EP0074059B1 - Method of improving the filling capacity of tobacco material - Google Patents

Description

The invention relates to a method for improving the fillability of tobacco material by expanding the moist tobacco material by reducing the pressure and then drying to processing moisture.

From the non-prepublished EP-A-0 074 534 with priority of September 16, 1981, a method of the type mentioned is known, but which works with considerably longer expansion times.

The invention is directed to a method of the type mentioned in the introduction, in which tobacco material in the moist state is subjected to a pressure reduction with a simultaneous strong temperature increase within an extremely short period of time. The sudden evaporation of the liquid contained, in particular water and / or other easily evaporable harmless organic solvents, leads to an improvement in the fillability of the tobacco material by 30 to 100% without the tobacco cell structure being appreciably destroyed. Despite the high expansion result, the structure is retained even when the tobacco material is further processed. Tobacco material in the sense of the invention is to be understood in particular as cut rib and / or leaf material, and also reconstituted tobacco.

The above object is achieved according to the invention in that the tobacco material with a moisture content of 18 to 80% by weight (wet basis) is conveyed at temperatures between -80 ° C. and 100 ° C. to the base of a free jet or a nozzle and by means of a Temperature between 50 and 1000 ° C and a vapor content between 0 and 100 wt .-% gaseous medium is accelerated, the speed of the gaseous medium at the base of the free jet or in the narrowest cross section of the nozzle at least 20 m / s and the duration of the expansion process ¹ / _10th bis _^1/1000 s.

The method of the invention offers the particular advantage that the expansion system can have a simple apparatus construction. In view of the low mass ratio of transport gas / tobacco material, the energy requirement is low. Furthermore, the tobacco expansion can be carried out in a continuous procedure with the method of the invention.

Following expansion, the tobacco material is dried to processing moisture in the usual way. Drying is normally carried out to a moisture content of 10 to 16% (wet basis). However, it is also possible to dry the tobacco material to a significantly lower moisture content, e.g. B. up to 2% (wet basis). This ensures a particularly permanent fixation of the expanded structure. However, it is necessary to moisten the strongly dried tobacco material thus obtained to a moisture content of 10 to 16% (wet basis) before further processing.

Air, water vapor, air / water vapor mixtures with a water vapor content of 2 to 80% by weight of inert gases, e.g. Nitrogen or carbon dioxide, hydrocarbon or mixtures thereof can be used. Water vapor is preferred, which, depending on the process control, can also be overheated.

According to the invention, the tobacco material is brought into a free jet formed by the gaseous medium, the tobacco material either being sucked in through the free jet itself or at the essentially narrowest point of a suitable nozzle, e.g. of a jet pump or similar type. The free jet can also be limited by a fixed wall. Due to the suction effect of the generally turbulent free jet or nozzle, the tobacco material is drawn into the core of the free jet or nozzle and accelerated to the flow rate of the gaseous medium. The lower pressure prevailing in the core of the free jet or nozzle causes the tobacco material to expand while at the same time exchanging heat and material. With increasing diameter of the free jet or the nozzle, the flow rate of the gaseous medium decreases and, correspondingly, the speed of the tobacco material. B. comes with a horizontal arrangement of the free jet or the nozzle for the separation of gaseous medium and tobacco material. The tobacco material is then dried in the usual way. However, the expansion device can also be connected to a dryer to form a unit.

The specified flow velocity of the gaseous medium of at least 20 m / s essentially relates to the jet foot; it is preferably at least 80 m / s.

While process variants of the invention in which the tobacco material is introduced into the gaseous medium which already has a flow rate of at least 20 m / s and are thus accelerated to the flow rate of the medium have previously been addressed, it is also possible to combine the tobacco material, in particular tobacco rib cut accelerate with the gaseous medium. Preferably, the tobacco material is brought together with the gaseous medium initially at a rate of 6 to 50 m / s, s accelerated in an acceleration zone of an expansion reactor within at most _^1/10 to a velocity of at least 50 m / s, constant through a zone speed transported and then decelerated in a deceleration zone of the expansion reactor, the residence time of the tobacco material is s in the zone at a constant speed between ¹ / _100th, and ¹ / _1000th The ratio of the speed of the gaseous medium or the tobacco material in front of the acceleration zone to the maximum speed in the same is at least 1: 3, preferably at least 1: 6. The acceleration of the gas shaped medium or the tobacco material is preferably carried out in a venturi-type nozzle arranged in the expansion reactor or in another suitable nozzle arrangement.

