EXTRACTION APPARATUS WITH SCREW CONVEYORS FOR TOBACCO MATERIAL

Abstract

The apparatus for the extraction of ingredients from plant material, in particular alkaloids or tobacco flavors from tobacco material comprises a first screw conveyor (1, 22) with at least one rotatably driven first screw (8, 25, 26), which is adapted to convey the plant material from a first screw conveyor inlet (3, 37) to a first screw conveyor outlet (4). The apparatus further comprises a second screw conveyor (9, 23) with at least one rotatably driven second screw (9, 27, 28), which is adapted to convey the plant material from a second screw conveyor inlet (6) to a second screw conveyor outlet (7). A fluid connection (5, 38) is provided in between the first screw conveyor outlet (4) and the second screw conveyor inlet (6). The fluid connection is adapted to enable flow of plant material from the first screw conveyor outlet to the second screw conveyor inlet. The first screw conveyor has a first fluid outlet at its downstream side. The second screw conveyor has a second fluid outlet at its downstream side.

Claims

1. Apparatus for the extraction of ingredients from plant material, in particular alkaloids or tobacco flavors from tobacco material, comprising a first screw conveyor with at least one rotatably driven first screw, which is adapted to convey the plant material from a first screw conveyor inlet to a first screw conveyor outlet, and a second screw conveyor with at least one rotatably driven second screw, which is adapted to convey the plant material from a second screw conveyor inlet to a second screw conveyor outlet, wherein a fluid connection is provided in between the first screw conveyor outlet and the second screw conveyor inlet, the fluid connection being adapted to enable flow of plant material from the first screw conveyor outlet to the second screw conveyor inlet, wherein the first screw conveyor has a first fluid outlet at its downstream side, and wherein the second screw conveyor has a second fluid outlet at its downstream side.

2. Apparatus according to claim 1, wherein at least one of the screw conveyors has two rotatably driven screws arranged therein.

3. Apparatus according to claim 2, wherein the crests of the threads on the proximal sides of the screws are adjacent to each other.

4. Apparatus according to claim 1, comprising a third screw conveyor with at least one rotatably driven screw, which is adapted to convey the plant material from a third screw conveyor inlet to a third screw conveyor outlet.

5. Apparatus according to claim 1, wherein in at least one of the screw conveyors, the pitch of the threads of the at least one rotatably driven screw is varied.

6. Apparatus according to claim 1, wherein in at least one of the screw conveyors the diameter of the shaft of the at least one rotatably driven screw is varied along the axial direction of the screw.

7. Apparatus according to claim 1, wherein at least one of the screw conveyors comprises a sieve being arranged at least partially in the axial and circumferential direction adjacent to the screw, to allow the separation of fluid from the plant material.

8. Apparatus according to claim 1, wherein at least one of the screw conveyors comprises a fluid inlet at its upstream side.

9. Apparatus according to claim 1, wherein at least one of the screw conveyors is adapted to alter the pressure in the tobacco material while conveying the tobacco material.

10. Method for the extraction of at least one alkaloid or at least one tobacco flavor from tobacco material, in particular from preprocessed tobacco material, with the following steps: mixing tobacco material and an extracting liquid, and continuously conveying the tobacco material and extracting liquid, while separating the extracting liquid from the tobacco material, wherein the tobacco material is continuously conveyed through subsequent stages, wherein in each of these stages, extracting liquid is at least partially separated from the tobacco material at a downstream position.

11. Method according to claim 10, wherein in each of the stages, extracting liquid is injected at an upstream position.

12. Method according to claim 10, wherein the temperature of the tobacco material at the end of the second stage is higher than the temperature of the tobacco material at the end of the first stage.

13. Method according to claim 10, wherein the pressure in the tobacco material at the end of the second stage is higher than the pressure in the tobacco material at the end of the first stage.

14. Method according to claim 10, wherein the conveying is effected by at least two subsequent screw conveyors, wherein a friction factor of the screw conveyor increases at least partially in the downstream direction.

15. Use of a screw conveyor for extracting at least one alkaloid or at least one tobacco flavor from tobacco material, in particular from preprocessed tobacco material, wherein the tobacco material is continuously conveyed through subsequent stages, wherein in each of these stages, extracting liquid is at least partially separated from the tobacco material at a downstream position.

Description

[0084] Embodiments of the invention will now be further described with reference to the figures in which:

[0085] FIG. 1 shows a schematic cross-sectional view of an embodiment of the inventive apparatus.

[0086] FIG. 2 shows a schematic cross-sectional view of a further embodiment of the inventive apparatus.

[0087] In FIGS. 1 and 2 different embodiments of the inventive apparatus are depicted, wherein their structure is explained together with embodiments of the inventive method and use.

