EP0942244B1 - Isothermal container - Google Patents

Description

The invention relates to the field of isothermal containers comprising, above a storage compartment, a cryogenic compartment for the storage of dry ice ensuring the conservation of fresh or frozen products. A container according to the preamble of claim 1 is for example known from the document EP-A-0 823 600.

It relates more particularly to the compartments cryogenic whose front face is equipped with at least one opening connectable to the injector of a dioxide injection device carbon in liquid phase, and at least one opening which can be connected to a suction source to recover carbon dioxide, during snow formation.

In general, to allow cleaning of the compartment cryogenic, this consists of a removable tray or a drawer, this tray or drawer being slidably mounted in slides arranged in the inner wall of the container.

When loading the cryogenic compartment, the pressure carbon dioxide injection in the liquid phase is around 15 to 25 bars. To prevent this pressure from damaging the compartment, it is known, for example from French patent application 2,706,990, from make the metal tray and have one or more walls in it deflectors that reduce the violence of the carbon dioxide jets by liquid phase coming out of injection nozzles arranged in the compartment. Such a solution is expensive and is not applicable to containers isothermal synthetic material, more suitable for the conservation of fresh products, because they do not require an additional insulating screen for limit the cold radiation generated by the bottom of a metal container.

French patent applications 2,751,623 and 2,752,049, to name of the applicant, describe such bins or drawers fitted with a tablecloth dry ice retention. This tablecloth, which is porous with gas and no to dry ice, is reinforced by a metallic mesh. The injection is carried out using external equipment, the only one injector is arranged in the front opening of the compartment. During injection of carbon dioxide in the liquid phase, and independently of forces communicated to the walls and the sheet, the wear of which is fairly fast, the jet disturbs the formation of carbon dioxide snow which collects locally and does not spread over the entire bottom of the tank. This reduces the exchange surface with the storage compartment and therefore modifies storage conditions.

The object of the present invention is to remedy this disadvantage by providing an insulated container comprising a jet breaker device for a tray or drawer cryogenic compartment supplied by an external nozzle, reducing the effects of pressure on the tank and abrasion on the retention wall snow, but also improving snow filling.

To this end, in the container according to the invention, the jet breaker is consisting of a tubular mesh of pressure-resistant material which, arranged in the snow storage chamber, is an extension of the opening for the injector of an injection device, is linked to the wall front of this drawer by one of its ends, is closed at its other end and comprises, at least in part of its wall, meshes, forming a regular lacunar network letting pass the gas but also the snow forming inside the trellis.

So when injecting carbon dioxide in the liquid phase in the cryogenic compartment, the jet pressure is absorbed by the tubular mesh, so that the forces perceived by the walls are considerably reduced. Under the effect of expansion, carbon dioxide liquid is transformed, inside the jet breaker, into carbon dioxide snow which, under the effect of the residual pressure, passes through the free passages of the tubular mesh and is distributed evenly over the bottom of the compartment.

Advantageously, the ratio S1 / S2 between the perforated surface S1 and the surface S2 of the part allowing the snow to pass through the tubular trellis is between 0.45 and 0.8.

Indeed, it turned out that a vacuum area S1 / area ratio full S2 less than 0.45 resulted in yield losses in the carbon dioxide snow formation.

In one embodiment, the tubular trellis is provided with mesh over its entire periphery and has, on its upper part and on its entire length, a semi-cylindrical mesh cover corresponding.

This hood opposes the exit of the snow upwards, in direction of the porous sheet of gas and therefore opposes its clogging by snow, which guarantees gas evacuation. It also promotes snow distribution over the entire bottom of the cryogenic compartment.

Figure 1 est une vue en perspective de l'ensemble du bac tiroir,

Figure 2 en est une vue en coupe longitudinale, lorsqu'il est mis en place dans un conteneur isothermique et lors de la phase d'injection,

Figure 3 est une vue en coupe transversale suivant III-III de figure 2,

Figure 4 est une vue en coupe suivant IV-IV de figure 2 montrant, à échelle agrandie, la section transversale du corps tubulaire du brise-jet.

