VIRAG, Otto (Chair-d'Ane 14, Saint-Blaise, CH-2072, CH)
| Claims 1. Method of expanding tobacco material, comprising: providing the tobacco in a substantially hermetically sealable chamber (3, 4, 24, 25, 26, 27) with ambient pressure, wherein a pressure cylinder (12) is in fluid communication with the chamber (3, 4, 24, 25, 26, 27), the pressure cylinder (12) further comprising a piston (14); and moving the piston (14) of the pressure cylinder (12) such that the pressure in the chamber (3, 4, 24, 25, 26, 27) is altered to a pressure different to ambient pressure, wherein the step of providing the tobacco in the substantially hermetically sealable chamber (3, 4, 24, 25, 26, 27) comprises the further steps of: dislocating a first lock (5, 6) of the chamber (3, 4, 24, 25, 26, 27) to create a first opening in the chamber (3, 4, 24, 25, 26, 27), and inserting the tobacco into the chamber (3, 4, 24, 25, 26, 27) through the first opening; and after expanding the tobacco in the chamber, the method further comprises the steps of: dislocating a second lock (7, 8) of the chamber (3, 4, 24, 25, 26, 27) to create a second opening in the chamber, and discharging the expanded tobacco from the chamber (3, 4, 24, 25, 26, 27) through the second opening. 2. Method according to claim 1 , wherein altering the pressure comprises lowering the pressure in the chamber (3, 4, 24, 25, 26, 27) to a pressure below ambient pressure by movement of the piston (14). 3. Method according to claim 1 , comprising increasing the pressure in the chamber (3, 4, 24, 25, 26, 27) to a pressure above ambient pressure by movement of the piston (14), and subsequently lowering the pressure to ambient pressure. 4. Method according to claim 3, wherein the lowering of the pressure to ambient pressure is enabled by opening a valve. 5. Method according to any of the previous claims, comprising the step of injecting a treatment medium to the chamber (3, 4, 24, 25, 26, 27) via an injection valve (16, 17). 6. Method according to claim 5, comprising circulating the treatment medium to flush the chamber by: injecting the treatment medium through the injection valve (16, 17) into the chamber (3, 4, 24, 25, 26, 27); discharging the treatment medium through a purge valve (18, 19) installed in the chamber (3, 4, 24, 25, 26, 27) or cylinder (12) or fluid communication duct (9,10); and feeding the discharged treatment medium to the injection valve (16, 17). 7. Method according to any of the previous claims, wherein several substantially hermetically sealable chambers (3, 4, 24, 25, 26, 27) are provided on a revolving member (2), and the method comprises the steps of: providing the tobacco in one of the chambers (3, 4, 24, 25, 26, 27), which is in a loading position; rotating the revolving member (2); maintaining the tobacco in one of the chambers (3, 4, 24, 25, 26, 27) at the pressure different to ambient pressure, while the revolving member (2) is rotated; and discharging the tobacco from the chamber (3, 4, 24, 25, 26, 27), when the chamber (3, 4, 24, 25, 26, 27) is in a discharging position. 8. Method according to claim 7, comprising pressurizing the substantially hermetically sealable chamber (3, 4, 24, 25, 26, 27) with a separate cylinder provided for each of the substantially hermetically sealable chambers (3, 4, 24, 25, 26, 27). 9. Method according to claim 7, comprising pressurizing the substantially hermetically sealable chamber (3, 4, 24, 25, 26, 27) filled with tobacco in a pressurizing position by a stationary cylinder (12) in communication with the substantially hermetically sealable chamber (3, 4, 24, 25, 26, 27) in the pressurizing position. 10. Method according to any of the previous claims, wherein the cylinder (12) and the chamber (3, 4, 24, 25, 26, 27) are separated by a screen which is permeable for fluids but not for the tobacco. 11. Tobacco expansion apparatus, comprising a substantially hermetically sealable chamber (3, 4, 24, 25, 26, 27), a pressure cylinder (12) in communication with the chamber (3, 4, 24, 25, 26, 27), wherein the pressure cylinder (12) comprises a piston (14) and is adapted to alter the pressure in the chamber (3, 4, 24, 25, 26, 27) to a pressure different from ambient pressure, and locks (5, 6, 7, 8) for opening and closing the substantially hermetically sealable chamber (3, 4, 24, 25, 26, 27), wherein the locks (5, 6, 7, 8) are slidably or pivotably mounted to enable the opening and closing of the chamber (3, 4, 24, 25, 26, 27). 