Method and plant for the production of a web based on material of plant origin.

Abstract

A method for the production of a web (N) based on material of plant origin, comprises a step of making a mixture based on material of plant origin, comprising at least one dry component and at least one moist component, followed by a step of laminating the mixture to obtain a continuous layer (S) of material, and then by a step of drying the layer (S) of material to obtain a web (N) having a predetermined moisture content. The step of drying the layer (S) of material is carried out at a temperature of between 70°C and 150°C.

Description

[0001] DESCRIPTION

[0002] METHOD AND PLANT FOR THE PRODUCTION OF A WEB BASED ON MATERIAL OF PLANT ORIGIN

[0003] Technical field

[0004] This invention relates to a method and a plant for the production of a web which is based on material of plant origin and intended, in particular, for the smoking article industry.

[0005] Background art

[0006] In the prior art of the sector relevant to this invention, webs of this kind are made by mixing and processing at least one dry, plant component, such as, for example, tobacco and / or a non-tobacco material (rapeseed, straw or other plant varieties, cellulose or cellulose derivates) and a moist component, such as water and other additives, for example.

[0007] The dry component and the moist component are mixed together to obtain the mixture which is then spread evenly in the form of a layer on a conveyor which takes it to a drying station, where its moisture content is reduced until it reaches a predetermined percentage content. Depending on the type of mixture and on the percentage of moisture it contains, the layer of material may be formed according to different processes.

[0008] In a first example, mixtures classified as "slurry", which have a high percentage content of moisture (greater than 60%), are typically formed into an even layer of material using a "casting" process.

[0009] In a second example, mixtures classified as "dough", which have a reduced percentage content of moisture (between 10% and 65%), are typically formed into an even layer of material using a laminating process. Whatever the type of mixture and the process used to form it, the layer of material is then dried in order to reduce its content of moisture and solvents so as to obtain a layer of material having predetermined mechanical properties. In the prior art of the sector relevant to this invention, drying is carried out at a temperature greater than 150°C.

[0010] The Applicant has noticed that this technology, though effective when applied to layers of material obtained from slurry type mixtures, has some disadvantages if applied to layers of material obtained from dough type mixtures and can be improved.

[0011] Firstly, excessively high temperatures can negatively influence the chemical properties of the mixture, particularly its organoleptic properties, thus reducing the overall quality of the end product.

[0012] Secondly, a high drying temperature may lead to a rapid loss of moisture, making the layer of material too dry and thus negatively affecting its mechanical properties, for example, its flexibility.

[0013] Moreover, excessively high temperatures may contribute to the formation of harmful or undesirable substances in the layer of material, making the end product less healthy.

[0014] Lastly, higher temperatures require more energy for the drying process. This may translate as higher operating costs linked to energy.

[0015] The technical purpose of this invention is, therefore, to provide a method and a plant for the production of a web based on material of plant origin to overcome the above mentioned disadvantages of the prior art.

[0016] Aim of the invention

[0017] The principal aim of this invention is, therefore, to provide a method and a plant for the production of a web based on material of plant origin and able to guarantee that the end product is of high quality.

[0018] A further aim of this invention is to provide a method and a plant for the production of a web based on material of plant origin and capable of optimizing the energy expenditure of the plant.

[0019] The technical purpose and aims specified are substantially achieved by a method and a plant for the production of a web based on material of plant origin comprising the technical features set out in the appended claims 1 and 11 , respectively, and / or in one or more of the claims dependent thereon and / or in the accompanying description.

[0020] In particular, the Applicant has found that the use of a temperature between 70°C and 150°C to dry a layer of material obtained by lamination ensures optimum drying of the layer of material and at the same time ensures that the physical and organoleptic properties of the material are not lost.

[0021] The Applicant has also found that using a drying station comprising at least one hot air flow generator provided with at least a first fan and a second fan, which are disposed to direct the hot air flow towards opposite sides of the continuous layer, in particular above the support and below the support, allows the continuous layer to be dried in a uniform and efficient manner. This aspect has advantages which are independent of the temperatures used for the drying process and thus constitutes an aspect which is protectable separately from the inventive aspect linked to the drying temperatures.

[0022] Preferably, the first fan and the second fan are operable at different rotational frequencies. The first fan is operable at a lower rotational frequency compared to the second fan. Advantageously, this asymmetrical configuration is designed to maximize the efficiency of the process, ensuring that drying is carried out uniformly and thoroughly, thus contributing to ensuring the optimum quality of the end product.

[0023] Brief description of the drawings

[0024] Further features and advantages of this invention are more apparent in the exemplary, hence non-limiting description of a preferred, but nonexclusive, embodiment of a method and a plant for the production of a web based on material of plant origin according to the invention.

