WO2024134698A1

WO2024134698A1 - Apparatus for the treatment of paper material

Info

Publication number: WO2024134698A1
Application number: PCT/IT2023/050291
Authority: WO
Inventors: Elena TROIA; Stefano Pecchia
Original assignee: Toscotec S.P.A.
Priority date: 2022-12-22
Filing date: 2023-12-20
Publication date: 2024-06-27
Also published as: IT202200026457A1

Abstract

Apparatus for the treatment of paper material of the type comprising: at least one drum (2) rotating at a pre-established speed around a respective rotation axis and provided with a perforated cylindrical surface with which a web of paper material (10) is placed in contact to be treated upstream of a Yankee cylinder; a channel (3) for conveying a flow of hot air towards the at least one drum (2) and the web of paper material which is temporarily in contact with it to transmit thermal energy to the at least one drum (2) and to the web of paper material by means of the flow of hot air; heating and ventilation means suitable for determining the formation of said flow of hot air; means for regulating the thermal energy conveyed along two or more terminal sections of the channel for conveying thehot air flow.

Description

TITLE

APPARATUS FOR THE TREATMENT OF PAPER MATERIAL

DESCRIPTION

The present invention relates to an apparatus for processing paper material. In particular, the subject of the invention is an apparatus for conditioning paper- fibrous material of the type called "TAD" which is used in the production of tissue paper in order to improve its softness and absorbency features.

The use of a technology which involves pressing the sheet when it is in a wet state to obtain relatively softtissue paper is known. This technology, which was the conventional process initially used, has been replaced by another type of process, called "Through-Air Drying" and known by the acronym "TAD"; the TAD process has become the standard technology for products positioned at the top end of the market thanks to their high absorbency and softness.

In this type of process, the web of paper material is dehydrated, minimizing the use of compressive means, thus avoiding the compaction that occurs during the wet pressing of the web in the conventional process.

TAD technology uses a jet of hot air blown through the tissue sheet before it reaches the Yankee cylinder. As regards the mechanical action on the sheet, this type of drying has a very slight impact, avoiding the strong action that would occur with a press if this has to provide the same contribution to dehydration when arranged in a non-TAD machineand resulting in products with greater bulk, softness and absorption capacity.

In its usual form, a TAD apparatus includes a drum formed by a cylindrical surface provided with radial openings and arranged in a chamber subjected to the action of a flow of hot air conveyed through a respective channel. The open area of the cylindrical surface of the drum is deliberately very large, as any obstacle to the flow of hot air must be minimised. The air is usually heated by gas heaters and the flow rate is adjustable by means of gate valves whose progressive closing determines a modulated reduction in the passage of air through the channel. The web of material to be treated that passes around the TAD drum before reaching the Yankee cylinder is subjected to the action of the hot air flow in order to determine its dehydration with limited mechanical deformation. A system for obtaining tissue paper can include also two or more TAD apparatuses arranged upstream of the Yankee cylinder. Furthermore, there are different possible configurations of the TAD section: a single large drum, a plurality of drums placed so asto form a sequential train in which the paper is always invested by the flow of air from a same direction, a plurality of smaller drums arranged so as to force the paper to follow a serpentine path so that the flow of hot air passes through the paper sequentially from two opposite directions.

In still other configurations the flow of hot air through the paper always occurs in correspondence with drums equipped with a cylindrical surface having a large part open for the air in which the flow of air itself reaches the drum perpendicular to the axis of rotation, crosses the paper supported by a structured cloth (that is, equipped with a three-dimensional structure to give thickness to the paper) and comes out of the drum itself not in a direction perpendicular to the axis, but, after a 90° change in direction, in a direction parallel to the axis of rotation, through special openings made on the drum heads.

