TOBACCO EXPANSION SYSTEM (TES)

Description

[0001] The present invention relates to an apparatus for increasing specific volume (also known as puffing) and moisture content of shredded tobacco material which improve the performance of the dryer. In particular, while the apparatus causes to enhance filling capacity of tobacco or tobacco-related materials and serve to improve the performance of the existing dryer in the process.

[0002] Tobacco-related materials refer to the tobacco stem. Tobacco "stem' as used herein includes stems and veins, which are already separated from tobacco leaf laminae of tobacco leaves. Filling capacity is defined as the efficiency of tobacco materials/blend to produce a standard firm cigarette rod. Higher filling capacity leads to use of less tobacco material (weight basis) for a cigarette rod. Expansion ratio and filling capacity are directly proportional.

[0003] There are two main reasons to obtain expanded stem in simple terms; taste and economic concerns. Due to biochemical structure, stem leaves an inconvenient taste when smoking a cigarette. To get out their unpleasant taste and odor, stem must be expanded. Approximately, depending on tobacco types, 30% of its weight of tobacco leaf is a stem. This ratio is too big to be a waste. Hence, utilizing stem in a cigarette making process becomes economically necessary.

[0004] A decrease in filling power starts with curing. Dramatic reduction in moisture content of tobacco material causes water-loss shrinkage. This shrinkage has a negative influence on the volume of tobacco (so filling capacity). Cutting, shredding or flattening (for stem) treatments also decrease filling capacity furthermore. Consequently, tobacco materials, especially stem, specific volume has to increase due to all above mentioned reasons.

[0005] Various techniques have been proposed to obtain expanded tobacco. They can be classified into two main techniques that take part in industry literature; physical and chemical techniques. Physical techniques are based on a phase change of impregnant. They include solid to gaseous change in phase, liquid to gaseous change in phase and dissolving in gaseous change in phase. Chemical methods are based on generating gas by thermal decomposition or exothermic reaction. They include solid to gaseous thermal decomposition, liquid to gaseous thermal decomposition, liquid to gaseous exothermic reaction.

[0006] Physical methods are accepted widely in industry because of their cost-effective and simple implementation in comparison to the chemical methods. Impregnation of tobacco with substances that extract from tobacco after expansion operation by creating pressure and/or temperature difference underlies physical methods. The impregnant may be solid, liquid or gas but generally gaseous impregnates are used. The most common impregnates which are utilized in this technique are steam, air, water, organic volatile liquids. The main underlying logic is to generate and/or expand a gas in the cell of tobacco materials. With liquid impregnant, gas is generated by phase change. In this technique, altered temperature and pressure process parameters are applied.

[0007] U.S. Pat. No. 4.523.598 discloses a method for expanding and drying of tobacco material. Tobacco material is sucked by free jet and accelerated with steam flow. The lower pressure prevailing in the core of the released jet or of the nozzle causes expansion of the tobacco material simultaneously with heat exchange and mass transfer.

[0008] U.S. Pat. No. 6.397.851 proposes cost-effectiveness in producing smoking articles. According to the invention, material continuously passes through a zone of elevated pressure, followed by a zone reduced pressure before ending up in a zone atmospheric pressure. It is claimed that increases in the filling capacity has not been achievable up until now.

[0009] U.S. Pat. No. 4.513.758 proposes simple and inexpensive method of expanding of the tobacco particle. The method includes the steps of introducing moist tobacco particles into a preliminary chamber and then second chamber, which is next to each other. Tobacco is transported from the first portion to second portion via a high-speed stream of gaseous fluid. The Second portion's area is smaller than that of the first portion.

[0010] U.S. Pat. No. 4.407.306 presents a method for treating cut tobacco to expand. Tobacco is inserted into venturi section and, during its rapid transport by the stream in the venturi section and the subsequent section, is expanded. Speed of tobacco travels from its entrance into the conduit until its discharge is such that the tobacco never reaches the speed of the fluid.

[0011] U.S Pat. No. 4.211.243 discloses a process for expanded tobacco stems, which comprises heating under a pressurized atmosphere in the presence of superheated steam tobacco stems. After the process, stems have an excellent smoking taste and a low apparent density.

