FR2820814A1 - METHOD, DEVICE AND INSTALLATION FOR DESICCATION OF PACKAGED PRODUCTS SUCH AS FORAGE BALLS - Google Patents

Abstract

The invention relates to a method and an installation for the desiccation, by circulation of hot air, of packaged products (1). The method is characterized in that it consists in placing the product (1) packaged to dry in a sealed tubular casing (2) and closing one end of the casing (2) by a device (3) for supplying hot air, and the other end of this envelope by an air suction device (7) so as to impose the path of the air flow, through the packaged product according to preferably selectable paths to obtain drying homogeneous and complete in the mass of the product to be dried. Application: Drying of forage bales.

Description

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The present invention relates to a method, a device and an installation for the drying by circulation of hot air, possibly dried, of conditioned products such as bales of fodder. , bags of cereal or other.

It has always been known that the fodder must, before storage, be subjected to a drying stage to prevent, during storage, a fermentation which would alter the palatability, the nutritional quality and the shelf life of the fodder by generating in particular a development of the bacterial or viral contamination of the fodder and a putrefaction of the latter prejudicial to the animals fed by means of this fodder.

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As a result, haying has been practiced for many years, a traditional method of drying fodder on the meadow. However, this method is limited to regions in which the climatic and meteorological conditions allow it.

In addition to this natural method, industrial fodder drying processes and installations have been developed. These dryers apply more particularly to the drying of shaped fodder in the form of cylindrical or parallelepiped bales.

The purpose of these dryers is to dry the fodder until a relative humidity level in the range 13 - 18% is obtained in order to avoid all the aforementioned fermentation and putrefaction problems.

Two types of drying installation can therefore be distinguished. A first family of installations consists in blowing air through the ball of fodder. An example of such an installation is thus described in patent EP-A-534382. In this document, the installation comprises at least one ventilation chamber provided with two axial openings on which can be positioned each time the flat face of a ball to be dried. A stream of dry air is thus expelled through the axial ventilation openings of the chamber to pass through the mass of the ball and thus dry it. This current of hot air is produced by a centrifugal fan connected to a radial inlet of the ventilation chamber.

The main drawback of such an installation is an irregular distribution of dry air inside the mass of the bale. This results in non-uniform drying of the

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 fodder due to air losses caused by preferential passages of the air flow which occur inside the bale due to the lack of uniformity of the latter. This also results in considerable energy losses and an extension of the drying time.

The installation, described in international application WO-9740330, has the same drawbacks as those described above due to the use again of air blown from a ventilation chamber to pass through the mass of the ball. It has thus been found that such installations are unable to dry forages having an initial relative humidity rate greater than 45%, except when considering very long or even imperfect drying.

A second family of installations, to which the installation object of the present invention belongs, no longer uses a flow of air blown through the bale but sucked through the bale as drying means. This is the case of the installation described in US-A-4,640,021. This installation, designed to dry bales positioned in the form of a heap of generally parallelepipedal appearance, includes a mobile drier capable of being positioned against an end face of the bunch of bales. A flexible sheet, impermeable to air and humidity, covers the dryer and the pile of bales, keeping free the end face opposite to that against which the dryer is applied. A fan coupled to the dryer allows air to be drawn through the pile of bales from the open end of it and to evacuate this air

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 from the dryer in the atmosphere. The major drawback of such an installation resides in the impossibility of imposing on the air flow traversing the mass of products a predetermined and possibly selectable trajectory due to the maintenance in the open air of one of the faces of the ball. Furthermore, nothing prevents sucking in air with a high moisture content so that an effect contrary to that desired is obtained. Finally, the suction in an essentially horizontal direction harms the drying yield obtained and increases the energy consumption.

The object of the present invention is therefore to propose a method and an installation for the drying by circulation of hot air of packaged products, such as bales of fodder, whose designs allow to dry in a short time products whose rate initial relative humidity may be greater than 65% humidity.

Another object of the present invention is to provide a method and an installation of the aforementioned type, the designs of which allow uniform, homogeneous and complete drying of the bale while avoiding the formation of zones generally neglected by traditional drying treatments.

Another object of the present invention is to provide a method and an installation of the aforementioned type, the designs of which make it possible to select at will the trajectory of the flow of hot air, circulating inside the ball, so as to favor, in first, a

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 passage of air flows at the periphery of the bale without generating air dispersion.

