WO2011048212A1

WO2011048212A1 - Device for production and distribution of co2 ice

Info

Publication number: WO2011048212A1
Application number: PCT/EP2010/065970
Authority: WO
Inventors: Gisle Espolin Johnson
Original assignee: Trosterud Mekaniske Verksted As
Priority date: 2009-10-22
Filing date: 2010-10-22
Publication date: 2011-04-28
Also published as: NO20093184A1; NO330749B1

Abstract

A device for filling of CO₂ into boxes and the like, where CO₂ snow is produced by releasing liquid CO₂ through one or more nozzles (5), wherein the device comprises a main chamber (3) in which the nozzle(s) (5) is (are) arranged over e feed screw (8), where the feed screw has a substantially horizontally arranged axis of rotation (9), and where the feed screw is arranged to, during rotation, transport CO₂ snow fro the area below the nozzle(s) (5) to an opening (12) for releasing CO₂ snow from the device, is described.

Description

DEVICE FOR PRODUCTION AND DISTRIBUTION OF C0₂ ICE The field of invention

The present invention relates to the field of generating of dry ice and, optionally, filling the produced dry ice into boxes or containers.

Background

Dry ice is under atmospheric pressure directly converted from solid state, dry ice or dry ice snow, to CO2 gas at a temperature of - 78 °C. Dry ice and CO2 snow may therefore be used for rapid cooling of materials and to keep the materials cold for a certain period. This may be used in the food sector, where food articles are to be cooled rapidly during production and be kept cold during transportation. For transport with no or too low cooling capacity, the use of dry ice may be the only option to keep the articles of food cold during transport. In its simplest from that is used for minced or ground meat products, CO2 gas is injected directly into the product during kneading of the minced or ground meat, causing a rapid cooling of the food product.

The mentioned method may not be used for food products that are not minced or ground, such as fish, in the form of whole fish, cleaned fish or cut fish or meat products in the form of whole pieces of meat. As an example is dry ice used for cooling of fish to be transported by air. The fish is then cooled by means of dry ice in an amount calculated to cool the fish sufficiently, so that all or most of the dry ice is sublimed before the transport actually takes place. Normally, dry ice in form of CO2 snow is used. The dry ice snow is produced by releasing liquid CO2 through one or more nozzles into a bell shaped dome. At atmospheric pressure the liquid CO2 is immediately converted to gaseous CO2 and dry ice snow, the dome reduces the of dry ice snow with the surrounding atmosphere. The gas phase escapes from the device, and the dry ice snow is collected below the dome and is distributed manually over the goods to be cooled. Boxes with food articles may, optionally, be transported under the domes as the dry ice snow is produced to get an automatic distribution of the ice snow on the goods. The known methods for production and distribution of dry ice snow, where the dry ice snow is distributed manually or is filled directly into boxes being transported under the domes for production of CO₂ snow, are not optimal and are unwanted of several reasons.

Generation of dry ice snow from liquid CO₂ generates great volumes of CO₂ gas. It is estimated that about 1 kg CO₂ gas is released for generation of 1 kg dry ice snow. This gas will displace the air in the production facilities and may make the facilities unsuitable to stay in for personnel unless the facility is thoroughly ventilated.

Accordingly, there is a need for a device for generation of CO2 snow was the problem of CO₂ gas inside the facility is avoided. Additionally, a manual process as described above is labour intensive, and there is a need for less labour intensive processes to reduce cost.

An additional problem is that the dosage of dry ice snow onto the goods will vary substantially by the above described methods, resulting an varying amount of dry ice snow and thereby uneven cooling of the product. The result may be that parts of the products freezes and other parts are not cooled sufficiently to obtain the requested quality on the products.

Three important requirements are to be fulfilled when filling CO₂ snow, or dry ice snow, onto products in a modern production facility for food articles:

• Large capacity for generation of CO₂ snow (amount per time unit),

• Exactness of the dosage of CO₂ snow, and

• Even distribution of CO₂ snow over the products. Accordingly, there is also a need for a device for generation of CO₂ snow that makes it possible to obtain an accurate and even distribution of the generated CO₂ snow over the products.

