Drying and feeding arrangement

Abstract

An arrangement (100) for feeding and drying a material, the arrangement (100) comprising a shaft (110) for transport of the material, a feed screw (120) arranged in the shaft (110) for feeding the material through the shaft (110), a heating means (130) provided outside the shaft (110) and arranged to heat the arrangement (100) to dry the material in the shaft (110).

Description

Technical field

[0001] The present invention relates generally to arrangements, systems and methods for material transport, for drying of materials, and for production of bio-composites.Background art

[0002] Compound extrusion is the common approach to mixing polymers and additives within the plastic industry. A compounding extruder has the purpose of mixing two or more material components together to form a composite material, by means of one or more compounding screws in the compounding extruder.

[0003] 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 come from a natural source such as forestry or an agricultural source, and examples include materials such as hemp or cellulose. The 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.

[0004] The field of handling organic materials and organic particles is unexplored and there is a need for innovative solutions in many areas.

[0005] Many challenges with the organic particles are associated with their low bulk density, which is the density of a volume of many particles (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.

[0006] Feeding low bulk density materials is not trivial. Since the particles in low bulk density materials are light and surrounded by air, they form a volume which does not for example 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. This can cause the material to form a lid, or wall, and block the passage of further material.

[0007] Drying low bulk density materials is difficult, many times due to the same material properties that cause problems with feeding the material. The light weight, and surrounding air makes removal of moisture difficult as there is a risk of formation of moisture pockets where the water collects which are hard to remove. A prerequisite for feeding organic particles into the compounding extruder is that it has low or zero retained water. 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 system which may be considered often comprise a drying chamber in which the material is contained during drying. The material is removed from the chamber after it has been dried. Such systems are not sufficiently space efficient or energy efficient.

[0008] As such there is need for improved solutions for feeding and drying low bulk density materials, such as organic materials.Summary of invention

[0009] An object of the present invention is to overcome at least some of the problems outlined above.

[0010] In a first aspect of the disclosure there is provided an arrangement for feeding and drying a material. The arrangement comprises a shaft for transport of the material, a feed screw arranged in the shaft for feeding the material through the shaft, a heating means provided outside the shaft and arranged to heat the arrangement to dry the material in the shaft.

[0011] The present invention provides that the moisture level of a material can be reduced at the same time as it is transported. This increases efficiency, as the need for removing moisture in subsequent processing steps is reduced. Today, moisture is commonly removed in a separate system, before being fed into for example a compounding extruder, and / or the compounding extruder may comprise degassing sections to ensure the water is removed from the compound. By means of the present solution, the need for these steps is reduced or even completely removed. An advantage of this is that the compounding process may be directed more expressly on the homogenization of the material and thus a material of higher quality can be achieved.

[0012] The drying of the material is provided by heating the material which is being transported by the arrangement. The heating is provided by the heating means. The material in the shaft may be heated by being in contact with a heated inner surface of the shaft, and / or a heated outer surface of the feed screw. In a preferred embodiment, the arrangement brings the material to a temperature ≥ 100° C, that is, to a temperature ≥ the boiling point of water such that residual water in the material is evaporated. Since the material is heated by being in contact with the heated arrangement, the material can reach higher temperatures, compared to for example providing a flow of hot air to heat / dry the material. Specifically, the material can reach higher temperatures without the air surrounding the material having to reach equally high temperatures. In other words, the arrangement provides that the material can have a higher temperature than the air which surrounds it.

[0013] Furthermore, since the material is transported by a feed screw which rotates and thus mixes / agitates the material during feeding, the drying becomes more efficient as more material comes into contact with the heated arrangement. The movement of the material during drying furthermore reduces the risk of forming local moisture pockets and ensures that the heat is evenly distributed.

[0014] In a preferred embodiment, the material is one of an organic material, a fiber material, a naturally sourced material such as, but not limited to, sourced from agriculture or forestry, or combination thereof.

[0015] In an exemplary embodiment, the shaft comprises at least two layers of different materials, wherein at least one layer is chosen from a metal layer, a ceramic layer and a polymer layer. In an exemplary embodiment, the shaft comprises a metal layer as an outermost layer, and a ceramic layer adjacent the metal layer.

[0016] The construction of the shaft can provide different properties to the arrangement. Metal can be provided to improve rigidity and thermal properties, such as good heat transfer. Ceramic can be provided to increase wear resistance, and thermal properties such as good heat transfer. Both metal and ceramic furthermore have the advantage of maintaining its beneficial properties at increased temperatures, for example at temperatures ≥ 100° C. Polymer can be provided to decrease friction, for example between the shaft and the feed screw such that the feed screw moves smoothly in the shaft. Decreased friction also decreases the risk of spark formation, which provides a safer arrangement with decreased risk of explosions.

[0017] In an exemplary embodiment, the heating means is arranged in contact with an outside surface of the shaft.

[0018] When the heating means is in contact with the shaft, the heating means can transfer heat directly to the shaft and heat the shaft. as such, the material inside the shaft is heated through heat transfer via the shaft.

[0019] In an exemplary embodiment, the feed screw is arranged in contact with an inside surface of the shaft. In an exemplary embodiment, the feed screw rests at the bottom of the shaft.

[0020] When the feed screw is in contact with the shaft, it is possible to achieve thermal conduction between the shaft and the feed screw. As such, the feed screw can be heated efficiently by the heating means, via the shaft. Furthermore, if the feed screw rests at the bottom of the shaft, there is no bending moment acting on the feed screw and thus provides a more durable solution. Furthermore, the construction is simpler as there is no need to provide means for suspending the feed screw in the shaft.

[0021] In an exemplary embodiment, the heating means is arranged to heat the shaft and / or the feed screw by thermal conduction.

[0022] In an exemplary embodiment, the heating means comprises heat cords heated through resistive heating.

[0023] In an exemplary embodiment, the arrangement further comprises a dry air inlet through which dry air is arranged to flow into the shaft and in a direction being opposite of a feeding direction of the material through the shaft.

