Drying system

Abstract

A drying system (100) for drying a material, the drying system (100) comprising a container (200) for feeding material from a material inlet (210) at a top of the container (200) to a material outlet (220) at a bottom of the container (200), a dry air inlet (230) at the bottom of the container (200), an air distribution arrangement (400) comprising a plate (410) arranged above the dry air inlet (230), and an agitator arrangement (300), for agitating the material in the container (200), arranged above the plate (410), wherein dry air is arranged to flow from the dry air inlet (230) and around an edge of the plate (410), to dry the material in the container (200).

Description

Technical field

[0001] The present invention relates generally to systems for drying materials, specifically materials having a low bulk density.Background art

[0002] In recent years, organic materials have gained increased focus in the plastic industry, partly attributed to a low carbon footprint. Bio-composites is one example of a new class of organic composite materials. Bio-composites comprise a polymer and an organic particle such as an organic fiber, either as a reinforcing component or for providing other advantageous properties. The organic particle can for example come from a natural source such as forestry or an agricultural source, and examples include materials such as hemp or cellulose. The material properties and behavior of organic particles differ vastly from common reinforcing materials used in the plastic industry today, for example inorganic powders, particles, or fibers, such as nano fibers.

[0003] The field of handling organic materials and organic particles is unexplored and there is a need for innovative solutions in many areas.

[0004] Many challenges with the organic particles are associated with their low bulk density, which is the average density of a volume of many particles and the surrounding air (compared to the density of a single particle). The challenges with a low bulk density are both related to feeding of material and drying of material.

[0005] Feeding low bulk density materials, that is, transporting it in and between various process steps, is not trivial. Since the particles are light as well as surrounded by air, they form a volume which does not easily flow or fall. Furthermore, especially for organic particles, there is an aggravating phenomenon known as bridging. Bridging is a mechanism wherein the particles catch on to each other, which can cause the material to form a lid, or wall, and block the passage of further material.

[0006] Drying low bulk density materials is difficult, many times due to the same reasons that cause problems with feeding the material. The light weight, and surrounding air, makes removal of moisture difficult as there is a high risk of local density variations where moisture pockets can form. A prerequisite for subsequent processing steps, such as compounding, is low or zero retained water in the organic particles. In other words, it should be as dry as possible, preferably below 2% moisture. As such, the organic particles need to be dried before they can be used in a compounding process. Existing systems for drying materials with low bulk density are not suitable for organic materials and do not provide sufficient drying for a subsequent compounding process. The existing systems which may be considered may comprise a drying chamber in which the material is contained during drying. The material is removed from the chamber after it has been dried.

[0007] In other technical fields, which do not relate to organic materials, drying chambers may also provide for a flow of material from an inlet to an outlet, wherein the material is dried on the way through the chamber. However, such prior art solutions often have internal obstructions, such as dry air pipes extending from the top to the bottom or other types of drying equipment extending into the internal space of the silo. These obstructions may especially cause problems in fiber materials, as they may contribute to bridging.

[0008] For example, in prior art, drying chambers provide dry air from above, and are constructed with a pipe extending down from the top of the chamber, ending in a funnel. The dry air exiting the pipe flows around the edges of the funnel and up through the chamber. Alternatively, some prior art silos have dry air pipes extending horizontally into the chamber. To prevent material getting caught on the horizontal pipes, they may be provided with angled roofs to facilitate the flow of material around the horizontal pipes.

[0009] As such there is need for improved solutions for drying low bulk density materials, such as organic materials.Summary of invention

[0010] An object of the present invention is to overcome at least some of the problems outlined above.

[0011] According to a first aspect of the disclosure there is provided a system for drying a material, the system comprising a container for feeding material from a material inlet at a top of the container to a material outlet at a bottom of the container, a dry air inlet at the bottom of the container, an air distribution arrangement comprising a plate arranged above the dry air inlet, and an agitator arrangement, for agitating the material in the container, arranged above the plate, wherein dry air is arranged to flow from the dry air inlet and around an edge of the plate, to dry the material in the container.

[0012] The effect of the present disclosure is a homogenous and efficient drying of the material in the system. By means of the air distribution arrangement combined with agitation of the material, accumulation of moisture in moisture pockets can be prevented.

[0013] Having the dry air inlet at the bottom provides that air efficiently dries all the material in the container, from the bottom up. Having the dry air inlet at the bottom also provides that agitation and drying can be provided in the same system. Drying equipment in prior art which for example extends from the top of the container, or from the sides, is not easily combined with a system for agitation. According to the present disclosure, combined agitation and drying becomes possible by arranging the dry air inlet at the bottom. As such, it is also possible to provide a space efficient system.

[0014] The agitation has several functions. By agitating the material in the container, more material comes into contact with dry air and the drying is thus more efficient. Furthermore, the formation of marsh trails by the dry air is prevented. Furthermore, agitating the material promotes the movement from the material inlet to the material outlet, as the agitation breaks up networks formed for example by agglomeration or bridging, thereby enhancing the efficiency of the system. There is particularly a need to facilitate the flow of material when the material has a low bulk density, as the force of gravity may not be sufficient to move the material to the material outlet. Agitation of the material also helps to decrease density variations where moisture can otherwise accumulate, thereby improving the drying effect of the system.

[0015] The dry air inlet works in conjunction with the air distribution arrangement to provide a flow of dry air through the material in the container and efficiently remove moisture from the material. Guiding the dry air around the edge of the plate promotes a laminar flow of dry air through the material above the plate, the laminar flow being in an upwards, essentially vertical direction through the container. This prevents the air from forming marsh trails, or even highways, through the material. Instead, the air spreads out evenly such that more material comes into contact with the air.

[0016] Advantageously, the system can be arranged as a process step in a continuous process, since the material is arranged to move from the material inlet to the material outlet. The present system provides that the material does not clog or block said movement through the system. Since the system provides for continuous feeding of material, it is crucial that the drying is efficient, and that the material has reached a desired low moisture level upon exit from the system, compared to a static drying system, where the material can simply be kept in the container until it is sufficiently dry.

[0017] In an exemplary embodiment, the air distribution arrangement further comprises a distribution means extending from a bottom major surface of the plate, through which the dry air is guided before passing around the edge of the plate.

[0018] The distribution means provides that as much air as possible from the air from the dry air inlet is guided around the edge of the plate and spreads evenly around the edge.

[0019] In an exemplary embodiment, the distribution means comprises a perforated flange extending from the bottom major surface of the plate, the perforated flange forming a closed loop on the bottom major surface.

[0020] To promote a close to laminar flow of dry air, the air is guided through the perforated flange. The perforations distribute the air before it flows around the edge of the plate.

