METHOD AND PLANT FOR MANUFACTURING BLOCKS

Description

[0001] The invention relates to a method and a plant for producing blocks, in particular pallet blocks, having the features in the preamble of the main claim.

[0002] Such a system for producing blocks with an extrusion press and air dryer is known from EP 1 925 413 A2. The air dryer is designed as a single-layer dryer and has up to four parallel and mutually separated drying lines, each comprising a single conveyor belt for the material to be dried and a plurality of chambers arranged thereon with their own drying air flow. Each chamber contains a blower and a suction duct connected between the upper and lower strands of the conveyor belt.

[0003] EP 2 425 947 A2 also discloses a system for producing blocks according to the prior art.

[0004] DE 40 22 702 C1 discloses a method and system for drying loose and free-flowing wood drying materials using warm drying air. The exhaust gas from the drying air discharged through the chimney is intended to have a low pollutant load and be free of resin or wood tar components. The warm drying air is directed from below through two stacked belt conveyors with layers of drying material in a large drying chamber and extracted in the upper chamber area. The upper belt conveyor and the upper layer of drying material serve as filters for the pollutant-laden drying air. Furthermore, unpolluted drying air is directed outside the belt conveyors for extraction to reduce the pollutant concentration.

[0005] The object of the present invention is to demonstrate a better manufacturing technique for blocks.

[0006] The invention solves this problem with the features in the main claim.

[0007] The claimed manufacturing technology, i.e. the plant and the associated process, have various advantages.

[0008] Thanks to improved drying technology, a low residual moisture content of, for example, 2 to 4% dry matter can be achieved for the dried chip material at the dryer outlet, which is advantageous for extrusion processing. Under certain circumstances, the residual moisture can be as low as 6% dry matter.

[0009] The multi-layer continuous air dryer allows for optimal utilization of the thermal energy contained in the heated dry air stream and improved handling of the moisture absorbed in the dry air stream after passing through the chip layers. The sequential flow through several chip layers of varying moisture content is advantageous for this purpose.

[0010] Flowing first through a relatively dry layer of chips and then through a layer of chips with a higher moisture content allows the dry air to gradually increase its moisture content along its path. This is beneficial for the drying effect. The low moisture content or released water from the relatively dry layer of chips can be absorbed particularly well by the hot dry air stream. The resulting slightly moistened and slightly cooled dry air stream, on the other hand, is beneficial for the gradual drying of the following, relatively wet layer of chips.

[0011] The multiple chip layers can be arranged one above the other and / or next to each other. A stacked arrangement is advantageous so that the air can flow directly through the chip layers of varying moisture levels one after the other. A substantially vertical and continuous orientation of the dry air flow is beneficial for the drying effect. Flow losses can be kept to a minimum. Furthermore, a switchable bypass can be more easily implemented on the multi-layer continuous dryer, which allows for direct air flow to the subsequent, particularly relatively wet, chip layer as needed. This occurs, for example, when the temperature of the subsequent chip layer is too low.

[0012] The chip material is transported through the multi-layer continuous dryer, with the wet chip material entering at an inlet and the dried chip material exiting at an outlet after passing through. Between the separated chip layers, the chip material can preferably be transferred vertically. Within the chip layers, the chip material can also be moved during the dryer. This preferably involves a circular movement, e.g., a circular rotational movement around a central and preferably upright axis of rotation. The continuous movement of the chip material can be directed countercurrently to the flow direction of the drying air stream.

[0013] The multi-layer continuous dryer can be designed and configured so that the chip layers are exposed to a uniformly conditioned dry air stream as they pass through. The dry air stream can thus have the same temperature throughout the entire passage and exposure area. This facilitates and simplifies the heating of the dry air stream. This can be fed by ambient air. Alternatively or additionally, the dry air stream can be recirculated and possibly regenerated or treated, particularly dehumidified.

[0014] The chip layers of varying moisture levels can each be arranged on a movable and air-permeable chip carrier through which the drying air stream passes. The movable chip carriers transport the chip through the multi-layer continuous dryer. The chip carriers can be designed in various ways, e.g., as belts, discs, or rings. Disc- or ring-shaped chip carriers can rotate around a central and preferably upright axis of rotation. The chip carriers can be arranged separately from one another, particularly when arranged one above the other. A transfer device for the chip can be arranged between the separate chip carriers.

[0015] For the drying effect, it is beneficial if the chip carriers and chip layers, through which the dry air stream passes one after the other, are moved in opposite directions during the drying process. This results in opposing drying progress for the chip layers at the points where the dry air stream passes one after the other. As the drying process progresses, the moisture content decreases and the temperature rises locally in the chip layer.

