WO2005039654A1

WO2005039654A1 - Device and method for eliminating vermin in containers

Info

Publication number: WO2005039654A1
Application number: PCT/NL2003/000716
Authority: WO
Inventors: Frederik Bergwerff
Original assignee: Ecogen Holding B.V.
Priority date: 2003-10-23
Filing date: 2003-10-23
Publication date: 2005-05-06
Also published as: AU2003275731A1

Abstract

The invention relates to a method and a device for eliminating vermin in great cargos, especially cargos transported in containers (17), in which said containers (17) are brought into a sealable space (3, 4, 13, 14), a low-oxygen mixture (35) is fed into the sealed space (3, 4, 13, 14), in which the temperature of the gas mixture within the sealed space is brought within a predetermined range, such that the products to be treated achieve a predetermined temperature and in which the air humidity of the heated gas mixture is controlled in order to prevent dehydration of said products.

Description

Device and method for eliminating vermin in containers

The present invention relates to a method and device for eliminating vermin in containers and especially vermin in the cargo located therein. Here, vermin is substantially understood to mean insects, including the larvae and eggs, which may occur in or on the cargo, but also in or on the wooden packaging materials and transport materials. The wooden packaging materials and transport materials comprise, among other things, pallets, crates, cases, industrial packages, cable drums, stow wood and the like which are used for supporting, protecting or carrying the cargo. Among the usual methods for eliminating such vermin is the use of pesticides, including the highly toxic methyl bromide. According to the Montreal Protocol, the use of methyl bromide will be phased-out in time, in order to eliminate its contribution to the disintegration of the ozone layer. However, phasing out for the so-called QPS (Quarantine Pre Shipment) applications may not take place for years. Due to the economical interests of especially the suppliers of chemical pesticides and their extremely effective lobby, phasing out the use of methyl bromide for QPS application is quite troublesome. Most probably, phasing-out for QPS applications will not start before some (4-6) years. The use of methyl bromide for QPS applications may in the short run even increase explosively as a consequence of adoption of the IPPC (FAO) regulation by a number of big trading nations (US, Canada, Mexico and China) . Therefore, the object of the invention is to provide a method by which said vermin can be reliably eliminated, by which elimination of vermin in big cargos is possible in one run and in which the cost for elimination are at least competitive with those of the known methods and in which the QPS requirements in relation to wooden packaging materials in containers as stated in the international standard for phytosanitary measures wooden packagings PAO-ISPM no. 15, March 2002 are met. Accordingly, the invention provides for a method comprising at least the following steps:

- placing one or more containers in a sealable space;

- increasing the temperature in the sealed space to a maximum predetermined temperature;