[0021] In an exemplary embodiment, the air distribution arrangement is carried by the perforated flange which rests on the bottom of the container.

[0022] This provides that essentially all the air from the dry air inlet at the bottom of the container passes through the perforated flange.

[0023] In an exemplary embodiment, the plate is arranged essentially horizontally in the container.

[0024] In an exemplary embodiment, the plate has an essentially oval shape, the major semiaxis of which is essentially equal to half of a radius of the container.

[0025] The size and shape of the plate determines where the dry air comes into contact with the material in the container. As such, the plate cannot have an extension covering a to great area of the container, as the air would then only flow up along the walls of the container. Furthermore, the plate cannot be too small, as the air would only flow through a center of the container. Other shapes of plate or contemplated in alternative embodiments, which also fulfill the above mentioned restrictions.

[0026] In an exemplary embodiment, at least a section of an edge of the plate is slanting towards the bottom of the container. In an exemplary embodiment, the slanting section is a part of the edge being folded towards the bottom of the container.

[0027] Having the edge of the plate slanting downwards provides that material can flow pass the plate, via the slanting section, more easily on the way to the material outlet. However, the flow of air from the dry air inlet needs to be considered. As such, in one embodiment, there are openings provided in the slanting section of the edge, to allow air to pass through.

[0028] In an exemplary embodiment, the material outlet of the container is arranged below the slanting section of the edge.

[0029] The material flows more easily around the slanting section of the edge. As such, it is advantageous to position the material outlet below said slanting section.

[0030] In an exemplary embodiment, the agitator arrangement comprises a rotation shaft extending vertically from the top of the container towards the plate, and at least one agitation wing extending essentially horizontally from the rotation shaft, wherein the at least one agitation wing is arranged to rotate above the plate.

[0031] According to a second aspect of the disclosure, there is provided a method for drying a material in a system for drying, the method comprising providing a continuous feeding of material from a material inlet at a top of the system to a material outlet at a bottom of the system, and providing a flow of dry air from the bottom of the system, wherein the flow of dry air, after entering the system, passes an air distribution arrangement before reaching the material to be dried, the air distribution arrangement comprising a plate around the edge of which the dry air is arranged to flow.

[0032] In an exemplary embodiment, the material is an organic material, such as an organic fiber material.

[0033] In an exemplary embodiment, the method comprises agitating the material in the system, the agitation taking place at a position above the air distribution arrangement.Brief description of drawings

[0034] The invention is now described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 displays a perspective view of the drying system according to the disclosure. Fig. 2 displays a cross-sectional view of the drying system, illustrating the material inlet, material outlet, the dry air distribution arrangement and agitator arrangement. Fig. 3 displays a view of the bottom of the container of the drying system. Fig. 4 displays a perspective view of the agitator arrangement, showing the rotation axis and rotation wings. Figs. 5a and 5b display a detailed view of the dry air distribution arrangement, including the plate and distribution means, and illustrating the flow of dry air through the distribution means and around the plate into the material in the drying system. Fig. 6 displays a top view of the dry air distribution arrangement, illustrating the circumferential edge and slanting section. Fig. 7 displays an alternative embodiment of the dry air distribution arrangement with a circular shape. Fig. 8 displays a view of the bottom of the drying system showing the dry air distribution arrangement. Fig. 9 displays a view of the dry air distribution arrangement, highlighting the perforations in the flange. Fig. 10 displays a material handling system of which the drying system forms a part. Description of embodiments

[0035] In the following, a detailed description of a system for drying a material, and a method for drying a material, is described. In the figures, like reference numerals designate identical or corresponding elements throughout the figures. It will be appreciated that these figures are for illustration only and do not in any way restrict the scope of the present disclosure.

[0036] With reference to Fig. 1 and Fig. 2 there is displayed a drying system 100 according to the disclosure. The drying system 100 generally comprises a container 200, an agitator arrangement 300 and an air distribution arrangement 400. The drying system 100 is preferably part of a material handling system, such as for handling material components for composite materials, such as bio-composites. An example of such a material handling system is described below with reference to Fig. 10.

[0037] The container 200 is the primary structure of the drying system 100. It is designed to contain and handle material in a controlled environment. The container 200 comprises several components that facilitate the entry, transport, and exit of material during drying of the material therein. These components comprise a material inlet 210, a material outlet 220, a dry air inlet 230, an air outlet (not shown), a feed screw 240 below a floor 250 of the container 200. The container 200 may also be referred to as a silo.

[0038] The material inlet 210 is located at the top of the container 200 and serves as the entry point for the material into the container 200. The position of the material inlet 210 at the top provides that the material moves to the material outlet 220 at the bottom assisted by gravity. In some embodiments, the material inlet 210 comprises a gate or valve to control the flow of material into the container 200. The material inlet 210 may also comprise a dust collection system to minimize the release of dust into the environment during the loading process. In the embodiment displayed in Fig.1 and Fig. 2, the material inlet 210 in located at the uppermost point of the container 200. Alternatively, the material inlet 210 may be arranged offset from the uppermost point of the container 200, as long as the material inlet 210 is located at an upper portion of the container 200.

[0039] With reference to Fig.3 there is displayed the floor 250 of the container 200. The floor 250 forms the base of the container 200. The floor 250 preferably comprises the dry air inlet 230 and the material outlet 220. In Fig. 3, the dry air inlet 230 and material outlet 220 are represented by openings in the floor 250 of the container 200. In one embodiment, the air distribution arrangement 400 rests on the floor 250, and the floor 250 thus supports the air distribution arrangement 400.

[0040] The dry air inlet 230 allows dry air to enter the container 200, which then flows via the air distribution arrangement 400 before reaching the material in the container 200. The dry air inlet 230 is located at the bottom of the drying system 100, preferably in the floor 250 of the container 200. The dry air removes moisture from the material, which is made more efficiently by distributing the dry air evenly throughout the material by means of the air distribution arrangement 400. The dry air inlet 230 is located below the air distribution arrangement 400, such that the dry air is guided to pass the air distribution arrangement 400 before reaching the material in the container 200. In Fig. 3, the dry air inlet 230 is represented by two openings in the floor 250 of the container 200. In alternative embodiments, there may be only one or several openings in the floor 250 of the container 200.

[0041] The dry air inlet 230 may in turn be connected to a dry air duct 231 for inflow of dry air. In some configurations, the dry air inlet 230 and / or the air duct 231 may comprise a filter or a dust collection system to prevent dust or unwanted particles entering the drying system 100.