[0024] The water which is evaporated from the material is preferably removed by a flow of dry air through the shaft. After passing the shaft, the humid air can be let out from the shaft, at an end opposite where the dry air inlet is arranged. An air flow for removal of moisture is advantageous because the air can efficiently reach the entire volume of the material and prevents the formation of moisture pockets. The flow of air can also be utilized to control a temperature inside the shaft, such that the air within the shaft remains at a safe temperature. To high air temperatures increases fire hazard and risk of explosions.

[0025] In an exemplary embodiment, the arrangement further comprises an air flow generator. The air flow generator is arranged to provide a flow of dry air into a dry air inlet of the arrangement. The air flow generator is furthermore arranged to provide a flow of dry air in a direction opposite of a feeding direction of the material through the shaft. The air flow generator may furthermore comprise an air drier for removing moisture, such that the air which flows into the dry air inlet has a moisture level of essentially 0%. The air flow generate may furthermore comprise a temperature controller, to control the temperature of the dry air entering the dry air inlet.

[0026] In an exemplary embodiment, the dry air has a temperature when entering the dry air inlet being ≤ 60°C, preferably 10-50°C, more preferably 20-40°C, even more preferably 30-35°C.

[0027] According to a second aspect of the disclosure, there is provided a method for feeding and drying a material, the method comprising: feeding a material through a shaft by means of a feed screw, heating the shaft and the feed screw by means of a heating means arranged outside the shaft, wherein the material is dried by being heated by the shaft and feed screw.

[0028] In an exemplary embodiment, the heating means heats the feed screw through thermal conduction via the shaft.

[0029] In an exemplary embodiment, the material is heated by thermal conduction from the shaft and feed screw.

[0030] In an exemplary embodiment, the method further comprises directing an air flow through the shaft in a direction being opposite of a feeding direction of the material, wherein a moisture level of the air is essentially 0% when entering the shaft.

[0031] In an exemplary embodiment, the material has a temperature ≥ 100°C inside the shaft.Brief description of drawings

[0032] The invention is now described, by way of example, with reference to the accompanying drawings, in which: Figs. 1a-1b display an embodiment of an arrangement according to the disclosure. Figs. 2a-2b display an embodiment of an arrangement according to the disclosure. Figs 3a-3b display a cross-section of a shaft according to the disclosure. Fig. 4 displays an embodiment of an arrangement according to the disclosure having material therein. Fig. 5 displays a material handling system according to the disclosure. Description of embodiments

[0033] In the following, a detailed description of the different embodiments of the invention will be disclosed under reference to the accompanying drawings. All examples herein should be seen as part of the general description and are therefore possible to combine in any way in general terms. Individual features of the various embodiments may be combined or exchanged unless such combination or exchange is clearly contradictory to the overall function of the system.

[0034] In Figs. 1a, 1b, 2a and 2b, there is displayed an arrangement 100 according to the present disclosure. The arrangement 100 generally comprises a shaft 110, a feed screw 120 arranged in the shaft 110, and a heating means 130 arranged outside the shaft 110.

[0035] The arrangement 100 according to the present disclosure is arranged to both transport material, and simultaneously dry the material as it is transported. The arrangement 100 is preferably part of a material handling system, such as for material components for composite materials, such as bio-composites. An example of such a system is displayed with reference to Fig. 5.

[0036] Embodiments of the shaft 110 are described below.

[0037] The material to be dried is transported through the shaft 110. To this end, the shaft 110 generally comprises at least one material inlet 111 and at least one material outlet 112.

[0038] In one embodiment, the shaft 110 comprises more than one material inlet 111. As such, the arrangement 100 can receive and dry more than one material at a time, and furthermore mix said materials in the shaft 110 during transport and drying thereof. In embodiments having more than one material inlet embodiment, the arrangement 100 preferably comprises only one material outlet 112, such that the mixed materials exit the arrangement 100 together.

[0039] The shaft 110 is arranged to be heated by the heating means 130 and may thereby dry the material which is fed through the shaft 110.

[0040] A cross-section of embodiments of the shaft 110 is displayed with reference to Figs. 3a and 3b. The shaft 110 comprises at least a first layer 113 of material. A layer is herein understood as corresponding to at least a part of the mantle surface of the shaft 110. In one embodiment, the shaft 110 comprises more than one layer of material. The embodiment displayed in Fig. 3a additionally comprises a second layer 114 and the embodiment displayed in Fig. 3b additionally comprises a third layer 115.

[0041] In one embodiment, the shaft 110 comprises a metal layer. The metal layer may for example be a steel layer, or an aluminum layer. Preferably, the metal layer is a corrosive resistant metal. Preferably, the metal layer is made of a metal having an average or above average thermal conductivity. In one embodiment, the shaft 110 comprises the metal layer as an outermost layer, that is, corresponding to an outer surface of the shaft 110. The metal layer improves the heat transfer from the heating means 130, such that heat losses are decreased. Furthermore, the metal layer provides rigidity to the shaft 110. In one embodiment the metal layer has a thickness of 2-6 mm, preferably 3-5 mm. The thickness is an important parameter which determines the rigidity of the shaft 110. The shaft 110 needs to be sufficiently rigid to maintain its own weight without bending. The thickness furthermore determines the resistance to dents. A dented surface may decrease the heat transfer from the heating means 130 to the shaft 110.

[0042] In one embodiment, the shaft 110 comprises a polymer layer. The polymer layer may for example be a fluoroplastic layer, such as a PTFE layer, or a polymer known under the trade name TEFLON. In one embodiment, the shaft 110 comprises the polymer layer as an innermost layer. The polymer layer decreases friction between the shaft 110 and the feed screw 120 such that the feed screw 120 moves smoothly in the shaft 110. Decreased friction also decreases the risk of spark formation, which provides a safer arrangement 100 with decreased risk of explosions. In one embodiment, the polymer layer has a thickness ≤ 20 micrometers, preferably < 20 micrometers.