[0016] The relative humidity values of the successively flowed through chip layers add up. Across the entire layer, the dry air exiting after the last chip layer has essentially the same humidity value, or water content, throughout. The dry air stream absorbs essentially the same amount of water and moisture at each of these successively flowed through chip layers. Furthermore, the opposing drying progress at these successively flowed through points results in essentially constant heat release from the dry air stream. The relatively dry chip layer flowed through first has a higher temperature than the relatively wet chip layer flowed through next.

[0017] The number of chip layers and chip carriers arranged side by side and / or one above the other, and through which the flow passes one after the other, can vary. The number of layers and carriers can be two, for example. Alternatively, it can be higher, for example, three or more.

[0018] The multi-layer continuous dryer can have a heating device and a circulation device for the dry air stream. These can be designed in different ways. The heating device can be designed, for example, as a heat exchanger, with the primary energy coming from the waste heat of a combined heat and power plant or from a burner or similar device. The dry air stream can also be heated in other ways, e.g., by direct firing.

[0019] The circulation system can move the dry air stream from an inlet point to an outlet point and, if necessary, additionally or alternatively, in a circuit. The circulation system is equipped with suitable fans or similar devices. It can also include a device for heat recovery and / or dehumidification of the dry air stream.

[0020] In addition to the air dryer, the drying system can comprise one or more additional dryers. This can be, for example, a mechanical dryer, particularly a crusher. The mechanical dryer can be installed upstream of the air dryer. Upstream mechanical dehumidification can reduce the energy consumption of the air dryer or multi-layer continuous dryer. The desired residual moisture content in the dried chip material can be achieved with potentially reduced effort.

[0021] A particle former can be installed upstream and / or downstream of the drying device. This changes, in particular reduces, the particle size of the chip material and can preferably also adjust it to a desired size. A particle former can be designed in any suitable manner, e.g., as a hammer mill.

[0022] Drying can be simplified and improved with a particle former installed upstream of the drying device, particularly the air dryer or multi-layer continuous dryer. By changing, particularly reducing, the particle size, the total particle surface available for drying can be increased. This facilitates drying of the chip material and achieves the desired low residual moisture content after air drying. A particle former can be installed upstream and / or downstream of a mechanical dryer in the drying device. A particle former can also be combined with a mechanical dryer to form a single structural and functional unit.

[0023] A particle shaper downstream of the drying device enables the particle size to be changed, particularly reduced, to the desired level for subsequent extrusion. The particle size can also be stored before the subsequent extrusion. Classification of the dried particle size is unnecessary. This can be done alternatively, if necessary, before storage.

[0024] One or more feeders for the dried chip material can be arranged between the drying device and the extrusion device. A binder can be added to the dried chip material in a feeder. This can be, for example, a thermosetting glue or a thermosetting organic binder that releases water or another liquid during curing or polymerization. Other binders are also possible.

[0025] Furthermore, the addition of a hydrophobic agent is possible. This prevents unwanted water absorption by the extruded chip material and the blocks.

[0026] After adding the agent(s) mentioned, the dried chip material may have a slightly increased moisture content of, for example, 5 to 8% atro, preferably 6 to 7% atro.

[0027] The extrusion system features an extrusion press that produces a virtually continuous, pre-curved strand from the chip material. In the pre-curved strand, the activated binder ensures the desired or required strength of the strand and the blocks. This applies, for example, to a specified nail pull-out strength. The blocks can therefore meet the strength requirements imposed in operation, particularly when used as pallet blocks. They exhibit high compressive strength, impact strength, and fracture strength.

[0028] The extrusion press may have a chip feeder and a driven pressing device, e.g., an oscillating press ram or a press screw. It may also have a binding device for the extruded chip material containing the binding agent, or for the strand itself. The binding device activates the binding agent contained in the chip material. This can be done in various ways.

[0029] The setting device can comprise, for example, a vaporizing device and / or a high-frequency heater. A vaporizing device is advantageous, for example, for a thermosetting glue and its polymerization. For the aforementioned organic binder, a combination of a vaporizing device and a high-frequency heater can be advantageous.

[0030] During steaming, the thermal energy or enthalpy contained in the steam can be released abruptly through condensation in the exposed strand area, ensuring uniform heat dissipation and a significant acceleration of the thermal setting reaction of the strand material. The addition of superheated steam has the advantage of delaying condensation and the phase change, which are evenly distributed across the strand cross-section. Early condensation on the exposed outer surface or mandrel hole surface of the strand can be prevented.