Other advantages will emerge from the description which follows with reference to the appended schematic drawing representing an embodiment of the jet-breaking device in the case of its application to a container equipped with a drawer.

FIG. 1 is a perspective view of the entire drawer,

FIG. 2 is a view in longitudinal section thereof, when it is placed in an isothermal container and during the injection phase,

FIG. 3 is a cross-sectional view along III-III of FIG. 2,

Figure 4 is a sectional view along IV-IV of Figure 2 showing, on an enlarged scale, the cross section of the tubular body of the jet breaker.

In this drawing, the reference numeral 2 denotes, so general, an isothermal container 2 with a front door 3 and whose cavity internal is provided with slides, respectively lateral 4 and posterior 5, in which the edges, respectively lateral and posterior, from the bottom 6 of a drawer 7. This drawer divides the internal cavity of the container in an upper cryogenic compartment A and a compartment lower B for storage of fresh or frozen products.

In the embodiment shown, the drawer 7 has a front wall 8, capable of being fitted into an appropriate rebate of the container, and its bottom 6 is integral with a parallelepipedic tank 9 in form of box open upwards and whose upper opening is closed by a sheet 10, porous to gas but not to dry ice.

The drawer is, for example, made by rotational molding of polyethylene and its hollow walls are filled with an insulating material, such as than polyurethane foam 12.

The tank 9, whose internal cavity constitutes the chamber C of storage of dry ice, is less high and less wide than the compartment A in which it is arranged, so as to provide in this compartment a gas accumulation chamber D during the phase injection of carbon dioxide, but also during the sublimation of the dry ice during storage. Room C communicates with the exterior by an opening 14, visible in FIG. 1, formed in the wall front 8 of the drawer. As for the gas accumulation chamber D, it communicates with the outside through an opening 15, formed in the same wall 8.

These two openings can be closed either with a plug or simply by seals 16 carried by the front door 3 and coming in support on the wall 8, when the door is closed.

According to the invention, the tank 9 is equipped with a jet breaker 20 which is consisting of a tubular mesh 21 made of pressure-resistant material, extending longitudinally inside the tank. Its anterior end is fixed on the internal face of the front wall 8, in the extension of the opening 14, for example by a flange 22. The other end of the jet breaker is closed and shaped as lug 23. This is fixed by a screw transverse not shown, on a step 24 projecting from the bottom of the tank and disposed near the rear wall 6a of this tank. Leg 23 is advantageously formed by flattening the tubular mesh in one of its diametrical plans.

This tubular mesh is crossed by meshes 25. According to embodiments, and depending on the injection pressures used, there may consist of metallic fabric, metallic fabric, metal deployed or by a perforated sheet.

According to an essential characteristic of a particular embodiment of the invention, the perforations 25 are distributed in the part of the tubular mesh 21 which makes opposite the bottom 6 of the tank, that is to say over substantially its half lower, which implies that its upper part has no perforations.

In the embodiment shown in Figure 4, the trellis tubular 21 is constituted by a metallic fabric, bent to form a sleeve whose longitudinal edges are connected by a few points of solder 26. The upper part of the body, thus obtained, is covered by a semi-cylindrical cover 27, formed by a metal sheet which, after putting in shape, is fixed to the canvas by welds 28. The metallic canvas is also welded to the flange 22, so as to form an assembly monolithic with this flange.

The S1 / S2 ratio between, respectively, the total area perforated S1 of the meshes 25 used and the surface S2 of the cylindrical part tubular mesh allowing snow to pass, is between 0.45 and 0.8, and that whatever the dimension of the meshes which is defined according mechanical strength of the jet breaker.

When the tank is filled with a device 17, distributing by an injector 18, a metered amount of dioxide carbon in liquid phase, the pressurized jet emitted by the injector 18 remaining outside the jetbreaker is distributed longitudinally inside the body tubular of the breakwater 20 where it immediately turns into snow and gas. Due to its rigid structure, the jet breaker absorbs without deformation the forces resulting from this projection, and already reduced by the relaxation immediate. Furthermore, the non-perforated part, constituted by the cover 27, opposes any upward projection, in the direction of the sheet 10, and therefore prevents it, which is more fragile, from being subjected to accelerating forces its wear by abrasion.

