EP3006174B1 - Method and system for manufacturing a wood fibre board - Google Patents

Description

The invention relates to a method and a plant for producing a wood fiber board from process-own wood fibers and process-foreign fibers.

Under process-own wood fibers thereby are understood such fibers, which are won and further processed in a per se uninterrupted manufacturing process at the wood fiber board manufacturer from a raw material such as wood chips. The non-process fibers are produced in an external production process and supplied to the manufacturing process only at the wood fiber board manufacturer.

• Zerfasern von zerkleinertem Rohmaterial zu prozesseigenen Holzfasern,
• Zugeben eines Bindemittels (Leim) zu den prozesseigenen Holzfasern,
• Trocknen der beleimten prozesseigenen Holzfasern,
• Streuen der prozesseigenen Holzfasern zu einem Faserkuchen und
• Verpressen des Faserkuchens zu einer Faserplatte.

In the production of wood fiber boards, process-own wood fibers are produced in the stationary process and processed into wood fiber boards. The process chain for production always comprises the following steps:

• Shredding of shredded raw material into process-own wood fibers,
• Adding a binder (glue) to the process-own wood fibers,
• Drying the glued process-own wood fibers,
• Sprinkle the process-own wood fibers into a fiber cake and
• Pressing the fiber cake to a fiberboard.

The production process at the given production location depends on a variety of local conditions, such as availability of wood, wood assortment, energy costs, Type of energy and / or the permit situation. This multifactorial dependence makes a cost-stable production difficult and thus always represents a certain economic risk for the manufacturer.

Wood as a raw material is available worldwide in different availabilities. One challenge is to transport it economically to its destination. It is known to transport wood chips, for example, by ship to the production site and further process there. The costs are comparatively high.

The EP 1 623 807 B1 describes a method for producing a wooden material body, in which wood material is cut into wood chips and in which filamentary fiber material is first comminuted into individual fibers. These fibers are then sprinkled into the wood chips and then a binder (glue) is applied at least to the wood chips. The fibers can also be collected first and then mixed with the wood chips. With the described method, the application of a binder is not technically feasible exclusively on the wood chips or at best with a huge technical effort, which leads to the fact that the fibers are glued. Furthermore, with this method, it is possible to introduce fibers specifically for influencing the mechanical properties, but complete distribution and good mixing of fibers and wood chips in a continuous production process is also possible only with unacceptably high outlay. The fiber cutting and Beleimvorrichtungen proposed for this purpose are structurally very complex, therefore expensive and complicated to handle.

In the DE 10 2006 062 285 A1 there is described a fiberboard and a method of making the same. Here, cellulose-containing fibers are first obtained from a vegetable material and process-external cellulosic fibers are provided from a recycled material such as paper, cardboard, cardboard or pulp. Subsequently, a binder is added to all fibers, the fibers are dried, a nonwoven fabric is formed and the nonwoven fabric is pressed into a wood fiber board. To provide the non-process fibers recycled waste paper is prepared as bales.

In the DE 10 153 175 A1 describes a method and a plant for the production of profiled molded parts comparable with real wood products. In the process delivered wood fiber bales are processed into workable fibers, dosed glued with a binder, molded into a defined web, precompressed, trimmed and pressed in a cover press to form a molding. For this purpose, it is intended to manufacture the molded parts completely from the fibers of the supplied wood fiber bales and to glue the entirety of the fibers.

In the WO 95/10402 A1 For example, a method of making articles from reinforced composite materials, including wood or cellulosic fibers and plastic, is described. The shredded wood fibers are mixed with plastic in a predetermined ratio. The composites form the main structural components of the finished article. The mixture is then sprinkled into a cake and pressed into a reinforced wood-based product. Reinforcing fibers may be added to the mixture before compression. During pressing, the plastic melts and combines with the wood fibers.

In the DE 12 35 573 B discloses a method in which only a portion of the chips is glued and these wet glued chips are then mixed with dry unglued chips. The mixture is sprinkled into a cake and then pressed.

From the US 5,641,819 A For example, a process is known in which initially smaller particles or fibers are glued and then mixed with larger and preferably unprimed components without adding glue again. Before the unembellished fibers are mixed with the glued fibers, the glued fibers can be partially cured. From the mixture, a wood-based panel or a fiberboard is then produced.

The known production processes for the production of wood fiber boards including process-foreign fibers provide all fibers to be glued. As a result, homogeneous strength properties of the end products are attained on the one hand in a technically simple manner while maintaining a high standard of quality. On the other hand, a higher proportion of binder (glue) is needed for this the manufacturing process is more expensive due to higher material and energy costs.

