WO1999002048A1

WO1999002048A1 - System for storing items or products in a conditioned atmosphere

Info

Publication number: WO1999002048A1
Application number: PCT/NL1998/000393
Authority: WO
Inventors: Hugo Sebastiaan Maria De Vries
Original assignee: Instituut Voor Agrotechnologisch Onderzoek (Ato-Dlo)
Priority date: 1997-07-08
Filing date: 1998-07-08
Publication date: 1999-01-21
Also published as: NL1006509A1; AU8246598A; NL1006509C2

Abstract

System for storing items or products which have to be preserved in a conditioned atmosphere, comprising a number of components, namely a number of essentially closed containers (10a, 10b, 10c) provided with an inlet connection (12a, 12b, 12c) and an outlet connection (14a, 14b, 14c), atmosphere-conditioning equipment, likewise provided with an inlet connection and an outlet connection, which equipment is accomodated in one or more containers of the same type as the containers mentioned above. All the components, starting with the atmosphere-conditioning equipment, are connected in series by virtue of the fact that an outlet connection of one component is connected to the inlet connection of the next component in the series, etc. Preferably, the containers are provided with a filter which is permeable to certain atmospheric constituents, so that after removal of the series circuit a modified atmosphere is maintained.

Description

System for storing items or products in a conditioned atmosphere

The invention relates to a system for storing items or products which have to be preserved in a conditioned atmosphere, comprising a number of components, namely

- a number of essentially closed containers provided with an inlet connection and an outlet connection,

- atmosphere-conditioning equipment, likewise provided with an inlet connection and an outlet connection, all the components, starting with the atmosphere-conditioning equipment, being connected in series by virtue of the fact that an outlet connection of one component is connected to the inlet connection of the next component in the series, etc.

A system of this kind is known from Japanese Patent Application JP60-30638.

In this known system, the holders are situated inside a chamber in which the temperature is maintained at a predetermined value with the aid of cooling equipment, which is installed partly inside and partly outside the chamber. The further atmosphere-conditioning equipment is installed outside the chamber. All the containers are connected in series by virtue of the fact that the outlet connection of the first container is connected to the inlet connection of the second container, etc. The connections between the outlet connection of one container and the inlet connection of the following container are in each case realized with the aid of separate lines.

Furthermore, the atmosphere-conditioning equipment is connected in a closed circuit with the series of containers. The connection between the outlet connection of the last container in the series and the atmosphere-conditioning equipment, and the connection between the atmosphere-conditioning equipment and the inlet connection of the first container in the series, are also realized using separate lines.

This known system is obviously intended for stationary use, for example in storage areas, warehouses, ships' holds and the like. During operation, first of all the containers are filled with the items or products to be preserved, and then they are closed and placed in the cooling chamber. Then, the necessary connections are made using connecting hoses, in such a manner that the containers and the atmosphere- conditioning equipment outside the cooling chamber are placed in a closed circuit through which conditioned air can successively be blown through all the containers, in order to ensure that the atmosphere in all these containers satisfies predetermined parameters.

A drawback of this known system is the fact that a large number of hoses and/or tubes are required in order to make the necessary connections so as to realize the closed air-circulation circuit. In addition to the large amount of extra material, this also requires skilled personnel to make these connections with the necessary care so as to obtain the desired result. Furthermore, owing to all these hose or tube connections, it is not easy to remove one or a number of selected containers from the system. The presence of all the hoses or tubes moreover leads to an increase in the space required. The object of the invention is to provide a system which is easy to transport as a single unit, preferably requires few operations to accommodate all the components of the equipment in a circuit and is preferably flexible with regard to the position of the various components in the system.

This object is achieved by means of a system of the type described in the first paragraph which, according to the invention, is characterized in that the atmosphere- conditioning equipment is accommodated in one or more containers of the same type as the containers mentioned above, and that the inlet connections and outlet connections are embodied such that they can be interconnected without further additional components. By accommodating the atmosphere-conditioning equipment in one or more containers of the same type as the containers in which the items or products to be preserved are stored, all the components of the system are given the same appearance. This considerably assists with handling the entire system.