- lowering the oxygen content ; and

- regulating the air humidity of the heated air or air to be heated. Increasing the temperature takes place by heating the air in the sealed space, in which the air temperature in the sealed space, in at least one container and the temperature of a product in the container and/or of the packaging material or the transport material is measured. Apart from bringing the product at a desired temperature, it is also necessary to bring the packaging materials, and more particularly the wooden pallets on which the products are mostly positioned, at the desired temperature. The vermin to be eliminated can be present within the wood of the pallets so that these should be heated to the core of the beams to the desired temperature. In eliminating said vermin it is essential that the desired temperature is high enough and that it will also be maintained for a sufficiently long period of time. The common insects can be eliminated relatively easy by an elevated temperature, however, for eliminating the larvae and especially the eggs of the insects it is essential to apply a higher temperature and maintaining it for a longer period of time. According to the invention, the temperature in the sealed space is brought to 60-80°C in order to effect a temperature of 5β-60°C in the product and the packaging and transport materials. Preferably, this latter temperature is within a range of 56-57°C. With such a temperature, one can be sure that also the eggs of the insects will be des- troyed if the treatment continues for a sufficient period of time . In order to prevent the products from oxidizing at such an elevated temperature, according to another elaboration it is provided for, that the oxygen content of the air is reduced to 0,5-5% and preferably to about 1% before heating the remaining gas mixture within the sealed space . Such an oxygen percentage will also prevent oxidization of products which are especially sensitive to it, such as peanuts, cocoa beans, coffee, tobacco, rice and similar products. Also, it is provided for that the air humidity will remain between 45-75% by adding water to the heated air. This prevents the products from drying out, which is highly important with food products in particular. The invention is aimed at carrying out the elimination of vermin according to the method indicated on a large scale, that is, with the cargo of a number of containers in one treatment, without removing the cargo from these containers. To this end, the invention provides for a device for conditioning a sealable space in this way, in which the device comprises a combustion cylinder, a gas supply pipe having a reduction member incorporated in it, an air supply pipe having a supplying member for pressurized supply of combustion air, a catalyst in or immediately behind the combustion cylinder, and subsequently a cooling member for cooling the combustion gases and a dehumidifier for removing the water component from the combustion gases. The cooling member is necessary for lowering the high temperature of the gas mixture obtained in combustion to a temperature in or near the range of the lower temperature required for the method. The gas mixture leaving the cooling member having a much lower temperature than the original temperature of the combustion gases is led through an air dehumidifier and consecutively through an active carbon filter in order to catch any toxic substances as well as smells, before supplying the modified gas mixture thus produced to the sealed space. The function of the active carbon filter is specifically important with eliminating vermin in foodstuffs. Said gas mixture thus pretreated and brought in the sealed space has a temperature which is too low for carrying out the method. According to a further elaboration, one or more heating members mounted in a sealed space are provided for bringing the gas mixture to the desired temperature and maintaining it at this temperature. Such a heating member substantially comprises a heat exchanger connected to an external heat source and a fan for controllably directing said gas mixture in said sealed space along said heat exchanger. In this way, the temperature can be controlled quickly and within a small range. Further, the device is provided with an operating system for operating at least the gas and air supply to the combustion cylinder is operated, the operation of the dehu- midfier and the pressurized supply of the final gas mixture to the sealed space. At the same time means for determining the oxygen content of said gas mixture being fed under pressure to said sealed space are provided, and further means for returning a portion of the gas mixture into the air supply to the combustion cylinder are provided. With this feedback system, the oxygen content can be maintained at an almost constant value . Further, one or more temperature sensors are provided in the sealed space which are coupled to the operating system, said operating system being arranged for controlling the temperature in the sealed space within a predetermined range on the basis of the measured temperature. Here, one or more temperature sensors in the product or the packaging or transport materials are coupled to said operating system, in which the temperature of the gas mixture brought into the sealed space can be adjusted on the basis of the measured temperature. Measuring the temperature in product and e.g. the supporting pallet may not be equally important in all cases. In case of a cargo comprising metal parts it is much more important to know