AIR DRYING PLANT AND METHOD FOR AIR DRYING CUT-UP FOOD

Abstract

The present invention relates to an air-drying plant for air drying cut-up food. The proposed plant consists of a conveyor (10) for cut-up food (1) defining a conveying surface (11), a plurality of blowing conduits (20) with blowing openings (21) channeling a treated airflow at a speed of treatment with a controlled temperature comprised between 4° C. and 60° C. and a controlled humidity; wherein the conveyor includes air treatment segments (12) with conveying surfaces (11) facing and adjacent to said blowing openings (21), said treated airflow being channeled against said conveying surface (11) in an upward or downward direction; and wherein the conveyor (10) also includes idle segments (13) intercalated between said air treatment segments (12), the conveying surface (11) of which is not facing the blowing openings (21), nor is it subjected to an airflow.

Claims

1. An air-drying plant for air drying cut-up food, including a conveyor (10) for cut-up food (1) defining a conveying surface (11) and a direction of conveyance a plurality of blowing conduits (20) including blowing openings (21) channeling a treated airflow with a temperature comprised between 4° C. and 60° C. and a controlled humidity; characterized in that: the conveyor includes air treatment segments (12) the conveying surfaces (11) of which are facing and adjacent to said blowing openings (21) of at least one of said plurality of blowing conduits (20), said treated airflow being directed against said conveying surface (11) of the air treatment segments (12) at a speed of treatment, directly affecting the cut-up food (1) in a downward direction or in a upward direction through the conveyor, the latter being perforated; the conveyor (10) also includes idle segments (13) intercalated between said air treatment segments (12), the conveying surface (11) of which is not facing the blowing openings (21), nor is it subjected to an airflow directed against said conveying surface (11), and said drying plant comprising a plurality of said idle segments (13) intercalated between a plurality of air treatment segments (12) along the direction of conveyance.

2. The drying plant according to claim 1, wherein the characteristics of the treated air are selected from: a relative humidity comprised between 5% and 25%; a temperature comprised between 30° and 50°; a speed of treatment of the treated air greater than 1.5 m/s.

3. The drying plant according to claim 1, wherein the characteristics of the air surrounding the idle segments (13) are selected from: a relative humidity greater than the relative humidity of the treated air; a temperature lower than the temperature of the treated air, the temperature of the treated air being higher than the temperature of the cut-up food fed included in the drying plant, or a temperature higher than the temperature of the treated air, the temperature of the treated air being lower than the temperature of the cut-up food included in the drying plant.

4. The drying plant according to claim 1, wherein the conveyor (10) is selected from: a conveyor with superimposed levels; a perforated conveyor with superimposed levels; a spiral conveyor with superimposed levels; a perforated spiral conveyor with superimposed levels.

5. The drying plant according to claim 4, wherein said plurality of blowing conduits (20) are arranged intercalated between said superimposed levels of the conveyor (10) or of the spiral conveyor.

6. The drying plant according to claim 5, wherein said conveyor includes straight segments of the conveyor arranged in superimposed levels, and wherein said blowing conduits (20) include straight blowing conduits superimposed to said straight segments of the conveyor, said straight segments of the conveyor forming the air treatment segments (12).

7. The drying plant according to claim 6, wherein said conveyor (10) includes superimposed curved conveyor segments, and wherein said curved conveyor segments lack blowing conduits (20) provided with blowing openings (21) intercalated between said superimposed curved conveyor segments, said curved conveyor segments forming the idle segments (13).

8. The drying plant according to claim 1, wherein the face provided with blowing openings (21) of at least one blowing conduit (20) of said plurality of blowings conduits (20) is parallel to the conveying surface (11) of the segment of the conveyor facing said surface, said at least one blowing conduit (20) being elongated in a direction parallel to the direction of conveyance of the segment of the conveyor (10) facing said conduit.

9. The drying plant according to claim 1, wherein at least one segment (10) of a blowing conduit (20) of said plurality of blowing conduits (20) has a constant width and a variable section decreasing in the direction of air circulation through the inside thereof.

10. The drying plant according to claim 1 wherein the features of the conveyor are selected from the following: each of said air treatment segments (12) has a length, in the direction of conveyance, greater than five meters; each of said idle segments (13) has a length, in the direction of conveyance, greater than five meters; the length of at least one idle segment (13) is comprised between 40% and 60% of the length of the air treatment segments (12) preceding, in the direction of conveyance, said at least one idle segment (13).

11. The drying plant according to claim 1, wherein suction conduits (22) are arranged adjacent to the air treatment segments (12), the air absorbed by said suction conduits (22) being used for obtaining said treated air.

