FR2686964A1 - Apparatus for continuous cryogenic cooling of particulate products with pasty or solid character - Google Patents

Abstract

Treatment of particulate products by cold. The apparatus comprises: . at least one brush (5) having a helical arrangement (8) of bristles defining a cylindrical body centred on a shaft (6) linked to a rotational drive member (9-10), . a casing (1) surrounding the brush and defining at least one cylindrical half-containment complementary to the brush, . an inlet section (3) and an outlet section (4), for the product to be cooled, exhibited by the casing, . and means (11) for forcibly injecting into the said casing a cryogenic fluid subjected to pressure reduction (expansion) in the casing. Application to food products.

Description

APPARATUS FOR CONTINUOUS CRYOGENIC COOLING OF PRODUCTS
PARTICULARS WITH A PASTY OR SOLID NATURE
The present invention relates to techniques for solidification, cooling, freezing, deep-freezing or even sub-cooling of products by lowering their temperature by exchange with a sampling means, in order to give the products thus treated new characteristics. which can be maintained for relatively long periods depending on storage conditions.

 Among the preferred applications, the object of the invention relates, more specifically, to the food industry and relates, more particularly still, to the field of cooling, freezing and deep-freezing products to facilitate their packaging or storage, as well as to adapt their conservation condition.

 The treatment of particulate products with a view to ensuring their solidification, cooling, freezing or deep-freezing has hitherto been carried out either by means of mechanical refrigeration installations in which a refrigerant is subjected to variations phases by permanent recycling, either in cryogenic cold installations using lost cryogenic fluids.

 The actual cooling operation is carried out either in fluidized bed tunnels, or in immersion tunnels, or in rotary cylinders tilting with respect to the horizontal, or even in Archimedes screw systems.

 Installations of the above type experience a certain number of drawbacks, among which the following should be mentioned.

 Systems of the tunnel or cylinder type, whatever the cooling means used, do not allow good control of the advance of the product between the inlet and outlet sections. It has even sometimes been observed that 'in certain downward-sloping installations, changes in the supply and transfer conditions could generate the product going up against the slope.

 Such installations are known not to offer a regular advance of products which therefore do not undergo regular treatment When the products are not of a strictly homogeneous nature.

 By the way, in such installations, it is currently difficult, if not impossible, to evacuate the product being treated when the installation must be temporarily stopped for any reason.

Screw type treatment systems have
The disadvantage of causing either the jamming or the crushing of the product between the screw and the trough or the envelope which contains it.

For many applications, such an overwriting is unacceptable.

 Generally, such installations involve very long screws which, because of their rigidity, require high rotational drive powers.

 Furthermore, in one and / or the other of the systems described above, it is not possible to treat wet products on the surface and to which the form factor should be kept while avoiding solidification.

 The object of the invention is to remedy the above drawbacks by proposing a new cooling device with continuous operation, involving the technique of lost cryogenic fluid and capable of treating products of a particulate nature, that is to say that is to say either powdery or compact, or else preformed, preconditioned in grains, bars, plates, balls, balls, balls, etc., all bodies being able to present a pasty or solid character.

 The present invention also relates to a cooling device whose particular design makes it possible to give it a self-cleaning character whatever the product to be treated.

 Another feature of the subject of the invention is to be able to present particularly easy adjustment and adaptation methods as a function of the characteristics of the products to be treated.

 Another object of the invention is to offer great accessibility to all of the constituent bodies to facilitate maintenance, repair and inspection operations.

 Another object of the invention is to allow the easy production of an apparatus meeting the standards and requirements imposed for materials directly related to food products.

To achieve the above objectives, the object of
The invention is characterized in that it comprises
- at least one brush having an implantation
helical of flexible radial hairs and defining a
generally cylindrical body, centered on a
tree or longitudinal axis linked to an organ
rotational drive,
- a housing surrounding your brush and delimiting at least
a cylindrical half-envelope combined with the brush
and in which the latter is centered,
- an inlet section and an outlet section of the
product to be cooled presented by the housing,
- And means of forced injection into said housing
of a cryogenic fluid subjected to expansion in the
casing.

 Various other characteristics will emerge from the description given below with reference to the appended drawings which show, by way of nonlimiting examples, embodiments of the object of the invention.

 Fig 1 is a schematic sectional elevation of an apparatus according to the invention.

 Figs. 2 and 3 are sections taken respectively along lines II-II and III-III of fig 1.