Another object of the present invention is to provide a method and an installation of the aforementioned type which are simple to implement, manufacture and install and whose designs allow better use of energy and thus lower consumption.

To this end, the subject of the invention is a process for the drying, by circulation of hot air, of packaged products such as fodder bales, bags of cereals or the like, characterized in that it consists in placing the product conditioned to dry in a sealed tubular envelope and to close one end of the envelope by a device for supplying hot air, and the other end of this envelope by an air suction device so as to impose the path of the hot air flow, through the product conditioned according to trajectories, preferably selectable, to obtain a homogeneous and complete drying of the mass of the product to be dried.

Thanks to the use of a tubular casing cooperating with an air supply device and an air suction device to form a sealed enclosure subjected to permanent vacuum, the products to be dried are isolated from the outside environment and a effective drying of the bale is obtained thanks in particular to a possible selection of the air flow paths.

The invention also relates to a device for the

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 drying, by circulation of hot air, of conditioned products such as bales of fodder, sacks of cereals or others, characterized in that in operating mode, it consists of a tubular drying enclosure with vertical axis or horizontal closed at one of its ends by a hot air supply device, and at its other end by an air suction device so as to create inside the enclosure a permanent depression forcing the air flow to cross, according to prescribed paths, the entire mass of product to be dried without dispersing effect.

Such a device allows by design to dry in a short time products whose initial relative humidity can exceed 65%.

The invention also relates to an installation for the implementation of the above drying device, characterized in that it is in the form of a plurality of drying devices distributed around a central telescopic column for supplying hot air, carrying by means of radiating arms the hot air supply devices, or respectively suction devices which carry envelopes forming skirts constituting the drying chambers so as to simultaneously allow the covering of the masses of products to each resting on a suction device or an air supply device respectively arranged each time directly above the air supply device or respectively of the device

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 suction.

The invention will be clearly understood on reading the following description of exemplary embodiments, with reference to the appended drawings in which: FIG. 1 represents a schematic sectional view of a drying device according to the invention; Figure 2 shows a top view of an air supply tray; 3 shows a bottom view of a suction plate of the suction device and Figure 4 shows a schematic front view of an installation incorporating at least two desiccation devices according to the invention.

The device, object of the invention, is more particularly intended for the drying of packaged products 1. It can be applied to products with a high moisture content such as green grass or others. Such a device allows in particular the implementation of the above method.

This device is, in operating mode, constituted by a tubular drying enclosure 2A with vertical or horizontal axis, closed at one of its ends by a device 3 for supplying hot air, and at its other end by a air suction device 7. he

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 the result is the creation of a sealed enclosure inside which a permanent vacuum forces the air flow to cross, according to imposed trajectories, the entire mass of products to be dried without dispersing effect. In fact, the tubular drying enclosure 2A is preferably produced by means of a tight tubular casing 2 made of flexible material so that, under the effect of the depression generated by the suction device, it is pressed against the peripheral mass of the product 1.

The enclosure air supply device 3 must allow the enclosure to be supplied with unpolluted air. To do this, one or more filters may be arranged at the inlet of the air supply device 3.

The air supplying the enclosure 2A is preferably hot air having a temperature close to 55. To this end, an air or water exchanger (not shown) can be provided upstream of the device 3 for supplying air to the enclosure to allow this air to be heated.

To keep the air temperature substantially constant, the temperature delta between the temperature of the outside air and the temperature of the drying air is constantly taken into account. Air flow regulation means are controlled according to this variation. Likewise, additional air drying devices (not shown) can be provided upstream of this air supply device 3.

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This air supply device 3 is, as shown in Figures 1 and 2, consisting of a plate 4 having an inlet 5 of hot air, opening into the hollow body of the plate 4. The bottom of the plate 4 is provided peripherally of air passage openings 6 opening into the enclosure 2A. Thanks to the arrangement of these openings 6, it is possible to distribute the majority of the air at the periphery of the product to be dried. It is found, in fact, that this supply of air at the periphery is particularly important for obtaining an efficient and rapid drying of the product to be packaged. The heating, filtration and possibly additional air drying devices will therefore be provided upstream of the opening of the air inlet 5 or in this air inlet 5.

