Patent ID: 12213511

FIG.1shows a schematic partial view of a rotary dryer1for drying herbaceous material, in particular tobacco material. The rotary dryer1comprises a dryer receptacle3having an inner space5for receiving the herbaceous material. The dryer receptacle3can be rotated about a rotation axis10of the dryer receptacle3. The dryer receptacle3comprises a main body7extending from a first side9of the main body7(inlet side according to the present embodiment) to a second side11of the main body7(outlet side according to the present embodiment) along the rotation axis10. In the illustrated embodiment, the main body7of the dryer receptacle3is substantially cylindrically shaped. However, also other shapes of the main body7are conceivable, such as a prismatic shape, for example. The dryer receptacle3further comprises a first door13provided at the first side9of the main body7. Further, the dryer receptacle3comprises a second door15provided at the second side11of the main body7. The doors13,15can be opened to access the inner space5of the dryer receptacle3for maintenance or loading. When closed, the doors13,15provide a substantially airtight seal together with the main body7of the dryer receptacle3. The substantially airtight seal allows control over gases flowing into and out of the inner space5of the dryer receptacle3. For example, the oxygen content in the inner space5of the dryer receptacle3may be controlled. According to an embodiment, there is an overpressure in the inner space5of the dryer receptacle3to avoid ambient atmosphere from entering the inner space5of the dryer receptacle3in an uncontrolled manner. When the dryer receptacle3is rotated, the main body7and the doors13,15rotate together.

In some embodiments, the herbaceous material may be manually or automatically loaded into or removed from the dryer receptacle3through the opened doors13,15. In the illustrated embodiment, however, the herbaceous material is loaded into and withdrawn from the inner space5of the dryer receptacle3when the doors13,15are closed. An inlet system17is provided at the first door13to feed herbaceous material into the dryer receptacle3. The inlet system17comprises an inlet duct19extending through a central opening in the door13. The inlet duct19is stationary and does not rotate together with the dryer receptacle3. The inlet duct19is connected to the first door13via a substantially airtight rotation decoupling seal21. Herbaceous material to be supplied to the inner space5of the dryer receptacle3is supplied to an inlet23of the inlet system17. As illustrated inFIG.2, an inlet conveyor25is provided inside the inlet duct19. In the illustrated embodiment, the inlet conveyor25comprises a conveyor screw that is rotated by a drive assembly27about a rotation axis that is parallel and coaxial to the rotation axis10of the dryer receptacle3. Alternatively, the inlet conveyor25may comprise a rotated spiral for feeding the herbaceous material into the inner space5of the dryer receptacle3. As another alternative, the inlet conveyor25may comprise a scraper configured to move back and forth for feeding the herbaceous material into the inner space5of the dryer receptacle3. If the inlet conveyor25comprises, for example, a conveyor screw, or a rotated spiral, or a scraper, the inlet conveyor25comprises an active conveying system. However, the inlet conveyor25could alternatively be configured as passive conveying system. In particular, the inlet conveyor25could comprise a chute for feeding the herbaceous material into the inner space5of the dryer receptacle3. The inlet conveyor25could be configured to feed the herbaceous material into the inner space5of the dryer receptacle3without using any actively driven components. The inlet conveyor25conveys herbaceous material supplied to the inlet23of the inlet system17into the inner space5of the dryer receptacle3.

Analogously, an outlet system29is provided at the second door15to withdraw herbaceous material from the inner space5of the dryer receptacle3. The outlet system29comprises an outlet duct31extending through a central opening in the door15. The outlet duct31is stationary and does not rotate together with the dryer receptacle3. The outlet duct31is connected to the second door15via a substantially airtight rotation decoupling seal33. As illustrated inFIG.2, an outlet conveyor37is provided inside the outlet duct31. The outlet conveyor37comprises a conveyor screw that is rotated by a drive assembly39about a rotation axis that is parallel and coaxial with the rotation axis10of the dryer receptacle3. Alternatively, the outlet conveyor37may comprise a rotated spiral for removing the herbaceous material from the inner space5of the dryer receptacle3. As another alternative, the outlet conveyor37may comprise a scraper configured to move back and forth for removing the herbaceous material from the inner space5of the dryer receptacle3. If the outlet conveyor37comprises, for example, a conveyor screw, or a rotated spiral, or a scraper, the outlet conveyor37comprises an active conveying system. However, the outlet conveyor37could also be configured as passive conveying system. In particular, the outlet conveyor37could comprise a chute for removing the herbaceous material from the inner space5of the dryer receptacle3. The outlet conveyor37could be configured to remove the herbaceous material from the inner space5of the dryer receptacle3without using any actively driven components. The outlet conveyor37conveys herbaceous material from the inner space5of the dryer receptacle to an outlet35of the outlet system29.