 Fig. 4 is a cross section showing, on a larger scale, a detail of embodiment of one of the constituent elements of the device.

 Figs. 5 and 6 are two sections showing two alternative embodiments of the device.

 According to FIGS. 1 to 3, the continuous cryogenic cooling apparatus comprises a casing 1 forming a closed envelope having an inlet section 2 intended to be placed in relation to an apparatus 3 for continuously supplying products to be treated. The device 3 can be constituted by a conveyor belt or, for example, by a screw for drawing off a storage hopper, not shown.

By particulate products, it is advisable to consider all products not having, strictly speaking, a character
Liquid. It can therefore be powdered products, grain products or products in pasty mass or products having undergone a preliminary phase of partial agglomeration to be in a preconditioned particulate form, such as beads, dragees , balls, balls, wafers, dumplings, etc., this list having no limiting character. Likewise, the product to be treated can be considered to have a dry, pasty, more or less fluid or even partially wet character, having, for example, a liquid surface film, for example maintained by adsorption.

 The casing 1 comprises an outlet section 4 through which the treated product is discharged to an invisible station of recovery for all practical purposes. The inlet 2 and outlet 4 sections are preferably formed at the two opposite ends of the casing 1 which can be made of any suitable material.

 The housing 1 contains a movable body 5 of rotating nature comprising an axis or a shaft 6 which is mounted in bearings 7 of the housing 1. The rotating body 5 is constituted by a brush having a helical implantation 8 of bristles with radial direction, soft or flexible character. Preferably, the body 5 is constituted, as illustrated in FIGS. 2 and 3, by two brushes 51 and 52 whose shafts 61 and 62 are rotated in the same direction or in different directions and at equal or different speeds by at least one drive member 9 via a transmission system 10.

 In all cases, the casing 1 has a shape such that it internally defines an envelope conjugated at least for a half-part to the shape of the body 5 which represents, in the case of a brush, a continuous cylindrical body of diameter constant.

As a general rule, the casing 1 defines an envelope conjugated to the body 5, so that the hairs of the helical implantation 8 are compelled to rub against the peripheral wall of the envelope which develops around them by the presence of the casing 1, being subjected, moreover, to a certain elastic bending.

 FIG. 3 shows a particular example of conformation of the casing 1 offering by its internal envelope a form conjugated with the two juxtaposed cylindrical bodies, constituted by the brushes 51 and 52 which extend parallel to one another.

 For example, for the treatment of food products, the helical implantation 8 may consist of bristles, rods, segments, wires based on polyamide and of diameter substantially equal to 1 mm.

 The apparatus according to the invention is completed by means il of forced injection of a cryogenic fluid inside the casing 1. Such means 11 comprise, for example, at least one manifold ramp 12 having nozzles 13 s opening at least in line with the inlet section 2 and preferably also distributed over the useful length of the brushes 51 and 52 The cryogenic fluid used is preferably quiet carbon dioxide transported in a liquid manner '' at the injection point where it is transformed, by expansion by means of an appropriate nozzle, not shown in the drawings, into a gas phase and into a solid phase provided that the pressure at the outlet of the nozzle is equal or lower at 5 Bar absolute.

 The conditions of commissioning of the above device, for example for the freezing treatment of peas, consist in rotating the brushes 51 and 52 respectively in the direction of the arrows f1 and f2, so as to cause, at from the inlet section 2, on the one hand, a handling of the product supplied by the device 3 and, on the other hand, a routing of this product in the direction of the arrow f3 inside the housing 1.The product driven by the rotation of the brushes 51 and 52 is subjected to vigorous stirring in the presence of the cryogenic fluid which ensures, as a function of the speed of rotation and the helical pitch of the brushes 51 and 52, the cooling, the freezing , freezing or sub-cooling, so as to give it a compact and hardened character which it has at the outlet of section 4 where it is taken care of by any appropriate means with a view to ensuring its use or subsequent conditioning.

 The rotational speed of the helical brushes 51 and is adjustable between 3 and 300 revolutions / minute to ensure rapid movement of the product, so that the entire surface of the latter is brought into contact with the cryogenic fluid to avoid the appearance of stresses of surface that could be caused by too large temperature differences between various differently exposed areas.

 The passage time can be between 1 and 300 seconds and, more particularly, develops for 5 to 90 seconds, depending on the nature of the products, their form and the treatment which should be applied to them.

