EP1222061B1 - Device and method for disaggregating derived timber products - Google Patents

Abstract

The invention relates to a device for disaggregating pieces of derived timber products from cellulose and/or lignocellulose-containing products, especially particle boards, medium-density fiber boards and the like, with a transport device and at least one disaggregation container. The inventive device is also characterized in that the disaggregation container and the transport device are configured as at least one common densifier screw (1) with a housing-mounted outer shell and a driven shaft located therein. The shaft is provided with helices of a pre-defined pitch. The pieces of derived timber products are transported in the axial direction of the densifier screw (1) from a feed opening in the outer shell towards an outlet opening on the front side thereof in the axial direction (direction of transport). A feed opening (7) for vapor is provided in the outer shell between the inlet opening and the outlet opening.

Description

The present invention relates to a device for the digestion of wood-based materials according to the Preamble of the main claim as well as a procedure its implementation.

Such a generic device is known (US-A-3,741,863). A serves in this device trained as at least one stuffing screw Transport device for transporting the Digestion material, this one in a Outer jacket arranged discharge opening radially is transported. Furthermore, the feed opening the first stuffing auger as Inlet opening (77) used for steam. The disadvantage of this known device Need, besides the stuffing augers Seals in the form of a rotary valve (72) in front of the Provide feed opening of the first stuffing screw and in the form of a cyclone separator after the last one To provide a stuffing screw, creating such facilities are expensive.

It is also known (DE 198 19 988 A1), one as Conveyor screw designed transport device for Transport of the digestion material through the Use impregnation and pre-swell shaft while the second screw conveyor for transporting the digested material from the digestion shaft serves. In the actual digestion shaft, that is Digestion material not by screw conveyors transported. The device has the disadvantage that when digestion under pressure the filling shaft can be closed pressure-tight by suitable measures have to be. Also the discharge of the open-minded The material must be suitably pressure-tight.

The object of the present invention is a Generic device and a method create a continuous and therefore simple and economical digestion of Enable wood-based materials.

This task is solved by a generic Device and a generic method by the subject of the procedural or Device main claim.

It has surprisingly been found that a Arrangement of at least three Darning screws passing through one after the other Digestion material allows, the filling the seals at least three stuffing screws so far that the digestion process is also carried out under pressure can be. Steam is preferably below Overpressure, e.g. pressure of at least 2 bar above a between the feed opening and the discharge opening in the Outer jacket provided opening for the Steam is introduced into one of the stuffing augers that not the first or the last of the Darning screw arrangement is. It can in the pressure screw at the edge be observed up to atmospheric pressure can drop, but in the middle part Arrangement for maintaining a working pressure leads, which can be up to 11 bar overpressure, but at least 2 to 3 bar overpressure. At the Introduction of steam with an overpressure of 4 bar the digestion temperature is due to the Steam injection point at approx. 143 ° C. From spatial For reasons, an arrangement is preferred in which the Approx. Output of a stuffing screw at right angles in the entrance area of the following The screw feeder opens out.

A major advantage of the invention in one completely continuous process especially in that on elaborate Sealing measures on the device are dispensed with can still be a continuous one Work is possible. This is a work possible without opening and subsequent sealing of Parts of the plant, whereby neither energy nor pollutants can exit the system. The device can that is, both economically and ecologically Respect to be operated optimally.

In the method according to the invention, especially when using at least five Darning screws, digestion pressures from 2 to 11 bar Maintain overpressure, preferably in Range from 2 to 8 bar and especially in the range from 3 to 6 bar overpressure.

Because through the passage of the screw, the end to be unlocked Material is not only transported, but is homogenized at the same time by the Mechanical friction between the particles causes continuous crushing and the chemical hydrolysis facilitated. This will make the Digestion of the particles accelerates so that already a few minutes in the snails are sufficient, to get good information. at Wood materials that are more resistant to hydrolysis can Hydrolysis by appropriate measures, such as Increasing or lowering the pH value favors become.

The digestion process from the filling with the crushed chipboard fragments up to completely digested, moist wood mass is done with several, at least three in a row switched snails. This pressure tight Darning augers perform several functions: both the transportation as well as the continuous Crushing and hydrolysis of the pre-swollen Mass of wood on the one hand due to the friction of the particles to each other, and on the other hand the actual one takes place Digestion process by water, steam and Heat absorption within the pipe screw system. A modular construction is possible, whereby several identical screws and also drive systems can be used, making the cost crucial reduced.

Through the independently controllable Darning screws and drive systems can do that Feed rate to the given Process conditions are adjusted, the maximum limits only by dimensioning the Transport systems and the reaction speed of the Information is given.

Since the entire process is carried out under pressure, a pressure-tight system is required, which the Advantage has no harmful emissions the digestion process get into the environment can. Since the system is also operated without waste water environmental protection concerns in high Dimensions taken into account.

The first has proven to be useful Darning screw into which the material to be digested is introduced with preheated water fill. A water temperature of approx. 20 ° C to 95 ° C can be used.