As shown inFIG.2, the dryer receptacle3may be mounted on a tilting device41for adjusting a tilting angle of the dryer receptacle3with respect to a horizontal plane. InFIG.2, the dryer receptacle3is in a horizontal position, meaning that the tilting angle is zero. The tilting device41comprises an arm43carrying the dryer receptacle3. The arm43can be tilted via a hinge45and a hydraulic cylinder47, thereby tilting the dryer receptacle3by raising the inlet side9of the dryer receptacle3with respect to the outlet side11. The tilting device41may be configured to establish a tilting angle between 0 degrees and 90 degrees, or between 0 degrees and 60 degrees, or between 0 degrees and 45 degrees, or between 0 degrees and 30 degrees, or between 0 degrees and 15 degrees, or between 0 degrees and 10 degrees for example.

The dryer1can be operated in two different operational modes. In a batch mode, a load of the herbaceous material is first loaded into the dryer receptacle3, then dried in the dryer receptacle3, and then removed from the dryer receptacle3. During drying, the inlet conveyor25and the outlet conveyor37may be rotated to push material at the inlet and outlet sides9,11back into the inner space5.

In detail, in the batch mode, the herbaceous material to be dried may be introduced into the inner space5of the dryer receptacle3via the inlet system17, while the inlet side9of the dryer receptacle3is raised with respect to the outlet side11. Preferably, the dryer receptacle3is rotated during introduction of the herbaceous material. When all the material has been loaded into the inner space5of the dryer receptacle3, the tilting device41lowers the inlet side9of the dryer receptacle3until the dryer receptacle3is horizontally aligned. The material is then processed for a desired amount of time, while the dryer receptacle3is rotated. During this time, the inlet conveyor25and the outlet conveyor37may be rotated to push material at the inlet side9and at the outlet side11back into the inner space5. After expiry of the desired time, the inlet side9of the dryer receptacle3is again raised with respect to the outlet side11, and the rotation direction of the outlet conveyor37is reversed so that the outlet conveyor37conveys the herbaceous material to the outlet35. During this process, the dryer receptacle3may still rotate.

According to a continuous mode, herbaceous material is introduced into the inner space5of the dryer receptacle3and withdrawn from the inner space5of the dryer receptacle3continuously. The inlet conveyor25may continuously rotate to supply herbaceous material from the inlet23to the inner space5of the dryer receptacle3, while the outlet conveyor37continuously rotates to remove herbaceous material from the inner space5of the dryer receptacle3to the outlet35. Residence time of the herbaceous material in the inner space5of the dryer receptacle3can be regulated by appropriately setting the inclination of the dryer receptacle3via the tilting device41. Additionally or alternatively, the speed of rotation of the dryer receptacle3may be regulated.

As stated above, the dryer receptacle3is provided to be substantially airtight. Preferably, drying of the herbaceous material in the dryer receptacle3is carried out under specific atmospheric conditions. This allows better control over the process. Further, yield of high-quality dried product may be improved by controlling the atmosphere in the dryer receptacle3. The drying process can be carried out under inert gas atmosphere in the dryer receptacle3. Inert gases in the inner space5of the dryer receptacle3may reduce the risk of fire. In particular, when processing tobacco material, it can be beneficial to carry out the drying process under nitrogen atmosphere. The nitrogen can, in particular, function as an inert gas. Also, other inert gases or mixtures of gases comprising inert gases could be used. In particular, the atmosphere in the dryer receptacle3could comprise noble gases. Nitrogen or another gas or a mixture of gases may, for example be provided to the dryer receptacle3via a gas inlet62. InFIG.2, the gas inlet62is illustrated at the first door13as an example. Gases from the inner space5of the dryer receptacle3may be withdrawn via a gas outlet80. InFIG.2, the gas outlet80is illustrated at the outlet tube31of the outlet system29as an example. The drying process could also be carried out under vacuum.

