EP2213431A2 - Method for operating an assembly for producing fibre, MDF, HDF, wood or plastic boards from fibres or fibrous material - Google Patents

Abstract

The method involves transporting fibers over a transporting section (22) by a blow line (2) with high speed. Binding agents are applied into the blow line by nozzles, where the blow line has different characteristics along the length, and the agents includes adhesive liquors and additives. Characteristics of parts of the section are changed for adapting the section to different flow rates of the fibers or for maintenance purposes by a deflector (4) provided between two blow lines (2, 9), and one of the blow lines is exchanged with the other blow line. An independent claim is also included for a system for manufacturing a wooden board, plastic board and fiberboard comprising blow lines for transporting fibers.

Description

The invention relates to a method for operating a system for producing fiber, MDF, HDF, wood-based or plastic plates from fibers or fiber-like material according to the preamble of claim 1. The invention further relates to a system according to the preamble of claim 8.

The production of material plates from medium-density fibers or similar materials are now automated processes and have been used in many countries for years. As is known, the compression of processed chips or fibers takes place either clock-bound or continuously. In addition to the many plant components before and after the press, the production of a spreading material mat by means of spreading machines plays an outstanding role, since the quality of the produced spreading material mat is an important factor in addition to the quality of the raw materials. In the large-scale industrial production of wood-based panels come continuously working presses, but partly still single or multi-day presses, for use. The urge to produce cost-effective material plates from natural raw materials and artificially produced binders forces producers to develop more and more efficient processes. Special emphasis is placed on energy costs, raw material and binder savings with consistent quality and technically optimized plant construction with minimal downtime and low wear. Basically, the term binder is understood to mean a so-called adhesive liquor which consists of an adhesive in its main component. Depending on requirements, in addition emulsion, hardener, formaldehyde scavengers, dyes, insect repellent and antifungal agents and other additives are added. It is also common to use the adhesive without additives. Suitable binders are not exhaustive: isocyanates (Mdl), melamine urea formaldehyde (MUF), urea formaldehyde (UF), MUPF or PF.

The chips are usually already delivered as chips or produced on site and fed to the gluing before or after drying. Fibers are produced by Zerfaservorrichtung on site and conveyed after the defibration between two grinding discs through a transport tube (English: Blow Line) to a dryer. In a pulping of the fibers by means of a steam cooker, the excess steam is used to drive the fibers through the transport tube. Depending on the size and structure of the system, the transport tube may have a length of up to 100m. During the Transport, which is preferably carried out at supersonic speed in a relatively small tube of small inner diameter, the fibers are glued and then conveyed into a dryer. This high-pressure gluing poses great challenges in a transport tube, since the flow is extremely turbulent, with a Reynolds number of 7 × 10 ⁵ to 3 × 10 ⁶ . The speed of the fibers is in a range of at least 50 m / s up to a speed of 474 m / s. Subsequently, the chips or fibers are usually dried, stored in bunkers and metered scattered on a base and pressed by pressing to sheets of material.

The necessary binder for gluing was previously introduced with nozzles in the transport tube, which dissolve the binder such that it is preferably injected with a size in the multi-digit micron range. With so-called atomizing (pressure) spray nozzles, it is possible to split the binder to an approximate size of 100 to 40 microns. But it is necessary to work with high-pressure nozzles, which dissolve the binder on the nozzle head by relaxing in another pressure range. Recent research and developments have shown new ways of injection possibilities, whereby either the binder at the outlet or already within the nozzle is dissolved by means of steam into very small particles. It is possible to increase the above-mentioned 40 micron droplet size of the binder by up to 20 microns below. For optimum distribution of the binder in a turbulent high-velocity flow of fibers, the smallest dissolution of the binder is urgently preferred.

In fiberboard production, during or after the gluing, the fiber material is transferred to a dryer, in the presently preferred embodiment a tube dryer, and dried. To separate the dryer air from the dried fiber material usually a cyclone is used, the polluted air dryer are cleaned as exhaust gases depending on the need or environmental conditions in a pre-filter and then usually burned. The method used is well known and is implemented in devices namely "RTO = Regenerative Thermal Oxidizer". The dried fiber material is stored after the cyclone in bunkers and discharged as needed in a scattering station, which forms the fiber material to a spreading material on a continuously moving forming belt and transported in the direction of a press. Usually after a pre-pressing or pretreatment of the spreading material mat, it is transferred to a continuously operating press and pressed by means of pressure and heat to form a material plate. After pressing, the surface grinding of the surfaces and the fabrication into specified sizes are carried out with subsequent stacking.