In order to limit the space which is required for the atmosphere-conditioning equipment and to facilitate assembly of a system, it is preferable for the atmosphere- conditioning equipment to be accommodated in a single container of the same type as the containers mentioned above.

This means that only one equipment container has to be present in each system, while all the other containers can be used to store items or products. In order to be able to draw a clear distinction between the container(s) in which the conditioning equipment is accommodated and the other containers, it is preferable for the container(s) in which the conditioning equipment is accommodated to be recognizable by sight. In order to prevent the need, when used for other items or products, for adjustment means inside the container containing the conditioning equipment having to be operated, it is preferable for the container(s) in which the atmosphere-conditioning equipment is accommodated to be provided with externally accessible operating elements, with which the desired conditions of the atmosphere, brought about by the atmosphere-conditioning equipment, can be influenced.

The ease of handling of the system is promoted further if the containers are designed as identical stackable holders with the inlet and outlet connections in each case at corresponding positions. By simply stacking a number of containers and, in the process, ensuring that one of the containers contains the conditioning equipment, a system which functions completely independently can be realized in a simple manner.

This independent character is even more apparent if the container with the atmosphere-conditioning equipment is also provided with an independent power source from which the atmosphere-conditioning equipment is supplied (or can be supplied). Within the context of the invention, the containers may have all kinds of different shapes, for example may be barrel-like or cylindrical containers. In order to utilize the storage space available inside a warehouse or the like as efficiently as possible, however, it is preferable for each holder to be formed as a rectangular holder with mutually parallel top and bottom walls and four side walls. Depending on the nature of the items or products in the various containers, specific demands are placed on the atmosphere inside the container. In many cases, the conditioning equipment can easily satisfy these demands if there is a closed air- circulation circuit, as is known, for example, from the abovementioned Japanese Patent Application JP60-30638. The system according to the invention may in this context be designed in such a manner that the outlet connection of the last container in the series is connected via a pipe or hose to the inlet connection of the atmosphere-conditioning equipment, so that the series circuit is converted into a closed loop. This brings about a considerable reduction in the number of hoses or tubes required by comparison with the system disclosed by the said Japanese Patent Application JP60-30638a. In order to facilitate making the connections between the inlet and outlet connections, it is preferable for the connections to be of a type which is closed in the uncoupled state and is opened when brought into the coupled state.

In fact, in this case, use can be made of couplings which are known per se and are designed in such a way that when a line is slotted into place the valve in the inlet or outlet connection is opened automatically.

A controlled atmosphere (CA for short) prevails inside a system according to the invention as described thus far. In this CA environment percentages of certain gases, such as oxygen, carbon dioxide, nitrogen, atmospheric humidity and other volatile substances are monitored and regulated. A good circulation, either in a closed circuit or in an open flow path, is important in this connection in order to prevent a build up of undesirable gases at a location in the system.

In order to maintain the conditioned atmosphere in a container for as long as possible, even after the container has been removed from the system, it is preferable for at least a number of containers within the system to be provided with a filter which is arranged in one of the walls and is permeable to a predetermined extent to certain constituents from the atmosphere in the container. Filters of this kind are known per se, for example from US 4,842,875. However, the storage container described in that patent is not suitable for use within a system described in this application.

A modified atmosphere (MA for short) prevails inside a container which is provided with a filter of this kind. Owing to the fact that certain gases and/or volatile substances can pass out through the filter and other gases and volatile substances cannot pass out of the container, or do so at a much slower rate, a predetermined MA environment is maintained inside the container.

In order, in the position in which the container is situated in the system described above, to prevent any parasitic influence exerted by the filter on the air circuit, it is preferable for it to be possible to close off the filter by means of a cover, film or something similar. Closing off filters which are present can be realized in particular by the fact that the filters are closed off by the holder situated at a higher level when the holders are stacked.

The invention will be discussed in more detail below with reference to the appended figures, in which: Figure 1 diagrammatically shows a first embodiment of a system according to the invention,

Figure 2 shows a diametral section through the containers from Figure 1 in the stacked state. Figure 3 shows how a closed air-circulation circuit can be realized using a single tube or hose.