On this basis, a method for producing a wood fiber board from process-own wood fibers and process-foreign fibers is to be specified, with which a simple, simultaneously cost-reducing and safe production of wood fiber boards is made possible. Furthermore, a suitable for carrying out this process plant should be specified.

1. a) Zerfasern von Holzhackschnitzeln in einem Refiner zu prozesseigenen Holzfasern,
2. b) Transportieren der im Refiner erzeugten prozesseigenen Holzfasern in eine Beleimvorrichtung,
3. c) Beleimen der prozesseigenen Holzfasern mit einem Klebstoff,
4. d) Transportieren der beleimten prozesseigenen Holzfasern in einen Trockner,
5. e) Zuführen der unbeleimten prozessfremden Fasern in den Trockner, wobei die unbeleimten prozessfremden Fasern vor dem Zuführen aus verpressten Faserballen herausgetrennt werden,
6. f) Mischen der prozesseigenen Holzfasern und der prozessfremden Fasern zu einem Fasergemisch in dem Trockner,
7. g) Transportieren des Fasergemischs in eine Streuvorrichtung,
8. h) Streuen des Fasergemischs zu einem Faserkuchen,
9. i) Verpressen des Faserkuchens zu einer Holzfaserplatte gewünschter Dicke in einer Heißpresse.

The process for producing a wood fiber board from process-own wood fibers and process-foreign fibers is characterized by the following steps:

1. a) shredding wood chips in a refiner into process-own wood fibers,
2. b) transporting the process-own wood fibers produced in the refiner into a gluing device,
3. c) gluing the process-own wood fibers with an adhesive,
4. d) transporting the glued process-own wood fibers into a dryer,
5. e) feeding the non-sized non-process fibers into the dryer, wherein the non-sized non-process fibers are separated out from compressed fiber bales prior to feeding,
6. f) mixing the process-own wood fibers and the non-process fibers into a fiber mixture in the dryer,
7. g) transporting the fiber mixture into a spreading device,
8. h) spreading the fiber mixture into a fiber cake,
9. i) pressing the fiber cake into a fibreboard of desired thickness in a hot press.

From a conventional method for producing a wood fiber board, the inventive method differs in that the non-process fibers are not sized, are supplied in a dryer and mixed there with the process-own wood fibers. In this way, on the one hand, the required amount of adhesive can be reduced. On the other hand, an effective like simple supply of non-process fibers to the glued process-own wood fibers realized. In addition, a particularly short time sequence of the steps drying, mixing and transporting is achieved, which also reduces the space requirement of the production plant and its complexity.

The non-process fibers are preferably wood fibers. These wood fibers can be sourced from any of the world-wide manufacturers, especially from regions where criteria such as wood availability, the range of wood, the energy costs or the approval situation for the production process - especially in the economic sense - is particularly favorable. This is an advantageous way to reduce the local dependence of the wood fiber board manufacturer of said criteria.

It is preferably provided to supply the non-process fibers with a proportion of up to 20 wt .-% based on the fiber mixture. In this way it is achieved that the non-process fibers can be fed without glue, without having to accept qualitative deficits in the production of wood fiber board in purchasing. Beyond that going proportions of process-foreign fibers must preferably be fed to a separate gluing, for example, a dry gluing.

In a further advantageous embodiment of the method, the feeding of the non-process fibers via an air stream, which has the advantage that the process foreign fibers in the air stream further separated (isolated) takes place.

The non-process fibers are separated out before being fed from compressed fiber bales. These compressed fiber bales can also be made in the region with said favorable starting situation, taking advantage of said advantages. In this case, the fiber bales can be separated immediately before feeding the separated out of process fibers or have already been separated in a process outside the process. A high degree of flexibility combined with low economic outlay is made possible for the manufacturer.

In particular, when using wood fiber bales, consisting of non-wood fibers, the wood fiber bales are produced, for example, decentralized at a location that is particularly advantageous both in terms of the availability of wood as well as the availability of low-cost energy. The production chain for such wood fiber bales is designed such that initially round wood is crushed into wood chips, these are then washed and cooked and further digested in a refiner to process foreign wood fibers. These process-foreign wood fibers are then dried to a moisture content of 4-12%, preferably 6-9%, based on atro wood, finally pressed into wood fiber bales and optionally airtight and packaged safe transport, wrapped for example with foil or welded. The packaging can be done in a pressing device itself. The wood fiber bales are pressed to a density of 400-500kg / m ³ , which compresses them to an optimal size for transport to the intended board manufacturer. When rupturing such compacted wood fiber bales and largely separating the process-foreign wood fibers in a method according to the invention, the volume of wood fibers outside the process increases by a factor of 10.