The screw transport within the plant enables a homogenization of the wood mass and about the constant rubbing together during the Transports a good and continuous Size reduction, which is a good surface wetting causes. This can cause the enthalpy of the steam to over the entire pipe length can be fully used, because the rubbing against each other always Detach loosened layers mechanically and underneath expose lying, not yet solved layers that then easily caught by the steam. About The process can process higher process pressures again be accelerated.

The exhaust gas heat can be used almost completely and is compared to discontinuous operation not lost according to the state of the art. The heat the moist, open wood mass can can also be used by after leaving from the last screw conveyor shortest way into the dryer. Thereby heat loss and drying effort minimized.

With the help of the control of the feed speed can the water, steam and heat absorption of the Digestion material can be influenced very precisely what further optimization of the process parameters, especially the use of energy and optimal Litigation allowed.

According to the invention, stuffing snails are thus used, which make it possible during the Material transport a pressure in too build up transporting material. Such Snails, also known as stuffing snails are, for example, one-sided Snails, the outlet opening of which runs axially. she can be a progressive or degressive slope have, that is, the distances between the coils increase or decrease per turn.

A significant influence on the hydrolysis of the Wood-based materials have the digestion temperature. The higher the pressure of the steam used for the digestion the higher the digestion temperature. at a vapor pressure of 4 bar overpressure Temperature approx. 143 ° C. With digestion prints in the Depending on the order of magnitude of approx. 8 bar on the type of wood and other process parameters undesirable discoloration of the chips. The steam pressures used must be careful be monitored. Generally you become prints choose between 7 and 11 bar, but preferably from 2 up to 8 bar and in particular from approx. 3 to 6 bar Overpressure.

The transport speed through the stuffing augers is different, it can depend on the Vary the number of stuffing screws used. at a larger number of stuffing screws can Throughput speed can be increased at a smaller number, it must be reduced in order to dwell time necessary for the digestion guarantee. Depending on the pressure used the digestion can generally follow a Residence time approx. 30 min, preferably 20 min are completely effected so that when using more than three stuffing screws the dwell time per Darning screw is only a few minutes. Across from conventional discontinuous digestion processes this means a significant shortening of the Digestion time.

Under the conditions mentioned, in general The screw speeds reached in the On the order of a few revolutions per minute lie, for example 3 to 10 U / min.

It has proven to be advantageous when Material entry in the first stuffing screw add preheated water. The water temperatures can be 20 to 95 ° C. The water causes in Interaction with the abandoned wood materials an additional seal for the digestion overpressure used compared to Outside atmosphere.

The wood materials to be digested are before. Coarse pre-crushed digestion, where Particle sizes on the order of approx. 3 to 10 cm, preferably 3 to 5 cm as special have proven appropriate. A crushing under 2 cm is no longer advantageous because then the Separation of coatings or others Additions become more difficult.

It has been shown that under favorable conditions e.g. through a good seal of the individual Darning snails, already with three of the same ones are arranged one behind the other in the middle of which the pressure of the steam introduced appropriate digestion pressure can be maintained. With an arrangement of more than three stuffing screws becomes the zone of desirable reaction pressure still broadened, so the throughput speed the individual stuffing augers can be increased.

The first stuffing screw is advantageously turned on the feed side of the material with a high pressure lock equipped. On the exit side is one Pressure control is not absolutely necessary since here the pressure can drop to ambient pressure.

Further useful refinements of the invention are marked in the subclaims.

Figur 1

den Aufbau einer erfindungsgemäßen Vorrichtung mit insgesamt fünf Stopfschnecken zur Durchführung des erfinderischen Verfahrens.

The invention is explained in more detail below with the aid of the following description with reference to the drawing and the examples. The drawing shows:

Figure 1

the construction of a device according to the invention with a total of five stuffing screws for performing the inventive method.

EXAMPLE 1

Five stuffing snails were made in a row arranged that the axial exit each Darning auger sideways approximately at right angles Entrance area of the following auger einmündete. All connections between the Plug screws were designed to be pressure-tight.

The stuffing snails all had one 400 mm in diameter and 2.5 m in length. The It was driven by an electric motor uniform power of 10 kW. The first Darning screw was with a high pressure lock Fill level indicator provided.

In the middle of the third snail was one Steam supply line arranged with a steam source for saturated steam of 5 bar abs. was connected. The last snail had one Vapor suction device at the end of the screw.

Chipboard material which had been comminuted to a particle size of approximately 8x8x20 cm ^{3 was introduced} into the first stuffing screw. The screw was filled with preheated water, which had a temperature of approx. 90 ° C.

The feed speed of the stuffing augers was like this controlled that a dwell time of approx. 5 min. resulted in each stuffing screw. In the steam supply line the third stuffing screw became saturated steam with a Pressure of 4 bar overpressure metered in.

Those at the exit of the last snail Chips corresponded both visually and in the Particle size largely customary fresh chips.

The device shown in Figure 1 contains five in a row arranged augers 1, 2, 3, 4 and 5, which are driven by drive motors 6. The The axial exit area of each screw is axial Direction perpendicular to the entrance area of the flanged subsequent stuffing screw, whereby pressure-tight connections are used. The Darning screw 3 contains a steam supply 7, the is connected to a saturated steam source (not shown). The stuffing screw 1 contains a feed device 8 for entering the digestion material. At the The end of the last screw 5 is either one Vapor suction device or a spring cover 9 arranged.

