EP0183594B1 - Device for the distribution of a cryogenic liquid - Google Patents

Abstract

This device, which is in particular intended to inject liquid nitrogen in preserving cans so as to pressurize them, comprises an inverted cryogenic container (1,2) having a neck (3) closed by a detachable plate (10). All the elements (11,12,14,19,21) for operating the device extend through this plate in a sealed manner. The pouring conduit (14) has a calibrated orifice (17) mounted in the plate (10) and, above the latter, an electrically-operated valve immersed in the liquid. Application in the packing of flat beverages in metal cans.

Description

• - un récipient cryogénique à double paroi qui, dans sa position d'utilisation, est inversé et comporte d'une part un réservoir intérieur et une enveloppe extérieure présentant chacun une ouverture à leur extrémité inférieure, et d'autre part un col reliant les deux ouvertures, et
• - une conduite d'amenée de liquide cryogénique, une conduite d'évent et une conduite de déversement.

The present invention relates to a device for dispensing a cryogenic liquid, of the type comprising:

• - a double-walled cryogenic container which, in its position of use, is inverted and comprises on the one hand an internal reservoir and an external envelope each having an opening at their lower end, and on the other hand a neck connecting the two openings, and
• - a cryogenic liquid supply line, a vent line and a discharge line.

The invention is intended in particular to provide a continuous stream of liquid nitrogen to a succession of cans scrolling on a conveyor, just before they are closed by crimping.

The manufacturers of containers, in particular of metal cans for consumer liquids such as beverages, have been led, for reasons of cost price, to use thicknesses of material, in particular of metal, which are increasingly reduced. This results in a reduction in the mechanical strength of these containers and a danger of crushing when stacked on top of each other. If the containers containing a product giving off a gas by itself, for example a carbonated drink, resist crushing relatively well, it is not the same for the containers containing a non-gaseous liquid, for example a flat drink such as mineral water, fruit juice, etc. In addition, when these products (fruit juice for example) are sterilized and packaged hot, their contraction on cooling risks deforming the box. In these cases, the containers are artificially pressurized, before the lid is crimped, by the introduction of a few drops of liquefied gas, generally nitrogen, which makes it possible to solve the problem of crushing.

When this technique is applied to high-speed packaging machines, that is to say capable of filling 30,000 to 120,000 containers per hour arranged in a single line, there can be no question of interrupting the flow of liquid nitrogen between successive containers; it is therefore preferable to let a continuous stream of liquid nitrogen flow and allow a small loss of liquid between the successive containers which pass at high speed under the orifice for discharging this liquid.

EP-A-109134 describes a dispensing device of the aforementioned type. However, the structure of this device is complicated, in particular due to the arrangement of the pipes and the presence of a rotary metering disc, which moreover does not make it possible to obtain a continuous flow.

The invention aims to provide a reliable device whose production, use and maintenance are particularly convenient. To this end, it relates to a device for distributing a cryogenic liquid of the aforementioned type, characterized in that the three conduits pass through a sealed joint a plate fixed in the neck, at the inlet of the internal tank, and in that that the two openings are the single openings of the inner tank and the outer shell.

• - la conduite de déversement est pourvue d'une électrovanne d'arrêt disposée au-dessus de la plaque, et, éventuellement, cette dernière est également traversée à joint étanche par des moyens de commande de l'électrovanne;
• - la conduite d'évacuation est pourvue, au niveau de la plaque et au-dessous de l'électrovanne, d'un insert percé d'un orifice calibré de diamètre très inférieur à celui de cette conduite.

According to advantageous characteristics:

• - The discharge pipe is provided with a stop solenoid valve disposed above the plate, and, optionally, the latter is also crossed with a seal by means of control of the solenoid valve;
• - The evacuation pipe is provided, at the level of the plate and below the solenoid valve, with an insert pierced with a calibrated orifice of diameter much smaller than that of this pipe.

• la figure 1 est une vue en coupe longitudinale d'un dispositif de distribution conforme à l'invention;
• la figure 2 est une vue de détail, à plus grande échelle, de la partie inférieure de ce dispositif, et
• la figure 3 est une vue en coupe transversale prise suivant la ligne III-III de la figure 2.

An exemplary embodiment of the invention will now be described with reference to the accompanying drawings, in which:

• Figure 1 is a longitudinal sectional view of a dispensing device according to the invention;
• FIG. 2 is a detail view, on a larger scale, of the lower part of this device, and
• FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2.