Fiber manufacturing facilities today are grateful for small orders to ensure that production is fully utilized in a 24/7 rhythm. Accordingly, it is no longer usual to drive the same type of product over several hours or even days, but the production thickness and / or the production density of the material plates to be produced are changed several times a day. This means that the throughputs of fibers in the transport tube are regularly adjusted to the required amount of glued material.

Until the time of the raw materials crisis, it was irrelevant whether the gluing in a transport tube was carried out effectively and with a minimum of raw materials, especially in the case of rare small margins. As described, this circumstance has changed significantly and plant operators want optimum and, above all, economical gluing for all types of throughput quantities. So far, the optimization of the gluing was controlled by the pressure of the injecting binder, much material throughput corresponds to high pressure and low material throughput rather lower pressure. This is also due to the fact that the spray cone of the binder on the inner diameter touched opposite and bakes the binder there and coagulated to glue lumps. However, these solutions have proved to be very wear-resistant for the nozzles and also do not lead to optimal results, especially with changing material throughputs. Other solutions for binder savings and optimized application of the Binders to the moving fibers in a transport tube can be found, for example, in: DE 16 32 450 A1 ; with an apparatus for continuously mixing relatively small quantities of a finely divided component with a carrier moved by an air flow. In this publication, no steam is used in the transport tube and is more suitable only for very small flow rates. The solution proposed here is to flexibly design the transport tube in parts and, if necessary, to work with impact agents so that no caking forms. Also, a rotation of the transport tube or the permanent splitting of the transport tube to several transport tubes is proposed simultaneously. Here, only static solutions are used and an adaptation to the throughput is not provided.
DE 195 06 353 A1 shows a method and apparatus for wetting with a fluid that tries to improve the Beleimergebnis over a targeted cross-sectional change of the transport tube in the region of the injection. In this case, a reduced diameter of the transport tube is preferably used in front of the nozzles in order to increase the turbulence in the mixing zone. The adaptation to different flow rates is made possible through the nozzle design, but has not proven optimal in practice.
The research and teaching in the following years to date has shown that the transport tubes are structurally designed in their design and are designed based on calculations to an average case. Mostly other throughputs are not considered significantly or attempts are made through other means and ways to compensate for them.
DE 102 26 820 B3 describes a transport tube with several turns, which is applied by the deflection of the fiber flow on one side of the transport tube and is sprayed from the opposite side. DE 100 59 881 A1 shows a plant for fiber processing, in which the Beleimzone has a double tube, wherein the inner perforated tube is externally supplied with compressed air to prevent sticking of the fibers to the inner tube wall.
DE 102 47 412 A1 also shows a cross-sectional change before gluing, wherein additionally by a splitting plate, the fibers are positioned in the direction of Beleimdüsen before they fall in a chute down.

From practice it is known to compensate for lower flow rates of material in a transport tube with higher steam input. For this purpose, additional steam lines are attached at suitable points of the transport tube, which are acted upon at small flow rates with additional steam. About the shredder or the steamer itself is an increase in the amount of steam only limited possible because an increased withdrawal of steam again affects the cooking time and the pressure in the steam cooker. Also these possibilities are no more in today's times economically feasible, since the energy costs per unit of time are not profitable and corresponding environmental incompatibilities go hand in hand.
The invention is therefore an object of the invention to provide a method for operating a system and a system with which optimal gluing the fibers at different throughputs per unit time can be achieved and at the same time the gluing of the fibers with binder meets high standards. In this case, further procedures and a system are to be created, through which an adjustment during production breaks during operation should be possible.

The solution for the method for operating a system is that to adapt to different throughput quantities of the fibers or for maintenance purposes, at least a part of the transport path is changed in its properties, the change being made such that by means of at least one switch between at least two transport tubes is switched over and / or at least a part of the transport tube is replaced with at least a second transport tube.

The solution for a system according to the invention is that to change the properties of the transport path at least part of the transport path consists of at least two transport tubes, wherein for the alternating control of these transport tubes at least one switch (4) and / or at least one flange in the transport path is arranged.

With regard to the term, the invention under the properties of the transport tube, the embodiment of a transport tube, which must not always be designed to be constant in terms of its inner diameter. From the prior art examples, a variety of geometrical variations are known for the inner diameter of such a transport tube. The teaching of the invention states that in the case of maintenance and / or in a production change, the transport tube can be adapted with its properties to the respective production. For this purpose, the possibilities described below are conceivable. The system alone can be operated and has advantageous features, but of course is also particularly suitable for carrying out the method. The term transport line stands for the transporting of fibers in a plant for the production of fiberboard, preferably by a defibrator (steam cooker) or a fiberizer of the transport is started and is preferably introduced into a tube dryer. Preferably, the fibers or the fiber-like material are glued in the transport path.

