EP1177730B1 - Method and device for conditioning cut tobacco materials - Google Patents

Abstract

The assembly to condition chopped tobacco, using steam to deliver heat and moisture, has a chamber (3) where the tobacco material drops freely downwards. The chamber has a continuous operation, with ring jets (2) to spray steam downwards at the tobacco falling past them. The chamber is at a constant pressure over atmospheric levels, and has especially an absolute pressure of ≥ 1 bar at 2-10 bar. The jets deliver saturated steam at a temperature of 100-200 degrees C.

Description

The invention relates to a method for conditioning comminuted Tobacco materials by heating and moistening with water vapor in the The preamble of claim 1 specified genus and a corresponding device the type specified in the preamble of claim 5.

Here are the term "shredded tobacco materials" for example entripptes Tobacco leaf, tobacco ribs, tobacco stems, each cut or fibered, recycled tobacco and tobacco by-products such as TV and ZHV winnowings be understood.

Such processes are mainly used for the preconditioning of comminuted Tobacco materials used as the first stage of an expansion process to the to increase so-called "filling capacity" of the tobacco material.

Freshly harvested, green tobacco leaves contain relatively high levels of water, which by means of various methods known as "curing methods" to less than 10% residual water content is reduced. This processed raw tobacco is in the Factories for the production of, for example, cigarettes or other luxury foods Base brought by tobacco.

However, the processing chain from the green leaf to the raw tobacco leads to a strong Shrinkage of tobacco materials, and such a reduction in volume affects detrimental to the filling ability.

Therefore, various methods have been developed, this volume reduction at least partially reversing, taking advantage of the fact that that the cell scaffold of shredded tobacco materials originally in the leaf can enclose existing volumes.

In the known expansion processes a distinction is made between two case groups, viz the high order processes in which the tobacco in an autoclave with a light volatile propellant such as carbon dioxide or nitrogen, resulting in suitable process control increases in filling capacity in the field of 100%, compared with the measured value after cutting, or Low order processes which are subject to preconditioning with steam Drying followed, for example, in a current dryer, a vortex dryer or a drum dryer. The drying follows the so-called post-conditioning, the includes rewet, sieve, and cool. Through low order processes leaves the filling capacity increases by up to 50%.

The present invention is concerned with a low order expansion process a preconditioning for preheating / pre-wetting the tobacco material with Steam and a subsequent drying can be performed.

There are already known various low order expansion methods. That's how it shows DE 37 10 677 C2 an expansion device with a rotary valve for the Supplying the tobacco material to an expansion chamber through a portion the rotary valve is formed. A hot gas consisting of air and water vapor is introduced into the expansion chamber, so that the tobacco material under pressure drop to at least 50 m / sec at a residence time of the tobacco material in the Expansion chamber of less than 0.1 s is accelerated.

WO 99/23898 describes a device for saucing and humidifying tobacco: The tobacco is introduced through an airlock in the device, so no Air can enter the device. The tobacco falls down through the device and is made of side nozzles with steam / water / casing and other materials sprayed. The pressure of the nozzles is in the range of 0.1 to 10 bar. The treatment takes place under atmospheric pressure, as from the discharge side no closure of the Treatment room is provided.

WO 97/04673 discloses a method for the expansion of tobacco ribs, which in one Pressurized container to be pressurized by saturated steam until all Cells of the ribs are moistened. Thereafter, the pressure is released quickly, causing the Cells "explode". Due to the discontinuous, so in batch mode As a result, this system is not economically optimal.

A method and a device of the specified type finally go from the DE 197 34 364 A, wherein comminuted tobacco material via a rotary valve is introduced into a chamber. In this chamber, the tobacco material falls freely below, radially through 'a rotating beam curtain of the conditioning medium. For this purpose, within the chamber, a conveyor, namely a Winnoverwalze arranged around a substantially transverse to the direction of flow of the tobacco extending axis rotates and substantially radially emerging nozzle openings for having the conditioning medium.

This Winnover roller also serves to make it more or less clumped together Fibers existing tobacco to dissolve and separate.

On the output side, an additional rotary feeder may be provided (see FIG. 4), the tobacco to a vibratory conveyor for onward transport to a Drying device transferred.