In general, it applies to all process variants that the greater the speed and temperature of the gaseous medium, the better the expansion result achieved.

The gaseous medium has a temperature of 50 to 1000 ° C, in particular at least 100 ° C. Since the temperature of the gaseous medium is generally higher than that of the tobacco material, some heat exchange takes place, but this can be neglected in terms of drying due to the relatively short time in which the tobacco material and the transport gas come into contact.

Although the arrangement of a venturi nozzle at the end of a drying section for tobacco material is known from DE-A 2 637 124, in particular FIG. 3, tobacco expansion cannot occur here either, since the venturi nozzle mentioned is located at one point of the device is arranged where there is already dried tobacco; the tobacco dried in this way no longer has the elasticity required for expansion. In contrast, in the method of the invention, the tobacco traverses the expansion path in a moist state and is only then dried.

• Fig. 1 ein Fliessschema für eine bevorzugte Verfahrensform;
• Fig. 2 eine Düsenanordnung in schematischer Darstellung zur Verwendung in dem Verfahren gemäss Fig. 1;
• Fig. 3 ein Fliessschema für eine andere Ausführungsform des Verfahrens der Erfindung;
• Fig. 4 eine Expansionssektion zur Verwendung in dem Verfahren gemäss Fig. 3;
• Fig. 5 eine unabhängig vom Trockner arbeitende Expansionssektion.

The method of the invention is explained below with reference to the drawings and exemplary embodiments. Show it:

• 1 shows a flow diagram for a preferred process form;
• FIG. 2 shows a nozzle arrangement in a schematic representation for use in the method according to FIG. 1;
• Fig. 3 is a flow diagram for another embodiment of the method of the invention;
• FIG. 4 shows an expansion section for use in the method according to FIG. 3;
• 5 shows an expansion section working independently of the dryer.

1, an apparatus for carrying out the method of the invention comprises a conveyor device 1 for the introduction of tobacco rib cut 2 into the feed part of an (horizontally or vertically arranged) expansion reactor 3. The expansion reactor comprises a venturi-type nozzle used or another suitable nozzle arrangement with an acceleration zone 4, a zone 5 of constant speed and a deceleration zone 6. A conventional current dryer 7 with a connected separator 8 is connected to the expansion reactor. The system can be self-contained; the sealing to the environment is carried out on the feed side by a rotary valve (not shown) and on the take-off side by a rotary valve 9, through which the expanded tobacco is removed from the system.

The transport gas is supplied via valves or flaps 10 and 11, e.g. B. saturated steam at 10 and fresh air at 11; the exhaust gas is removed via a flap 12. The nozzle arrangement (4, 5, 6) can also be seen in an enlarged view from FIG. 2. The following general process parameters apply to the process of the invention:

Tobacco material with a moisture content of 18 to 80, in particular 30 to 80, preferably 40 to 80% (wet basis) is conveyed through the expansion nozzle at temperatures between -80 ° C and +100 ° C together with a hot gas flow. The hot gas stream has temperatures between 50 and 1000 ° C; its steam content can be between 0 and 100% by weight. The hot gas flow velocity in front of the acceleration zone is between 6 and 50 m / s: it increases in the narrowest nozzle cross-section to at least 50 m / s. The hot gas mass flow is 5 to 36 times larger than the tobacco mass flow. The sudden drop in pressure in the nozzle leads to so-called flash evaporation from the single fiber. The extremely quickly generated steam inflates the fibers. The energy for the evaporation of the water is essentially obtained from the tobacco fiber itself, ie the temperature of the tobacco material drops only slightly in the expansion nozzle. The expansion process takes less than 0.1 s, in particular ¹ / _100th bis _^1/1000 s.

The device for carrying out the method of the invention according to FIG. 3 comprises, in addition to the conveying device 1 for the tobacco material 2, a feed part 13 of a horizontally arranged expansion section 14, which in the manner shown in FIG. 4 consists of a tube 15 and longitudinal slots 16. The longitudinal slots form the base points for a free jet 17. In the embodiment shown here, the expansion device 15 is integrated in the inlet of a conventional current dryer 18, so that the free jet 17 conveys the tobacco material 2 directly into the current dryer 18. Baffles provided to improve the flow guidance are not shown. The tobacco material is withdrawn from the current dryer via the separator 8 and the rotary valve 9.