[0031] High-frequency heating can use high-frequency alternating electromagnetic fields to preferentially and locally heat local binder concentrations and moisture precipitation from, for example, an organic binder. Combining steaming and high-frequency heating can reduce the amount of steam introduced and thus the moisture ingress into the strand through synergistic addition. This is advantageous when the blocks are to have low residual moisture and cooling and drying requirements for the blocks can be reduced or avoided. The reduced steam ingress can also improve the surface quality of the strand and thus the blocks produced from it.

[0032] In a thermal setting process for the strand and the binder contained therein, a cooling section of the extrusion press following the setting device is also advantageous.

[0033] Further advantageous embodiments of the invention are specified in the subclaims.

[0034] The claimed system and method may have the following advantageous embodiments. These may be used individually or in any combination.

[0035] In a multi-layer continuous dryer, the multiple layers of chip material can be arranged one above the other and / or next to each other. A stacked arrangement is preferred.

[0036] A particle former can be arranged upstream and / or downstream of the drying device in the system, which changes, in particular reduces, and preferably adjusts the particle size of the chip material.

[0037] Between the drying device and the extrusion device, an addition device can be arranged which adds a binding agent to the dried chip material, in particular a thermosetting glue or a thermosetting organic binding agent.

[0038] An organic binder may release water or other liquid during curing or polymerization.

[0039] An addition device can be arranged between the drying device and the extrusion device, which adds a hydrophobic agent to the dried chip material.

[0040] The extrusion device can comprise a separating device, in particular a saw, located downstream of an extrusion press. The separating device can separate blocks from a strand delivered by the extrusion press.

[0041] An extrusion press may comprise a chip feeder and a driven pressing element, in particular an oscillating press ram. The pressing element may be hydraulically driven, e.g., by a cylinder.

[0042] An extrusion press may have a binding device, in particular a steaming device and / or a high-frequency heater, for the extruded chip material provided with the binding agent. The steaming device may introduce superheated steam into the strand.

[0043] An extrusion press can have a cooling section for the tied strand.

[0044] The invention is illustrated schematically and by way of example in the drawings. In detail: Figure 1: a schematic view of a plant for producing blocks and Figure 2: a schematic representation of a multi-layer continuous dryer.

[0045] The invention relates to a system (1) for producing blocks (3), in particular pallet blocks. The invention also relates to a method for producing said blocks (3), in particular pallet blocks. The blocks (3) are produced from a chip material (2) which comprises small plant particles, in particular small wood particles, e.g., wood particles, wood shavings, wood chips, or the like. The chip material (2) preferably consists essentially of the small plant particles, in particular small wood particles. The small plant particles, in particular small wood particles, are provided with a binding agent.

[0046] Figure 1 shows such a system (1). It has a drying device (4) into which the chip material (2) is fed in the direction of the arrow. The system (1) also includes an extrusion device (10) and other components.

[0047] The chip material (2) originates, for example, from a sawmill and the cutting of fresh wood. Alternatively or additionally, it may consist of processed waste wood or other small plant parts, especially small wood parts. The chip material (2) may contain lignin or other cellulose components.

[0048] At the end of the system (1) and the manufacturing process, the blocks (3) are created from the dried, subsequently extruded and set chip material (2). These are manufactured and used, for example, as solid pallet blocks or as blocks with a through-hole. The blocks (3) preferably have a peripheral shape that is flat, at least in some areas. This can be, for example, a rectangular circumference with chamfered corners. Other block shapes are also possible. The blocks (3) can have a length that is equal to or less than their height and / or width. Alternatively, the blocks (3) can have a significantly greater length and a strip shape.

[0049] The drying device (4) can have one or more dryers. In the embodiment shown, it has an air dryer (21) which is designed as a multi-layer continuous dryer (22) and which directs a heated dry air stream (32) through the chip material (2). In the multi-layer continuous dryer (22), the dry air stream (32) flows through several, e.g. two, chip layers (23, 24) formed from the chip material (2) one after the other. The dry air stream (32) can flow through the chip layers (23, 24) in particular directly one after the other. A free space is arranged between the spatially separated chip layers (23, 24). The flat and, e.g., planar chip layers (23, 24) are aligned with their main plane essentially horizontally and parallel to one another. They preferably have a constant thickness. The chip layers (23, 24) are, e.g.formed by heaping and evenly distributing the bulk chip material (2) on chip material carriers (25,26) explained below.

[0050] The chip layers (23, 24) have different moisture levels or water contents. According to the invention, the dry air stream (32) is directed first through a chip layer (24) with a low moisture level or water content and then through a chip layer (23) with a higher moisture level or water content. The dry air stream (32) is preferably oriented perpendicular to the main plane of the chip layers (23, 24). It extends, for example, vertically, in particular from top to bottom.