One of the problems that can negatively influence known type TAD treatment apparatuses is related to the non-uniform ity in the flow of hot air that arrives on the drum and the consequent differentiation determined in the treatment undergone by the material. This phenomenon is particularly critical, as the nonuniformity of the dehydrating effect tends to increasingly get worse: where the drying paper has a higher degree of dryness, the permeability is higher; therefore, hot air tends to pass more easily through the less humid areas, increasing the dehydration of these areas and, therefore, further worsening the non-uniform ity of the sheet's humidity profile. The regulation of the dehydration capacity of the air flow along the width of the sheet therefore represents a very important objective, in order to improve the quality of the paper and the productivity of the machine. Existing TAD machines may have air flow regulation systems provided in the ducts upstream or downstream of the drum or of the drums used for drying the paper. These systems involve the division of the duct into discrete sectors by creating bulkheads along the width of the sheet. At each sector, a mobile damper implemented independently of the others allows the flow of hot air in that sector to be hindered, thus reducing the flow passing through the corresponding part of the sheet. This system allows only negative regulation to be carried out, in the sense that the pressure drop induced in the overall air flow increases as the need to correct the humidity profile of the sheet increases. In other words, each intervention to modify the flow occurs by locally reducing the air flow, with the effect of allowing a redistribution of the flows whose overall effect is, however, a reduction in the drying potential of the paper. This determines the fact that when there is a need for correction there is a reduction in the productivity of the machine.

TAD systems are described in LIS2019/0368812 and US4074441.

Among the objectives of the present invention is to eliminate the drawbacks of the known art by means of an apparatus for the treatment of paper material having the features indicated in claim 1 . Other innovative features are the subject of the dependent claims.

Among the advantages offered by the present invention it is possible to list the following: it is possible to determine a uniform drying in the transversal direction of the material that passes through the TAD apparatus, maximizing the drying performance of the TAD section and avoiding reducing the productivity of the system; it is possible to increase the adjustability of the humidity profile corrections along the width of the sheet, allowing to act on individual discrete air flows not only by reducing the flow, but also by increasing the air temperature and maintaining the same flow; it is possible to provide different levels of intervention by the flow of hot air on the material with respect to the direction followed by the material during its transit in multiple TAD apparatuses arranged in succession within a plant for the treatment of paper material; it is possible to provide different levels of intervention by the flow of hot air on the material with respect to a direction transverse to the direction followed by the material during its transit through the apparatus; the apparatus is provided with heating means which include one or more electric heaters which can advantageously be activated and also finely regulated according to the readings carried out by sensor means provided for this purpose on the apparatus; it increases the possibility of compensating for any non-uniform ities in the humidity profile of the sheet entering the TAD section, deriving from any anomalies or problems that may occur upstream of the TAD section itself.

These and further advantages and characteristics of the present invention will be more and better understood by every person skilled in the art thanks to the following description and the attached drawings, provided by way of example but not to be considered in a limiting sense, in which: - Fig. 1 is a diagram illustrating a first possible example of the implementation of an apparatus realized in accordance with the present invention;

- Figs. 2, 3 and 4 are three diagrams that illustrate a second, a third and a fourth possible example of embodiment of the invention in which several TAD drums are provided, arranged so as to act in succession along the direction followed by the paper material being treated;

- Figs. 5 and 6 are two diagrams that illustrate a fourth and fifth possible example of embodiment of the invention in which multiple channels are provided for conveying the hot air onto the TAD drum acting in axially differentiated sections of the same drum;

- Fig. 7 is a diagram relating to a possible arrangement of the operating areas in a tissue paper production plant.

With reference to the attached drawings, an apparatus (1 ) for the treatment of paper material made in accordance with the present invention is of the type which substantially includes at least one drum (2) around which the material being treated (10) passes and a channel (3) directed towards the drum (2) to convey a flow of hot air which invests the drum (2) and the web of paper material which is temporarily wrapped on the latter.

