AU2012342292A1

AU2012342292A1 - Device for cooling bulk products

Info

Publication number: AU2012342292A1
Application number: AU2012342292A
Authority: AU
Inventors: Jo Algoet; Bruno Weiss
Original assignee: Air Liquide SA; LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Current assignee: LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority date: 2011-11-24
Filing date: 2012-11-13
Publication date: 2014-06-12
Anticipated expiration: 2032-11-13
Also published as: AU2012342292B2; ES2722208T3; NZ624923A; EP2783172B1; EP2783172A1; WO2013076401A1; FR2983286B1; FR2983286A1

Abstract

The invention relates to a device for cooling bulk products, such as a device comprising a drum rotatably mounted on the axis thereof, said drum containing perforations distributed on the cylindrical lateral wall thereof in whole or in part. Additionally, the device comprises a motor for driving said drum and a thermally insulated chamber of elongate form along the axis of said drum and enveloping said drum, and means (2) for cooling products, for example products for injecting a cryogenic fluid into said chamber. The invention is characterised by the implementation of the following measures: - the device additionally comprises at least one ramp (3) for projecting a liquid cryogen, an additional ramp located inside the chamber opposite a portion of the drum wall located in the area where products enter the drum, - this additional projection ramp is capable of directing the liquid cryogen to said portion of the drum wall and through this portion of the wall, via said perforations, to the products that enter the drum.