[0025] The description is set out below with reference to the accompanying drawings which are provided solely for purposes of illustration without limiting the scope of the invention, and where Figure 1 shows a schematic view of a preferred, example embodiment of a plant 1 according to this invention, for the production of a web N based on material of plant origin.

[0026] Detailed description of preferred embodiments of the invention

[0027] Accordingly, an embodiment of the method for the production of a web based on material of plant origin will now be described with reference to the plant 1 used to implement the method.

[0028] In this description, the expression "material of plant origin" is used to mean a plant-based material (tobacco or non-tobacco) processed by grinding or similar process to modify its particle size in order to facilitate its subsequent mixing treatments. In particular, it is used to mean that the continuous web is a semifinished product obtained by mixing and processing at least one dry, plant component, such as, for example, tobacco and / or a non-tobacco material (rapeseed, hemp, straw or other plant varieties, cellulose or cellulose derivates, aromatic leaves and so on) and a moist component, such as water and one or more additives, in accordance with the general nature of the invention.

[0029] As shown in Figure 1 , the plant 1 comprises a kneader 2 configured to mix together at least one dry component and at least one moist component. The components are selected according to the specific requirements of the application or of the product to be made.

[0030] The mixture thus obtained preferably has a moisture content (by weight) of between 10% and 65%, preferably between 20% and 55% by weight. The mixture can be considered to be a dough-type mixture, that is to say, a mixture having a pasty or viscous consistency, more specifically making it malleable. In other words, the mixture has a liquid content that is lower than that of a slurry but nevertheless such as to make the mixture compact enough to make it suitable for subsequent processes that give it its shape. The kneader 2 has a structure of known type. For example, the kneader 2 may be configured to deliver discontinuous quantities of mixture, each deriving from a cycle of loading the components and mixing them together. Alternatively, the kneader 2 may be configured to deliver a continuous quantity of mixture, derived from a continuous process of continuously loading the components and mixing them together.

[0031] Next, the mixture is moved along a feed path and laminated to obtain a continuous layer S. For this purpose, the plant 1 comprises a laminating unit 3 for forming the continuous layer S from the mixture.

[0032] The laminating unit 3 has a structure of known type. For example, the laminating unit 3 may comprise a plurality of laminating stages 3a, 3b disposed in succession along the feed path of the continuous layer S and configured to first of all form the continuous layer S and then gradually reduce the thickness of the continuous layer S. Each laminating stage 3a, 3b comprises a respective pair of opposing rollers.

[0033] Depending on the specific requirements of the application or of the product to be made, the laminating stages 3a, 3b may be configured to perform a vertical lamination and / or a horizontal lamination of the product.

[0034] Whatever the type of lamination used, the continuous layer S is then released onto a support 4, preferably a conveyor, configured to convey the continuous layer S along the feed path to the processing units downstream.

[0035] Preferably, the conveyor is a conveyor belt and is configured to support the continuous layer S from below and to move it along the feed direction.

[0036] Preferably, the continuous layer S disposed on the support 4 has a substantially uniform thickness. Preferably, the continuous layer S disposed on the support 4 has a thickness of between 0.15 mm and 1 mm, and more preferably, between 0.2 and 0.25 mm.

[0037] As shown in Figure 1 , downstream of the laminating unit 3, the plant 1 comprises a drying station 5 configured for receiving the continuous layer S from the support 4 and for drying the continuous layer S to obtain a web N of material having a predetermined moisture content. Preferably, after the drying process, the web N of material has a moisture content of between 4% and 30% by weight. Still more preferably, the web N of material has a moisture content of between 6% and 20% by weight.

[0038] According to an aspect peculiar to the invention, the step of drying the continuous layer S is carried out at a temperature of between 70°C and 150°C.

[0039] In an example, in which the dry, plant component is at least partly tobacco, the drying temperature is between 70°C and 140°C.

[0040] In a different example, in which the dry, plant component is at least partly non-tobacco material, such as cellulose, for example, the drying temperature is between 70°C and 150°C.

[0041] Advantageously, this technical feature allows optimum drying of the continuous layer S, preserving its physical and organoleptic properties and, at the same time, offers a balanced compromise for the plant 1 , especially in balancing the energy efficiency and the dwell time of the continuous layer S inside the drying station 5.

[0042] In particular, this temperature range allows obtaining a web N of material which is uniformly and efficiently dried so as to make the web N of material suitable for the subsequent stages of the process, preventing the web N from deteriorating and from becoming mouldy and allowing the organoleptic properties of the web N of material to be kept substantially unchanged.

[0043] According to a preferred aspect, the continuous layer S is dried in two or more drying sub-steps, which are carried out in succession, preferably in direct succession, along the feed path of the continuous layer S and, preferably, at respective temperature ranges. Preferably, the two or more sub-steps are carried out at decreasing temperature ranges.

