WO2012107518A2

WO2012107518A2 - System for cooling medium introduction into a container

Info

Publication number: WO2012107518A2
Application number: PCT/EP2012/052208
Authority: WO
Inventors: Peter DYCKMANS; Rik TIMMERMANS; Jan Vansant; Joanna GÓRZYNSKA; Eryk REMIEZOWICZ; Règis HAJEK; Wojciech LAUTEROWSKI
Original assignee: Acp Belgium N.V.
Priority date: 2011-02-09
Filing date: 2012-02-09
Publication date: 2012-08-16
Also published as: BE1020015A5; NL1039372C2; EP2673575B1; FR2971330B1; DE102012002403A1; NL1039372A; FR2971330A1; EP2673575A2; DE102012002403A9; ES2829553T3; PT2673575T; WO2012107518A3; PL398058A1

Abstract

The present invention provides a system comprising a cassette, a filling station and a loading pistol for cooling products such as foodstuff in a container. The cassette of the present invention is suitable to contain a CO₂ cooling medium, such as liquid CO₂, whereby said cassette comprising one inlet for the introduction of the CO₂ cooling, medium and one outlet for the withdrawal of gaseous CO₂ formed while exposing the CO₂ cooling medium to atmospheric conditions. The cassette is characterized in that the inlet and the outlet are spatially separated and are both provided with magnetic coupling means.

Description

SYSTEM FOR COOLING MEDIUM INTRODUCTION INTO A CONTAINER

Field of the invention

The present invention relates to the field of filling insulated containers, in particular transport insulated cooling containers with a cryogenic medium. More in particular, the present invention relates to a system, devices and methods for the introduction of a cryogenic medium into an insulated container.

State of the art

Low temperatures have to be maintained during transport and/or storage of products, namely food or perishables, inside insulated containers. Therefore, systems and devices were developed wherein the dry ice snow is created, by expansion of liquid C0₂ in special cassettes, placed in containers. The expansion of liquid C0₂ results also in gaseous C0₂ production in the cassette. Said gas is preferably removed from the cassette in order to avoid any mechanical stress due to the created C0₂ gas volume.

EP 1 326 046 discloses a system for filling a cooling container with a cryogenic medium. The system comprises a coupling device and a countercoupling element having each at least one extraction opening for gaseous C0₂ withdrawal. The extraction openings are brought into flow connection with the corresponding extraction openings provided in the countercoupling element so that an extraction line is created from the cooling container into the coupling device. The system implies that special cassettes have to be used which limits the user's freedom. The gas removal system is not tight enough to ensure sufficient purity of recovered C0₂, thereby making reliquefaction possible. The recovered gas is released into the atmosphere which has negative economic and environmental consequences.

EP 1 291 594 presents a module for injection of liquid carbon dioxide into a refrigerating module assigned to a refrigerating container. The module is massive enough to incorporate means necessary to inject liquid carbon dioxide into one of two openings of the cassette and a removal system for gaseous C0₂, thereby solving the problem of emission of gaseous C0₂. The filling process is coupled with gas removal process. However, the significant size of the module makes it difficult to operate. In working mode, the suction cups are placed in front of the refrigerating module. The connection between the refrigerating module and the suction cups is achieved by activation of vacuum generating means provided in the suction cups. This system cannot ensure a pure gaseous C0₂ recuperation as the described connection is not airtight. Moreover, the means for supplying liquid C02 and for withdrawing the carbon dioxide gas are assigned to a common housing. These systems allow only for usage of one module for one cassette at once, thereby slowing down the filling process.

EP 0 823 600 discloses a cassette being a two-part arrangement consisting of an L- shaped reservoir and the upper part of the container. A part of the cassette is dedicated to the separation and evacuation of the gas. The cassette is provided with a feed channel and a suction channel. A one-piece cassette will be simpler, more robust, less prone to gas leakage, and less vulnerable to small differences in container size. One cassette system gives the customer the choice of a container and is safer during the operation, as a one-piece cassette is less prone to be pushed out from the container during injection. Moreover, there is no indication regarding the connection between the suction channel and the suction means during the removal of gas. The gas removal system is not tight enough to ensure sufficient purity of recovered C0₂, thereby making reliquefaction possible.

In all the cassettes listed above, the gaseous C0₂ is escaping out of the cassette. This is due to the fact that the upper surface of these cassettes is made of a grid or a fabric that is permeable to gas. Hence, gas escapes in the environment which is dangerous for the environment and for the working staff.

The developed systems present several other disadvantages such as being operationally complicated with large equipment devices. The loading stations in a fixed position and the containers have to be brought to the station location to be loaded, which requires additional manpower. Moreover, if the distribution centre that uses the dry ice loading system is large, a need arises to install several loading stations, which severely increases the investment cost. Another drawback is the fact, that today's systems are strictly bound to one specialised kind of drawer. Due to mergers and acquisitions, companies often have several types of containers. Replacing them all in order to adjust to the container loading systems is a significant cost that should be avoided. The aim of the present invention is to provide a solution to overcome at least part of the above mentioned disadvantages by providing an improved cassette, an improved loading pistol, an improved filling station and system. Further details of the invention are provided by the description hereunder and the appended claims and figures. Summary of the invention

In a first aspect, the present invention provides a cassette for cooling products such as foodstuff in a container, suitable to contain a C0₂ cooling medium, such as liquid C0₂, whereby said cassette comprising one inlet for the introduction of the C0₂ cooling medium and one outlet for the withdrawal of gaseous C0₂ formed while exposing the C0₂ cooling medium to atmospheric conditions. The cassette is characterized in that the inlet and the outlet are spatially separated and are both provided with magnetic coupling means. In a preferred embodiment, the inlet and the outlet of the cassette are cylindrical channels through a wall of the cassette.

