EP1630264B1 - Device and method for defibrating bast fibre plants - Google Patents

Abstract

An intermediate storage unit (4) stores pre-comminuted starting material (3) from a comminution device (2). The starting material is fed into a downstream processing section for releasing fibers. An independent claim is also included for method for processing fiber from fiber plants.

Description

The invention relates to an apparatus and a method for defibering bast fiber plants, especially annual plants, such as flax, hemp, kenaf, oil and jute.

Renewable resources are becoming increasingly popular as they not only conserve existing resources, but also contribute to reducing the CO ₂ known as greenhouse gas. Both the fiber portions and the so-called shives, which are the woody portions of bast fiber plant stems, are used in a variety of applications. Therefore, methods and apparatus have been developed for separating the fiber portions and the shives from a source material. This process is often referred to as defibration or undoing. Here, the starting material is subjected to a process of fiber pulping, and then fiber portions and shives are separated.

In the processing of annual plants such as flax or hemp, the objective is to adapt the property profile of the fiber produced to products to be subsequently produced using the fibers and their requirements by means of a suitable pulping method. Due to these requirements, digestion processes have gained in importance in recent years, in which so-called "green" starting materials are used. The difference to traditional digestion methods lies in the field roast, whereby the plant after the cut only a few days left to dry in the field to achieve the necessary for a storage residual moisture content of <18%. In contrast, for traditional pulping process starting materials are required, which remain on the field for a long time, whereby weather-related and bacterial effects lead to embrittlement, to achieve by kinking operations in fiber pulping easier separation of the fiber from the other plant components. The plant itself consists predominantly of cellulose, hemicellulose, pectin, lignin, water-soluble substances and low levels of fat and wax.

The fibers of the plant consist of fiber bundles. These have a different bundle length depending on the type of fiber. In hemp this is between about 650mm and about 3500mm, with flax between about 100mm and about 1400mm. The individual fiber in the fiber bundle is connected by means of putty substances (pectin) with the other fibers. In order to obtain certain properties for later applications, it is therefore necessary to dissolve these fiber bundles to a desired fineness level. This is much more difficult with the green plant, since degradation of the pectins by the short field storage has taken place only to a small extent. In contrast, however, the high strength properties have been largely retained.

The dissolution of the fiber bundles leads to a shortening of the fiber. It should be noted that the fiber cell of hemp has a length of about 10mm to about 50mm and that of flax has a length of about 5mm to about 70mm. This means that with higher fiber pulping and accordingly finer fiber a reduction is connected, which theoretically comes close to the length of the single cell.

In order to achieve a resolution of the plant bundles with green starting material, a high energy input is required. Therefore, in the state of the art for this purpose high-speed units are used, which by impact, bending and shearing stress lead to a resolution of the fiber bundles. Hammer mills or high-speed, turbine-type pulping plants are preferably used. Fibers from aggressive processing fiberize from a coarse bast into many individual fibers and fibrils. This leads to Knäulbildungen and matted structures with a large spread in the fiber length. Such high-speed systems lead to the disadvantages described. In addition, the high energy input takes place in one stage, in which case the resolution of the fiber bundles is influenced by varying the design of the impact elements and the rotational speed.

In the document EP 0 744 477 B1 there is described a process for defibering / decortication of bast fiber plants, wherein the starting material is pre-shredded prior to defibering such that the raw material is pre-shredded into pourable and / or pourable consistency pieces and then defibered in a high speed rotating mill. The subsequent separation of fibers and shavings is carried out with the aid of sieves and / or classifiers, whereby the fibers can also be simultaneously classified and fractionated by length, and oversize particles, dust and foreign bodies can be removed. Defibration takes place on account of the impact of impact and / or friction and / or shear in the high-speed rotating mills used. The fibers produced by means of this method preferably have a length of between 1 mm and 100 mm, in particular between 2 mm and 50 mm.

