KR20220156036A - Method for producing a homogeneous sheet of nicotine-free vegetable fiber - Google Patents

Abstract

A process for preparing a homogeneous sheet of nicotine-free vegetable fibers characterized by the fact that:
- crushing the solid component of the raw material containing nicotine-free vegetable fiber to a particle size of about 20 to 220 μm, preferably about 80 to 180 μm,
- mixing the ground material thus obtained with water, one or more binders and one or more substances forming an aerosol, until a mixture is obtained with a liquid content of about 30-50%, preferably about 35-40%,
- the mixture is applied in a first lamination to obtain a continuous strip having a thickness of about 1-20 mm, preferably about 1-10 mm,
- the strip already provided with the first lamination is subjected to a series of further lamination steps until a strip having a very constant thickness of about 90 to 280 μm, preferably about 140 to 200 μm is obtained;
- The strip is dried until it retains about 8-15% liquid.

Description

Method for producing a homogeneous sheet of nicotine-free vegetable fiber

The present invention relates to a method for preparing homogeneous sheets of nicotine-free vegetable fibers.

Methods for producing reconstituted tobacco sheets are known, both conventional and unusual, the unusual being also referred to as HNB (Heat Not Burn). Reconstituted tobacco is generally obtained by using tobacco by-products and processed scraps (ribs, leaf scraps, powders, etc.), which are properly ground into a substantially powder, water, glycerin binder and other liquid additives are about 70% liquid by weight. It is possible to obtain a very fluid mixture (slurry) with a high content, which is then poured into a steel strip in the form of a veil and transferred to a drying step. Here the liquid part of the mixture evaporates, and the solid residue forms a kind of continuous tobacco strip having a width approximately equal to that of the steel strip. The dried mixture strip is then separated from the steel strip and cut into pieces of various sizes as required. The pieces are then transformed into thin filaments, properly mixed, and fed into existing cigarette packaging machines.

Depending on the raw material used, in particular whether shredded tobacco by-products with a particle size between 20 μm and 220 μm are used, or whether shredded tobacco leaves with a particle size between 5 mm and 10 mm are used, reconstituted tobacco is classified as conventional tobacco. and non-conventional cigarettes.

WO 2016/050469, WO 2016/050470, WO 2016/050471, WO 25 2016/050472 describe known technologies for the production of reconstituted tobacco, but these require large plants and high energy consumption for conveying the slurry. , which is certainly flexible in consistency to a sheet of tobacco as a product. It can be sufficiently pointed out that the length of the drying oven can reach up to 100 m.

Another disadvantage of the known technology for producing reconstituted tobacco using by-products is the fact that the formation of the starting sheet from the slurry film is quite irregular, since the starting product is not homogeneous and the distribution on the steel is not uniform. and, therefore, it is not possible to reel or cut the reconstituted tobacco sheet regularly.

WO 2019/157576 describes a method for producing a strip of recycled vegetable material, wherein between a pre-lamination step and a final lamination step, to obtain a homogeneous mass and to provide a final lamination, Remixing of the pre-laminated sheets is provided in the mixer.

WO 2016/067226 discloses a first drying unit, a grinding unit, a mixing unit of solid components (i.e. solid powder of tobacco powder and natural binder), a mixing unit of liquid components (i.e. liquid/nano containing propylene glycol and glycerin). gel), a unit for mixing a solid mixing component with a liquid mixing component to obtain a film of 0.15 to 0.3 mm in 1 to 3 laminated units, and a dryer for reducing the moisture content of the film. describe

It is an object of the present invention to use known techniques for producing sheets and strips of reconstituted tobacco in sectors not yet used, while at the same time eliminating the disadvantages already highlighted in certain sectors and those that are more emphasized in this new sector of use. to be modified to do so. In particular, the present invention aims to produce homogeneous sheets and strips of nicotine-free vegetable fibers, in particular potato, hemp, tea, chamomile, mint, sage, rosemary, eucalyptus and the like.

Another object of the present invention is to produce sheets of homogeneous vegetable fibers in plants of much smaller size than those known for producing reconstituted tobacco.

Another object of the present invention is to produce a homogeneous sheet of vegetable fiber with limited energy consumption.

Another object of the present invention is to produce a sheet of homogeneous vegetable fibers using a device already available on the market, in part, even though it has never been used in this particular technical field.

Another object of the present invention is to produce a sheet of homogeneous vegetable fiber with properties suitable to meet different market demands.

Another object of the present invention is to produce a sheet of homogeneous vegetable fiber by operating at low temperatures to preserve all the aromas of the raw materials used.

According to the present invention, the above and other objects which will arise from the description below are achieved jointly or separately by a method for producing a homogeneous sheet of nicotine-free vegetable fiber according to claim 1 .