In a preferred embodiment, the lid of the cassette is gastight.

In a preferred embodiment, longitudinal parallel corrugated channels are provided in the lid of the cassette. In a further preferred embodiment, the corrugated channels have in cross sectional view a circular, rectangular, triangular, conical, inverted conical or inverted frusto-conical shape, preferably a frusto-conical shape.

In a preferred embodiment, the cassette comprises two adjacent cooling chambers separated by a separation element and at least one collection chamber in front of said cooling chambers for collection of gaseous C0₂.

In a preferred embodiment, the separation element of the cassette is at least partly hollow and is connected at one end to the inlet of the cassette. In a further preferred embodiment, the separation element of the cassette is provided with at least two openings, each opening is in fluid connection with each cooling chamber of the cassette.

In a preferred embodiment, the cassette comprises a separation filter covering the cooling chambers of the cassette and positioned under the lid of the cassette, said separation plane is permeable to gaseous C0₂.

In a preferred embodiment of the invention, a predetermined quantity of liquid C0₂, sufficient to fill at least one cooling chamber is suitable to be injected in the cassette.

In a second aspect, the present invention provides a filling station for the introduction of a C0₂ cooling medium such as liquid C0₂ and suitable to be used with a cassette of the invention, said filling station comprising a control cabinet provided with at least one loading pistol for the injection of the C0₂ cooling medium in the cassette and at least one suction head for the removal of gaseous C0₂ from the cassette. The filling station is characterized in that, the loading pistol and the suction head are separate and independently operable entities. In a third aspect, the present invention provides a loading pistol suitable for the introduction of a C0₂ cooling medium in a cassette of the invention. The loading pistol is characterized in that, it is provided with an outlet containing separate piping and outlet openings, said loading pistol is suitable to be introduced, through the inlet, in the separation element of the cassette. In a preferred embodiment, a heating element is provided in said loading pistol outlet.

In a fourth aspect, the present invention provides a system comprising a cassette of the invention, a filling station of the invention and a loading pistol according to the present invention for cooling products such as foodstuff in a container.

In a fifth aspect, the present invention provides a method for cooling products such as foodstuff in a container comprising the steps of connecting a loading pistol to a cassette for the introduction of a C0₂ cooling medium and connecting a suction head to said cassette for the withdrawal of gaseous C0₂ formed while exposing the C0₂ cooling medium to atmospheric conditions, whereby said suction head and said loading pistol are separately connected to the cassette and are magnetically connected to the cassette.

In a preferred embodiment of the method, the withdrawal of gaseous C0₂ and the introduction of the C0₂ cooling medium are separately, simultaneously and/or subsequently performed.

The cassette of the present invention presents several advantages. The cassette allows the withdrawal of essentially pure gaseous C0₂ without increasing pressure within the cassette and without entraining solid C0₂ produced in liquid expansion process. Hence, reliquefaction of the gaseous C0₂ emitted during liquid C0₂ injection is possible. The cassette and system of the invention increase the efficiency of use of the cold gaseous C0₂ produced during decompression of liquid C0₂. This leads to a cost reduction.

The flow of gaseous C0₂ is precisely guided in the cassette of the present invention, therefore facilitating design of light cassette, which is reinforced only where it is required. The elements of the cassette are not moved due to mechanical shocks resulting from transport process, liquid C0₂ expansion process and other processes. The cooling chambers of the cassette are separated and no solid C0₂ will be transferred to an inappropriate chamber due to mechanical shocks resulting from transport process, liquid C0₂ expansion process and other processes. Moreover, some of the elements of the cassette are additionally reinforced in order to eliminate the need for maintenance. Hence, the cassette offers a high safety level to the user and to the environment. The cassette can be further upgraded with heat exchange elements to facilitate maintaining of additional temperature ranges in the isothermal container.

The cassette of the present invention is a closed cassette. It is gastight and no gaseous C0₂ is capable of escaping out of the cassette through its lid. The cassette is equipped with additional technical solutions eliminating most of the maintenance typical for other cassettes. The cassette ensures mechanical ruggedness and facilitates gas removal, without being a large and massive cassette. A cassette of significant size would mean a reduction of space for the transported goods, an increase in the mass of the container leading to more difficult handling and a more difficult handling of the cassette itself. The cassette of the present invention can be a part of a system for injection of liquid C0₂.

Description of the figures

Figure 1: side cross section view of an exemplary embodiment of the invention and its important elements.

Figure 2: isometric view of an embodiment of the invention together with an isothermal container.

Figure 3: schematic cross section view of an exemplary embodiment of the invention presenting the possibility to connect three independent filling systems to one control cabinet.

Figure 4: schematic cross section view of an exemplary embodiment of the invention presenting the possibility to fill several cassettes at once.

Figure 5: working mode of the phase separator, which allows for removal of gaseous C0₂ from the liquid C0₂ line.

Figure 6: exemplary embodiment of the heating of the outlet of the snowgun for liquid C0₂ injection.

Figure 7: exemplary embodiment of the gas-tight connection between the cassette and the suction head for withdrawal of gaseous C0₂.

Figure 8: isometric view of an exemplary way of cassette filling with solid C0₂.

Figure 9: exemplary way of functioning of the invention, where the heat absorption capacity of gaseous C0₂ formed during decompression is used to cool down the fresh air flowing into the distribution centre.

Figure 10: exemplary way of functioning of a distribution centre as a whole. Figure 11: schematic side cross section view of a particular embodiment of the loading pistol.

Figure 12: schematic cross section view from above of a particular embodiment of the outlet of the loading pistol.

Figure 13: schematic cross section view from above of a particular embodiment of the cassette with the outlet of the loading pistol mounted within it.