[0012] U.S. Pat. No. 4.235.249 A discloses a method and apparatus for producing expanded tobacco from whole tobacco stems. Whole tobacco stems are converted to expanded tobacco particles by opening the cellular structure of the stems and moisturizing the stems by the simultaneous application of water and steam. The stems, at a first induced moisture content of from 20 to 40% are then subjected to an equilibration step where the moisture content of the stem is uniformly distributed within the stems. The equilibrated stems are thereafter moisturized to a second induced moisture content by first an application of water and thereafter the simultaneous application of water and steam. At the second induced moisture content of from 30 to 60% the stems are cut into a plurality of particles that are thereafter expanded and dried to a final moisture content of from 13 to 25%.

[0013] GB Pat. No. 2.155.302 A discloses a process for expanding tobacco leaves and apparatus therefor. Tobacco stems are expanded in an expanding tube maintained at predetermined temperature by a water bath . This tube is in connection with a delivery tube from a supply source via a connection tube, forming a tubular system which is wholly hermetically sealed from the outside atmosphere. A high pressure gas is jelled from jetting nozzle disposed within the connection tube section and at once introduced into said expanding tube by passing through a passage (A) of venturi type, where by the cut tobacco stems are sucked from the source through the delivery tube and into said expanding tube by the suction power generated, as if they were injected thereinto accompanying the high pressure gas.

[0014] EP 0 484 899 A1 discloses a method and system for expanding tobacco. Steam or high-temperature gas containing steam is flown through a gas-flow drying pipe . Tobacco is fed from a feed port into the high-temperature gas flowing through the gas-flow drying pipe, and heated and expanded while it is flown together with the gas. Water vapor or water is injected into the high-temperature gas flow from injection nozzles at the positions downstream from the feed port to change the gas temperature. Thereby, the heat quantity given to the tobacco from the high-temperature gas is controlled to prevent the tobacco quality from degrading.

[0015] In this patent, with the proposed apparatus being very compatible for industrial applications, it is expected to reach satisfactory expansion rate and higher throughput with a reasonable capital and operational expenses.

[0016] The aim of the present apparatus is to expand (increasing filling capacity) tobacco stem more effectively. Method covers the reoriented steam jet flows and the moist tobacco stem introduced into it. Any volatile fluid or solid have not been used. Even better, the process accomplishes only by steam and/or water mixture.

[0017] The method involves the treatment of the tobacco stem with steam jet streams homogeneously. Material passes through the vertical and horizontal tubes is evenly heated and moistened. Furthermore, the apparatus comprises two narrow passes in order to create pressure difference and to improve the steam application quality. Homogeneous impregnation of steam or/and water mixture into the stem is the key factor to improve process and method quality. In this apparatus, the stem is accelerated twice through the steam jets. Acceleration causes to velocity difference between tobacco and steam/water mixture. Increasing the relative velocity between the steam medium and tobacco, enhances the expansion effect. Further, the method can deliver water (preferably finely atomized warm or cold) with steam.

[0018] When phase change occurs (liquid to gas), fluids' specific volume extremely increase. Likewise, the specific volume of the gaseous increase while the pressure reduces. As specific volume increases, fluid molecules exert pressure (or simply force) to cell membrane and cause expansion permanently.

[0019] To obtain a reduction in pressure, steam is speeded up to the speed of sound by the ultrasonic nozzles (4) . Venturi shaped tube allows to transport the high speed steam and tobacco along with from vacuum pressure to atmospheric pressure. Tobacco stem (having moisture at least equals or exceeds 35 percent and at the room temperature) enters to the apparatus from the vertical tube via drop-through airlock (1) . A group of steam nozzles (3) (flat or hollow cone type) are located in the vertical tube. When tobacco stem enters into the upright tube, steam jets (through steam nozzles (3) ) hit the tobacco. Steam is impregnated in stems and increases its moisture and temperature upon impact. This part of the apparatus/method is named as "pre-conditioning part." Furthermore, the conditioned tobacco stem particles are accelerated towards to horizontal tube by the help of the steam nozzles. Horizontal tube (also named as venturi tube (5) ) has the ultrasonic nozzles (4) and the tapered section venturi pipe.

[0020] Ultrasonic nozzles (4) located at the horizontal tube create vacuum. So, due to that vacuum, steam tobacco mixture that exists in pre-conditioning part is sucked into the horizontal tube.

[0021] High rate of heat and mass transfer induces an increase in both product moisture and temperature. Also, followed by flash evaporation of the water present in the tobacco cells as the particles accelerate away from the vertical tube into the horizontal tube. Instantaneous pressure drop of fluid in venturi tube (5) induces further expansion of tobacco.