As shown schematically in Fig. 7, in a plant (100) for the production of tissue paper the TAD apparatus (1 ) is usually placed upstream of the Yankee cylinder and, as expressed previously, the same plant can be provided with two or more TAD apparatuses arranged in succession. The diagram in Fig. 7 shows the various operational zones of the system (100) following one another along the direction (MD) followed by the material being processed (10) starting from an initial formation zone (ZF) then passing through a drainage (ZD) to reach one or more TAD apparatuses (1 ) which are followed, downstream, by the Yankee cylinder located in the pressing area (ZP) and by a final packaging area (ZC).

The drum (2) is connected to corresponding moving means (not shown) which can move it in rotation (R2) around a respective longitudinal axis (x); in the examples illustrated in Figs. 1-3 the rotation movement is clockwise. Configurations may exist in which the TAD drums are placed to form a serpentine-shaped path for the material (10) being treated and in which the direction of rotation (R2) of the individual drums is alternated as in the example in Fig.4. The drum (2) has a cylindrical external surface characterized by a large open area, formed by radial openings distributed according to a known configuration, suitable for allowing the passage of the air flow used for the TAD process; the web of paper material to be treated (10) can be in direct contact with this surface while passing through the apparatus (1 ). The arrow (F) indicates the flow that invests the drum (2) while the arrows (V) schematically indicate the flow of air that, crossing the drum (2), passes through the web of material (10) being treated. Depending on the configuration used, the air flow can sequentially cross paper-structuredcloth-drum surface, or drum surface-paper-structured cloth. In such configurations the web of material (10) is supported by a structured cloth.

In the drawings the arrows (MD) indicate the direction of advancement of the web of material(IO); furthermore, the references (8) and (9) used in the drawings indicate two guiding rollers located respectively upstream and downstream of the TAD drum (2) along the path (MD) followed by the web (10). In the schematic example of Fig. 4, the references (8) and (9) indicate the guiding rollers located respectively upstream and downstream of the group of drums (2) which define the serpentine path followed by the web of material (10) inside the apparatus (1 ). Heating and ventilation means are provided on the channel (3) capable of determining a flow of hot air which invests the drum (2) and the web of paper material which is temporarily engaged thereon.

The ventilation means can be made up of any suitable means shaped and sized so as to produce a flow of air directed towards the drums (2) and can include, for example, fans, impellers, convectors, etc. In the drawings, the said ventilation means are schematically represented by a rectangle (MV) upstream of the arrow (F) which indicates the flow of hot air.

Advantageously, in accordance with the invention, the heating means include one or more electric heaters (4) which are represented schematically by means of a rounded rectangular figure provided in some of the attached drawings with two segments which can symbolically represent the relative connections.

The electric heaters (4) can include, for example, an electrical resistance of any type and geometry (cylindrical bars, plates, with smooth or finned surfaces, etc.) as well as other types of electric heating, for example by radiation (using infrared). Advantageously, the electric heaters (4) allow extremely precise and extensive adjustments. On the channel (3) through which the flow (F) passes, flow rate adjustment means (5) can be provided, which can be constituted, for example, by gate valves, rotary valves or other convenient means that can be activated and/or adjusted to vary the flow rate.

In the example of Fig. 2, three drums (2) are schematically shown positioned in succession along the direction (MD) of advancement of the web of material (10). Each of the drums (2) is invested by the flow conveyed by a corresponding channel (3A, 3B, 3C). In this embodiment a single electric heating element (4) is provided which is arranged in correspondence with a main section (30) of the channel (3) located upstream with respect to the channels (3A, 3B, 3C) which constitute three distinct terminal sections of the main channel (30); in practice, the channel (3) has a main section (30) which has three branches (3A, 3B, 3C) each of which constitutes a terminal section of the channel (3) and each of said terminal sections conveys a part of the flow ( F) to a respective drum (2), so that the thermal energy associated with the flow (F) can be distributed among the drums (2) of the apparatus (1 ); furthermore, flow regulation means (5) are provided which act in each of the channels (3A, 3B, 3C) in order to vary the flow (F) that reaches each drum (2).

