantageous variant of the method of the invention according to which the two upper and lower volumes are swept by a fluid maintained at an adequate temperature, it is recommended to involve means to maintain the respective respective temperatures in each of said volumes, means which include, suitably arranged in each said volumes, devices for emitting and taking up a fluid capable of ensuring scanning each of said volumes. Said transmitting devices have their shapes and dimensions optimized to reduce the vertical component of speed turbulence generated. Said emission and recovery devices are obviously connected, respectively upstream and downstream, to adequate means for their supply of fluid at the desired temperature, on the one hand and for their aspiration said fluid having swept the volume concerned (higher or lower), on the other hand.

On préconise de faire intervenir, titre de dispositif de reprise, du fluide chaud dans le volume supérieur (plus précisément, en partie basse dudit volume supérieur) et du fluide froid dans le volume inférieur (plus précisément, en partie haute dudit volume inférieur) des fentes, de faible largeur, réparties uniformément à un même niveau, en vis-à-vis, sur toute la longueur de deux parois verticales opposées de l'enceinte. On veille bien évidemment à ce que lesdites fentes ne fragilisent pas la structure des parois verticales les incluant. Elles sont en fait divisées en une pluralité d'éléments (de fentes). Dans l'hypothèse d'une enceinte parallélépipédique rectangle, l'homme du métier comprendra que lesdites fentes de reprise sont avantageusement disposées selon l'axe longitudinal (horizontal) de ladite enceinte. It is recommended to use, as a recovery device, the fluid hot in the upper volume (more precisely, in the lower part of said volume upper) and cold fluid in the lower volume (more precisely, in part high of said lower volume) slots, of small width, uniformly distributed on the same level, facing each other, over the entire length of two vertical walls opposite of the enclosure. Obviously, it is ensured that said slots do not do not weaken the structure of the vertical walls including them. They are actually divided into a plurality of elements (slots). Assuming an enclosure rectangular person, the skilled person will understand that said slots recovery are advantageously arranged along the longitudinal (horizontal) axis of said enclosure.

On préconise de faire intervenir, à titre de dispositif d'émission du fluide chaud dans le volume supérieur (plus précisément, en partie haute dudit volume supérieur) et/ou de dispositif d'émission du fluide froid dans le volume inférieur (plus précisément, en partie basse dudit volume inférieur) :

  • a) une surface horizontale assurant une distribution continue dudit fluide ;
       ou
  • b) au moins deux fentes, de faible largeur, réparties uniformément, parallèlement, sur toute la longueur d'une paroi horizontale (plafond et/ou plancher) de l'enceinte ;
       ou
  • c)deux séries de fentes, de faibles largeur et hauteur, réparties régulièrement en quinconce sur toute la longueur de deux parois verticales opposées de l'enceinte ; lesdites fentes commençant au niveau ou à proximité des parois horizontales ou de la paroi horizontale (plafond et/ou plancher) au contact desdites deux parois verticales.
    • It is recommended to use, as a device for emitting hot fluid in the upper volume (more precisely, in the upper part of said upper volume) and / or as a device for emitting cold fluid in the lower volume (more precisely, in the lower part of said lower volume):
  • a) a horizontal surface ensuring a continuous distribution of said fluid;
    or
  • b) at least two slits, of small width, distributed uniformly, in parallel, over the entire length of a horizontal wall (ceiling and / or floor) of the enclosure;
    or
  • c) two series of slits, of small width and height, distributed regularly in staggered rows over the entire length of two opposite vertical walls of the enclosure; said slots starting at or near the horizontal walls or the horizontal wall (ceiling and / or floor) in contact with said two vertical walls.

    • Selon la variante a), on prévoit un plancher ou/et un plafond (voire un faux plancher ou/et un faux plafond) de l'enceinte, perforé, sur au moins une partie de sa surface, constituant une paroi diffusante du fluide injecté.According to variant a), a floor and / or a ceiling is provided (or even a false floor or / and false ceiling) of the enclosure, perforated, on at least part of its surface, constituting a diffusing wall of the injected fluid.

    Selon la variante b), on fait intervenir des fentes longitudinales, généralement au moins deux pour assurer un balayage efficace. Lesdites fentes peuvent être aménagées de la même façon, dans un faux plafond ou un faux plancher.According to variant b), longitudinal slots are used, generally at least two to ensure effective scanning. Said slots can be fitted in the same way, in a false ceiling or a false floor.

    Selon la variante c), on prévoit deux séries de fentes, dans le bas et/ou le haut de parois verticales de l'enceinte. Ces fentes sont réparties en quinconce - (les deux séries sont avantageusement régulièrement décalées) - pour minimiser la turbulence générée à l'injection. Celles, agencées dans le volume inférieur de l'enceinte ne le sont, avantageusement, pas au niveau du plancher (ou faux plancher) mais légèrement au-dessus de celui-ci. On évite ainsi de brasser les poussières décantées sur ledit plancher (ou faux plancher).According to variant c), two series of slots are provided, at the bottom and / or the top of vertical walls of the enclosure. These slots are staggered - (the two series are advantageously regularly offset) - to minimize the turbulence generated during injection. Those, arranged in the lower volume of the enclosure are, advantageously, not at floor level (or false floor) but slightly above it. This avoids mixing the settled dust on said floor (or false floor).

    Le dispositif de l'invention peut faire intervenir dans les volumes supérieur et inférieur de l'enceinte le même type de dispositif d'émission de fluide ou des dispositifs d'émission de fluide de type différent. Selon une variante avantageuse, dans le(s) volume(s) supérieur ou(et) inférieur au sein du(des)quel(s) la pollution est générée, le dispositif d'émission du fluide est du type c) ci-dessus. Ce type de dispositif est réellement optimisé pour minimiser la composante verticale de la vitesse des turbulences générées à l'injection. The device of the invention can involve in the volumes upper and lower of the enclosure the same type of fluid emission device or different type fluid emission devices. According to a variant advantageous, in the higher or lower volume (s) within which one (s) pollution is generated, the fluid emission device is of type c) above. This type of device is really optimized to minimize the component vertical velocity of turbulence generated at injection.