[0044] By "direct succession" is meant a sequence without intermediate steps of processing the mixture forming the continuous layer S (for example, without mixing in any additives).

[0045] In a particularly advantageous embodiment of the method, the continuous layer S is subjected to a primary step of drying which is carried out at a temperature of between 95°C and 150°C, followed by a secondary step of drying which is carried out at a temperature of between 70°C and 120°C.

[0046] In an example, in which the dry, plant component is at least partly tobacco, the primary step of drying is carried out at a temperature of between 95°C and 140°C, while the secondary step of drying is carried out at a temperature of between 70° and 120°C.

[0047] In a different example, in which the dry, plant component is at least partly non-tobacco material, such as cellulose, for example, the primary step of drying is carried out at a temperature of between 95°C and 150°C, while the secondary step of drying is carried out at a temperature of between 70° and 120°C.

[0048] Preferably, following the primary step of drying, the continuous layer S has a moisture content of between 19% and 28% by weight, preferably between 20% and 25% by weight. Preferably, following the secondary step of drying, the continuous layer S has a moisture content of between 4% and 30% by weight, preferably between 6% and 20% by weight.

[0049] For this purpose, the plant 1 comprises a primary drying station 5a for drying the continuous layer S at a temperature of between 95°C and 150°C, and, downstream of it, a secondary drying station 5b for drying the continuous layer S at a temperature of between 70°C and 120°C.

[0050] At a functional level, the primary step of drying dries the mixture quickly and effectively, allowing the initial moisture content to be efficiently removed. This is crucial to prevent the formation of bubbles or flaws in the structure of the material during the subsequent steps. Furthermore, the higher temperatures during the primary step of drying can contribute to stabilizing and fixing the shape of the material, creating a solid base for subsequent handling. The secondary step of drying, on the other hand, allows the material to be dried in a slower and more controlled manner so it reaches the optimum level of moisture, neither too wet nor too dry. This gradual process helps to preserve the desired organoleptic properties, such as flavour and aroma, ensuring the final quality of the product. Advantageously, in other words, the use of two successive steps of drying makes it possible to obtain a final product of top quality, with optimum consistency and well-preserved organoleptic properties.

[0051] According to a preferable aspect, during the step of drying the continuous layer S, a flow of hot air is delivered to the continuous layer S. In other words, hot air flows into contact with the continuous layer S. For this purpose, the drying station 5 comprises at least one hot air flow generator 6.

[0052] Preferably, the flow of hot air is conveyed by a plurality of fans 7a, 7b disposed and / or configured to convey the flow of hot air towards opposite sides of the continuous layer S. Preferably, the hot air flow generator 6 comprises at least one first fan 7a located above the support and at least one second fan 7b located under the support. Structurally, the first fan 7a and the second fan 7b each comprise at least one blade which is rotatable about a respective axis.

[0053] Functionally, during the step of drying, the continuous layer S is disposed on the support while the at least one first fan 7a conveys a hot air flow above the support 4 and the at least one second fan 7b conveys a hot air flow under the support 4.

[0054] According to a preferable aspect, the first fan 7a and the second fan 7b are operable at different rotational frequencies. Preferably, the first fan 7a is operable at a lower rotational frequency compared to the second fan 7b. For this purpose, the plant 1 further comprises a control and drive unit U, configured to drive the first fan and the second fan at different rotational frequencies. Preferably, the control and drive unit U is configured to drive the first fan at a lower rotational frequency compared to the second fan.

[0055] Advantageously, this asymmetrical configuration is designed to maximize the efficiency of the process, ensuring that drying is carried out uniformly and thoroughly, thus contributing to ensuring the optimum quality of the end product. According to a preferable aspect, during the step of drying, at least one operating parameter is detected and the temperature of the step of drying the continuous layer is regulated on the basis of the parameter detected. Preferably, one of the following parameters is detected: moisture content of the mixture and / or of the continuous layer S, thickness of the continuous layer S, density of the mixture and / or of the continuous layer S .

[0056] For this purpose, the plant 1 comprises at least one sensor, connected to the aforesaid control and drive unit U and configured to detect at least one of the aforesaid parameters and to generate a corresponding signal to be sent to the control and drive unit U. The control and drive unit U is configured to receive the signal emitted by the sensor and to adjust the drying station 5 based on the parameter detected.

[0057] Advantageously, this technical feature ensures an optimum drying environment. This not only reduces the risk of underprocessing or overheating, but also allows adapting production to the specific requirements of the material, improving overall process efficiency and increasing operating flexibility.

[0058] The present invention achieves the preset aims, overcoming the disadvantages of the prior art.

[0059] In effect, the method and plant 1 of the invention make it possible to obtain a web N of material having optimized physical and organoleptic properties and, at the same time, allow rationalizing energy expenditure and plant efficiency.