[0042] The material outlet 220 is located at the bottom of the container 200 and serves as the exit point for the material from the container 200. The material outlet 220 allows the material to exit the container 200 by gravity and preferably also with the help from the feed screw 240.The container 200 may comprise one or several material outlets 220. The material outlet 220 is preferably one or several openings in the floor 250 of the container 200. In the embodiment displayed in Fig. 3, the container 200 comprises two material outlets 220. Preferably, an opening in the floor 250 of the container 200 corresponding to a material outlet 220, is significantly larger than an opening corresponding to a dry air inlet 230. The material outlet may have an extended or elongated shape, such as an oval.

[0043] The feed screw 240 is a component of the container 200 that is used to transport the material away from the container 200. The feed screw 240 is arranged below the floor 250 of the container 200 and is positioned below the material outlet 220. The feed screw 240 is arranged in a screw shaft 241 below the floor 250 of the container 200, preferably attached to or suspended from the floor 250 of the container 200. The feed screw 240 is designed to move the material from the material outlet 220 to a location outside the container 200. The feed screw 240 operates by rotating, which causes the material to move along the screw and out of the container 200. In one embodiment, the feed screw 240 is a shaftless feed screw 240, meaning it has no physical center axis. Shaftless feed screws 240 allow for efficient transport of a wide range of materials, including those that have a low bulk density and thus difficult to handle. The feed screw 240 is preferably powered by an electric motor and the rotation speed of the feed screw 240 can be controlled to adjust the rate of material discharge from the container 200. In the embodiment displayed with reference to Figs. 1-3, the drying system 100 comprises two feed screws 240 in a respective screw shaft 241, arranged essentially parallel to each other and arranged below a respective material outlet 220.

[0044] The air outlet (not shown) is located at the top of the container 200. The air outlet serves a function in the operation of the container 200 by allowing humid air to exit the container 200 after passing through the material in the container 200. The air outlet may help to maintain the pressure balance within the container 200 for efficient operation of the container 200. In some configurations, the air outlet may comprise a filter or a dust collection system to minimize the release of dust into the environment during the discharge of air from the container 200.

[0045] The agitator arrangement 300 displayed in Fig. 4 is designed to agitate the material in the container 200. The agitator arrangement 300 comprises a rotation axis 310 and agitation wings 320 that are used to agitate the material. The agitator arrangement 300 is arranged to agitate the material above the air distribution arrangement 400. As such, the agitation takes place above the air distribution arrangement 400.

[0046] With reference to Fig. 4, the rotation axis 310 is a component of the agitator arrangement 300 that is designed to transfer rotational movement to the agitation wings 320 of the agitator arrangement 300. In one embodiment, the rotation axis 310 extends from the top of the container 200 to near the air distribution arrangement 400. In an alternative embodiment, the rotation axis 310 extends through the air distribution arrangement 400. In one embodiment, the rotation axis 310 additionally extends through the floor 250 of the container 200. The rotation axis 310 is connected to a drive unit that provides the rotational movement. The rotation axis 310 is designed to withstand the forces generated during the agitation of the material and to ensure the smooth and efficient operation of the agitator arrangement 300.

[0047] The agitation wings 320 are components of the agitator arrangement 300 that are used to agitate the material in the container 200. The agitation wings 320 are arranged above the air distribution arrangement 400. The agitation wings 320 are preferably made of metal, which provides rigidity and strength. The agitation wings 320 are more preferably steel. The agitation wings 320 are connected to the rotation axis 310 and rotate with the rotation axis 310 to agitate the material. The agitation wings 320 each comprise a horizontal portion. The horizontal portion of the agitation wings 320 comprises a proximal end connected to the rotation axis 310, and a distal end extending towards the wall of the container 200. The agitation wings 320, and thus the horizontal portions, preferably extend essentially parallel to an upper surface of the air distribution arrangement 400. In one embodiment, the horizontal portion has a length that is near the length of the radius of the container 200. The horizontal portion is designed to agitate the material in the container 200 in a manner that facilitates the flow of material towards the material outlet 220. The agitation wings 320 are designed to ensure efficient agitation of the material and to minimize the formation of agglomerated material or moisture pockets in the material in the container 200. In one embodiment, the agitator arrangement 300 comprises only one agitation wing. In one embodiment, the agitator arrangement 300 comprises at least two agitation wings 320 to enhance the agitation of the material. The design and number of wings may be determined based on the material in the container 200.

[0048] With reference to Fig. 5a and Fig. 5b, the air distribution arrangement 400 is displayed. The air distribution arrangement 400 comprises a plate 410. The plate 410 guides the flow of dry air in the container 200 in a manner that promotes even distribution of dry air throughout the material. The plate 410 comprises an upper major surface 411, a bottom major surface 412, and a circumferential edge 413. The circumferential edge 413 defines the circumference of the plate 410, and the air distribution arrangement 400 guides the flow of dry air around the circumferential edge 413 into the material in the container 200. Because the air must pass around the circumferential edge 413, the flow of air through the material becomes close to laminar in an upwards direction through the container 200. The plate 410 is preferably made of a strong and durable material, such as metal, preferably steel, to ensure its longevity and reliability. In one embodiment, plate 410 has a thickness of 3-10 mm, preferably of 3-7 mm, more preferably 3-5 mm, most preferably 4 mm. Having a thin plate 410 provides that it can be easily removed for example during cleaning or repair.

[0049] The air distribution arrangement 400 is designed to distribute dry air in the container 200. When dry air enters through the dry air inlet 230 at the bottom of the container 200, the air is guided in the direction of the arrows displayed in Fig. 5b. Guiding the dry air around the edge of the plate 410 promotes a laminar flow of dry air through the material above the plate 410, the laminar flow being in an upwards, essentially vertical direction through the container 200.

[0050] In the displayed embodiments, the plate 410 comprises two halves, which is visualized by a lengthwise joint. The possibility to separate the plate 410 in two halves facilitates assembly of the plate 410 in the container 200, as the plate 410 can be installed and removed in sections. In alternative embodiments, the plate 410 is formed in one piece. In one embodiment, the plate 410 comprises a central hole through which the rotation axis 310 of the agitator arrangement 300 may extend. In such an embodiment it is especially beneficial to have the plate 410 provided in two halves, as installation of the plate 410 around the rotation axis 310 is facilitated.