what the temperature in the core of the wooden beams of a pallet is than what the exact temperature of the metal parts is. The invention also incorporates a sealable space being arranged for carrying out the method, in which said sealable space is practically air tight, the walls are provided with an insulating material and the space is dimensioned such that it can accommodate at least a number of sea containers simultaneously. Additionally, one or more heating members are mounted in the sealable space, mainly comprising a heat exchanger connected to an external heat source and an air displacing member, such as e.g. a fan. With said heating members, the gas mixture in the sealable space is maintained at the desired temperature. Additionally, one or more separate air fans have been mounted, at least one of them being freely directable, which cause the heated gas mixture to be circulated evenly through the whole of the containers. Preferably, to this end, further means for positioning and directing at least one air fan are provided, as well as preferably a remote control for the remote control of said means. Preferably, the fans are arranged such, that the heated gas mixture will be blown into the containers at their top sides. Further, the sealable space mounts sensors for measuring at least one or more of the variables temperature, oxygen content and air humidity. In order to bring the sea containers into the sealable space with ease, according to a further elaboration of the invention a movable chassis is provided onto which the containers can be mounted and a guiding system for said movable chassis . According to a first embodiment, the guiding system comprises a set of rails having substantially plane rail surfaces, and connecting to said rail surfaces at least one downwardly extending flank, said rails having been mounted in the loadbearing floor and the rail surface being at equal height with said loadbearing floor and a recess extending alongside the rails being arranged adjacent the downwardly extending flank in the loadbearing floor. In this embodiment, a standard rail type can be employed, however, a removable sealing of the recess must be provided at the level of the entrance of the sealable space. According to a second embodiment, the guiding system comprises a set of rails having substantially plane rail surfaces and one flank connecting to each of said rail sur aces. Further it has been provided for that the rails have been fitted in a loadbearing floor, in which the rail surface ends at equal level with the floor and in which the raised flanks have an interruption at the entrance of the sealable space. This last feature is necessary in order to obtain a proper sealing of the sealable space. The guiding system permits properly sealing off the space since the loadbearing floor has a practically plane surface at the entrance . The movable chassis is arranged for being able to transport a number of containers simultaneously, in which a possible configuration comprises e.g. a total of 8 containers divided in 4 groups of 2 stacked containers each. The great advantage of such a movable chassis is that the trailers on which the containers are transported need not be employed so that they are available for other tasks and that the movable chassis can be entirely adapted to the specific eliminating operations. A movable chassis is provided with spaced-apart wheel sets, said wheels being suited to roll on the rails, such that at least the wheels of two wheel sets will always contact the raised flanks of the rails. With a movable chassis having a length for 8 containers according to the configuration indicated above, this will always be the case so that wheels at the interruption of the rails will also remain in the proper track. The containers or the groups of stacked containers are placed on the movable chassis in spaced-apart relationship so that there is sufficient space for being able to open the container doors. According to another elaboration, vertically adjustable platforms are mounted between the containers or groups of containers, said platforms firstly serving to get at the proper height for being able to open the doors of the uppermost container. Further, the vertically adjustable platforms can serve as mounting support for a fan, in which the fan serves for blowing the hot air within the sealable space into the top of a lower container. Fans for blowing the hot air within the sealable space into the top of a lower container are adjustably mounted in the sealable space, so that they can be brought into the proper position after the movable chassis has been moved into the sealable space. Preferably, positioning these fans takes place from the adjustable platforms. The invention is further explained by way of the example given in the drawing, in which: fig. 1 illustrates an arrangement of two halls containing sealable spaces or cells suitable for carrying out the method according to the invention; fig . 2 shows a view of a movable chassis with containers; fig - 3 shows a rear view of a movable chassis with containers; fig . 4 illustrates details of a first embodiment of wheel and rail; fig . 5 illustrates details of a second embodiment of wheel and rail; fig - 6 illustrates schematically the design of the device for carrying out the method; and fig . 