It is furthermore conceivable to provide the dried, extraneous wood fibers with mold protection and / or swelling protection and / or to acetylate. As the acetylating agent, for example, acetic anhydride can be used, whereby a degree of acetylation of the process-foreign wood fibers of 3% to 30%, preferably 20%, is achieved and thus an insect or fungal attack can be largely excluded. A wood fiber bale produced by the method described is then transported to a wood fiber board manufacturer where it is processed, for example, in a process according to the invention and further processed. It is also conceivable, of course, to produce wood fiber boards exclusively from such wood fiber bales. The possibility of storage at any point subsequent to the manufacturing process is conceivable. The wood fiber bales need not be produced exclusively in specially designated manufacturing process, but the need to produce process-external wood fibers can also be from a per se uninterrupted wood fiber board manufacturing process, for example, overcapacities of a refiner, related and processed as already described to wood fiber bales.

Preferably, the dryer has a pre-dryer and a after-dryer, wherein the non-process fibers are supplied to the glued process-own wood fibers between the pre-dryer and the after-dryer. As a result, the drying parameters can be better adjusted to the glued process-own wood fibers and unprimed non-process fibers. In a single-stage dryer, the feeding can be done at any point, especially in the last third of the dryer section.

The glued process-inherent wood fibers are preferably dried in a pre-dryer before feeding the non-process fibers. In this way it is achieved that the moisture content of the glued process-own wood fibers, the humidity of the subsequently added process-external fibers is equalized. The formation of agglomerates is thereby advantageously largely avoided.

Preferably, the mixing of the process-own wood fibers and the non-process fibers in an air stream. As a result, all fibers are mixed in a technically simple way and transported simultaneously.

The drying of at least the process-own wood fibers preferably takes place in a stream of air, whereby at least the process-own wood fibers are dried and transported at the same time.

1. a. einem Refiner zum Aufschließen von Holzhackschnitzeln zu prozesseigenen Holzfasern,
2. b. einer Beleimvorrichtung zum Beleimen der im Refiner erzeugten prozesseigenen Holzfasern,
3. c. einem Trockner zum Trocknen zumindest der beleimten prozesseigenen Holzfasern und zum Mischen der beleimten prozesseigenen Holzfasern und der prozessfremden Fasern zu einem Fasergemisch,
4. d. einer in den Trockner führenden Zuführvorrichtung zum Zuführen der unbeleimten prozessfremden Fasern in den Trockner,
5. e. einer der Zuführvorrichtung vorgeordneten Auftrennvorrichtung zum Auftrennen von verpressten Faserballen, bestehend aus prozessfremden Fasern in weitgehend vereinzelte prozessfremden Fasern mit:
   • e₁. eine Aufreißvorrichtung zum Aufreißen der Faserballen,
   • e₂. eine Aufschlussvorrichtung zum Aufschließen der aufgerissenen Faserballen zu weitgehend vereinzelten prozessfremden Fasern,
6. f. Streuvorrichtung zum Streuen des Fasergemischs zu einem Faserkuchen,
7. g. einer Heißpresse zum Verpressen des Faserkuchens zu einer Holzfaserplatte gewünschter Dicke.

A plant for producing a wood fiber board from process-own and process-independent fibers according to the inventive method is characterized by the following features:

1. a. a refiner for breaking woodchips into process-own wood fibers,
2. b. a gluing device for gluing the process-own wood fibers produced in the refiner,
3. c. a dryer for drying at least the glued process-own wood fibers and for mixing the glued process-own wood fibers and the non-process fibers into a fiber mixture,
4. d. a feeding device leading into the dryer for feeding the un-sized non-process fibers into the dryer,
5. e. one of the feeder upstream separating device for separating compressed fiber bales, consisting of process-foreign fibers in largely isolated process foreign fibers with:
   • e ₁ . a tearing device for tearing the fiber bales,
   • e ₂ . a disruption device for breaking up the torn fiber bales to largely isolated process-external fibers,
6. f. Spreading device for spreading the fiber mixture into a fiber cake,
7. G. a hot press for pressing the fiber cake to a fiberboard of desired thickness.