Under the effect of the pressure, the snow crosses the meshes 25 of the jet breaker and is distributed evenly over the bottom of the tank, as shown in 31 in FIG. 3. Only a zone 32, placed immediately under the jet breaker does not have snow, since it is driven by the breath of snow and gas passing through the jet breaker but the surface as well neglected is insignificant compared to the total surface of the tank in which the snow distributes evenly. By snow accumulation effect spreads over the jet breaker.

During the injection, the gas escapes from the tank through the sheet 10, as shown in arrow 33, and from there goes to room D where it is sucked by means connected to the opening 15 formed in the wall end.

• Poids 200g / m²
• Epaisseur 15 mm
• Classification G3
• Rendement gravimétrique 85%
• Rendement opacimétrie moins de 20 %
• Capacité de colmatage 600 g / m²

As an example of embodiment, the conditions for filling a drawer comprising a parallelepipedal container having the internal dimensions 407 x 533 x 90 mm and a capacity of 19.5 dm3 and in which the jet breaker, having a diameter of 35 mm and a length of 530 mm, was produced in a metallic fabric having 1.5 mm square meshes formed by wires whose thickness was 0.5 mm. The sheet 10 disposed above the opening of the tank was constituted by a filter medium made of thermally bonded polypropylene fibers and resistant to humidity. The characteristics of this tablecloth were as follows:

• Weight 200g / m ²
• Thickness 15 mm
• G3 classification
• Gravimetric efficiency 85%
• Opacimetry yield less than 20%
• Clogging capacity 600 g / m ²

The injection of carbon dioxide in liquid phase under a pressure of 21 Bars, with a flow rate of 19.2 Kg / min for 30 seconds produces 4.3 Kilograms of snow, giving a yield of 44.79%.

Various tests have shown that this yield varied between 42 and 46% depending on the flow rate and injection pressure of the dioxide carbon in the liquid phase, characteristics of the sheet 10 and temperature conditions of the filling line and tank.

Because of its simplicity, the jet breaker is inexpensive and its low cost is more than made up for by longer service life of the drawer, since, during repeated injections, its resistance is not affected and therefore can be used safely for many fillings. In some applications, for example when it is very away from the sheet 10, the jet breaker is porous to snow over its whole periphery. In addition, it can be juxtaposed with another jet breaker, arranged in the same bin or in a neighboring bin.

Claims (5)

1. Isothermal container comprising a cryogenic compartment (A) consisting of a drawer (7) mounted in a detachable manner in the slides of the container and including inside it a cloth (10) that is porous to gas and separating at least one chamber (C) for storing snow and a chamber (D) for accumulating gas, the front wall (8) of the drawer being provided with at least one opening (14) that can be closed and can be connected to the outer injector of an apparatus for injecting carbon dioxide in the liquid phase, and at least one opening (15) that can be closed and can be connected to a source for aspirating gas, characterized in that the cryogenic compartment includes an anti-splash device consisting of a tubular lattice (21), made of a pressure-resistant material which, positioned in the chamber (C) for storing snow, is in the extension of the opening (14) for the outer injector of the injection apparatus, is connected to the front wall (8) of the drawer (7) by one of its ends, is closed at its other end and includes, at least in part of its wall, meshes (25) forming a open-work network allowing gas to pass, but also snow forming inside the tubular lattice.
2. Container according to claim 1, characterized in that the tubular lattice (21) is provided with meshes (25) over all its periphery and includes, on its upper part and over all its length, a semi-cylindrical cap (27) for closing the corresponding meshes.
3. Container according to claim 1, characterized in that the front end of the tubular mesh (21) is secured to a circular flange (22) for attachment against the inner face of the front wall (8) of the tray (7), while its other end is secured to a lug (23) for attachment to a step (24) projecting from the bottom (6) of this tray.
4. Container according to all the claims 1 to 3, characterized in that the fixing lug (23) is formed by flattening the end of the tubular lattice (21).
5. Container according to claim 1, characterized in that the ratio S1/S2 between the perforated surface (S1) and the surface (S2) of the part of the tubular lattice that allows snow to pass is between 0.45 and 0.8.

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