Summary of the invention According to a first embodiment of the there is provided device for filling of CO₂ into boxes and the like, where CO₂ snow is produced by releasing liquid CO₂ through one or more nozzles, wherein the device comprises a main chamber in which the nozzle(s) is (are) arranged over e feed screw, where the feed screw has a substantially horizontally arranged axis of rotation, and where the feed screw is arranged to, during rotation, transport CO₂ snow fro the area below the nozzle(s) to an opening for releasing CO₂ snow from the device. By means of the present device, a high capacity CO₂ is realized at the same time as the problem of releasing large volumes of CO₂ gas into the production facilities is reduced. At the same time a device for effective production and distribution of dry ice snow over goods, and preferably food products such as fish, reducing the need for manual work, is provided.

According to one embodiment, a ventilation pipe for venting CO₂ gas out of the device and preferably out of the production facility is arranged to the main chamber. By venting the amount of gasified CO₂ in the main chamber, the amount of CO₂ gas released into the production facility is substantially reduced. CO₂ released into the product will displace air and substantive ventilation will be needed to keep an acceptable working environment. Additionally, the ventilation pipe makes it possible to collect the CO₂ gas for recompression.

According to another embodiment, the opening is covered with a resistance plate (18) in the form of a net, a grid, perforated plate or the like. The resistance plate retardates the outgoing CO₂ snow and makes it possible to obtain a constant and better controlled delivery of CO₂ snow from the device.

Other embodiments are mentioned in the independent claims in the attached set of claims.. Short description of the figures

Figure 1 illustrates a longitudinal section of the present invention seen from the side,

Figure 2 illustrates a device according to the invention seen from one of the ends, Figure 3 is a bird's eye view of a device according to the present invention,

Figure 4 illustrates a resistance plate and knife, and

Figure 5 illustrates a detail of an embodiment of the present device. Detailed description of the invention

Figure 1 is a longitudinal section through the device 1 according to the present invention. The device 1 is arranged on a rack 2. The device comprises a main chamber 3, the lower half of which having a semicircular cross-section across the illustrated section, whereas the upper part has straight walls or funnel shaped walls, or a combination thereof as illustrated in figure 2.

One or more nozzle(s) 5 is (are) arranged on one or more nozzle tube(s) 5' in the upper part of the main chamber. One or more nozzles 5 may be arranged on each nozzle tube 5'. The nozzle(s) 5 / nozzle tube(s) 5' may be partly surrounded by bell shaped domes as described for the above mentioned solutions according to prior art. Tests do, however, indicate that the bell shaped domes are not necessary in the present device as the main chamber has the same effect as the domes, i.e. to avoid / reduce mixing of the CO2 snow and the surrounding air.

The nozzle tube(s) 5' is (are) connected to a CO2 manifold 6 via a CO2 tube 7. The manifold is connected to a not illustrated CO2 source and the purpose of the manifold is to distribute CO2 from the source to all nozzle tubes 5'. The manifold 6 is arranged above a cover 17 over the main chamber 3, whereas the nozzle tube(s) is (are) arranged below the cover 17, each having one or more openings or nozzles 5 directed downwards into the main chamber, so that CO2 snow produced in the upper part of the main chamber 3 falls down into the lower part of the main chamber 3 against a feed screw that is arranged onto and is rotated by an axle 9.

The nozzle(s) 5 and nozzle tube(s) may have any suitable design. The illustrated embodiment having straight, vertically arranged nozzle tubes each having a single nozzle at its lowermost end, is a presently preferred

embodiment. The axle 9 is driven by a motor 14, optionally via a gear box 15. When rotating the feed screw, the CO2 snow that is fallen down onto the feed screw from the nozzles is transported towards a tubular chamber 10 having a substantially circular cross section, which forms a continuation of the main chamber 4 and having a diameter that is substantially equal to the diameter of the lower semicircular part of the main chamber 3.

The feed screw 8 ends at a distance from a outlet 12 at the end of the tubular chamber 10 facing away from the main chamber. The outlet 12 is covered by a resistance plate 18. The resistance plate may be formed by bars, a grid, a perforated plate or the like.

A rotating knife 19 is provided at the outside of the resistance plate 18 relative to the main chamber 3. The rotating knife is preferably fastened to the axle 9 and is rotated together with the axle. The rotating knife 19 may alternatively be driven by other means. The rotating knife 19 comprises preferably two or more radial arranged knife blades. A bracket 1 1 may be arranged to the chamber 10 to support the axle 9 outside of the outlet 12.