The dispensing device shown in the drawings in its position of use is intended to supply a continuous stream of liquid nitrogen to a succession of cylindrical metal cans (not shown) which scroll just below at high speed, contain a foodstuff such than a non-carbonated drink and are driven in horizontal translation by a conveyor (not shown).

This device essentially comprises a cryogenic container of conventional construction consisting of an internal tank 1 having a capacity of the order of one liter to several tens of liters, an external envelope 2 and a connecting neck 3, and arranged in an inverted position.

The internal reservoir 1 and the external envelope 2, which are for example made of aluminum, each have a cylindrical running part and two domed bottoms, the internal bottom being pierced with a large circular opening 4.

The neck 3 is a section of tube fixed with a seal at its ends around the periphery of the two openings 4, by means of respective solid rings 5, 6. These two rings are themselves welded around the openings 4 and the neck 3 may be made of stainless steel and be welded to the rings 5, 6. The ring 5 defines inside the neck 3 a horizontal annular shoulder 7 provided with several holes and facing downwards.

Between the reservoir 1 and the envelope 2 is delimited an annular space 8 with vacuum-insulated insulation, the pumping being carried out by a connector 9. As a variant, the insulation could be produced from an injected insulating material such as polyurethane, or by any other suitable means.

• - un tube-évent 11, qui s'étend verticalement de la partie supérieure du réservoir 1 à un emplacement situé au-dessous de la bague 6;
• - un tube 12 d'alimentation en azote liquide, qui pénètre à joint étanche dans le tube 11 sous la bague 6 puis monte dans le tube pour en émerger, au sommet du réservoir 1, sous la forme d'une crosse de déversement 13;
• - une conduite verticale 14 d'évacuation d'azote liquide munie à son extrémité supérieure (figure 2) d'un manchon 15, par exemple en matière plastique, qui est maintenu dans un perçage de la plaque 10 par un écrou 16. Dans le manchon 15 est positionné un insert 17 percé d'un orifice calibré dont le diamètre est très inférieur au diamètre de ce manchon et de la conduite 14. Le manchon 15 débouche au-dessus de la plaque 10, dans le réservoir 1, et est coiffé par une électrovanne 18 fixée sur la face supérieure de cette plaque. Cette électrovanne est une électrovanne cryogénique immergée d'un type disponible dans le commerce;
• - un raccord 19 servant au passage de fils électriques 20 de commande de l'électrovanne 18; et
• - un dispositif de mesure de niveau qui, dans cet exemple, est constitué par un tube 21 destiné à être raccordé à un manomètre et se terminant, légèrement au-dessus de la plaque 1 0, par une cloche 22 ouverte vers le bas. Dans un but de clarification du dessin, seule la partie supérieure de ce dispositif a été représentée à la figure 2.

On the shoulder 7 is applied and is centered a massive plate 10, which is fixed by a few screws in a removable manner on the inner ring 5. This plate 10 is crossed with a seal by the various members allowing the operation of the device:

• - a vent tube 11, which extends vertically from the upper part of the reservoir 1 to a location located below the ring 6;
• - A tube 12 for supplying liquid nitrogen, which penetrates into the tube 11 under seal 6 under the ring 6 and then rises in the tube to emerge therefrom, at the top of the tank 1, in the form of a discharge butt 13;
• a vertical pipe 14 for discharging liquid nitrogen provided at its upper end (FIG. 2) with a sleeve 15, for example made of plastic, which is held in a hole in the plate 10 by a nut 16. In the sleeve 15 is positioned an insert 17 pierced with a calibrated orifice whose diameter is much less than the diameter of this sleeve and of the pipe 14. The sleeve 15 opens above the plate 10, in the reservoir 1, and is capped by a solenoid valve 18 fixed on the upper face of this plate. This solenoid valve is a cryogenic submerged solenoid valve of a type available on the market;
• - A connector 19 for the passage of electric wires 20 for controlling the solenoid valve 18; and
• - A level measuring device which, in this example, consists of a tube 21 intended to be connected to a pressure gauge and ending, slightly above the plate 1 0, by a bell 22 open downwards. In order to clarify the drawing, only the upper part of this device has been shown in FIG. 2.