[0043] In one embodiment, the shaft 110 comprises a bearing layer. The bearing layer may for example be a ceramic layer, for example an aluminum oxide layer. The bearing layer transfers heat from the heating means 130 to the material inside the shaft 110. The bearing layer is preferably arranged within the metal layer, wherein the bearing layer transfers heat from the metal layer to the material inside the shaft 110. In one embodiment, the shaft 110 comprises the bearing layer as an innermost layer. In an alternative embodiment, the shaft 110 comprises the bearing layer as an intermediate layer, for example arranged between the metal layer and the polymer layer. The bearing layer provides wear resistance to the shaft 110. In some embodiments, the feed screw 120 is arranged in contact with the shaft 110 and thus rotates against and in contact with the shaft 110. As such, the shaft 110 needs to be resistance to wear. Specifically, the shaft 110 needs to have an inner layer with a hardness above that of the feed screw 120, to increase wear resistance. For example, in a case where the feed screw 120 is made of a metal, such as steel, the shaft 110 is provided with a layer having a higher hardness than steel, such as aluminum oxide. In one embodiment, the bearing layer has a thickness of 20-1000 micrometer, preferably 100-500 micrometer, more preferably 300 micrometers.

[0044] The term shaft 110 should not be understood as limiting to the scope of the disclosure. The shaft 110 may also be referred to as a duct or a conduit or a pipe. Furthermore, the shaft 110 may have any cross-sectional shape, such as circular or rectangular, or combinations thereof, such as a circular bottom half and another geometry for the upper half.

[0045] Embodiments of the heating means 130 are described below.

[0046] The heating means 130 is provided outside the shaft 110, and is arranged to heat the arrangement 100. Specifically, the heating means 130 is arranged to, directly or indirectly, heat the shaft 110 and the feed screw 120. The heating means 130 has the effect that the material inside the shaft 110 is heated and thus residual water in the material is evaporated and thus the material is dried.

[0047] In one embodiment, the heating means 130 comprises heat cords, such as metal cords heated by electrical resistance. The heat cords are preferably arranged in direct contact with an outer layer of the shaft 110. With reference to Figs. 1a and 1b, the heat cords are arranged along a lengthwise extension of the shaft 110, and arranged in a wavy pattern. Alternatively, as displayed in Figs. 2a and 2b, the heat cords are wound around the shaft 110. The heat cords are arranged to evenly distribute heat over the mantle surface of the shaft 110. As such, the patterns displayed in Figs. 1a, 1b, 2a and 2b are not limiting to the scope of the disclosure.

[0048] In an alternative embodiment, the heating means 130 comprises a heating mantle. A heating mantle provides a heated liquid which encloses the shaft 110, or part of the shaft 110, for heating thereof. The heated liquid may for example be oil or a gas. Heating mantles are known to the skilled person. For example, it may be advantageous to utilize excess heat from another process a heating mantle where there is access to which can be used to heat the liquid.

[0049] In an alternative embodiment, the heating means 130 is an induction heating means 130, arranged to inductively heat the arrangement 100. In one embodiment, the feed screw 120 is heated by the induction heating means 130. In one embodiment, the shaft 110 is heated by the induction heating means 130, and the screw is heated by the shaft 110 through conduction.

[0050] In one embodiment, the arrangement 100 comprises an insulation outside the heating means 130. The insulation provides that the arrangement 100 is safer and more energy efficient.

[0051] Embodiments of the feed screw 120 are described below.

[0052] The feed screw 120 is arranged to be heated by the heating means 130 and may thereby dry the material which it is feeding through the shaft 110. The material to be dried is transported through the shaft 110 by means of the feed screw 120. The feed screw 120 is arranged to rotate inside the shaft 110. To this end, the arrangement 100 further comprises an electrical rotation unit (not shown), connected to the feed screw 120 and arranged to provide rotation of the feed screw 120. In one embodiment, the feed screw 120 rests on the bottom of the shaft 110.

[0053] In one embodiment the feed screw 120 is made by metal. The properties of the metal need to both enable the feed screw 120 to be rigid along its entire length, as well as having a sufficient heat conductivity. Preferably, the feed screw 120 is made by steel. In one embodiment, the feed screw 120 is a shaftless feed screw 120. A shaftless feed screw 120 is suitable for transport of low bulk density materials.

[0054] The arrangement 100 preferably also comprises means for removal of water leaving the material during drying. This prevents water condensing back onto the material.

[0055] As the feed screw 120 transports the material forward through the shaft 110, the material tends to fill the bottom half of the shaft 110 due to gravity, while the upper half remains empty. As the material is heated and residual water in the material is vaporized, the hot steam accumulates in the upper half of the shaft 110. The water should thus preferably be removed, to prevent the water from condensing back onto the material.

[0056] In one embodiment the water is removed by directing an air flow through the shaft 110, flowing in a direction opposite the feeding direction of the material in the shaft 110. To this end, dry air enters the shaft 110 through a dry air inlet 116 (seen in Fig. 4) near a material outlet 112 of the shaft 110. The dry air, when entering the shaft 110, preferably has a moisture level of essentially 0%. When the air exits the arrangement 100, the air has a moisture level > 0%. The air flow provides an efficient removal of moisture. Furthermore, since the material has a low bulk density, the air not only flows through any open space in the shaft, such as the upper half of the shaft 110, but flows through the material and provides removal of moisture throughout the entire volume of the material. This decreases the risk of local moisture pockets.

[0057] Fig. 4 displays a material handling system 200. The material handling system 200 may for example be arranged to transport a material to a compounding extruder, in which bio-composites are produced. The material handling system 200 may for example transport an organic material, such as an organic fiber, to be compounded together with a polymer in a compounding extruder to produce bio-composites.