Also in the example of Fig. 3 (in which the web 10 and other parts of the apparatus are not represented) three drums (2) placed in succession along the direction (MD) of advancement of the web of material (10) are schematically shown. In this embodiment of the invention each of the drums (2) is invested by the air flow conveyed by a corresponding channel (3A, 3B, 3C); in this embodiment the electric heaters (4) are arranged in correspondence with each of the three channels (3A, 3B, 3C). Furthermore, in each of the three channels (3A, 3B, 3C) a gate valve flow regulation device (5) is arranged and acting.

In the example of Fig. 4, as expressed previously, three drums (2) are schematically shown placed in succession and staggered at different heights along the direction (MD) of advancement of the web (10) so as to define a serpentine path. In practice, the web (10) reaches the apparatus (1 ) from the left, passing through the guiding roller (8) located upstream along the path of the web (10) and comes into contact with the first drum (2) arranged left in the drawing. Subsequently the web (10) passes around the second drum (2) which rotates in the opposite direction in relation to the first (the first clockwise and the second anti-clockwise in the example) to then reach the third drum (2) located downstream, immediately upstream of the guiding roller (9) located downstream along said path. The third drum (2) rotates in the same direction as the first. In this embodiment of the invention each of the drums (2) is invested by a corresponding channel (3); in this embodiment the electric heaters (4) are arranged in correspondence with each of the three channels (3A, 3B, 3C). Furthermore, in each of the three channels (3A, 3B, 3C) a respective gate valve (5) is arranged and acting. Also in this example, the reference (30) indicates the main section of the channel (3) through which the flow (F) is conveyed and branches towards each drum (2) crossing the channels (3A, 3B, 3C).

In the examples of Figs.2-4 the channels (3A, 3B, 3C) are aligned along the direction (MD).

In the example shown in Fig. 5, the channel (3) that conveys the flow (F) to the drum (2) has three terminal sections (3A, 3B, 3C) aligned along the axial development of the drum (2). The reference numeral (X) denotes the axis of the drum (2) and the reference (CD) denotes the so-called "cross direction", i.e. the direction transverse to the direction of advancement (MD) of the web being treated. The web of material being treated (10) is only partially shown in the upper part of the drum (2). In this example the apparatus (1 ) includes one or more electric heaters (4) for each of the terminal sections (3A, 3B, 3C) of the channel (3). Furthermore, in each of the terminal sections (3A, 3B, 3C) flow regulation means (5) acting on the individual section are provided. In practice, the web of material (10) passing over the drum (2) can be heated, along its width (direction CD), by flows of different flow rate and/or temperature depending on the corresponding terminal section (3A, 3B, 3C) from which the flow of hot air (F) arrives. The number of zones in the CD direction affected by independent flow control via flow regulators and independent temperature control via electric heaters may vary: the maximum number of zones that can be controlled in flow and temperature depends solely on the size of the regulation systems and on the level of complexity deemed economically acceptable.

Fig. 6 schematically shows an example of embodiment in which the channel (3) which conveys the flow (F) to the drum (2) has three end sections (3A, 3B, 3C) aligned along the axial development of said drum (2) in the area closest to the drum (2), while in the area furthest from the same drum (2), i.e. further upstream with respect to the flow direction (F), there is a main section (30) where a single element electric heater (4) is placed. In each of the three sections (3A, 3B, 3C) flow regulation means (5) are provided which allow the flows in the individual sections to be varied. In Fig.6 the web of material (10) being processed has not been represented.

The drum (2) can be provided along its axial development with one or more radial walls (20) suitable for dividing the drum (2) into corresponding cylindrical sections (2A, 2B, 2C) arranged in correspondence with each of said two or more terminal sections (3A, 3B, 3C) so as to be affected independently by the relative flows passing through the sections themselves. The walls (20) are represented by a discontinuous line in Figs. 5 and 6.

As will also be described later, the two types of differentiation of temperature regulation and/or flow rate, i.e. differentiation along the material treatment direction (MD) and along the transverse direction (CD), can also be used in combination, by combining the regulation on several different terminal sections (3A, 3B, 3C) of the channel (3).