The tubes 11 and 21 are welded to the plate 10, while the removable members 15 and 19 are fixed thereto by means of seals. Likewise, a seal is provided between the ring 5 and the plate 10.

The device also comprises a rigid ring 23 welded to the upper end of the casing 2 and provided with hooks 24 (one of which has been shown in FIG. 1), and a lower cover 25. The latter consists of on the one hand a ferrule 26 welded to the lower end of the casing 2 and provided with at least one handling handle 27, and on the other hand a lower cover 28 detachably fixed on the ferrule 26 and crossed by the vent 11 and by the pipe 14.

In addition, a connection box 29 (not shown in FIG. 2) is fixed to the ferrule 26. This box comprises a solenoid valve assembly 30 - connection 31 mounted at the end of the pipe 12, a connection 32 to which the tube ends. 21, and an electrical connector 33 to which the electrical wires for controlling the solenoid valves 18 and 30 end.

The space remaining free in the neck and between the envelope 2 and the cover 25 is filled with an appropriate thermally insulating material 34.

In service, the device is suspended by the hooks 24 on an appropriate support (not shown), the axis of the pipe 14 meeting at a right angle to that of the conveyor which carries the boxes to be pressurized.

There is connected to the box 29 a line for drawing off a storage of liquid nitrogen under a pressure greater than atmospheric pressure (connection 31), a pressure gauge (connection 32) and an electrical supply cable (connection 33).

The solenoid valve 18 being closed, the solenoid valve 30 is opened, which causes the filling of the reservoir 1 to a high level detected by the pressure gauge. To discharge the liquid nitrogen, the solenoid valve 18 is opened, which is fully submerged and therefore does not provide heat. Frank liquid fills the sleeve 15, passes through the calibrated orifice of the insert 17 and flows freely in a thread along the axis of the pipe 14, without touching the latter. The nitrogen vaporized in the tank 1 is evacuated at atmospheric pressure through the vent 11.

The jet of liquid nitrogen can be stopped at any time by simply closing the solenoid valve 18. The filling of the reservoir 1 is carried out automatically by controlling the solenoid valve 30 in all or nothing from signals supplied by the manometer in order to maintain an approximately constant height of liquid in the tank and, consequently, obtain uniform conditions for the distribution of liquid nitrogen in the boxes to be pressurized.

• - à la construction, le fait de n'avoir qu'une ouverture par laquelle passent tous les organes nécessaires au fonctionnement facilite grandement la réalisation du récipient cryogénique. Il n'y a pas de bridage mécanique, et l'on évite ainsi les contraintes internes. Cet avantage est valable si l'isolation de l'interparoi 8 est constituée d'une matière isolante injectée et a fortiori dans le cas d'une isolation sous vide, dont l'épaisseur est plus faible;
• - à l'utilisation, le fait que toutes les fonctions sont regroupées au bas du dispositif permet d'utiliser un système de connexion centralisé (boîte de connexion 29). Cette commodité est appréciable à la fois au moment du montage et au moment d'une éventuelle intervention de maintenance;
• - pour démonter le dispositif, il suffit de déconnecter les liaisons de la boîte 29; de soulever le récipient pour le décrocher; de le retourner, même s'il est plein d'azote liquide; d'ôter le couvercle 28 et l'isolation 34; et de dévisser puis d'extraire la plaque 10, et avec elle l'ensemble des organes qu'elle porte. Cela permet en particulier de changer l'insert 17 pour modifier le débit d'azote liquide;
• - l'alimentation en azote liquide et l'évacuation d'azote gazeux à travers le col 3, à proximité immédiate de la conduite 14, contribuent au maintien en froid de la région inférieure du dispositif.

The device described above has many advantages:

• - During construction, having only one opening through which all the organs necessary for operation pass greatly facilitates the production of the cryogenic container. There is no mechanical clamping, and internal stresses are thus avoided. This advantage is valid if the insulation of the interwall 8 consists of an injected insulating material and a fortiori in the case of vacuum insulation, the thickness of which is thinner;
• - in use, the fact that all the functions are grouped together at the bottom of the device makes it possible to use a centralized connection system (connection box 29). This convenience is appreciable both at the time of assembly and at the time of a possible maintenance intervention;
• - To dismantle the device, simply disconnect the connections from the box 29; lift the container to unhook it; return it, even if it is full of liquid nitrogen; to remove the cover 28 and the insulation 34; and unscrew then extract the plate 10, and with it all of the members that it carries. This allows in particular to change the insert 17 to modify the flow of liquid nitrogen;
• the supply of liquid nitrogen and the evacuation of gaseous nitrogen through the neck 3, in the immediate vicinity of the pipe 14, contribute to keeping the lower region of the device cold.