12. Tobacco expansion apparatus according to claim 11 , comprising several substantially hermetically sealable chambers (3, 4, 24, 25, 26, 27), wherein each of the chambers (3, 4, 24, 25, 26, 27) is adapted to be subsequently located in a loading position, where tobacco can be filled in the respective chamber (3, 4, 24, 25, 26, 27), wherein further each of the chambers (3, 4, 24, 25, 26, 27) is adapted to be located in a discharging position, where tobacco can be discharged from the respective chamber (3, 4, 24, 25, 26, 27). 13. Tobacco expansion apparatus according to claim 12, wherein the several substantially hermetically sealable chambers (3, 4, 24, 25, 26, 27) are provided on a revolving member (2), which is adapted to be rotated. |
The present invention relates to a method of expanding tobacco and a tobacco expansion apparatus.
In the prior art, a method of expanding tobacco is known which comprises putting the wet cut tobacco into a flow of a transport medium that travels at a high velocity at an elevated temperature. Typically, the transport medium is air or saturated or superheated steam that expands and dries the tobacco at the same time. In such an expansion apparatus the ratio of the transport medium and the tobacco cannot be freely adjusted since the tobacco is transported by the same medium and the ratio has to be chosen in a manner appropriate to allow transportation and drying of the tobacco. A further disadvantage of the expansion of tobacco using a transport medium is that it requires a relatively large amount of space. Further, a pressurization significantly above or below atmospheric pressure is not possible. An example for such a method known in the prior art can be found in US 5,251 ,649.
Furthermore, a stationery tobacco expansion is known from US 1 ,789,435, wherein tobacco to be treated is placed in a perforated container which is set into a chamber having a steam tight cover. Gas from a compressor is admitted into the chamber. To release the pressure from the chamber a piston valve is instantly unseated. The sudden release of pressure enables that gas trapped under pressure within some of the constituents of the tobacco will expand the tobacco.
However, the aforementioned method requires a relatively complex fluidic system for the build-up and release of pressure, and further cannot be operated with a high throughput.
There is thus a need to provide a tobacco expansion apparatus that requires less space but has a high throughput and high expansion efficiency.
The object of the present invention is to provide a tobacco expansion method and apparatus that requires little space and may expand tobacco with a high throughput rate and a high expansion efficiency.
This is enabled by a method of expanding tobacco, wherein tobacco is provided in a substantially hermetically sealable chamber with ambient pressure. A pressure cylinder is in fluid communication with the chamber. According to the invention the pressure cylinder further comprises a piston. The piston of the pressure cylinder is moved such that the pressure in the chamber is altered to a pressure different from ambient pressure. The feature to alter the pressure to a pressure different from ambient pressure by moving the piston allows to rapidly altering the pressure in the substantially hermetically sealable chamber with respect to the ambient pressure. Thus, in contrast to the prior art of stationary tobacco expansion, where the initial pressure build-up is provided slowly by means of a compressor, the present invention allows to quickly increasing or decreasing the pressure in the chamber. This enables a more efficient processing of the tobacco. Inter alia, the tobacco expands due to a phase change of the water in the tobacco from liquid to gaseous. It is believed that the amount of expansion of the tobacco increases with the speed of the pressure change. The higher the speed of the pressure change, the larger is the volume of the expanded tobacco.
