EP1544561A1

EP1544561A1 - System for drying materials

Info

Publication number: EP1544561A1
Application number: EP03104707A
Authority: EP
Inventors: Patrizio Grando; Alberto c/o Costr. Meccaniche L. Pozzi SPA Pozzi
Original assignee: Pozzi Leopoldo SRL; RF Systems SRL
Current assignee: Pozzi Leopoldo SRL; RF Systems SRL
Priority date: 2003-12-16
Filing date: 2003-12-16
Publication date: 2005-06-22

Abstract

A system (1) for drying materials (M) is disclosed comprising: a hydroextraction station (2) consisting of at least a hydroextraction device (3) provided with centrifugation means (4) of said materials (M); a drying station (5) consisting of a drying device (6) and radiofrequency means (21) adapted to generate an electric field into which the materials (M) to be dried are immersed; a plurality of material holders (8) in which the materials (M) to be dried are arranged; driving means (9) adapted to transfer the material holders with the materials (M) from the hydroextraction station (2) to the drying station (5).

Description

The present invention relates to a system for drying materials, particularly useful to dry textile fibres such as yarns.
It is well-known that many materials during or at the end of their conversion cycle should be dried.
For instance vegetable products such as hay, straw and the like before being ensiled must undergo a drying operation as well as textile products such as fabrics and yarns after the dyeing process.
In order to carry out said drying operations, drying cycles are for instance used, comprising a phase of mechanical hydroextraction of water by centrifugation, followed by a drying phase that can be carried out in hot air ovens or radiofrequency ovens.
A known method of drying yarns wound for instance as cones, provides for a hydroextraction phase by centrifugation, removing most water contained in the yarn, followed by a drying phase in a radiofrequency drier completing the drying operation bringing the yarn to the desired humidity rate.
The main drawback of this drying method consists in that the devices carrying out the centrifugal hydroextraction and the radiofrequency driers have different material processing times.
Indeed, while the hydroextraction phase is rather quick, the radiofrequency drying phase is much longer because it is not possible to reach too high radiance powers that could damage yarn.
Moreover, the radiofrequency drier requires a great working surface to distribute the active power on a big quantity of material to be treated.
For this reason in order to balance the two treatments it is necessary to create intermediate storage of centrifuged material ready to load the drying devices.
A first drawback consists in that, in addition to the considerable space requirement for the equipment and the intermediate storage, it is necessary to carry out repeated movements of the material from the area where the centrifugation devices are arranged to the area where the drying devices are mounted, that could be away even several metres from each other.
Another drawback consists in that the presence of intermediate storage of semifinished material involves also the cost of material immobilization.
A last, but not least, drawback consists in that one should take into account in the cycle-time also the time of unloading each centrifugation device and loading each drying device that, besides involving an increase of the crossing-time of the departments, causes also an increase of costs for the greater labour required or for the installation of automatic moving equipments.
The present invention aims at overcoming said drawbacks.
More particularly, a first object of the invention is to provide a drying system carrying out the treatment of hydroextraction by centrifugation, in an automatic sequence with the radiofrequency drying treatment.
Another object is to provide a system allowing a greater output in comparison with equivalent systems of known type, the used space being equal.
A last, but not least, object is to improve the quality of the finished product in comparison with the treatments of the prior art.
The foregoing objects are attained by a drying system for materials that according to the main claim is characterized by comprising:

at least a hydroextraction station consisting of at least a hydroextraction device provided with centrifugation means for said materials;
at least a drying station consisting of at least a drying device and radiofrequency means adapted to generate an electric field into which said materials to be dried are immersed;
a plurality of material holders in which said materials to be dried are arranged;
and handling means adapted to transfer said material holders with said materials from each hydroextraction station to a corresponding drying station.