    On associe avantageusement à ce type de dispositif agencé dans le volume supérieur ou inférieur pollué un dispositif du type b) ci-dessus dans le volume inférieur ou supérieur correspondant non pollué (dans l'hypothèse où de la pollution n'est générée que dans l'un desdits deux volumes supérieur et inférieur).It is advantageously associated with this type of device arranged in the higher or lower volume polluted a device of type b) above in the corresponding lower or higher unpolluted volume (assuming that pollution is only generated in one of said two upper and lower volumes).

    Les moyens du dispositif de l'invention, prévus pour assurer le balayage du volume supérieur avec un fluide chaud comprennent avantageusement des moyens pour recycler, au moins partiellement, ledit fluide chaud.The means of the device of the invention, provided for scanning greater volume with a hot fluid advantageously include means for at least partially recycling said hot fluid.

    De la même façon, les moyens du dispositif de l'invention, prévus pour assurer le balayage du volume inférieur avec un fluide froid, sont avantageusement alimentés par un fluide à la température ambiante ou par un fluide refroidi en amont, avantageusement au moyen d'une pompe à chaleur qui utilise les calories prélevées sur ledit fluide pour élever la température du fluide alimentant le dispositif d'émission de fluide chaud.In the same way, the means of the device of the invention, provided for sweep the lower volume with a cold fluid, are advantageously supplied by a fluid at room temperature or by a fluid cooled upstream, advantageously by means of a heat pump which uses the calories taken from said fluid to raise the temperature of the fluid supplying the hot fluid emission device.

    Dans le cadre de l'invention, on peut ainsi par différents biais (calorifugeage, recyclage, échangeurs de chaleur) optimiser le rendement énergétique du procédé.Within the framework of the invention, it is thus possible by various means (thermal insulation, recycling, heat exchangers) optimize the energy efficiency of process.

    Selon une variante de réalisation, convenant notamment pour confiner la pollution émanant d'une source polluante, éventuellement chaude, disposée en partie basse d'une enceinte remplie de gaz, généralement d'air, le dispositif de l'invention comprend ;

    • dans son volume inférieur, un dispositif d'émission de gaz, généralement d'air froid, du type c) ci-dessus ;
    • dans son volume supérieur; un dispositif d'émission de gaz, généralement d'air chaud, du type b) ci-dessus ;
    • dans ses volumes supérieur et inférieur, un dispositif de reprise du gaz, généralement de l'air, injecté, du type fente, tel que précisé ci-dessus.
    According to an alternative embodiment, suitable in particular for confining pollution emanating from a polluting source, possibly hot, disposed in the lower part of an enclosure filled with gas, generally air, the device of the invention comprises;
    • in its lower volume, a device for emitting gas, generally cold air, of type c) above;
    • in its upper volume; a device for emitting gas, generally hot air, of type b) above;
    • in its upper and lower volumes, a device for taking up gas, generally air, injected, of the slit type, as specified above.

    Cette variante est illustrée ci-après.This variant is illustrated below.

    On se propose maintenant de décrire plus précisément, en référence aux figures annexées, l'invention dans un contexte particulier qui constitue un exemple.We now propose to describe more precisely, with reference to attached figures, the invention in a particular context which constitutes a example.

    Ledit contexte particulier est celui déjà évoqué des cellules de vitrification des produits de fission, qui comportent en niveau bas une source chaude contaminante et qui sont équipées dans leur partie supérieure d'un pont de levage. La description qui suit est en fait généralisable à tout contexte de ce type, dans lequel on trouve une source chaude contaminante en bas et des équipements, nécessitant des opérations de maintenance périodique, à protéger, en haut. Said particular context is that already mentioned of vitrification cells fission products, which have a hot spring at a low level contaminant and which are equipped in their upper part with a lifting bridge. The description which follows is in fact generalizable to any context of this type, in which there is a contaminating hot spring below and equipment, requiring periodic maintenance operations, to be protected, above.

    Sur la figure 1 (art antérieur), on a représenté schématiquement, en coupe, une telle cellule.In Figure 1 (prior art), there is shown schematically, in cut, such a cell.

    Sur la figure 2, on a représenté, de la même façon, une telle cellule, au sein de laquelle le procédé de confinement de l'invention - confinement par stratification thermique - est mis en oeuvre.In Figure 2, there is shown, in the same way, such a cell, at within which the confinement process of the invention - confinement by stratification thermal - is implemented.

    Sur la figure 3, on a montré un profil des températures au sein de la cellule de la figure 2.Figure 3 shows a profile of temperatures within the Figure 2 cell.

    Sur la figure 4, on a représenté en perspective ladite cellule de la figure 2 équipée d'un dispositif de confinement de l'invention.In Figure 4, there is shown in perspective said cell of Figure 2 equipped with a containment device of the invention.

    La figure 5 est une coupe selon V de ladite figure 4.FIG. 5 is a section on V of said FIG. 4.

    La figure 6 est un agrandissement d'une partie de ladite figure 5.FIG. 6 is an enlargement of part of said FIG. 5.

    Sur lesdites figures 1 et 2, on trouve, au sein de la cellule, la source polluante 1 (pot de fusion + calcinateur, schématisé) et le pont de levage 2, à protéger de ladite source polluante 1. Ladite cellule est remplie d'air.In said FIGS. 1 and 2, there is, within the cell, the source pollutant 1 (melting pot + calciner, diagrammatic) and the lifting bridge 2, to be protected of said polluting source 1. Said cell is filled with air.

    Le problème technique auquel la Demanderesse a été confrontée a été celui de limiter, de façon significative, la contamination des unités de levage dans de telles cellules. En effet, l'air réchauffé et contaminé par le pot de fusion et le calcinateur 1 s'élève dans la cellule comme dans une cheminée, et dans la mesure où cet air est chargé de particules radioactives, il vient contaminer le pont de levage 2 dans la partie haute de la cellule, rendant de ce fait beaucoup plus complexes toutes les opérations de maintenance de cet équipement. Or, le retour d'expérience a montré que la disponibilité des unités de levage présentes dans les cellules contenant des sources de pollution chaudes est directement liée à leur degré de contamination.The technical problem that the Applicant faced was that of significantly limiting the contamination of lifting units in such cells. The air heated and contaminated by the melting pot and the calciner 1 rises in the cell as in a chimney, and to the extent where this air is loaded with radioactive particles, it contaminates the bridge of lifting 2 in the upper part of the cell, thereby making it much more complex all maintenance operations for this equipment. The return experience has shown that the availability of the lifting units present in the cells containing hot pollution sources is directly related to their degree of contamination.