In particular, the process according to the invention for producing a homogeneous sheet of nicotine-free vegetable fiber is characterized by the fact that it comprises carrying out the following steps in sequence.

- crushing vegetable fibers until the solid component of the raw material has a particle size of about 20 to 220 μm, preferably about 80 to 180 μm,

- the lysate thus obtained is mixed with water, optionally powdered cellulose, one or more binders and one to form an aerosol, until a mixture with a liquid content of about 30-50%, preferably about 35-40% is obtained Mix with the above substances,

- the mixture is provided in a first lamination to obtain a continuous strip having a thickness of about 1-20 mm, preferably about 1-10 mm,

- the strip already provided in the first lamination is subjected to a series of further lamination steps until a strip having a very constant thickness of about 90 to 280 μm, preferably about 140 to 200 μm is obtained,

- The strip is dried until it retains about 8-15% liquid.

The present invention will appear more clearly in some of the preferred embodiments described below for illustrative and non-limiting purposes with reference to the accompanying drawings.
1 is a general schematic view of a plant for producing homogeneous sheets of vegetable fibers according to the present invention.
Fig. 2 is a view showing a feeding section when a sheet of vegetable fiber is obtained from a plant leaf.
Fig. 3 is a view showing a feeding section in the case where sheets of vegetable fibers are obtained from stems and branches of plants.
Figure 4 is a schematic diagram showing in part a plant with two separate pre-treatment lines for the leaves and stems and branches of the plants.
Figure 5 shows the crushing, mixing and storage section.
6 is a schematic diagram of one of the cylinder refiners.
7 is a plan view illustrating a stratification section in a particular embodiment.
8 is a schematic diagram showing a hot air dryer.
9 is a schematic diagram showing a hot air dryer in another embodiment.

As can be seen from the figure, the process according to the present invention for producing a homogeneous sheet of nicotine-free vegetable fiber is carried out until the vegetable fiber is transformed into a continuous belt, which is sent to the subsequent processing or packaging of the input raw material. It is the use of a plant containing some sections intended for manipulation. The raw material used may consist of, for example, potato, hemp, tea, chamomile, mint, sage, rosemary, eucalyptus and the like.

Specifically, a plant for carrying out the method according to the present invention comprises:

- a pre-treatment section of the starting solid product (leaves, stems and branches of plants) to prepare it for subsequent milling treatment;

- a crushing and storage section awaiting subsequent mixing with appropriate process liquids;

- a mixing section of solid and liquid materials to obtain a homogeneous mixture with a more or less dense consistency;

- a section for converting a mixture, in particular a plurality of parts of said mixture, into a continuous belt;

- a rolling line for the continuous strip to reduce to the desired final thickness,

- the dry section of the laminated web.

Preferably, the preparation and pre-treatment section of the solid starting products is the pre-treatment section of the plant leaves used for preparing the vegetable fiber sheet (Figs. 2 and 4) and/or the preparation of the stems and branches of the plants and It may include a preliminary processing section (Figs. 3 and 4).

In the case of preparing and pre-processing plant leaves ( FIGS. 2 and 4 ), the relevant section includes a feeding station with a bench (2) for unrolling piles of vegetable leaves, which are usually equipped with them and convey them to a mill (4), have.

Preferably, the output of the mill (4) is connected to the cyclone (8) via a pneumatic conveying line (6), where conveying air is separated from the solid product and the solid product is conveyed to a sieve vibrator (10) The microparts are separated from the rest of the product. The outlet of the fine part is directly connected to a mill (12), preferably of cryogenic type, while the outlet of the remaining parts of the product is fed to a traditional twin lever machine (14) , removes the unremoved twine from the clump of vegetable leaves.

The output of the twin lever machine 14 is directed to a sorting chamber 16 for separating heavy debris from the vegetable leaves, which includes a pneumatic transfer line 18, a cyclone 20, metal for removing any metal objects. A belt conveyor 22 equipped with a detector 24, a weighing system 26 (master scale) and a pneumatic transfer line 28 are conveyed to the storage and mixing silo 30, from which another pneumatic conveyor 32 It can be conveyed to the cryogenic mill 12 through. These silos 30 are sized to contain the amount of product required to form a batch according to the particular recipe being prepared.

On the other hand, if a preparation and preliminary treatment section is provided to act on the stems and branches of plants used to prepare sheets of vegetable fibers (Figs. 3 and 4), it is a tilter (34) for containers containing stems and branches of plants. ), a feeder 36 which sends them to a vibratory conveyor 38 to separate the heavy objects from them, and a pneumatic conveying line 44 to convey them to the hammer mill or crusher 42 at the place where they are crushed. do.

The hammer mill or crusher 42 has an outlet connected in turn to one or more storage silos 48 by means of a pneumatic transfer line 44 equipped with a cyclone filter 46.