As a variant, as shown in FIG. 2, the external part of the vent 11 can be shaped into a tunnel 11 A overhanging the conveyor in order to create a more or less inert protective atmosphere in the gas volume existing in the boxes to be pressurized. Furthermore, the connector 19 can be omitted, the electrical wires 20 passing along the vent 11.

Alternatively also, the vent 11 can be bent at its upper end and be provided with a cage containing a float. Thus, the vent 11 closes automatically when the liquid reaches the high level, and the pressure balances with that of the filling line (for example two absolute bars).

In this case, one can do without the pressure device 21-22 and the solenoid valve 30, because the liquid is kept high at the automatic level, and the injection of liquid nitrogen through the pipe 14 can perform under a certain pressure, which allows for example to perform a spraying of liquid nitrogen on a determined surface.

It is understood that the device according to the invention applies to various cases where it is necessary to obtain a reliable and controlled injection of a cryoene franc liquid, in particular at low flow rate. If desired, the pipe 14 can be connected to a horizontal manifold itself provided with several discharge orifices arranged at several points in a packaging chain, for example to provide inerting or localized cooling.

Claims (13)

1. A device for distributing a cryogenic liquid, of the type comprising:

- a cryogenic vessel (1, 2) having double walls and which is inverted in its position of utilisation and which on the one hand comprises an inner reservoir (1) and an outer jacket (2), each having an opening (4) at its lower extremity, and on the other hand a neck (3) interconnecting the two openings (4), and

- a duct (12) for supply of cryogenic liquid, a venting pip (11) and a discharge pipe (14), characterised in that the three pipes (11, 12, 14) are passed with a fluid tight seal through a plate (10) secured in the neck, and at the inlet of the inner reservoir (1), and in that the two openings (4) are the sole openings of the inner reservoir (1) and of the outer jacket (2).

2. A device according to Claim 1, characterised in that the said plate (10) is fastened in a removable manner on a coupling ring (5) connecting the neck (3) to the inner reservoir (1).

3. A device according one of the Claims 1 and 2, characterised in that the discharge pipe (14) is provided with an electromagnetic stop valve (18) placed above the plate (10).

4. A device according Claim 3, characterised in that the plate (10) is also traversed with a fluid tight joint by means (19, 20) for controlling the electromagnetic valve (18).

5. A device according to Claim 4, characterised in that the discharge pipe (14) is provided at the level of the plate (10) and below the electromagnetic valve, with an insert (17) pierced by a calibrated orifice having a much smaller diameter than that of this pipe.

6. A device according to any one of Claims 1 to 5, characterised in that the plate (10) is also traversed with a fluid-tight joint by a level measuring device (21, 22).

7. A device according to Claim 6, characterised in that the level measuring device comprises a pipe (21) which terminates within the inner tank (1) in a downwardly open bell (22) and those outer extremity is intended to be connected to a pressure gauge.

8. A device according to any one of the Claims 1 to 7, characterised in that the intermediate space of the neck (3) is filled with a heat insulating material (34).

9. A device according to any one of the Claims 1 to 8, characterised in that a ring (23) provided with hanging means (24) is secured on the upper end of the outer jacket (2).

10. A device according to any one of the Claims 1 to 9, characterised in that a hoop (26) provided with a manipulation handle (27) is secured on the lower extremity of the outer jacket (2).

11. A device according to anyone of the Claims 1 to 10, characterised in that the assembly of elements (12, 20,21) acting to supply cryogenic liquid and if applicable to provide an electrical supply and/or a level measurement, are coupled to a connection box (29) carried by the vessel.

12. A device according to any one of the Claims 1 to 11, characterised in that the outer extremity of the vent pipe (11) is produced in tunnel form (11 A) intended to engender a particular atmosphere over objects which run past beneath the distribution device.

13. A device according to any one of Claims 1 to 12, characterised in that the inner extremity of the vent pipe (11) is povided with a float cage, the feed pipe (12) being connected direct to a store of cryogenic liquid under pressure whilst in use.

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