7 illustrates schematically the part of the device for modifying the low-oxygen gas mixture to be used. Fig. 1 illustrates a first, large hall 1 in which pairs of sealable spaces or cells 2 are arranged, each comprising two cells 3, 4. Each cell 3, 4 shows a movable chassis 5, its lenght and width being such that 4 pairs of 2 stacked containers, 8 containers in total, can be mounted on it. In every cell 3, 4, next to chassis 5, a gangway 6 is kept free, which is used for the positioning of one or more air heating members and further serves for giving personnel room to be able to open the doors of all individual containers after a chassis with containers has been brought into a cell 3, 4. The free space of gangway 6 is also necessary for mounting apparatus such as e.g. parts of measuring and control systems and the movable or stationary fans. The fans serve for displacing the hot air in the cell space quickly and to the farthest corners of the containers . Each cell 3, 4 is provided with a properly sealing door 7 at the front side 8 of the cell. The movable chassis 5 is located on a pair of rails 9 extending across the length of a cell to such a distance beyond the hall 1 that there is enough space to be able to load said chassis 5. For loading said chassis 5 with containers, any harbour apparatus or similar apparatus suitable for that purpose can be employed. A second, smaller hall 11 having cells 13, 14 likewise arranged in pairs and offering room to movable chassis 15 is located adjacent the first hall 1. Said cells 13, 14 and the chassis 15 arranged therein have half the capacity of the large cells 3, 4 and the chassis 5 accommodated therein, therefore for not more than 4 containers. The rails 16 for the chassis 15 accordingly extend across smaller distance beyond said hall 11. The arrangement with a multiplicity of large cells 3, 4 and a number of smaller cells 13, 14 provides the opportunity of being able to react flexibly on a varying supply or to perform specialist treatments which do not occur very frequently. With this latter, one can e.g. think of gassing, de-gassing and specialistic measurements. Fig. 2 illustrates a side view of a shortened movable chassis 15, on which four containers 17 have been mounted. If necessary, said containers 17 will be fixed on the top surface 18 of the chassis 15 with knowm locking means engaging the standardized angular points of containers. The top surface 19 leaves enough room to be able to situate the pairs of containers spaced-apart and spaced from one of the outermost ends of the chassis 15. This is necessary to be able to open the doors of container 17. In order to be able to reach the doors of the upper containers 17 without difficulty, vertically adjustable platforms 18 have been mounted at the level of the free spaces on the chassis 15. The platforms 18 are provided with a shear lift system 20, by which the platforms 18 can be moved from a lowermost position, in which the top surface 19 is preferably aligned with the top plane of chassis 15, to an uppermost position, in which the top plane 19 of the platform 18 can be brought to a height which is high enough to reach the doors of the upper container in case of stacking of the highest containers. The maximum height of a platform 18 is also such, that fans secured in the upper part of the cell can be brought to a desired position by hand. A fan 21 is mounted at the bottom side of the platform 18, said fan blowing into the upper space of the lower container when said platform 18 is in the uppermost position. Further, additional fans 21' are mounted at the bottom side of the chassis 15 which should provide for a uniform distribution of the hot air from the gangway 6 to the opposite side of the cell. Connection of fans 21, as well as the shear lifts 20 and control and measurement systems occurs with one or more connecting cables and connecting lines after the chassis 15 in the cell has been brought in a parking position. Chassis 15 is provided with a driving member not further indicated in the drawings, which is an electric drive or an electrically driven hydromotor, for example. The electric power source can be designed in a simple way with a cable which can be wound from and onto an automatic reel being continuously connected to the chassis 15. There, the reel is fastened to the end wall in the cell. With two coupled chassis, the front chassis 15 will be provided with a driving member and the cable will obviously be connected to the front chassis 15. The control occurs preferably with the help of a manually operated control module in which, for safety reasons, the person operating the module walks along with the chassis for monitoring. In the rear view of fig. 3 it is clearly visible that through an axle 23 the movable chassis 15 stands on relatively small wheels 22 situated within the outer circumference of the chassis. The diameter of the wheels is preferably kept small in order to avoid much unused space below the movable chassis 15. Fig. 4 illustrates a first embodiment of a wheel 22 and rail 16. The rail 16 is of a common type mounted up to the rail surface 23 in the loadbearing floor 24. A recess 25 is provided at one side of the rail in order to have room for the circumferential flange 26 of the wheel 22 that will engage the flank 27 of the rail 16. Connecting to the flank 27 a filling piece 28 is fixedly mounted in the loadbearing floor 24 for giving the recess 25 a rectangular shape. This allows for providing an easily removable further filling piece at the doors 7 of the sealable space. Fig. 5 illustrates a second embodiment of a rail 29 and a wheel 30, in which the rail 29 is provided with a raised flank 31. The rail 29 is fitted in the concrete loadbearing floor 24 in which the rail surface 32 is almost aligned with the top surface