The output of the storage silo 48 is in turn connected via a screw conveyor 50 to a metering system 52 (slave scale), which doses the shredded stems and branches in the proportion required for the particular recipe to be prepared, and then pneumatically It can be moved to the storage and mixing silo 30 via a conveying line 53 and then conveyed via a pneumatic conveying line 32 to a cryogenic mill 12, where the various products received can be transported to about 20- Grind to an average particle size of 220 μm, preferably about 80-180 μm.

Different types of mills can be used, but it is advantageous to use a cryogenic pin mill, which allows the product to be kept at low processing temperatures and thus retains the aroma of the raw materials used.

The pin mill itself is traditional and comprises in a closed structure a stationary disk and a rotating disk, or two oppositely rotating disks provided with facing and partially interpenetrating pins. It is itself a traditional device, and although FIGS. 4 and 5 show the entire area at 12, neither the characteristics of the internal structure nor the mode of operation are shown.

Preferably, pin mill 12 is arranged to perform cryogenic grinding, ie milling in the presence of liquid nitrogen.

As mentioned, in plants for producing sheets of vegetable fiber, the cryogenic pin mill 12 inherently has some advantages over traditional mills due to the different ways of processing the comminuted product. In fact, milling at room temperature may degrade the quality of the product, but milling in the presence of liquid nitrogen can retain the physical and chemical and organoleptic properties of the product.

The amount of liquid nitrogen used in a cryogenic milling process is an important aspect to consider when examining the pros and cons of the process and can vary depending on the material being processed. Liquid nitrogen at a temperature of -175 ° C is injected into the product in the chamber of the screw conveyor 55 supplied to the mill 12, and the residence time in contact with nitrogen is about 2 to 5 seconds, which time is also ) is the movement time of the product within Since the temperature of the product leaving the mill 12 is advantageously less than 10° C., the nitrogen vapor, which is released almost instantaneously upon contact with the raw material to be cooled, flows countercurrently through the entire supply system of the mill, providing the desired pre-cooling effect. do. The pre-cooling system and the flow of liquid nitrogen within the mill are controlled by thermocouples, allowing the cryogenic milling process to be fully automated.

In summary, the positive factors for cryogenic milling are:

- high yield;

- without breaking or tearing the molecular structure, improving the quality of the final product;

- reduced energy required;

- improving the quality of the final product;

- reduction of waste from overheating and oxidation;

- a homogeneous and fine final product;

- Less amount of material to be reprocessed in the milling system.

Preferably, the outlet of the cryogenic fin mill 12 is connected to a fluidized bed sieve 54, which sieve has the function of separating the milled products, which come from the mill itself and are usually necessarily present from a larger size. has an average particle size of about 20-220 μm, preferably about 80-180 μm.

Therefore, preferably, the fluidized bed sieve 54 has a function of sorting the product after separation between 20 μm and 220 μm, and reintroducing that having a fraction greater than 220 μm into the mill 12, which is pneumatically conveyed ( 56) to one or more mixing and storage silos 58.

Advantageously, the outlet of the mixing and storage silo 58 is connected by a pneumatic conveying line 60 to a cyclone filter 62 having the function of breaking up dusty air, in particular separating dust, It can then be recovered from the air and reintroduced into the circulation, where it can be discharged.

Preferably, the outlet of the cyclone filter 62 is fed via a continuous dosing system 66, preferably with a screw, to a mixer 64 which may be of various types, eg horizontally inclined or vertical spiral.

Mixer 64 is supplied with metered amounts of shredded raw material, water, one or more binders and one or more substances forming an aerosol, and a mixture having a liquid content of about 30-50%, preferably about 35-40%. configured to obtain

In particular, liquid or humidity values indicated herein are intended to be determined according to a moisture based measurement system. In particular, the humidity value is defined as the percentage of water contained in the total mass of the corresponding product, ie the percentage ratio between the amount of water and the total mass of the assembly. Preferably, these values are obtained using conventional methods described in the literature for determining the amount of moisture in a product, for example "Tobacco Moisture, Water, and Oven Volatiles—For common moisture determination methods used in the tobacco industry". Status Report" [Nils Rose et al. "Analytical and Bioanalytical Chemistry" (July 1, 2014, pages 1-16)].

Preferably, one or more ducts for the influent, a material for forming the aerosol (eg glycerine) and one or more binders (binders) are connected to the mixer 64 . Preferably, one or more inlet ducts may be provided for additives required for the particular recipe being prepared.

Specifically, the plant comprises at least one storage tank 68 for aerosol-forming substances and at least one pre-mixer 70, into which substances for aerosol-forming can be introduced, preferably a plurality of additives in suitable proportions. It may form a liquid that is dosed and introduced into mixer 64.