Figure 14: schematic cross section front view of a particular embodiment of a container during transport.

Figure 15: schematic isometric view of a particular embodiment of the cassette.

Figure 16: schematic isometric exploded view of a particular embodiment of the loading equipment with container and cassette.

Figure 17: another schematic isometric view of a particular embodiment of the cassette

Figure 18: exemplary embodiment of the gas-tight connection between the cassette and the snowgun for injection of liquid C0₂.

Figure 19: schematic isometric view of a particular embodiment of isothermal container with the cassette, loading pistol and suction head.

Figure 20: schematic view from above of a particular embodiment of the cassette with its lid and separation plane removed.

Figure 21: schematic isometric view of a particular embodiment of the cassette with its lid removed.

Figure 22: schematic cross section view from behind of a particular embodiment of the cassette.

Figure 22 a: a magnified schematic cross section view of one corrugated channel of the cassette.

Figure 23: schematic cross view from side of a particular embodiment of the cassette.

Detailed description of the invention

The present invention relates to a system for injecting liquid C0₂ into a cassette. The system and devices of the present invention comprise a filling station having at least one liquid C0₂ loading pistol and at least one C0₂ gas suction head, at least one cassette wherein a determined quantity of liquid C0₂ is suitable to be injected. The different element of the system of the present invention are detailed hereunder and in the accompagnying figures. Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

As used herein, the following terms have the following meanings:

"A", "an", and "the" as used herein refers to both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compartment" refers to one or more than one compartment.

"About" as used herein referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of +/- 20% or less, preferably +/-10% or less, more preferably +/-5% or less, even more preferably +/-1% or less, and still more preferably +/-0.1% or less of and from the specified value, in so far such variations are appropriate to perform in the disclosed invention. However, it is to be understood that the value to which the modifier "about" refers is itself also specifically disclosed.

"Comprise," "comprising," and "comprises" and "comprised of" as used herein are synonymous with "include", "including", "includes" or "contain", "containing", "contains" and are inclusive or open-ended terms that specifies the presence of what follows e.g. component and do not exclude or preclude the presence of additional, non-recited components, features, element, members, steps, known in the art or disclosed therein.

The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints.

The expression "% by weight" (weight percent), here and throughout the description unless otherwise defined, refers to the relative weight of the respective component based on the overall weight of the formulation.

The terms "drawer" and "cassette" are used herein as synonyms.

The terms "loading pistol", "injection pistol", "pistol" and "snowgun" are used herein as synonyms.

The terms "injection system" and "filling station" are used herein as synonyms.

The terms "aperture", "hole" and "opening" are used herein as synonyms.

The terms "separation plane" and "separation filter" are used herein as synonyms referring to two metal grids and of a separation fabric placed in the cassette of the present invention.

Injection system Fig. 1 presents a schematic side cross section view of the control cabinet 1 itself and of and its important elements. The supply of liquid C0₂ to the snowgun 2 as well as withdrawal of gaseous C0₂ with the suction head 3 is also shown.

It is advantageous to insulate the control cabinet 1 as it decreases the heat losses of liquid C0₂, thereby increasing the efficiency of the equipment. Insulation also increases the comfort of the operator, as the large surface of the cabinet will have temperatures close to ambient. As there are several types of cassette 5 on the market, each requiring its own type of snowgun, the user may choose his own type of snowgun, suitable to his needs. It is possible that the user will alternatively use several types of snowguns in order to supply all the types of the drawers he possesses. The choice of coupling of the snowgun 2 to the cassette 5, allowing for easy connection process, but preventing disconnection during loading process can be made of any type known to a person skilled in the art, e. g. mechanical or magnetic coupling. The snowgun may be equipped with a starter for the loading process, but the starter is not a necessary part of the snowgun, as the starter can be placed in the control box 6. Therefore the starter is not shown in detail.

On fig. 6 a schematic of an embodiment of the snowgun 2 is presented. A heating element 21 is provided in order to prevent snowgun freezing, which in turn could make it impossible to withdraw the snowgun after completion of the injection. The heating element 21 warms the snowgun outlet 22. The heating element 21 is a resistance wire mounted into snowgun outlet 22. The wire is powered by electric cable 24, while the cables 25 running through the snowgun grip 26 are not meant to heat it, but only to conduct electricity.

On fig. 7 a schematic embodiment of connection of suction head 3 with cassette 5 is presented. In this example the cassette 5 is equipped with magnet 51, in which a ring 52 is grooved. An identical magnet 53 is mounted on suction head 3 and in its groove an O-ring gasket 54 is placed. The strength of such connection is provided by the magnets 51 and 53, while the gasket 54 is meant to provide tightness. The gasket is made of any rubbery material that is not brittle at a temperature lower than -80°C.

The gasket material is selected from the list comprising gasket paper, rubber, ethylene propylene diene monomer, ethylene propylene diene monomer nitrile, buna, neoprene, flexible graphite, grafoil, aflas, kalrez, viton, silicone, metal, mica, felt and plastic polymer such as Teflon® (PTFE), peek, urethane, or ethylene propylene (EP).

The suction head 3 may be connected to the cassette in an airtight manner and/or gastight manner, thereby guaranteeing the high purity of the recovered gaseous C0₂. This makes the subsequent reliquefaction possible. This is very advantageous as it minimizes the costs.

In a preferred embodiment, a similar airtight and/or gastight manner connection can be provided for the snowgun (2) and the cassette (5).

In a preferred embodiment, the connection of the suction head and the loading pistol to the cassette is ensured by electromagnetic force. In a preferred embodiment, reliquefaction of the recovered gaseous C0₂ comprises the steps of compressing said gas to reach about 18 to 20 barg and reintroduce the compressed C0₂ into the liquid C0₂ storage tank.