    Dans le cadre de l'exemple et de l'étude complète menée par la Demanderesse, étude dont on donne plus avant dans le présent texte les résultats (tableau de l'exemple), la cellule présente les dimensions ci-après : Longueur 12,0 m Largeur 3,6 m Hauteur sous corbeaux du pont de levage 7,5 m Hauteur totale 9,0 m In the context of the example and of the complete study carried out by the Applicant, a study for which the results are given further in this text (table of the example), the cell has the following dimensions: Length 12.0 m Width 3.6m Height under crows of the lifting bridge 7.5m Total height 9.0 m

    Selon l'art antérieur (figure 1), on avait mis en place un système de ventilation, pour protéger ledit pont 2. De l'air était introduit dans la partie supérieure de la cellule (au-dessus du pot de fusion) et était repris en partie inférieure du mur situé à l'opposé. Ledit air était insufflé à la température de 28°C à un débit de 4 300 Nm3/h. According to the prior art (FIG. 1), a ventilation system had been put in place to protect said bridge 2. Air was introduced into the upper part of the cell (above the melting pot) and was taken from the lower part of the opposite wall. Said air was blown at a temperature of 28 ° C at a flow rate of 4,300 Nm 3 / h.

    Selon l'invention (figure 2), on crée une barrière de confinement 3, dans un plan horizontal, en maintenant un écart de température suffisamment important entre la partie inférieure (zone froide) 4 et la partie supérieure (zone chaude) 5 de la cellule.According to the invention (FIG. 2), a confinement barrier 3 is created, in a horizontal plane, maintaining a sufficiently large temperature difference between the lower part (cold zone) 4 and the upper part (hot zone) 5 of the cell.

    Ledit écart de température est maintenu par un système de ventilation approprié et doit être tel que la résultante des forces de gravitation s'appliquant à un élément de volume d'air froid qui pénétrerait dans la zone chaude 5 soit supérieure aux forces d'inertie s'appliquant à ce même élément, amenant cet élément de volume d'air froid à redescendre vers le bas de la cellule jusqu'au niveau où il se trouve à l'équilibre, en l'empêchant donc d'aller contaminer le pont de levage 2 dans la partie supérieure 5 de la cellule.Said temperature difference is maintained by a ventilation system appropriate and must be such that the result of the gravitational forces applying to a cold air volume element which would enter the hot zone 5 or greater than the inertial forces applying to this same element, bringing this cold air volume element to descend to the bottom of the cell until level where it is at equilibrium, thus preventing it from going to contaminate the bridge lifting 2 in the upper part 5 of the cell.

    La barrière de confinement 3 est une zone de mélange dans le volume de laquelle le gradient de température suivant une verticale est très élevé vis-à-vis de celui qui règne dans les deux volumes 4 et 5 extérieurs à cette zone 3 (voir la figure 3). L'épaisseur de ladite zone de mélange doit généralement rester inférieure à 15 % de la hauteur de la cellule. Ladite épaisseur est une donnée définie en fonction des caractéristiques géométriques de la cellule telles que :

    • hauteur de la cellule
    • hauteur du volume engendré par le déplacement du pont de levage
    • hauteur occupée par les équipements fonctionnels inclus dans la zone polluée.
    The containment barrier 3 is a mixing zone in the volume of which the temperature gradient along a vertical is very high with respect to that which prevails in the two volumes 4 and 5 outside this zone 3 (see the figure 3). The thickness of said mixing zone must generally remain less than 15% of the height of the cell. Said thickness is a datum defined as a function of the geometric characteristics of the cell such as:
    • cell height
    • height of the volume generated by the movement of the lifting bridge
    • height occupied by the functional equipment included in the polluted area.

    Pour un niveau de perturbation donné des zones (chaude d'une part, froide d'autre part), cette épaisseur est d'autant plus faible que l'écart de température entre zones est plus grand.For a given level of disturbance of the zones (hot on the one hand, cold on the other hand), this thickness is even smaller than the temperature difference between zones is larger.

    Le balayage des volumes inférieur 4 et supérieur 5 est présentement une ventilation (les fluides intervenant sont de l'air chaud à 60°C et de l'air froid à 28°C, voir l'exemple ci-après). A propos de ladite ventilation, on peut préciser ce qui suit:The scanning of the lower 4 and upper 5 volumes is currently a ventilation (the fluids involved are hot air at 60 ° C and cold air at 28 ° C, see example below). About this breakdown, we can specify what following:

    1) Principe général 1) General principle

    La ventilation est conçue comme si elle devait assurer le taux de renouvellement de l'air dans deux cellules distinctes superposées (4 et 5) et séparées par un volume matériel dont l'épaisseur serait celle de la zone de mélange 3. Ces deux cellules virtuelles (ou zones) sont alimentées par un débit d'air ayant subi les traitements habituels de l'air de ventilation des unités de retraitement. The ventilation is designed as if it should ensure the rate of air renewal in two separate superimposed cells (4 and 5) and separated by a material volume whose thickness would be that of the area of mix 3. These two virtual cells (or zones) are supplied with a flow air that has undergone the usual treatment of ventilation air from reprocessing units.

    Les bouches de soufflage A et D sont disposées de telle sorte qu'elles produisent dans chaque zone 5 et 4 respectivement, un écoulement à faible vitesse permanente verticale (quelques cm/s) et dont la composante aléatoire doit être aussi réduite que possible. L'écoulement dans la zone inférieure (froide) 4 est orienté de bas en haut, celui dans la zone supérieure (chaude) 5 de haut en bas.The air outlets A and D are arranged so that they produce in each zone 5 and 4 respectively, a flow at low speed vertical permanent (a few cm / s) and whose random component must be as small as possible. The flow in the lower (cold) zone 4 is oriented from bottom to top, the one in the upper (hot) zone 5 from top to bottom.