[0022] The Tobacco stem is transferred to discharge section, after the treatment of tobacco stem with steam in vertical and horizontal tube. A tobacco stem-steam separator (6) , specifically, a centrifugal separator (6), separates steam and tobacco from each other. The separated tobacco is fed into dryer inlet and the waste steam is thrown out into scrubber.

[0023] The apparatus will now be explained in more detail by means of an exemplary embodiment of the device according to the invention illustrated in the figure, in which:
Fig. 1 shows a cross section view of the front side of the device according to the apparatus;

[0024] In the figs. 1, reference numbers; (1) an airlock, (2) a pre-conditioning tube, (3) steam nozzles, (4) ultrasonic nozzles (also named as Laval nozzles), (5) a venturi tube, (6) separator, (7)-(7') steam jets pathway, (8) nozzle antechamber, (9) take-up point, (10) neck, (11) exit diffuser, (12) another steam jet's pathway. T denotes tobacco material.

[0025] Fig. 1 is a schematic illustration of an apparatus of the present invention for expanding tobacco material. The shredded tobacco stem, T from after cutter is fed into pre-conditioning tube (2), by an airlock (1) which is workable under high temperature, and differential pressure. Pre-conditioning tube (2) is conical shaped metallic tube and includes steam nozzles (3). At the pre-conditioning tube (2), stem fall freely reaches up to take-up point (9) where steam jets pathway (7-7') intersect with each other, then stem is mixed with steam or steam-water mixture that emerges from steam nozzles (3). Four mutual steam nozzles (3) are positioned at an angle of 10° to 70° with respect to the pre-conditioning tube's (2) axis. Stem heat and moist and accelerate towards to venturi tube (5), by steam jets pathway (7-7'). Main reason of heating and moistening is impregnation of steam into stem. The mass flow rate of steam jets pathway (7-7') set simply (at 2 bar pre-pressure, approx. 120°C pre-temperature) relative to desired expansion ratio. Operational ratio is in the range of 0 to 0.1kg steam flow per kg tobacco.

[0026] The moistened and heated stem and the steam mixture transfer perpendicularly to the horizontal located venturi tube (5), after passing through a neck (10) . Venturi tube (5) is conical shaped metallic tube. Another group of steam nozzles (3) (ultrasonic nozzles (4) ) create slightly vacuum at downside of the neck (10) so that tobacco steam mixture can penetrate high-velocity another steam jets pathway (12) that emerge from ultrasonic nozzles (4) . At the out of the ultrasonic nozzles (4), another steam jets pathway (12) reach to 800 m/s velocity and while the velocity of tobacco-containing jets is approximately 150 m/s in the venturi tube (5). The mass flow rate of another steam jets pathway (12) set simply (up to 6 bar pre-pressure, approx. 150°C pre-temperature) relative to desired thrust force. Operational ratio is in the range of 0 to 0.3 kg steam flow per kg tobacco. Additional heat and mass transfer is occurred in venturi tube (5) by another steam jets pathway (12), so the stem gets homogeneously warmer and moistened pretty well. Since the tapered cross-section of the venturi tube (5), pressure is dropped throughout the tube. While stem passes lower pressure zone (vacuum zone), heated moisture in the stem cannot be as a liquid phase, so moisture evaporates to gaseous phase. Furthermore, in the vacuum zone, the specific volume of noncondensed vapor in stem will increase. As a result of increasing volume, tobacco cell membrane harms permanently, and expansion happens. Further expansion occurs in the dryer that is located after the apparatus.

[0027] After mixture passes through the venturi tube (5), it is transported into separator (6) by the help of exit diffuser (11) . Exit diffuser (11) is a conical shaped metallic tube. As mixture travels along in exit diffuser (11), its velocity is reduced thereby and the stem is not damaged. In the end, the tobacco stem and the steam are separated each other by separator (6).

Claims

1. A method for increasing the specific volume of tobacco stem particles by steam and a steam and water mixture, said method comprising the following steps:

- introducing tobacco stem into the pre-conditioning tube (2) prior to an acceleration zone in a first part of an apparatus;

- further feeding said tobacco stem into a venturi tube (5) in a second part of said apparatus, the cross-sectional area of said venturi tube (5) being less than that in the first conditioning part; characterized in that:

- both said apparatus parts have adjustable mass flow ratio steam jets (7,7',12);

- said tobacco stem is accelerated twice by jet flows, and

- said apparatus comprises two narrow cross sectional pipes (10) to improve treatment quality.