In a preferred embodiment, in operation mode, the suction head is first activated so as to create a vaccum effect in the cassette. After activation of the suction head, the loading pistol will be activated for the injection of cooling medium. This allows minimizing the impact on the cassette, placed in the container, of the cooling medium injection. This in turn ensures a better security. In fig. 1, the suction head 3 is connected to the ventilator 7, which removes the gaseous C0₂ produced during decompression of liquid C0₂. The usage of ventilator is a necessary prerequisite for making the process safer, however it is one of the aspects of the invention to use the heat absorbing capacity of the cold gas within the distribution centre. In the non-limiting example presented in fig. 1, this goal is realized within the heat exchanger 8, which uses the cold gas, having temperature comprised between -50°C and -70°C to cool down the liquid C0₂.

The hoses 9 and 10 that are used for transport of liquid and gaseous C0₂ should preferably be insulated. In case of the liquid C0₂ hoses, the hoses should preferably be insulated with vacuum insulation. Insulation protects the workers from contact with cold surfaces, eliminates condensation of water vapour on hoses and decreases the heat losses of liquid C0₂. In a preferred embodiment, on the hose 9, which transports liquid C0₂ to the snowgun, there is a phase separator 11, which removes the gaseous C0₂ created during the idle time within C0₂ hoses. This solution enables the user to start injecting liquid C0₂ into the cassette right away, without waiting for the gas to be removed from the lines.

The phase separator 11 is schematically shown on fig. 5. There is a floating element 112 in the separator casing 111. If there is no or little gaseous C0₂ in the liquid line, the floating element 112 rises and, with the help of spring 113, closes the cut-off valve 114. If there is, however, a significant amount of gas in the liquid line, the gas collects within casing 111, lowering the floating element 112, thereby opening the cutoff valve 114 and letting gaseous C0₂ out.

In order to make connection to C0₂ source and to exhaust system, at the rear of the control cabinet there is a connection 12 for liquid C0₂ and a connection 13 for the exhaust hose for gaseous C0₂. Any type of connection apparent to a person of professional skill can be used, providing that it guarantees adequate flow of both fluids and operator safety. For liquid C0₂, a good trade-off between the need to simplify the operation and the need to guarantee appropriate safety performance are quick coupling connections. For gaseous C0₂ a much wider choice can be made by a person skilled in ventilation.

The control cabinet is equipped with wheels 14, making it mobile. The wheels are equipped with mechanical brakes (not shown on the figures) which have to be used during loading process. It is also advantageous to use the brakes while the control cabinet is unused in order to prevent any movement.

On fig. 2 another embodiment of the invention is shown, wherein the control cabinet 1 and external exhaust ventilator 15 are placed on a frame 16. The liquid and gaseous C0₂ hoses (9 and 10) are led from the control cabinet 1 to the trolley 17 along the upper part of the frame 16 and then vertically to the snowgun 2 and the suction head 3. This solution facilitates the horizontal movement of the snowgun 2 and the suction head 3 and adjusting the position of the snowgun 2 and the suction head 3 to the position of the isothermal container 4.

The snowgun 2 and the suction head 3 are additionally equipped with a system of counterbalances 18. This reduces the amount of work required to operate the equipment. The control box 6, shown in detail on fig. 2, and schematically on fig.l, fig. 4, fig. 9, is equipped with a programming device 61 which allows for choosing the time of the injection, depending on the (i) weather conditions, (ii) the necessary temperature within the container, (iii) the length of the road, (iv) the time of storage after transport and (v) the type of transported goods. In the control box 6 there is also the access control system, which protects the employees from unintended startup of the system. The system can be operated on several principles, e. g. mechanical key, numeric access code, electronic chip, or any similar system apparent to person of a professional skill.

The control box 6 is also equipped with electronic safeguards for safety of the operators, which consist, for example, of:

- Safety switch disabling the liquid injection in case the snowgun is disconnected

- Safety switch disabling the liquid injection in case the suction head is disconnected - Safety switch disabling the liquid injection in case the ventilator does not run

- Safety switch disabling the liquid injection in case the ambient C0₂ concentration is above thresholds

The control box 6 may be a part of the control cabinet 1, as in fig. 1 or it can be mounted separately, as in fig. 2.

In fig. 3 another non-limiting embodiment of the control cabinet 1 is shown. In this particular embodiment the liquid C0₂ piping 9 is constructed in such a manner that three independent snowguns 2 can be connected with the help of manifold 19. Such system is advantageous, as it allows loading three containers 4 to be loaded within the same time with different amounts of snow. The gaseous C0₂ lines 10 are also constructed in such a manner allowing for simultaneous usage of three suction heads 3 with the help of manifold 20. The control system of this embodiment is not shown for clarity. Any system obvious to a system skilled in the art can be used. It is self- evident that the number of independent snowguns and independent suctions heads are to be adjusted to the need of the user.

Fig. 4 presents another non-limiting example of the system. This one is thought as a solution to users who fill lots of containers with identical amounts of snow. In such case it is advantageous from the organisational point of view to inject liquid C0₂ into several cassettes 5 at once. In order to do this, the snowgun 2 is replaced with an injection manifold 191, and the suction head 3 is replaced with suction manifold 201. This arrangement allows for a simultaneous connection of several containers at once, thereby shortening the loading time of a container.

Fig. 8 presents a non-limiting example of a filling process of the cassette 5 wherein the liquid C0₂ is being supplied by the snowgun 2, while the gaseous C0₂ is being withdrawn with the suction head 3. In this particular embodiment the process is being facilitated by temporary connection of the snowgun 2 and the suction head 3, which ensures the proper adjustment of the snowgun 2 and the suction head 3 in the cassette 5.