    Les fentes de reprise B et C sont situées de part et d'autre de la zone de mélange 3 :

    • les fentes B de reprise d'air chaud sont situées juste au-dessus de l'interface supérieure de ladite zone de mélange 3;
    • les fentes C de reprise d'air froid sont situées juste au-dessous de l'interface inférieure de ladite zone 3.
    The return slots B and C are located on either side of the mixing zone 3:
    • the hot air return slots B are located just above the upper interface of said mixing zone 3;
    • the cold air return slots C are located just below the lower interface of said zone 3.

    Ces fentes de reprise B et C stabilisent le niveau de ladite zone de mélange 3.These return slots B and C stabilize the level of said zone of mixture 3.

    Cette stabilisation exige un contrôle suffisamment précis du rapport des débits de soufflage et d'extraction des circuits d'air chaud et d'air froid, la solution la plus simple à mettre en oeuvre à cet égard étant le recyclage de l'air chaud qui présente par ailleurs l'avantage d'une économie d'énergie thermique associée à une réduction de dimension des batteries de chauffe.This stabilization requires a sufficiently precise control of the ratio of supply and extract air flows from the hot and cold air circuits, the solution the simplest to implement in this regard being the recycling of hot air which also has the advantage of saving thermal energy associated with reduction in size of the heating batteries.

    2) Caractéristiques physiques de l'air, dimensionnantes de la ventilation2) Physical characteristics of the air, dimensioning of the ventilation a) Air de la zone chaude 5 :a) Hot zone air 5: Débit d'alimentationFeed rate

    Compte tenu du fait que cette zone 5 ne contient pas de source de pollution, il faut :

    • d'une part, que la vitesse débitante (orientée selon la verticale descendante) à travers une section droite horizontale voisine du plan supérieur de la zone de mélange 3, soit plus élevée que celles des diffusions browniennes et turbulentes des particules polluantes ayant pénétré dans ladite zone de mélange 3,
    • d'autre part, que le débit d'air chaud soit suffisant pour compenser les pertes par convection avec les parois.
    In view of the fact that this zone 5 does not contain any source of pollution, it is necessary:
    • on the one hand, that the flow velocity (oriented along the descending vertical) through a horizontal cross section close to the upper plane of the mixing zone 3, is higher than that of the Brownian and turbulent diffusions of the polluting particles having penetrated into said mixing zone 3,
    • on the other hand, that the flow of hot air is sufficient to compensate for the losses by convection with the walls.

    Un calorifugeage des parois latérales de la zone supérieure 5, qui réduit les échanges thermiques et les courants de convection parasites, est un élément favorable à la stabilité de la zone de mélange 3.Insulation of the side walls of the upper zone 5, which reduces heat exchange and parasitic convection currents, is an element favorable to the stability of the mixing zone 3.

    Température :Temperature :

    La température dans la zone supérieure 5 doit être la plus élevée possible, elle est seulement limitée par la contrainte de refroidissement des moteurs de l'unité de levage. The temperature in the upper zone 5 must be as high as possible, it is only limited by the cooling constraint of the the lifting unit.

    b) Air de la zone froide 4 :b) Air in cold zone 4: Débit d'alimentation :Feed rate:

    Le débit d'air d'alimentation du volume inférieur 4 est fonction de l'intensité des sources de pollution et de leur nature, et principalement de la puissance totale dégagée par les sources thermiques qu'elle contient; l'échauffement de la température moyenne de l'air qui en résulte devant être compensé par le débit d'air froid.The supply air flow rate of the lower volume 4 is a function of the intensity of the sources of pollution and their nature, and mainly the total power released by the thermal sources it contains; warming of the resulting average air temperature to be compensated for by the cold air flow.

    La contrainte de limitation de l'épaisseur de la couche de mélange 3 (donc de la vitesse de pénétration et de la vitesse débitante ascendante de l'air à travers une section droite horizontale), détermine dans chaque cas la valeur maximale admissible du débit.The constraint of limiting the thickness of the mixture layer 3 (therefore of the speed of penetration and the speed of upward flow of air through a horizontal cross section), determines in each case the maximum value admissible flow.

    Température :Temperature :

    Les basses températures étant un facteur favorable à la diminution de l'épaisseur de la couche de mélange 3 et à sa stabilité (sous réserve qu'elle reste positive), il n'y a pas de limite inférieure à la température de l'air de la zone inférieure. Toutefois, pour des raisons de simplicité et de limitation des investissements, on utilise généralement de l'air à température ambiante. La température prise en compte pour le dimensionnement doit alors être celle correspondant au maximum météorologique enregistré sur le site pendant une période de référence suffisamment longue.Low temperatures being a favorable factor in the reduction of the thickness of the mixture layer 3 and its stability (provided that it remains positive), there is no lower limit for the area air temperature lower. However, for reasons of simplicity and limitation of investments, air is generally used at room temperature. The temperature taken into account for sizing must then be that corresponding maximum meteorological recorded on the site during a period of sufficiently long reference.

    Niveau de turbulence :Turbulence level:

    Plus élevé que dans la zone chaude 5, du fait de la présence des sources thermiques et de la disposition des bouches de soufflage D, il est caractérisé par la valeur maximale de la moyenne quadratique de la vitesse aléatoire à l'interface avec la zone de mélange 3, qui est le paramètre déterminant de la hauteur de ladite zone 3.Higher than in hot zone 5, due to the presence of sources and the arrangement of the air outlets D, it is characterized by the maximum value of the quadratic mean of the random velocity at the interface with the mixing zone 3, which is the determining parameter of the height of said zone 3.

    A propos du dispositif utilisé pour la mise en oeuvre de la ventilation, on peut préciser ce qui suit.About the device used for the implementation of ventilation, we can clarify the following.

    1)1) Alimentation et conception des bouches de ventilationSupply and design of ventilation outlets

    L'équirépartition du débit de soufflage des bouches de ventilation A, D d'une part, et des débits d'extraction des fentes de reprise B, C d'autre part, est un élément indispensable à l'efficacité de la stratification.The equal distribution of the blowing rate of the ventilation outlets A, D on the one hand, and extraction rates of the return slots B, C on the other hand, is a essential for effective stratification.