During generation of CO2 snow liquid CO2 is provided to the nozzles 5 via the nozzle tubes 5' so that CO2 snow is formed outside the nozzles. The CO2 snow is falling to the bottom of the main chamber 3, and is transported towards the outlet 12 in the open end of the tubular chamber 10 by the rotation of the feed screw. The CO2 snow is retained by the resistance plate 18 at the end of the tubular chamber. The resistance in addition to the fact that the feed screw is stopped at a distance from the resistance plate 18 results in that the dry ice snow is retained by the resistance plate so that the dry ice snow fills the whole cross section of the tubular chamber at the end of the outlet, even if the level of dry ice in the main chamber do not exceed the top of the feed screw 8. Due to the fact that the total cross section of the tubular chamber is filled with dry ice snow at the free end, or end of the outlet, of the tubular chamber a predetermined dosage of dry ice snow that may be controlled by the rotation of the feed screw, is ascertained.

The device may also be provided with a cover outside of, and at the side of the opening 12 and the knife 19. This optional cover, where a downwards directed opening is provided between the outlet of the circular chamber and the cover, will protect the operator against the rotating knife and will also lead the CO2 snow downwards. The task of the rotating knife is do cut the CO2 snow coming out though the resistance plate 18 and assure that the snow is falling in a flow as uniformly as possible and in an optimally divided form onto the goods beneath the device. The number of blades on the rotating knife, at figure 4 illustrated with three blades, has to be adapted to the installation in question.

According to one embodiment the device neither comprises a resistance plate 18 or a rotating knife at the opening 12. This embodiment is especially suitable for production of CO2 snow that are to be manually distributed, but where the present device is preferred to get rid of the CO2 gas and avoid that the CO2 escapes into the production facility or at least reduce the amount of CO2 in the production facility.

According to one embodiment the pitch of the feed screw 8 is larger in the end closest to the resistance plate18 than beneath the nozzles in the main chamber 3, to ascertain an optimal control of the output of CO2 snow.

By controlling the amount of CO2 snow into the nozzle tubes and control of the feed screw rotation, the level of CO2 in the main chamber and the amount of dry ice delivered through the resistance plate, is regulated e.g. by means of a control unit 16 arranged at or near the unit as illustrated at figure 2.

Generation of dry ice from pressurized liquid CO2 results in emission of large amounts of CO2 gas that has to be withdrawn from the present device. To avoid or reduce emission of CO2 into the production facilities, a ventilation pipe 13 leading to the atmosphere is preferably arranged on the device.

The delivery of dry ice snow is preferably controlled by the control unit 16, receiving control signals from sensors 20. The timing for start and stop is preferably controlled by suitably arranged sensors 29, e.g. photo sensors.

Additionally weight cells for measuring the increasing weight of the boxes during filling may be arranged in connection with a conveyor arranged beneath opening 12 of the present device.

The generation of dry ice is suitably regulated according to the degree of filling of the main chamber. As mentioned above, it is practical that the degree of filling in the main chamber do not exceed the top of the feed screw 8, whereas the retardation of the transport speed due to the resistance given by the resistance plate 18, result in complete filling towards the free end of the tubular chamber 10. This may be controlled manually by experience and visual inspection, but of the frost formation on the equipment may result in reduced visibility and resulting inadequate control. Preferably, sensors are suitably arranged in the main chamber and in the tubular chamber, sensor that are connected to the control system 16. The control system 16 may, in addition to controlling the supply of dry ice to the device, control the rotation speed of the feed screw 8 and thereby the output speed of the device.

The present device and unit may for example be used for boxes filled with fish. The boxes with fish is transported on a not shown conveyor, such as a conveyor belt arranged between the legs of the rack 2 so that the boxes is transported in towards the free end of the tubular chamber 10 and enters between the legs of the rack. It is preferred that a conveyor that my be accurately controlled with regard to speed, is used., The delivery of CO2 starts when the front of a box has arrived at a predetermined position, delivering a constant flow of CO2 snow from the opening 12 by rotation of the feed screw to give the requested amount of dry ice per unit of time. The delivery of dry ice is again stopped by stopping the rotation of the feed screw as the as the rear end of the box passes a predetermined position. This is so repeated for the next box into which CO2 snow is to be delivered.