of the concrete loadbearing floor 24. The raised flank 31 provides for, together with a corresponding flank on the accompanying other rail, that the wheel pairs 22 will remain on the rails. Wheel 30 is provided with a bevel 33 so that the contact surface with said raised flank 31 remains limited. In this example, the flanks 31 are mounted at the outer side of the rail, which of course can occur just as well at the inner side of the rail. At the doors 7 at the front side of a cell the flanks 31 of a rail 29 are interrupted as a result of which an almost plane surface is obtained at the doors. Therefore, the doors 7 can simply connect to the loadbearing floor in a sufficiently sealing way in their closed positions. The interruption of the flanks 31 extends only across a relatively small length and there are always a sufficient number of wheel pairs engaging the rail and accompanying flank 31 for being able to keep a chassis 15 on the rails 29. Fig. 6 provides a schematic outline of the complete system. A container with a load 34 has been placed in a sealed-off cell 3. Through line 35, cell 3 is connected to a member 36 where the low-oxygen gas mixture required for the treatment is generated. On starting a treatment, the still oxygen-rich air mixture in cell 3 is returned to member 36 through the return line 37 as long as will be necessary for bringing the final gas mixture within cell 3 at the desired low oxygen content . The heat released in the process within member 36 is supplied to a heating system 38 by which the necessary facility rooms are heated. The low-oxygen gas mixture in the cell 3 is brough at the temperature desired for the treatment with the help of heating members 39, substantially comprising a heat exchanger 40 and a fan 41 for feeding the low-oxygen gas mixture across the heat exchanger. The heat exchanger 40 is supplied from a heat source 42, in which the heat source 42 can be a steam boiler or a cylinder with thermal oil, for example. The heat source is further provided with a fuel supply 43 and a discharge 44 for combustion gases. Through measuring and control connections 46, an operating system 45 provides for operation of all processes important for the treatment, either directly or by intervention of a further sub-operating system. Fig. 7 provides a schematic outline of the system representing the member 36 for generating the low-oxygen gas mixture. The system comprises a combustion cylinder 47 having a catalyst not further indicated in the drawing, a gas supply line 48 and an air supply line 49. In said gas supply line 48, a first stop valve 50, a gas pressure switch 51 and a filter 52 are mounted at the connection to the gas mains. Subsequently, a main cock 53 operated by the control system 54 is incorporated in the gas line, whereupon the line is divided in a part for a pilot flame of the combustion cylinder 47 having a reducing portion with an operated valve 55 and a needle valve 56 and a part for the main burner having a reducing portion with an operated valve 57 and a needle valve 58. An air supply fan 59 and an air pressure switch 60 are incorporated in the air supply line. The air supply fan 59 is operated from the control system 54. The gas supply valves 55, 57 are operated through a separate combustion control unit 61. This combustion control unit 61 provides for control of the entire combustion process, with the control unit 54 only producing a signal for starting/stopping the combustion. The catalyst in the combustion cylinder 28 provides for a best possible bond between gas molecules and free oxygen molecules. After passing the catalyst, the then existing gas mixture has a temperature which is still much too high to undergo further conditioning treatments and/or to be used for the vermin control purposes. Thus, the gas mixture is first cooled through a water cooler 62. The warm cooling water released therein and the cooling water released from the combustion cylinder is preferably used for heating the office or working spaces belonging to the complex. The water cooler 62 is followed by a dehumidifying member 63 by which the water component is removed from the combustion gases leaving a low-oxygen gas mixture. Before this gas mixture is supplied to the sealable spaces or cells 3, 4; 13, 14 it moves through an active carbon filter 64 for removing any smells and toxic substances. Through line 35, pressurized gas mixture 64 coming from the carbon filter 64 is brought into the cells by fan 65. The return flow 37 coming from cell 3 connects to the air supply line 49 with an operated valve 66 being incorporated in the return line 37. The valve 66 is operated from an oxygen analyzing member 67, which determines the oxygen content in the gas mixture supplied to the cells. If case of an oxygen content which is too high, a part of the gases will be returned to the air supply to the combustion cylinder 47. The central operating system 45 monitors and controls temperature and air humidity in both the cells and the products to be treated. On the basis of these data and the entered parameters, the combustion process is correspondingly adjusted through the operating system. Practice has shown, that in a duration of 12-24 hours a complete cargo with the accompanying packaging materials and wooden pallets can be brought at the desired temperature of 56°C to the core. After that, the temperature should be maintained for a certain time duration, so as to truly kill all insects larvae and eggs . The average treatment period of a cell with 8 containers will be approximately 48 hours.