12. The drying plant according to claim 11, wherein at least part of said suction conduits (22) are located in the limits between the air treatment segments (12) and the idle segments (13).

13. An air-drying method for air drying cut-up food, said method being applied by means of a plant including: a conveyor (10) for cut-up food (1) defining a conveying surface (11) and a direction of conveyance; a plurality of blowing conduits (20) including blowing openings (21) channeling a treated airflow with a temperature comprised between 4° C. and 60° C. and a controlled humidity; the method being characterized in that it comprises the following steps: a) feeding cut-up food (1) to said conveying surface (11) of the conveyor (10); b) conveying, by means of the operation of the mentioned conveyor (10), said cut-up food (1) to an air treatment segment (12) facing said blowing openings (21), said cut-up food (1) being arranged facing said blowing openings (21) of said blowing conduits (20); c) subjecting said cut-up food (1) to a drying treatment by means of a flow of said treated air directed against said conveying surface (11) of the air treatment segments (12) at a speed of treatment, directly affecting the cut-up food (1) for a drying time, causing moisture reduction in the outermost layer of said cut-up food (1); d) conveying, by means of the operation of the mentioned conveyor (10), said cut-up food (1) to an idle segment of the conveyor (10), said cut-up food (1) being exposed to a surrounding air lacking an airflow directed against said conveying surface for an idle time, causing rehydration of the outermost layer of the cut-up food with the internal moisture of the cut-up food, tending to achieve a homogeneous moisture in the cut-up food as a whole; e) repeating steps b), c) and d) cyclically, along a succession of a plurality of air treatment segments (12) and idle segments (13) that are intercalated, until achieving specific drying of the cut-up food (1).

14. The method according to claim 13, wherein the conveyor moves the cut-up food (1) at a constant and uniform speed.

15. The method according to claim 13, wherein the ratio between drying time and idle time is between 40% and 60%.

16. The method according to claim 14, wherein the ratio between drying time and idle time is between 40% and 60%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] The foregoing and other advantages and features will be better understood based on the following detailed description of an embodiment in reference to the attached drawings which must be interpreted in an illustrative and non-limiting manner, in which:

[0066] FIG. 1 shows a schematic perspective view of a drying plant for drying cut-up food provided with a spiral conveyor with sixteen superimposed levels each provided with two straight segments and two end curved segments, and including blowing conduits intercalated between the straight segments of said superimposed levels and suction conduits arranged adjacent to said conveyor;

[0067] FIG. 2 shows a schematic plan view of the conveyor shown in FIG. 1, devoid of the blowing and suction conduits;

[0068] FIG. 3 shows an enlarged cross-section of a plurality of superimposed levels of the conveyor, corresponding to a section of the corresponding air treatment segments, where blowing conduits interposed between the levels of the conveyor provide a treated airflow in a downward direction on each of the air treatment segments through blowing openings provided in said blowing conduits;

[0069] FIG. 4 shows an enlarged cross-section of a plurality of superimposed levels of the conveyor, corresponding to a section of the corresponding idle segments, where the cut-up food is not subjected to any treated or untreated airflow, allowing rehydration of the outermost layer of the cut-up food by means of migration of the internal moisture of said cut-up food.

DETAILED DESCRIPTION OF AN EMBODIMENT

[0070] According to a non-limiting, illustrative embodiment of the present invention, FIG. 1 shows a drying plant for drying cut-up food 1 consisting of a conveyor 10 in the form of a spiral conveyor with superimposed levels, each level integrated by a first straight segment, connected at one end to a first curved segment, attached in continuity to a second straight segment, and connected in turn to a second curved segment.

[0071] Each of said segments is slightly inclined, such that upon completing a complete turn, the final end of the conveyor 10 of one level is above the initial end of said level, and coinciding with the initial end of the next level, in the direction of conveyance. By connecting a plurality of levels at their initial and final ends, said spiral conveyor 10 with superimposed levels having a notable length and taking up a small volume is obtained.

[0072] Optionally, a plurality of spiral conveyors 10 with superimposed levels can be connected such that the cut-up food 1 goes through said plurality of spiral conveyors 10 before completing treatment.

[0073] The mentioned conveyor 10 can consist of conveyor belts defining a conveying surface, or sliding or tray driving mechanisms, which define said conveying surfaces on which the cut-up food 1 fed to the described air drying plant is deposited.