[0051] In the embodiments displayed in the figures, the circumferential edge 413 comprises a slanting section 414. The slanting section 414 is angled downwards towards the bottom of the container 200. The slanting section 414 is preferably positioned vertically above the material outlet 220. The slanting section 414 provides that the material flowing towards the material outlet 220 is guided towards the material outlet 220. The slanting section 414 furthermore provides that the material is not caught on the circumferential edge 413 of the dry air distribution arrangement 400 or, as the case may be, forms piles of material on the circumferential edge 413. In one embodiment, the slanting section 414 constitutes a minority of the circumferential edge 413, such that dry air can easily flow around the remainder of the circumferential edge 413. In one embodiment, the slanting section 414 comprises one or several passageways for the dry air, for example perforations 421, or the circumferential edge 413 may comprise several shorter slanting sections 414 arranged at a distance from each other such that dry air may pass therebetween. In one embodiment, the circumferential edge 413 comprises at least two slanting sections 414. In one embodiment, the container 200 comprises two material outlets 220 to facilitate the efficient and controlled discharge of material from the container 200, in which embodiment the circumferential edge 413 comprises two slanting sections 414 to be arranged above the material outlets 220. In one example, the plate 410 has an oval shape, and two slanting sections 414 are arranged opposite each other on the two longer sides. In one example, the plate 410 has an oval shape, and two slanting sections 414 are arranged on points of the circumferential edge 413 corresponding to a minor axis. The slanting section 414 may be manufactured by bending or folding a section of the circumferential edge 413. Alternatively, the slanting section 414 may be manufactured in other manners such as by attaching an additional piece of metal plate 410 to the circumferential edge 413, for example by welding, wherein the additional piece of metal plate 410 is attached at a downwards angle in relation to the plate 410.

[0052] Fig. 6 displays the air distribution arrangement 400 from above. In the embodiment displayed in Fig. 6, the plate 410 has an oval shape. In the context of the present disclosure, an oval shape should not be strictly construed according to the mathematical definition of an ellipse, but also encompasses shapes for example having two essentially parallel sides connected by two semi-circles. As such, a major axis of the plate should be understood as the distance between the two most widely separated points of the circumferential edge 413, and when reference is made to a major semiaxis, this should be understood as half this distance. In one embodiment, the major semiaxis of the oval plate 410 is essentially equal to half of a radius of the container 200. The oval shape contributes to the even distribution of dry air, as the dry air comes into contact with the material in the container 200 at different positions in relation to a radius of the container 200.

[0053] In the alternative embodiment displayed in Fig. 7, the plate 410 has a circular shape. In one embodiment, the radius of the circular plate 410 is essentially equal to half of a radius of the container 200.

[0054] Turning now to Fig. 8, the air distribution arrangement 400 is positioned above the dry air inlet 230, the plate 410 having an essentially horizontal extension in the container 200. The air distribution arrangement 400 is preferably positioned close to the floor 250 of the container 200. In one embodiment, the air distribution arrangement 400 rests on the floor 250 of the container 200. In one embodiment, the air distribution arrangement 400 comprises means for arranging the air distribution arrangement 400 at a predetermined distance above the floor 250, such as legs.

[0055] The air distribution arrangement 400 preferably comprises a distribution means 420 designed to additionally enhance the even distribution of dry air in the container 200. The distribution means 420 is arranged below the plate 410 of the dry air distribution arrangement 400. In one embodiment, the distribution means 420 is arranged between the floor 250 and the plate 410 in a way such that air from the dry air inlet 230 only can escape through the distribution means 420. To this end, the distribution means 420 comprises openings or perforations or mesh-like material for the dry air to escape through. The air distribution means 420 is preferably made of a strong and durable material, such as metal, to ensure its longevity and reliability.

[0056] In the embodiment displayed with reference to Fig. 9, the distribution means 420 comprises a perforated flange extending from the bottom major surface 412 of the plate 410. The perforated flange is positioned on the bottom major surface 412 at a predetermined distance from the circumferential edge 413. The perforated flange preferably forms a closed loop on the bottom major surface 412. The perforated flange preferably has a shape which mirrors the circumference of the plate 410. In one embodiment, the air distribution arrangement 400 rests on the floor 250 of the container 200, specifically on the distribution means 420. In one embodiment, the air distribution arrangement 400 rests on the perforated flange and the dry air inlet 230 is arranged within the closed loop of the perforated flange, such that dry air is guided through the perforated flange. In other words, the closed loop is arranged to surround the dry air inlet 230.

[0057] The perforated flange comprises perforations 421 through which dry air from the dry air inlet 230 flows. The perforations 421 are preferably arranged side by side at even distances from each other along the flange. The perforations 421 may for example be round, slit-shaped, or keyhole-shaped.

[0058] With reference to Fig. 10, there is displayed a material handling system, of which the present drying system 100 forms a part. The material handling system transports material from the drying system 100 to a subsequent processing step, such as a further drying step. The material handling system is preferably arranged in connection to a compounding extruder, for example for compounding of bio-composites. The material handling system may comprise a plurality of the drying system 100, for example for different materials to be mixed in subsequent processing steps.

[0059] Preferred embodiments of a drying system have been disclosed above. However, a person skilled in the art realizes that this can be varied within the scope of the appended claims without departing from the inventive idea.

[0060] All the described alternative embodiments above or parts of an embodiment can be freely combined or employed separately from each other without departing from the inventive idea as long as the combination is not contradictory.

Examples

Embodiment Construction

[0035]In the following, a detailed description of a system for drying a material, and a method for drying a material, is described. In the figures, like reference numerals designate identical or corresponding elements throughout the figures. It will be appreciated that these figures are for illustration only and do not in any way restrict the scope of the present disclosure.

[0036]With reference to Fig. 1 and Fig. 2 there is displayed a drying system 100 according to the disclosure. The drying system 100 generally comprises a container 200, an agitator arrangement 300 and an air distribution arrangement 400. The drying system 100 is preferably part of a material handling system, such as for handling material components for composite materials, such as bio-composites. An example of such a material handling system is described below with reference to Fig. 10.

[0037]The container 200 is the primary structure of the drying system 100. It is designed to contain and handle material in a con...

Technical field

[0001] The present invention relates generally to systems for drying materials, specifically materials having a low bulk density.Background art

[0002] In recent years, organic materials have gained increased focus in the plastic industry, partly attributed to a low carbon footprint. Bio-composites is one example of a new class of organic composite materials. Bio-composites comprise a polymer and an organic particle such as an organic fiber, either as a reinforcing component or for providing other advantageous properties. The organic particle can for example come from a natural source such as forestry or an agricultural source, and examples include materials such as hemp or cellulose. The material properties and behavior of organic particles differ vastly from common reinforcing materials used in the plastic industry today, for example inorganic powders, particles, or fibers, such as nano fibers.

[0003] The field of handling organic materials and organic particles is unexplored and there is a need for innovative solutions in many areas.

[0004] Many challenges with the organic particles are associated with their low bulk density, which is the average density of a volume of many particles and the surrounding air (compared to the density of a single particle). The challenges with a low bulk density are both related to feeding of material and drying of material.