[0058] The material handling system 200 in Fig. 4 comprises the arrangement 100, a first and a second auxiliary shaft 210, 211. The first and second auxiliary shaft 210, 211 each feeds material into the arrangement 100, through a first and second material inlet in the shaft thereof. The first and second auxiliary shaft 210, 211 are preferably for feeding different material into the arrangement 100. Alternatively, the material handling system 200 may comprise one or several auxiliary shafts for feeding material into the arrangement 100. Alternatively, the material may be inserted into the arrangement 100 in a different way than through an auxiliary shaft, such as manually inserted through a material inlet of the shaft.

[0059] The material may be an organic particle from a natural source such as forestry or an agricultural source. The organic particle may be an organic fiber, such as a reinforcing organic fiber. The organic fiber may be, but is not limited to, agriculturally sourced fiber, hemp fiber, cellulose fiber, or combinations thereof.

[0060] A method according to the present disclosure thus comprises feeding at least one material into the arrangement 100. The material when entering the shaft can for example have a moisture level > 5%, or > 10%, or > 20%.

[0061] The method furthermore comprises drying the material inside the shaft, during feeding of the material through the shaft.

[0062] The material is dried by heat provided from the arrangement 100, in that the arrangement 100 is heated and the heat is transferred to the material therein. In one embodiment, drying comprises reducing the moisture level in the material such that the moisture level is essentially 0% when exiting the arrangement 100. In this embodiment, the arrangement 100 is preferably provided as a last drying step in the material handling system 200, before the material moves to the next processing step such as a compounder. In an alternative embodiment, drying comprises reducing the moisture level in the material such that it is has a predetermined moisture level when exiting the arrangement 100. In this embodiment, the arrangement 100 is preferably provided as an intermediate drying step in the material handling system 200.

[0063] In one embodiment, the method comprises transferring heat to the material by thermal conduction from the arrangement 100. This is preferably achieved by the material being in direct contact with the inside surface of the heated shaft and / or the heated feed screw. There are several advantages with heating the material in this manner. One advantage is that the thermal conduction between two solid materials, such as metal and organic fiber, is more efficient than thermal conduction between a solid and a gas, such as air and organic fiber. Another advantage is that the material may reach a temperature which is higher than the surrounding air in the shaft. In some material handling systems, there is a maximum temperature of the air surrounding the material, for example for safety reasons to prevent spark formation and explosions. As such, by heating the material by thermal conduction from the (solid) arrangement 100, instead of heating through a heated gas such as warm air, the material can safely reach a temperature above the maximum allowed air temperature. In one embodiment, the material has a temperature ≥ 100°C when it is inside the arrangement 100. In one embodiment, the air inside the arrangement 100 has a temperature below 100°C, preferably below 70°C, more preferably below 60°C even more preferably 10-50°C, even more preferably 20-40°C, most preferably 30-35°C. In one embodiment, the dry air has a temperature when entering the dry air inlet being below 100°C, preferably below 70°C, more preferably below 60°C even more preferably 10-50°C, even more preferably 20-40°C, most preferably 30-35°C. In one embodiment, the dry air has a temperature when exiting the arrangement 100 being below 100°C, preferably below 70°C, more preferably below 60°C.

[0064] Feeding the material may comprise continuously feeding material. Feeding material may also comprise sequential feeding, that is, a combination of feeding and pausing, to ensure the material is sufficiently dry when exiting the arrangement 100. Feeding the material may comprise feeding at different feeding rates or a constant feeding rate.

[0065] In one embodiment, the method comprises directing an air flow through the shaft in a direction being opposite of a feeding direction of the material.

[0066] In an exemplary embodiment, the material handling system 200 further comprises an air flow generator 212. The air flow generator 212 is arranged to provide a flow of dry air into the dry air inlet 116 of the arrangement. The air flow generator 212 is furthermore arranged to provide a flow of dry air in a direction opposite of a feeding direction of the material through the shaft. The air flow generator 212 may furthermore comprise an air dryer for removing moisture, such that the air which flows through the dry air inlet has a moisture level of essentially 0%.

[0067] In all embodiments according to the present disclosure, when reference is made to a metal, this should be understood as either a pure metal or a metal alloy.

[0068] Preferred embodiments of an arrangement, a system and a method 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.

[0069] 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

[0033]In the following, a detailed description of the different embodiments of the invention will be disclosed under reference to the accompanying drawings. All examples herein should be seen as part of the general description and are therefore possible to combine in any way in general terms. Individual features of the various embodiments may be combined or exchanged unless such combination or exchange is clearly contradictory to the overall function of the system.

[0034]In Figs. 1a, 1b, 2a and 2b, there is displayed an arrangement 100 according to the present disclosure. The arrangement 100 generally comprises a shaft 110, a feed screw 120 arranged in the shaft 110, and a heating means 130 arranged outside the shaft 110.

[0035]The arrangement 100 according to the present disclosure is arranged to both transport material, and simultaneously dry the material as it is transported. The arrangement 100 is preferably part of a material handling system, such as for material components for c...

Technical field

[0001] The present invention relates generally to arrangements, systems and methods for material transport, for drying of materials, and for production of bio-composites.Background art

[0002] Compound extrusion is the common approach to mixing polymers and additives within the plastic industry. A compounding extruder has the purpose of mixing two or more material components together to form a composite material, by means of one or more compounding screws in the compounding extruder.

[0003] 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 come from a natural source such as forestry or an agricultural source, and examples include materials such as hemp or cellulose. The 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.

[0004] The field of handling organic materials and organic particles is unexplored and there is a need for innovative solutions in many areas.

[0005] Many challenges with the organic particles are associated with their low bulk density, which is the density of a volume of many particles (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.

[0006] Feeding low bulk density materials is not trivial. Since the particles in low bulk density materials are light and surrounded by air, they form a volume which does not for example 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. This can cause the material to form a lid, or wall, and block the passage of further material.