Preferably, according to the invention, the system comprises at least a loading station where the materials to be dried are placed in the material holder to be introduced into the hydroextraction device and at least an unloading station where the dried materials coming out from the drying station are unloaded from the material holder.
The drying operation with radiofrequency heating occurs preferably with a frequency comprised between 5 and 50 MHz and under vacuum so as to lower the processing temperature.
Thus the advantage is obtained, to transfer more power to the product and therefore to dry it in a quicker way without damage.
More particularly, the system is used to dry yarns arranged in cones or tubes loaded on a material holder having such features to make easier the mechanical hydroextraction actions and allow during the radiofrequency drying phase, the generation of a dynamic vacuum condition through the material being treated.
Advantageously, the drying system of the invention allows to obtain a dried product in less time and of better quality relative to systems of the prior art.
Still advantageously, the system of the invention is more economical relative to the systems of the prior art because it reduces the cycle-time and the handling operations of the materials between the devices and the loading and unloading stations as well as the floor room required by the equipments.
Also advantageously the intermediate storage between the devices is eliminated so as to reduce the immobilization cost of semifinished material.
The foregoing objects and advantages will be better understood by the description of a preferred embodiment of the invention which is given as an illustrative, but non-limiting example, making reference to the accompanying sheets of drawings in which:

Figure 1 is a top view of the system of the invention;
Figure 2 is a left-hand side view of the system of Figure 1 along the direction II-II;
Figure 3 is a sectional view taken along the plane III-III of the system of Figure 1;
Figure 4 is an enlarged longitudinal section of the material holder shown in Figures 2 and 3;
Figure 5 is a detail of the material holder of Figure 4;
Figure 5a shows the detail of the material holder of Figure 5 in a different working position;
Figure 5b shows a constructional variation of the detail of Figure 5a to receive cones wound on cylindrical tubes;
Figure 6 shows the material holder of Figure 4 with the materials to be dried loaded on it; and
Figure 7 shows a detail of the material holder of Figure 6.

The material drying system of the invention is generally indicated with numeral 1 in Figures 1 to 3 where it is shown in three different views.
One can see that the system comprises:

a hydroextraction station generally indicated with numeral 2, consisting of a hydroextraction device 3 provided with centrifugation means 4 for the materials to be dried;
a drying station generally indicated with numeral 5, consisting of a drying device 6 and radiofrequency means 7 adapted to generate inside the device 6 an electric field into which the materials to be dried are inserted;
three material holders each generally indicated with 8, on which the materials M to be dried are arranged;
handling means generally indicated with numeral 9, adapted to transfer each material holder 8 with the materials M arranged thereon, from the hydroextraction station 2 to the drying station 5