 By way of example, it can be considered that the brushes Si and 52 can have diameters ranging between 5 cm and 50 cm and that the helical pitch of the winding 8 of bristles taken at the periphery of the brushes can, for example, for example, being close to or equal, or of the order of magnitude of the diameter.

 In the same device, the two brushes 51 and 52 may have equal or different diameters and also have helical implantations of radial bristles having different helical pitches, oriented in the same directions or in opposite winding directions.

 As is apparent from the above, the product to be treated is introduced at one end of the casing 1 and recovered at the other, having undergone meanwhile, under the action of the cryogenic, mono or multiphase fluid, homogeneous cooling, account given the helical stirring that the said product undergoes by the rotation of the brushes 51 and 52 The presence of the helicoadal implantations, based on flexible bristles or the like, makes it possible to ensure minimal contact with the product and to achieve effective individual stirring of the particles, avoiding agglomeration of the particles present.

 The rotation of the brushes also makes it possible to avoid sticking of the particles of product against the walls of the casing. The product is thus preserved in its shape, which avoids any risk of denaturation of the particles.

 The presence of the flexible bristles makes it possible to promote the take-off and the expulsion of the products which could tend to attach or agglomerate on the casing, but also between the bristles constituting the brushes. In this way, a self-cleaning is maintained.

 It can be advantageous, as illustrated by FIG. 4, to conform the casing 1, at least locally, by a wall 15 comprising perforations 16 developing opposite a double wall 17 for recovery. Thus, in the case where the product to be treated has an adsorbed liquid film on the surface, the cooling, or even freezing of the latter, can produce granules of solidified liquid which are eliminated by the perforations 16 and by the spring effect exerted by flexible bristles.

 Fig 5 shows an alternative embodiment in which the device comprises a rotating body 5 which is constituted by a number of brushes greater than two. The brushes can rotate in the same direction or in opposite directions and have the same or different shapes and windings 8. In the case shown, the body 5 comprises four brushes 51 52 53 54 and the casing 1 is produced so that the envelope which it defines can be considered as generally combined with the shape of the body 5 formed by the four brushes arranged in parallel to each other.

 In such an embodiment, the four brushes can be positively rotated in the same direction or in the opposite direction and some of them can also be considered as passive, that is to say not positively rotated.

 In the foregoing, an example of setting up an apparatus in a horizontal arrangement has been shown, as illustrated in FIG. 2. It can be envisaged to make the device to give it a vertical arrangement, as illustrated in FIG 3. An intermediate orientation can also be adopted.

 The invention is not limited to the examples described and shown, since various modifications can be made thereto without departing from its scope.

Claims (9)

 1 - Apparatus for continuous cryogenic cooling of particulate products of pasty or solid character, characterized in that it comprises  - at least one brush (5) having an implantation  helical (8) of flexible radial hairs and  defining a generally cylindrical body  centered on a shaft or longitudinal axis (6) linked to  a rotary drive member (9-10),  - a housing (1) surrounding the brush and delimiting at  minus a cylindrical half-envelope combined with the  brush and in which the latter is centered,  - an inlet section (2) and an outlet section  (4) of the product to be cooled presented by the casing,  - And means (11) of forced injection into said  crankcase of a cryogenic fluid subjected to expansion in  the housing.  2 - Apparatus according to claim 1, characterized in that it comprises at least two brushes (5) extending parallel to one another in the same housing of which at least a half-envelope is conjugated to the shape of brushes.  3 - Apparatus according to claim 1 or 2, characterized in that the brushes have a helical pitch of the order of their diameter.  4 - Apparatus according to one of claims 1 to 3, characterized in that the brushes have different diameters.  5 - Apparatus according to one of claims 1 to 4, characterized in that the brushes have a helical implantation of bristles of different pitch.  6 - Apparatus according to one of claims 1 to 5, characterized in that the brushes have a helical implantation of bristles of different winding directions.  7 - Apparatus according to claim 1, characterized in that the means (11) for injecting the cryogenic fluid comprises at least one nozzle (13) near the inlet section of the housing.  8 - Apparatus according to claim 1 or 7, characterized in that the injection means (11) comprise a ramp (12) having injection nozzles (13) distributed over at least part of the length of the housing.  9 - Apparatus according to claim 1, characterized in that the housing defines at least one half-envelope (15) having at least locally perforations (16).