[0051] The chip layers (23, 24) can be spatially separated from each other. In the embodiment shown, the plurality of chip layers (23, 24) are Figure 1 and 2For example, they are arranged one above the other in tiers. They are arranged directly above one another, particularly vertically. They can be aligned vertically.

[0052] The chip material (2) and the chip layers (23, 24) pass through the multi-layer continuous dryer (22) in one pass, with the wet chip material (2) entering at an inlet (28) and exiting dried at an outlet (29). The inlet (28) and the outlet (29) can be arranged on different sides of a housing of the multi-layer continuous dryer (22). The inlet (28) is, for example, according to Figure 2 on the lower side of the housing and the discharge (29) above it on the upper side of the housing.

[0053] The chip material (2) and the chip layers (23, 24) are exposed to the dry air stream (32) as they pass through the multi-layer continuous dryer (22). The dry air stream (32) can be uniformly conditioned. The chip layer (24) that is first exposed to the air stream is exposed to the same dry air over its entire surface.

[0054] How Figure 2 As shown schematically, the multi-layer continuous dryer (22) has a heating device (31) and a circulation device (33) for the dry air stream (32). The heating device (31) is arranged upstream of the first chip layer (24) in the air flow direction. It is located, for example, above this chip layer (24). The heating device (31) is designed, for example, as a heat exchanger that is fed with primary energy from waste heat from a power plant, from a furnace or burner, or with thermal energy from any other source.

[0055] In the heat exchanger, the outside can be Figure 2 supplied fresh air can be heated. Alternatively or additionally, it is possible to partially or completely recirculate the dry air flow (32) and feed it into the heating device (31). Figure 2 This possibility is indicated by a dashed line. The heated dry air stream (32) exiting the heating device (31) can have a high temperature of, for example, 90° to 100° C or even higher. The dry air stream (32) can be Figure 2 The entire chip layer (24) is exposed to the entire surface. Its flow cross-section can be adapted to the layer size.

[0056] The circulation device (33) can comprise one or more circulation devices, e.g., fans, for moving the dry air. The heating device (31) and the circulation device (33) can extend over a surface that corresponds to the surface of the preferably flat chip layers (23, 24) and is optionally parallel to this plane.

[0057] The circulation device (33) may comprise one or more additional components. It may, for example, comprise a device for dehumidifying the dry air stream (32) exiting the last layer of chip material (23) through which it passed. This may, for example, be a condensation device. Alternatively or additionally, the circulation device (33) may comprise a device for recovering heat from said exiting dry air stream (32). This may, for example, be a heat exchanger. The recovered thermal energy can be fed to the heating device (31) or to another consumer.

[0058] The circulation device (33) may additionally or alternatively further comprise a device for reprocessing the dry air stream (32). This may be, for example, a filter device, a catalyst, a post-combustion device for solids contained in the dry air stream (32), or the like. The circulation device (33) may discharge the non-recirculated portion of the absorbed dry air stream (32) as exhaust air to an exhaust duct or the like.

[0059] The circulation device (33) is located, for example, below the last layer of chip material (23) through which it passes and receives the dry air stream (32) emerging from this layer. For this purpose, it can, for example, draw in the dry air from above and, if necessary, expel it upwards to the heating device (31). The air stream can be guided in the dryer housing and, if necessary, in air ducts.

[0060] The multi-layer continuous dryer (22) can also have a switchable and, if necessary, controllable bypass for a portion of the dry air flow (32). This can be an external bypass on the dryer housing with one or more external, controllably closable air ducts. Through the bypass (not shown), heated dry air can be directed past the first chip layer (24) directly to the next chip layer (23).

[0061] The multi-layer continuous dryer (22) has several movable and air-permeable chip carriers (25, 26), each for a chip layer (23, 24). In the embodiment shown, the chip carriers (25, 26) are arranged one above the other. They are air-permeable and the drying air stream (32) also flows through them one after the other. The chip carriers (25, 26) can be moved together with the chip layer (23, 24) lying on them in a direction marked by arrows (27) as they pass through. The chip (2) is moved, for example, in two or more chip layers (23, 24) arranged one above the other from the feed (28) to the discharge (29).

[0062] The chip carriers (25,26) and their chip layers (23,24) are successively flowed through by the dry air stream (32) and are Figure 1 and 2 moves in opposite directions (27).