Preferably, the step of providing the tobacco in the substantially hermetically sealable chamber comprises dislocating a first lock of the chamber to create a first opening in the chamber, and then inserting the tobacco into the chamber through the first opening. After expanding the tobacco in the chamber, the method comprises the step of dislocating a second lock of the chamber to create a second opening in the chamber. In a further step the expanded tobacco is discharged from the chamber through that second opening. This enables that tobacco can be fed through the chamber by using the first opening as an inlet opening and the second opening as a discharging opening. Thus, the method can be applied in an automated factory environment with a designated tobacco streaming direction. Therefore, a tobacco expansion method with a high throughput can be implemented.
Preferably, the pressure in the chamber is lowered to a pressure below ambient pressure by movement of the piston. Thus, the tobacco comprised in the chamber can be immediately expanded without any previous pressure build-up in the chamber.
Alternatively, the method comprises increasing the pressure in the chamber to a pressure above ambient pressure by movement of the piston, and subsequently rapidly lowering the pressure to ambient pressure. The subsequent rapid lowering of the pressure to ambient pressure expands the tobacco. Preferably, the pressure in the chamber is maintained at an elevated pressure for a certain time. Preferably the elevated pressure is between about 0.5 bar above atmospheric pressure and about 8 bar above atmospheric pressure. Preferably, the elevated pressure is maintained between about 30 minutes and about 24 hours, more preferably, the elevated pressure is maintained between about 8 hours and about 24 hours.
Preferably, the temperature of the chamber is increased before the reduction in pressure. Preferably, the temperature is increased between about 5 degrees Celsius and about 250 degrees Celsius, more preferably between about 25 degrees Celsius and about 200 degrees Celsius.
Maintaining the tobacco at an elevated temperature or at an elevated pressure or at both an elevated temperature and an elevated pressure for a given amount of time facilitates the impregnation of the tobacco by the treatment medium. A good impregnation of the tobacco by the treatment medium raises the efficiency of the subsequent expansion.
Preferably, the movement of the piston is applied to rapidly lower the pressure to ambient pressure in the chamber.
Alternatively, the pressure is lowered from a pressure above ambient pressure to a pressure below ambient pressure by means of piston movement in the cylinder.
Preferably, the lowering of the pressure to ambient pressure is enabled by opening an air bleed valve, wherein the air bleed valve is preferably provided within in the cylinder. Thus, the tobacco will be expanded by the drop of pressure caused by the opening of the air bleed valve. Alternatively, the air bleed valve is provided in the chamber.
Preferably the pressure drop is in the range between about 0.01 bar and about 10 bar, more preferably between about 0.1 bar and about 5 bar and most preferably between about 0.5 bar and about 3 bar.
Preferably the time to create the pressure drop, for example to decrease from ambient pressure to a pressure below ambient pressure or to decrease from over pressure to atmospheric pressure is in the range between about 0.01 seconds and 5 minutes, more preferably between about 0.05 seconds and 0.2 minute and most preferably between about 0.1 second and about 0.5 seconds. Preferably, the first opening is on top of the chamber and the second opening is on the bottom of the chamber, such that gravitational force can be used for the transportation of the tobacco through the expansion apparatus.
Preferably, a treatment medium is injected to the chamber via an injection valve. The treatment medium may be any medium facilitating the tobacco expansion. Preferably, the treatment medium comprises at least one of saturated steam, superheated steam, air, carbon dioxide, Nitrogen, Argon or water. Preferably, where the treatment medium is saturated steam, the saturated steam is under a pressure of about 10 bars at about 184 degrees Celsius. Preferably, where the treatment medium is superheated steam, the superheated steam is under a pressure of between about atmospheric pressure and about 4 bars and at a temperature of between about 120 degrees Celsius and 250 degrees Celsius, more preferably between about 160 degrees Celsius and 250 degrees Celsius. In particular, the medium is suitable to reduce the oxygen concentration in the chamber before creating a given temperature or pressure therein. The reduction of the oxygen concentration within the chamber may reduce or prevent an adverse effect of the expansion treatment on the subjective of the tobacco.