Advantageously, the invention solves a difficult problem for the plant operator. Because of the invention, plant operators are now able to easily accept small orders or marginal contracts, which work with their requirements on the edge of the admissibility of the production plant and thus challenge a higher consumption of raw materials. Due to the simple and inexpensive solution, which is also easy as Retrofit solution can be offered on the market, a conventional system at least a part or an entire transport pipe, in the embodiment of the fiberizer to the pipe dryer, extended. Thus, it is possible, adapted to the throughput of fibers per unit time, each to select the most suitable for this throughput transport pipe and integrate it into the production plant. By experiments, calculations or models, the operator learns which inner tube diameter or the geometry of the transport tube is best suited for the just upcoming purposes and will even select this automatically if necessary. Primarily, calculations related to the steam consumption of the fiberizer (refiner) and the fiber flow rate in conjunction with the inside diameter are performed. Of course, this production part can also be continuously monitored with measuring devices (speedometer in the transport tube, glue consumption of the binder nozzles, etc.) and with persistent poor measurement results, the operator or the operator can automatically be informed that a change between the transport tubes seems reasonable or necessary.
In the field of maintenance, it is advantageous to arrange the parts of the transport tube interchangeable, which regularly (could) contaminate and must be cleaned accordingly. Also, a visit of a tube several meters long on wear or caking indoors is not feasible within a few minutes, but needed Staff and equipment. The changeover between the transport tubes can be carried out manually, by replacing the connections of two fixed long transport tubes (up to 100 m), or a part of the transport tube is replaced and coupled with suitable sealable flanges. In more complex embodiments, the switchover can be performed by means of switches, preferably also during production.

It should be noted here that the switching between two transport tubes, or parts thereof, is in the foreground, wherein the transport tubes, which are exchanged, according to the application may also have different inner and / or outer geometries over their length to the gluing to optimize. It is also the application of the same transport tubes conceivable, if at certain points on the system increased wear or caking occur that must be regularly checked, monitored and / or cleaned

Further advantageous measures and embodiments of the subject matter of the invention will become apparent from the dependent claims and the following description with the drawing.

Figur 1

Eine Übersicht einer stark vereinfachten Plattenherstellungsanlage,

Figur 2

einen schematischen Schnitt durch die erfindungsgemäße Anordnung zweier mittels zweier Weichen umschaltbarer Transportrohre mit unterschiedlichem Innendurchmesser,

Figur 3

eine Anordnung nach Figur 2 mit nur einer Weiche und zwei direkten Zugängen der unterschiedlichen Transportrohre in den Rohrtrockner,

Figur 4

einen schematischen Schnitt durch die erfindungsgemäße Anordnung zweier mittels Flansche austauschbarer Transportrohre mit unterschiedlichem Innendurchmesser,

Figur 5

ein weiteres Ausführungsbeispiel mit einem Zerfaserer, der zumindest zwei unterschiedlich steuerbare Ausgänge in zwei unterschiedliche Transportrohre aufweist und

Figur 6

ein weiteres Ausführungsbeispiel nach Figur 4 mit einer Anordnung der Beleimdüsen außerhalb des austauschbaren Bereichs des Transportrohres.

Show it:

FIG. 1

An overview of a greatly simplified plate manufacturing plant,

FIG. 2

2 shows a schematic section through the arrangement according to the invention of two transport tubes with different inner diameters that can be switched over by means of two switches,

FIG. 3

an arrangement after FIG. 2 with only one switch and two direct entrances of the different transport tubes into the tube dryer,

FIG. 4

FIG. 2 shows a schematic section through the arrangement according to the invention of two flanges exchangeable transport tubes with different inner diameters, FIG.

FIG. 5

a further embodiment with a shredder, which has at least two different controllable outputs in two different transport tubes and

FIG. 6

a further embodiment according to FIG. 4 with an arrangement of Beleimdüsen outside the exchangeable portion of the transport tube.