[0063] The drying progress in the chip material (2) changes during the continuous movement in the respective direction of movement (27). The chip material layers (23, 24) are exposed to the dry air stream (32) over a larger and preferably continuous area. The dry air stream (32), which is e.g. vertically directed, moves from the heating device (31) located at the top, vertically downwards to the circulation device (33).

[0064] As the drying process progresses in the direction of movement (27), the temperature of the chip material (2) increases in each chip layer (23, 24). At the same time, the moisture content or water content of the chip material (2) decreases. As the chip material (2) moves along the transport path in the respective direction (27), it becomes increasingly drier and warmer.

[0065] The multi-layer continuous dryer (22) has a transfer device (30) arranged between the, for example, separate chip carriers (25, 26) and their chip layers. In the embodiment shown, the transfer device (30) transports the chip material (2) from the lower chip carrier (25) upwards to the upper chip carrier (26). The chip material (2), which is designed as bulk material, can be transported in any suitable manner, e.g., by a screw conveyor, a conveyor belt, a cyclone-type air conveyor, or the like.

[0066] The transfer device (30) removes the chip material (2) from the lower chip layer (23) from the chip carrier (25) at the end of the conveying path running in direction (27) and transports it to the rear end of the upper chip carrier (26) in direction (27). The chip material (2) is fed onto the chip carriers (25, 26) in a controlled manner and with a predetermined layer thickness, forming the chip layer (24). At the end of the conveying movement, the chip material (2) from the upper chip layer (24) can be discharged and removed in a suitable manner at the discharge (29) either directly or via an intermediate conveyor or the like.

[0067] The movable and air-permeable chip carriers (25, 26) can be of identical or different design. They can be designed in any suitable manner, e.g. as perforated belts, discs or rings. These can move in the respective direction (27) for the chip transport. This can be a circular movement, for example. A chip carrier (25, 26) designed, for example, as a circular endless belt can transport the chip in a straight, linear direction (27). The chip (2) or the chip layer (23, 24) is transported on the upper run of the air-permeable conveyor belt. In another design with a preferably flat disc or ring shape, the chip carrier (25, 26) can rotate about an axis of rotation directed, e.g., transversely to the main plane of the chip layer (23, 24), e.g., vertically. It can perform a circular orbital movement with a correspondingly curved direction (27).The plurality of, in particular two, chip carriers (25, 26) and chip layers (23, 24) rotate in opposite directions (27).

[0068] In the illustrated embodiment of the chip layers (23, 24) and chip carriers (25, 26) arranged one above the other in tiers, the wet chip is transferred from the feed (28) to the lower chip carrier (25), where the lower chip layer (23) is formed in a controlled manner. The upper chip layer (24) on the upper chip carrier (26) has already undergone part of the drying process. The dry chip is finally discharged to the discharge (29).

[0069] The fresh dry air stream (32), which preferably exits the heating device (31), is first directed onto the upper, already pre-dried chip layer (24). Here, the dry air stream (32) cools and simultaneously absorbs moisture or water from the chip layer (24). This occurs gradually in direction (27) according to the respective drying progress.

[0070] Subsequently, the slightly moistened and cooled dry air stream (32) preferably flows directly to the next lower chip layer (23) with its lower temperature and higher moisture content, where the dry air stream (32) cools further and absorbs moisture or water content. This also occurs gradually according to the drying progress in the direction (27).

[0071] Due to the opposite directions (27) and drying progress during the transport of the chip layers (23, 24), the dry air flow (32) absorbs essentially the same moisture everywhere after flowing through the chip layers (23, 24) and releases essentially the same temperature.

[0072] In the upper and relatively dry chip layer (24), the chip has the highest temperature and the lowest moisture content at the front end in direction (27) and facing the discharge (29). In the area of the lower chip layer (23) projected below in the direction of flow, the chip that has just been fed in has the highest moisture content and the lowest temperature. In the said dry and hot area of the upper chip layer (24), relatively little temperature is released from the dry air stream (2) and relatively little moisture is absorbed. In the lower, colder and wetter area of the chip layer (24) through which the air subsequently flows, more temperature is released from the dry air stream (32) and more moisture is absorbed.

[0073] At the opposite end of the chip carriers (25, 26) and the respective transport movement, the conditions are more balanced. In this end region of the upper chip layer (24) near the converter, the temperature is lower and the moisture in the chip (2) is higher than at the discharge end. Accordingly, more temperature is absorbed from the preferably equally conditioned dry air stream (32) and more moisture is released to the dry air stream (32). In the region of the lower chip layer (23) projected below in the flow direction, the temperature in the chip (2) is somewhat higher and the moisture is already lower than at the supply end due to the drying progress. As a result, less temperature is absorbed from the dry air stream (32) and less moisture is released to the dry air stream (2).