Volatiles evaporated in the dryer receptacle3during drying of the herbaceous material may be processed. Such volatiles may, for example, comprise flavor compounds evaporated during drying of the herbaceous material, in particular during drying of tobacco material. The volatiles may, for example, carry flavor extracted from the herbaceous material. The volatiles could, for example, comprise aromatic substances or oils. The volatiles could comprise, for example, alkaloids such as nicotine. The volatiles could also comprise pyrazines such as for example: 2-methylpyrazine; 2,5-dimethylpyrazine; 2,6-dimethylpyrazine; 2-ethylpyrazine; 2,3-dimethylpyrazine; 2-ethyl-5-methylpyrazine; 2-ethyl-6-methylpyrazine; 2,3,5-trimethyl Pyrazine; tetramethylpyrazine; 2-ethyl-3,6-dimethylpyrazine; or 2-ethyl-3,5-dimethylpyrazine. Other examples of volatiles include β-ionone; β-damascenone; or acetic acid.

To increase drying efficiency and quality of the resulting products, the herbaceous material inside the dryer receptacle3may be agitated during drying. This may be achieved with vanes49extending from an inner surface51of the dryer receptacle3into the inner space5of the dryer receptacle3. Respective vanes49according to a first exemplary embodiment are illustrated inFIG.3A, which shows the inner surface51of the dryer receptacle3and the vanes49in a sectional view with a sectional plane that is perpendicular to the rotation axis10of the dryer receptacle3.FIG.3Bshows a corresponding view according to a second exemplary embodiment. In the first embodiment shown inFIG.3A, the vanes49have a parallelepiped shape. The vanes49according to the second embodiment shown inFIG.3Bhave curved shapes.

According to both embodiments, the vanes49are, in the cross-section with the sectional plane perpendicular to the rotation axis10of the dryer receptacle3, inclined with respect to the radial direction, which is radial with respect to the rotation axis10. The angle of inclination of the vanes49with respect to the radial direction is illustrated as angle20in the figures. To define the angle, the figures show radius lines30connecting, in the cross-section view, the rotation axis10of the dryer receptacle3with center points of base portions of the vanes49, the base portions being portions of the vanes49where the vanes49meet the inner surface51of the dryer receptacle3. Further, the figures illustrate extension lines40being lines that connect the center points of the base portions of the vanes49with center points of far end portions of the vanes49, the far end portions of the vanes being the portions reaching farthest into the inner space5of the dryer receptacle3.

In the illustrated embodiments, the angles20between the vanes49and the radial direction are the same for each vane49. Preferably, the angle20is lower than 30 degrees. In particular, the angle20can lie between 5 degrees and 25 degrees or more preferably between 5 degrees and 15 degrees.

The arrows inFIGS.3A and3Billustrate the direction of rotation of the dryer receptacle3. As illustrated, the inclination of the vanes49is such that in the sectional plane perpendicular to the rotation axis10of the dryer receptacle3, angles between the vanes49and the inner surface51of one of the dryer receptacle3are larger when measured in the direction of rotation of the dryer receptacle3than when measured against the direction of the rotation of the dryer receptacle3. The angles are in both cases measured starting from the respective vane49and ending at the inner surface51of the dryer receptacle3. The larger angle measured in the direction of rotation of the dryer receptacle3is indicated as angle50in the figures, whereas the smaller angle measured against the direction of rotation of the dryer receptacle3is indicated as60. Angles50and60are again defined referring to the extension lines40of the vanes49. Generally, in case of nonlinear portions of the inner surface51of the dryer receptacle3, the angles50and60may be measured with reference to tangent lines to the inner surface51of the dryer receptacle3at the center of the base portion of the respective vane49.

As can be understood fromFIGS.3A and3B, engagement surfaces53of the vanes49will engage herbaceous material received in the dryer receptacle3, when the dryer receptacle3is rotated about the rotation axis10in the direction of rotation of the dryer receptacle3. The inclination of the vanes49enables the vanes49to better engage the herbaceous material. Further, due to the inclination of the vanes49, pockets55are formed between the vanes49and the inner surface51of the dryer receptacle3. The pockets55can temporarily hold herbaceous material during rotation of the dryer receptacle3. Due to the inclination of the vanes49, the holding time of the herbaceous material in the pockets55is increased, thereby increasing overall agitation in the dryer receptacle3. Further, if the vanes49are heated (see below description), the increased contact time between the inclined vanes49and the herbaceous material increases heating efficiency.