Fig. 9 is a non-limiting example of another embodiment of the invention, where the heat absorbing capacity of gaseous C0₂ produced during decompression is being used for cooling of the inlet fresh air. In that particular non-limiting example the cold gaseous C0₂ from decompression is pumped by ventilator through an opening in the external wall SZ to the heat exchanger 8. The fresh air which allows for efficient ventilation of the room is being sucked through the heat exchanger 8 (the room ventilation system is not shown).

The ventilator 7 doesn't have to be placed within the control cabinet 1 but instead the suction head 3 and the transport lines 10 of the gaseous C0₂ can be connected to a large main ventilator (not shown). In this way the weight of the control cabinet may be lessened, but more energy consumption from the main ventilator may result. The decision depends on local conditions and user choice. A system with one main ventilator is presented as a non-limiting example in fig 10 (some elements from previous figures have been omitted for clarity).

In fig. 10 a schematic of the whole distribution centre CD is presented together with the C0₂ removal lines 101. The distribution centre CD has one frozen storage room MR and one chilled storage room CH. In fig. 10, three control cabinets 1 are connected through the gas connection 101, while two connections 102 to the system of removal of gaseous C0₂ are left idle.

In fig. 10 another non-limiting example of recuperation of heat absorbing capacity of gaseous C0₂ is shown. The cold gas is being passed through a heat exchanger 8 placed in the frozen storage room MR, thereby decreasing the air temperature and saving user's expenses on air cooling.

It is self-evident and obvious to the person skilled in the art that the dimensions of the filling station of the invention are to be adapted to the requirements of the user. These dimensions comprise length of the different hoses, height of the control cabinet, height and width of the frame.

In a preferred embodiment, the cassette is filled while being placed in the isothermal container. Regarding the of functioning of the system, the invention is characterized in that before the injection process the snowgun and the suction head can be connected to cassette one after another as separate entities and after the injection process the snowgun and the suction head are disconnected from the cassette as separate entities while during the injection process the gaseous C0₂ is removed with a ventilator and used, after decompression, for cooling.

The system of the present invention provides for additional organisational flexibility in the distribution centres by using mobile loading station. It also allows additional organisational flexibility in the distribution centres by using exchangeable heads for liquid injection and gas suction and control cabinets with multiple liquid filling and gas removal lines. Hence, the work efficiency is increased by making simultaneous filling of several containers possible. The safety is also increased by giving access to control station only to authorized users. Loading pistol

Fig. 11 illustrates a particular embodiment of the pistol according to the invention, in which the pistol has been constructed for a cassette 306 which enables usage of two temperature ranges in the container.

In this non-limiting example liquid carbon dioxide is fed into the pistol through a single pipe 313. The pipe branches into pipes 323 and 333 which are dedicated to different filling holes 302 and 303. In a preferred embodiment, through the hole 302 liquid carbon dioxide is fed into cassette compartment for keeping the temperature in the range of -10 to 10°C, preferably -5 to 5 °C, more preferably 0 to 4°C, while through the hole 303 the liquid carbon dioxide is being fed into cassette compartment for keeping the temperature in the range of -25 to 0°C, preferably -20 to -10°C, more preferably around -18°C.

In a preferred embodiment, the pipes 323 and 333 are mounted with on-off valves 322 and 332, which allow for control of the supply of the liquid C0₂. Further from the valves, the pipes 321 and 331 are brought together to form the loading pistol outlet 312.

It is to be understood, that depending on the user's needs, there may be more supply tubes for liquid C0₂ in the pistol outlet and the cassette may have several compartments for the respective additional temperature ranges.

It is to be understood, that the above example is a non limiting one, and, for example, the carbon dioxide used for filling cassette can be simultaneously fed through both holes 302 and 303 and the tubing can be constructed in another way.

In a preferred embodiment, the choice of the cassette zone to be filled can be automated. On fig. 11 a control element RF is illustrated, which can be for example, an RFID chip, which is a programmed sender 315. In a further preferred embodiment, the transmitter of the RFID chip is located in the container and/or in the cassette while the receiver of the RFID chip is located in the loading pistol. The element RF controls the valves 322 and 332 in a way enabling supply of proper amount of C0₂ to the appropriate chambers of the cassette 306. The amount of C0₂ depends on the (i) weather conditions, (ii) the necessary temperature within the container, (iii) the length of the road, (iv) the time of storage after transport and (v) the type of transported goods.

Fig 12 illustrates in detail an exemplary embodiment of the pistol of the invention. The loading pistol outlet 312 is shown with greater detail there, showing the position of the loading holes 302 and 303 respective to the outlet 312. As can be seen on the figure, the holes are not coaxial with the loading pistol outlet 312, but instead open on the side of it. Hence, the direction of the injection of liquid C0₂ is substantially perpendicular to the outlet (312) of the loading pistol (301). Thanks to that, the return force created through decompression of liquid carbon dioxide leaving the holes 302 and 303 is not directed along the loading pistol outlet 312, and does not push the outlet 312 and the pistol out of the cassette.

Fig. 13 illustrates the two compartments 304 and 305 of the cassette 306 together with the opening for gas evacuation 307. Filling of the compartment 304 allows for keeping temperature in the range 0-4°C, while filling of the compartment 305 allows for keeping temperature around -18°C. As can be seen from the picture, the outlet 312 is constructed in such a way, that the filling hole 302 opens into the compartment 304, and the filling hole 303 opens into compartment 305. The above example is a non-limiting one, and other setup of the compartments in the cassette is possible. The difference of temperature maintained in the chambers of the cassette compartments 304 and 305 lies in their heat transfer properties. This difference can be obtained changing these properties.