[0007] Drying low bulk density materials is difficult, many times due to the same material properties that cause problems with feeding the material. The light weight, and surrounding air makes removal of moisture difficult as there is a risk of formation of moisture pockets where the water collects which are hard to remove. A prerequisite for feeding organic particles into the compounding extruder is that it has low or zero retained water. 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 system which may be considered often comprise a drying chamber in which the material is contained during drying. The material is removed from the chamber after it has been dried. Such systems are not sufficiently space efficient or energy efficient.

[0008] As such there is need for improved solutions for feeding and drying low bulk density materials, such as organic materials.Summary of invention

[0009] An object of the present invention is to overcome at least some of the problems outlined above.

[0010] In a first aspect of the disclosure there is provided an arrangement for feeding and drying a material. The arrangement comprises a shaft for transport of the material, a feed screw arranged in the shaft for feeding the material through the shaft, a heating means provided outside the shaft and arranged to heat the arrangement to dry the material in the shaft.

[0011] The present invention provides that the moisture level of a material can be reduced at the same time as it is transported. This increases efficiency, as the need for removing moisture in subsequent processing steps is reduced. Today, moisture is commonly removed in a separate system, before being fed into for example a compounding extruder, and / or the compounding extruder may comprise degassing sections to ensure the water is removed from the compound. By means of the present solution, the need for these steps is reduced or even completely removed. An advantage of this is that the compounding process may be directed more expressly on the homogenization of the material and thus a material of higher quality can be achieved.

[0012] The drying of the material is provided by heating the material which is being transported by the arrangement. The heating is provided by the heating means. The material in the shaft may be heated by being in contact with a heated inner surface of the shaft, and / or a heated outer surface of the feed screw. In a preferred embodiment, the arrangement brings the material to a temperature ≥ 100° C, that is, to a temperature ≥ the boiling point of water such that residual water in the material is evaporated. Since the material is heated by being in contact with the heated arrangement, the material can reach higher temperatures, compared to for example providing a flow of hot air to heat / dry the material. Specifically, the material can reach higher temperatures without the air surrounding the material having to reach equally high temperatures. In other words, the arrangement provides that the material can have a higher temperature than the air which surrounds it.

[0013] Furthermore, since the material is transported by a feed screw which rotates and thus mixes / agitates the material during feeding, the drying becomes more efficient as more material comes into contact with the heated arrangement. The movement of the material during drying furthermore reduces the risk of forming local moisture pockets and ensures that the heat is evenly distributed.

[0014] In a preferred embodiment, the material is one of an organic material, a fiber material, a naturally sourced material such as, but not limited to, sourced from agriculture or forestry, or combination thereof.

[0015] In an exemplary embodiment, the shaft comprises at least two layers of different materials, wherein at least one layer is chosen from a metal layer, a ceramic layer and a polymer layer. In an exemplary embodiment, the shaft comprises a metal layer as an outermost layer, and a ceramic layer adjacent the metal layer.

[0016] The construction of the shaft can provide different properties to the arrangement. Metal can be provided to improve rigidity and thermal properties, such as good heat transfer. Ceramic can be provided to increase wear resistance, and thermal properties such as good heat transfer. Both metal and ceramic furthermore have the advantage of maintaining its beneficial properties at increased temperatures, for example at temperatures ≥ 100° C. Polymer can be provided to decrease friction, for example between the shaft and the feed screw such that the feed screw moves smoothly in the shaft. Decreased friction also decreases the risk of spark formation, which provides a safer arrangement with decreased risk of explosions.

[0017] In an exemplary embodiment, the heating means is arranged in contact with an outside surface of the shaft.

[0018] When the heating means is in contact with the shaft, the heating means can transfer heat directly to the shaft and heat the shaft. as such, the material inside the shaft is heated through heat transfer via the shaft.

[0019] In an exemplary embodiment, the feed screw is arranged in contact with an inside surface of the shaft. In an exemplary embodiment, the feed screw rests at the bottom of the shaft.

[0020] When the feed screw is in contact with the shaft, it is possible to achieve thermal conduction between the shaft and the feed screw. As such, the feed screw can be heated efficiently by the heating means, via the shaft. Furthermore, if the feed screw rests at the bottom of the shaft, there is no bending moment acting on the feed screw and thus provides a more durable solution. Furthermore, the construction is simpler as there is no need to provide means for suspending the feed screw in the shaft.

[0021] In an exemplary embodiment, the heating means is arranged to heat the shaft and / or the feed screw by thermal conduction.

[0022] In an exemplary embodiment, the heating means comprises heat cords heated through resistive heating.

[0023] In an exemplary embodiment, the arrangement further comprises a dry air inlet through which dry air is arranged to flow into the shaft and in a direction being opposite of a feeding direction of the material through the shaft.

[0024] The water which is evaporated from the material is preferably removed by a flow of dry air through the shaft. After passing the shaft, the humid air can be let out from the shaft, at an end opposite where the dry air inlet is arranged. An air flow for removal of moisture is advantageous because the air can efficiently reach the entire volume of the material and prevents the formation of moisture pockets. The flow of air can also be utilized to control a temperature inside the shaft, such that the air within the shaft remains at a safe temperature. To high air temperatures increases fire hazard and risk of explosions.

[0025] In an exemplary embodiment, the arrangement further comprises an air flow generator. The air flow generator is arranged to provide a flow of dry air into a dry air inlet of the arrangement. The air flow generator is furthermore arranged to provide a flow of dry air in a direction opposite of a feeding direction of the material through the shaft. The air flow generator may furthermore comprise an air drier for removing moisture, such that the air which flows into the dry air inlet has a moisture level of essentially 0%. The air flow generate may furthermore comprise a temperature controller, to control the temperature of the dry air entering the dry air inlet.

[0026] In an exemplary embodiment, the dry air has a temperature when entering the dry air inlet being ≤ 60°C, preferably 10-50°C, more preferably 20-40°C, even more preferably 30-35°C.