Figure 4 diagrammatically shows a second embodiment of a system according to the invention. Figure 5 shows the way in which a closed loop can be realized without the need for a separate external tube or hose.

Figure 6 shows an embodiment of a container provided with a filter membrane in one of the walls.

Figure 7 shows another embodiment of a container provided with a filter membrane in one of the walls.

Figure 1 illustrates a first embodiment of a system according to the invention.

In this system, containers 10a, 10b, 10c ... are used, each provided with an inlet connection 12a, 12b, 12c ... and an outlet connection 14a, 14b, 14c ... Apart from the inlet and outlet connections, the containers lOx are completely closed. (It will be clear that the container will be provided with a facility for loading or unloading items or products into or from the container, for example in the form of a door, a lid or a removable wall, but in the context of the invention this does not play any further role).

The various containers 10a, 10b, 10c ... can be stacked on top of one another, in such a manner that in each case an outlet connection of a container positioned at a lower level can be coupled to the inlet connection of a container positioned above it.

In order to make this possible, each container must in each case be rotated through

180° about its central vertical axis, in the manner illustrated in Figure 1. As a result, it is possible for the outlet connection 14a of the container 10a to be coupled to the inlet connection 12b of container 10b. If the container 10c is then placed on top of the container 10b, the outlet connection 14b of container 10b can be coupled to the inlet connection 12c of container 10c.

The coupled inlet/outlet connections form an open air flow path. If it is assumed that the connections 12a and 14c are open, it will be clear that an open air passage through the containers stacked on top of one another is realized, starting from the inlet connection 12a and ultimately ending at the outlet connection 14c.

Now, within the context of the invention, equipment for conditioning the atmosphere is placed in one of the containers. Figure 2 shows a section along a diagonal plane through the stacked containers 10a, 10b and 10c. This figure therefore also shows the coupled inlet/outlet connections 14a/ 12b and 14b/ 12c. Furthermore, the figure diagrammatically indicates the equipment 16 which is installed in the bottom container 10a. This equipment 16 may, for example, be a fan, by means of which a flow of air can be maintained, a cooling element, by means of which the air can be cooled, a drying element with which any moisture can be removed from the air, filter elements, with which dust particles and/or microorganisms can be removed, filters, with which certain gases can be completely or partially filtered out, or metering units, with which certain gases which are not normally present can be added to the atmosphere, and the like. Configuring and installing equipment 16 in order to realize a CA environment (conditioned atmosphere) inside the containers for certain items or products is assumed to be known per se and is therefore not discussed in more detail.

In the situation illustrated in Figure 2, the fan, which is assumed to form part of the equipment 16, draws air in via the inlet opening 12a. This air is conditioned by the equipment 16 in the desired manner and then begins to flow through the air flow path which is formed by the coupled connections 14a/12b, 14b/12c, and then leaves the stack of containers via the outlet connection 14c. As indicated by arrows in Figure

2, the conditioned air will flow right through each of the containers, from the inlet connection in one corner in the region of the bottom to the outlet connection in the diametrically opposite corner in the region of the top wall of each container. All kinds of different items or products can be preserved under a conditioned atmosphere in the containers 10a, 10b, 10c. Consideration may be given, for example, to fruit or vegetables, meat, eggs and other plant or animal products. Consideration may also be given to old books, cards or other paper products, chemicals etc.

Depending on the items or products, the equipment 16 has to function in a suitably adapted manner. In order to allow certain parts of the equipment 16 to be adjusted and started up without having to open the container 10 A, a control panel 17, which is diagrammatically illustrated in Figure 1, is installed in one of the side walls. This panel 17 contains sufficient operating members to be able to set the required parameters, which determine the characteristics of the atmosphere inside the containers, from the outside.

In some cases, it may be preferable to make the open air path illustrated in Figures 1 and 2 into a closed, continuous air path. In a closed circuit, it could be possible to employ a smaller cooling installation in the equipment 16, filters with a smaller capacity could, for example, be used, or a specific, desired content of gas, for example a specific, desired percentage of oxygen or nitrogen, can be maintained inside the container chambers much more easily.