Preferably, but not necessarily, the operation frequency of the drying station is comprised between 5 and 50 MHz.
The system comprises also a loading and unloading station generally indicated with numeral 10, from which the handling means 9 take the material holders 8 that should be placed at the hydroextraction station 2 and in which the same handling means 9 put down the material holders 8 taken at the drying station 5. At the loading and unloading station 10 the operator O first unloads from the material holder 8 the materials M that already underwent the drying process at the station 5 and then loads on the same material holder 8 other materials M that should undergo the hydroextraction process at the hydroextraction station 2.
The drying station 5 comprises also suction means generally indicated with 11, that are connected with the drying device 6 and particularly with the material holder 8 to put it under vacuum during the material-drying treatment.
It is to be pointed out that the embodiment of the system which is now described with reference to the drawing, is simply illustrative of a possible embodiment providing for a hydroextraction device 3, a drying device 6 and a loading and unloading station 10.
Other non-illustrated constructional forms may provide for any number of hydroextraction stations 3 and drying stations 5, each comprising any number of devices.
Moreover, the loading and unloading stations instead of being coincident, may be separate from each other and divided into loading stations arranged upstream the hydroextraction devices and unloading stations arranged downstream the drying stations.
In a similar way the suction means 11 may be of any number, but not necessarily equal to the number of drying devices to be put under vacuum.
As to the hydroextraction station 2, the hydroextraction device 3 comprises a container 12 that can be closed by a lid 12a, inside which centrifugation means generally indicated with 4 are arranged.
Discharge ducts convey the extracted water outside the device.
The centrifugation means 4, with particular reference to Figure 3, comprise a basket 14 with perforated lateral surface 15, provided with a bottom 16 mechanically connected to driving means generally indicated with 17, adapted to put it into rotation around a vertical axis X defined by a central core 18 rising from said bottom 16.
As to the drying station 5, the drying device 6 comprises a container 19 that can be closed through a lid 19a, inside which there are armatures generating an electric field, generally indicated with 20, electrically connected to a radiofrequency generator 21 jointly constituting the above-mentioned radiofrequency means generally indicated with 7.
More particularly said armatures 20 are made of conductive materials and comprise a central core 22 coaxially arranged inside the container 19 defining a vertical axis Y and one or more curved plates 23 arranged in proximity of the walls of the container 19 with the concavity 23a facing the central core 22.
The central core 22 is generally grounded while the curved plates 23 are electrically connected to the radiofrequency generator 21; in a different installation embodiment the curved plates could be grounded or be integral with the container 19, while the central core could be electrically connected to the radiofrequency generator.
Between the central core 22 and the curved plates 23 an electric field is created, into which the material M is immersed when the material holder 8 is inserted in the drying device 6.
In said drying device 6 there are rotation means generally indicated with 24, comprising a support plane 25 for the material holder 8, mechanically connected to driving means generally indicated with 26, adapted to put it into rotation around the vertical axis Y defined by the central core 22.
The central core 22 as shown in Figure 3, is internally hollow and is in communication through a duct 27 with the above-mentioned suction unit 11 consisting of a vacuum pump 11a.
As far as the material holders 8 are concerned, one of them being shown in an enlarged view in Figure 4, each holder consists of a tubular body 28 with mainly longitudinal development, from which support arms, each generally indicated with numeral 29, for the materials M to be dried are projecting.
More particularly, each support arm 29 shown in Figures 5, 5a comprises a first tubular member 30 peripherally fixed to the tubular body 28 and a second tubular member 31 telescopically and slidingly coupled to the first tubular member 30.
At the end of the second tubular element 31 there is a swinging support generally indicated with 32, bearing the material M to be dried.
Between the first tubular member 30 and the second tubular member 31 a sealing sliding coupling is so obtained that the suction produced by the suction unit 11 inside the tubular body 28 through the duct 27, is delivered also to the duct 29a defined between the tubular members 30 and 31 and reaches inside the swinging support 32 supporting the material M to be dried.
Said swinging support 32 comprises, as shown in the detailed views of Figures 5, 5a and 7, a perforated conical support 33 with a base 33a coupled in a conical seat 34 made in the second tubular member 31.
The base 33a is freely coupled inside the seat 34 so that the perforated support 33 may swing in both directions of the arrow indicated with 35 in order to orient the material M to be dried arranged on it during the centrifugation.
More particularly, the perforated support 33, initially arranged vertically and retracted as shown in Figure 5a, during the centrifugation phase is moved in an inclined and projecting position as shown in Figure 5 and then returns again in the configuration shown in Figure 5a during the radiofrequency drying phase under the action exerted by suction on the second tubular member 31.
As far as the material M to be treated is specifically concerned, it consists of a cone formed by yarn wound on a perforated conical tube T coaxially coupled externally to the perforated conical support 33.
A constructional variation of the perforated support is provided, having a cylindrical surface as shown in Figure 5b, where it is generally indicated with numeral 33a, which is used when the yarn is wound on a cylindrical tube instead of a conical one.
At the top of the perforated conical support 33 or the cylindrical support 33a, there is a special shaped cap 51 performing the vacuum-tight action against the tube T.
It is, however, clear that the particular shape of the described material holder is conditioned by the fact that the material to be dried is a yarn wound as cones.
When the material to be treated is of a different kind or wound in a different way, (for instance tops), obviously the material holder should be made according to different geometrical configurations relative to those described and anyway adapted to receive the material in the most suitable way to allow suction through said material.
As to the driving means that in Figures 1 to 3 are generally indicated with 9, one can see that they essentially comprise a vertical column 35 defining a vertical axis Z to which a moving arm 36 is associated, provided at the ends with a hooking means 37 of a corresponding material holder 8.
More particularly, one can see that the driving means comprise:

rotation means generally indicated with 38, adapted to rotate the arm 36 around the vertical axis Z of the column 35;
translation means generally indicated with 39, adapted to move the arm 36 longitudinally to the column 35 along the vertical axis Z.