    Les gaines d'alimentation des bouches de soufflage A, D et les gaines d'extraction des fentes de reprise B, C doivent être conçues en fonction de cette contrainte (aubage des ventilateurs, sections de gaine variables, etc.). De ce fait, et compte tenu de l'encombrement éventuel qui en résulte, l'étude de dimensionnement des gaines est un élément essentiel de la conception du dispositif, étude qui doit précéder celle du génie civil de la cellule.Supply ducts for air outlets A, D and ducts extraction slots B, C must be designed according to this constraint (blading of fans, variable duct sections, etc.). Therefore, and taking into account the possible congestion which results therefrom, the dimensioning study ducts is an essential element in the design of the device, a study which must precede that of the civil engineering of the cell.

    La cellule peut en effet être conçue avec des doubles-parois internes en calorifuge (par exemple en verre expansé) ; l'espace de l'ordre de 0,4 m entre ces parois et celles du génie civil de la cellule étant alors disponible pour les gaines et dispositifs de répartition d'air de soufflage.The cell can indeed be designed with internal double walls in heat-insulating (for example in expanded glass); the space on the order of 0.4 m between these walls and those of the civil engineering of the cell then being available for the sheaths and supply air distribution devices.

    De plus, une répartition uniforme des vitesses à la section de sortie des bouches de soufflage A, D est nécessaire cette répartition peut être obtenue en garnissant leur orifice de sortie de deux ou trois couches de tôle perforée d'une transparence de l'ordre de 20%, séparées par une distance de quelques centimètres.In addition, a uniform distribution of speeds at the outlet section of the air outlets A, D is necessary this distribution can be obtained by lining their outlet with two or three layers of perforated sheet metal transparency of around 20%, separated by a distance of a few centimeters.

    D'une façon générale, les bouches de soufflage A, D qui sont plus "inductives" (c'est-à-dire qui induisent des mouvements de circulation interne) doivent être le plus éloignées possible de la zone de mélange 3, alors que les fentes de reprise B, C dont l'effet d'induction sur l'environnement est très limité dans l'espace peuvent être situées au plus près de la zone de mélange 3 dont elles bornent et stabilisent les limites sur les parois verticales de la cellule.Generally, the air outlets A, D which are more "inductive" (that is to say which induce internal circulation movements) should be as far away from mixing zone 3 as possible, while the return slots B, C whose induction effect on the environment is very limited in space can be located as close as possible to mixing zone 3 of which they limit and stabilize the limits on the vertical walls of the cell.

    2) Bouches (fentes) de soufflage A d'air chaud (voir figures 2 et 4)2) Hot air supply vents (slots) (see Figures 2 and 4) a) Dispositions générales :a) General provisions:

    Leur disposition doit être telle qu'elle permette de répartir le débit d'air chaud dans les sections horizontales voisines de la zone de mélangé 3, afin que l'écoulement se rapproché au mieux d'un flux laminaire.Their arrangement must be such as to allow the air flow to be distributed hot in the horizontal sections adjacent to the mixed zone 3, so that the flow is as close as possible to a laminar flow.

    Pour satisfaire ces conditions, les bouches de soufflage peuvent être disposées (en tenant compte du mode de fixation de l'unité de levage) suivant des fentes de faible largeur, parallèles à l'axe longitudinal de la cellule et pratiquement continues.To satisfy these conditions, the air outlets can be arranged (taking into account the method of fixing the lifting unit) according to narrow slots, parallel to the longitudinal axis of the cell and practically continuous.

    Leur vitesse d'émission, qui détermine leur section minimale en fonction du débit recherché, doit être telle que les vitesses maximales d'impaction sur les éléments constitutifs du pont de levage 2 soient au plus égales à 0,4 m/s. On évite ainsi la génération de turbulences nuisibles à la stabilité de la zone de mélange 3.Their transmission speed, which determines their minimum cross-section depending on of the desired flow rate, must be such that the maximum impact velocities on the constituent elements of the lifting bridge 2 are at most equal to 0.4 m / s. We avoid thus the generation of turbulence detrimental to the stability of the mixing zone 3.

    b) Débit d'air chaud :b) Hot air flow:

    Le débit d'air chaud est choisi afin d'assurer une vitesse débitante de l'ordre de 0,04 m/s à travers l'aire de la section horizontale du volume supérieur 5. En effet, compte tenu de la vitesse de soufflage et de la répartition adoptée pour les bouches d'alimentation de la zone supérieure 5, l'écoulement à proximité du plan supérieur de la zone de mélange 3 peut être assimilé à un flux laminaire où la diffusion turbulente est négligeable, et, pour les plus fines particules polluantes (dont la diffusion est la plus rapide), la vitesse de diffusion brownienne est très inférieure à 0,04 m/s.The hot air flow is chosen to ensure a flow rate of about 0.04 m / s across the area of the horizontal section of the upper volume 5. In fact, taking into account the blowing speed and the distribution adopted for the supply outlets of the upper zone 5, the flow near the upper plane of mixing zone 3 can be likened to a laminar flow where the turbulent diffusion is negligible, and, for the finest polluting particles (whose diffusion is the fastest), the Brownian diffusion speed is very less than 0.04 m / s.

    3) Bouches (fentes) de soufflage D d'air froid (voir figures 2, 4, 5 et 6) 3) Cold air supply vents (slots) D (see figures 2, 4, 5 and 6) a) Dispositions générales :a) General provisions:

    La disposition et la géométrie des bouches d'émission d'air froid D ont pour objet d'homogénéiser au mieux la concentration en air pollué et en air chaud dans l'ambiance de la zone inférieure (zone froide) 4, tout en limitant la composante verticale des vitesses aléatoires de la turbulence induite.The arrangement and geometry of the cold air emission outlets D have for the purpose of optimizing the concentration of polluted air and hot air in the atmosphere of the lower zone (cold zone) 4, while limiting the component vertical of the random velocities of the induced turbulence.

    Les bouches d'émission D de faible largeur (en forme de meurtrières) sont situées à proximité du plancher sur les côtés les plus longs de la cellule et disposées en quinconce.The narrow D emission outlets (in the form of loopholes) are located near the floor on the longest sides of the cell and arranged in staggered rows.

    Cette disposition produit des jets 10 d'air à plan axial vertical emboítés les uns dans les autres (voir figure 6).This arrangement produces jets 10 of air with a vertical axial plane nested one inside the other (see Figure 6).