In order to increase the resistance of the finished product sheet and at the same time increase the density of the product itself, it is desirable to introduce the powdered cellulose into the mixer 64 along with the other ingredients of the mixture. Preferably, the cellulose powder used consists of organic fibers obtained from natural cellulose and not compounds derived from cellulose. The powdered cellulose thus added preferably has a particle size of 50 to 100 μm, and is preferably included in a proportion of between 2% and 10% by weight relative to shredded tobacco.

The powdered cellulose added is predominantly or exclusively of natural origin. In particular, the powdered cellulose thus added is neither synthetic nor obtained by chemical treatment.

Preferably, the powdered cellulose added in this way does not have a binding function, since cellulose is much cheaper than tobacco, but has and has the function of reducing the specific gravity of the final product and reducing the solid content of the tobacco, thus reducing the cost of the finished product. save on In addition, the addition of cellulose increases the tensile strength to reduce the brittleness of the final product, and thus facilitates processing, which is particularly useful when a pleated sheet of the final product is obtained.

This powdered cellulose, placed in bags or large bags prior to use, can be directly fed into a blender 64 (FIG. 1), in which case it is poured into a conventional hopper and then fed into a cyclone filter 72, preferably of screw type. It is introduced into mixer 64 in metered amounts via continuous dosing system 73.

Alternatively, the powdered cellulose may be introduced back through a cyclone filter 72 and continuous dosing system 73 to a pneumatic transfer line 28 that feeds the mixing and storage silo 30, from which an air transfer line 32 ) and is conveyed to mill 12 (FIG. 4) together with the other components of the mixture present in the line itself. The contents of the mixing storage silo 30 from the mill 12 are then transferred via a pneumatic transfer line 56 to the silo 58, from which a pneumatic transfer line 60, cyclone filter 62 and metering device 66 ) and enters the mixer 64.

Examples of preferred materials for aerosol formation (particularly visible aerosol formation) include polyhydric alcohols such as glycerin, propylene glycol, triethylene glycol and tetraethylene glycol, aliphatic esters of mono-, di- or poly-carboxylic acids such as : methyl stearate, dimethyl dodecandium and dimethyl tetradecanoate) and mixtures thereof. Suitably, glycerin, propylene glycol, triethylene glycol and tetraethylene glycol may be mixed together to form an aerosol-forming material. The aerosol-forming material may also be provided as part of the binder (eg when the binder is propylene glycol alginate). Advantageously, suitable combinations of materials for forming aerosols may also be provided.

Preferably, the at least one binder is hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, microcrystalline cellulose, methylcellulose, carboxymethylcellulose (CMC), corn starch, potato starch, guar gum, locust bean gums, pectins and alginates (eg ammonium alginate and sodium alginate).

Preferably, the binder and the powdered cellulose to be added are defined by different materials. Advantageously, the powdered cellulose mainly serves to form a three-dimensional framework with a high thickening effect, similar plastic behavior and good liquid holding capacity, while the binder serves exclusively or mainly to bind together the various components to be mixed. .

Advantageously, the outlet of the premixer 70 is connected to the inlet of the hydrator 74 and the other inlet is connected to the water supply line 76 and the compressed air supply line 78.

Preferably, the outlet of the mixer 64 leads to a unit 80 forming a mixture to obtain a plurality of portions 82, which are preferably lumpy and separate from each other. Advantageously, the forming unit 80 comprises a pair of forming cylinders 84, preferably comprising grooves parallel to the axis of the cylinders themselves, to pick up the mixture at the inlet and feed the portion 82 at the outlet. It is done. Advantageously, the unit 80 is also configured to perform a roughing of the mixture, for which purpose there is preferably an internal lump breaker, provided at the bottom of the pair of forming cylinders 84. A hopper 86 is included.

Advantageously, at the exit of the forming unit 80 a conveyor belt 88 is provided for conveying the portion 82 to the first rolling unit 90 .

Preferably, the first rolling unit 90 includes a lobe feeder 92 for homogenizing the mixture formed by section 82 .

Advantageously, along the transfer path from the forming unit 80 to the lobe feeder 92, it has the function of removing any metal parts that may still be present in the mixture and may damage subsequent processing units. Other metal detectors 94 may be provided. These metals are conveyed along a separate path before entering the lobe feeder 92 and collected in an appropriate container 96.

Lobe feeder 92 includes a series of lobe feed rollers, between which portions 82 are passed (from forming rolls 84 of forming unit 80) to between a pair of rolling rolls 98. Mixed together and homogenized before being pressed in, the rolls are configured to form a continuous strip of about 1 to 20 mm in thickness, preferably about 1 to 10 mm in thickness.