To create a closed air flow path of this nature, it is possible, for example, to couple the outlet connection 14c to the inlet connection 12a via a pipe or hose 18. If the bottom container 10a is standing on the ground, connecting the hose 18 to the inlet connection 12a can lead to problems, in which case the bottom container may, for example, be provided with an additional inlet connection 22a which is in fact in parallel with the inlet connection 12a. This extra inlet connection 22a in one of the side walls can then be used to connect the tube or hose 18 which closes the air- circulation path to form a loop.

In the situation shown in Figure 2, where there is an open air flow circuit, the equipment 16 must generally be installed at the start of the air path, i.e. in the example illustrated in the bottom container 10A. In the situation shown in Figure 3, which deals with a closed air flow circuit, in principle there are no specific requirements relating to the position of the container in which the equipment 16 is situated. Nevertheless, even in that case the equipment 16 is preferably installed in the bottom container, since the containers positioned at higher levels can then be removed more easily if necessary without the equipment container 10A having to be moved unnecessarily. It is furthermore preferable for the equipment container to be clearly recognizable by sight, for example to be of a colour which differs (considerably) from the colour of the other containers. This facilitates stacking the various containers into a system, and it is only necessary to check the colour in order to see whether there is an equipment container present in a system. If necessary, for example in the case of systems in which the containers are stacked into a relatively high stack, it is possible for a plurality of equipment containers to be present in a system. An additional equipment container halfway through the circuit considerably reduces any gradient in the atmosphere parameters which are to be regulated. In the figures, the containers are shown as rectangular holders. Within the context of the invention, the containers may be of all kinds of shapes. The only demand placed on the containers is that the containers must be stackable, in such a manner that the inlet openings and outlet openings which are to be coupled together can be coupled easily during stacking. It is thus possible to employ cylindrical containers of round or polygonal cross-section, barrel-like containers and the like. However, rectangular containers are preferred in connection with efficient use of space. The couplings are preferably of a type which, in the uncoupled state, forms a closure and, in the coupled state, creates an open passage. More particularly, the couplings are designed in such a way that, during coupling, the couplings automatically switch from the closed to the open state and, during uncoupling, the couplings automatically change from the open state to the closed state. Such couplings are known per se and are therefore not discussed in more detail. In the event that a closed air circuit is used, as shown in Figure 3, the hose 18 is also provided with couplings of the type described. If an open air circuit as shown in Figure 2 is preferred, measures must be taken in order to open the inlet connection 12A and also the outlet connection 14C. In both cases, this can be achieved easily by attaching a separate mating coupling. Depending on the type of coupling and the way in which they are fitted in the wall of the container, it may be necessary, if appropriate, to provide the containers with legs, supporting rims, spacers and the like, in order to ensure correct mutual positioning and thus correct functioning of the couplings. If appropriate, further elements which fit inside one another, such as dowel pins or other elements, may be provided in order to facilitate correct positioning of the containers.

Another embodiment of the containers is shown in Figure 4. In the system shown in that figure, the box-shaped containers 30a, 30b and 30c used are each provided with an inlet connection 32a, 32b, 32c ... which is situated in the centre of the base and an outlet connection 34a, 34b, 34c ... which is situated in the centre of the top wall. In this embodiment, there is little need to pay attention to the position of the various containers. They are easy to stack on top of one another, in each case the outlet connection of the box situated at a lower level, for example 34a, coupling easily to the inlet connection of the box situated at a higher level, for example 32b. In order to prevent the air inside each- container from flowing directly from inlet opening to outlet opening, a baffle plate 38b, 38c is arranged in each container, by means of which plate the air from the inlet is firstly guided towards the side walls of the container. The baffle plate 38b, 38c does not extend right to the side walls, and therefore the air can rise around this plate and then flow through the entire container chamber before reaching the outlet opening 34b, 34c. The container 30a in which the conditioning equipment 36 is arranged does not need such a baffle plate 38. The inlet opening 32a can be coupled directly to the equipment 36.