As to the load and unload station 10, as shown in Figure 2, it is provided with rotation means of the material holder 8, generally indicated with 40 and practically equal to those provided in the drying device 6, comprising a support plane 41 rotated by driving means 42 around a vertical axis K defined by a central core 43 vertically rising from the support plane 41.
Operatively the drying-cycle start when the material holder 8 with reference to Figure 1, is arranged at the loading station 10 supported by the rotation unit 40.
In this position the operator O loads the cones M to be treated on the material holder 8 which is put into rotation around the axis K by the rotation unit 40 to make easier the work of the operator O.
When loading is completed, the material holder 8 is lifted vertically by the arm 36 that is moved upwards along the column 35 by the intervention of the translation means 39.
During the upward movement, the arm 36 lifts at the same time also the material holders 8 inside the hydroextraction device 3 and the drying device 6, in which the previously loaded materials underwent the hydroextraction and drying treatments respectively.
One can see that during the lifting of the arm 36, also the lids 12a and 19a are respectively raised from the hydroextraction device 3 and the drying device 6, which are fixedly secured to the hooking means 37 of the material holders.
The arm 36 is then put into rotation by the rotation means 38 in the clockwise direction indicated by arrow 45 so that at the same time:

the material holder 8 with the materials to be dried is arranged coaxially above the hydroextraction device 3;
the material holder 8 taken from the hydroextraction device 3 is arranged coaxially above the drying device 6; the material holder 8 taken from the drying device 6 is arranged coaxially above the rotation unit 40 of the loading and unloading station 10.

When the rotation is terminated, the intervention of the translation means 39 causes the arm 36 and the material holders 8 associated thereto to be vertically lowered so that at the same time:

the material holder 8 with the dried materials M is placed at the loading and unloading station 10;
the material holder 8 with the materials to be dried is inserted into the drying device 6;
the material holder 8 with the materials to be centrifuged is inserted in the hydroextraction device 3.