Preferably, the method according to the invention further comprises the steps of circulating the treatment medium to flush the chamber by first injecting the treatment medium through the injection valve into the chamber, then discharging the treatment medium through a purge valve installed in the chamber or cylinder, and then feeding the discharged treatment medium to the injection valve. Thus, the tobacco can be more efficiently treated by the treatment medium as further circulation enables that substantially all of the tobacco can be reliably subjected to the treatment medium. Furthermore, this allows to more efficiently removing remaining oxygen from the chamber.
Preferably, the method according to the invention further comprises the steps of providing at least two substantially hermetically sealable chambers on a revolving member, wherein each of the at least two substantially hermetically sealable chambers have at least one loading position, at least one pressurizing position and at least one discharging position. According to the invention the at least one loading position, the at least one pressurizing position and the least one discharging position may coincide, such that loading of a chamber, pressurization (or depressurization) of a chamber and discharging of the tobacco from a chamber are effected at the same physical location. Alternatively, at least one of the at least one loading position, the at least one pressurizing position or the least one discharging position does not coincide with the other positions. For example, the method according to the invention may comprise the step of loading of a first blend of tobacco into a first chamber at a first loading position and the step of loading a second blend of tobacco into the same first chamber at a second loading position, the subsequent step of pressurizing the first chamber at a first and at a second pressurizing position, depressurizing the chamber in a third pressurization position and the step of discharging the expanded tobacco from the first chamber at a single discharging position wherein the single discharging position coincides with the first loading position.
Preferably, the method according to the invention further comprises the steps of rotating the revolving member and maintaining the tobacco in one of the chambers at a pressure different from ambient pressure during the rotation of the revolving member. Subsequently, the tobacco is discharged from the chamber, when the chamber is in the discharging position. The revolving member provides the benefit, that one or several loading positions can be defined where means are provided that allow to easily fill the chamber with tobacco. The tobacco which has been filled into the chamber in the loading position can be maintained at the pressure different from ambient pressure for a certain time while the revolving member is rotated such that the chamber comprising the tobacco moves from the loading position to the discharging position. By subsequently filling chambers at the loading position and discharging the tobacco at the discharging position, an almost continuous tobacco expansion process can be implemented improving the throughput and the efficiency of the tobacco expansion method.
In addition, the method according to the invention may comprise the step of parking a pressurized chamber in a parking position, where the chamber is maintained at a given pressure and temperature for an extended amount of time. Preferably, the parking position of the chamber is outside of the rotating member, for example in a storing means. In that case, the method according to the invention further comprises the steps of unloading the pressurized chamber into the parking position in a storing means from the revolving member and loading the pressurized chamber from the parking position in the storing means onto the revolving member. Preferably, the storing means accommodates a plurality of storing members, for example between 2 and about 100 chambers. This way, a continuous expansion of the tobacco can be efficiently performed even where the tobacco is impregnated in the chambers for an extended amount of time.
In one embodiment, the substantially hermetically sealable chamber is pressurized with a separate cylinder provided for each of the substantially hermetically sealable chambers. This is beneficial insofar that the pressure in the chamber can be continuously controlled even during the rotation of the revolving member. Furthermore, the cylinder provided for each of the substantially hermetically sealable chambers can be connected to the corresponding substantially hermetically sealable chamber in a reliable and easy manner.
Alternatively, the substantially hermetically sealable chamber filled with tobacco is pressurized in a pressurizing position by a stationary cylinder in communication with the substantially hermetically sealable chamber in the pressurizing position. Thus, all the substantially hermetically sealable chambers of the revolving member can be pressurized subsequently by only one stationary cylinder. Alternatively, several stationary cylinders pressurize the substantially hermetically sealable chamber in several pressurizing positions.