From the document DE 38 15 771 A1 is a processing machine for fiber plants known. The conditioning machine comprises a breaking device consisting of at least one pair of profiled crushing rollers for the woody outer layer of the fiber plants. The breaking device is followed by a decortical device. The Entholzungsvorrichtung may consist of paired, sprung and coarsely profiled on the outside conveyor belts, of which the upper conveyor belts perform in addition to their longitudinal movement nor a periodic transverse movement. As a result, the broken wood parts are released from the fibers and embedded in the groove of the profiles. In another embodiment, a Conveyor belt and a conveyor drum combined with each other or two conveyor belts, which rotate at an acute angle to each other.

The document US 5,507,074 discloses a method of crushing a material, such as kenaf, to separate bast from the core. The manufactured length of the crushed material is typically 3 to 5 inches (7.5 to 12.5 cm).

The document FR 1,066,514 describes a device having a plurality of rotating elements for processing fiber materials of plants, for example hemp plants.

Furthermore, according to Article 54 (3) EPC, the prior art is apparent from the document DE 103 31 731 A1 , This document discloses an apparatus for separating the outer fiber layers from the cores of hemp plants forming cores. In the known device, the hemp plants pressed into a bale are formed into a plant strand by means of a roller system. It is explained that the plants are cut, for example, into sections with a length of about 60 cm. By means of conveyor belts, these plant sections are guided past separating or peeling rotors, each separating rotor being provided with a plurality of rows of peeling knives which are arranged at a relatively small distance in the axial direction. The peeling blades are crescent-shaped in one embodiment. In the specified length of the plant sections in the practical implementation of the risk that the plant sections wrap around parts of the peel rotors, which can lead to damage to the system, possibly even an increased fire hazard. In addition, an effective fiber pulping appears hardly possible in this way. After separation of the fibers from the shives they are to be crushed by a chopper.

In the document DE 199 25 134 A1 a method for producing tangled fiber material from plant parts is described, in which in a first step submitted crop is taken from a supply stack, in a second step, a material strand is formed with predominantly two-dimensional orientation of the plant parts is performed in a third step, the formed material strand in the work area of a treatment station, in a fourth step, the simultaneous crushing, fiberizing and separating fibers and non-fibrous components (shives) is made and in a fifth Working step, the separate removal of the random fiber material and the non-fibrous plant components takes place. In the known methods, it is possible to carry out at least the procedures of breaking up the plant parts, discharging the material fractions produced and after-treatment of the random fiber material. The simultaneous comminution, fiberizing and separating of the fibers and the shives in a processing station can be repeated by arranging at least two processing stations in a series connection. The workstations have percussion tools with blunt hammer surfaces which serve to break up the plant parts and, to a lesser extent, separate the fiber components from the shives.

The object of the invention is to provide an improved apparatus and an improved method for defibering bast fiber plants, in particular of annual plants, in gentle processing stages in which the efficiency of the separation of fiber fractions and shives is increased. Moreover, it is an object of the invention to increase the proportion of fibers and / or shives with predetermined properties for further processing, in particular with a predetermined length.

This object is achieved by a device according to independent claim 1 and a method according to independent claim 11.

A device for defibering bast fiber plants, in particular annual plants such as flax, hemp, kenaf, oil and jute, with a comminution device for pre-comminuting a starting material and a buffer in which received the pre-shredded starting material and from which the pre-shredded starting material for a metered supply to a downstream Processing section for fiber pulping and separating fiber fractions and shives is discharged, wherein along the metered with the pre-shredded starting material processing section a series arrangement of a plurality of coarse digestion devices and a plurality of Feinaufschlußeinrichtungen is formed.

With the aid of the series arrangement of coarse digestion devices and fine digestion devices, it is possible to selectively influence the fiber fineness and the size of the shives by subjecting the pre-shredded starting material to several digestion procedures along the processing line, whereby coarse digestion devices and fine digestion devices in the series arrangement can be combined as desired with one another depending on the application. It is a cascade editing procedure allows in which the arrangement of the coarse digestion and the Feinaufschlußeinrichtungen can be adapted to separate fiber components and shives with predetermined properties for further processing.