Fig.1 schematically represents with the block (UC) a central processing unit that equips the apparatus (1 ), while two trapezoidal figures (6) represent sensor means (6) suitable for detecting at least the humidity parameters present in the material being treated. The sensor means can include a scanner device, known per se, suitable for detecting the degree of humidity presented by the web of material (10) being treated along its width, i.e. along a transverse portion thereof so as to detect any non-uniform ities. The central unit (UC) and its connections have not been represented in all drawings.

At least one sensor (6) for measuring the moisture content in the transverse direction (CD) of the dried sheet is normally placed downstream of the drying zone and immediately upstream of the packaging zone (ZC). The positioning of the sensors (6) may vary depending on the type of detection to be performed. For example, the sensors (6) can also be arranged upstream and downstream of each drum (2) to check the degree of dehydration of the material (10) being treated, obtaining corresponding values that correlate a given portion of the web (10) to the position which this portion temporarily has inside the TAD apparatus (1 ). The sensors can also be arranged and act in other areas of the system to allow regulation of the heating means (4) and/or of the flow regulation means (5) which takes into account parameters also detected in other areas of the plant.

The central unit (UC) is connected to the sensor means (6), to said one or more electric heaters (4) and/or to said flow regulation means (5) so as to vary the temperature and/or flow rate of the flow (F) based on the values detected by the sensor means (6). The same central unit (UC) can be provided with a database including reference values and software capable of allowing both activation and regulation of the electric heaters (4), and of the gate valves (5) on the basis of predefined activation and regulation criteria.

In the example of Fig.1 the sensor means (6) are arranged upstream and downstream of the TAD apparatus (1 ). The flow regulation (F) can also take place using sensors located in other areas of the plant (100).

In practice, it is possible to state that with the present invention the treatment performed by the TAD apparatus is optimized thanks to the possibility of varying the temperature and flow rate of the air flow (F) in a broad and precise way because it is possible to intervene both on the electric heaters (4) and on the gate valves (5), with differentiation both in the direction of advancement (MD) of the web to be treated (10) and in the transversal direction (CD).

Therefore, based on the readings carried out by the sensors (6), the central unit (UC) will consequently drive the heaters (4) and the flow regulation means (5). For example, using the reference of Fig.5, in the event of detection by the sensors (6) (not represented in Fig.5) of a humidity value that is too high in the portion of the web (10) corresponding to the area on the right in the drawing, the central unit (UC) will increase the temperature of the heating means (4) located on the right and/or the opening of the gate valve located in the section (3C) located on the right. This differentiation in the treatment between the various areas of the web (10) can be carried out on a single TAD drum (2) or on multiple TAD drums (2) in succession, with interventions that can be differentiated from each other based on the values detected from the sensors (6).

In other words, the regulation of the input of thermal energy that the flow (F) determines on the web of material (10) being treated can vary according to a plurality of parameters that can be combined with each other: possible regulation of the temperature of flow temperature (F), regulation of the temperature of the electric heaters (4) along the machine direction (MD), regulation of the opening of the gate valves (5) along the machine direction (MD), regulation of the temperature of the electric heaters (4) along the transversal direction (CD), adjustment of the opening of the gate valves (5) along the transversal direction (CD).

All adjustments can be managed using the readings of the sensors (6) which will be compared with a series of data stored in a database associated with the central unit (UC).

The aforementioned adjustments can be made automatically by the central unit (UC) or semi-automatically/manually by operators based on the data detected by the sensors (6).

For example, commercially available microwave scanners can be used as sensors, which exploit the ability of the water contained in the sheet to absorb radiation with a wavelength typical of the microwave field. By emitting microwaves and measuring the microwaves that pass through the sheet, it is possible to trace the energy absorbed by the sheet, which is greater the higher the degree of humidity. Indirectly, this measurement allows the moisture content to be measured with great speed and good precision.