Preferably, the cylinder and the chamber are separated by a screen which is permeable for fluids but not for the tobacco. Thus, the tobacco can be reliably kept out of the cylinder or a fluid communication duct or pipes connecting the cylinder and the chamber. In particular, the screen is provided within the chamber close to the opening of a fluid communication connecting the cylinder with the chamber.
The present invention also relates to a tobacco expansion apparatus comprising at least one substantially hermetically sealable chamber and a pressure cylinder in communication with the at least one chamber, wherein the pressure cylinder comprises a piston and is adapted to alter the pressure in the at least one chamber to a pressure different from ambient pressure. The tobacco in the at least one substantially hermetically sealable chamber can be subjected to different pressures for the expansion of the tobacco in a quick and reliable manner. Preferably, the tobacco expansion apparatus comprises locks for opening and closing the substantially hermetically sealable chambers, wherein the locks are slidable or pivotable to enable the opening and closing of the chambers. Thus, the chambers can be easily opened to enable that tobacco is filled into the chamber, and that the expanded tobacco is discharged from the chamber.
In particular, the tobacco expansion apparatus comprises several substantially hermetically sealable chambers, wherein each of the chambers is adapted to be subsequently located in a loading position, where tobacco can be filled in the respective chamber through a loading lock. The tobacco expansion apparatus may comprise 2, 3, 4, 5, 6, 8, 10, 12, 24, 50 or more chambers or any other number of chambers. The chambers may have different sizes but uniform size is preferred.
Preferably, the volume of a chamber is between about 0.001 cubic meters and about 10 cubic meters, more preferably between about 0.01 cubic meters and 2 cubic meters and most preferably between about 0.1 cubic meters and about 1 cubic meter.
Further, each of the chambers is adapted to be located in a discharging position, where tobacco can be discharged from the respective chamber through a discharging lock. Thus, by being able to locate each of the chambers in a loading position and also in a discharging position, an efficient and almost continuous process of tobacco expansion can be implemented. Further, stationary means for filling the tobacco can be provided close to the chamber in the loading position and stationary discharging means can be located close to the chamber in the discharging position.
Preferably, the several substantially hermetically sealable chambers are provided on a revolving member, which is adapted to be rotated. Thus, the rotation enables that the chambers can be subsequently located in the loading position and discharging position.
However, alternatively, the substantially hermetically sealable chamber may also be provided on a member that is linearly moveable.
In addition, the tobacco expansion apparatus comprises a storing means for pressurized chambers in a parking position as explained above.
Preferably, the treatment medium is injected through an injection valve, which allows dosing the amount of injected medium. Preferably, the injection valve provides the function of recirculation.
In order to provide the function of recirculation the pressure piston is provided with a purge opening with a purge valve such that the treatment medium is injected through the injection opening in the chamber. Likewise, air or treatment medium that has already been in the pressure cylinder can be discharged from the pressure cylinder.
In another embodiment the recirculation opening may be provided in the chamber itself.
Furthermore, the tobacco expansion apparatus can be provided with an air bleed valve which can be located at the cylinder or in the chamber, but is preferably located at the fluid communication duct between the chamber and the cylinder. The air bleed valve can be opened to create a sudden pressure change in the chamber and pressure cylinder, in particular to suddenly release air or treatment medium of a high pressure from the chamber and the pressure cylinder. Alternatively, the reduction of pressure is achieved by a fast retraction of the piston of the pressure cylinder. The air bleed valve and the purge valve may be implemented as the same valve.
In use, the tobacco expansion apparatus is preferably operated according to the following two operation modes, namely a "pressurized-mode" and a "vacuum-mode".
In the "pressurized-mode" first the loading lock of the tobacco chamber is opened and tobacco is inserted into the chamber. Then, the loading lock is closed and steam is injected through the injection valve into the chamber while the purge valve at the pressure cylinder is opened. Thus, the steam first fills the chamber while replacing the air in the chamber which streams through the screen, via the communication duct into the pressure cylinder and through the purge valve. When the air formerly comprised in the chamber and pressure cylinder has been completely replaced by steam, the steam injection can be stopped. Optionally, a recirculation step can be carried out by circulating the steam which is discharged through the purge valve to the injection valve to ensure that all tobacco in the chamber has been subjected sufficiently to the steam.