    Ces jets-plans produisent, par l'effet de cisaillement dû aux vitesses opposées, des tourbillons dont les vitesses ont de faibles composantes verticales et qui provoquent le mélange avec l'ambiance des courants issus des diverses sources (voir figure 5).These jet planes produce, by the shearing effect due to the velocities opposite, vortices whose velocities have small vertical components and which cause the currents from various sources to mix with the atmosphere (see figure 5).

    En effet, d'une part on constate que les tourbillons à axe horizontal, générateurs de vitesses aléatoires verticales, sont produits à partir d'une surface très réduite (celle d'une "meurtrière") par rapport à celle de l'interface entre jets 10. D'autre part, on voit que le différentiel de vitesse entre les jets 10 dans leur partie supérieure et l'ambiance quasi immobile de la cellule est deux fois plus faible que le différentiel de vitesse qui règne entre jets opposés, ce qui génère des courants horizontaux largement prédominants par rapport aux courants verticaux dirigés vers le haut. Pour ces deux raisons, la composante verticale des vitesses aléatoires se trouve sensiblement atténuée, et les phénomènes de pénétration dans la couche de mélange se trouvent ainsi limités ; de plus, cette disposition tend à "casser" par dilution la vitesse ascendante des courants issus des sources thermiques qui est le facteur le plus important de pénétration éventuelle de la pollution dans la zone protégée 5.On the one hand, we see that vortices with a horizontal axis, vertical random speed generators, are produced from a surface very reduced (that of a "loophole") compared to that of the interface between jets 10. On the other hand, we see that the speed differential between the jets 10 in their part superior and the almost immobile atmosphere of the cell is half as low as the speed differential between opposing jets, which generates currents predominantly horizontal compared to directed vertical currents to the top. For these two reasons, the vertical component of the random velocities is significantly attenuated, and the phenomena of penetration into the layer mixing are thus limited; moreover, this provision tends to "break" by dilution the ascending speed of the currents coming from the thermal sources which is the most important factor of possible pollution penetration in the area protected 5.

    b) Débit d'air froidb) Cold air flow

    La valeur de la vitesse moyenne ascensionnelle de l'air est choisie de l'ordre de 0,04 m/s pour limiter l'entraínement des particules polluantes par l'air de ventilation de la zone inférieure 4 à celles dont le "diamètre aérodynamique" est inférieur à 35 µm. Les particules d'un diamètre supérieur ayant tendance à décanter dans la cellule sont peu adhérentes aux parois et relèvent du dépoussiérage par aspiration.The value of the average ascent speed of the air is chosen from about 0.04 m / s to limit the entrainment of polluting particles by the air of ventilation of the lower zone 4 to those whose "aerodynamic diameter" is less than 35 µm. Particles with a larger diameter tend to decant in the cell are not very adherent to the walls and fall under the dust removal by aspiration.

    Cette vitesse définit un débit fonction de l'aire de la section horizontale de la cellule qui doit être par ailleurs suffisant pour assurer, compte tenu de la température d'alimentation de l'air froid et de la puissance des sources chaudes 1, le maintien d'une température suffisamment basse dans la zone froide 4. Dans certaines applications où la puissance thermique moyenne que dégagent les sources chaudes par unité de volume de la cellule est très élevée, une batterie de refroidissement de l'air d'alimentation peut être nécessaire pour limiter son débit. Dans ce cas particulier, l'utilisation d'une pompe à chaleur élevant la température de l'air chaud en abaissant celle de l'air froid peut être la solution la plus rationnelle.This speed defines a flow depending on the area of the horizontal section of the cell which must also be sufficient to ensure, taking into account the cold air supply temperature and hot spring power 1, maintaining a sufficiently low temperature in the cold zone 4. In some applications where the average thermal power emitted by the sources per unit volume of the cell is very high, a cooling battery supply air may be required to limit its flow. In this special case, the use of a heat pump raising the air temperature warm by lowering that of cold air may be the most rational solution.

    4) Fentes de reprise B, C (air froid C et air chaud B) 4) Return slots B, C (cold air C and hot air B)

    Les fentes de reprise d'air froid C et d'air chaud B sont disposées en lignes horizontales constituant des fentes pratiquement continues (intervalles entre côtés verticaux des bouches d'aspiration aussi réduits que possible), ces lignes horizontales se faisant vis-à-vis sur les deux côtés les plus longs.The cold air C and hot air B return slots are arranged in horizontal lines constituting practically continuous slits (intervals between vertical sides of the suction outlets as small as possible), these lines horizontal facing each other on the two longest sides.

    Le niveau supérieur des fentes de reprise d'air froid C limite le plan inférieur de la zone de mélange 3, alors que le niveau inférieur des fentes de reprise d'air chaud B limite le plan supérieur de ladite zone de mélange 3. Le niveau supérieur des fentes de reprise d'air chaud B doit être situé à environ 1 m au-dessous du niveau inférieur du volume dans lequel évolue l'unité de levage. Dans le cas de l'existence d'un garage-pont, le niveau supérieur des fentes de reprise d'air chaud doit se situer au-dessous du niveau du plancher dudit garage-pont.The upper level of the cold air return slots C limits the plane of the mixing zone 3, while the lower level of the hot air intake B limits the upper plane of said mixing zone 3. The upper level of the hot air return slots B must be located approximately 1 m below the lower level of the volume in which the lifting unit operates. In the case of a bridge garage, the upper level of the slots hot air return must be below the level of the floor of the garage.

    En référence à la figure 3, on peut préciser ce qui suit.With reference to FIG. 3, the following can be specified.

    On observe un léger gradient de température dans le volume inférieur, du fait de la présence de la source polluante, chaude ; on observe, par contre, le fort gradient thermique souhaité dans la zone de mélange 3 constituant la barrière de confinement (virtuelle).There is a slight temperature gradient in the lower volume, from made of the presence of the polluting source, hot; we observe, on the other hand, the fort desired thermal gradient in the mixing zone 3 constituting the barrier of confinement (virtual).

    En référence à la figure 4, on précise que pour des raisons de simplification, le pont de levage 2 n'a pas été représenté.Referring to FIG. 4, it is specified that for reasons of simplification, the lifting bridge 2 has not been shown.

