FR2890863A1 - Continuous sterilising plant for products in multi-layer brick packages has steam heating and water cooling zones between input and output chambers - Google Patents

Abstract

The plant consists of an input chamber (3) followed by a zone (4) in which the products in brick packages are subjected to steam from injectors (13) at a pressure and temperature suitable for achieving sterilisation, a cooling zone (5) with compressed air inlets (17), in which the products are sprayed with water, and an output chamber (6). During the process the products are grouped in batches by supporting structures (9) on continuous conveyor systems (10). The two zones of the plant are separated by a partition (7) and connected by an aperture (8) in the partition at the opposite end of the chamber to the input and output chambers.

Description

The present invention relates to the sterilization of products

  packaged in flexible packages in the form of bricks made of multi-layer material based on cardboard. It relates more particularly to the facilities for performing the continuous sterilization of food type products.

  vegetables, soups, ready meals ... packaged in this type of packaging.

  In general, the food products are sterilized by applying high temperatures for a predetermined time.

  For this, systems operating either discontinuously (autoclave type) or continuously (see for example FR-1 492 032) are used, in which the products are subjected to water or water. water vapor at high temperature.

  In all cases, when the products to be sterilized are packaged in flexible packaging, their sterilization forces to maintain a permanent counterpressure during the heating and cooling phases, to prevent the packaging from bursting under the effect of the increase of their internal pressure, related to the increase of the temperature during treatment.

  An additional constraint appears in the case of products packaged in flexible packaging made of multilayer material based on cardboard (packaging type TETRA RECART registered trademark). Indeed, these cardboard packs are sensitive to water, and prolonged contact with water is likely to cause their degradation or deterioration.

  The known installations to date for the treatment of products packaged in such flexible paperboard packaging, consist of autoclave type structures using water vapor. However, these facilities are not entirely satisfactory because they provide sterilization by a discontinuous process. These autoclaves also have the disadvantage of not ensuring uniform sterilization of the packages, in particular according to the positioning of the package in the treatment chamber.

  To remedy these drawbacks, the Applicant has developed a new sterilization installation structure, particularly suitable for processing packaged products in flexible cardboard packaging. This facility has the advantage of allowing sterilization of products in a continuous process, and in a particularly homogeneous manner.

  For this, the sterilization installation according to the present invention consists of a pressure treatment chamber comprising, from upstream to downstream successively: a loading lock, a pressurized steam heating zone; , equipped with means allowing the application of pressure and temperature conditions adapted to ensure the sterilization of the products, - a cooling zone by spraying water on the packages containing said products, and - an unloading lock.

  This installation also comprises support structures for the grouping of a plurality of packages in batches, as well as means for the continuous transport of said support structures in said enclosure, from the loading chamber to the unloading station.

  According to a preferred embodiment, the installation comprises an elongated treatment chamber, with the loading and unloading locks located at one of its ends; the heating zone of this chamber is arranged above the cooling zone; on the other hand, the means of transport are adapted to convey the packaging support structures along the length of the enclosure, in accordance with several horizontal superimposed sections of the round-trip type, within each of the heating zones. and cooling.

  According to another feature, the heating and cooling zones are separated by a partition provided with an opening which is located at the end of the enclosure opposite to the loading and unloading lock.

  According to yet another characteristic, the heating zone is equipped with steam injection means associated with fan means, arranged at the end of the treatment chamber which is opposite to the loading and unloading chambers. The heating zone is also equipped, advantageously, with additional steam injection means, arranged at the end of the treatment chamber situated on the side of the loading and unloading chambers.

  Still according to another particularity, the installation comprises means for injecting compressed air into the cooling zone.

  Advantageously, the cooling zone is equipped with at least two water spray bars located, for one, in the upper part, above the different transport sections of the packaging support structures, and for the other, at an intermediate level, between two superimposed horizontal sections.

  According to another feature, the installation comprises packaging support structures of generally cylindrical shape, cooperating with transport means able - on the one hand, to convey said support structures with their longitudinal axis disposed horizontally, and - other on the other hand, to allow said support structures to rotate about their longitudinal axis in order to rotate the packages themselves, only at certain parts of the treatment chamber: in particular in certain parts of the heating and in some parts of the cooling zone.

  In this context, the transport means are advantageously shaped to cooperate with the packaging support structures in two positions: a so-called suspended position in which said transport means carry said support structures, the latter then not undergoing rotational movement and a so-called thrust position in which said structures rest on a fixed support plane and are rotationally rotated on said fixed plane by being driven by said transport means.

  According to yet another particularity, the means of transport comprise a return section arranged between the unloading chamber and the loading chamber, which return section passes through a return loop of the enclosure, which return loop comprises a water cap ensuring the sealing between the heating zone and the cooling zone of said enclosure.