The sensors (6) can, in some cases, be associated with weight meters based on the absorption of beta particles emitted by radioactive sources. Contextual knowledge of moisture content and weight improves measurement accuracy.

By way of example, batteries of electrical resistances can be used as heaters which have a specific power density (power per unit of sheet width) between 100W/mm and 1000W/mm, preferably between 250W/mm and 750W/mm, in order to have a sufficient power density to allow the regulation of the flow temperature. Heaters based on the use of electrical resistors and intended for heating air flows and which could be used for the implementation of the present invention are present on the market in the form of metal “U”-shaped tubes and of various lengths with internal resistors, the ends of which are connected to the upper part which has the electrical contacts. These heating “U-elements" can be assembled to form a matrix of electrical resistors (up to many tens) to be embedded in the duct where the air to be heated is made to flow: in this way it is possible to obtain an exchange surface sufficient for operation of the system.

Other systems may include the insertion of heating elements inside finned structures, in order to further increase the heat exchange surfaces.

It is apparent from the foregoing description that an apparatus for processing paper material in accordance with the present invention comprises:

- at least one drum (2) rotating at a pre-established speed around a respective rotation axis and provided with a perforated cylindrical surface with which a web of paper material (10) to be treated upstream of a Yankee cylinder is placed in contact;

- a channel (3) for conveying a flow of hot air towards the at least one drum (2) and the web of paper material which is temporarily in contact with it to transmit thermal energy to the at least one drum (2) and to the web of paper material by the flow of hot air;

- heating and ventilation means suitable for determining the formation of said flow of hot air;

- apparatus (1 ) wherein said heating means comprise one or more electric heaters (4), wherein said conveying channel (3) comprises two or more terminal sections (3A, 3B, 3C) facing the at least one drum (2) each of which conveys a respective part of the said flow of hot air towards the at least one drum (2) so as to convey towards the at least one drum (2) a corresponding part of the said thermal energy, wherein each of the said end sections is provided with means for regulating the thermal energy conveyed by it and wherein said means for regulating the thermal energy conveyed by each of said terminal sections are means for regulating the thermal power emitted by each electric heater (4) and/or means to regulate the flow of hot air conveyed by each of said terminal sections.

It is also apparent from the foregoing description that an apparatus in accordance with the present invention may also comprise one or more of the following features also combined with each other:

- said one or more electric heaters (4) are arranged at each of said terminal sections (3A, 3B, 3C).

- said one or more electric heaters (4) are arranged in correspondence with a main channel (30) located upstream with respect to each of said terminal sections (3A, 3B, 3C) and in which flow regulation means (5) are provided, acting in each of said terminal sections (3A, 3B, 3C).

- said terminal sections (3A, 3B, 3C) are arranged along the axial development of said at least one drum (2).

- said terminal sections (3A, 3B, 3C) are arranged along the axial development of said at least one drum (2) and said one or more electric heaters (4) are arranged upstream with respect to each of said terminal sections (3A, 3B, 3C), flow regulation means (5) being provided acting in each of said two or more sections (3A, 3B, 3C).

- said terminal sections (3A, 3B, 3C) are arranged along the axial development of said at least one drum (2), wherein at least one electric heater (4) is arranged in each section (3A, 3B, 3C) and wherein each section (3A, 3B, 3C) includes flow regulation means.

- said at least one drum (2) is provided along its axial development with one or more radial walls (20) adapted for dividing the drum (2) into corresponding cylindrical sections (2a, 2B, 2C) arranged in correspondence with each of said two or more sections (3A, 3B, 3C) so as to be affected independently by the respective flows passing through the sections themselves.

- it is provided a central processing unit (UC) and sensor means (6) suitable for detecting at least the humidity parameters present in the material being treated by the apparatus (1 ) and said central unit (UC) is connected to said sensor means (6), to said one or more electric heaters (4) and/or to said flow regulation means (5) so as to vary the temperature and/or flow rate (F) according to the values detected by said sensor means (6).