[0074] In a linear, belt-shaped chip carrier (25, 26), the feed (28) and the discharge (29) are arranged, for example, on one side of the carrier and the transfer device (30) is arranged on the other, opposite side of the carrier. In a circumferentially rotating, disc-shaped or ring-shaped chip carrier (25, 26), the feed (28) and the discharge (29) as well as the transfer device (30) can be arranged closely adjacent to one another at a circumferential location. In a ring-shaped chip carrier (25, 26), a possible

[0075] The dry air is returned through the free ring interior.

[0076] The drying device (4) may comprise one or more additional dryers (20). This may, for example, be Figure 1a mechanical dryer. Such a dryer (20) can be designed, for example, as a squeezing device or in another manner. The additional, particularly mechanical, dryer (20) can, for example, be arranged upstream of the air dryer (21) or multi-layer continuous dryer (22) in the feed direction of the chip material (2).

[0077] The dryers (20, 21, 22) can each have suitable sensors for detecting drying-relevant physical parameters, e.g., temperature and humidity, of the chip material (2) and the drying air flow (32), as well as a controller and devices actuated by the controller for mechanically influencing the chip material (2) and the chip layers (23, 24). These can be, for example, shakers, strippers, turners, or the like. Sensors can also detect the physical parameters, in particular movement parameters, of the chip carriers (25, 26), the transfer device (30), the heating device (31), and the circulation device (33) and can be used to control and, if necessary, regulate them.

[0078] The system (1) can have at least one particle former (5, 6) that modifies, in particular reduces, and preferably also adjusts the particle size of a chip (2). Such a particle former (5, 6) can be designed, for example, as a hammer mill or pulse breaker, which uses ultrasonic pulses to break up the supplied particles of the chip (2), thereby reducing the particle size.

[0079] A particle former (5) can, for example, be located upstream of the air dryer (21) or the multi-layer continuous dryer (22) in the feed direction of the chip material (2). The particle former (5) can be located between a possible mechanical dryer (20) and the air dryer (21). Alternatively, it can be arranged upstream of the possible mechanical dryer (20). It can also be combined with the possible mechanical dryer (20).

[0080] Such an upstream particle former (5) can perform a rough treatment of the chip material (2) and produce a particle size suitable for subsequent air drying. This particle size may be too large for the extrusion process. In this case, at least one further particle former (6) can be arranged downstream of the air dryer or air drier (21) in the transport direction of the chip material. Here, the particle size of the chip material (2) suitable for the subsequent extrusion process can be produced, e.g., with a fine treatment. Figure 1 shows this embodiment. As a variation, only one of the particle formers (5, 6) can be present, if required, and this can be arranged upstream or downstream of the air dryer (21) or the multi-layer continuous dryer (22).

[0081] In the area between the drying device (4) and the extrusion device (10), the system (1) can have additional components that act on the dried chip material (2). This can be, for example, a storage device (9). The storage device (9) is dispensable in the preferred embodiment and is therefore shown in dashed lines.

[0082] Furthermore, one or more addition devices (7) can be arranged between the drying device (4) and the extrusion device (10). This can be, for example, an addition device (7) that adds a binder to the dried chip material (2), which can be activated during the extrusion process and imparts strength to the chip material (2) pressed into a strand (15). The binder can be designed in any suitable way. It can, for example, be a thermosetting glue. Alternatively or additionally, another binder can be designed, possibly a thermosetting organic binder, which separates water or another liquid during curing or polymerization. This can, for example, be a Maillard binder.

[0083] A hydrophobicizing agent can also be added to the dried chip material (2). This can be, for example, a wax. A further addition device (8) can be provided for this purpose. The order of the addition devices (7, 8) can depend on the type of agent being added. Alternatively, several addition devices (7, 8) can also be combined into a single unit.

[0084] In the embodiment shown, the extrusion device (10) arranged downstream in the transport direction of the dried chip material (2) comprises an extrusion press (11) and a separating device (18) as well as, if appropriate, a subsequent conveyor line (19).

[0085] The extrusion press (11) produces a virtually endless, bound strand (15) from the dried chip material (2) with the binding agent, preferably with a straight extension. This strand is advanced continuously or intermittently in a straight pressing direction (14).

[0086] For this purpose, the extrusion press (11) has a chip feed (12) facing the one or more feed devices (7, 8) and a driven pressing element (13). The pressing element (13) is designed, for example, as an oscillating press ram or as a rotating press screw or the like. In a collecting and pressing chamber and a recipient, the emerging strand (15) is formed from the still loosely pressed chip (2). The rod-shaped, straight strand (15) can have a rounded or prismatic circumferential contour.