- claims -

Claims

C L A I M S

1. Method for eliminating vermin in containers and in the cargo located therein, comprising at least the following steps :

- placing one or more containers in a sealable space;

- increasing the temperature in the sealed space to a maximum predetermined temperature ;

- lowering the oxygen content; and

- regulating the air humidity of the heated air or air to be heated.

2. Method according to claim 1, characterized in that heated air is brought into the sealable space in which the air temperature in the sealed space, in at least one container and the temperature of a product in the container and/or the packaging material or the transport material are measured.

3. Method according to claim 2, characterized in that the air in the sealed space is brought to a temperature of 60-80°C.

4. Method according to claims 2-3, characterized in that the air temperature is controlled in such a way, that the temperature in the product reaches a temperature in the range of 56-60°C.

5. Method according to claim 4, characterized in that the temperature in the product is maintained within a range of 56-57°C.

6. Method according to claim 1, characterized in that the oxygen content of the heated air is reduced to 0,5-5%.

7. Method according to claims 1-6, characterized in that the air humidity of the heated air is controlled such that it will remain within a range of 45-75% air humidity in the sealed space.

8. Method according to claims 1-7, characterized in that after a product has spent a predermined time in the sealed space under predetermined conditions, the oxygen content in the sealed space is brought at or almost at the level in the outside air prior to opening said sealed space.

9. Device for heating and conditioning air according to one or more of the preceding claims, characterized in that it comprises a combustion cylinder, a gas supply pipe having a reduction member incorporated in it, an air supply pipe having a supplying member for pressurized supply of combustion air, a catalyst in or immediately after the combustion cylinder, and connecting to said combustion cylinder, a cooling member for cooling the combustion gases and a dehumidifier for removing the water component from the combustion gases, respectively.

10. Device according to claim 9, characterized in that a carbon filter has been provided, in which the gas mixture coming from the dehumidifier is led through the carbon filter.

11. Device according to claims 9-10, characterized in that one or more heating members for heating the gas mixture brought in the sealed space have been mounted in a sealable space.

12. Device according to claims 9-10, characterized in that a heating member substantially comprises a heat exchanger connected to an external heat source and a fan for directing said gas mixture within the sealed space control- lably along said heat exchanger.

13. Device according to claims 9-12, characterized in that it is provided with a control system for controlling at least the gas and air supply to the combustion cylinder is controlled, the operation of the dehumidfier and the pressurized supply of the final gas mixture to the sealed space.

14. Device according to claim 13, characterized in that said control system is provided with means for determining the oxygen content of said gas mixture being fed under pressure to said sealed space are provided, and further means for returning a portion of the warm gas mixture into the air supply to the combustion cylinder.

15. Device according to claims 9-14, characterized in that one or more temperature sensors are provided in the sealed space which are coupled to the control system, said control system being arranged for controlling the temperature in the sealed space within a predetermined range on the basis of the measured temperature.

16. Device according to claim 15, characterized in that one or more temperature sensors in the product or the packaging materials and/or pallets are coupled to said control system, in which the temperature of the pressurized gas mixture brought into the sealed space can be controlled within a predetermined range on the basis of the measured temperature .