Instead of a completely closed baffle plate, it is also possible to employ a perforated baffle plate, in which case the percentage of the plate which allows air through preferably increases from the inside outwards. It is also possible to design the baffle plate as a filter plate, by means of which, by way of example, dust particles emanating from containers connected upstream can be removed from the air stream. In that case, it may be preferable for the baffle plate to run all the way from wall to wall. Figure 5 shows an embodiment of the system in which the box-shaped containers 40a, 40b and 40c are used. In the same way as illustrated in Figure 4, each container (with the exception of the bottom equipment container 40A) is provided with an inlet connection 42b, 42c ... which is situated in the centre of the base and an outlet connection 44a, 44b, 44c ... which is situated in the centre of the top wall. Furthermore, in this embodiment each container is provided with a pipe section 46a, 46b, 46c ..., which is preferably arranged in a corner of the container. Each pipe section runs from the base to the top wall and is not in contact with the interior of the container. Only in the container 40A in which the conditioning equipment 48 is accommodated does the pipe section 46a run from the top wall to the entrance to the equipment 48. If the containers are stacked on top of one another, all the pipe sections adjoin one another and can be used as a return line, in which case it is only necessary, at the top container, to use a hose 49 to make a connection between the outlet connection 44C and the top end of the pipe section 46C, in the manner shown in the figure. In order to maintain the conditioned atmosphere in a container for as long as possible even after the container has been removed from the system, it is preferable to provide the containers with a filter which is arranged in one of the walls and is permeable to a predetermined extent to certain constituents of the atmosphere in the container. As has already been pointed out above, filters of this kind are known per se. In Figure 6, as an example, a filter membrane 56 is arranged in the top wall of a container 50 which is provided with an inlet opening 52 in the region of a corner of the base and an outlet opening 54 situated diametrically opposite in the top wall. This container 50 is thus of the same type as that shown in Figure 1. If the container is removed from a system, the couplings in the inlet 52 and outlet 54 will close and the atmosphere will still be maintained in the modified state for a long period of time owing to the presence of the membrane 56, because certain constituents of the internal atmosphere are allowed to pass out through the membrane and other constituents are not allowed through, or are allowed through to a lesser extent.

Figure 7 shows a container 60 of the same type as that shown in Figure 4. Since this container 60 is provided with a centrally located outlet connection 64 (and a centrally located inlet connection 62), in this embodiment two small membranes 66A and 66B, as shown in the figure, are selected. Owing to the considerable flexibility in the design of the system according to the invention, this system can be used for a large number of different applications.

An important application area of the system is the preservation or at least temporary storage of agricultural products, such as vegetables, fruit, flowers, seeds, etc. During harvesting, one or more containers can be filled on site (for example in the field, in the orchard, etc.) and transported to a storage location, where they are coupled together with other containers to form a system (or to form a plurality of systems). By conditioning the atmosphere in each of the systems in a predetermined manner, it is possible, for example, to lengthen the shelf-life of vegetables and fruit considerably, and it is possible to create conditions for gradual ripening of, for example, certain varieties of fruit, or it is possible to ensure that, for example during storage of seeds, no fungus is formed. If desired, one or more containers can be uncoupled from the system (or from the systems) and then transported to another location. If the containers in question are provided with suitable filters in the walls, these containers serve as so- called MA containers (containers with a modified atmosphere) during transportation. Once they have arrived at their destination, they may still serve as MA containers for a considerable time, and may also once again be incorporated, if appropriate with other containers, in a system, with the result that the atmosphere is reconditioned and the desired CA conditions are again maintained.

With a number of systems according to the invention, it is possible, for example, to preserve products at different stages of ripening and of different cultivated varieties, each under specific conditioned atmospheres.

Certainly, if the quantities of products to be preserved are not too great and the size of a complete system can be kept relatively small, it is possible to use relatively small containers (even for accommodating the conditioning equipment), so that such systems are suitable in particular for organically grown products.