[0027] According to a second aspect of the disclosure, there is provided a method for feeding and drying a material, the method comprising: feeding a material through a shaft by means of a feed screw, heating the shaft and the feed screw by means of a heating means arranged outside the shaft, wherein the material is dried by being heated by the shaft and feed screw.

[0028] In an exemplary embodiment, the heating means heats the feed screw through thermal conduction via the shaft.

[0029] In an exemplary embodiment, the material is heated by thermal conduction from the shaft and feed screw.

[0030] In an exemplary embodiment, the method further comprises directing an air flow through the shaft in a direction being opposite of a feeding direction of the material, wherein a moisture level of the air is essentially 0% when entering the shaft.

[0031] In an exemplary embodiment, the material has a temperature ≥ 100°C inside the shaft.Brief description of drawings

[0032] The invention is now described, by way of example, with reference to the accompanying drawings, in which: Figs. 1a-1b display an embodiment of an arrangement according to the disclosure. Figs. 2a-2b display an embodiment of an arrangement according to the disclosure. Figs 3a-3b display a cross-section of a shaft according to the disclosure. Fig. 4 displays an embodiment of an arrangement according to the disclosure having material therein. Fig. 5 displays a material handling system according to the disclosure. Description of embodiments

[0033] In the following, a detailed description of the different embodiments of the invention will be disclosed under reference to the accompanying drawings. All examples herein should be seen as part of the general description and are therefore possible to combine in any way in general terms. Individual features of the various embodiments may be combined or exchanged unless such combination or exchange is clearly contradictory to the overall function of the system.

[0034] In Figs. 1a, 1b, 2a and 2b, there is displayed an arrangement 100 according to the present disclosure. The arrangement 100 generally comprises a shaft 110, a feed screw 120 arranged in the shaft 110, and a heating means 130 arranged outside the shaft 110.

[0035] The arrangement 100 according to the present disclosure is arranged to both transport material, and simultaneously dry the material as it is transported. The arrangement 100 is preferably part of a material handling system, such as for material components for composite materials, such as bio-composites. An example of such a system is displayed with reference to Fig. 5.

[0036] Embodiments of the shaft 110 are described below.

[0037] The material to be dried is transported through the shaft 110. To this end, the shaft 110 generally comprises at least one material inlet 111 and at least one material outlet 112.

[0038] In one embodiment, the shaft 110 comprises more than one material inlet 111. As such, the arrangement 100 can receive and dry more than one material at a time, and furthermore mix said materials in the shaft 110 during transport and drying thereof. In embodiments having more than one material inlet embodiment, the arrangement 100 preferably comprises only one material outlet 112, such that the mixed materials exit the arrangement 100 together.

[0039] The shaft 110 is arranged to be heated by the heating means 130 and may thereby dry the material which is fed through the shaft 110.

[0040] A cross-section of embodiments of the shaft 110 is displayed with reference to Figs. 3a and 3b. The shaft 110 comprises at least a first layer 113 of material. A layer is herein understood as corresponding to at least a part of the mantle surface of the shaft 110. In one embodiment, the shaft 110 comprises more than one layer of material. The embodiment displayed in Fig. 3a additionally comprises a second layer 114 and the embodiment displayed in Fig. 3b additionally comprises a third layer 115.

[0041] In one embodiment, the shaft 110 comprises a metal layer. The metal layer may for example be a steel layer, or an aluminum layer. Preferably, the metal layer is a corrosive resistant metal. Preferably, the metal layer is made of a metal having an average or above average thermal conductivity. In one embodiment, the shaft 110 comprises the metal layer as an outermost layer, that is, corresponding to an outer surface of the shaft 110. The metal layer improves the heat transfer from the heating means 130, such that heat losses are decreased. Furthermore, the metal layer provides rigidity to the shaft 110. In one embodiment the metal layer has a thickness of 2-6 mm, preferably 3-5 mm. The thickness is an important parameter which determines the rigidity of the shaft 110. The shaft 110 needs to be sufficiently rigid to maintain its own weight without bending. The thickness furthermore determines the resistance to dents. A dented surface may decrease the heat transfer from the heating means 130 to the shaft 110.

[0042] In one embodiment, the shaft 110 comprises a polymer layer. The polymer layer may for example be a fluoroplastic layer, such as a PTFE layer, or a polymer known under the trade name TEFLON. In one embodiment, the shaft 110 comprises the polymer layer as an innermost layer. The polymer layer decreases friction between the shaft 110 and the feed screw 120 such that the feed screw 120 moves smoothly in the shaft 110. Decreased friction also decreases the risk of spark formation, which provides a safer arrangement 100 with decreased risk of explosions. In one embodiment, the polymer layer has a thickness ≤ 20 micrometers, preferably < 20 micrometers.

[0043] In one embodiment, the shaft 110 comprises a bearing layer. The bearing layer may for example be a ceramic layer, for example an aluminum oxide layer. The bearing layer transfers heat from the heating means 130 to the material inside the shaft 110. The bearing layer is preferably arranged within the metal layer, wherein the bearing layer transfers heat from the metal layer to the material inside the shaft 110. In one embodiment, the shaft 110 comprises the bearing layer as an innermost layer. In an alternative embodiment, the shaft 110 comprises the bearing layer as an intermediate layer, for example arranged between the metal layer and the polymer layer. The bearing layer provides wear resistance to the shaft 110. In some embodiments, the feed screw 120 is arranged in contact with the shaft 110 and thus rotates against and in contact with the shaft 110. As such, the shaft 110 needs to be resistance to wear. Specifically, the shaft 110 needs to have an inner layer with a hardness above that of the feed screw 120, to increase wear resistance. For example, in a case where the feed screw 120 is made of a metal, such as steel, the shaft 110 is provided with a layer having a higher hardness than steel, such as aluminum oxide. In one embodiment, the bearing layer has a thickness of 20-1000 micrometer, preferably 100-500 micrometer, more preferably 300 micrometers.