[0074] The aforementioned straight segments of the conveyor 10 have an approximate length of between 8 and 12 meters, and have respective conveying surfaces 11 facing blowing openings 21 provided in blowing conduits 20 intercalated between the superimposed levels of the conveyor 10, such that said straight segments define air treatment segments 12 for treatment of the cut-up food 1, as it is exposed to an upward or downward flow of treated air driven through said blowing openings 21. In the present embodiment, the blowing conduits 20 intercalated between the straight segments of the conveyor 10 are straight conduits extending in a direction parallel to the direction of conveyance of the conveyor 10, as can be seen in FIG. 3.

[0075] The blowing conduits 20 are connected to air treatment devices, not shown in FIG. 1, such as for example, heating machines, coolers, heat exchangers, dehumidifiers, etc, which allow providing and driving through said blowing conduits 20 a controlled flow of treated air the temperature and humidity of which are controlled, the controlled temperature being comprised between 4° C. and 60° C. and a controlled humidity, although the temperature will preferably be between 30° and 50° C. and the humidity less than 30%, for example comprised between 5% and 25%.

[0076] In the embodiment shown, four initial blowing conduits 20 not intercalated between levels of the conveyor are each divided into eight blowing conduits 20 intercalated between superimposed levels of the conveyor 10, providing a total of thirty-two air treatment segments 12, each facing a blowing conduit 20, corresponding to sixteen superimposed levels.

[0077] In contrast, the conveying surface 11 of the aforementioned curved segments of the conveyor will likewise have an approximate length of between 8 and 12 meters measured along their axis; it is not facing the blowing openings 21, so the conveyed cut-up food 1 is not subjected to a treated airflow in said segments, the air surrounding said curved segments being air with a humidity greater than the humidity of the treated air, and preferably having a temperature different from the temperature of the treated air, said curved segments defining idle segments 13 of the cut-up food 1, shown in a cross-section view in FIG. 4.

[0078] For example, if the temperature of the treated air is comprised between 30° C. and 60° C., and the temperature of the cut-up food is lower than the mentioned 30° C., the temperature of the air surrounding the idle segments will be lower than the temperature of the treated air. Likewise, if the temperature of the treated air is, for example, comprised between 4° C. and 15° C., and the temperature of the cut-up food is higher than the temperature of the treated air by 5° C., for example, then the temperature of the surrounding air will be higher than the temperature of the treated air.

[0079] Therefore, said conveyor 10 alternates air treatment segments 12 with idle segments 13, corresponding respectively to straight and curved segments of the conveyor.

[0080] This construction which has been described is simple as it does not require curved, more complex blowing conduits which are arranged facing the curved segments of the conveyor.

[0081] In the air treatment segments 12, the treated airflow strikes the conveyed cut-up food 1 deposited on the conveying surface 11 uniformly, such that said treated airflow dries the outermost layer of said cut-up food 1, stripping off and entraining its surface moisture by means of said airflow. Once said outermost layer reaches a certain degree of drying, it prevents the treated airflow from being able to cause the correct drying of the innermost layer of the cut-up food 1, since the already dry outermost layer cannot continue to be dried more, and its thickness prevents the treated airflow from causing the drying of the innermost layer of the cut-up food 1.

[0082] To prevent this phenomenon, it is proposed to arrange idle segments 13 intercalated between the air treatment segments 12. In said idle segments 13, there is no treated airflow striking the cut-up food 1, and therefore no additional drying of the outermost layer in said idle segments 13. In contrast, the moisture contained in the cut-up food 1 tends to be distributed homogeneously, so in the idle segments 13 said moisture has time to migrate from the innermost layer towards the previously dried outermost layer, thereby causing the drying of the innermost layer reducing its moisture content and rehydrating the outermost layer from the inside.

[0083] After that step, the cut-up food 1 is again carried to an air treatment segment 12 where the treated airflow again dries the outermost layer of the cut-up food 1.

[0084] This method can be repeated as many times as necessary until achieving an optimum degree of drying of the cut-up food 1 as a whole.

[0085] Along with the air treatment segments 12 there are arranged suction conduits 22 suctioning the surrounding air which, for the most part, will be previously treated air driven through the blowing openings 21, and which will have absorbed part of the moisture of the treated food 1.

[0086] Preferably, said suction conduits 22 will be connected to the air treatment devices providing the treated air, such that part or all of the air suctioned through the suction conduits 22 can be reused as treated air, and/or part of the energy contained in said suctioned air can be recovered, for example, by means of heat exchangers.

[0087] Similarly, a method is proposed which consists of alternating the treatment of the cut-up food 1 by means of a treated airflow applied in air treatment segments 12 of a conveyor 10, and by means of conveying the cut-up food 1 in idle segments 13 where there is no airflow, these steps being repeated cyclically until achieving the desired degree of drying of the cut-up food. The speed of conveyance of the cut-up food will preferably be constant.