    Lé procédé de l'invention a été mis en oeuvre dans la cellule de vitrification dont les dimensions ont été précisées ci-dessus, avec le dispositif décrit ci-dessus et schématisé sur les figures 2, 4 à 6 annexées. On précise dans le tableau ci-après les caractéristiques desdits procédés et dispositifs. Caractéristiques Air froid Air chaud Température de soufflage 28°C 60°C Débit de soufflage 5 300 Nm3/h 5 100 Nm3/h Température zone 4   48°C 5   60°C Débit massique air 1,9 kg/s 1,8 kg/s Largeur des bouches de soufflage D   0,19m A   0,18 m Longueur des bouches de soufflage D   0,81 m (pour obtenir des jets-plans verticaux) A   12,0 m = longueur de la cellule Distance horizontale entre deux bouches de soufflage D   1,12 m A   en fonction de l'encombrement du pont de levage Nombre total des bouches de soufflage D   16 (8 "meurtrières" réparties en quinconce sur chacune des deux grandes faces verticales de la cellule) A   deux fentes parallèles, au plafond de la cellule Disposition des bouches de soufflage D   Verticales A   Horizontales Positionnement des bouches de soufflage D   Rebord inférieur à proximité du niveau du plancher de la cellule A   Dans le sens de la plus grande longueur Nombre de fentes de reprise C   2 (1 fente sur chaque grande face verticale) B   2 (1 fente sur chaque grande face verticale) Disposition des fentes de reprise C Horizontales B   Horizontales Positionnement des fentes de reprise C   à 4,5 m au-dessus du plancher de la cellule, à là limite inférieure de la zone de mélange B   à 5,8 m au-dessus du plancher de la cellule, à la limite supérieure de la zone de mélange Largeur des fentes de reprise C   0,2 m B   0,2 m Longueur des fentes de reprise C   = longueur de la cellule = 12,0 m B   = longueur de la cellule=12,0m The process of the invention has been implemented in the vitrification cell, the dimensions of which have been specified above, with the device described above and shown diagrammatically in Figures 2, 4 to 6 attached. The characteristics of said methods and devices are specified in the table below. Characteristics Cold air Hot air Supply temperature 28 ° C 60 ° C Blowing flow 5,300 Nm 3 / h 5 100 Nm 3 / h Zone temperature 4 48 ° C 5 60 ° C Air mass flow 1.9 kg / s 1.8 kg / s Width of the air outlets D 0.19m 0.18 m Length of air outlets D 0.81 m (for vertical jets) At 12.0 m = cell length Horizontal distance between two air outlets D 1.12 m A depending on the size of the lifting bridge Total number of air outlets D 16 (8 "loopholes" staggered on each of the two large vertical faces of the cell) Has two parallel slits on the cell ceiling Arrangement of air outlets D Verticals A Horizontal Positioning of the air outlets D Lower edge near the floor level of the cubicle A In the direction of the greatest length Number of return slots C 2 (1 slot on each large vertical face) B 2 (1 slot on each large vertical face) Layout of the return slots C Horizontal B Horizontal Positioning of the return slots C 4.5 m above the cell floor, at the lower limit of the mixing zone B 5.8 m above the cell floor, at the upper limit of the mixing zone Width of the return slots C 0.2 m B 0.2 m Length of return slots C = cell length = 12.0 m B = cell length = 12.0m

    Claims (14)