[0044] The term shaft 110 should not be understood as limiting to the scope of the disclosure. The shaft 110 may also be referred to as a duct or a conduit or a pipe. Furthermore, the shaft 110 may have any cross-sectional shape, such as circular or rectangular, or combinations thereof, such as a circular bottom half and another geometry for the upper half.

[0045] Embodiments of the heating means 130 are described below.

[0046] The heating means 130 is provided outside the shaft 110, and is arranged to heat the arrangement 100. Specifically, the heating means 130 is arranged to, directly or indirectly, heat the shaft 110 and the feed screw 120. The heating means 130 has the effect that the material inside the shaft 110 is heated and thus residual water in the material is evaporated and thus the material is dried.

[0047] In one embodiment, the heating means 130 comprises heat cords, such as metal cords heated by electrical resistance. The heat cords are preferably arranged in direct contact with an outer layer of the shaft 110. With reference to Figs. 1a and 1b, the heat cords are arranged along a lengthwise extension of the shaft 110, and arranged in a wavy pattern. Alternatively, as displayed in Figs. 2a and 2b, the heat cords are wound around the shaft 110. The heat cords are arranged to evenly distribute heat over the mantle surface of the shaft 110. As such, the patterns displayed in Figs. 1a, 1b, 2a and 2b are not limiting to the scope of the disclosure.

[0048] In an alternative embodiment, the heating means 130 comprises a heating mantle. A heating mantle provides a heated liquid which encloses the shaft 110, or part of the shaft 110, for heating thereof. The heated liquid may for example be oil or a gas. Heating mantles are known to the skilled person. For example, it may be advantageous to utilize excess heat from another process a heating mantle where there is access to which can be used to heat the liquid.

[0049] In an alternative embodiment, the heating means 130 is an induction heating means 130, arranged to inductively heat the arrangement 100. In one embodiment, the feed screw 120 is heated by the induction heating means 130. In one embodiment, the shaft 110 is heated by the induction heating means 130, and the screw is heated by the shaft 110 through conduction.

[0050] In one embodiment, the arrangement 100 comprises an insulation outside the heating means 130. The insulation provides that the arrangement 100 is safer and more energy efficient.

[0051] Embodiments of the feed screw 120 are described below.

[0052] The feed screw 120 is arranged to be heated by the heating means 130 and may thereby dry the material which it is feeding through the shaft 110. The material to be dried is transported through the shaft 110 by means of the feed screw 120. The feed screw 120 is arranged to rotate inside the shaft 110. To this end, the arrangement 100 further comprises an electrical rotation unit (not shown), connected to the feed screw 120 and arranged to provide rotation of the feed screw 120. In one embodiment, the feed screw 120 rests on the bottom of the shaft 110.

[0053] In one embodiment the feed screw 120 is made by metal. The properties of the metal need to both enable the feed screw 120 to be rigid along its entire length, as well as having a sufficient heat conductivity. Preferably, the feed screw 120 is made by steel. In one embodiment, the feed screw 120 is a shaftless feed screw 120. A shaftless feed screw 120 is suitable for transport of low bulk density materials.

[0054] The arrangement 100 preferably also comprises means for removal of water leaving the material during drying. This prevents water condensing back onto the material.

[0055] As the feed screw 120 transports the material forward through the shaft 110, the material tends to fill the bottom half of the shaft 110 due to gravity, while the upper half remains empty. As the material is heated and residual water in the material is vaporized, the hot steam accumulates in the upper half of the shaft 110. The water should thus preferably be removed, to prevent the water from condensing back onto the material.

[0056] In one embodiment the water is removed by directing an air flow through the shaft 110, flowing in a direction opposite the feeding direction of the material in the shaft 110. To this end, dry air enters the shaft 110 through a dry air inlet 116 (seen in Fig. 4) near a material outlet 112 of the shaft 110. The dry air, when entering the shaft 110, preferably has a moisture level of essentially 0%. When the air exits the arrangement 100, the air has a moisture level > 0%. The air flow provides an efficient removal of moisture. Furthermore, since the material has a low bulk density, the air not only flows through any open space in the shaft, such as the upper half of the shaft 110, but flows through the material and provides removal of moisture throughout the entire volume of the material. This decreases the risk of local moisture pockets.

[0057] Fig. 4 displays a material handling system 200. The material handling system 200 may for example be arranged to transport a material to a compounding extruder, in which bio-composites are produced. The material handling system 200 may for example transport an organic material, such as an organic fiber, to be compounded together with a polymer in a compounding extruder to produce bio-composites.

[0058] The material handling system 200 in Fig. 4 comprises the arrangement 100, a first and a second auxiliary shaft 210, 211. The first and second auxiliary shaft 210, 211 each feeds material into the arrangement 100, through a first and second material inlet in the shaft thereof. The first and second auxiliary shaft 210, 211 are preferably for feeding different material into the arrangement 100. Alternatively, the material handling system 200 may comprise one or several auxiliary shafts for feeding material into the arrangement 100. Alternatively, the material may be inserted into the arrangement 100 in a different way than through an auxiliary shaft, such as manually inserted through a material inlet of the shaft.

[0059] The material may be an organic particle from a natural source such as forestry or an agricultural source. The organic particle may be an organic fiber, such as a reinforcing organic fiber. The organic fiber may be, but is not limited to, agriculturally sourced fiber, hemp fiber, cellulose fiber, or combinations thereof.

[0060] A method according to the present disclosure thus comprises feeding at least one material into the arrangement 100. The material when entering the shaft can for example have a moisture level > 5%, or > 10%, or > 20%.

[0061] The method furthermore comprises drying the material inside the shaft, during feeding of the material through the shaft.