[0005] Feeding low bulk density materials, that is, transporting it in and between various process steps, is not trivial. Since the particles are light as well as surrounded by air, they form a volume which does not easily flow or fall. Furthermore, especially for organic particles, there is an aggravating phenomenon known as bridging. Bridging is a mechanism wherein the particles catch on to each other, which can cause the material to form a lid, or wall, and block the passage of further material.

[0006] Drying low bulk density materials is difficult, many times due to the same reasons that cause problems with feeding the material. The light weight, and surrounding air, makes removal of moisture difficult as there is a high risk of local density variations where moisture pockets can form. A prerequisite for subsequent processing steps, such as compounding, is low or zero retained water in the organic particles. In other words, it should be as dry as possible, preferably below 2% moisture. As such, the organic particles need to be dried before they can be used in a compounding process. Existing systems for drying materials with low bulk density are not suitable for organic materials and do not provide sufficient drying for a subsequent compounding process. The existing systems which may be considered may comprise a drying chamber in which the material is contained during drying. The material is removed from the chamber after it has been dried.

[0007] In other technical fields, which do not relate to organic materials, drying chambers may also provide for a flow of material from an inlet to an outlet, wherein the material is dried on the way through the chamber. However, such prior art solutions often have internal obstructions, such as dry air pipes extending from the top to the bottom or other types of drying equipment extending into the internal space of the silo. These obstructions may especially cause problems in fiber materials, as they may contribute to bridging.

[0008] For example, in prior art, drying chambers provide dry air from above, and are constructed with a pipe extending down from the top of the chamber, ending in a funnel. The dry air exiting the pipe flows around the edges of the funnel and up through the chamber. Alternatively, some prior art silos have dry air pipes extending horizontally into the chamber. To prevent material getting caught on the horizontal pipes, they may be provided with angled roofs to facilitate the flow of material around the horizontal pipes.

[0009] As such there is need for improved solutions for drying low bulk density materials, such as organic materials.Summary of invention

[0010] An object of the present invention is to overcome at least some of the problems outlined above.

[0011] According to a first aspect of the disclosure there is provided a system for drying a material, the system comprising a container for feeding material from a material inlet at a top of the container to a material outlet at a bottom of the container, a dry air inlet at the bottom of the container, an air distribution arrangement comprising a plate arranged above the dry air inlet, and an agitator arrangement, for agitating the material in the container, arranged above the plate, wherein dry air is arranged to flow from the dry air inlet and around an edge of the plate, to dry the material in the container.

[0012] The effect of the present disclosure is a homogenous and efficient drying of the material in the system. By means of the air distribution arrangement combined with agitation of the material, accumulation of moisture in moisture pockets can be prevented.

[0013] Having the dry air inlet at the bottom provides that air efficiently dries all the material in the container, from the bottom up. Having the dry air inlet at the bottom also provides that agitation and drying can be provided in the same system. Drying equipment in prior art which for example extends from the top of the container, or from the sides, is not easily combined with a system for agitation. According to the present disclosure, combined agitation and drying becomes possible by arranging the dry air inlet at the bottom. As such, it is also possible to provide a space efficient system.

[0014] The agitation has several functions. By agitating the material in the container, more material comes into contact with dry air and the drying is thus more efficient. Furthermore, the formation of marsh trails by the dry air is prevented. Furthermore, agitating the material promotes the movement from the material inlet to the material outlet, as the agitation breaks up networks formed for example by agglomeration or bridging, thereby enhancing the efficiency of the system. There is particularly a need to facilitate the flow of material when the material has a low bulk density, as the force of gravity may not be sufficient to move the material to the material outlet. Agitation of the material also helps to decrease density variations where moisture can otherwise accumulate, thereby improving the drying effect of the system.

[0015] The dry air inlet works in conjunction with the air distribution arrangement to provide a flow of dry air through the material in the container and efficiently remove moisture from the material. Guiding the dry air around the edge of the plate promotes a laminar flow of dry air through the material above the plate, the laminar flow being in an upwards, essentially vertical direction through the container. This prevents the air from forming marsh trails, or even highways, through the material. Instead, the air spreads out evenly such that more material comes into contact with the air.

[0016] Advantageously, the system can be arranged as a process step in a continuous process, since the material is arranged to move from the material inlet to the material outlet. The present system provides that the material does not clog or block said movement through the system. Since the system provides for continuous feeding of material, it is crucial that the drying is efficient, and that the material has reached a desired low moisture level upon exit from the system, compared to a static drying system, where the material can simply be kept in the container until it is sufficiently dry.

[0017] In an exemplary embodiment, the air distribution arrangement further comprises a distribution means extending from a bottom major surface of the plate, through which the dry air is guided before passing around the edge of the plate.

[0018] The distribution means provides that as much air as possible from the air from the dry air inlet is guided around the edge of the plate and spreads evenly around the edge.

[0019] In an exemplary embodiment, the distribution means comprises a perforated flange extending from the bottom major surface of the plate, the perforated flange forming a closed loop on the bottom major surface.

[0020] To promote a close to laminar flow of dry air, the air is guided through the perforated flange. The perforations distribute the air before it flows around the edge of the plate.

[0021] In an exemplary embodiment, the air distribution arrangement is carried by the perforated flange which rests on the bottom of the container.

[0022] This provides that essentially all the air from the dry air inlet at the bottom of the container passes through the perforated flange.

[0023] In an exemplary embodiment, the plate is arranged essentially horizontally in the container.

[0024] In an exemplary embodiment, the plate has an essentially oval shape, the major semiaxis of which is essentially equal to half of a radius of the container.

[0025] The size and shape of the plate determines where the dry air comes into contact with the material in the container. As such, the plate cannot have an extension covering a to great area of the container, as the air would then only flow up along the walls of the container. Furthermore, the plate cannot be too small, as the air would only flow through a center of the container. Other shapes of plate or contemplated in alternative embodiments, which also fulfill the above mentioned restrictions.

[0026] In an exemplary embodiment, at least a section of an edge of the plate is slanting towards the bottom of the container. In an exemplary embodiment, the slanting section is a part of the edge being folded towards the bottom of the container.

[0027] Having the edge of the plate slanting downwards provides that material can flow pass the plate, via the slanting section, more easily on the way to the material outlet. However, the flow of air from the dry air inlet needs to be considered. As such, in one embodiment, there are openings provided in the slanting section of the edge, to allow air to pass through.

[0028] In an exemplary embodiment, the material outlet of the container is arranged below the slanting section of the edge.

[0029] The material flows more easily around the slanting section of the edge. As such, it is advantageous to position the material outlet below said slanting section.

[0030] In an exemplary embodiment, the agitator arrangement comprises a rotation shaft extending vertically from the top of the container towards the plate, and at least one agitation wing extending essentially horizontally from the rotation shaft, wherein the at least one agitation wing is arranged to rotate above the plate.