An expedient embodiment of the invention provides that one of the plurality of coarse digestion devices and one of the plurality of fine digestion devices are arranged alternately along the processing path, whereby an alternating coarse / fine digestion of the comminuted starting material can be carried out.

Combined with the plurality of coarse digestion devices and the plurality of Feinaufschlußeinrichtungen can be provided in an embodiment of the invention in the array sieves and / or classifier, which serve for separating fiber components and shives along the processing line and / or at the end of the processing section. This can be done at the same time a classification and fractionation on the length of the fiber components / shives.

Appropriately, it can be provided that the plurality of coarse digestion devices each have a drum and arranged in the drum rotatable impact elements for processing the pre-shredded starting material, wherein the rotatable impact elements are arranged on a shaft and designed to be pivotable. The impact elements are rotated to edit the material by means of a shaft in the drum and lead here because of the pivotal arrangement pivoting movements. The use of such coarse digestion facilities has the Advantage that in this way compared to known high-speed rotating mills, such as hammer mills, more cost-effective way to coarse pulping of the starting material by shear, friction, impact and / or shock is created.

In one embodiment of the invention can be provided that the rotatably mounted impact members are pivotally mounted on a shaft housing and about an axis parallel to the central axis of the shaft are pivotable. In this way, hammer-like working impact elements are formed, which additionally pivot about an axis formed outside the central axis of the shaft when turning the shaft in the drum and thus work as a mallet.

In order to improve the energy input to the processed material in the coarse pulper, an embodiment of the invention provides that the rotatably mounted impact elements are blade-shaped. In this way, in particular, it is achieved that the impact and entrainment effect which the impact elements exert on the material to be processed is improved.

In one embodiment of the invention can be provided that the paddle-shaped striking elements have at a distal end to the shaft a blade surface which is curved in a direction along the shaft and / or in a direction transverse to the shaft, thereby further improving the transport of processing material is achieved in the coarse pulper. It can be provided that the blade surfaces of impact elements in the longitudinal direction of the shaft adjacent and offset in the circumferential direction of the shaft are arranged so that a substantially closed surface is formed when these striking elements would be moved to a straight line in the longitudinal direction of the shaft. The number and distribution of the impact elements on the shaft can also be chosen so that several times a substantially closed surface is formed. With the help of essentially closed surface of the energy input is optimized for the material to be processed.

The running properties of the coarse digestion device are improved in an expedient development of the invention in that the rotatably mounted impact elements are arranged on the shaft along one or more spiral lines extending in the longitudinal direction of the shaft. It can be provided that the rotatably mounted impact elements are positioned substantially along a spiral line extending around the shaft. The impact elements may be arranged each suitably laterally offset to such a circumferential spiral line, so that they are positioned substantially along a spiral circumferential zigzag or curved line. The arrangement along the spiral line prevents a pulsating operation, so that a higher stress of bearing elements is avoided. In addition, this ensures that no plant material sets and it comes to winding phenomena around the shaft.

A development of the invention may provide that the rotatably mounted impact elements have an outer striking surface with blunt edges. The blunt formation of the edges avoids when processing the crushed starting material, that too unwanted cutting action results in the digestion of the starting material. In addition, the impact effect is improved with the help of these embodiments.

In order to increase the residence time of the pre-shredded starting material in the drum, which leads to an improved digestion and separation effect in the individual coarse digestion devices, an embodiment of the invention provides that a plurality of longitudinally extending impact elements are arranged on an inner wall of the drum. The baffles may be, for example, angular or U-shaped baffles in which angled portions protrude from the inner wall.