Description

WO 2013/076401 1 PCT/FR2012/052605 DEVICE FOR COOLING BULK PRODUCTS The present invention concerns the field of devices for cooling bulk food products, of the type comprising a drum mounted for axial rotation, a drum 5 comprising perforations distributed over all or part of the cylindrical lateral wall thereof, a drum enclosed in a thermally insulated chamber (in order to illustrate this type of perforated-drum device, reference can be made to the document FR-2 512 533). The literature illustrates various types of cooling (methods for adding 10 cold) of products contained in the drum, and the above document FR-2 512 533 illustrates one of these methods (refrigerated convection), but, according to another of the methods listed, the cooling of products contained in the drum is obtained by the spraying of a liquid cryogen from the outside towards the wall of the drum and through this wall, the spraying system normally consisting of 15 manifolds extending along a wall of the drum, in general in the bottom part of the chamber. It is known that the functioning of such equipment is characterised by the need to regularly eliminate the snow or ice that forms and considerably disturbs 20 the functioning of the equipment and the efficacy of the heat exchange because of the blockage of the orifices in the drum. For this purpose, conventionally, at regular and preferably programmed intervals, a fluid such as compressed air, gaseous nitrogen or gaseous C02 is blown from the outside in order to eliminate the deposits of snow or ice formed 25 on the orifices in the drum. The pressure of this unblocking (cleaning) is typically around 6 bar. This method then requires a specific system for bringing and managing an unblocking gas in order to use this gas under pressure: namely a buffer tank WO 2013/076401 2 PCT/FR2012/052605 and the use of a pressure different from that of the supply of cryogen necessary for the actual operation of cooling the products. Among the well known drawbacks of these "unblocking" operations, the fact can be mentioned that, in the case of compressed air, contamination 5 thereof may cause that of the food product being treated in the drum (by oil, moisture, etc.), without forgetting the fact that the use of a gaseous "unblocking" flow at ambient temperature is prejudicial to the thermal balance and therefore to the consumption of cryogen of the method (liquid nitrogen, liquid C02). 10 The present invention sets out to propose a novel configuration and a novel method of operating such drum freezers, improving the overall efficiency of the operation and in particular the problem of unblocking of the orifices in the drum. 15 As will be seen in greater detail hereinafter, this objective and other advantages are obtained by the implementation of the following measures: - at least one manifold for spraying a liquid cryogen is added to an existing item of equipment, an additional manifold preferentially situated in a low position, under the drum, so that the orifices of the manifold can direct liquid 20 cryogen from the outside towards the wall of the drum and through this wall, over a length of wall situated in the inlet area of the drum; - this manifold is therefore termed "additional" since it is added to the existing means of injecting a cryogen into the drum in order to effect the cooling of the actual products according to the existing techniques mentioned above; 25 - this positioning of the additional manifold makes it possible firstly to abruptly cool this inlet portion of the drum so that the corresponding wall is put in a "zero adhesion" condition. This concept of "zero adhesion" is known to cryogenic experts: it is thus ensured that the surface in question is brought to a sufficiently cold temperature (below a given limit temperature that will be WO 2013/076401 3 PCT/FR2012/052605 explained later), so that the frost that will form on this surface attaches less, and will then be easier to make fall, but also so that the products treated in the drum are less adherent on the inside of the drum. "Sufficiently cold temperature" means a cryogenic temperature typically 5 below -50'C, but more preferentially below -80'C, for example around -90' to 100 C. - as has just been seen, this positioning therefore makes it possible to abruptly cool this drum inlet portion in order to limit the phenomena of adhesion, but it also contributes, as soon as the products enter, to effecting a precooling 10 of these products, at least on the surface, which can be called a "crusting" of these products. This therefore participates firstly in limiting the adhesion to the walls of the drum but also to begin cooling thereof, which is obviously very positive in terms of thermal balance. And it will be understood better from a reading of the above how the 15 present invention sets out to preferentially position this (or these) additional manifold or manifolds opposite the inlet area of the drum: this is because the invention, and this is its merit, seeks an action intervening as soon as possible as soon as the products enter the drum, products which, in some cases, arrive with a significant moisture level, which it is necessary to counteract since next 20 the products continue their travel through the drum, they are blackballed inside, and cooled, and the phenomena of frost and adhesion further in the drum are in practice limited or non-existent. - likewise as indicated above, the preferred positioning of this additional manifold according to the invention is a low position, under the drum, even if 25 other positionings, such as a position above, may be envisaged, for the following reason: this low positioning takes into account the fact that the products, as soon as they enter, "fall" into the drum, and this is therefore one way, and here again it is the merit of the present invention, to be better in a position to act as quickly as possible on the falling path of the products as soon WO 2013/076401 4 PCT/FR2012/052605 as they enter. - by way of illustration, the length of this additional manifold measures a few tens of centimetres, for example around sixty centimetres, and is situated at a short distance from the drum, in parallel, preferentially at a few centimetres 5 from the wall, for example not more than 3 cm from the drum. As will be clear to a person skilled in the art, this distance between the manifold and the drum may vary depending on the sizing of the manifold (number of spray nozzles on the manifold, spacing thereof, orientation thereof in space, etc.) but also the pressure of the cryogen, etc., and in any event it 10 would be sought not to move the manifold too far away in order to assist the action thereof, and a few centimetres (for example less than 5 cm, for example 3 to 5 centimetres) is then a preferred distance according to the invention. In other words, as will be clear in the light of the above description: 15 - if the cooling means of the installation comprise manifolds for injecting a cryogen inside the drum through orifices in the wall, the invention ADDS a manifold (at least one manifold) at the inlet; - if the cooling means of the installation do not comprise such injection manifolds (but other types of means, nozzles or convective devices or the like, 20 then the invention implements a spray manifold at the inlet combining with said other means. The present invention then concerns a device for cooling bulk products, of the type comprising a drum mounted for axial rotation, a drum comprising 25 perforations distributed over all or part of its cylindrical lateral wall, the device also comprising a motor driving said drum as well as a thermally insulated chamber of elongate shape along the axis of said drum and enclosing it, means for cooling the products, for example for injecting a cryogenic fluid into said chamber, and from there into the drum), characterised by the implementation of WO 2013/076401 5 PCT/FR2012/052605 the following measures: - the device also comprises at least one manifold for spraying a liquid cryogen, an additional manifold situated inside the chamber, opposite an outer wall portion of the drum situated at the area where the products enter the drum, 5 - this additional spray manifold is able to direct liquid cryogen towards the portion of the wall of the drum and through this wall portion, via said perforations, towards the products admitted into the drum. The present invention also concerns a method for cooling bulk products 10 of the type where the products are poured inside a drum mounted for axial rotation, a drum comprising perforations distributed over all or part of its cylindrical lateral wall, a drum enclosed by a thermally insulated chamber of elongate shape along the axis of said drum, and where means for cooling the products are available, for example for injecting a cryogenic fluid into said 15 chamber, characterised by the implementation of the following measures: - in addition at least more than one manifold for spraying a liquid cryogen is available, an additional manifold situated inside the chamber, opposite a wall portion of the drum situated at the area where the products enter the drum, - this spray manifold is able to direct liquid cryogen towards said wall 20 portion of the drum and through this wall portion, via said perforations, towards the products admitted into the drum, and - liquid cryogen is sprayed (preferentially continuously) onto and through said wall portion, throughout all or some of the operation of cooling the products implemented by means of said cooling means. 25 According to one of the embodiments of the invention, apart from the spraying of cryogen carried out during all or part of the cooling operation itself, liquid cryogen is also sprayed before the startup of the cooling operation, i.e. before the admission of the products, in order to precool the drum (refrigeration WO 2013/076401 6 PCT/FR2012/052605 of the installation). Other features and advantages of the present invention will emerge more clearly from the following description given by way of illustration made in 5 relation to the accompanying drawings, for which: - figure 1 is a partial schematic view of a drum cooling device according to the prior art; - figure 2 is a partial schematic view of a drum cooling device according to the present invention; 10 - figure 3 is detail view of an embodiment of the system for bringing cryogen to the cooling manifold (2) and additional manifold (3) in figure 2. Figure 1 shows a device for cooling bulk products in a drum 1 mounted for axial rotation, a drum comprising perforations distributed over all or part of 15 its cylindrical lateral wall (the perforations or orifices are not shown on the drum in figure 1 for reasons of legibility), as well as means for cooling the products, consisting here of a manifold 2 for spraying (injecting) cryogenic fluid (here liquid nitrogen) towards the wall of the drum and through this wall towards the products to be cooled in the drum, this cooling manifold 2 being situated here, 20 as is the case conventionally, in a low position under the drum 1. In accordance with the invention, the action of at least one additional manifold is proposed, which can be clearly seen in figure 2 (additional manifold 3), supplied by the same source of liquid cryogen upstream, an additional 25 manifold that is situated as a branch of the pipe supplying the cooling manifold 2. As will be clear to a food cryogenic expert, the number of nozzles on this additional manifold can be determined by experience and/or by simulation study (the latter will in particular consider the flow rate of product and the entry WO 2013/076401 7 PCT/FR2012/052605 temperature thereof). The detailed view proposed in figure 3 gives a better view of a possible method for supplying cryogen to the cooling manifold (2) and additional 5 manifold (3) in figure 2, a method that of course represents only one of the many possibilities for implementing such supply, a method where the following can be recognised: - a valve 6 supplying the portion 9 directing the cryogen to the additional manifold 3 and the portion 8 directing the cryogen to the cooling manifold 2; 10 - a proportional valve 7 governing the supply of cryogen, and therefore the temperature of the actual method for cooling the products (via the manifold 2); - elements for managing the gas safety, and in particular a valve 5, pressure gauges 4, etc. 15 The invention applies particularly to the quick freezing of bulk products and in particular solid food products with relatively small dimensions, such as for example diced bacon, minced meat, slices of sausages, finely chopped meat (hot and cold), scrambled eggs, mushrooms whole, in strips, or in cubes, 20 peas, sliced carrots, French beans, potatoes cut in chips or in cubes, and red fruit, including in particular strawberries, blueberries, blackcurrants or redcurrants. However, it is known that such drum installations are used for cooling other types of product, in particular lines for recycling tyres, electric cables, etc. 25 The present invention will highly advantageously apply also to these non-food industries. An installation such as the one shown in figures 2 and 3 has been used to successfully cool plum halves. By virtue of the invention, the use of compressed air of food quality, a WO 2013/076401 8 PCT/FR2012/052605 possible source of contamination and which represents a high cost, has been able to be eliminated on the production site in question. It has also been possible to show that the invention prevents the blocking (sticking) of the product at the entry to the drum: it is generally at this point that 5 the products remain, according to the prior art, clogged because of their relatively high temperature, and the use of the invention makes it possible to achieve, as was desired, a so-called zero-adhesion temperature on the internal surface of the drum.