The lobe feeder 92 thus advantageously causes homogenization of the product, which may have agglomerates, leaving the forming unit 80. Also advantageously, the lobe feeder 92 advances the product and forces it into an inlet between a pair of laminating rolls 98 .

Accordingly, the first lamination unit 90 preferably comprises a homogenization module defined by a lobe feeder 92 and is disposed immediately upstream with respect to a prelamination module defined by at least one pair of lamination cylinders 98 and , they are configured to form a continuous strip having a thickness of about 1 to 20 mm, preferably about 1 to 10 mm. Advantageously, the strip thus obtained has greater elasticity.

Advantageously, in a version not shown of the plant, the rolling line 100 may be provided directly downstream of the lobe feeder 92 . In particular in this case, the rolling line receives a single-layer continuous strip having a thickness of about 1 to 20 mm, preferably about 1 to 10 mm, coming out of the first lamination unit 90 with a lobe feeder 92 .

Preferably, the lamination unit 102 may be provided downstream of the first lamination unit 90 and upstream of the lamination line 100 . Preferably, the single-layer continuous strip of about 1 to 10 mm thickness coming out of the first lamination unit 90 is configured to be arranged in several layers, and converted into a multi-layer belt of about 2 to 20 mm thickness, of the rolling line 100. sent to the entrance

Preferably, the stratification unit 102 is composed of an upstream conveyor belt 104, which preferably has a function of placing a product belt on a lower downstream conveyor belt 106 belonging to the rolling line 100, for example Pick up and fold itself multiple times, so as to be stacked on the downstream conveyor belt 106. Preferably, the upstream conveyor belt 104 is lifted relative to the downstream conveyor belt 106 and makes a continuous motion moving forward relative to the support structure, while simultaneously performing alternating motion with its longitudinal axis parallel to the support structure. .

Advantageously, the stratification unit 102 feeds the subsequent and lower tier rolling line 100 and, depending on the type of plant, conveyor belt 104 upstream of the stratification unit 102, advantageously at the entrance of the rolling line 100. It can be positioned parallel or perpendicular to the downstream conveyor belt 106 on the belt. In particular, if the conveyor belt of the rolling line 100 has a width substantially equal to the width of the product belt exiting the stratification unit 102, the upstream conveyor belt 104 is the transfer conveyor of the lamination line 100 (FIG. 1). If the conveyor belt of the lamination line 100 is wider than the product belt exiting the stratification unit 102, while running parallel to the belt 106, the upstream conveyor belt 104 is the lamination line 100 ( It is preferably arranged perpendicular to the infeed conveyor belt 106 of FIG. 7). In this way, alternating motions of the conveyor belts 104 upstream of the stratification unit 102 relative to the support structure can distribute the product belt across the entire effective width of the rolling line 100 .

In both cases, however, the alternating motion of the support structure of the conveyor belts 104 upstream of the stratification unit 102 causes stratification of the product belts, which on the lower first conveyor belt 106 of the stacking line 100 Leaving the first rolling unit 90, it forms a laminated belt with a width substantially equal to the useful width of the rolling line itself.

The rolling line 100 is formed by a plurality of rolling stations, each comprising a pair of cylinders 108, defining tapered passages therebetween to progressively reduce the strip thickness of the product being processed. In particular, the lamination line 100 is configured to progressively form a continuous strip to a thickness of 90 to 280 μm, preferably about 140 to 200 μm.

Preferably between each rolling station and the next there is provided a conveyor belt 110 having a length of about 1.5 to 2 m, i.e. a length sufficient to stop the product before it is subjected to the next rolling process. .

Advantageously, the rolling line 100 is completed with one or more calibrating stations each forming laminated rolls by means of a pair of calibrating rolls 112 .

It is provided that the straightening roll 108 and possibly the straightening roll 112 can be heated so that the drying step can be started already during lamination. Advantageously, downstream of the rolling line 100 is a dryer 114 with air recirculation to bring the liquid content of the rolled strip to about 8-15% (FIG. 8). Advantageously, dryer 114 can be divided into two units 116, 118 arranged in series with each other (FIG. 9). In this case, an upstream unit 116 is provided for carrying out the first drying step, and a steel belt or net belt conveyor for conveying the product leaving the rolling line 100 is installed therein. A downstream unit 118 is provided for carrying out the second drying step and subsequent cooling step, and a network belt conveyor is installed therein.

Dryer 114 also preferably has sensors 120, preferably infrared, at its inlet and outlet that monitor product along its entire length.

To prepare sheets of plant fibers starting with vegetable leaves, cartons containing the leaves are placed on an undressing bench 2 ( FIG. 2 ), where one bale of vegetable leaves is removed from the carton. It is removed and sent to a mill 4 whereby the leaves themselves are reduced to a substantially uniform size between 5 and 10 mm.