It can be provided that the starting material in the comminution device is pre-shredded into pieces having a length of about 80 mm to about 120 mm, more preferably to a length of about 120 mm to about 160 mm and particularly preferably to a length of about 160 mm to about 200 mm. In this way it is achieved, on the one hand, that the starting material is pre-comminuted to a desired initial length, which in turn substantially influences the length of these constituents obtained during digestion and separation of fiber fractions and shives. Pre-shredding to such lengths also facilitates automated processing of the pre-shredded feedstock along the processing line in the plurality of coarse digestion devices and the plurality of fine digestion devices.

By pre-crushing is also achieved that the separated in the course of the processing fiber portions after the digestion of the pre-shredded starting material have a length and fiber fineness, which ensure when using the fiber content in insulation products, such as insulation boards, the heat conductivity necessary for the insulation effect. The described method for separating the fiber components can thus be used advantageously in conjunction with a method for producing an insulating product, in particular an insulating panel, such that the separated fiber components in a processing section downstream processing station with a base material, such as a plastic, mixed and to a Molded body.

The invention is explained below with reference to embodiments with reference to a drawing. Here, the single figure shows a schematic representation of an apparatus for defibering bast fiber plants, in particular renewable raw materials.

According to the figure, a starting material 1 is fed to a comminution device 2. The starting material 1 is a stock of bast fiber plants, such as flax, hemp, kenaf, oil or jute. The starting material 1 is comminuted in Halmabschnitte uniform or approximately uniform length, namely pre-shortened. The starting material 1 is preferably at a length of about 80mm to about 120mm, more preferably a length of about 120mm to about 160mm, and most preferably a length of about 160mm to about 200mm pre-shortened and then fed to the buffer 4.

From the buffer 4, the pre-shortened starting material 3 can be dispensed dosed on a conveyor 5, which serves to supply the pre-shortened starting material 3 a downstream processing section for unlocking and separating fiber fractions and shives. The pre-shortened starting material 3 is fed via the conveyor 5 to a first dynamic digestion unit, which is a coarse digestion device 6, in which the pre-shortened starting material 3 is subjected to coarse digestion. In this processing stage, a first coarse separation of fibers and shives takes place. The coarse digestion device 6 has a partially open lateral surface. In the open area of the lateral surface both an inlet opening for the intake of the material to be processed in the coarse pulper 6 and an outlet opening for discharging the processed material are formed, whereby a simplified structural design is achieved. Due to the centrifugal force, the machined material is thrown onto the conveyor 5 through the outlet opening, whereby a continuous removal is achieved.

Within the drum-shaped lateral surface, a rotor is arranged, which is expediently formed by means of a shaft and equipped with blunt flat and / or curved striking elements. The number of these impact elements on the rotor can be designed variably. The striking elements are preferably along the rotor one or more extending around the rotor spiral lines arranged as individual elements on a rotatable shaft.

Subsequently, the separated shives are sieved through a sieving line. The coarse digestion device 6 is followed by a fine digestion device 7, which is followed by a further coarse digestion device 8. Thereafter, the comminuted starting material 3 is processed in two further Feinaufschlußeinrichtungen 9, 10. Along the processing line sieves / classifiers (not shown) can be combined with the coarse digestion devices 6, 8 and the fine digestion devices 7, 9, 10, which serve to separate the fiber portions and shives. The arrangement of the coarse digestion devices 6, 8 and the fine digestion devices 7, 9, 10 shown in the figure is exemplary. Depending on the application, a combination of the devices in the series arrangement can be selected.

The coarse digestion devices 6, 8 are formed by means of a respective dynamic digestion device, which has a drum 6a, 8a and in the drum 6a, 8a rotatably mounted impact elements 6b, 8b. The striking elements 6b, 8b made scoop or paddle-shaped and mounted on a shaft 11 which serves to turn the striking elements 6b, 8b in the drum 6a, 8a. Here, the impact elements 6b, 8b are pivotally mounted on the shaft 11 so that they can perform 11 additional pivoting movements during rotation of the shaft. In addition, this type of attachment allows a time-saving and cost-effective replacement.

