DESCRIPTION

The present invention relates to a dryer.

In particular, though not exclusively, the present invention relates to a dryer for granular or flaked materials.

In general, a dryer performs the task of reducing or eliminating the moisture present inside a product, as a residue of previous processings or production processes.

A dryer is substantially defined by a drying chamber, inside which a very hot and dry environment is created. The heat is produced by sources known in the sector, such as for example gas burners, and is distributed inside the drying chamber using forced air currents. Inside the drying chamber, the product is arranged resting on one or more shelves, fixed or motorised along a longitudinal direction, which promote the circulation of the hot air.

The product that exits from the dryer, at the end of the drying process, is at a relatively high temperature. In the majority of cases, and in particular in the case of granular or flaked products destined to be bagged, it is necessary to wait for the products to cool. This involves a lengthening of process times. Further, the product being cooled occupies space inside the plant. The object of the present invention is to provide a dryer which enables the drawbacks of the currently available drying chambers to be obviated.

The main further advantage of the dryer according to the present invention is that the exiting product does not require cooling, but is substantially ready for further processings, for example to be bagged.

A further advantage of the dryer according to the present invention is that it is compact and efficient.

Additional features and advantages of the present invention will become more apparent from the following detailed description of an embodiment of the invention, illustrated by way of non-limiting example in the appended figures, in which:

- figure 1 is a lateral view of the dryer according to the present invention;

- figure 2 shows a view from the left of the dryer of figure 1 , with a lateral wall removed to show the inside; - figures 3 and 4 show respectively a front view and a view from above of a first air circuit (4) of the dryer;

- figures 5 and 6 show respectively a front view and a view from above of a second air circuit (5) of the dryer.

The dryer according to the present invention comprises a drying chamber (2), inside which the drying process of the products takes place. The drying chamber, in a known way, is delimited by a casing that has at least one inlet opening (21) and at least one outlet opening (22).

The dryer comprises further two or more superposed shelves (3), for supporting the product(s) to be dried. The shelves (3) are preferably horizontal, but might also have a certain inclination with respect to the horizontal plane. The shelves (3) have a structure which promotes air circulation. The shelves (3) are motorised to enable the transport of the product along a longitudinal direction (X). The shelves (3) are arranged perpendicular to two lateral walls (2a, 2b) of the drying chamber (2); the lateral walls are parallel to the longitudinal direction (X).

In the represented embodiment, the shelves (3) are structured so that the product proceeds along the longitudinal direction (X), transiting on all the shelves (3). In particular, the shelves (3) are offset to enable the transfer by dropping the product from one shelf to the shelf below.

In practice, while entering the dryer, the product is fed into the upper shelf (3). The upper shelf (3) is arranged in an offset manner, in a retracted position with respect to the underlying shelf in the advancement direction of the product, so that the terminal end (3b) of the upper shelf (3) projects into the shelf below. This enables the product, dropping from the upper shelf, to deposit on the shelf below. To enable the passage by dropping of the product from each shelf (3) to the shelf below, each shelf has a terminal end (3b), in the advancement direction of the product, which projects onto the underlying shelf, and in particular on an inlet zone (3a). In the represented embodiment, the terminal and inlet zones (3a, 3b) are located immediately outside the drying chamber (2). The shelves (3) preferably have alternating advancement directions, i.e. each shelf has an advancement direction that is opposite with respect to the overlying shelf and the underlying shelf. The product, as it passes from one shelf to the underlying shelf, thus inverts the advancement direction thereof. In this way it is possible to contain the overall size of the dryer along the longitudinal direction (X).

The shelves (3) preferably comprise a plurality of through openings, to promote the flow of air. In the represented embodiment, at least one shelf (3), preferably each shelf (3), comprises a flexible element (31) made of a net or mesh structure.

The flexible element (31) is arranged in a loop along a closed path which has at least one straight upper section for supporting the product. The upper section is activated in movement along the longitudinal direction (X) in a predetermined direction. In the represented embodiment, the flexible element (31) is folded about at least two rollers (32), located with horizontal axes of rotation parallel to one another. At least one of the rollers is motorised. As shown in figure 2, the guide rollers of each flexible element (31) substantially define the ends of the relative shelf (3). Considering the advancement direction of each shelf (3), the terminal end of each shelf (3) projects onto an initial section of the underlying shelf (3), i.e. the roller arranged at the terminal end of the relative shelf (3) projects onto an initial section of the underlying shelf (3). The dryer according to the present invention comprises a first air circuit (4) for the introduction of hot air into the drying chamber. The first air circuit (4) comprises a main fan (41), connected to a delivery manifold (42). In a known way in the sector, the main fan (41) is provided with an air intake to suck in air which can be already heated, by means of a source located outside the dryer, or ambient air, in a case where the heating source is located inside the dryer. In any case, the main fan (41) can be connected to an air recirculation conduit, present inside the drying chamber (2), in a known way in the sector. The manifold (42) is connected to a plurality of delivery conduits (43), distributed inside the high temperature zone (21). Each delivery conduit (43) is provided with a plurality of outlet openings through which the hot air is introduced into the high temperature zone. In the preferred but not exclusive illustrated embodiment, the manifold (42) is positioned above the drying chamber (2). The delivery conduits (43) descend from the manifold (42) on substantially vertical planes. The delivery conduits (43) are preferably arranged at a lateral wall of the drying chamber (2). Preferably, though not necessarily, the delivery conduits (43) are subdivided into two groups that branch off from opposite zones of the manifold (42). The two groups of delivery conduits (43) are arranged on the opposite lateral walls (2a, 2b) of the drying chamber (2). This enables maintaining the manifold (2) in a centre of gravity position with respect to the drying chamber, and distributing the delivery conduits (43) in a substantially symmetrical way with respect to the manifold (42). In the represented embodiment, the first air circuit (4) comprises two fans (41) and two manifolds (42) that are independent of one another and flanked, each of which comprises its own delivery conduits (43). This enables a better distribution of the hot air.