In a preferred embodiment, said difference is obtained by changing the thickness of the planes defining the cassette; preferably changing the thickness of the cover of the cassette. The thickness of the cassette's cover is comprised between 0.5 and 10 mm, preferably between 1 and 9 mm, more preferably between 1.5 and 8 mm, most preferably between 2 and 7 mm, even most preferably between 4 and 5 mm. In another preferred embodiment, said difference is obtained by changing the material of the planes defining the cassette; preferably changing the material of the cassette's cover. The cassette cover can be made out of plastic, ferro and non-ferro metals.

In another preferred embodiment, said difference is obtained by changing the heat exchange area of the planes defining the cassette; preferably changing the heat exchange area of the cassette's cover. Said heat exchange area is comprised between 5 and 100%, preferably between 10 and 90 %, more preferably between 20 and 80%, most preferably between 30 and 70% of the cassette cover. In another preferred embodiment, said difference is obtained by changing the gas flow around the cassette.

These solutions are given here as an example. Other solutions will be obvious to the person skilled in the art.

In a preferred embodiment, the gas created during decompression of liquid C0₂ in the compartment 305 can be transferred to the gas outlet 307 without impairing the basic characteristics of the cassette 306. Fig. 14 illustrates the basic mode of operation of the cassette. The solid carbon dioxide deposited in the cassette 306 cools down the gas contained within the upper part 309 of the container. The cold gas flows down along the walls of the container and contacts the goods 311 within the container. In order to facilitate the gas flow, the inner part of the container can be equipped with grooves 310, here shown only on the floor. As the gas warms from the walls and the goods, it flows into the upper part 309 of the container, where it is cooled down again. In fig. 14 an example of the electronic sender 315 position is also shown.

Fig. 15 illustrates one of the particular embodiments of means of increasing the heat transfer through the top of the cassette 306. In that particular embodiment the top of the drawer 361 is grooved, thereby increasing the heat exchange area and intensifying the turbulence of the gas movement around it.

On fig. 15 the front spacer 362 and the rear spacer 363 of the cassette 306 are shown. The spacers are shown in more detail on fig. 16 and fig. 17. On fig. 16 there are examples of spacers 362 and 363 which are mounted in the front and in the back of the cassette 306. On fig. 17 there are examples of spacers 365 which are mounted at the sides of the cassette 306. The spacers 362, 363 and 365 are exchangeable parts that can be mounted on a cassette. The shape of the spacers conforms to upper part 309 of the isothermal container. Thanks to that, the cassette can be mounted on any container and there is no need to design and produce additional sorts of cassettes for different types of containers.

An example of the connection 364 between the gas outlet 307 and the inlet for loading pistol 308 is presented on fig. 15 and fig. 16. The connection can be, for example, an electrical cord, which would signal, if both the loading pistol 301 and the suction head 314 are properly mounted. The connection would also signal if either the loading pistol 301 or the suction head 314 is connected to the cassette. In such a way the safety of the operator is increased, as the system will not start, if it's not properly mounted in a safe way.

On fig. 18 a schematic embodiment of connection of the snowgun with cassette 306 is presented. In this example the cassette 306 is equipped with magnet 351, in which a ring 352 is grooved. An identical magnet 353 is mounted on the snowgun and in its grove an O-ring gasket 354 is placed. The strength of such connection is provided by the magnets 351 and 353, while the gasket 354 is meant to provide tightness. Cassette

Fig. 19 illustrates a schematic exemplary embodiment of the cassette 406 placed in the container 409. The loading pistol 401 and the suction head 414 are also shown. For clarity, the fixing rope and some piping of the loading pistol 401 and the suction head 414 are also shown. Fig. 19 illustrates also an exemplary placement of the inlet hole for liquid C0₂ 408, of the gas removal hole 407 and of the metal plates 455 and 456.

Fig. 20 illustrates one of the features of the invention. There, at a view from above, the preferred placement of the gas collection chamber 451 in the cassette 406 is shown, relative to the cooling chambers 404 and 405. Fig. 21 illustrates the placement of the separation plane 457. The plane covers the cooling chambers 404 and 405, but does not cover the gas collection chamber 451. The separation plane 457 consists of two metal grids 458, of which only the upper grid is shown in fig. 21, and of the separation fabric 459. The separation fabric can be made of any material resistant to low temperatures which is able to act like a sieve for solid C0₂. During the expansion process, the gaseous C0₂ is evacuated through the separation plane 457 into the gas collection chamber 451 and further to the gas withdrawal hole 407. The solid C0₂, which is meant to stay in the cooling chambers 404 and 405 is retained on the separation fabric 459. The separation fabric may be made out of polyethylene, preferably woven polyethylene. The grids can be made out of metal or any other material suitable to withstand low temperatures, such as a composite.

The two grids 458 are holding the separation fabric 459 in place. The two grids are used in order to increase ruggedness of the cassette 406 and to eliminate the need to maintenance, which may appear, should the separation fabric 459 move and open a way for solid C0₂ to move from one of the cooling chambers 404 or 405.

In fig. 21 metal plates 455 and 456 are also presented, with their placement in the cassette 406. The plates fulfil two goals at once. First, they are the elements to which the loading pistol and the suction head, respectively, are magnetically attached during the C0₂ injection process. Second, thanks to the presence of the metal plates 455 and 456, the system controls, at the beginning of the loading process, whether the loading pistol and the suction head are present and properly connected. Fig.22 illustrates the placement of the gas guiding lines and of the separation rib 453. The guiding lines are placed above the separation plane 457. The gas guiding lines are created by providing corrugated channels 452 in the cassette lid . The gaseous C0₂ from decompression, which is leaving the cooling chambers 404 and 405 through the separation plane 457 enters the guiding lines and is being transferred into the gas collection chamber 451. From the gas collection chamber 451 the gas is evacuated through the gas withdrawal hole 407. The corrugated channels 452 are preferably longitudinal, parallel to each other and cover at least 50%, preferably 70%, more preferably 80%, most preferably 100% of the cassette length. The number of corrugated channels 452 is comprised between 1 and 25, preferably between 2 and 20, more preferably between 3 and 15, most preferably between 4 and 10. The corrugated channels 452, in cross sectional view, can be of any shape such as circular, rectangular, triangular, conical, inverted conical, inverted frusto-conical or frusto-conical shape as presented in fig. 22.