To FIG. 1 begins the exemplary and simplified illustrated manufacturing process with a defibrator 1, also called shredder, which produces by thermomechanical defibration of wood, wood waste or similar starting material by means of pressure and steam fiber or fibers 20. These fibers 20 are a transport line 22 a transport tube 2, (technical term in the industry or for the skilled person: "blow-line") passed, and during transport with one or more Beleimdüsen (in FIG. 1 not shown) glued. Subsequently, the Fibers 20 introduced at a higher speed than the prevailing air velocity of the dryer air 6 in a tube dryer 3. The necessary for the transport air velocity of the dryer air 6 in the tube dryer 3 is generated by a fan 12, which is supplied with heated (about 180 ° C to 220 ° C) and preferably dry air. After the tube dryer 3, which can be up to 100 m long, the dried fibers are transferred to a cyclone 14, which separates the dryer air 6 from the fibers 20 and transfers the dryer air 6, possibly with a certain amount of dust, to a pre-filter 16. Subsequently, the dryer air 6 is post-treated in a thermal exhaust air purification 17 and discharged to the environment. The dried fibers are transferred in the cyclone 14 via a rotary feeder 15 to a fiber bunker 8 and controlled from there discharged into a spreader 10, which scatters a grit mat from the glued and dried fibers 20 on a forming belt 7. Subsequently, the spreading material mat is introduced into a continuously or discontinuously operating press 11 and, after being pressed into a fiber plate, transferred to the region of the post-processing 18. In post-processing, the fiberboard is assembled, sanded and stored accordingly.

If now only medium-density fiberboard or even lightweight fiberboard produced according to high-density fiberboard, the current process requires a total of less fiber material and the defibrator 1 are less Fibers 20 discharged into the transport tube 2. Experience has shown that the previous systems work optimally only in a certain area and are usually only sub-optimal with regard to gluing for less frequented work areas. In order to be able to optimally adjust these areas as well, in particular with regard to the conveying speed and the gluing quality, they are becoming less important FIG. 2 switched the switches 4 and no longer the first transport tube 2 continuously applied with fibers 20, but the second transport tube 9, which also has nozzles 5 for gluing, activated. It is understood by those skilled in the art that not only two different transport tubes 2, 9 can apply, but a variety thereof, depending on the application. There are even combination systems conceivable that use in addition to fibers or fiber-like material and Kunststoffzumischungen or other substitutes and this need special transport tubes for gluing. In a particularly preferred case, there are three different transport tubes for low fiber throughput, medium (normal) fiber throughput, and high fiber throughput. With lower fiber throughput, less vapor is transferred from the defibrator 1 in the transport path 22. Already here is recognizable that with low fiber throughput per unit time a narrower transport tube is useful than at high fiber throughput, as a tight transport tube can clog and makes a meaningful gluing impossible. At the same time with a large amount of fibers per unit time too large a transport tube of disadvantage, because too little Steam the necessary transport speed for optimum gluing is not achieved. As described, the supply of steam to the transfer tube is an undesirable alternative given the environmental issues and high energy costs. A person skilled in the art can simulate the invention in this context with the choice of words smaller and larger since, in addition to the size of the transport tube, the desired transport speed and the type of material represent criteria which require detailed calculations which are within the scope of a plant manufacturer.

Basically, the subsequent part of the process is its usual course and the fibers 20 are transferred after gluing over the remainder of the first transport tube 2 in the tube dryer 3 and transferred with at least one outlet nozzle 19 to the dryer air 6 in the tube dryer 3.

To FIG. 3 this process is modified insofar as that after the first switch 4 no further switch is present and the two transport tubes 2 and 9 have two separate outlet nozzle 19 in the tube dryer for transferring the fibers 20 to the dryer air 6. Again, two sets of nozzles 5 are necessary for this embodiment, since the nozzles 5 are configured separately for the corresponding transport tube 2 or 9. In the FIGS. 2 and 3 is also a starting pipe 13 can be seen. This tube is used to sort out poor or insufficient fibers during startup and one To prevent their entry into the production process. The present development does not understand such a start-up transport tube as a transport tube according to the invention, since it does not open into a tube dryer 3 or serves to weed out fiber material from the process.

FIG. 4 shows a simple solution to the problem of the invention, particularly helpful for retrofitting or tight space. If necessary, the second transport tube 9 is inserted into the transport tube 2 and has other properties, for example a different inner diameter, at least in parts than the substituted part of the transport tube 2. A flanged solution with flanges 21 is basically no problem due to the small outer diameter of the transport tubes , The coupling and sealing of the flanges 21 of the transport tubes 2, 9 can also be carried out automatically, if there is a need or desire for it. On a graphic solution of such standard components has been omitted. The person skilled in the art will take the necessary measures to reliably produce such compounds according to the state of the art and according to the technical rules.