  The invention will be further illustrated, without being limited in any way, by the following description of a particular embodiment, given by way of example only and shown in the appended single figure.

  As shown in this figure, the sterilization installation 1 has a structure particularly suitable for the continuous sterilization of products packaged in flexible packaging, shaped bricks, made of multi-layer material based on cardboard.

  The corresponding installation consists mainly of a pressurized sealed enclosure 2 of generally elongate cylindrical shape.

  This enclosure 2 comprises, from upstream to downstream (in accordance with the direction of travel of the packages detailed below), successively: a loading lock 3, a heating zone 4 by steam under pressure, within which the products are sterilized by high temperature, - a cooling zone 5 by water spray, in which the products previously mounted in temperature are cooled, and - an airlock 6.

  In the attached figure, it can be seen that the loading and unloading zones 3 are located at one of the ends of the sealed enclosure 2.

  It is also observed that the heating zone 4 is arranged above the cooling zone 5; they are separated by an intermediate partition 7, provided with a communication opening 8 which is located at the end of the chamber 2 opposite to the loading lock 3 / unloading 6.

  The products in brick packaging are grouped in batches in support structures 9, of generally cylindrical shape. These support structures 9 are conveyed, within the enclosure 2, by transport means 10 consisting of carrier chains.

  The support structures 9 are thus conveyed in a closed circuit, through the entire enclosure 2, at a given speed corresponding to the necessary sterilization time of the brick product.

  In this case, the transport chains 10 are arranged to convey the support structures 9 from the loading chamber 3, then successively in the heating zone 4, the passage opening 8, in the cooling zone 5, to the unloading lock 6. The path within each of the heating zones 4 and cooling 5 is performed here according to several superimposed horizontal sections 10 'of the return type; the heating zone 4 comprises in this case five transport sections 10 '(corresponding to two rounds and a half), and the cooling zone 5 comprises in turn three transport sections 10' (corresponding to a round trip and a half ).

  Outside the treatment zone 4, 5, a return loop 11 is arranged for the transit of a return section 10 "of the transport chains 10, between the unloading chamber 6 and the loading chamber 3. A water plug 12 is provided in a siphon zone located in this loop 11, to ensure sealing between the heating zone 4 and the cooling zone 5.

  In addition, in the present embodiment, the support structures 9 are conveyed by the transport chains 10 with their longitudinal axis disposed horizontally and with a possibility of being rotated around this longitudinal axis. As detailed below, the support structures 9 are advantageously rotated only on part of their path within the chamber 2 (in the heating zone 4 and in the cooling zone 5).

  The loading chamber 3 comprises a structure adapted for the transfer of the support structures 9, loaded in packages, from the atmosphere to the pressure vessel 2, where they are supported by the transport chains 10. This airlock loading 3 ensures the seal between the outside atmosphere and the heating zone 4 under pressure.

  Once inside the pressure vessel 2, the support structures 9 enter the heating zone 4 to sterilize the products. The ambient temperature and pressure conditions of this heating zone are obtained by steam injection means 13, arranged on the opposite side to the end of the chamber equipped with the loading chamber 3 / unloading 6. complementary steam injection 13 'are arranged at the end of the chamber 2 located on the side of the loading chamber 3 / unloading 6; this additional injection of steam makes it possible in particular to prevent the condensation of water on the cold packs which have just entered the enclosure 2 at the level of the loading chamber 3.

  Fan means 14 are associated with the steam injection means 13 to ensure homogeneity of the air and vapor mixture, in order to maintain a constant temperature in the heating zone 4.

  The support structures 9 then pass into the cooling zone 5, through the opening 8.

  The packaging is cooled by spraying fine water droplets on the support structures 9. The flow of water on the outer surfaces of the packages ensures the heat exchange necessary for cooling. Water is in this case projected by two sprayer ramps 15 and 16 disposed on the internal structure of the enclosure. More specifically, a first spray boom 15 is located in the upper part of the cooling zone 5, above the various transport sections 10 'of the support structures 9, and projects the cooling water to the underlying support structures 9; the second spray bar 16 is located at an intermediate level within the cooling zone 5, between two superimposed transport sections 10 '.

  In the cooling zone 5, there is advantageously still provided compressed air injection means 17, useful for adjusting the internal pressure of the chamber 2 to a desired value; this injection of compressed air into the cooling zone 5 optimizes the separation of the heating zones 4 and cooling 5 of the enclosure (in particular at the passage opening 8).

  At the outlet of the cooling zone 5, the support structures 9 are extracted from the chamber 2 by the airlock 6. This airlock 6 seals between the cooling zone 5 under pressure and the external atmosphere.