The system can be self-contained, the sealing to the environment is carried out on the feed side by a rotary valve (not shown) and on the take-off side by rotary valve 9, through which the expanded material is removed from the system.

The gaseous medium is supplied via a valve 19; the valve 10 and the flaps 11 and 12 are used to adjust the dryer.

5 shows an expansion device decoupled from drying. The tobacco material entering the system via a cellular wheel sluice 20 hits the jet 17 essentially perpendicularly, is accelerated and expanded by the jet 17, and is led away essentially horizontally to a dryer device (not shown) of any design. Depending on the design of the expansion device, there may be overpressure or underpressure in the system.

The following general process parameters apply to the process of the invention according to FIG. 3:

Tobacco material with a moisture content of 18 to 80, especially 30 to 80% (wet basis) is conveyed to the base of the free jet or a nozzle at temperatures between 80 ° and 100 ° C, accelerated by the gaseous medium and then decelerated and passed to a dryer . The propellant gas has temperatures between 50 and 1000 ° C; its steam content can be between 0 and 100% by weight. The propellant gas velocity in the narrowest cross section of the nozzle or at the base of the free jet is at least 20 m / s. An upper limit of the flow rate results solely from a practical point of view. B. be up to 900 m / s. The sudden drop in pressure in the free jet or in the nozzle with superimposed heat supply leads to so-called flash evaporation from the single fiber. The expansion process takes less than 0.5 s, in particular ¹ / _10th bis _^1/1000 s.

The invention is explained in more detail below on the basis of exemplary embodiments.

example 1

A pilot plant on a pilot plant scale was used to investigate the method of the invention according to FIG. 1. The dimensions of the pilot plant are as follows: Greatest edge length of the

For the test, the pilot plant was set up so that the rib cut could be entered without a lock. The rib section to be treated was moistened with cold water to approx. 45% (wet basis) and conveyed into the entry at ambient temperature (25 ° C). The mass flow of the rib cut was 25 kg / h, the transport gas mass flow was 300 kg / h. The ratio of transport gas to rib cut mass flow is thus 12: 1. The temperature of the transport gas stream at the rib cut entry was 340 ° C.

A transport gas mass flow with a steam content of 85 mass percent was set. A speed of 22 m / s was measured in the cross section immediately behind the tobacco inlet and a speed of 137.5 m / s in the narrowest cross section of the expansion nozzle. Behind the expansion nozzle, the rib cut was dried to 13% in the usual drying section. The discharge was carried out by a cyclone. The expanded rib cut and a rib cut treated for comparison purposes only in a current dryer were conditioned for 72 hours at 60% relative atmospheric humidity and 22 ° C. (according to DIN 10 244). The filling force was measured in the Borgwaldt densimeter (sample weight 10 g, diameter of the measuring cup 60 mm, load 3000 g and 30 s).

The remaining height of the rib cut treated according to the prior art was 14.8 mm; that of the one obtained by the process of the invention was 23.7 mm, in each case at a humidity of 12.6%; determined according to the oven method: 3 h, 80 ° C.

The increase in the filling capacity of the tobacco rib cut treated according to the method of the invention is approximately 60% compared to the comparison product according to this method.

Example 2

The experiment according to Example 1 was repeated with a leaf cut (20% moisture; wet basis). Because of the lower initial moisture, the tobacco mass flow was increased to 80 kg / h and the dryer temperature was reduced to 250 ° C. A filling capacity increase of 30% was obtained.

Example 3

The experiment according to Example 1 was repeated in the pilot plant described there, the steam content of the transport gas mass flow being reduced to 4% by mass. The rib section to be treated was moistened with cold water to approx. 45% (wet basis) and conveyed into the entry at ambient temperature (25 ° C). The mass flow of the rib cut was 25 kg / h; that of the transport gas 300 kg / h. This results in a ratio of transport gas to rib cut mass flow of 12: 1. The temperature of the transport gas mass flow at the rib cut entry was 340 ° C.

Due to the change in density, there is a speed of 15 m / s immediately behind the tobacco inlet and a speed of 93.8 m / s in the narrowest cross section of the expansion nozzle. Behind the expansion nozzle, the rib cut was dried to 13% in a normal drying stretch. A cyclone removes them. The conditioning and measurement was carried out analogously to Example 1. According to the measurement method used, the increase in the filling capacity for the tobacco rib cut treated according to the invention is 30%.