[0087] The strand (15) is then transferred in the pressing direction (14) into a binding device (16) of the extrusion press (11), where the binding agent in the strand (15) is activated. The binding device (16) can be single-part or multi-part. It can, for example, comprise a vapor deposition device. Additionally or alternatively, a high-frequency device can be present. Depending on the type of binding agent, the binding device (16) can also comprise a different type of activation device.

[0088] In a steaming device, the strand (15) is exposed to steam at the outer shell and / or at an internal mandrel hole. This can be saturated steam or superheated steam. The superheated steam is, for example, highly pressurized and in pure gas form. It can have a suitable pressure and a correspondingly high temperature for this purpose. The binding device can also include a suitable steam generator. The superheated steam can gradually cool down in the strand after insertion and condense with a delay during further advance.

[0089] The aforementioned high-frequency heating operates, for example, with alternating electromagnetic fields. It can have one or more field generators arranged on the strand (15), which may be preceded by a replaceable and field-permeable adaptor that contacts the strand (15) and is adapted to the outer strand contour. High-frequency heating is particularly suitable for an organic binder, in particular a Maillard binder.

[0090] A vapor deposition system and a high-frequency heater can be used together or in combination. They can work synergistically. Alternatively, a vapor deposition system or a high-frequency heater can be used.

[0091] The extrusion press (11) can have a downstream cooling section (17) in the pressing direction (14) or in the feed direction of the strand (15), in which the strand (15), possibly heated by the activation of the binder, can cool. Cooling can take place in ambient air or with the active use of a coolant and heat sinks.

[0092] The tied strand (15) then moves in the pressing direction (14) into the separating device (18). This separates the blocks (3) in the desired format from the virtually endless strand (15). The separating device (18) can be designed, for example, as a saw.

[0093] The blocks (3) can be separated, for example, by a separation transverse to the pressing direction (14), e.g., in the manner of a cross-cut saw. In another embodiment, the separating device (18) can be designed as a compartmentalizing unit which separates and divides the rod-shaped strand (15) with its given end face into several individual blocks and / or strips with smaller end faces. Different separating cuts can be made transversely and longitudinally to the pressing direction (14). In particular, several differently inclined separating cuts can also be made along the strand axis or the pressing direction (14).

[0094] The separating device (18) can further comprise a detection device for the separated blocks (3). This can be, for example, a weighing device and / or a measuring device for the block format. The block densities can also be detected directly or indirectly. Furthermore, it is possible to detect the temperature and / or residual moisture content or other physical parameters of the blocks (3).

[0095] The collection device can also be integrated into the conveyor line (19). The blocks (3) are transported along the conveyor line (19). They can then be temporarily stored as needed and subsequently assembled and packaged, in particular palletized, in a suitable manner, e.g., in layers.

[0096] Modifications of the embodiment shown and described are possible in various ways.

[0097] In the multi-layer continuous dryer (22), the chip layers (23, 24) and the chip carriers (25, 26) can be arranged next to one another, wherein the air flow (32) is deflected in a suitable manner after flowing through the said first chip layer (23) to the next chip layer (23), e.g. through a flow shaft or the like. The chip carriers (25, 26) can be designed for this purpose, e.g. as parallel, endless conveyor belts. They can also be located at the same height. A transfer device (30) can be designed, e.g., as a cross conveyor. As a further variation, the chip carriers (25, 26) can be designed and arranged as concentric ring carriers. In a further modification, the chip carriers (25, 26) can be connected to one another and, e.g., form an air-permeable circulating conveyor. The chip layers (23, 24) are formed by different areas in a uniform chip bed.The supply and removal of the chip material (2) can take place on the same side of the dryer housing. The heating device (31) and the circulation device (33) can be arranged in a correspondingly adapted manner.

[0098] The design and arrangement of the heating device (31) and the circulation device (33) can vary. The two devices can also be combined. In the illustrated embodiment, the circulation device (33) draws in the dry air stream (32). Alternatively, it can expel the dry air stream (32). The heating device (31) and / or the circulation device (33) can also be present in multiples. LIST OF REFERENCE SYMBOLS

[0099] 1System 2Chips, small plant parts 3Block, pallet block 4Drying device 5Particle former, hammer mill 6Particle former, hammer mill 7Binding agent addition device 8Water repellent addition device 9Accumulator 10Extrusion device 11Extrusion press 12Chips feed 13Pressing device, press ram 14Pressing direction 15Strand 16Binding device 17Cooling section 18Separating device, saw 19Conveyor section 20Mechanical dryer, squeezing device 21Air dryer 22Multi-layer continuous dryer 23Wet chip layer 24Dry chip layer 25Chip carrier 26Chip carrier 27Direction, flow direction 28Feed 29Discharge 30Transfer device 31Heating device 32Drying air flow 33Circulation device