[0031] According to a second aspect of the disclosure, there is provided a method for drying a material in a system for drying, the method comprising providing a continuous feeding of material from a material inlet at a top of the system to a material outlet at a bottom of the system, and providing a flow of dry air from the bottom of the system, wherein the flow of dry air, after entering the system, passes an air distribution arrangement before reaching the material to be dried, the air distribution arrangement comprising a plate around the edge of which the dry air is arranged to flow.

[0032] In an exemplary embodiment, the material is an organic material, such as an organic fiber material.

[0033] In an exemplary embodiment, the method comprises agitating the material in the system, the agitation taking place at a position above the air distribution arrangement.Brief description of drawings

[0034] The invention is now described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 displays a perspective view of the drying system according to the disclosure. Fig. 2 displays a cross-sectional view of the drying system, illustrating the material inlet, material outlet, the dry air distribution arrangement and agitator arrangement. Fig. 3 displays a view of the bottom of the container of the drying system. Fig. 4 displays a perspective view of the agitator arrangement, showing the rotation axis and rotation wings. Figs. 5a and 5b display a detailed view of the dry air distribution arrangement, including the plate and distribution means, and illustrating the flow of dry air through the distribution means and around the plate into the material in the drying system. Fig. 6 displays a top view of the dry air distribution arrangement, illustrating the circumferential edge and slanting section. Fig. 7 displays an alternative embodiment of the dry air distribution arrangement with a circular shape. Fig. 8 displays a view of the bottom of the drying system showing the dry air distribution arrangement. Fig. 9 displays a view of the dry air distribution arrangement, highlighting the perforations in the flange. Fig. 10 displays a material handling system of which the drying system forms a part. Description of embodiments

[0035] In the following, a detailed description of a system for drying a material, and a method for drying a material, is described. In the figures, like reference numerals designate identical or corresponding elements throughout the figures. It will be appreciated that these figures are for illustration only and do not in any way restrict the scope of the present disclosure.

[0036] With reference to Fig. 1 and Fig. 2 there is displayed a drying system 100 according to the disclosure. The drying system 100 generally comprises a container 200, an agitator arrangement 300 and an air distribution arrangement 400. The drying system 100 is preferably part of a material handling system, such as for handling material components for composite materials, such as bio-composites. An example of such a material handling system is described below with reference to Fig. 10.

[0037] The container 200 is the primary structure of the drying system 100. It is designed to contain and handle material in a controlled environment. The container 200 comprises several components that facilitate the entry, transport, and exit of material during drying of the material therein. These components comprise a material inlet 210, a material outlet 220, a dry air inlet 230, an air outlet (not shown), a feed screw 240 below a floor 250 of the container 200. The container 200 may also be referred to as a silo.

[0038] The material inlet 210 is located at the top of the container 200 and serves as the entry point for the material into the container 200. The position of the material inlet 210 at the top provides that the material moves to the material outlet 220 at the bottom assisted by gravity. In some embodiments, the material inlet 210 comprises a gate or valve to control the flow of material into the container 200. The material inlet 210 may also comprise a dust collection system to minimize the release of dust into the environment during the loading process. In the embodiment displayed in Fig.1 and Fig. 2, the material inlet 210 in located at the uppermost point of the container 200. Alternatively, the material inlet 210 may be arranged offset from the uppermost point of the container 200, as long as the material inlet 210 is located at an upper portion of the container 200.

[0039] With reference to Fig.3 there is displayed the floor 250 of the container 200. The floor 250 forms the base of the container 200. The floor 250 preferably comprises the dry air inlet 230 and the material outlet 220. In Fig. 3, the dry air inlet 230 and material outlet 220 are represented by openings in the floor 250 of the container 200. In one embodiment, the air distribution arrangement 400 rests on the floor 250, and the floor 250 thus supports the air distribution arrangement 400.

[0040] The dry air inlet 230 allows dry air to enter the container 200, which then flows via the air distribution arrangement 400 before reaching the material in the container 200. The dry air inlet 230 is located at the bottom of the drying system 100, preferably in the floor 250 of the container 200. The dry air removes moisture from the material, which is made more efficiently by distributing the dry air evenly throughout the material by means of the air distribution arrangement 400. The dry air inlet 230 is located below the air distribution arrangement 400, such that the dry air is guided to pass the air distribution arrangement 400 before reaching the material in the container 200. In Fig. 3, the dry air inlet 230 is represented by two openings in the floor 250 of the container 200. In alternative embodiments, there may be only one or several openings in the floor 250 of the container 200.

[0041] The dry air inlet 230 may in turn be connected to a dry air duct 231 for inflow of dry air. In some configurations, the dry air inlet 230 and / or the air duct 231 may comprise a filter or a dust collection system to prevent dust or unwanted particles entering the drying system 100.

[0042] The material outlet 220 is located at the bottom of the container 200 and serves as the exit point for the material from the container 200. The material outlet 220 allows the material to exit the container 200 by gravity and preferably also with the help from the feed screw 240.The container 200 may comprise one or several material outlets 220. The material outlet 220 is preferably one or several openings in the floor 250 of the container 200. In the embodiment displayed in Fig. 3, the container 200 comprises two material outlets 220. Preferably, an opening in the floor 250 of the container 200 corresponding to a material outlet 220, is significantly larger than an opening corresponding to a dry air inlet 230. The material outlet may have an extended or elongated shape, such as an oval.

[0043] The feed screw 240 is a component of the container 200 that is used to transport the material away from the container 200. The feed screw 240 is arranged below the floor 250 of the container 200 and is positioned below the material outlet 220. The feed screw 240 is arranged in a screw shaft 241 below the floor 250 of the container 200, preferably attached to or suspended from the floor 250 of the container 200. The feed screw 240 is designed to move the material from the material outlet 220 to a location outside the container 200. The feed screw 240 operates by rotating, which causes the material to move along the screw and out of the container 200. In one embodiment, the feed screw 240 is a shaftless feed screw 240, meaning it has no physical center axis. Shaftless feed screws 240 allow for efficient transport of a wide range of materials, including those that have a low bulk density and thus difficult to handle. The feed screw 240 is preferably powered by an electric motor and the rotation speed of the feed screw 240 can be controlled to adjust the rate of material discharge from the container 200. In the embodiment displayed with reference to Figs. 1-3, the drying system 100 comprises two feed screws 240 in a respective screw shaft 241, arranged essentially parallel to each other and arranged below a respective material outlet 220.