The device shown in Fig. 1 has overall five pressure or so-called stuffing screws 1, 2, 3, 4, 5, each by drive motors 6 are driven. At the first snail the supply of those that have preferably already broken Wood material pieces as material feed. At the last snail 5 is an end Dispensing opening provided with a spring cover. The five stuffing screws are arranged one behind the other and serve both as a digestion container and as Transport device for the wood-based material pieces. Each stuffing screw has a housing-fixed Outer jacket 10 and an arranged therein drivable shaft 11 arranged around it Coils 12 of a predeterminable slope. Between the gears of the spirals on the one hand and between the (inner) shaft and the (outer) outer jacket the particles are transported. The stuffing snails 2, 3, 4, and 5 indicate when reproduced Embodiment the same, each other but possibly different slopes of the Spirals up.

In contrast, the stuffing screw 1 has coils 13 changing diameter or pitch.

The pressure screw and the stuffing screw 3 are each arranged horizontally. The On the other hand, stuffing screws 2 and 4 are angled, preferably arranged vertically.

The individual stuffing augers are like this connected in series that the Wood material pieces in the axial direction (Transport direction) 14 of the stuffing screw from the Feed opening 15 in the outer jacket 10 to one frontal discharge opening 16 in the axial direction are transported, being between the Feed opening and the discharge opening in the outer jacket 10 in the stuffing screw 3, the inlet opening 7 for Steam is provided. The stuffing screw 2 can with an inlet opening 17 for water, preferably Be equipped with hot water. All stuffing snails, or at least part of it can be heated be designed.

Claims (13)

1. Device for disaggregating derived timber products consisting of cellulose-containing and/or lignocellulose-containing materials, in particular, chipboard, medium-density fibreboard and similar, with a transport device and at least one disaggregating container, wherein the disaggregating container and the transport device form at least one combined packing screw (1,2,3,4,5) with a rigidly-mounted exterior casing (10) providing a driveable shaft (11), on which spirals (12) of a predetermined gradient are mounted, and wherein the derived timber products are transported inside the packing screw (1,2,3,4,5) in the axial direction (transport direction 14) from a supply opening (15) in the exterior casing (10) to an output opening (16),
   characterised in that
   the output opening (16) is arranged at an end face; that only one inlet opening (7) for steam is provided in the exterior casing (10) of the combined packing screw between the supply opening (15) and the output opening (16);
   that three or more packing screws (1,2,3,4,5) are provided;
   that the only one steam inlet opening (7) is provided in one of the packing screws (5) between the first or last packing screw (1 or 5 respectively) in the transport direction (14);
   and that the several packing screws (1,2,3,4,5) are each arranged at right angles to one another in their axial orientation.
2. Device according to claim 1,
   characterised in that
   the inlet opening (7) is designed as a steam pressure opening.
3. Device according to claim 1 or 2,
   characterised in that
   the outlet opening (16) of the last packing screw (5) in the transport direction (14) is provided with a vapour extraction device or a spring-loaded shutter.
4. Device according to any one of claims 1 to 3,
   characterised in that
   a total of five packing screws (1,2,3,4,5) arranged one after the other are provided.
5. Device according to any one of claims 1 to 4,
   characterised in that
   some of the packing screws (1,2,3,4,5) are arranged to run horizontally and some to run vertically in the transport direction (14).
6. Device according to any one of claims 1 to 5,
   characterised in that
   at least one of the packing screws (1,2,3,4,5) is designed to be heated; and/or that the gradient of the spiral (12) in at least one of the packing screws is not constant but increases or decreases in the transport direction (14).
7. Method for the disaggregating derived timber products made from lignocellulose-containing material, in particular, chipboard, medium-density fibreboard and other residual and waste products made from lignocellulose-containing materials, using a device according to claim 1, wherein the derived timber products are continuously transported through the end-face output openings (16) of at least three pressure-tight packing screws (1,2,3,4,5) arranged one after the other, being subjected, in this context, to the shear forces and frictional forces occurring in the packing screws, and wherein steam is injected under pressure into at least one of the packing screws (1,2,3,4,5), which is not the first or the last of the packing screws.
8. Method according to claim 7,
   characterised in that
   the steam is injected with a positive pressure of at least 2 bar.
9. Method according to claim 7 or 8,
   characterised in that
   with an arrangement of an odd number of transporting packing screws (1,2,3,4,5), the steam is injected into the middle one of the same.
10. Method according to claim 7 or 8,
    characterised in that
    with an arrangement of an even number of transporting packing screws (1,2,3,4,5), the steam is injected into one of the middle packing screws.
11. Method according to any one of claims 7 to 10,
    characterised in that
    the steam provides a positive pressure from 2 to 11 bar.
12. Method according to any one of the preceding claims, characterised in that,
    before disaggregation, the derived timber products are shredded to a particle size of at least 5x5 cm.
13. Method according to any one of the preceding claims,
    characterised in that
    the packing screws are additionally heated.

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