2. The method of claim 1 wherein said jet flows can be superheated or saturated steam.

3. The method of claim 1 wherein said jet flows can be mixed with hot or cold water.

4. The method of claim 1 wherein velocity of said jet flows at least one of them equals or greater than speed of sound.

5. The method as mentioned in claim 1, consists of two conical pipes, they connect each other perpendicularly.

6. The method of claim 1 wherein said steam pressure is between 2 bars to 6 bars.

7. The method as claimed in claim 1, wherein said velocity of jet flows containing said tobacco stem is between 20m/s to 200 m/s.

8. The method of claim 1 wherein total mass flow ratio of steam to the tobacco stem is in a range of 0.1 to 0.5.

Ansprüche

1. Verfahren zur Erhöhung des spezifischen Volumens von Tabakstängelpartikeln durch Dampf und ein Dampf-Wasser-Gemisch, wobei das Verfahren die folgenden Schritte umfasst:

- Einführen von Tabakstängeln in das Vorkonditionierungsrohr (2) vor einer Beschleunigungszone in einem ersten Teil einer Vorrichtung;

- Weiteres Einführen des Tabakstängels in ein Venturi-Rohr (5) in einem zweiten Teil der Vorrichtung, wobei die Querschnittsfläche des Venturi-Rohrs (5) kleiner ist als die im ersten Konditionierungsteil;

dadurch gekennzeichnet, dass:

- beide Geräteteile Dampfdüsen (7, 7', 12) mit einstellbarem Massenstromverhältnis aufweisen;

- der Tabakstängel zweimal durch Düsenströme beschleunigt wird, und

- die Vorrichtung zwei Rohre (10) mit engem Querschnitt umfasst, um die Behandlungsqualität zu verbessern.

2. Verfahren nach Anspruch 1, wobei es sich bei den Strahlströmen um überhitzten oder gesättigten Dampf handeln kann.

3. Verfahren nach Anspruch 1, wobei die Strahlströme mit heißem oder kaltem Wasser gemischt werden können.

4. Verfahren nach Anspruch 1, bei dem die Geschwindigkeit der Strahlströme zumindest einer von ihnen gleich oder größer als die Schallgeschwindigkeit ist.

5. Verfahren nach Anspruch 1, bestehend aus zwei konischen Rohren, die senkrecht miteinander verbunden sind.

6. Verfahren nach Anspruch 1, wobei der Dampfdruck zwischen 2 bar und 6 bar liegt.

7. Verfahren nach Anspruch 1, wobei die Geschwindigkeit der Strahlströme, die den Tabakstamm enthalten, zwischen 20 m/s und 200 m/s liegt.

8. Verfahren nach Anspruch 1, bei dem das Gesamtmassenstromverhältnis von Dampf zu Tabakstängel in einem Bereich von 0,1 bis 0,5 liegt.

Revendications

1. Méthode d'augmentation du volume spécifique des particules de tiges de tabac par la vapeur et un mélange de vapeur et d'eau, comprenant les étapes suivantes :

- l'introduction de la tige de tabac dans le tube de pré-conditionnement (2) avant une zone d'accélération dans une première partie d'un appareil ;

- l'alimentation de ladite tige de tabac dans un tube venturi (5) dans une deuxième partie de l'appareil, la section transversale dudit tube venturi (5) étant inférieure à celle de la première partie de conditionnement ;

caractérisé dans ce domaine :

- les deux parties de l'appareil sont dotées de jets de vapeur à débit massique réglable (7, 7', 12) ;

- ladite tige de tabac est accélérée deux fois par les flux de jet, et

- ledit appareil comprend deux tuyaux à section étroite (10) afin d'améliorer la qualité du traitement.

2. Méthode de la revendication 1 dans laquelle les flux de jet peuvent être de la vapeur surchauffée ou saturée.

3. Méthode de la revendication 1 dans laquelle les jets peuvent être mélangés à de l'eau chaude ou froide.

4. Méthode de la revendication 1, dans laquelle la vitesse de ces flux de jet, au moins l'un d'entre eux, est égale ou supérieure à la vitesse du son.

5. La méthode mentionnée dans la revendication 1 consiste en deux tuyaux coniques, reliés l'un à l'autre perpendiculairement.

6. Méthode de la revendication 1, dans laquelle la pression de la vapeur est comprise entre 2 et 6 bars.

7. Méthode selon la revendication 1, dans laquelle la vitesse des flux de jet contenant la tige de tabac est comprise entre 20 m/s et 200 m/s.

8. Méthode de la revendication 1, dans laquelle le rapport du débit massique total de la vapeur à la tige de tabac est compris entre 0,1 et 0,5.

Drawing