17. Device according to claims 9-16, characterized in that one or more air humidity sensors in the sealed space are connected to the control system and that it is arranged to control the air humidity of the pressurized gas mixture brought into said sealed space on the basis of the measured air humidity.

18. Device according to claim 17, characterized in that one or more air humidity sensors in the product are connected to the control system and that the control is adapted to a minimum humidity of the product.

19. Sealable space to be used in combination with a device according one or more of the preceding claims, characterized in that said sealable space is practically air tight, the walls are provided with an insulating material and the space is dimensioned such that it can accommodate at least a number of sea containers simultaneously.

20. Sealable space according to claim 19, characterized in that one or more heating members are mounted in said sealed space, substantially comprising a heat exchanger connected to an external heat source and air displacement member, such as a fan, for example.

21. Sealable space according to claim 20, characterized in that one or more fans are arranged in said space, with least one of them being freely directable.

22. Sealable space according to claim 21, characterized in that means for positioning and directing at least one air fan are provided, and further a remote control for the remote control of said means .

23. Sealable space according to claims 19-22, characterized in that one or more sensors are arranged in said sealable space for measuring at least one or more of the variables temperature, oxygen content and air humidity.

24. Sealable space according to claims 19-23, characterized in that the sealable space is a fixed arrangement in which a guiding system is provided in order to guide a movable chassis, intended for accommodating one or more containers, into and out of said space.

25. Sealable space according to claim 24, characterized in that the guiding system comprises a set of rails having substantially plane rail surfaces, and, connecting to said rail surfaces, at least one downwardly extending flank.

26. Sealable space according to claim 25, characterized in that said rails have been mounted in the loadbearing floor and the rail surface is at equal height with said loadbearing floor and a recess extending alongside the rails being arranged adjacent the downwardly extending flank in the loadbearing floor.

27. Sealable space according to claim 26, characterized in that a filling piece has been provided for filling up the recess at the entrance to the sealable space.

28. Sealable space according to claim 27, characterized in that said filling piece comprises a first filling piece fixedly mounted against the rail and filling-up the flank across the full depth of the recess and a second removable filling piece filling-up the remaining part of the recess.

29. Sealable space according to claim 24, characterized in that the guiding system comprises a set of rails having substantially plane rail surfaces and one raised flank connecting to each rail surface.

30. Sealable space according to claim 29, characterized in that the rails have been fitted in a loadbearing floor, in which the rail surface ends at equal level with the floor and in which the raised flanks have an interruption at the entrance of the sealable space.

31. Movable chassis for moving containers into and out of the sealable space according to one or more of the preceding claims, characterized in that the movable chassis has a substantially flat top surface which is provided with means for fixedly mounting said containers .

32. Movable chassis according to claim 31, characterized in that spaced-apart wheel sets have been provided, said wheels being suited to roll on the rails, such that at least the wheels of two wheel sets will always contact the raised flanks of the rails.

33. Movable chassis according to claims 31-32, characterized in that one or more vertically adjustable platforms have been mounted on the top surface .

34. Movable chassis according to claim 33, characterized in that at least one adjustable platform is mounted on a shear lift.

35. Movable chassis according to claims 33-34, characterized in that at least one fan has been mounted on and/or below a platform, said fan being directed such, that it blows air into an opened container.

36. Movable chassis according to claims 31-35, characterized in that one or more fans have been mounted at the bottom of at least one chassis, in which they have been positioned for effecting an air stream substantially transverse to the longitudinal direction of said chassis.

37. Movable chassis according to claims 31-36, characterized in that the chassis or the frontmost chassis of two coupled chassiss is provided with a driving member.

38. Movable chassis according to claim 37, characterized in that the driving member is an electric drive or an electrically driven hydromotor .

39. Movable chassis according to claim 38, characterized in that a cable mounted on an automatic reel has been provided for feeding said driving member, said reel being secured to the end wall of a cell with a first end of the cable being connected to a power source and the second end to the driving member.