    1. A method of confining pollution generated in the top volume (5) and/or in the bottom volume (4) of an enclosure filled with a fluid, i.e. either a gas, which is in general air, or a liquid, which is in general water, characterized in that it comprises the creation of a virtual confinement barrier in maintaining the mean temperature of said top volume (5) higher than the mean temperature of said bottom volume (4) by an amount that is sufficient to ensure that said two volumes (5, 4) are separated by a turbulent intermediate zone (3) of narrow width, referred to as the "mixing zone", within which a steep temperature gradient is maintained; said intermediate zone (3) constituting said virtual confinement barrier in a horizontal plane and the confinement being so based on the natural phenomenon of thermal stratification.
    2. The method according to claim 1, characterized in that said top volume (5) and said bottom volume (4) are swept independently with fluid injected at respective suitable temperatures; the fluid injected into the top volume (5) being extracted therefrom immediately above the top interface of said mixing zone (3), and the fluid injected into the bottom volume (4) being extracted therefrom immediately below the bottom interface of said mixing zone (3) ; said fluids being either identical or different, and being injected into the respective volumes (5, 4) under conditions that minimize the vertical component of the speed of the turbulence that is generated.
    3. The method according to claim 2, characterized in that the hot fluid sweeping the top volume (5) is recycled, at least in part.
    4. The method according to any one of claims 1 to 3, characterized in that it is implemented in an enclosure filled with gas, which is in general air, to confine pollution given off by a possibly hot pollution source (1) disposed at the bottom of the enclosure; said enclosure being, in particular, constituted by a cell for vitrifying fission products in the nuclear industry.
    5. An apparatus for confining pollution generated in the top volume (5) and/or in the bottom volume (4) of an enclosure filled with a fluid, i.e. either a gas, which is in general air, or a liquid, which is general water, characterized in that it comprises:
      (a) temperature-maintaining means for maintaining the mean temperature of said top volume (5) greater than the mean temperature of said bottom volume (4) by creating a virtual confinement barrier in a horizontal plane between said top volume (5) and said bottom volume (4), said virtual confinement barrier being constituted by a narrow, turbulent intermediate zone (3) referred to as the "mixing zone", within which a steep temperature gradient is maintained;
      and advantageously
      (b) means for thermally-insulating at least some of the walls of said top volume (5).
    6. The apparatus according to claim 5, characterized in that said temperature-maintaining means (a), which comprise fluid delivery apparatus (A and D) and fluid extraction apparatus (B and C), suitably disposed in each of said top (5) and bottom (4) volumes, ensure that each of said top (5) and bottom (4) volumes is swept with said fluid, at a respective suitable temperature; said delivery means (A and D) being of shape and size optimized to reduce the vertical component of the speed of the generated turbulence.
    7. The apparatus according to claim 6, characterized in that said extraction apparatus (B) for extracting the hot fluid from the top volume (5), and said extraction apparatus (C) for extracting the cold fluid from the bottom volume (4) consist of narrow slots distributed uniformly on respective common levels and facing one another along the entire length of two opposite vertical walls of the enclosure.
    8. The apparatus according to one of claims 6 or 7, characterized in that said delivery apparatus for delivering the hot fluid (A) into the top volume (5) and/or said delivery apparatus (D) for delivering the cold fluid into the bottom volume (4) consists of respective horizontal surfaces ensuring that said fluid is distributed continuously.
    9. The apparatus according to one of claims 6 or 7, characterized in that said delivery apparatus for delivering the hot fluid (A) into the top volume (5) and/or said delivery apparatus for delivering the cold fluid (D) into the bottom volume (4) consists of at least two narrow slots distributed uniformly and parallel over the entire length of a horizontal wall (generally the ceiling and/or the floor) of the enclosure.
    10. The apparatus according to one of claims 6 or 7, characterized in that said delivery apparatus for delivering the hot fluid (A) into the top volume (5) or(and) said delivery apparatus for delivering the cold fluid (D) into the bottom volume (4), consists of two respective series of slots of narrow width and of small height distributed uniformly in staggered manner over the entire length of two opposite vertical walls of the enclosure; said slots starting at or in the vicinities of the horizontal wall, generally the ceiling or the floor (of the horizontal walls, generally the ceiling and the floor) in contact with said vertical walls.
    11. The apparatus according to one of claims 6 or 7, characterized in that, in the volume(s) in which the pollution is generated, namely the top volume (5) or(and) the bottom (4) volume, the fluid delivery apparatus (A and/or D) consists of two series of slots, of narrow width and of small height, distributed uniformly in staggered manner over the entire length of two opposite vertical walls of the enclosure; said slots starting at or in the vicinities of the horizontal wall, generally the ceiling or the floor (of the horizontal walls, generally the ceiling and the floor) in contact with said two vertical walls.
    12. The apparatus according to any one of claims 6 to 11, characterized in that it further comprises means for recycling, at least in part, the hot fluid sweeping the top volume (5).
    13. The apparatus according to any one of claims 6 to 12, characterized in that it said cold fluid delivery apparatus (D) is fed with fluid at ambient temperature or with fluid cooled upstream, advantageously by means of a heat pump that uses the heat energy taken from said fluid to raise the temperature of the fluid fed to the hot fluid delivery apparatus (A).
    14. The apparatus according to claim 6, useful for confining pollution given off by a possibly hot pollution source (1) disposed at the bottom of an enclosure filled with a gas, which is in general air, characterized in that it comprises:
      in its bottom volume (4), delivery apparatus for delivering a cold gas (D), in general air, and consisting of two series of slots, of narrow width and of small height, distributed uniformly in staggered manner over the entire length of two opposite vertical walls of the enclosure; said slots starting at or in the vicinities of the horizontal wall, generally the floor, in contact with said two vertical walls;
      in its top volume (5), delivery apparatus for delivering a hot gas (A), in general air, and consisting of at least two slots, of narrow width, distributed uniformly and parallel over the entire length of a horizontal wall, generally the ceiling, of the enclosure; and
      in each of its top (5) and bottom (4) volumes, extraction apparatus (B, C), for extracting the injected gas, in general air, and consisting of slots, of narrow width, distributed uniformly at the same level and facing one another over the entire length of two opposite vertical walls of the enclosure.
    EP98402641A 1997-10-24 1998-10-23 Process and device for confinement using thermal stratification Expired - Lifetime EP0911588B1 (en)

    Applications Claiming Priority (2)

    Application Number Priority Date Filing Date Title
    FR9713338A FR2770330B1 (en) 1997-10-24 1997-10-24 METHOD AND DEVICE FOR CONTAINMENT BY THERMAL LAMINATION
    FR9713338 1997-10-24

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    EP0911588A1 EP0911588A1 (en) 1999-04-28
    EP0911588B1 true EP0911588B1 (en) 2003-10-01

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    GB2379549A (en) 2001-09-06 2003-03-12 Sharp Kk Active matrix display
    US7190887B1 (en) * 2005-03-28 2007-03-13 Compton Stephan S Portable thermal-stratifying space heater and powerplant package
    CA2691245C (en) * 2009-01-28 2018-09-25 Bryn Gough Magee Enhanced entranceway
    CA2789747C (en) * 2010-02-15 2017-06-13 Koken Ltd. Local clean zone forming apparatus
    US9435554B2 (en) * 2012-02-17 2016-09-06 Athletic Recovery Zone, Llc Outdoor heating or cooling seating system
    CN102842346B (en) * 2012-08-27 2015-02-25 华北电力大学 System for processing serious accidents caused by helium pressurization in nuclear power plant
    CN103337269B (en) * 2013-07-05 2015-07-29 中国原子能科学研究院 A kind of glove box for dry method aftertreatment
    CN112668257A (en) * 2021-01-25 2021-04-16 东莞市万科建筑技术研究有限公司 Multi-heat-source-based building indoor natural ventilation design method

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    DE2305101A1 (en) * 1973-02-02 1974-08-08 Buettner Schilde Haas Ag SHIELDING A ROOM BY AN AIR CURTAIN
    US4390008A (en) * 1980-06-26 1983-06-28 The United Stated Of America As Represented By The Department Of Energy Hot water tank for use with a combination of solar energy and heat-pump desuperheating
    FR2530163B1 (en) * 1982-07-15 1986-08-29 Commissariat Energie Atomique METHOD FOR CONTAINING THE POLLUTION OF A PREMISES USING A GAS VEIN
    US5078574A (en) * 1990-11-19 1992-01-07 Olsen George D Device for minimizing room temperature gradients
    FR2730297B1 (en) * 1995-02-02 1997-05-09 Soc Generale Pour Les Techniques Nouvelles Sgn CONTAINMENT METHOD AND DEVICE, ESPECIALLY OF A PARTICULAR ATMOSPHERE IN A CONTINUOUS PROCESSING SPACE OF THROUGHPUT PRODUCTS

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    FR2770330B1 (en) 2000-01-14
    DE69818604T2 (en) 2004-07-08
    US6386968B2 (en) 2002-05-14
    JPH11218598A (en) 1999-08-10
    EP0911588A1 (en) 1999-04-28
    FR2770330A1 (en) 1999-04-30
    DE69818604D1 (en) 2003-11-06
    US20020000525A1 (en) 2002-01-03
    JP4272281B2 (en) 2009-06-03

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