  The transport section 10 "empty passes through the return loop 11, to return to the lock 3 for a new loading support structures 9.

  As an indication, the pressure in the chamber 2 may be between 2 and 5 bar; the temperatures applied to the products in the heating zone 4 may be of the order of 100 C to 150 C.

  In general, the rotation of the packaging support structures 9 is carried out by any appropriate means.

  In this case, the transport means 10 are shaped to cooperate with the support structures 9 in two positions: - a so-called suspended position in which the transport means 10 carry integrally said support structures 9, the latter not then undergoing any rotational movement, and a so-called thrust position in which said support structures 9 rest on a fixed support plane and are rotationally rotated on said fixed plane by being driven by said transport means 10.

  In operation, in the heating zone 4 and preferably only part of this zone, the support structures 9 are rotated to ensure a homogeneous heat treatment of the products. On the other hand, in the cooling zone 5 and preferably only on a part of this zone, the support structures 9 are rotated in particular in order to optimize heat exchanges with the water to reduce the cooling time, and also to prevent the accumulation of water on the package likely to penetrate the slices of the carton, thus ensuring the durability of the integrity of the package.

  For example, the thrust position can be implemented on one or some of the horizontal transport sections 10 'in the heating and cooling zones 4.

Claims (9)

- CLAIMS -   1.- Installation for continuous sterilization of products contained in flexible packaging, in the form of bricks made of multilayer material based on cardboard, which installation consists of a pressure treatment chamber (2) comprising, of upstream downstream, successively: - a loading chamber (3), - a heating zone (4) by steam under pressure, equipped with means allowing the application of pressure and temperature conditions adapted to ensure the sterilization of said products, - a cooling zone (5) by spraying water on said packages, and - an unloading chamber (6), which installation further comprises support structures (9) for the grouping in batches of a plurality of packaging, as well as means (10) for the continuous transport of said support structures (9) in said enclosure (2), from said loading lock (3) to said unloading station (6).   2.- Installation according to claim 1, characterized in that it comprises a treatment chamber (2), with the loading chamber (3) and unloading (6) located at one of its ends, the heating zone (4) of said treatment chamber (2) being arranged above the cooling zone (5), and in that the transport means (10) are adapted to convey the support structures of packaging (9) along the length of said enclosure (2), this according to several superimposed horizontal sections (10 '), allerretour type, within each of said heating zones (4) and cooling (5).   3.- Installation according to claim 2, characterized in that the heating zones (4) and cooling (5) are separated by a partition (7) provided with an opening (8) which is located at the level of the end of the enclosure (2) opposite the loading chamber (3) and unloading (6).   4.- Installation according to any one of claims 2 or 3, characterized in that the heating zone (4) is equipped with steam injection means (13) associated with fan means (14), arranged at the level the end of the treatment chamber (2) which is opposite the loading chamber (3) and the unloading chamber (6), complementary steam injection means (13 ') being optionally arranged at the level of the end of the treatment chamber (2) located on the side of said loading chamber (3) and unloading (6).   5.- Installation according to claim 4, characterized in that it comprises means for injecting compressed air (17) into the cooling zone (5).   6. Installation according to any one of claims 2 to 5, characterized in that the cooling zone (5) is equipped with at least two water spray bars (15, 16) located, for one (15), in the upper part, above the different transport sections (10 ') of the packaging support structures (9), and for the other (16), at an intermediate level, between two superposed horizontal sections ( 10 ').   7.- Installation according to any one of claims 1 to 6, characterized in that it comprises packaging support structures (9) of generally cylindrical shape, cooperating with transport means (10) capable of a on the other hand, to convey said support structures (9) with their longitudinal axis disposed horizontally, and - secondly, to allow the rotation of said support structures (9) during their conveying around their longitudinal axis to ensure a rotation on themselves in certain parts of the treatment chamber (2), and in particular in certain parts of the heating zone (4) and in certain parts of the cooling zone (5). .   8.- Installation according to claim 7, characterized in that the transport means (10) are shaped to cooperate with the packaging support structures (9) in two positions: - a so-called suspended position in which said means of transport (10) carry said support structures (9), the latter then not undergoing rotational movement, and - a so-called pushing position in which said support structures (9) rest on a fixed support plane and are rotated in rotation on said fixed support plane because of their driving by said transport means (10).   9.- Installation according to any one of claims 1 to 8, characterized in that the transport means comprise a return section (10 ") arranged between the unloading chamber (6) and the loading chamber (3), which return section (10 ") passes through a return loop (11) of the enclosure (2), through a water plug (12) sealing between the heating zone (4) and the cooling (5).