As the vanes49shown inFIG.3Bare curved in the direction of inclination of the vanes49, large quantities of herbaceous material can be picked up by the vanes49. The curvature of the vanes49may also increase contact time between the vanes49and the herbaceous material, as curved vanes49may let the herbaceous material slip later than straight vanes during rotation of the dryer receptacle3.

Preferably, an arch distance between two adjacent vanes49with respect to the rotation axis10is equal to or greater than a height dimension of the vanes49. This can ensure that adjacent vanes49do not too strongly interfere with picking up herbaceous material by the vane49.

As shown inFIGS.2and5, a collector57is provided in the inner space5of the dryer receptacle3at the outlet side11. In the illustrated embodiment, the collector57is integrally formed with the outlet tube31of the outlet system29. However, it is not required that the collector57and the outlet tube31are integrally formed. For example, the collector57could be fixed to the outlet tube31or another structure of the dryer1. The collector56is stationary and does not rotate together with the dryer receptacle3.FIG.4shows a schematic perspective view of the collector57and the outlet duct31. The collector57is channel-shaped and is open in its upper portion. The collector57has at least two sections which are extending in different directions. The collector57can, for example, be essentially U-shaped or essentially V-shaped or essentially UN-shaped. In particular, the collector57may have a center section59forming a bottom of the collector57and two side sections61upwardly extending from opposing ends of the center section59. The distance between the side sections61can increase in a direction away from the center section59(upwards direction). When the dryer receptacle3is rotated about its rotation axis10, herbaceous material inside the dryer receptacle3is agitated. During rotation of the dryer receptacle3, herbaceous material may enter the collector57. In particular, herbaceous material may be agitated and picked up by the vanes49and fall by gravity into the collector57. The divergence of the side sections61of the collector57in the upwards direction leads to a funnel effect funneling herbaceous material falling due to gravity toward the center section59of the collector57.

The collector57constitutes a simple and effective way of collecting herbaceous material in the inner space5of the dryer receptacle. In particular, the collector57can be constituted by or comprise a curved plate defining the center section59and the side sections61.

According to the illustrated embodiment, at least a portion of an upper rim of the collector57defining the top opening of the collector57is slanted downwards. In particular, upper rims of the side sections61of the collector57may be slanted downwards. Herbaceous material falling onto the slanted rim from above may slide down the slanted rim instead of remaining at the rim or sticking to the rim.

FIG.5shows a view on the inner surface of the second door15from inside the dryer receptacle3. As illustrated, the rotation axis10of the dryer receptacle3extends within the collector57. In particular, the collector57extends in parallel to the rotation axis10of the dryer receptacle3. The outlet conveyor37extends through the outlet duct31into the collector57to convey herbaceous material collected in the collector57towards the outlet35.

In the illustrated embodiment, the collector57is asymmetrical with respect to a plane defined by the rotation axis10and a vertical direction. The asymmetric shape of the collector57may facilitate collecting herbaceous material during rotation of the dryer receptacle3. In particular, one of the side sections61of the collector57may be longer than the other side section61of the collector57. The shorter side section61may facilitate entry of the herbaceous material into the collector57. The longer side section61may contribute to holding the herbaceous material in the collector57. Preferably, the dryer receptacle3is rotated such that the shorter side section61is downstream of the longer side section61with respect to the rotation direction of the dryer receptacle3.

The collector57could also be is asymmetrical with respect to the plane defined by the rotation axis10and a vertical direction in other ways. For example, the shapes or the dimensions or the shapes and the dimensions of the side sections61of the collector57could differ from each other. Also, the orientations of the side sections61of the collector57could differ from each other. Alternatively, the collector57could be symmetrical with respect to the plane defined by the rotation axis10and the vertical direction.

As illustrated inFIG.2, a liquid dispersion assembly having two nozzles61is provided. The nozzles61are provided at the ends of the conveyor screw of the inlet conveyor25and the conveyor screw of the outlet conveyor37, respectively. Inside the respective conveyor screw, a channel63is provided for supplying liquid to the nozzle61. The nozzles61are configured to spray liquid inside the inner space5of the dryer receptacle3. During drying of herbaceous material, liquids for treating the herbaceous material may be sprayed through the nozzles61. Further, when the dryer receptacle3is to be cleaned between uses, cleaning liquid can be sprayed by the nozzles61. As the nozzles61rotate, they can reach even spots that are usually difficult to reach for cleaning. The nozzles61may be set to rotate together with the respective conveyor screw. Alternatively, the nozzles61could be decoupled from the conveyor screws. For example, the nozzles61could be rotated by the liquid spraying out of the nozzles61.