Advantageously, the pulverized product is then conveyed along a pneumatic conveying line (6) to a cyclone (8) where it is separated from the air and dropped into a vibrator (10).

Here, the separation of fine parts that are sent directly to the cryogenic mill 12 occurs, and the remaining parts pass through the twin lever machine 14, and then the sorting chamber to separate heavy objects from the crushed leaves ( 16), a pneumatic conveying line, a cyclone 20, a conveyor belt 22 with a metal detector 24 for removing metal objects, a weighing system 26 (master scale) and a pneumatic conveying line 28 ) Through, it can be transferred to the storage and mixing silo 30, from which it can be transported to the cryogenic mill 12 through the pneumatic transfer line 32.

In the case of producing a vegetable fiber sheet using plant stems or branches as raw materials, the relevant containers are placed in a tipper 34 (FIG. 3) and sent to a vibration conveyor 38 to remove heavy objects. Then, the stems and branches are transferred to the hammer mill 42 through the pneumatic line 40, and the hammer mill cuts them down to a size of 5-8 mm.

From here, the chopped stems and branches separated by cyclones 46 from the conveying air are transferred to the storage silo 48, where various types from different qualities of vegetables are picked up and delivered via screw conveyor 50 to dispensers ( 52), and the dispenser 52 dispenses them according to the specific recipe to be prepared.

Stems and branches chopped and dosed in appropriate amounts are transported from here to the cryogenic mill 12 via pneumatic lines.

If the plants are designed to process both vegetable leaves and stems and branches, in the pneumatic transfer line 28 feeding the mixing and storage silo 30, out of the storage silo 48 into the pneumatic transfer line 53 (Fig. 4).

Irrespective of the type of raw material being produced, and regardless of the nature of the solid part of the raw material introduced into the grinding unit, the milled product from the fluidized bed sieve 54 supplied by the cryogenic mill 12 has a diameter of about 20 to 220 μm. , preferably with an average particle size of about 80 to 180 μm. This is sent to the mixing and storage silo 58, where the product can be recovered and conveyed to mixer 64 as needed.

In addition to the milled raw material, any cellulosic and all solid products coming out of the common mixing and storage silo 30 are also introduced with water, at least one binder and at least one substance to form an aerosol. Advantageously, compressed air and other additives may also be introduced.

The whole is then mixed together to form a slurry having a liquid fraction (humidity) of about 30-50% by weight, preferably about 35-40% by weight on a wet basis, i.e., on a more or less dense consistency basis.

Preferably, the mixture thus obtained is conveyed to a forming unit 80, from which a portion 82, preferably in the form of a mass, is continuously discharged.

This portion of the mixture 82 exiting the forming unit 80 is passed to a first rolling unit 90 configured to homogenize the mixture and feed a continuous strip having a thickness of about 1-20 mm, preferably about 1-10 mm at the exit. transported appropriately.

This continuous strip originating from the first lamination unit 90 may be conveyed directly to the lamination line 100 or, more advantageously, folded upon itself as it passes through the lamination unit 102 to form a lamination line 100 ) can be placed on the inlet belt of

Preferably, as mentioned, lamination is obtained by dropping a continuous belt onto a conveyor belt 104 upstream of a lamination unit 102 made to advance relative to a moving support structure by a reciprocating motion, so that the product belt moves downstream. It is placed in several layers on the conveyor belt 106, ie at the entrance of the rolling line 100. Depending on the reciprocating direction of motion of the support structure of the conveyor belt 104 of the plant and stratification unit 102, the product belt is formed in several para layers (perpendicular to or along the longitudinal direction of the rolling line 100) 11) placed on it.

Preferably, at each passage of the rolling line 100 from one station to another, the output straightening cylinder has a very constant desired thickness of about 90 μm to 280 μm, preferably about 140 μm to 200 μm. The product strip is reduced in thickness until the desired thickness corresponding to (112) is reached. Also, at the exit of the rolling line 100, when the lamination cylinder 108 is heated and water removal has already been initiated during lamination, the strip has a liquid content of less than 20% or even less than 15%.

The web of product leaving the rolling line 100 is then subjected to drying in a dryer 114 to a liquid content of about 8-15%.

Desirably, the dryer 114 is recirculating air, which is somewhat advantageous both in terms of manufacturing complexity, in terms of overall dimensions, and in terms of energy consumption, compared to dryers traditionally used in reconstituted tobacco manufacturing plants. This is much denser and much more stable than the products processed by the plants described above, since traditional plants process a very fluid, less stable product (slurry). As a result, while plants processing the slurry require traditional irradiation and conduction dryers, the plant just described has a network belt conveyor or steel belt conveyor for the first drying stage and a second drying stage. and a recirculating air dryer 114 with a combination system of a net belt conveyor for the cooling step. Thus, with the same performance, reduced dimensions can be achieved (about 45 m compared to over 100 m in conventional dryers) and low energy consumption due to the small amount of water that has to be removed (about 1000 kg/hour of steam/hour compared to traditional dryers). compared to over 5000 kg/hour steam in dryers).