On lowering the arm 36, the closure of the device occurs as well, because the relevant lids are associated to the arm 36 as already mentioned.
The materials M treated and placed at the unloading station, are taken out from the corresponding material holder 8 which is then again loaded with fresh material to be treated. This cycle may be repeated indefinitely.
In order that the drying cycle occurs in an automatic sequence, it is indispensable that the loading and unloading time of the material holder by the operator corresponds to the centrifugation-time of the hydroextraction device 3 and the drying-time of the drying device 6.
In this way no station constitutes bottleneck for the working-cycle and the non-operative times are reduced only to the opening-time of the devices and change of the material holders.
Since the hydroextraction-time as already mentioned is lower than the drying-time, the balance of the time of these two operations is carried out adjusting the vacuum degree inside the drying device by using the suction means 11.
By increasing vacuum inside the drying device 6, the treatment temperature is lowered and this allows to increase the power that the radiofrequency generator delivers to the yarn that can therefore lose humidity in less time without damage.
Obviously, by calibrating properly the power delivered by the radiofrequency generator and the vacuum degree, it is possible to reduce the drying-time until it becomes coincident with the hydroextraction time by centrifugation.
As one can see in Figure 6, during centrifugation the second tubular member 31 of the material holder 8 slides telescopically and radially on the first tubular member 30 until the cone M is in contact with the perforated wall 15 of the rotary basket 14.
Moreover, the shaft 33 supporting the tube T of cone M, can be arranged inclined by the amount allowed by the inclination ^á of the conical profile seat 34 receiving its end 33a.
The inclination ^á of the conical profile seat 34 is indeed equal to the inclination ^á of the outer wall of the cone M so that its outer surface during centrifugation is substantially vertical and therefore in contact with the wall 14 of the rotary basket 4 as shown in Figure 6.
In this way, the wall 14 of the basket 4 exerts a mechanical containment action of the cone during centrifugation and avoids to damage the yarn while the perforation 15 allows passage of water which is being extracted by centrifugation.
When the material to be treated is yarn wound in cones with cylindrical tube as already mentioned, a perforated cylindrical support 33a will be used with an axis that cannot be inclined because during centrifugation the outer surface of the cone will be placed in contact with the inner surface of the basket 14 without requiring rotation of its axis.
With particular reference to the suction treatment as shown in Figure 3, it is carried out from inside the material holder 8 which is connected to the suction unit 11 through a duct 50.
Suction is started at the beginning of the radiofrequency-drying-cycle and through the tubular body 28 of the material holder 8 puts under vacuum the interior of the perforated supports 33 or 33a through the ducts 29a defined inside each support arm 29.
It is important to note that when the material holder is introduced in the container 19 for the radiofrequency drying operation, it has the support arms 29 arranged in the configuration shown in Figure 5, that is with the second tubular member 31 in the maximum extension position.
During the drying operation, the vacuum action generated by the suction means 11 causes the second tubular member 31 to retract gradually in the configuration shown in Figure 5a.
It is to be noted that during this movement the duct 29a defined inside the support arms 29 is tightly sealed so as to warrant that suction occurs only through the holes of the perforated supports 33 or 33a and therefore from inside the cones.
More particularly, suction occurs according to the flow indicated in Figure 6 in the direction of the arrows 52 from inside the container 19 to the interior of the material holder 8 passing through the entire body of the yarn constituting each cone M.
To this purpose it is important to note that the suction unit 11 does not create a static vacuum, but an active one because air and steam produced during the drying phase and extracted by the suction unit 11, are supplemented with air sucked from outside according to a continuous cycle allowing anyway to keep constantly under vacuum the drying device 6 during operation.
Therefore on the basis of the foregoing, it is to be understood that the system of the invention attains all the intended objects and advantages.
As already mentioned the system could be carried out also in forms other than those described and shown in the drawings, since it can consist of more stations, each provided in turn with several processing equipments.
Moreover, as a function of the number of devices and loading and unloading stations, the driving means for the material holders could be carried out in a form other than the described and illustrated one.
Moreover, the material holder may also undergo constructional modifications as a function of the material to be treated that has to be supported.
All the foregoing variations and other possible modifications that could fall within the scope of the appended claims, should be considered protected by the present patent.

Claims

A system (1) of drying materials (M) characterized by comprising:

at least a hydroextraction station (2) consisting of at least a hydroextraction device (3) provided with centrifugation means (4) of said materials (M);

at least a drying station (5) consisting of at least a drying device (6) and radiofrequency means (21) adapted to generate an electric field into which said materials (M) to be dried are immersed;

a plurality of material holders (8) in which said materials (M) to be dried are arranged;

and driving means (9) adapted to transfer said material holders with said materials (M) from said hydroextraction station (2) to said drying station (5).
The system (1) according to claim 1) characterized in that said drying station (5) comprises also suction means (11) connected to said material holders (8) arranged inside each corresponding drying device (6), said suction means (11) being adapted to carry out an active vacuum condition.
The system (1) according to claim 1) or 2) characterized by comprising at least a loading station of said materials (M) to be dried in said material holders (8) and at least an unloading station of said dried materials from said material holders (8).
The system (1) according to claim 3) characterized in that said driving means (9) carry out transfer of said material holders (8) from each loading station (10) to a corresponding hydroextraction station (2) and from each drying station (6) to a corresponding unloading station (10).
The system (1) according to claim 4) characterized in that said driving means (9) carry out also transfer of said material holders (8) from each hydroextraction station (2) to each drying station (5).
The system (1) according to claim 3) or 4) characterized in that each loading station (10) is coincident with a corresponding unloading station (10).
The system (1) according to claim 3) characterized in that each loading station is different from each unloading station.
The system (1) according to claim 1) characterized in that each hydroextraction device (3) comprises a container (12) to be closed by a lid (12a) internally provided with centrifugation means (4) of said material holders (8) and discharge ducts for the extracted water.
The system (1) according to claim 1) characterized in that each drying device (6) comprises a container (19) to be closed by a lid (19a), internally provided with armatures (20) generating an electric field and connected to a radiofrequency generator (21) and with rotation means (24) for said material holder (8).
The system (1) according to claim 9) characterized in that said rotation means (24) comprise a support plane (25) for said material holder (8) with said materials (M) to be dried, said support plane (25) being mechanically connected to driving means (26) adapted to put it into rotation around a vertical axis (Y) defined by a central core (22) rising from said support plane (25) and constituting one of said armatures (20) generating the electric field.
The system (1) according to claim 10) characterized in that said armatures (20) are made of conductive materials comprising:

a central core (22) with vertical development coaxially arranged inside said container (19);

one or more curved plates (23) with a concavity (23a) facing said central core (22) and arranged in proximity of parts of said container (19),

one of said armatures (20) being grounded and the other connected to said radiofrequency generator (21).
The system (1) according to claim 8) characterized in that said centrifugation means (4) comprise a basket (14) with perforated lateral surface (15) in which said material holder (8) with said materials (M) to be centrifuged is inserted, said basket (14) consisting of a bottom (16) mechanically connected to driving means (17) adapted to put it into rotation around a vertical axis (X) defined by a central core (18) rising from said bottom (16).
The system (1) according to claim 10) or 12) characterized in that said material holder (8) consists of a tubular body (28) adapted to be coaxially coupled outside said central core (22; 18), from which support arms (28) for said materials (M) to be dried are projecting.
The system (1) according to claim 13) characterized in that each of said support arms (29) comprises a first tubular member (30) peripherally fixed to said tubular body (28) and a second tubular member (31) telescopically and slidingly coupled to said first tubular member (30), said second tubular member (31) being provided with one or more swinging supports (32) adapted to receive said material (M) to be dried.
The system (1) according to claim 14) characterized in that said first tubular member (30) and said second tubular member (31) carry out a tight sealing coupling.
The system (1) according to claim 14) characterized in that said material (M) is yarn wound on a tube (T), said tube (T) being received on said swinging support (32).
The system (1) according to claim 16) characterized in that said swinging support (32) consists of a perforated support (33; 33a) receiving said tube (T) and provided with a base (36; 36a) freely coupled in a seat (34) made in said second tubular member (31).
The system (1) according to claim 17) characterized in that said swinging support (32) consists of a perforated conical support (33) receiving said tube (T) also having a conical shape.
The system (1) according to claim 17) characterized in that said swinging support (32) consist of perforated cylindrical support (33a) receiving said tube having a cylindrical shape as well.
The system (1) according to claim 17) characterized in that said seat (34) has a conical profile.
The system (1) according to claim 1) characterized in that said driving means (9) comprise at least a vertical column (35) to which a moving arm (36) provided with hooking means (37) for said material holder (8) is associated.
The system (1) according to claim 21) characterized in that said moving arm (36) is coupled to rotation means (38) adapted to put it into rotation around said vertical axis (Z) defined by said column (35).
The system (1) according to claim 21) characterized in that said moving arm (36) is also coupled to translation means (39) adapted to move it along said column (35).
The system (1) according to claim 2) characterized in that said suction means (11) consist of at least a vacuum pump (11 a).
The system (1) according to claim 3) characterized in that in each of said loading and unloading stations (10) rotation means (40) are arranged, adapted to support said material holder (8) and to put it into rotation around a vertical axis (K).
The system (1) according to claim 25) characterized in that said rotation means (40) comprise a support plane (41) adapted to support said material holder (8) and mechanically connected to driving means (42) adapted to put it into rotation around said vertical axis (K) defined by a central core (43) rising vertically from said support plane (41).