Claims

1. System for manufacturing blocks (3) from a chip material (2) which consists of small plant parts, in particular small wood parts, and is provided with a binding agent, wherein the system (1) has an extrusion device (10) and an upstream drying device (4) for the chip material (2), wherein the drying device (4) has an air dryer (21) which directs a heated drying air flow (32) through the chip material (2), characterized in that the air dryer (21) is formed as a multi-layer continuous dryer (22) in which the drying air flow (32) flows through a plurality of chip material layers (23,24) with different degrees of humidity in succession, in particular in direct succession, wherein the drying air flow (32) is directed first through a chip material layer (24) with a low degree of humidity and thereafter through a chip material layer (23) with a higher degree of humidity.

2. System according to Claim 1, characterized in that the chip material (2) is able to be transported continuously through the multi-layer continuous dryer, wherein the wet chip material (2) enters at an inlet(28) and exits in a dried state at an outlet (29).

3. System according to Claim 1 or 2, characterized in that the chip material layers (23,24) are subjected to a uniformly conditioned drying air flow (32) during their continuous movement in the multi-layer continuous dryer (22).

4. System according to any one of the preceding claims, characterized in that the multi-layer continuous dryer (22) has a plurality of movable and air-permeable chip material supports (25,26) for in each case one chip material layer (23,24), wherein the chip materials supports (25,26), which are preferably formed as belts, disks or rings, are disposed on top of one another and / or next to one another, and are successively passed through by the drying air flow (32).

5. System according to Claim 4, characterized in that the chip material supports (25,26) and chip material layers (23,24), which are successively passed through by the drying air flow (32) are moved, preferably so as to circulate, in opposite directions (27).

6. System according to one of the preceding claims, characterized in that the multi-layer continuous dryer (22) has a transfer unit (30) for the chip material (2), which is disposed between separate chip material supports (25,26).

7. System according to one of the preceding claims, characterized in that the multi-layer continuous dryer (22) has a heating device (31) and a recirculating device (33) for the drying air flow (32).

8. System according to one of the preceding claims, characterized in that the multi-layer continuous dryer (22) has a switchable bypass for the drying air flow (32).

9. System according to one of the preceding claims, characterized in that the drying device (4) has a mechanical dryer (20), in particular a squeezer, which is disposed upstream of the air dryer (21).

10. System according to one of the preceding claims, characterized in that the drying device (3) generates a degree of humidity of the chip material (2) at the end of the drying of 2 - 4 % atro.

11. System according to one of the preceding claims, characterized in that a particle former (5,6), which modifies, in particular reduces, and preferably sets the particle size of the chip material (2) is disposed upstream and / or downstream of the drying device (4).

12. System according to one of the preceding claims, characterized in that the extrusion device (10) has an extrusion press (11) which generates a quasi-continuous, consolidated strand (15) from the dried chip material (2).

13. Method for producing blocks (3) from a chip material (2) which consists of small wood parts and is provided with a binding agent, by means of an extrusion device (10) and an upstream drying device (4) for the chip material (2), wherein the drying device (4) directs a heated drying air flow (32) through the chip material (2) by means of an air dryer (21), characterized in that the drying device (4) directs the heated drying air flow (32) through the chip material (2) which is disposed in a plurality of chip material layers (23, 24), wherein the drying air flow (32) flows through a plurality of chip material layers (23, 24) with different degrees of humidity in succession, in particular in direct succession, wherein the drying air flow (32) is directed first through a chip material layer (24) with a low degree of humidity and thereafter through a chip material layer (23) with a higher degree of humidity.

14. Method according to Claim 13, characterized in that the chip material (2) is transported continuously through the multi-layer continuous dryer and transferred between the separately disposed chip material layers (23,24), wherein the wet chip material (2) enters at an inlet (28) and exits in a dried state at an outlet (29), wherein the drying air flow (32) is directed first through a chip material layer (24) with a low degree of humidity and thereafter through a chip material layer (23) with a higher degree of humidity, wherein the chip material (2) is moved, preferably so as to circulate, in opposite directions (27) in the chip material layers (23,24) which are successively passed through by the drying air flow (32).

15. Method according to Claim 13 or 14, characterized in that the drying air flow (32) is preferably aligned perpendicularly to the main plane of the chip material layers (23,24) and extends vertically from top to bottom.