[0062] The material is dried by heat provided from the arrangement 100, in that the arrangement 100 is heated and the heat is transferred to the material therein. In one embodiment, drying comprises reducing the moisture level in the material such that the moisture level is essentially 0% when exiting the arrangement 100. In this embodiment, the arrangement 100 is preferably provided as a last drying step in the material handling system 200, before the material moves to the next processing step such as a compounder. In an alternative embodiment, drying comprises reducing the moisture level in the material such that it is has a predetermined moisture level when exiting the arrangement 100. In this embodiment, the arrangement 100 is preferably provided as an intermediate drying step in the material handling system 200.

[0063] In one embodiment, the method comprises transferring heat to the material by thermal conduction from the arrangement 100. This is preferably achieved by the material being in direct contact with the inside surface of the heated shaft and / or the heated feed screw. There are several advantages with heating the material in this manner. One advantage is that the thermal conduction between two solid materials, such as metal and organic fiber, is more efficient than thermal conduction between a solid and a gas, such as air and organic fiber. Another advantage is that the material may reach a temperature which is higher than the surrounding air in the shaft. In some material handling systems, there is a maximum temperature of the air surrounding the material, for example for safety reasons to prevent spark formation and explosions. As such, by heating the material by thermal conduction from the (solid) arrangement 100, instead of heating through a heated gas such as warm air, the material can safely reach a temperature above the maximum allowed air temperature. In one embodiment, the material has a temperature ≥ 100°C when it is inside the arrangement 100. In one embodiment, the air inside the arrangement 100 has a temperature below 100°C, preferably below 70°C, more preferably below 60°C even more preferably 10-50°C, even more preferably 20-40°C, most preferably 30-35°C. In one embodiment, the dry air has a temperature when entering the dry air inlet being below 100°C, preferably below 70°C, more preferably below 60°C even more preferably 10-50°C, even more preferably 20-40°C, most preferably 30-35°C. In one embodiment, the dry air has a temperature when exiting the arrangement 100 being below 100°C, preferably below 70°C, more preferably below 60°C.

[0064] Feeding the material may comprise continuously feeding material. Feeding material may also comprise sequential feeding, that is, a combination of feeding and pausing, to ensure the material is sufficiently dry when exiting the arrangement 100. Feeding the material may comprise feeding at different feeding rates or a constant feeding rate.

[0065] In one embodiment, the method comprises directing an air flow through the shaft in a direction being opposite of a feeding direction of the material.

[0066] In an exemplary embodiment, the material handling system 200 further comprises an air flow generator 212. The air flow generator 212 is arranged to provide a flow of dry air into the dry air inlet 116 of the arrangement. The air flow generator 212 is furthermore arranged to provide a flow of dry air in a direction opposite of a feeding direction of the material through the shaft. The air flow generator 212 may furthermore comprise an air dryer for removing moisture, such that the air which flows through the dry air inlet has a moisture level of essentially 0%.

[0067] In all embodiments according to the present disclosure, when reference is made to a metal, this should be understood as either a pure metal or a metal alloy.

[0068] Preferred embodiments of an arrangement, a system and a method 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.

[0069] 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

[0033]In the following, a detailed description of the different embodiments of the invention will be disclosed under reference to the accompanying drawings. All examples herein should be seen as part of the general description and are therefore possible to combine in any way in general terms. Individual features of the various embodiments may be combined or exchanged unless such combination or exchange is clearly contradictory to the overall function of the system.

[0034]In Figs. 1a, 1b, 2a and 2b, there is displayed an arrangement 100 according to the present disclosure. The arrangement 100 generally comprises a shaft 110, a feed screw 120 arranged in the shaft 110, and a heating means 130 arranged outside the shaft 110.

[0035]The arrangement 100 according to the present disclosure is arranged to both transport material, and simultaneously dry the material as it is transported. The arrangement 100 is preferably part of a material handling system, such as for material components for c...

Claims

1. An arrangement (100) for feeding and drying a material, the arrangement (100) comprising: a shaft (110) for transport of the material, a feed screw (120) arranged in the shaft (110) for feeding the material through the shaft (110), a heating means (130) provided outside the shaft (110) and arranged to heat the arrangement (100) to dry the material in the shaft (110).

2. Arrangement (100) according to claim 1, wherein the shaft (110) comprises at least two layers of different materials, wherein at least one layer is chosen from a metal layer, a ceramic layer and a polymer layer.

3. Arrangement (100) according to claim 2, comprising a metal layer as an outermost layer, and a ceramic layer adjacent the metal layer.

4. Arrangement (100) according to any one of the preceding claims, wherein the heating means (130) is arranged in contact with an outside surface of the shaft (110).

5. Arrangement (100) according to any one of the preceding claims, wherein the feed screw (120) is arranged in contact with an inside surface of the shaft (110).

6. Arrangement (100) according to any one of the preceding claims, wherein the heating means (130) is arranged to heat the shaft (110) and / or the feed screw (120) by thermal conduction.

7. Arrangement (100) according to any one of the preceding claims, wherein the heating means (130) comprises heat cords heated through resistive heating.

8. Arrangement (100) according to any one of the preceding claims, further comprising a dry air inlet (116) through which dry air is arranged to flow into the shaft (110) and in a direction being opposite of a feeding direction of the material through the shaft (110).

9. A method for feeding and drying a material, the method comprising: feeding a material through a shaft (110) by means of a feed screw (120), heating the shaft (110) and the feed screw (120) by means of a heating means (130) arranged outside the shaft (110), wherein the material is dried by being heated by the shaft (110) and feed screw (120).

10. Method according to claim 9, wherein the heating means (130) heats the feed screw (120) through thermal conduction via the shaft (110).

11. Method according to claim 9 or 10, wherein the material is heated by thermal conduction from the shaft (110) and feed screw (120).

12. Method according to any one of claims 9-11, further comprising directing an air flow through the shaft (110) in a direction being opposite of a feeding direction of the material, wherein a moisture level of the air is essentially 0% when entering the shaft (110).

13. Method according to any one of claims 9-12, wherein the material has a temperature ≥ 100°C inside the shaft (110).

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