From a conventional plant for producing a wood fiber board from process-own wood fibers and non-process fibers, the present system differs by the separation device and in that the feeder unbleached out of process fibers feeds a dryer and the dryer is designed to mix the glued process-own wood fibers and non-sized process foreign fibers ,

Optionally, a transfer device can be provided downstream of the disruption device for transferring the largely separated process-external fibers to the supply device. Such a separation device is per se, for example, from DE 10 153 175 A1 known.

Preferably, the dryer is formed with a pre-dryer and a after-dryer. In this way, an optimal moisture adaptation of the glued process-own wood fibers and the process-foreign fibers is achieved. A single stage dryer is also suitable in this regard, but it has been found that the higher temperatures of a single stage dryer are detrimental.

An exemplary embodiment of the invention will be explained below with the aid of a process scheme for producing a wood fiber board with process-inherent wood fibers and non-process fibers.

Provided roundwood 1 is first crushed in a chipper 2 to wood chips HS and washed in an adjoining cooker 3 and cooked. The thus prepared wood chips HS are then transferred to a refiner 4, in which they are digested to process own wood fibers HF. The process-inherent wood fibers HF produced in the refiner 4 are transported to a gluing device 5 and glued there. The gluing is done as wet gluing in a blowline 5. The glued process-own wood fibers HF are then transferred in a stream of air in a dryer 7 and dried in a pre-dryer 8. Unembellished process-foreign fibers FF are supplied in compressed fiber bales to the separating device 14 and fed to one or more feeding devices 15. In this case, the separating device 14 consists of an arbitrary multiplicity of separating units 14_1, 14_2,..., 14_n, wherein each separating unit consists of a feeding device 15, a subsequent tearing device 16 and a breaking-up device 17. In each separating unit 14_1, 14 2,..., 14_n, the fiber bales which have been discontinued there are separated into largely separated, process-independent fibers FF and subsequently transported further in a feed device 6 in an air stream. Such a separating device 14 is, for example, by the company Spezialmaschinen Dr. med. Otto Angleitner, 4600 Wels, Austria, sold under the name DOA-Fasermischanlage. The unwelded non-process fibers FF are fed to the dryer 7 via the feeder 6. The feeding device 6 closes between the pre-dryer 8 and the after-dryer 9 in the intake of the after-dryer 9. In the after-dryer 9, which likewise functions as a mixer, the process-inherent wood fibers HF and the non-process fibers FF are mixed in a stream of air to form a fiber mixture FG and optionally further dried. After passing through the after-dryer 9 or mixer, the fiber mixture FG is transported to a sifter 10, from which it then enters a spreader 11. About the spreader 11, the fiber mixture FG is scattered on a circulating conveyor not shown here in detail to a fiber cake. This fiber cake is passed over the conveyor belt through a pre-press 12 and then fed to the hot press 13, in which the fiber cake is pressed under high pressure and high temperature to a fiberboard of desired thickness. In this case, the adhesive melts on KL and combines wood fibers HF and process foreign fibers FF together.

Due to the fact that the glued process-own wood fibers HF are dried in the pre-dryer 8, when the non-process fibers FF are fed into the dryer 7, substantially no agglomerates are formed from process-rich wood fibers HF and unwelded non-process fibers FF which are no longer sizing at the time. In this way, during mixing, a particularly homogeneous fiber mixture FG is achieved, in which the glued process-own wood fibers HF and non-glued process-foreign fibers FF are largely isolated. A connection of the non-process fibers FF with a binder takes place only during pressing, during which the binder associated with the process-own wood fibers HF (glue) melts.

The DOA fiber blending plant theoretically allows any number of fiber bales of different types of wood and / or natural and artificial fiber materials to be given up and split in parallel and continuously, which are suitable for bonding with the adhesive KL. With one or more weighing devices WV not shown, the different fiber contents can be added as desired to achieve the desired product properties by an accurate mixing ratio. A substitution of high-quality raw and substitute materials with inexpensive fibers of cotton or fabric, plastics, annual plants, glass or rock wool is also possible with this method. If the board weight is to be reduced compared to a conventional wood fiber board, it is possible to use non-process fibers having a lower density than the process-own wood fibers used. If the bending strength is to be increased compared to a conventional wood fiber board, it is advisable, for example, to use glass fibers as process-external fibers.

In addition, a high degree of flexibility, due to the possibility of changing the type of fiber in the short term during ongoing production, is always available.