[0044] The air outlet (not shown) is located at the top of the container 200. The air outlet serves a function in the operation of the container 200 by allowing humid air to exit the container 200 after passing through the material in the container 200. The air outlet may help to maintain the pressure balance within the container 200 for efficient operation of the container 200. In some configurations, the air outlet may comprise a filter or a dust collection system to minimize the release of dust into the environment during the discharge of air from the container 200.

[0045] The agitator arrangement 300 displayed in Fig. 4 is designed to agitate the material in the container 200. The agitator arrangement 300 comprises a rotation axis 310 and agitation wings 320 that are used to agitate the material. The agitator arrangement 300 is arranged to agitate the material above the air distribution arrangement 400. As such, the agitation takes place above the air distribution arrangement 400.

[0046] With reference to Fig. 4, the rotation axis 310 is a component of the agitator arrangement 300 that is designed to transfer rotational movement to the agitation wings 320 of the agitator arrangement 300. In one embodiment, the rotation axis 310 extends from the top of the container 200 to near the air distribution arrangement 400. In an alternative embodiment, the rotation axis 310 extends through the air distribution arrangement 400. In one embodiment, the rotation axis 310 additionally extends through the floor 250 of the container 200. The rotation axis 310 is connected to a drive unit that provides the rotational movement. The rotation axis 310 is designed to withstand the forces generated during the agitation of the material and to ensure the smooth and efficient operation of the agitator arrangement 300.

[0047] The agitation wings 320 are components of the agitator arrangement 300 that are used to agitate the material in the container 200. The agitation wings 320 are arranged above the air distribution arrangement 400. The agitation wings 320 are preferably made of metal, which provides rigidity and strength. The agitation wings 320 are more preferably steel. The agitation wings 320 are connected to the rotation axis 310 and rotate with the rotation axis 310 to agitate the material. The agitation wings 320 each comprise a horizontal portion. The horizontal portion of the agitation wings 320 comprises a proximal end connected to the rotation axis 310, and a distal end extending towards the wall of the container 200. The agitation wings 320, and thus the horizontal portions, preferably extend essentially parallel to an upper surface of the air distribution arrangement 400. In one embodiment, the horizontal portion has a length that is near the length of the radius of the container 200. The horizontal portion is designed to agitate the material in the container 200 in a manner that facilitates the flow of material towards the material outlet 220. The agitation wings 320 are designed to ensure efficient agitation of the material and to minimize the formation of agglomerated material or moisture pockets in the material in the container 200. In one embodiment, the agitator arrangement 300 comprises only one agitation wing. In one embodiment, the agitator arrangement 300 comprises at least two agitation wings 320 to enhance the agitation of the material. The design and number of wings may be determined based on the material in the container 200.

[0048] With reference to Fig. 5a and Fig. 5b, the air distribution arrangement 400 is displayed. The air distribution arrangement 400 comprises a plate 410. The plate 410 guides the flow of dry air in the container 200 in a manner that promotes even distribution of dry air throughout the material. The plate 410 comprises an upper major surface 411, a bottom major surface 412, and a circumferential edge 413. The circumferential edge 413 defines the circumference of the plate 410, and the air distribution arrangement 400 guides the flow of dry air around the circumferential edge 413 into the material in the container 200. Because the air must pass around the circumferential edge 413, the flow of air through the material becomes close to laminar in an upwards direction through the container 200. The plate 410 is preferably made of a strong and durable material, such as metal, preferably steel, to ensure its longevity and reliability. In one embodiment, plate 410 has a thickness of 3-10 mm, preferably of 3-7 mm, more preferably 3-5 mm, most preferably 4 mm. Having a thin plate 410 provides that it can be easily removed for example during cleaning or repair.

[0049] The air distribution arrangement 400 is designed to distribute dry air in the container 200. When dry air enters through the dry air inlet 230 at the bottom of the container 200, the air is guided in the direction of the arrows displayed in Fig. 5b. Guiding the dry air around the edge of the plate 410 promotes a laminar flow of dry air through the material above the plate 410, the laminar flow being in an upwards, essentially vertical direction through the container 200.

[0050] In the displayed embodiments, the plate 410 comprises two halves, which is visualized by a lengthwise joint. The possibility to separate the plate 410 in two halves facilitates assembly of the plate 410 in the container 200, as the plate 410 can be installed and removed in sections. In alternative embodiments, the plate 410 is formed in one piece. In one embodiment, the plate 410 comprises a central hole through which the rotation axis 310 of the agitator arrangement 300 may extend. In such an embodiment it is especially beneficial to have the plate 410 provided in two halves, as installation of the plate 410 around the rotation axis 310 is facilitated.

[0051] In the embodiments displayed in the figures, the circumferential edge 413 comprises a slanting section 414. The slanting section 414 is angled downwards towards the bottom of the container 200. The slanting section 414 is preferably positioned vertically above the material outlet 220. The slanting section 414 provides that the material flowing towards the material outlet 220 is guided towards the material outlet 220. The slanting section 414 furthermore provides that the material is not caught on the circumferential edge 413 of the dry air distribution arrangement 400 or, as the case may be, forms piles of material on the circumferential edge 413. In one embodiment, the slanting section 414 constitutes a minority of the circumferential edge 413, such that dry air can easily flow around the remainder of the circumferential edge 413. In one embodiment, the slanting section 414 comprises one or several passageways for the dry air, for example perforations 421, or the circumferential edge 413 may comprise several shorter slanting sections 414 arranged at a distance from each other such that dry air may pass therebetween. In one embodiment, the circumferential edge 413 comprises at least two slanting sections 414. In one embodiment, the container 200 comprises two material outlets 220 to facilitate the efficient and controlled discharge of material from the container 200, in which embodiment the circumferential edge 413 comprises two slanting sections 414 to be arranged above the material outlets 220. In one example, the plate 410 has an oval shape, and two slanting sections 414 are arranged opposite each other on the two longer sides. In one example, the plate 410 has an oval shape, and two slanting sections 414 are arranged on points of the circumferential edge 413 corresponding to a minor axis. The slanting section 414 may be manufactured by bending or folding a section of the circumferential edge 413. Alternatively, the slanting section 414 may be manufactured in other manners such as by attaching an additional piece of metal plate 410 to the circumferential edge 413, for example by welding, wherein the additional piece of metal plate 410 is attached at a downwards angle in relation to the plate 410.

[0052] Fig. 6 displays the air distribution arrangement 400 from above. In the embodiment displayed in Fig. 6, the plate 410 has an oval shape. In the context of the present disclosure, an oval shape should not be strictly construed according to the mathematical definition of an ellipse, but also encompasses shapes for example having two essentially parallel sides connected by two semi-circles. As such, a major axis of the plate should be understood as the distance between the two most widely separated points of the circumferential edge 413, and when reference is made to a major semiaxis, this should be understood as half this distance. In one embodiment, the major semiaxis of the oval plate 410 is essentially equal to half of a radius of the container 200. The oval shape contributes to the even distribution of dry air, as the dry air comes into contact with the material in the container 200 at different positions in relation to a radius of the container 200.