Claims

CLAIMS1 . A method for the production of a web based on material of plant origin, comprising the following steps: making a mixture based on material of plant origin, the mixture comprising at least one dry component and at least one moist component; laminating the mixture to obtain a continuous layer (S); drying the layer (S) of material to obtain a web (N) having a predetermined moisture content; characterized in that: the step of drying the continuous layer (S) is carried out at a temperature of between 70°C and 150°C.

2. The method according to claim 1 , wherein the mixture has a moisture content of between 10% and 65% by weight, preferably between 20% and 55% by weight.

3. The method according to claim 1 or 2, wherein the continuous layer (S), after the step of drying, has a moisture content of between 4% and 30% by weight, preferably between 6% and 20% by weight.

4. The method according to any one of the preceding claims, wherein the step of drying the continuous layer (S) comprises a primary step of drying carried out at a temperature of between 95°C and 150°C and a secondary step of drying carried out at a temperature of between 70°C and 120°C, the primary step and the secondary step being preferably carried out directly one after the other.

5. The method according to claim 4, wherein, after the primary step of drying, the continuous layer (S) has a moisture content of between 19% and 28% by weight, preferably between 20% and 25% by weight.

6. The method according to any one of the preceding claims, comprising the further steps of: detecting at least one of the following parameters: moisture content of the mixture and / or of the layer (S) of material, thickness of the continuous layer (S), density of the mixture and / or of the continuous layer(S); adjusting the temperature of the step of drying based on the parameter detected.

7. The method according to any one of the preceding claims, wherein the step of drying comprises a step of delivering a flow of hot air to the layer of material.

8. The method according to claim 8, wherein the step of delivering a flow of hot air to the continuous layer (S) comprises the step of conveying the flow of hot air towards the continuous layer (S) via at least a first fan (7a) and a second fan (7b), the fans being disposed to convey the flow of hot air towards opposite sides of the continuous layer (S).

9. The method according to claim 8, wherein, during the step of drying, the continuous layer (S) is positioned on a support (4); and wherein the first fan (7a) is located above the support (4) and the second fan (7b) is located under the support.

10. The method according to claim 8 or 9, wherein the first fan (7a) and the second fan (7b) are operable at different rotational frequencies, in particular so that the first fan (7a) is operable at a lower rotational frequency compared to the second fan (7b).

11. A plant (1 ) for the production of a web (N) based on material of plant origin, comprising: a kneader (2) for mixing together at least one dry component and at least one moist component to form a mixture preferably having a moisture content of between 10% and 65% by weight; a laminating unit (3) for forming a continuous layer (S) from the mixture; a support (4), preferably a conveyor, for receiving the continuous layer (S); a drying station (5) for receiving the continuous layer (S) from the support (4) and for drying the continuous layer (S) to obtain a web (N) of material having a predetermined moisture content;characterized in that the drying station (5) being configured to dry the layer (S) of material at a temperature of between 70°C and 150°C.

12. The plant (1 ) according to claim 11 , wherein the drying station (5) comprises a primary drying station (5a) for drying the continuous layer (S) at a temperature of between 95°C and 150°C, and a secondary drying station (5b) for drying the continuous layer (S) at a temperature of between 70°C and 120°C, the primary drying station (5a) and the secondary drying station (5b) being preferably located directly one after the other.

13. The plant (1 ) according to claim 12, wherein the primary drying station (5a) is configured to dry the continuous layer (S), to obtain a moisture content of between 19% and 28% by weight, preferably between 20% and 25% by weight.

14. The plant (1 ) according to claim 12 or 13, wherein the secondary drying station (5b) is configured to dry the continuous layer (S), to obtain a moisture content of between 4% and 30% by weight, preferably between 6% and 20% by weight.

15. The plant (1 ) according to any one of claims 11 to 13, comprising at least one sensor for detecting at least one of the following parameters: moisture content of the mixture and / or of the continuous layer (S), thickness of the continuous layer (S), density of the mixture and / or of the continuous layer (S), and generating a corresponding signal; and further comprising a control and drive unit (U), connected to the sensor and to the drying station (5), for receiving the signal emitted by the sensor and adjusting the drying station (5) based on the parameter detected.

16. The plant (1 ) according to any one of claims 11 to 13, wherein the drying station (5) comprises at least one hot air flow generator (6).

17. The plant (1 ) according to claim 16, wherein the hot air flow generator (6) comprises at least a first fan (7a) and a second fan (7b), said fans (7a, 7b) being disposed to convey the flow of hot air towards opposite sides of the continuous layer (S), in particular being disposed above the support (4) and under the support (4).

18. The plant (1 ) according to claim 17, further comprising a control and drive unit (U), configured to drive the first fan (7a) and the second fan (7b) at different rotational frequencies, in particular to drive the first fan (7a) at a lower rotational frequency compared to the second fan (7b).

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