The feeding of particles, for example to increase the strength, to the process-own wood fibers HF, to the process-external fibers FF, to the fiber mixture FG or as a sole addition to the process-own wood fibers HF is likewise made possible. The air flow in the feeder 6 is particularly suitable in this regard.

LIST OF REFERENCE NUMBERS

1

spar

2

chipper

3

Stove

4

refiner

5

Gluing device / blow line

6

feeder

7

dryer

8th

pre-dryer

9

After-dryer / mixer

10

sifter

11

spreader

12

pre-press

13

hot press

14

separation device

14_1

first separation unit

14_2

second separation unit

14_n

last separation unit

15

feeder

16

ripping

17

digester

FF

process-foreign fibers

FG

fiber mixture

HF

wood fibers

HS

wood chips

KL

adhesive

WV

weighing device

Claims (10)

1. Process for the production of a wood-fibre board made of wood fibres intrinsic to the process and of fibres foreign to the process, with the following steps:

   a) defibration of wood chips (HS) in a refiner (4) to give wood fibres (HF) intrinsic to the process,

   b) transportation, into a gluing device (5), of the wood fibres (HF) intrinsic to the process, produced in the refiner (4),

   c) gluing, with an adhesive (KL), of the wood fibres (HF) intrinsic to the process,

   d) transportation, into a drier (7), of the glued wood fibres (HF) intrinsic to the process,

   e) introduction, into the drier (7), of the unglued fibres (FF) foreign to the process, where, before introduction, the unglued fibres (FF) foreign to the process are separated from pressed fibre bales,

   f) mixing of the wood fibres (HF) intrinsic to the process and of the fibres (FF) foreign to the process to give a fibre mixture (FG) in the drier (7),

   g) transportation of the fibre mixture (FG) into a scattering device (11),

   h) scattering of the fibre mixture (FG) to give a fibre cake,

   i) pressing of the fibre cake, in a hot press (13), to give a wood-fibre board of desired thickness.
2. Process according to Claim 1, characterized in that the unglued fibres (FF) foreign to the process are wood fibres.
3. Process according to Claims 1 and 2, characterized in that the proportion of the unglued fibres (FF) foreign to the process introduced, based on the fibre mixture (FG), is up to 20% by weight.
4. Process according to any of Claims 1 to 3, characterized in that the unglued fibres (FF) foreign to the process are introduced in an air stream.
5. Process according to one or more of the preceding claims, characterized in that the drier (7) comprises a predrier (8) and an afterdrier (9), and that the unglued fibres (FF) foreign to the process are introduced between the predrier (8) and the afterdrier (9).
6. Process according to Claim 5, characterized in that the wood fibres (HF) intrinsic to the process are dried in the predrier (8) before introduction of the fibres (FF) foreign to the process.
7. Process according to one or more of the preceding claims, characterized in that the mixing of the wood fibres (HF) intrinsic to the process and of the fibres (FF) foreign to the process takes place in an air stream.
8. Process according to one or more of the preceding claims, characterized in that the drying of the wood fibres (HF) intrinsic to the process takes place in an air stream.
9. System for the production of a wood-fibre board made of wood fibres intrinsic to the process and of fibres foreign to the process by a process according to at least one of the preceding claims with:

   a. a refiner (4) for the defibration of wood chips (HS) to give wood fibres (HF) intrinsic to the process,

   b. a gluing device (5) for the gluing of the wood fibres (HF) intrinsic to the process, produced in the refiner (4),

   c. a drier (7) for the drying at least of the glued wood fibres (HF) intrinsic to the process and for the mixing of the glued wood fibres (HF) intrinsic to the process and of the fibres (FF) foreign to the process to give a fibre mixture (FG),

   d. leading into the drier (7), a feed device (6) for the introduction of the unglued fibres (FF) foreign to the process into the drier (7),

   e. upstream of the feed device (6), a separation device (14) for the separation of pressed fibre bales consisting of fibres (FF) foreign to the process, to give substantially separate fibres (FF) foreign to the process, with:

   e₁. a breaker device (16) for the breaking of the bales,

   e₂. a defibration device (17) for the defibration of the broken bales to give substantially separate fibres (FF) foreign to the process,

   f. a scattering device (11) for the scattering of the fibre mixture (FG) to give a fibre cake,

   g. a hot press (13) for the pressing of the fibre cake to give a wood-fibre board of desired thickness.
10. System according to Claim 9, characterized in that the drier (7) is configured with a predrier (8) and an afterdrier (9).

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