[0088] In the embodiment according to FIG. 1, the apparatus comprises a first screw conveyor 1, and a subsequent second screw conveyor 2, through which tobacco material comprising extracting liquid is continuously conveyed. The tobacco material is initially provided to the first screw conveyor 1 through a first screw conveyor inlet 3, and conveyed along the conveying direction 100 to a first screw conveyor outlet 4. The first screw conveyor outlet 4 is connected over a fluid connection 5, in the form of a pipe, to a second screw conveyor inlet 6.

[0089] In the second screw conveyor 2, the tobacco material is conveyed along the conveying direction 100 to the second screw conveyor outlet 7. The first screw conveyor 1 comprises a first screw 8 and the second screw conveyor 2 comprises a second screw 9. The first screw 8 and the second screw 9 are driven by a drive 10, in particular an electric motor. The first screw 8 and the second screw 9 may be connected via a shaft 11 or another mechanical connection, such as a gear. This enables, that the screws 8 and 9 may both be driven by only one drive. Alternatively, the first screw 8 and the second screw 9 may have mechanically separate shafts, only synchronized by electronic control of their respective drives. The first screw conveyor 1 comprises furthermore a fluid inlet 12. Extracting liquid may be provided through the fluid inlet 12 and mixed with the tobacco components, in the form of raw tobacco material, provided through the inlet 3. The mixture of the raw tobacco material and the extracting liquid is then conveyed through the first screw conveyor 1, which provides a first processing stage of the inventive extraction method. In particular, the raw tobacco material provided through the first screw conveyor inlet 3 may be tobacco leaves or preprocessed tobacco from other manufacturing processes. The raw tobacco material may in particular be dried or fermented or dried and fermented. The raw tobacco material may be fed without any extracting liquid through the first screw conveyor inlet 3. The raw tobacco material is mixed with extracting liquid, and then, in the first screw conveyor 1, subjected to a progressive increase of pressure and temperature, including rough-cutting or rough-gridding by means of the screw 8, for the purpose of homogenizing the raw tobacco material and extracting liquid to form a homogenized tobacco material. Thus, the raw tobacco material does not need to be cut before feeding it to the first screw conveyor 1, which enables an accelerated processing, for all types of raw tobacco material from the entire leaves to tobacco dust.

[0090] The first screw conveyor inlet 3 is configured to have a pulling effect, such that the tobacco material in the inlet 3 is automatically pulled into the first screw conveyor 1. At the downstream end of the first stage in the form of the first screw conveyor 1, the volume of the tobacco material may have been increased by means of absorption of the extracting liquid, and the tobacco material may be substantially homogenized and chemically consistent. At the downstream end of the first screw conveyor 1, a fluid outlet 13 may be provided. In particular, a sieve 14 is arranged in the outlet 13, preferably directly adjacent to the first screw 8. This enables that extracting liquid comprising extracted tobacco flavors and alkaloids, such as nicotine, may be separated from the tobacco material.

[0091] Thus, at the end of the first stage, an initial extraction may have been completed. In particular, the first screw 8 comprises an inner shaft 15, whose diameter increases in the conveying direction 100. Furthermore, the first screw 8 comprises a helical thread 16, whose outer diameter remains the same along the conveying direction 100. This means that the conveying volume continuously decreases in the conveying direction, leading to an increase of pressure in the tobacco material along the first process stage in the first screw conveyor 1.

[0092] Since the extracting liquid 12 injected through the first fluid inlet 12 may be heated, the temperature of the tobacco material is also increased throughout the first stage. Additionally, heating elements, which are not depicted in the figures, may be provided for the heating of the tobacco material.

[0093] After leaving the first screw conveyor 1 and passing the fluid connection 5, the tobacco material enters the second screw conveyor 2 via the second screw conveyor inlet 6. The second screw conveyor 2 comprises a fluid inlet 17 at its upstream end, through which further extracting liquid may be injected. The tobacco material is conveyed and maintained at a temperature and pressure in the second screw conveyor 2, which are higher than the temperature and pressure in the first screw conveyor 1. The second screw conveyor 2 comprises a fluid outlet 18, which extends at least halfway along the conveying direction 100 in the second screw conveyor 2. The fluid outlet 18 may comprise a sieve 19, which is arranged directly adjacent to the second screw 9. While the tobacco material is conveyed by means of the second screw 9, extracting liquid is extracted from the tobacco material through the sieve 19 and is collected in the fluid outlet 18. The remaining tobacco material is subsequently ejected through the outlet 7 at the downstream end of the second screw conveyor 2.