A disadvantage of this type of preconditioning is the mechanical stress of the Tobacco to dissolve the lumps on the during heating and Humidification melting fats attributable to the surface of the tobacco particles are.

The invention has for its object to provide a method and an apparatus for To provide (pre-) conditioning of shredded tobacco particles in which the above mentioned disadvantages do not occur. In particular, a method and a Device to be proposed, while maintaining the advantages of a Continuous continuous process no mechanical stress require sensitive tobacco particles.

This is indicated by the features indicated in the characterizing parts of claims 1 and 5 Features achieved.

Advantageous embodiments are defined by the associated subclaims Are defined.

The advantages achieved by the invention are based on the following considerations: Increase in filling capacity, measured in comparison to the value of the filling capacity after Cutting the tobacco can be influenced by the increase in humidity with which the preconditioned tobacco enters the dryer, that is the so-called Dryer inlet moisture. For given dryer parameters, especially given Dryer geometry and again solid dryer length increases the filling capacity the increase of the drier entry moisture.

In addition, increasing the inlet temperature of the tobacco into the dryer has a positive effect Effect on the filling capacity, as this results in a faster energy / heat and Mass transfer between the gas phase in the dryer and the tobacco particles results, the again of great importance for the success of drying in relation to the Fillability is.

The invention achieves this additional improvement of the energy / heat and Substance exchange through an overpressure operated (pre-) conditioning, so a Conditioning at an absolute pressure of more than 1 bar. This is the continuously falling down tobacco stream in a pressure difference-resistant designed Chamber pressurized with steam, so that in the chamber a temperature and a Adjust the pressure according to the vapor pressure line of the saturated steam.

It is even possible to supply the chamber superheated steam and thus Temperatures in the chamber above the corresponding equilibrium pressure to achieve.

With such pretreatment, tobacco can maintain pressure while maintaining pressure 10 bar absolute in the interior of the chamber to 180 ° C preheated. It is the Preheating associated with simultaneous humidification. Because of this process When condensation is initiated, the temperature and humidity can quickly increase Equilibrium conditions are set.

The preconditioned at overpressure tobacco is directly, ie without intermediate storage, from the preconditioning chamber is introduced into the hot air flow of the dryer and forces the tobacco, depending on the prevailing pressure and temperature in the dryer to assume the corresponding equilibrium temperature of the water. This means, that exploiting the heat energy stored in the tobacco evaporation with Cooling to the so-called cooling limit temperature takes place at ambient pressure between about 40 ° C and 98 ° C, depending on the steam content and the Temperature of the atmosphere in the dryer. If you use a dryer at higher Press, higher cooling limit temperatures can be achieved.

It is thus possible, without convective heat exchange, so the exchange of Energy between drying gas and tobacco particles in forced motion systems, To design evaporation processes based on the presence of thermodynamic Imbalances are based.

This type of dehumidification in the dryer is characterized by extremely high Evaporation rates and results in an additional Füllfähigkeitsgewinn compared to conditioning in open, atmospheric systems such as e.g. Drum or steam tunnel.

In a preferred embodiment, the water vapor is introduced through annular nozzles in the Chamber fed, which is flush with the inner surface of the chamber are to exclude stumbling edges that could hinder the passage of tobacco.

Although the discharge direction of the nozzles in principle horizontally or even upwards directed against the tobacco stream is, according to a preferred embodiment the outflow direction of the nozzle inclined downward to the conveying / flying movement of the To support tobacco and thereby accelerate the free fall and finally the To increase process speed.

The steam can be fed into the chamber at any angle, such as for example also tangential. Preferably, however, it extends at the angle of 90 ° to the circumferential direction of the chamber wall to the highest possible impact achieve.

So that a condensation of the water vapor on the inner wall of the pressure vessel is avoided, the container should be provided with a heating mantle, in the likewise Steam at a slightly higher temperature than the steam temperature of the (Ring) nozzle vapor temperature is fed.

The chamber should extend downwards in the shape of a truncated cone, because if so Risks of constipation can be largely excluded.

Care should be taken to ensure that the tobacco falls through the chamber without jamming, because the otherwise often used damming to generate a residence time in this species the process control is not necessary, since the equilibrium temperature through the Condensation sets very fast.