The piston of the pressure cylinder which is initially in a retracted position is then moved to create a high pressure in the chamber. The retracted position refers to a position where the volume of the cylinder connected to the chamber is maximal or at least relatively large. Throughout this process the injection valve, the purge valve and the air bleed valve are closed. However, alternatively, or additionally, pressure in the chamber can be created as well by the injection of high-pressure steam through the injection valve. The tobacco is maintained for a certain time at high pressure such that all of the tobacco is subjected to the steam at high pressure.
The pressure is then released suddenly either by the movement of the piston or the opening of the air bleed valve. The sudden pressure relief causes a quick phase change of water inside the tobacco from liquid to vapor, and thus expands the tobacco. Alternatively the sudden release of the pressure is obtained by retracting the piston and opening the air bleed valve at the same time.
In the last step, the discharging lock at the bottom of the tobacco chamber is opened and the expanded tobacco is discharged.
In the "vacuum-mode" tobacco is provided through the loading lock into the chamber, while the piston of the pressure cylinder is in the forward position to initially enable the smallest volume in the pressure cylinder.
Then, the loading lock is closed and steam is injected through the injection valve and discharged through the purge valve as already described above. After an optional recirculation of the steam, the steam injection valve and the purge valve are both closed and the piston of the pressure cylinder is retracted such that the volume in the pressure cylinder is suddenly increased to create a pressure in the pressure cylinder and tobacco chamber which is significantly lower than the ambient pressure. This pressure allows the expansion of the tobacco.
Subsequently, for repressurization the air bleed valve is opened to increase the pressure in the chamber and pressure cylinder again to ambient, respectively atmospheric pressure. Additionally, or alternatively, a movement of the piston of the pressure cylinder can be conducted for the repressurization process. Finally, the discharging lock of the chamber is opened and the expanded tobacco is discharged.
The invention will be further described, by way of example only, with reference to the accompanying drawings in which:
FIG. 1 is an elevated front perspective view of a tobacco expansion apparatus according to an embodiment of the invention, and
FIG. 2 is a horizontal cross sectional view of the tobacco expansion apparatus according to the embodiment of the invention. The tobacco expansion apparatus 1 as shown in FIG. 1 comprises a revolving member 2, which can be rotated around a rotational axis 3, which is substantially vertically arranged in a generally central location of the revolving member 2.
The dashed lines of FIG. 1 indicate portions of the tobacco expansion apparatus which would usually be hidden, as they are within the tobacco expansion apparatus or on the rear side of the tobacco expansion apparatus.
In this embodiment, the revolving member 2 has a substantially cylindrical outer form and circular flat upper and lower surfaces. The rotational member 2 can be driven by any suitable driving means such as a servo motor or a stepper motor.
The revolving member 2 is provided with tobacco chambers 3, 4 which are located in the radial outer region of the revolving member 2 as seen from the rotation axis 3. The tobacco chambers 3, 4 extend from a top surface to a lower surface of the revolving member 2.
In particular, the tobacco chambers 3, 4 comprise a loading opening at the top side of the revolving member 2. The loading opening can be closed by means of a loading lock 5, 6 which is pivotally mounted at one side of the loading opening. In FIG. 1 the loading lock 5 of the tobacco chamber 3 is opened and the loading lock 6 of the tobacco chamber 4 is closed.
Furthermore, the tobacco chambers 3, 4 comprise discharge openings at the lower side of the revolving member 2, which can be closed by pivotable discharging locks 7, 8 which are both depicted as closed in FIG. 1.