Claims

1. Device for cooling bulk products, of the type comprising a drum (1) mounted for axial rotation, a drum comprising perforations distributed over 5 all or part of its cylindrical lateral wall, the device also comprising a motor driving said drum as well as a thermally insulated chamber of elongate shape along the axis of said drum and enclosing it, as well as means (2) for cooling the products, for example consisting of one or more manifolds for injecting a cryogenic fluid into the drum through said perforations, 10 characterised by the implementation of the following measures: - the device also comprises at least one manifold (3) for spraying a liquid cryogen, said spray manifold being situated inside the chamber, opposite a portion of the wall of the drum situated level with the area where the products enter the drum, 15 - this spray manifold is able to direct liquid cryogen to said wall portion of the drum and through said wall portion, via said perforations, towards the products admitted into the drum.

2. Cooling device according to claim 1, characterised in that said at least one spray manifold is positioned in the low position, under the drum. 20

3. Cooling device according to claim 1, characterised in that said at least one spray manifold is positioned in the high position, above the drum.

4. Cooling device according to one of the preceding claims, characterised in that said cooling means comprise a cooling manifold (2) situated inside the chamber, under the drum or above the drum, able to spray a 25 liquid cryogen towards the wall of the drum and through this wall towards the products, connected at its upstream part to a source of liquid cryogen through a proportional valve (7).

5. Cooling device according to claim 4, characterised in that said cooling manifold (2) is situated in a low position under the drum, and in that said WO 2013/076401 10 PCT/FR2012/052605 spray manifold (3) is also situated under the drum, and being also connected at its upstream part to the same source of liquid cryogen.

6. Cooling device according to claim 5, characterised in that said spray manifold (3) is situated at a distance from the wall of the drum not 5 exceeding 3 to 5 centimetres.

7. Method for cooling bulk products of the type where the products are poured inside a drum mounted for axial rotation, a drum comprising perforations distributed over all or part of its cylindrical lateral wall and which is enclosed by a thermally insulated chamber of elongate shape 10 along the axis of said drum, and where means (2) for cooling the products are available, for example consisting of one or more manifolds for injecting a cryogenic fluid into the drum through said perforations, characterised by the implementation of the following measures: - in addition at least one manifold (3) for spraying a liquid cryogen is 15 available, a spray manifold situated inside the chamber, opposite a wall portion of the drum situated at the area where the products enter the drum, - this spray manifold is able to direct liquid cryogen towards said wall portion of the drum and through this wall portion, via said perforations, towards the products admitted into the drum, and 20 - liquid cryogen is sprayed onto and through said wall portion, throughout all or some of the operation of cooling the products implemented by means of said cooling means.

8. Cooling method according to claim 7, characterised in that, in addition to the spraying of cryogen effected throughout all or part of the cooling 25 operation itself, liquid cryogen is also sprayed before the startup of the cooling operation, i.e. before the admission of the products into the drum, in order to pre-cool the drum.