The height (H) of the corrugated channels 452 from the upper metal grid, as presented in fig. 22 a, is comprised between 0.5 and 15 cm, preferably between 0.8 and 13 cm, more preferably between 1 and 10 cm, most preferably between 1.2 and 8 cm, even most preferably between 1.4 and 6 cm. The width Wl of the lower side of the frusto conical shaped corrugated channels is comprised between 0.5 and 8 cm, preferably between 0.6 and 6 cm, more preferably between 0.8 and 5 cm, most preferably between 1 and 4 cm. The width W2 of the upper side of the frusto-conical shaped corrugated channels is comprised between 1 and 6 cm, preferably between 1.2 and 5 cm, more preferably between 1.4 and 4.5 cm, most preferably between 1.6 and 4 cm. The angle β, shown on fig. 22 a is comprised between 10 and 170°, preferably between 30 and 160°, more preferably between 50 and 150°, most preferably between 70 and 140°, even most preferably between 90 and 130°.

The presence of corrugated channels 452, their shape and size provides a freedom and a possibility to optimize the injection speed and/or the volume of gaseous C0₂ that can be created during said injection. The separation rib 453 is created by a deepened groove in the lid 461. Such design allows for achieving separation of cooling chambers 404 and 405 from each other without additional elements. The separation rib 453 is pressing the separation plane 457, additionally increasing the mechanical stability of the separation plane 457. It also presses the separation plane 457 to the chamber separation element 454, thereby preventing any transfer of solid C0₂ from one chamber to another.

In a preferred embodiment, the separation element (454) is provided with a construction suitable to direct a simultaneous, separate or subsequent injection of liquid C0₂ in the cooling chambers (404, 405) of the cassette (406). In a preferred embodiment, the separation element has a construction allowing for the introduction of the loading pistol (401) outlet. The separation element might comprise a tunnel through which the pistol is introduced.

In a preferred embodiment, the loading pistol is, as detailed above, provided with an outlet (312) containing separate piping (323, 333) and outlet holes (302, 303) for deposition of solid C0₂ in the cooling chambers. The separation element 454 is provided with at least two openings for fluid connection between the cooling chambers (404, 405) and the loading pistol (401). It will be obvious to the person skilled in the art that the openings are positioned on sides of the separation element such as to ensure said fluid connection. It will be also obvious that the outlet holes (302, 303) of the pistol should correspond with the opening of the separation element for a successful introduction of the cooling medium.

In a preferred embodiment, the openings of the separation element can be of any shape; circular, oval, preferably rectangular. In a preferred embodiment, to ensure that the cooling medium will be injected in the cooling chambers of the cassette, the size of the openings of the separation element is at least twice the size of the outlet holes (302, 303) of the pistol. In a further preferred embodiment, the longitudinal size of the openings of the separation element is at least twice the size of the outlet holes (302, 303) of the pistol. For example, the case wherein the openings of the separation element have a rectangular shape and the outlet holes are circles of 1 cm diameter. In this case the length of the rectangular opening will be at least 2 cm, while the width will be at least 1 cm. It is to be understood that the opening width should not allow solid C0₂ to leave the chambers under any circumstance.

In a preferred embodiment, the separation element is made of metal.

In another preferred embodiment, the separation element is made out of plastic that can withstand very low temperatures, preferably lower than -80°C.

In an embodiment of the invention, magnet elements could be positioned at and/or around the openings of the separation element and at and/or around the outlet holes (302, 303) of the pistol. This will ensure the correspondence of the openings and the outlet holes. Here, it is obvious that the material of the pistol outlet and the separation element itself should be selected as to resist the injection pressure and the temperature of the cooling medium but also as to not react to the presence of the magnets at the openings of the separation element and at the pistol the outlet holes (302, 303).

The separation element can be designed to pass through, under or at the side of the gas collection chamber 451 of the cassette.

In fig. 23 the lower part of additional heat exchange element 512 and the upper part of additional heat exchange element 511 are shown in a cross view from side. The two parts 511 and 512 are fixed together and together they are attached to the cassette 406, which increases the ruggedness of the cassette 406 and broadens the ranges of temperatures which can be maintained in the container. The cassette of the present invention is a closed and gastight cassette. More in particular, the lid of the cassette is gastight. The cassette ensures mechanical ruggedness and facilitates gas removal, without being a large and massive cassette.

In another aspect, the present invention provides a method for maintaining low temperature in an isothermal container comprising at least one cassette with at least two cooling chambers able to maintain different temperature ranges in the container, whereby the chambers are simultaneous, separate or subsequently filled with a predetermined amount of liquid C0₂ through one aperture in the cassette. In a preferred embodiment, the method of the present invention comprises the steps of providing a cassette, a loading pistol and a filling station according to the present invention; connecting the suction head to the cassette; connecting the loading pistol to the cassette; providing a determined quantity of liquid C0₂ to the cassette using the loading pistol; removing gaseous C0₂ from the cassette using a suction head, the snowgun and the suction head are connectable to the cassette by means of magnetic force. In a preferred embodiment of the method of the present invention, the snowgun and the suction head are connectable to the cassette by means of electromagnetic force.