Preferably, at the exit of dryer 114, the product is ready to be wound onto a reel for its intended use, or cut into threads of predetermined dimensions or cut into sheets for its intended use. has been

Preferably, in the method according to the invention, the homogenization of the mixture is carried out predominantly or exclusively by the lobe feeder 92, in any case always and only upstream, preferably directly upstream of the pre-rolling module, which The homogenized mixture is converted into a continuous strip with a thickness of about 1 to 20 mm, preferably about 1 to 10 mm, and sent to the inlet of the final rolling line 100.

In particular, when the homogenized mixture is converted into a continuous strip having a thickness of about 1-20 mm, preferably about 1-10 mm, the strip is no longer remixed, but sent to the rolling line 100 in strip form to obtain the desired thickness. and this thickness has a very constant value of about 90 to 280 μm, preferably about 140 to 200 μm. Advantageously, the fact that the rolling line 116 receives the strip at the inlet rather than the deformed mixture makes it possible to ensure a constant inlet flow, the subsequent rolling step improves the accuracy of the sheet thickness and the lamination cylinder of the line itself. (108) can be reduced, reducing cost as well as dimensions of the entire plant.

Preferably, the plant may include upstream, as an alternative to or in addition to the forming unit 80, a cylinder refiner 122, which has the task of bringing the solid components of the mixture to a particle size not exceeding 20 μm.

The refiner (FIG. 6) includes a plurality of cylinders 124 arranged sequentially in close proximity to each other in a closed vessel, defining corresponding grinding slots. The lower cylinder 124', whose axis is mounted out of the plane containing the axis of all the other cylinders 124, serves as a feeder of the mixture, which is taken from the bottom of the vessel and passed between the lower cylinder and the cylinder directly above it, and the other cylinder 124'. It moves upward in a way that follows between all cylinders. The various pairs of cylinders 124 that the mixture passes therebetween rotate at different speeds, and the mixture passes between each pair of cylinders 124 to elongate in the sense that the upper cylinder rotates at a higher speed than the lower cylinder and cooperates. This will reduce the particle size of the mixture itself. Indeed, one of the basic parameters for the success of the refining process is the different speeds between the different cylinders 124 upon which the passage of the entire mixture mass through the grinding slot depends.

The pressure between the cylinders is hydraulically controlled.

All cylinders 124 are cooled by cooling water circulating inside each cylinder, in this way counteracting the heat generated in the mixture due to the motion of the cylinders and friction from rubbing with the product. In this way, the temperature of the product mass is reduced until reaching 25°C.

Thanks to the refiner 122 described above, the frictional action exerted on the mixture by the cylinder 124 develops a significant binding action of the cellulosic fibers contained in the raw material, which carries with it the dual advantage of producing the aromatic constituents and provides the necessary binding There is no need to introduce more fibers into the mixture to get the effect.

The operation of the plant in this other embodiment is that the shredded raw material coming from the preparation and pre-processing station is fed to the cryogenic fin mill 12 in proportionally dosed amounts according to the recipe obtained, from which about 20 to 220 μm, It is preferably provided in a particle size of about 80 to 180 μm.

The product is then conveyed in the manner previously described to mixer 64, where a product mixture is formed as described above.

The mixture thus obtained is supplied to the cylinder refiner 122 which has the task of making the solid components of the mixture into a particle size not exceeding 20 μm. In this way, the frictional action exerted on the mixture by the cylinders 124 of the refiner 122 develops a significant binding action of the raw material, in particular the cellulosic fibers contained in its stems, branches and ribs, which on the one hand impairs the quality of the product. It has the double advantage of developing the aromatic component and, on the other hand, eliminating the need to introduce more fibers into the mixture to achieve the necessary bonding effect.

1 schematically shows the location of a purifier 122 between a mixer 64 and a forming unit 80, the present invention also allows the purifier 122 to be an alternative to the forming unit 80; The mixture exiting the case refiner 122 is conveyed directly to the first rolling unit 90 to continue the treatment cycle according to the previously described method.