Example 4

A semi-technical system was used to examine the method of the invention according to FIG. 3. The dimensions of the system are as follows:

The experiments given here were carried out with a rib cut. For the test, the pilot plant was set up so that the rib cut could be entered without a lock. The rib cut to be treated was moistened with cold water to approx. 45% (wet basis) and conveyed into the entry at ambient temperature (20 ° C.). The mass flow of the rib cut was 100 kg / h. Saturated steam of 8 bar (t = 170.41 ° C.) was used as the propellant. The motive steam flow was 300 kg / h. The ratio of the rib cut to the motive steam mass flow is therefore 1: 3. Behind the free jet, the rib cut was dried to 15% in the usual drying section with air at a temperature of 3400e. The discharge was carried out by a cyclone. The expanded rib cut and a rib cut treated for comparison purposes in a current dryer (without free jet) were conditioned for 72 hours at 60% relative atmospheric humidity and 22 ° C (according to DIN 10 244). The filling force was measured in the Borgwaldt densimeter (sample weight 10 g, diameter of the measuring cup 60 mm, load 3000 g and 30s).

The remaining height of the rib cut treated according to the prior art was 14.8 mm, that of the one obtained by the method of the invention was 18.59 mm, in each case at a humidity of 12.6%, determined by the oven method: 3 h, 80 ° C. The increase in the filling capacity of the tobacco rib cut treated according to the method of the invention is approximately 25% compared to the comparison product according to this method.

Example 5

The experiment according to Example 4 was repeated in the pilot plant described there, the motive steam mass flow being reduced to 80 kg / h and overheating to 300 ° C. (a larger motive steam mass flow could not be run because of the steam superheater available). The rib cut to be treated was moistened with cold water to approx. 45% (wet basis) and conveyed to the base of the free jet at ambient temperature (25 ° C). The mass flow of the rib cut was 100 kg / h. The ratio of the rib cut to the motive steam mass flow is therefore 1: 0.8. The rib cut was dried behind the free jet in the drying section at a temperature of 340 ° C. to 15%. The discharge was carried out by a cyclone. The conditioning and measurement was carried out analogously to Example 3. According to the measurement method used, the increase in the filling capacity for the tobacco rib cut treated according to the invention is 30%.

Claims (9)

1. A method of improving the filling capacity of tobacco material by expansion of the moist tobacco material by pressure reduction and subsequent drying to manufacturing humidity, characterised in that the tobacco material with a moisture content of from 18 to 80% by weight (wet basis) at temperatures between -80°C and 100°C is conveyed to the base of a free jet or nozzle and is accelerated by means of a gaseous medium having a temperature of between 50 and 1000°C and a vapour content of between 0 and 100% by weight, wherein the velocity of the gaseous medium at the base of the free jet or in the narrowest cross-section of the nozzle is at least 20 m/s and the duration of the expansion process is between ¹/₁₀ and ¹/₁₀₀₀ s.

2. A method according to Claim 1, characterised in that the tobacco material (2) is drawn in by the free jet (17).

3. A method according to Claim 1, characterised in that the tobacco material is introduced at substantially the narrowest point of a nozzle of jet- pump type.

4. A method according to Claim 1, characterised in that the tobacco material is accelerated together with the gaseous medium.

5. A method according to Claim 4, characterised in that the tobacco material (2) together with the gaseous medium is brought to a velocity of between 6 and 50 m/s, is accelerated in an acceleration zone (4) of an expansion reactor within at most ¹/₁₀ s to a velocity of at least 50 m/s, is conveyed through a zone (5) of constant velocity and, subsequently, is retarded in a deceleration zone (6) of the expansion reactor, in particular to the initial velocity, wherein the residence time of the tobacco material in the constant velocity zone (5) is between ¹/₁₀₀ and ¹/₁₀₀₀ s.

6. A method according to Claim 4 or 5, characterised in that the ratio of the velocity of the gaseous medium and/or of the tobacco material upstream of the acceleration zone (4) to the maximum velocity therein is at least 1 : 3, preferably at least 1 : 6.

7. A method according to at least one of Claims 4 to 6, characterised in that the acceleration of the gaseous medium and/or of the tobacco material takes place in a venturi-type nozzle arranged in the expansion reactor.

8. A method according to at least one of Claims 1 to 7, characterised in that the gaseous medium has a temperature of between 50 and 1000°C.

9. A method according to at least one of Claims 1 to 8, characterised in that the gaseous medium is air, water vapour, inert gas, hydrocarbons or a mixture thereof.

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