In a preferred embodiment of the method, the loading pistol and the suction head are separate and independently operable entities with regard to the control cabinet. In another aspect, the present invention provides for the use of the system, devices and/or the method of the invention for keeping low temperatures in an isothermal container for goods transport, such as foodstuff. The system, devices and method of the invention present several advantages. The injection process is simplified due to the use of smaller and lighter equipment, additionally equipped with counterbalances. The use of one inlet hole in the cassette for liquid C0₂ injection for different temperature ranges to be attained simplifies the filling operation.

Higher work flexibility in distribution centres is provided thanks to usage of mobile control cabinets. The injection process is easier thanks to protection of the snowgun against freezing. The injection process is faster thanks to the phase separator mounted on liquid C0₂ line. The work efficiency is higher due to potential filling of several drawers at once. The equipment for C0₂ dosing and withdrawal is safer and more lasting thanks to its placing within a protective frame. Also there is an increase of the economic efficiency of the distribution centre thanks to usage of cold gaseous C0₂ produced during decompression of liquid C0₂ and an increase in the safety of the system due to the access restrictions for unauthorized users. Additionally, an improved organisation of the distribution centres is offered thanks to the use of separate, exchangeable elements for liquid carbon dioxide injection and gaseous C0₂ withdrawal and of control cabinets equipped with several lines for supply of liquid C0₂ and withdrawal of gaseous C0₂. The system, devices and method of the invention further provides the user with a choice for different magnetic strength between the cassette and the pistol and between the cassette and the suction head. Hence the connection strength can be optimized. The cassette construction allows improving the quality of transported goods by protecting them from over freezing. The cassette also provides a choice of temperature to be maintained in the container thanks to the presence and the construction of both chambers of the cassette. The injection process is automated by relying on automatics process for the choice of the cassette zone to be loaded and temperature range to be attained in the container. Further, the cassette spacers make it possible to combine the cassettes with different container types. The devices of the present invention can be used in combination with each other and/or separately in combination with other devices of the prior art and/or present on the market. The embodiments of the invention presented in the above examples are not limiting to the invention. Although the present invention has been described with reference to preferred embodiments thereof, many modifications and alternations may be made by a person having ordinary skill in the art without departing from the scope of this invention which is defined by the appended claims.

Claims

1. A cassette (406) for cooling products such as foodstuff in a container, suitable to contain a C0₂ cooling medium, such as liquid C0₂, whereby said cassette (406) comprising one inlet (408) for the introduction of the C0₂ cooling medium and one outlet (407) for the withdrawal of gaseous C0₂ formed while exposing the C0₂ cooling medium to atmospheric conditions, characterized in that, the inlet (408) and the outlet (407) are spatially separated and are both provided with magnetic coupling means.

2. The cassette according to claim 1, wherein the inlet (408) and the outlet (407) are cylindrical channels through a wall of the cassette (406).

3. The cassette (406) according to any of claims 1-2, wherein the lid (461) of the cassette is gastight.

4. The cassette according to any of claims 1-3, wherein longitudinal parallel corrugated channels (452) are provided in the lid (461) of the cassette.

5. The cassette according to any of claims 1-4, wherein the corrugated channels (452) have in cross sectional view a circular, rectangular, triangular, conical, inverted conical or inverted frusto-conical shape, preferably a frusto-conical shape.

6. The cassette according to any of claims 1-5, comprising two adjacent cooling chambers (404, 405) separated by a separation element (454) and at least one collection chamber (451) in front of said cooling chambers for collection of gaseous C0₂.

7. The cassette according to any of claims 1-6, wherein the separation element (454) is at least partly hollow and is connected at one end to the inlet (408) of the cassette.

8. The cassette according to claim 7, wherein the separation element (454) is provided with at least two openings, each opening is in fluid connection with each cooling chamber (404, 405) of the cassette (406).

9. The cassette according to any of claims 1-8, comprising a separation filter (457) covering the cooling chambers (404, 405) of the cassette (406) and positioned under the lid (461) of the cassette, said separation plane (457) is permeable to gaseous C0₂.

10. The cassette according to any of claims 1-9, wherein a predetermined quantity of liquid C0₂, sufficient to fill at least one cooling chamber (404, 405) is suitable to be injected in the cassette (406).

11. A filling station for the introduction of a C0₂ cooling medium such as liquid C0₂ and suitable to be used with a cassette as described in any of claims 1-10, said filling station comprising a control cabinet (1) provided with at least one loading pistol (2) for the injection of the C0₂ cooling medium in the cassette and at least one suction head (3) for the removal of gaseous C0₂ from the cassette, characterized in that, the loading pistol (2, 301) and the suction head (3) are separate and independently operable entities.

12. A loading pistol suitable for the introduction of a C0₂ cooling medium in a cassette as described in claims 1-10, characterized in that, said loading pistol (2, 301) is provided with an outlet (312) containing separate piping (323, 333) and outlet openings (302, 303), said loading pistol (2, 301) is suitable to be introduced, through the inlet, in the separation element of the cassette.

13. A system comprising a cassette as described in claims 1-10, a filling station as described in claim 11 and a loading pistol as described in claim 12 for cooling products such as foodstuff in a container.

14. A method for cooling products such as foodstuff in a container comprising the steps of connecting a loading pistol to a cassette for the introduction of a C0₂ cooling medium and connecting a suction head to said cassette for the withdrawal of gaseous C0₂ formed while exposing the C0₂ cooling medium to atmospheric conditions, whereby said suction head and said loading pistol are separately connected to the cassette and are magnetically connected to the cassette.

15. The method according to claim 14 wherein the withdrawal of gaseous C0₂ and the introduction of the C0₂ cooling medium are separately, simultaneously and/or subsequently performed.