Claims (26)

A method for producing a homogeneous sheet of nicotine-free vegetable fiber, the method comprising:
- Grinding the solid component of the raw material containing nicotine-free vegetable fibers to a particle size of about 20 to 220 μm, preferably about 80 to 180 μm,
- mixing the ground material thus obtained with water, one or more binders and one or more substances forming an aerosol, until a mixture is obtained with a liquid content of about 30-50%, preferably about 35-40%,
- the mixture is applied in a first lamination to obtain a continuous strip having a thickness of about 1-20 mm, preferably about 1-10 mm,
- the strip already provided in the first lamination is subjected to a series of further lamination steps until a strip having a very constant thickness of about 90 to 280 μm, preferably about 140 to 200 μm is obtained;
- the strip is dried until it retains about 8-15% liquid. 2. Method according to claim 1, characterized in that the dry continuous strip is wound into threads of predefined dimensions or cross-cut or shredded. The method according to claim 1 or 2, characterized in that the solid component of the raw material is pulverized and crushed. The method according to any one of claims 1 to 3, characterized in that the solid component of the raw material is crushed by a mill. 5. Method according to any one of claims 1 to 4, characterized in that the solid component of the raw material is ground in a cryogenic pin mill (12). 6. A method according to any one of claims 1 to 5, characterized in that the powdered cellulose is also mixed with other substances forming a mixture. 7. The method according to any one of claims 1 to 6, characterized in that powdered cellulose composed of organic fibers obtained from natural cellulose is used. 8. The method according to claim 6 or 7, characterized in that the slurry is formed of powdered cellulose having a particle size of 50 to 100 [mu]m. 9. The method according to any one of claims 1 to 8, characterized in that the mixture is formed of powdered cellulose in a proportion of 2% to 10% by weight of the raw material. 10. The method according to any one of claims 1 to 9, characterized in that prior to mixing the mixture with the ground component of the raw material, the ground component is mixed with the powdered cellulose. 11. The method according to any one of claims 1 to 10, wherein the mixture formed by the shredded product, powderable cellulose, water, at least one binder and at least one substance for forming an aerosol comprises:
- a roughing step carried out through at least one pair of grooved cylinders 84 and/or
- subjected to a purification step carried out by passing through at least one pair of purification cylinders (124, 124') until the particle size reaches a level not exceeding 20 μm. 12. Method according to any one of claims 1 to 11, characterized in that the mixture is subjected to a homogenization and shaping step before being subjected to the first rolling step. 13. The method according to any one of claims 1 to 12, wherein the mixture is subjected to a homogenization and shaping step for transformation into a continuous strip having a substantially constant width between 100 and 2000 mm and a thickness between 1 and 10 mm, subject to the first lamination step. 14. Method according to any one of claims 1 to 13, characterized in that the mixture is subjected to a homogenization and shaping step for transformation into a series of parts (82) and then to the first rolling step. 15. The method of claim 1 , wherein a unit (90) comprising a lobe feeder (92) and at least one pair of rolling cylinders (98) is used to perform a first rolling step of rolling the mixture. characterized by a method. 16. The method according to any one of claims 1 to 15, characterized in that the first layer comprises a homogenization step performed before obtaining a continuous strip having a thickness of about 1-20 mm, preferably about 1-10 mm. How to. 17. The method according to any one of claims 1 to 16, wherein the mixture is first subjected to a shaping step to transform it into a series of parts (82) and then from these parts a thickness of about 1-20 mm, preferably about 1-20 mm. characterized in that the portion (82) is subjected to a step of homogenizing before obtaining the continuous strip having a thickness of 10 mm. 18. Method according to any one of claims 1 to 17, characterized in that the mixture is mainly or exclusively homogenized by a lobe feeder (92) located at the inlet of at least one pair of rolling rolls (98). 19. A method according to any one of claims 1 to 18, characterized in that at the exit of the first stack a single layer tape having a thickness of about 1-10 mm is obtained. 20. The method according to any one of claims 1 to 19, wherein layering is provided until a multilayer strip of about 2 to 20 mm thickness is obtained, before subjecting the strip already provided in the first lamination to a series of further lamination steps. characterized by a method. 21. A method according to any one of claims 1 to 20, characterized in that in the series of additional rolling steps, the mixture is allowed to lie between one rolling station and the next. 22. A method according to any one of claims 1 to 21, characterized in that the lamination is carried out using a pair of at least partially heated cylinders (108). 23. A method according to any one of claims 1 to 22, characterized in that the laminated strip is dried by passing through a recirculating air dryer (114). 24. A method according to any one of claims 1 to 23, characterized in that vegetable fibers of at least one of vegetable substances such as potato, hemp, tea, chamomile, mint, sage, rosemary and eucalyptus are used. 25. The method of claim 1 , wherein the first lamination comprises a homogenization module of the mixture located immediately upstream to the pre-rolling module defined by at least one pair of lamination rolls (98). characterized in that the roll is configured to form a continuous strip having a thickness of about 1-20 mm, preferably about 1-10 mm, performed in units of one stack (90). 26. A method according to any preceding claim, characterized in that the homogenization module comprises a lobe feeder (92).

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