The suction device 7 is in turn in the general form of a hollowed-out plate 8 comprising concentric air passages 9 capable of being placed under vacuum alternately or simultaneously using a selector register 10. A design of these concentric air passages 9 is provided by way of example in FIG. 3.

The presence of a selector register 10 makes it possible to favor either the formation of a peripheral aspiration flow or the formation of a central aspiration flow, or a simultaneous peripheral and central aspiration. This selector register 10 can be actuated manually or automatically, for example by means of a rack or pinion system.

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This register 10 can be constituted, by way of example, of two crenellated, concentric crowns 10A, 10B capable of being driven by a relative displacement to force the formation of a peripheral and / or central flow. This register 10 may also consist of a movable drawer. Other embodiments of this register can also be envisaged.

As the figures show, the concentric air passages 9 of the suction plate 8 have their concentrated suction surface, preferably at the periphery of the mass 1 to be dried, so as to cover at the periphery at least 50% of the peripheral surface of mass 1 to be dried.

The inventors have in fact found that a passage at the periphery of the air flow was fundamental for obtaining rapid and efficient drying of the mass 1 of dried product.

The orientation of an air flow towards the center of the mass does not take place until a second time when a significant part of the moisture contained in the mass 1 of the product to be dried has been eliminated.

The suction device 7 can be put under vacuum via a vacuum cleaner 12 linked to the latter.

The vacuum cleaner 12 can for example consist of a suction turbine. Obviously, this turbine must have sufficient power to obtain a significant low pressure regime, preferably at least equal to 150 mm of water. Temperature and humidity sensors, placed in the vicinity of the suction device and the air supply device, allow monitoring of the

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 operation of the desiccation installation and help in the choice of the air flow paths inside the said enclosure.

Although, in the examples shown, the air supply device is located at the top of the enclosure 2A, while the suction device 7 is located at the bottom of this enclosure 2A, a reverse solution can also be considered. Similarly, when the enclosure is on a horizontal axis, the air supply device and the suction device are located at each end of the enclosure.

In any event, the enclosure 2A, when it has a vertical axis, will preferably be integral with the suction device 7 or respectively with the air supply device 3 located at the top of the enclosure 2A.

This arrangement allows the enclosure 2A to cap, when loading the device, the mass of products 1 to be dried. This results in a quick and easy loading of the device with an easier installation of the enclosure 2A around the mass of the product 1 to be dried.

The connection between the envelope 2 constituting the enclosure 2A and the suction device 7 or respectively the supply device 3 may be made by any means ensuring a sealed connection between said elements.

To complete the desiccation of such products, it is

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 provided, at the periphery of the suction device 7, an annular passage 11 projects beyond the volume occupied by the product 1 to be dried in the enclosure 2A to force part of the drying flow to pass through the base peripheral portion of the product 1 to dry. Indeed, it is often found, in traditional installations known from the state of the art, that this part of the product 1 to be dried can be still loaded with moisture even after the drying process and therefore present problems of product conservation .

The objective of this annular passage 11 is therefore to create, by a venturi effect, a depression at the level of this sensitive part of the product 1 to be dried in order to obtain an effective drying of the latter.

The device described above can be inserted in an installation comprising several devices of the aforementioned type so as to allow the drying of several packaged products 1 in parallel. In this case, the installation in accordance with that shown in FIG. 4 is in the form of a plurality of desiccation devices distributed around a central telescopic column 13 for supplying dry air. This central column 13 is provided at its upper end with radiating arms 14 carrying, in the examples shown, the devices 3 for supplying dry air, which carry envelopes 2 forming skirts constituting the drying chambers 2A.

Thus, when the telescopic column is actuated, it is possible to cover the masses 1 of

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 products to be dried based on none on an air suction device 7, each time placed directly above the air supply device 3.

Obviously, a reverse solution consisting in placing the suction devices 7 in the upper part of the column and, conversely, the air supply devices 3 directly above the suction device 7 is also conceivable.

Such installations will generally be located in the vicinity of a technical room which will include all of the means, such as a boiler, engine or other necessary for the operation of said installation.

Such an installation makes it possible to obtain particularly effective drying yields with energy consumption remaining reasonable.

