EP1630264A1 - 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.

The document EP 0 744 477 B1 describes a process for defibering / decortication of bast fiber plants, wherein the starting material is pre-shredded before defibering / decortication, such that the starting material is pre-shredded into pieces of pourable and / or free-flowing consistency and these pieces then defibred 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.

The document DE 199 25 134 A1 describes a method for producing random fiber material from plant parts, in which harvested crop presented in a first working step is taken from a supply stack, in a second working step a material strand with predominantly two-dimensional orientation of the plant parts is formed, in a third Operation of the formed material strand is performed 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 help of the series arrangement of coarse digestion devices and Feinaufschlußeinrichtungen the opportunity is created to selectively influence the fiber fineness and the shives size by the precomminuted starting material is subjected to several digestion procedures along the processing line, with coarse closure devices and Feinaufschlußeinrichtungen in the series arrangement depending on the application can be combined with each other. 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 temporary storage 4, the pre-shortened starting material 3 can be dispensed in doses to 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 spiraling lines around the shaft 11 are longitudinally adjacent to the shaft 11 and circumferentially 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)

Apparatus for defibering bast fiber plants, in particular annual plants such as flax, hemp, kenaf, oil and jute, with a comminuting device (2) for pre-comminuting a starting material (1) and a temporary store (4) in which the pre-comminuted starting material (3) is taken up and removed where the pre-comminuted starting material (3) is delivered for a metered feed to a downstream processing path for fiber defibration and for separation of fiber portions and shives, characterized ge - indicates that along with the pre-comminuted starting material (3) loaded processing line dosed a series arrangement of several coarse defibration devices (6, 8) and a plurality of Feinaufschlußeinrichtungen (7, 9, 10) is formed. Device according to Claim 1, characterized in that one of the plurality of coarse digestion devices (6, 8) and one of the plurality of fine digestion devices (7, 9, 10) are arranged alternately along the processing path. Apparatus according to claim 1 or 2, characterized in that there are provided along the processing line screens and / or classifier. Device according to one of the preceding claims, characterized in that the plurality of coarse digestion devices (6, 8) each have a Drum (6a, 8a) and in the drum (6a, 8a) arranged rotatable striking elements (6b, 8b) for processing the pre-shredded starting material (3), wherein the rotatable striking elements (6b, 8b) arranged on a shaft (11) and are designed pivotally. Apparatus according to claim 4, characterized in that the rotatably mounted impact elements (6b, 8b) pivotally mounted on a shaft housing and about an axis parallel to the central axis of the shaft (11) are pivotable. Apparatus according to claim 4 or 5, characterized in that the rotatably mounted impact elements (6b, 8b) are scoop-shaped. Apparatus according to claim 6, characterized in that the paddle-shaped striking elements (6b, 8b) have at a distal end to the shaft (11) a blade surface which is in a direction along the shaft (11) and / or in a direction transverse to the shaft (11). 11) is curved. Device according to one of claims 4 to 8, characterized in that the rotatably mounted impact elements (6b, 8b) on the shaft (11) along one or more in the longitudinal direction of the shaft (11) extending spiral line (s) are arranged. Device according to one of claims 4 to 8, characterized in that the rotatably mounted impact elements (6b, 8b) have an outer striking surface with blunt edges. Device according to one of claims 4 to 9, characterized in that a plurality of longitudinally extending impact elements (6d, 8d) are arranged on an inner wall (6c, 8c) of the drum (6a, 8a). A process for defibering bast fiber plants, in particular annual plants such as flax, hemp, kenaf, oil 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 a temporary storage device (4) , metered from the intermediate storage (4) to a downstream processing section and processed along the processing line for fiber pulping and separating fiber components and shives, characterized in that the pre-shredded starting material (3) is arranged along the processing line in a series arrangement of several coarse pulping devices ( 6, 8) and a plurality of fine disintegration means (7, 9, 10) is processed. Method according to claim 11, characterized in that the starting material (1) is pre-shredded in the comminution device (2) into pieces having a length of about 80 mm to about 120 mm. A method according to claim 11, characterized in that the starting material (1) is pre-shredded in the comminution device (2) into pieces having a length of about 120 mm to about 160 mm. A method according to claim 11, characterized in that the starting material (1) is pre-shredded in the shredding device (2) into pieces having a length of about 160 mm to about 200 mm. Method according to one of claims 11 to 14, characterized in that the fiber portions and the shives are separated along the processing path by sieving and / or sifting. Method according to one of claims 11 to 15, characterized in that the pre-shredded starting material (3) in the plurality of coarse digestion devices (6, 8) each in a drum (6a, 8a) with in the drum (6a, 8a) arranged rotatable striking elements (6b, 8b) is processed, wherein the rotatable striking elements (6b, 8b) on a shaft (11) arranged and are designed to pivot. A method according to claim 16, characterized in that the comminuted starting material (3) in the drum (6a, 8a) is machined by means of an outer striking surface of the striking elements (6b, 8b), wherein blunt edges are formed in the region of the outer striking surface. Method according to claim 16 or 17, characterized in that the pre-shredded starting material (3) in the drum (6a, 8a) is thrown against a plurality of longitudinally extending impact elements (6d, 8d) resting on an inner wall (6c, 8c) of the drum (6a, 8a) are arranged.

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