To facilitate drying of the herbaceous material, the dryer1comprises a heating system65. The heating system65comprises multiple heating elements, which can comprise wall heating elements67, vane heating elements69, door heating elements71, conveyor heating elements73, and one or more collector heating elements74. The wall heating elements67can be incorporated into the circumferential wall of the main body7of the dryer receptacle3. The vane heating elements69can be incorporated into the vanes49protruding inside the inner space5of the dryer receptacle3. The door heating elements71can be incorporated into the first and second doors13,15of the dryer receptacle3. The conveyor heating elements73can be incorporated into the inlet conveyor25and the outlet conveyor37. The collector heating elements74may be incorporated into the collector57. Wall heating elements67, vane heating elements69, and door heating elements71are illustrated inFIG.2. The conveyor heating elements73and the collector heating elements74are not illustrated inFIG.2for the sake of clarity. Conveyor heating elements73could, for example, be incorporated into the conveyor screw of the inlet conveyor25. Alternatively or additionally, conveyor heating elements73could, for example, be incorporated into the outlet conveyor37. Conveyor heating elements73could also be incorporated into the inlet tube19. Alternatively or additionally, conveyor heating elements73could also be incorporated into the outlet tube31.

The first and second doors13,15and the inlet and outlet conveyors25,37are part of access assemblies providing access to the inner space5of the dryer receptacle3. Heating such access assemblies by the door heating elements71and the conveyor heating elements73facilitates maintaining a certain temperature level in the dryer receptacle3. If only wall heating elements67and vane heating elements69were present, parts of access assemblies, such as the doors13,15or the conveyors25,37might provide space for the formation of lower temperature spots. At lower temperature spots, gaseous material generated during drying of the herbaceous material in the dryer receptacle3could condensate, which could negatively influence drying efficiency and quality of the dried material.

Heating the vanes49with the vane heating elements69incorporated in the vanes49is highly effective, as the vanes49come in direct contact with large amounts of herbaceous material, when agitating the herbaceous material. Further, as the vanes49are inclined, the duration of contact between the herbaceous material and the vanes49is increased. That may increase heating efficiency.

Heating the collector57with the collector heating elements74may contribute to removing residual moisture before the herbaceous material leaves the inner space5of the dryer receptacle3.

The block diagram shown inFIG.6shows a control scheme of the heating system65. The heating elements67,69,71,73,74are grouped into heating sub-systems75, which are controlled independently of each other by a controller78.

According to the illustrated embodiment, five distinct main body heating sub-systems75aare provided. Each of the main body heating sub-systems75acomprises a plurality of wall heating elements67and a plurality of vane heating elements69. An alternative would be to provide separately controlled wall heating sub-assemblies and vane heating sub-assemblies instead of providing main body heating sub-assemblies75acomprising both wall heating elements67and vane heating elements69. As shown inFIG.2, there are five columns of wall heating elements67and five columns of vane heating elements69along the direction of extension of the rotation axis10of the dryer receptacle3. Those correspond to the five main body heating sub-systems75a. This means that, according to the illustrated embodiment, the wall heating elements67and the vane heating elements69are grouped into the main body heating sub-assemblies75aby defining groups of heating elements67,69that lie one behind the other along a direction parallel to the rotation direction A of the dryer receptacle3. Independent control of the main body heating sub-assemblies75aby the controller78allows establishing independently controlled heating zones along the extension direction of the rotation axis10of the dryer receptacle3.

According to the illustrated embodiment, the heating system65further comprises two door heating sub-assemblies75b. Each of the door heating sub-assemblies75bcomprises the door heating elements71incorporated into a corresponding one of the first and second doors13,15. Independent control of the two door heating sub-assemblies75bby the controller78allows, for example, heating the first and second doors13,15to different temperatures. Also, the first and second doors13,15could be heated to the same target temperature, but with different feedback control parameters.

Further, according to the illustrated embodiment, the heating system65comprises two conveyor heating sub-systems75c. The conveyor heating sub-systems75cmay comprise the conveyor heating elements73of a corresponding one of the inlet conveyor25and the outlet conveyor37.

Further, according to the illustrated embodiment, the heating system65comprises a collector heating sub-system75d. The collector heating sub-system75dmay comprise the one or more collector heating elements74.