To prevent any unwanted damming of the tobacco in the pressure chamber avoid, the discharge lock should be operated with slightly higher delivery volumes be considered the entry gate. This can, for example, via the sluice speed and / or a larger chamber volume of the lock chamber can be achieved.

After passing through the pressure chamber, the preheated and moistened, so preconditioned tobacco supplied to a dryer, including the known conventional dryer can be used such as Drum dryer or fluidized bed dryer. By the slower in these variants however, the drying process does not become as full as in use a Luftstromtrockners increased, which is thus preferred.

The exiting from the lower rotary feeder, preconditioned tobacco is thus of entrained in the hot gas flow of such a Luftstromtrockners and by lingering dried in this dryer section to the initial nominal moisture.

This drying of the tobacco is in the first stage by the rapid evaporation marked until reaching the cooling limit temperature; while the Evaporative energy applied solely by the tobacco particles themselves.

In the second section, however, the tobacco is by convective fabric and Heat exchange dehumidified or dried. This second drying process is slower than the evaporation and therefore contributes less to the increase in percentage Fillability at.

Even if, however, with the less favorable embodiments of dryers, namely drum dryers or fluidized bed dryers, works by the above described evaporation / drying operations higher Füllfähigkeiten than in the conventional combination preheating drum / steam tunnel with drum / fluidized bed dryer reached.

As already indicated above, the use of "pressure-difference-resistant Rotary valves "important, so rotary valves, despite the not too avoiding leaks due to sealing problems on the one hand and the vapor, on the other hand, on the other chambers of the rotary valve on the other hand, a largely constant absolute pressure inside the chamber and thus one constant pressure difference between the atmospheric pressure outside the chamber and maintained the internal pressure of the chamber. Suitable, pressure difference resistant Rotary valves are offered on the market.

Figur 1

einen vertikalen Schnitt durch eine erste Ausführungsform einer Vorrichtung zur (Vor-)Konditionierung von zerkleinerten Tabakmaterialien,

Figur 2

einen Schnitt längs der Linie A-A von Figur 1,

Figur 3

einen vertikalen Schnitt durch eine zweite Ausführungsform einer Vorrichtung zur (Vor-)Konditionierung von zerkleinerten Tabakmaterialien,

Figur 4

einen Schnitt längs der Linie A-A von Figur 3, und

Figur 5

ein Diagramm zur Erläuterung des Verfahrensablaufs.

The invention will be explained below with reference to embodiments with reference to the accompanying schematic drawings. Show it:

FIG. 1

a vertical section through a first embodiment of an apparatus for (pre) conditioning of shredded tobacco materials,

FIG. 2

a section along the line AA of Figure 1,

FIG. 3

a vertical section through a second embodiment of an apparatus for (pre) conditioning of shredded tobacco materials,

FIG. 4

a section along the line AA of Figure 3, and

FIG. 5

a diagram for explaining the procedure.

Figure 1 shows a generally indicated by the 'reference numeral 10 Expansion device with a device for preconditioning the crushed Tobacco materials and a subsequent air flow dryer 5, which under the Preconditioning device 12 is arranged.

The substantially vertically arranged Vorkonditioniervorrichtung 12 are about suitable conveying elements, for example vibrating conveyor troughs, cut tobacco particles (Lamina) supplied and via an upper, differential pressure fixed feeder 1 in the pressure-resistant chamber 3 of the device 12 is fed, in the tobacco particles freely after fall down. The chamber 3 widens conically vertically down to a damming to exclude the tobacco particles.

Approximately at the middle level of the chamber 3 annular nozzles 2 (see also Figure 2) are flush arranged with the inner circumferential surface of the chamber 3 to Stolperkanten that the Passing of the tobacco could hinder, exclude.

In the illustrated embodiment, the outflow direction of the annular nozzles 2 is after tilted down to support the conveying / direction of the tobacco. The Outflow of the annular nozzles 2 can in principle but also horizontally or even directed upwards against the tobacco stream.

The tobacco particles fall freely in the truncated cone-like chamber 3 and become via a lower, also differential pressure fixed feeder 4 directly into the horizontal range of a Luftstromtrockners 5 introduced.