[0053] In the alternative embodiment displayed in Fig. 7, the plate 410 has a circular shape. In one embodiment, the radius of the circular plate 410 is essentially equal to half of a radius of the container 200.

[0054] Turning now to Fig. 8, the air distribution arrangement 400 is positioned above the dry air inlet 230, the plate 410 having an essentially horizontal extension in the container 200. The air distribution arrangement 400 is preferably positioned close to the floor 250 of the container 200. In one embodiment, the air distribution arrangement 400 rests on the floor 250 of the container 200. In one embodiment, the air distribution arrangement 400 comprises means for arranging the air distribution arrangement 400 at a predetermined distance above the floor 250, such as legs.

[0055] The air distribution arrangement 400 preferably comprises a distribution means 420 designed to additionally enhance the even distribution of dry air in the container 200. The distribution means 420 is arranged below the plate 410 of the dry air distribution arrangement 400. In one embodiment, the distribution means 420 is arranged between the floor 250 and the plate 410 in a way such that air from the dry air inlet 230 only can escape through the distribution means 420. To this end, the distribution means 420 comprises openings or perforations or mesh-like material for the dry air to escape through. The air distribution means 420 is preferably made of a strong and durable material, such as metal, to ensure its longevity and reliability.

[0056] In the embodiment displayed with reference to Fig. 9, the distribution means 420 comprises a perforated flange extending from the bottom major surface 412 of the plate 410. The perforated flange is positioned on the bottom major surface 412 at a predetermined distance from the circumferential edge 413. The perforated flange preferably forms a closed loop on the bottom major surface 412. The perforated flange preferably has a shape which mirrors the circumference of the plate 410. In one embodiment, the air distribution arrangement 400 rests on the floor 250 of the container 200, specifically on the distribution means 420. In one embodiment, the air distribution arrangement 400 rests on the perforated flange and the dry air inlet 230 is arranged within the closed loop of the perforated flange, such that dry air is guided through the perforated flange. In other words, the closed loop is arranged to surround the dry air inlet 230.

[0057] The perforated flange comprises perforations 421 through which dry air from the dry air inlet 230 flows. The perforations 421 are preferably arranged side by side at even distances from each other along the flange. The perforations 421 may for example be round, slit-shaped, or keyhole-shaped.

[0058] With reference to Fig. 10, there is displayed a material handling system, of which the present drying system 100 forms a part. The material handling system transports material from the drying system 100 to a subsequent processing step, such as a further drying step. The material handling system is preferably arranged in connection to a compounding extruder, for example for compounding of bio-composites. The material handling system may comprise a plurality of the drying system 100, for example for different materials to be mixed in subsequent processing steps.

[0059] Preferred embodiments of a drying system have been disclosed above. However, a person skilled in the art realizes that this can be varied within the scope of the appended claims without departing from the inventive idea.

[0060] All the described alternative embodiments above or parts of an embodiment can be freely combined or employed separately from each other without departing from the inventive idea as long as the combination is not contradictory.

Examples

Embodiment Construction

[0035]In the following, a detailed description of a system for drying a material, and a method for drying a material, is described. In the figures, like reference numerals designate identical or corresponding elements throughout the figures. It will be appreciated that these figures are for illustration only and do not in any way restrict the scope of the present disclosure.

[0036]With reference to Fig. 1 and Fig. 2 there is displayed a drying system 100 according to the disclosure. The drying system 100 generally comprises a container 200, an agitator arrangement 300 and an air distribution arrangement 400. The drying system 100 is preferably part of a material handling system, such as for handling material components for composite materials, such as bio-composites. An example of such a material handling system is described below with reference to Fig. 10.

[0037]The container 200 is the primary structure of the drying system 100. It is designed to contain and handle material in a con...

Claims

1. A drying system (100) for drying a material, the drying system (100) comprising: a container (200) for feeding material from a material inlet (210) at a top of the container (200) to a material outlet (220) at a bottom of the container (200), a dry air inlet (230) at the bottom of the container (200), an air distribution arrangement (400) comprising a plate (410) arranged above the dry air inlet (230), and an agitator arrangement (300), for agitating the material in the container (200), wherein the agitation takes place above the plate (410), wherein dry air is arranged to flow from the dry air inlet (230) and around an edge of the plate (410), to dry the material in the container (200).

2. Drying system (100) according to claim 1, wherein the air distribution arrangement (400) further comprises a distribution means (420) extending from a bottom major surface of the plate (410), through which the dry air is guided before passing around the edge of the plate (410).

3. Drying system (100) according to claim 2, wherein the distribution means (420) comprises a perforated flange extending from the bottom major surface of the plate (410), the perforated flange forming a closed loop on the bottom major surface.

4. Drying system (100) according to claim 3, wherein air distribution arrangement (400) is carried by the perforated flange which rests on the bottom of the container (200).

5. Drying system (100) according to any one of the preceding claims, wherein the plate (410) is arranged essentially horizontally in the container (200).

6. Drying system (100) according to any one of the preceding claims, wherein the plate (410) has an essentially oval shape, the major semiaxis of which is essentially equal to half of a radius of the container (200).

7. Drying system (100) according to any one of the preceding claims, wherein at least a section (414) of an edge of the plate (410) is slanting towards the bottom of the container (200).

8. Drying system (100) according to claim 7, wherein the material outlet (220) of the container (200) is arranged below the slanting section (414) of the edge.

9. Drying system (100) according to any one of the preceding claims, wherein the agitator arrangement (300) comprises: a rotation shaft (310) extending vertically from the top of the container (200) towards the plate (410), and at least one agitation wing (320) extending essentially horizontally from the rotation shaft (310), wherein the at least one agitation wing (320) is arranged to rotate above the plate (410).

10. A method for drying a material in a drying system (100), the method comprising: providing a continuous feeding of material from a material inlet (210) at a top of the drying system (100) to a material outlet (220) at a bottom of the drying system (100), and providing a flow of dry air from the bottom of the drying system (100), wherein the flow of dry air, after entering the drying system (100), passes an air distribution arrangement (400) before reaching the material to be dried, the air distribution arrangement (400) comprising a plate (410) around the edge of which the dry air is arranged to flow.

11. Method according to claim 10, wherein the material is an organic material, such as an organic fiber material.

12. Method according to claim 10 or 11, further comprising agitating the material in the drying system (100), the agitation taking place at a position above the air distribution arrangement (400).

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