FIG.6schematically illustrates temperature sensors77distributed at appropriate places at the dryer1to measure temperatures corresponding to respective heating sub-systems75.FIG.6illustrates ten temperature sensors77, one for each of the heating sub-systems75. The temperature sensors77are provided with wireless transmission devices79wirelessly transmitting the respective temperature sensor values to the controller78. Alternatively, there could be a wired connection between the temperature sensors77and the controller78. The controller78controls each of the heating sub-systems75based on an output of the corresponding temperature sensor77. In the illustrated embodiment, the heating sub-systems75are all controlled independently of each other based on the sensing value from the respective temperature sensor77. However, it would also be conceivable to group some or all of the heating sub-systems75to be controlled together or to at least be controlled based on an output of the same temperature sensor77.

Having independently controlled heating sub-assemblies75provides a high level of control over the temperature distribution in the dryer receptacle3during drying of the herbaceous material. Therefore, the drying process can be accurately controlled and adjusted to obtain high-quality products. Depending on the herbaceous material to be treated and on the desired properties of the products to be obtained, different principles of operating the heating sub-systems75are conceivable. For example, the main body heating sub-assemblies75acould be controlled to provide a temperature gradient in the inner space5of the dryer receptacle3along an extension direction of the rotation axis10of the dryer receptacle3. This could, for example, be achieved by using different temperature target values for control of the different main body heating sub-assemblies75a. For example, the temperature gradient could be such that a temperature is higher at the inlet side9of the dryer receptacle3and a temperature is lower at the outlet side11of the dryer receptacle3. Alternatively, the temperature gradient could be established such that the temperature is lower at the inlet side9of the dryer receptacle3and higher at the outlet side11of the dryer receptacle3. A respective temperature difference between the inlet and outlet sides9could be, at least 10 degrees Celsius, at least 20 degrees Celsius, at least 30 degrees Celsius, at least 50 degrees Celsius, at least 100 degrees Celsius, or more than 100 degrees Celsius, for example.

It would also be conceivable to use the same temperature target values for all main body heating sub-assemblies75a, but to use the sensing values from the different temperature sensors77for the respective main body heating sub-assemblies75afor independent control adapted to the characteristics of the main body heating sub-assemblies75a, such as heat capacity, thereby achieving a highly even temperature throughout the longitudinal direction of the dryer receptacle3.

The door heating sub-assemblies75band the conveyor heating sub-assemblies75care preferably controlled to maintain at least a predetermined minimum temperature, which is also called minimum access assembly temperature, at the doors13,15or the inlet and outlet conveyors25,37, respectively. The minimum access assembly temperature could be selected such that the formation of lower temperature spots at the access assembly, in particular at the doors13,15or the conveyors25,37, is prevented. Preventing lower temperature spots may prevent condensation of gaseous material generated during drying of the herbaceous material at such spots.

The door heating sub-assemblies75bis preferably controlled based on different temperature target values for the first door13and the second door15. This could, in particular, be done in combination with a temperature gradient established by appropriately controlling the main body heating sub-assemblies75a.

Temperature target values for the respective heating sub-systems75could be entered by a user via an input device81. Alternatively or additionally, temperature target values for the respective heating sub-systems75could be stored in a memory device83.

FIG.6also illustrates an optional pressure sensor82. The pressure sensor82may be configured to determine a pressure in the inner space5of the dryer receptacle3. If superheated steam is used for heating the inner space5of the dryer receptacle3, a temperature within the inner space5of the dryer receptacle may be deduced from the determined pressure. The pressure determined by the pressure sensor82may be wirelessly transmitted to the controller78and be used for controlling one or more of the heating sub-assemblies75.

InFIG.6, each of the heating sub-systems75comprises an actuator85that is controlled by the controller78to appropriately actuate the respective heating elements67,69,71,73,74. The actuators may, for example, comprise electrical circuitry for supplying resistance heating elements with electrical power or pumps or valves for providing heating elements that are configured as heating fluid lines with appropriately heated fluid.

Further, the controller78may be configured for controlling a driving device90for rotating the dryer receptacle3about the rotation axis10. Preferably, the controller78is configured to control the driving device90to rotate the dryer receptacle3exclusively in one direction of rotation. However, the controller78may also be configured to control the driving device90to change a rotation direction of the dryer receptacle3. In particular, the rotation direction of the dryer receptacle3could be changed at intervals to improve distribution of the herbaceous material within the dryer receptacle3. The controller78may also control the hydraulic cylinder47of the tilting device41.