The delivery conduits (43) comprise a transverse section (44) arranged substantially horizontal on a plane parallel to one of the shelves (3). The transverse section (44) of each conduit (43) is arranged substantially parallel above or below a shelf (3). For example, in the represented embodiment which comprises two shelves (3) in the high temperature zone (21), the delivery conduits (43) comprise two series of transverse sections (44), a first series located above the upper shelf (3) and a second series arranged above the lower shelf (3), i.e. between the upper shelf (3) and the lower shelf (3). The transverse portions (44) are preferably arranged coplanar on a same horizontal plane, and outlet openings are arranged facing downwards and/or facing upwards. Outlet openings facing downwards enable an effective dispensing of hot air towards the underlying shelf (3).

The dryer of the present invention advantageously comprises a high temperature zone (21) and a low temperature zone (22), separate from one another, of which the high temperature zone (21) is connected to the first air circuit (4). The low temperature zone (22) is located below the high temperature zone (21). The low temperature zone (22) is connected to a second air circuit (5), for the introduction of air at low temperature. By low temperature it is meant a temperature that is substantially the same as the ambient temperature, or in any case at a temperature considerably below the temperature present in the high temperature zone (21). When transiting through the low temperature zone (22), the product significantly cools down, reaching, for example, ambient temperature, and is therefore suitable to be immediately bagged or packaged in another way, or to be subjected to further processings, with no need to wait for a further cooling.

The low temperature zone (22) is provided with one or more shelves (3), entirely alike the shelves (3) of the high temperature zone (21). The shelves (3) are predisposed to enable the transport of the product through the high temperature zone (21) and then through the low temperature zone (22). In particular, the shelves (3) present in the low temperature zone (22) are located alike the shelves of the high temperature zone, to enable the passage of the product by dropping from each shelf to the underlying shelf. In substance, the upper shelf (3) of the low temperature zone (22) is located in such a way as to receive the product that drops from the terminal end of the lower shelf (3) of the high temperature zone (22). In other terms, the terminal end of the lower shelf (3) of the high temperature zone (21) projects onto the upper shelf (3) of the low temperature zone (22). In the represented embodiment, the low temperature zone (22) comprises only one shelf (3), which is also used to carry the product to an unloading zone outside the dryer. A dividing septum (W) is interposed between the two zones (21, 22) to enable thermal isolation, except for the openings necessary to allow the drop of the product from one to another. The second air circuit (5) comprises a main fan (51), connected to a delivery manifold (52). The main fan (51) of the second air circuit (5) is distinct from the fan (41) of the first air circuit (4), and the manifold of the second air circuit is distinct from the manifold of the first air circuit. In a known way in the sector, the main fan (51) of the second circuit (5) is provided with an air intake by suction of cooling air. For example, the cooling air is air at ambient temperature.

The manifold (52) is connected to a plurality of delivery conduits (53), distributed inside the low temperature zone (22). In the represented embodiment, the manifold (52) is in the form of conduit that descends, in proximity of a lateral wall of the drying chamber, from the delivery of the fan (51). At the low temperature zone (22), the manifold (52) is connected to a distributor section (53), substantially arranged horizontally and parallel to the longitudinal direction (X). A plurality of delivery conduits (54) branch off from the distributor section (53), arranged substantially horizontally on a parallel plane to the shelves (3).

In the represented embodiment, the low temperature zone (22) comprises only one shelf (3), which is the shelf located in a lower position with respect to the other shelves. The delivery conduits (54) are arranged on a plane overlying the shelf (3) of the low temperature zone (22), inside the low temperature zone (22). The delivery conduits (54) are provided with emission openings facing downwards and/or upwards, in order to introduce cooling air into the low temperature zone (22).

A suction circuit (6), visible in figure 2, is preferably connected to the low temperature zone (22). The suction circuit (6) comprises a suction fan (61), connected to a suction manifold (62) provided with one or more suction openings located in the low temperature zone. In the represented embodiment, the fan (61) is located above the drying chamber (2) and the suction manifold comprises a conduit which descends from the fan (61) along a lateral wall (2b).

The presence of the low temperature zone (22) separated from the high temperature zone (21), thus enables the product to be cooled to a desired temperature, for example to ambient temperature, so that the product is ready, already at the outlet of the dryer, for bagging or packaging in another way, or for any other processing that requires a temperature lower than the drying temperature.