As an alternative to the embodiment shown can also be a vertical Stromdrocknungsstrecke be used.

In order to avoid damming the tobacco in the chamber 3, the lower, as Austragsschleuse serving rotary valve 4 with a slightly higher flow operated as the upper entry lock 1; this can be done via the Sluice speed and / or a larger volume of the individual chambers of this Lock can be achieved, as can be seen in Figure 1.

As can be seen in Figure 2, the steam in an annular chamber in the wall of the Chamber 3 introduced, from which the ring nozzles 2 are fed, the radially downward directed into the interior of the chamber.

Even before the beginning of the supply of tobacco particles to the chamber, the interior of the Chamber 3 under pressure, measured absolutely, set by saturated steam through the Ring nozzles 2 is supplied. This allows a pressure in the interior of the chamber 3 build up, which depends only on the temperature of the introduced saturated steam.

Due to the two pressure difference fixed rotary valves 1, 4, this pressure maintained during ongoing, continuous operation, so that in the Comparison with the conventional methods extremely high dryer inlet temperatures and humidify the tobacco.

To a condensation of the water vapor on the inner wall of the chamber 3 to avoid, designed as a pressure vessel chamber 3 with a heating mantle. 6 be provided, as can be seen in Figure 3 and 4. In. the heating jacket 6 is down Steam at a slightly higher temperature than the temperature of the ring via the nozzles 2 sprayed steam supplied while this steam from the top of the heating mantle. 6 is deducted.

After passing through the preconditioning at overpressure and thus at extremely high Temperatures fall the preheated and moistened tobacco particles through the lower Rotary valve 4 down in the air flow dryer 5, where they are from the Hot gas stream entrained and by staying in the dryer on the Discharge nominal moisture be dried.

The drying of the tobacco is in the first stage by the rapid evaporation up marked to reach the cooling limit temperature; while the Evaporative energy applied solely by the tobacco particles themselves.

In the second section, the tobacco is transformed by convective heat and mass transfer dehydrated or dried.

Figure 5 shows a diagram of the conditioning of tobacco particles, the assuming a thermal equilibrium with an inlet temperature of. 20 ° C in a saturated steam atmosphere in the pressure chamber 3 are introduced.

The line marked with triangles indicates the change in the moisture content of the Tobacco particles with an input moisture of 20% and the line marked with squares the change in the moisture content of the tobacco particles with an initial moisture content of 18% at.

As can be seen, the moisture content of the tobacco particles increases after conditioning, Expressed in percent, in the range of a saturated steam temperature of 100 ° C to 160 ° C. linear, so that for example at 'a saturated steam temperature of 160 ° C the Tobacco particles with the input moisture of 18%, the Vorkonditioniervorrichtung with a Leave starting moisture of about 30.25%.

The following is the achievable increase in fillability by way of example be explained that the Druckvorkonditionierung with the device of Figure 3 for Increase of tobacco temperature and tobacco moisture and subsequent Air drying with preconditioning with water and steam at normal Air pressure compares.

This cut tobacco was after cutting with an average moisture of 18% in a tobacco mass flow of 200 kg / h, based on the average moisture of 18%, cold promoted by a conditioning drum (without conditioning) and then at a vapor pressure of 5 bar through the apparatus of Figure 3 driven with superheated steam to 5 bar (> 152 ° C) was preheated. To make moist To avoid nests, care must be taken that as little condensate as possible the interior of the chamber 3 passes.

The falling down in the chamber 3 tobacco is by the inclusion of condensing vapor brought to equilibrium temperature, which at about 152 ° C. lies. This results in a moisture absorption to about 27% by mass. The fall time when crossing a distance of about 1 m is only about 0.5 s.

The so conditioned, so heated and humidified tobacco is in the Air flow dryer 5 dried to a discharge moisture content of about 13% by mass.

For comparison with this procedure according to the invention, the Schnitttabak of 18% moisture in a conventional conditioning drum with the addition of steam and Water at normal ambient pressure to 27% moistened, to about 60 ° C preheated and then in an amount of 200 kg / h. through the device Figure 3 - without further conditioning - promoted in the air flow dryer 5.