The impact elements 6b, 8b are preferably distributed along one or more spiral lines extending in the longitudinal direction of the shaft 11. In this way, the largest possible working width is created, which can extend for example over several meters, which allows a high throughput.

Blade or paddle surfaces of the impact members 6b, 8b are preferably dimensioned so that the paddle surfaces of impact members distributed along one or more of the spiral lines around the shaft 11 are adjacent in the longitudinal direction of the shaft 11 and in the circumferential direction the shaft are offset from each other and thus a substantially closed surface is formed when these striking elements would be moved to a straight line in the longitudinal direction of the shaft 11. The number and distribution of the impact elements 6b, 8b on the shaft 11 can also be chosen so that a substantially closed surface is formed several times. With the help of the substantially closed surface of the energy input is optimized for the material to be processed.

On an inner wall 6c, 8c of the lateral surface a plurality of baffles 6d, 8d are arranged, which are preferably formed as profiled retaining strips and serve to extend the residence time of the crushed starting material 3 in the respective drum 6a, 8a, which allows an increased energy input, thereby the defibration / decortication carried out by means of shear, friction, impact and / or impact is carried out more effectively. The number and the distance of the baffle elements 6d, 8d, which are preferably fixed on the inner wall 6c, 8c, can be designed variably. The plurality of baffles 6d, 8d may be angular or U-shaped elements in which angled legs project from the inner wall 6c, 8c. The rotatably mounted impact elements 6b, 8b have an outer striking surface with one or more blunt edges.

The fine disintegration devices 7, 9, 10 each have static and rotating comb elements which engage in a spaced manner when the rotating comb elements are guided past the static comb elements during rotation.

The pulping method described in connection with the embodiment can be summarized as follows. In the coarse digestion 6 takes place a first rough separation of fibers and shives. Subsequently, the separated shives are sieved through a sieving section (not shown). Siebstrecken are known as such and are therefore not explained here. The residual fraction is fed to the fine digestion device 7. In this machine unit comb-like segments are included, which are arranged statically and rotationally and lead by means of interlocking comb elements to a separation of adhering shives and pre-dissolved fiber bundles. The detached shives are then screened and the remaining material for a coarse digestion of the other coarse digestion device 8, which is comparable to the coarse pulper 6, respectively. As a result of the separation of partial quantities (shives) which has taken place in the preceding steps, a significantly reduced amount of material is supplied to this processing station, so that the energy input for the coarse digestion only has an effect on the remaining fiber bundles and on the fiber bundles with shives not yet detached therefrom. It follows the further Feinaufschlußeinrichtung 9 with subsequent Siebstrecke. This fibrous material is then fed to the fine disintegrator 10 for separation of the shives. After this processing stage, the fibers have a high resolution with low residual shives content. If necessary, further fine digestion units and / or screening sections can follow the fine digestion device 10.

The features of the invention disclosed in the foregoing description, in the claims and in the drawing may be of importance both individually and in any combination for the realization of the invention in its various embodiments.

LIST OF REFERENCE NUMBERS

1

starting material

2

comminution device

3

pre-shredded starting material

4

cache

5

Conveyor

6, 8

Coarse defibration device

6a, 8a

drum

6b, 8b

rotatably mounted impact elements

6c, 8c

Inner wall of the drum

6d, 8d

baffles

7, 9, 10

Fine defibration device

11

wave

Claims (18)