In another alternative solution after FIG. 5 has the system or the defibrator 1 directly to three outputs, which can be switched between these outputs as needed. Again, a starting pipe 13 is introduced.

In order to optimize the number of nozzles 5 in the system, it is further recommended to arrange them in a first region of the transport tube 2. In the direction of production, a part of the first transport tube 2 is then replaced by the transport tube 9 only as needed.
It is understandable to the viewer that in the context of the invention, further possibilities are conceivable in order to enable the inventive replacement of parts or the entire transport tube 2 of the transport path 22 or to make it as cost-effective.

With regard to the nozzles which can be used, it should be noted that the system described or the method is extremely well suited for gluing nozzles which disperse the binder with steam before entering the transport tube and / or that the binder is comminuted with steam as it exits the nozzle Insert transport tube. In both nozzles, steam is used to split the binder in the range of less than 40 microns and thus to allow optimum injection of the fibers when injected into the transport tube. These nozzles are particularly suitable because in the dispersion of the vapor with the binder in a mixing chamber in front of the nozzle itself or before entering the blowline, the dispersion can be optimally pressure-controlled, but in the transport tube a certain minimum speed of the fibers or the Steam needed. If this minimum speed is not reached, the gluing quality also drops again and steam must be supplied. Both shredding nozzles, the binder is comminuted with laterally arriving steam bursts shortly or during the entry of the binder into the transport tube and introduced into the transport tube. The small amount of steam additionally introduced here is marginal and only necessary for dissolving or mixing the binder.

List of Reference Numerals: DP1369EP

1.

defibrator

Second

first transport pipe

Third

tube dryer

4th

switch

5th

jet

6th

dry air

7th

forming belt

8th.

fiber bunker

9th

second transport pipe

10th

spreader

11th

Press

12th

Fan

13th

Anfahrrohr

14th

cyclone

15th

rotary

16th

prefilter

17th

exhaust air cleaning

18th

post processing

19th

exhaust nozzle

20th

fibers

21st

flange

22nd

transport distance

Claims (10)

Method for operating a plant for producing fiber, MDF, HDF, wood-based or plastic plates from fibers (20) or fiber-like material in which fibers (20) are transported at high speed over a transport path (22) through a transport tube (2) be and in the transport tube (2) by means of nozzles (5) with a binder consisting of an adhesive liquor with / without additives, are acted upon, wherein the transport tube (2) of the transport path (22) in its length may have different properties, characterized characterized in that in order to adapt to different throughput quantities of the fibers (20) or for maintenance purposes at least a part of the transport path (22) is changed in its properties, wherein the change is made such that by means of at least one switch (4) between at least two transport tubes ( 2, 9) is switched and / or at least a part of the transport tube (2) with at least a second n transport pipe (9) is replaced. A method according to claim 1, characterized in that the two transport tubes (2, 9) have different properties. A method according to claim 1 or 2, characterized in that the gluing is performed before and / or in the part of the transport path (22) which is changed for different flow rates or for maintenance purposes. Method according to one or more of claims 1 to 3, characterized in that for small throughput amounts of fibers compared to a large transport pipe for large throughputs smaller transport pipe is used. Method according to one or more of claims 1 to 5, characterized in that for gluing the binder is dispersed before entering the transport tube with steam and / or that the binder is crushed when exiting the nozzle with steam introduced into the transport tube. Method according to one or more of claims 1 to 5, characterized in that the transport path (22) is changed by the nozzles (5) in the transport direction at least to one meter in length. Method according to one or more of claims 1 to 6, characterized in that the exchange and the release or locking of the connection of the transport tubes (2, 9) by means of automatic actuators takes place. Plant for the production of fiber, MDF, HDF, wood-based or plastic plates from fibers or fiber-like material in which fibers are transported at high speed through a transport tube and in the transport tube with a binder consisting of an adhesive liquor with / without aggregates, be acted upon, characterized in that for changing the properties of the transport path (22) at least a portion of the transport path (22) consists of at least two transport tubes (2, 9), wherein for the alternating control of these transport tubes (2, 9) at least one switch ( 4) and / or at least one flange (21) in the transport path (22) is arranged. Installation according to claim 8, characterized in that for introducing the binder into the transport tube, the binder with vapor-dispersing nozzles (5) and / or that the binder at Outlet from the nozzle with steam-pulverizing nozzles (5) are arranged. Installation according to claim 8 or 9, characterized in that for the exchange and for locking and unlocking the connection of the transport tubes (2, 9) are arranged automatic actuators.

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