Since the contents of a container remain protected under CA conditions if the container is accommodated in a system and are maintained under MA conditions if the container is transported as an independent unit, it is possible to use one and the same storage system from the point at which the container is filled with items or products until it reaches the consumer. This avoids the adverse effects of, for example, transfer to other storage facilities and the like.

Due to the fact that there are no specific demands placed on the actual dimensions of the containers within the context of the invention, it is possible to employ both large containers, for example for relatively large and heavy products, and also relatively small containers, for example for soft fruit, which preferably should not be stacked, and, for example, for preprepared meals.

In addition to agricultural products, such as fruit and vegetables, systems according to the invention can also be successfully used for storing and distributing, for example, pictures, books, films, slides, photographic material and other archive material which has to be stored under an optimum atmosphere (temperature, atmospheric humidity, CO₂ content and the like).

Claims

1. System for storing items or products which have to be preserved in a conditioned atmosphere, comprising a number of components, namely - a number of essentially closed containers provided with an inlet connection and an outlet connection,

- atmosphere-conditioning equipment, likewise provided with an inlet connection and an outlet connection, all the components, starting with the atmosphere-conditioning equipment, being connected in series by virtue of the fact that an outlet connection of one component is connected to the inlet connection of the next component in the series, etc., characterized in that the atmosphere-conditioning equipment is accommodated in one or more containers of the same type as the containers mentioned above, and that the inlet connections and outlet connections are embodied such that they can be interconnected without further additional components.

2. System according to Claim 1, characterized in that the atmosphere-conditioning equipment is accommodated in a single container of the same type as the containers mentioned above.

3. System according to one of the preceding claims, characterized in that the container(s) in which the atmosphere-conditioning equipment is accommodated can be recognized by sight.

4. System according to one of the preceding claims, characterized in that the container(s) in which the atmosphere-conditioning equipment is accommodated are provided with externally accessible operating elements, with which the conditioning of the atmosphere, brought about by the atmosphere-conditioning equipment, can be influenced.

5. System according to one of the preceding claims, characterized in that the containers are designed as identical stackable holders with the inlet and outlet connections in each case at corresponding positions.

6. System according to Claim 5, characterized in that the outlet connection of the top container in the stack is connected, via a pipe or hose, to the inlet connection of the bottom container.

7. System according to Claim 5 or 6, characterized in that the atmosphere- conditioning equipment is accommodated in the bottom container of a stack.

8. System according to one of the preceding claims, characterized in that each holder is formed as a rectangular holder with mutually parallel bottom and top walls and four side walls.

9. System according to Claim 8, characterized in that one of the connections (inlet or outlet) is arranged in the top surface and the other connection (outlet or inlet, respectively) is arranged in the bottom surface, in such a manner that when stacking the holders in each case the connection in the top surface of the holder positioned at the lower level can be aligned with the connection in the bottom surface of the holder positioned at a higher level.

10. System according to Claim 9, characterized in that the inlet connection is arranged in the region of one of the comers in the bottom surface and in that the outlet connection is arranged diametrically opposite in the top surface.

11. System according to Claim 9, characterized in that the inlet connection is arranged in the centre of the bottom surface, and in that the outlet connection is arranged centrally in the top surface.

12. System according to one of Claims 5-11, characterized in that the connections are furthermore designed in such a way that they are coupled automatically during stacking.

13. System according to one of the preceding claims, characterized in that the connections are of a type which is closed in the uncoupled state and is opened when brought into the coupled state.

14. System according to one of the preceding Claims 5-13, characterized in that each container is provided with a conduit section which runs through the container from the top downwards, in such a manner that, in the stacked state, these conduit sections adjoin one another and form a conduit.

15. System according to one of the preceding claims, characterized in that at least a number of containers are provided with a filter which is arranged in one of the walls and is permeable to a predetermined extent to certain constituents from the atmosphere in the container.

16. System according to Claim 15, characterized in that the filter can be closed off by means of a cover, film or something similar.

17. System according to Claim 15 or 16, referring back to one of Claims 5-13, characterized in that the filters are closed off by the holder situated at a higher level when the holders are stacked.