[0094] The diameter of the inner shaft 20 of the second screw 9 remains constant along the conveying direction. The helical threads 21 also have a constant outer diameter. A constant pitch of the helical threads 21 is provided in the upstream half of the second screw 9. However, at the downstream end of the second screw 9, the pitch of the helical threads 21 may become larger, to reduce the pressure before the tobacco material is ejected through the outlet 7. Thus, the second stage enables to extract a large quantity of the alkaloids and tobacco flavors from the tobacco material.

[0095] Overall, it is beneficial to start gentle in the beginning of the first stage with cold pressing and then increase temperature and pressure with each stage. This means that the extracted ingredients may be different from each other along the subsequent fluid outlets.

[0096] In FIG. 2, a second embodiment of an inventive apparatus is shown. In this embodiment, three screw conveyors are arranged subsequently in the conveying direction 100, namely a first screw conveyor 22, a second screw conveyor 23, and a third screw conveyor 24. Each screw conveyors comprises two parallely arranged screws, namely the first screw conveyor screws 25, 26, the second screw conveyor screws 27, 28, and the third screw conveyor screws 29, 30. Each screw conveyor 22, 23, 24 comprises a fluid inlet and a fluid outlet, in particular for injecting extracting liquid, and collecting extracting liquid with tobacco flavors and alkaloids, respectively. The first screw conveyor 22 comprises a fluid inlet 31 and a fluid outlet 32, the second screw conveyor comprises a fluid inlet 33 and a fluid outlet 34, the third screw conveyor comprises a fluid inlet 35 and a fluid outlet 36. The first screw conveyor 1 comprises a first screw conveyor inlet 37 for raw tobacco material. In between the first screw conveyor 22 and the second screw conveyor 23, a fluid connection 38 for the transfer of tobacco material from the first screw conveyor 22 to the second screw conveyor 23 is provided. In between the second screw conveyor 23 and the third screw conveyor 24, a fluid connection 39 is provided for the transfer of tobacco material in between the second screw conveyor 23 at the third screw conveyor 24. A drive 40 is provided for driving the screws of the respective screws conveyors 22, 23, 24. In particular, all screws 25, 26, 27, 28, 29, 30 may be mechanically coupled by gears or drive shafts, such that all screws can be driven with only one drive 40.

[0097] In the first stage in the form of the first screw conveyor 22, the tobacco material is subjected to an extracting liquid, which is injected through the first fluid inlet 31. The temperature and pressure of the tobacco material is progressively increased in the first stage. Furthermore, the tobacco material is homogenized in the first stage. Extracting liquid with extracted tobacco flavors and alkaloids may already be collected at the fluid outlet 32.

[0098] In the second stage in the form of the second screw conveyor 23, further extracting liquid, in particular in the form of water or water vapor is injected through the fluid inlet 33. Thus, the homogenized tobacco material and the extracting liquid is conveyed through the second stage, and the extracting liquid is separated from the tobacco material at the fluid outlet 34.

[0099] In the second stage, the pressure and temperature is preferably progressively increased, for the purpose of keeping the extracting liquid, in particular water and potentially extracting agents in a homogeneous mixture with the solid parts of the tobacco material, to enable extraction.

[0100] Thus, the extracting liquid will have an increased content of tobacco flavors and alkaloids at the end of the second stage, when it is collected at the fluid outlet 34. In the third stage, the third screw conveyor 24 may exert still higher pressure on the tobacco material, and additional extracting liquid may be injected. Thus, the remaining tobacco flavors and alkaloids can be extracted. In particular, in the third stage the pressure and temperature is maintained at a high level or even increased at the upstream end. The pressure may be reduced at the downstream end of the third screw conveyor 24, by means of changing the pitch and design of the helical threads of the screws 29, 30. At the downstream end of the third screw conveyor 24, the shear forces in the tobacco material may be increased, which enables further extraction from the tobacco material. The tobacco material is then discharged at the outlet 41.

[0101] The extracting liquid comprising tobacco flavors and alkaloids may be further processed and used for aerosol generating articles, for example electronic cigarettes.

[0102] Thus, according to the invention it is possible to enable an extraction process, in which several process parameters, such as temperature, pressure, and friction, may be continuously altered along the conveying direction. This enables a continuous process with characteristics, which can be optimized for the respective processed raw tobacco material. For example, the shear forces may be increased in the first stage, when processing larger leaves or leaf parts of tobacco material, to disintegrate these larger leaves or leaf parts into smaller parts. The pressure may be increased when processing preprocessed tobacco material. Furthermore, a washing step may be included in the first stage to wash preprocessed or raw tobacco material. Furthermore, different processing stages enable to use subsequently different extracting agents and liquids, which are adapted to the respective tobacco material present in the stages.