1. Device for defibration of bast fibre plants, particularly annual plants such as flax, hemp, kenaf, linseed and jute, with a comminuting device (2) for pre-comminution of a starting material (1) and an intermediate store (4) in which the pre-comminuted starting material (3) is received and from which the pre-comminuted starting material (2) is delivered for a metered feed to a downstream processing path for fibre defibration and for separation of fibre portions and shives, characterised in that a serial arrangement of several coarse defibration devices (6, 8) and several fine defibration devices (7, 9, 10) is formed along the processing path charged in metered manner with the pre-comminuted starting material (3).
2. Device according to claim 1, characterised in that one of the several coarse defibration devices (6, 8) and one of the several fine defibration devices (7, 9, 10) are arranged in alternation along the processing path.
3. Device according to claim 1 or 2, characterised in that sieves and/or sifters are provided along the processing path.
4. Device according to one of the preceding claims, characterised in that the several coarse defibration devices (6, 8) each comprise a drum (6a, 8a) and rotatable beater elements (6b, 8b), which are arranged in the drum (6a, 8a), for processing the pre-comminuted starting material (3), wherein the rotatable beater elements (6b, 8b) are arranged at a shaft (11) and executed to be pivotable.
5. Device according to claim 4, characterised in that the rotatably mounted beater elements (6b, 8b) are pivotably mounted at a shaft housing and are pivotable about an axis parallel to the centre axis of the shaft (11).
6. Device according to claim 4 or 5, characterised in that the rotatably mounted beater elements (6b, 8b) are shovel-shaped.
7. Device according to claim 6, characterised in that the shovel-shaped beater elements (6b, 8b) have at a distal end with respect to the shaft (11) a shovel surface which is curved in a direction longitudinally with respect to the shaft (11) and/or in a direction transversely with respect to the shaft (11).
8. Device according to one of claims 4 to 8, characterised in that the rotatably mounted beater elements (6b, 8b) are arranged at the shaft (11) along one or more spiral lines extending in longitudinal direction of the shaft (11).
9. Device according to claim one of claims 4 to 8, characterised in that the rotatably mounted beater elements (6b, 8b) have an outer beating surface with blunt edges.
10. Device according to one of claims 4 to 9, characterised in that several baffle elements (6d, 8d) extending in longitudinal direction are arranged on an inner wall (6c, 8c) of the drum (6a, 8a).
11. Method for defibrating of bast fibre plants, particularly annual plants such as flax, hemp, kenaf, linseed and jute, in which a starting material (1) is pre-comminuted in a comminuting device (2) and in which the pre-comminuted starting material (3) is received in an intermediate store (4), is fed from the intermediate store (4) in metered manner to a downstream processing path and is processed along the processing path for fibre defibration and for separation of fibre portions and shives, characterised in that the pre-comminuted starting material (3) is processed along the processing path in a serial arrangement of several coarse defibration devices (6, 8) and several fine defibration devices (7, 9, 10).
12. Method according to claim 11, characterised in that the starting material (1) is pre-comminuted in the comminuting device (2) into pieces with a length, of approximately 80 millimetres to approximately 120 millimetres.
13. Method according to claim 11, characterised in that the starting material (1) is pre-comminuted in the comminuting device (2) into pieces with a length of approximately 120 millimetres to approximately 160 millimetres.
14. Method according to claim 11, characterised in that the starting material (1) is pre-comminuted in the comminuting device (2) into pieces with a length of approximately 160 millimetres to approximately 200 millimetres.
15. Method according to one of claims 11 to 14, characterised in that the fibre portions and the shives are separated along the processing path by means of sieves and/or sifters.
16. Method according to one of claims 11 to 15, characterised in that the pre-comminuted starting material (3) is processed in the several coarse defibration devices (6, 8) in each instance in a drum (6a, 8b) by rotatable beater elements (6b, 8b) arranged in the drum (6a, 8a), wherein the rotatable beater elements (6b, 8b) are arranged at a shaft (11) and executed to be pivotable.
17. Method according to claim 16, characterised in that the comminuted starting material (3) is processed in the drum (6a, 8a) by means of an outer beater surface of the beater elements (6b, 8b), wherein blunt edges are formed in the region of the outer beater surface.
18. Method according to claim 16 or 17, characterised in that the pre-comminuted starting material (3) is centrifuged in the drum (6a, 8a) against several baffle elements (6d, 8d) which extend in longitudinal direction and which are arranged on an inner wall (6c, 8c) of the drum (6a, 8a).

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