- said sensor means (6) are arranged upstream and/or downstream of said apparatus (1 ) with respect to the direction (MD) followed by the material (10).

- the perforated cylindrical surface of said at least one drum (2) is formed by an open area defining at least 70% of the same cylindrical surface.

The execution details may however vary in an equivalent manner in the shape, dimensions, arrangement of the elements, nature of the materials used, without however departing from the scope of the idea of the solution adopted or of the inventive concept and therefore remaining within the limits of the protection granted by this patent.

Claims

1. Apparatus for the treatment of paper material of the type comprising:

- a channel (3) for conveying a flow of hot air towards the at least one drum (2) and the web of paper material which is temporarily in contact with it to transmit thermal energy to the at least one drum (2) and to the web of paper material by the flow of hot air; and

- heating and ventilation means suitable for determining the formation of said flow of hot air; wherein said heating means comprise one or more electric heaters (4), wherein said conveying channel (3) comprises two or more terminal sections (3A, 3B, 3C) facing the at least one drum (2) each of which conveys a respective part of the said flow of hot air towards the at least one drum (2) so as to convey towards the at least one drum (2) a corresponding share of the said thermal energy, wherein each of the said end sections is provided with means for regulating the thermal energy conveyed by it and wherein said means for regulating the thermal energy conveyed by each of said terminal sections are means for regulating the thermal power emitted by each electric heater (4) and/or means to regulate the flow of hot air conveyed by each of said terminal sections.

2. Apparatus (1 ) according to claim 1 , wherein said one or more electric heaters (4) are arranged at each of said terminal sections (3A, 3B, 3C).

3. Apparatus (1 ) according to claim 1 , wherein said one or more electric heaters (4) are arranged in correspondence with a main channel (30) located upstream with respect to each of said terminal sections (3A, 3B, 3C) and wherein flow regulation means (5) are provided, acting in each of said terminal sections (3A, 3B, 3C).

4. Apparatus (1 ) according to one of the previous claims, wherein said terminal sections (3A, 3B, 3C) are arranged along the axial development of said at least one drum (2).

5. Apparatus (1 ) according to one of the previous claims, wherein said terminal sections (3A, 3B, 3C) are arranged along the axial development of said at least one drum (2) and wherein said one or more electric heaters (4 ) are arranged upstream with respect to each of said terminal sections (3A, 3B, 3C), flow regulation means (5) being provided acting in each of said two or more sections (3A, 3B, 3C).

6. Apparatus (1 ) according to one of claims 1 to 4, wherein said terminal sections (3A, 3B, 3C) are arranged along the axial development of said at least one drum (2), wherein at least one electric heater (4) is arranged in each section (3A, 3B, 3C) and wherein each section (3A, 3B, 3C) includes flow regulation means.

7. Apparatus (1 ) according to claims 4 to 6, characterized in that said at least one drum (2) is provided along its axial development with one or more radial walls (20) suitable for dividing the drum (2) into corresponding cylindrical sections (2a, 2B, 2C) arranged in correspondence with each of said two or more sections (3A, 3B, 3C) so as to be affected independently by the respective flows passing through the sections themselves.

8. Apparatus (1 ) according to one of the previous claims, characterized in that it is provided with a central processing unit (UC) and sensor means (6) suitable for detecting at least the humidity parameters present in the material being treated by the apparatus (1 ) and in that said central unit (UC) is connected to said sensor means (6), to said one or more electric heaters (4) and/or to said flow regulation means (5) so as to vary the temperature and/or flow rate (F) according to the values detected by said sensor means (6).

9. Apparatus (1 ) according to claim 7, characterized in that said sensor means (6) are arranged upstream and/or downstream of said apparatus (1 ) with respect to the direction (MD) followed by the material (10).

10. Apparatus (1 ) according to one of the previous claims, characterized in that the perforated cylindrical surface of said at least one drum (2) is formed by an open area defining at least 70% of the same cylindrical surface.