Comparing the filling capabilities of the tobacco from both experiments at the outlet of the Luftstromtrockners 5 with each other, then results in the pressure-conditioned tobacco a Fillability increase of 5.9% over the comparative sample, the one appropriate conditioning at ambient pressure in the conditioning drum has gone through.

The fillability results were corrected to 12 mass% humidity to obtain an accurate Comparability.

Corresponding tests were carried out with different vapor pressures in the device performed according to Figure 3, the results obtained, expressed as Fillability gains in percent, as well as the associated process parameters in the following table are summarized.

As a comparative sample to the respective pressure conditioning, as described above, 18% wet cut tobacco in a conditioning drum was conditioned under ambient pressure with steam and water to 60 ° C tobacco temperature and the corresponding tobacco moisture (see the corresponding moisture of the pressure conditioning) to determine the fill capacity increase. Pressure in device [bar] Humidity ex device [mass%] Equilibrium temperature [° C] Fillability increase in [%] 2 24.1 120 3.1 3 24.9 134 3.9 4 26.2 144 4.5 5 26.5 152 5.9 6 27.0 159 6.6 7 27.4 165 7.1

As you can see, the equilibrium temperature is expected to increase with the Pressure in the chamber and in turn leads to a corresponding proportional Füllfähigkeitszuwachs.

This series of tests may vary depending on the quality of the rotary valves with respect to pressure and Temperature to be continued in the direction of increasing pressures / temperatures: it is then with correspondingly higher equilibrium temperatures and increases in fillability expected.

Claims (14)

1. A method for conditioning comminuted tobacco material by heating and moistening with water vapour, wherein:

   a) said comminuted tobacco material free-falls down through a chamber operating in a continuous operation; and

   b) is treated during said free-fall with water vapour via nozzles,
      characterised in that

   c) a hyperbaric pressure, in particular an absolute pressure of more than 1 bar, is maintained in said chamber (3).
2. The method as set forth in claim 1, characterised in that an absolute pressure of 2 to 10 bars is maintained in said chamber (3).
3. The method as set forth in any one of claims 1 or 2, characterised in that saturated vapour is introduced into said chamber (3) through nozzles (2).
4. The method as set forth in any one of claims 1 to 3, characterised in that saturated vapour or superheated vapour with a temperature in the range of 100°C to 200°C is introduced into said chamber (3).
5. A device for conditioning comminuted tobacco material by heating and moistening with water vapour, comprising:

   a) a chamber in which said comminuted tobacco material free-falls downwards;

   b) a cellular wheel sluice at each of the upper inlet and the lower outlet of said chamber; and

   c) nozzles for treating said free-falling, comminuted tobacco material with water vapour;
      characterised in that:

   d) both cellular wheel sluices (1, 4) are formed as pressure differential proof sluices,

   e) such that a hyperbaric pressure of in particular more than 1 bar is maintained in said chamber (3).
6. The device as set forth in claim 5, characterised in that said nozzles (2) are formed as ring nozzles.
7. The device as set forth in any one of claims 5 or 6, characterised in that said ring nozzles (2) are arranged flush with the inner surface of said chamber (3).
8. The device as set forth in any one of claims 5 to 7, characterised in that the discharge direction of said nozzles (2) is inclined downwards.
9. The device as set forth in any one of claims 5 to 8, characterised in that said discharge direction of said nozzles (2), seen in a horizontal plane, extends at an angle of about 90° to the circumferential direction of the wall of said chamber (3).
10. The device as set forth in any one of claims 5 to 9, characterised in that said chamber (3) is provided with a heating jacket (6).
11. The device as set forth in claim 10, characterised in that said heating jacket (6) is heated using vapour.
12. The device as set forth in any one of claims 5 to 11, characterised in that said chamber (3) expands in an approximately tapered manner downwards.
13. The device as set forth in any one of claims 5 to 12, characterised in that said lower cellular wheel sluice (4), formed as a discharge sluice, has a slightly higher conveying volume than the upper cellular wheel sluice (1), formed as a feed sluice.
14. The device as set forth in any one of claims 5 to 13, characterised in that an airflow dryer (5) is connected to said lower cellular wheel sluice (4).

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