The tobacco expansion chambers 3, 4 are substantially hermetically sealable when the loading locks 5, 6 and discharging locks 7, 8 are closed. Only a fluid communication duct 9, 10 connects the chambers 3, 4 to the lower part 11, 13 of the pressure cylinder 12. The pressure cylinder 12 comprises a piston 14 which can be moved through an upper part 15 and the lower part 11 , 13 of the pressure cylinder to alter the pressure in the pressure cylinder 12.
FIG. 1 shows a split pressure cylinder, comprising a rotating cylinder section and a stationary cylinder section. The pressure cylinder 12 comprises the lower part 11 , the upper part 15 and the piston 14, while the tobacco chamber 8 is only connected to the lower part 13 of the split pressure cylinder without an upper part or piston. In use, the stationary upper part 15 and piston 14 of the split pressure cylinder 12 are brought into alignment with the lower part 11 , 13 in the revolving member 2.
Additionally, a valve may be provided in the communication duct 9, 10 such that the pressure in the chamber 3, 4 can be kept at a level different from ambient pressure, even if the upper part 15 and the piston 14 are not connected to the lower part 11 , 13 of the pressure cylinder 12. This provides the benefit that the piston 14 and the respective actuation means have only to be provided at the depicted position, while the respective lower part 11 , 13 of the pressure cylinder can be brought into alignment with the piston 14 by means of rotation of the revolving member 2 around the rotation axis 3.
However, alternatively, a fully equipped pressure piston can be provided for each of the chambers 3, 4.
Each of the chambers 3, 4 comprises an injection opening through which under control of an injection valve 16, 17 a medium such as steam can be injected into chamber 3, 4. A purge valve 18, 19 is provided on the lower part 11 , 13 of the pressure cylinder 12 to enable the air which is replaced by steam injected through the injection valve 16, 17 to be discharged. An air bleed valve may be provided at a similar position as the purge valve 18, 19. Alternatively, the air bleed valve and the purge valve 18, 19 are the same valve.
In an embodiment, it is possible that the purge valve 18, 19 is in fluid communication with the injection valve 16, 17 via a recirculation pipe to allow the recirculation of medium discharged through the purge valve 18, 19 to the injection valve 16, 17 and back into the chamber 3, 4.
In FIG. 2 a horizontal cross section through the tobacco expansion apparatus is shown. Further tobacco chambers 24, 25, 26, 27 are provided in the revolving member 2 which are not depicted in FIG. 1. The chambers 24, 25, 26, 27 are respectively in fluid communication with the lower parts 20, 21 , 22, 23 of pressure cylinders 12 via the communication ducts 28, 29, 30, 31. The number of chambers for the expansion of tobacco in the revolving member 2 can be any number, while in FIG. 1 for the sake of clarity only two chambers 3, 4 are depicted. For a real production environment a higher number of chambers like, 4, 6, 8, 12, 16, or 24 is desirable, as this allows the increase of the throughput of tobacco. In use, the tobacco is provided in a tobacco chamber which is in the position of the tobacco chamber 3. At the same time, already expanded tobacco is discharged from the tobacco chamber in the position of the chamber 24. When chamber 3 is filled with the designated amount of tobacco, the respective loading lock 5 is closed and the pressure in the chamber 3 is altered to a pressure different from ambient pressure. Then, the revolving member 2 is rotated by sixty degrees in a clockwise direction, the loading lock of the chamber 24 is opened and tobacco is provided to the chamber 24. In parallel, tobacco is discharged from chamber 25. Thus, as depicted in FIG. 2, chamber 3 is in a loading position and chamber 24 is in a discharging position. Further, chamber 3 is in the pressurizing position.
The pressure in chamber 23 is released by means of retraction of the piston or by opening of the air bleed valve. Then, the discharging lock is opened. Thus, after revolving the rotation member by sixty degrees, one tobacco chamber can be filled while another is emptied at the same time. This allows the operation of a method for tobacco expansion in the tobacco expansion apparatus that has a high throughput and efficiency.