A variant using the same drying process is planned. In this variant, the balls are arranged in the superimposed state in the case of an enclosure with a vertical axis and side by side in the case of an enclosure with a horizontal axis.

Thus, the hot air enters through the first ball of the alignment or the stack in the enclosure, crosses all of the balls and is sucked past the last ball. This arrangement allows several balls to be dried simultaneously inside the same enclosure.

Claims (11)

CLAIMS 1. Process for the drying, by circulation of hot air, of packaged products (1) such as fodder bales, bags of cereals or the like, characterized in that it consists in placing the packaged product (1) to dry in a sealed tubular envelope (2) and to close one end of the envelope (2) by a device (3) for supplying hot air, and the other end of this envelope by a device (7) d air intake so as to impose the path of the air flow, preferably hot, through the product packaged according to preferably selectable paths to obtain a homogeneous and complete drying of the mass of the product to be dried. 2. Device for the drying, by circulation of hot air, of packaged products (1) such as bales of fodder, sacks of cereals or the like, characterized in that in operating mode, it consists of a tubular drying enclosure (2A) with horizontal or vertical axis closed at one of its ends by a device (3) for supplying hot air, and at its other end by a device (7) for air suction so as to create inside the enclosure (2A) a permanent depression forcing the air flow to cross, according to imposed trajectories, the entire mass of product to be dried without dispersing effect. 3. Device for drying products (1) packaged according to claim 2, characterized in that the device (3) supply <Desc / Clms Page number 15>  in hot air, consists of a tray (4) having an inlet (5) of hot air, opening into the hollow body of the tray (4), the bottom of said tray (4) being provided peripherally with openings (6 ) of air passage opening into the enclosure (2A). 4. Device for the drying of products (1) packaged according to one of claims 2 and 3, characterized in that the enclosure (2A) of tubular drying is produced by means of an envelope (2) tubular tight material flexible so that, under the effect of the vacuum generated by the suction device (7), it is pressed against the peripheral mass of the product (1). 5. Device for the drying of products (1) packaged according to one of claims 2 to 4, characterized in that the enclosure (2A) with vertical axis is integral with the device (7) for suction or respectively with the device ( 3) air supply located at the upper part of the enclosure (2A) so as to cap, when loading the device, the mass of product (1) to be dried. 6. Device for drying products (1) packaged according to one of claims 2 to 5, characterized in that the suction device (7) is in the general form of a tray (8) hollowed out comprising concentric air passages (9) capable of being depressed alternately or simultaneously using a selector register (10), to favor either the formation of a peripheral suction flow, the formation of a central suction flow, <Desc / Clms Page number 16>  or simultaneous peripheral and central aspiration. 7. Device for the drying of products (1) packaged according to claim 6, characterized in that the register (10) consists of two crowns (10A, 10B) crenellated, concentric, capable of being driven by a relative movement to force the formation of a peripheral and / or central flow. 8. Device for the drying of products (1) packaged according to claim 6, characterized in that the passages (9) of concentric air of the suction plate (8) have their suction surfaces concentrated preferably at the periphery of the mass (1) to be dried so as to cover at the periphery at least 50% of the peripheral surface of the mass (1) to be dried. 9. Device for the drying of products (1) packaged according to one of claims 2 to 8, characterized in that there is provided at the periphery of the device (7) a passage passage (11) annular, projecting relative to the volume occupied by the product (1) to be dried in the enclosure (2A), to force part of the drying flow to pass through the basic peripheral portion of the product (1) to be dried. 10. Device for the desiccation of products (1) packaged according to one of claims 2 to 9, characterized in that the device (7) of suction is put under vacuum by means of a vacuum cleaner (12) linked to the latter. <Desc / Clms Page number 17> 11. Installation for the implementation of the drying device according to one of claims 2 to 10, characterized in that it is in the form of a plurality of drying devices distributed around a column (13) telescopic central hot air supply, carrying by means of radiating arms (14) the hot air supply devices (3), or respectively the suction devices (7), which carry envelopes (2) forming skirts constituting the drying chambers (2A) so as to simultaneously allow the covering of the masses of products (1) to be dried each resting on a suction device (7) or respectively on an air supply device disposed at each times directly above the air supply device (3) or the suction device (7) respectively.