Figure 5 illustrates the output part of an alternative embodiment of the present device. In this device dry ice snow is produced in the same way as for the above described embodiment and the dry ice snow is delivered into the part illustrated in figure 5 by the feed screw 8 inside the tubular chamber 10. In this embodiment the feed screw ends inside the tubular chamber 10 and the axle 9 is supported by a bracket 21 . The knife is driven by its own motor 22, as operation of the knife 19 separate from rotation of the feed screw will give a better control over the production and delivery of dry ice snow.

A box 23 is arranged outside the opening 12 of the tubular chamber 10, including the resistance plate 18 and the knife 19, to avoid dry ice snow to escape in any other direction than directly downwards through an outlet 24.

A shutoff plate 25 is arranged to close and open the outlet 24, the shutoff plate being driven by a shutoff drive unit 26. The shutoff plate 25 improves the control with the release of CO2 snow from the device.

A collector 27 for CO2 snow, or dry ice snow, is arranged under the outlet 24. The collector 27 comprises a collector tray 28, having a horizontal area corresponding to the area of box filled with food articles to he covered with CO2 snow, arranged below the outlet to receive an predetermined amount of the CO2 snow. During delivery of CO2 snow to the collector plate, the shut of plate 25 is deactivated to open for the CO2 snow to fall onto the collector tray 28. To ascertain an even distribution of CO2 snow over the area of the collector tray 28, the collector tray 28 is moved back and forth for a predetermined time below the outlet 24, by means of hydraulic cylinders arranged in a collector base member 29 during the release of CO2 snow. The weight of the CO2 snow at the top of the collector tray 28 is then controlled by means of weight cells in the base member 29. The production of CO2 snow and/or the time for filling the required amount of CO2 snow onto the collector tray may be adjusted according to the registration of weight. Alternatively, or additionally, an alarm may be set to give an alarm if the weight is outside predetermined limits to allow the required actions to be taken.

When the collector tray is full, the tray is opened to allow the collected CO2 snow to fall into a box filled with food articles. In its presently preferred embodiment, the collector tray that is rectangular in shape, is divided in two halves longitudinally. Both halves are controlled by rotational actuators 30 that rotates each half about 90° from an horizontal position to a vertical position. It is important that the rotation is fast to ensure that the collected dry ice falls directly and evenly into the box filled with food articles.

It may be preferred to cover all internal surfaces in the present device with a suitable coating to reduce the sticking of CO2 snow onto the surfaces. Such a coating may reduce production stops due to the CO2 snow tendency to stick to surfaces and to itself as sticky snow. One example of a coating may be a coating of poly tetraflourethylene, e.g. as delivered under the trademark

Teflon®.

It may also be preferred to cover the present device with heat insulating material to reduce the ice formation on the outside of the device. The ice formation will in due course melt to form water droplets that may fall onto the goods unless adequate shielding is arranged above the goods.

Claims

P a t e n t c l a i m s 1 .

Device for filling of CO2 into boxes and the like, where CO2 snow is produced by releasing liquid CO2 through one or more nozzles (5), wherein the device comprises a main chamber (3) in which the nozzle(s) (5) is (are) arranged over e feed screw (8), where the feed screw has a substantially horizontally arranged axis of rotation (9), and where the feed screw is arranged to, during rotation, transport CO2 snow fro the area below the nozzle(s) (5) to an opening (12) for releasing CO2 snow from the device.

2

The device according to claim 1 , wherein a ventilation pipe (13) for CO2 gas is arranged to the main chamber (3).

3.

Device according to claim 1 or 2, wherein the opening (12) is covered by a resistance plate (18) in the form of a grid, net, perforated plate or the like.

4.

Device according to one or more of the preceding claims, wherein the feed screw (8) at the end close to the opening (12) is surrounded by a tubular chamber (10).

5.

Device according to one or more of the preceding claims, wherein a rotating knife (19) is arranged at the outside of the resistance plate (18) relative to the main chamber.

6.

Device according to one or more of the preceding claims, wherein the rotation of the feed screw (8) and the production of CO2 snow is controlled by a control unit (16).

7.

Device according to claim 6, wherein the speed of rotation of the feed screw (8) is controlled to control the output of CO₂ snow from the device.

8.

Device according to claim 6 or 7, wherein the supply of liquid CO₂ and thereby formation of CO2 snow is controlled as a response to the degree of filling of CO₂ snow in the main chamber (3).