Method and apparatus for producing a dried fibrous web

Abstract

The invention relates to methods for producing a dried fibrous web (309), preferably a tissue, paper or cardboard web or a nonwoven web, comprising the following steps: a) raw material preparation of cellulose-containing fibers (200) to individual fibers and / or fiber bundles (209); b) forming the individual fibers and / or fiber bundles (209) in a fiber-air volume flow to form a planar fiber fabric (300), in particular on a forming belt (40) by a dry forming process; c) solidifying the planar fiber fabric (300) to produce a fibrous web (309), in particular by applying pressure and / or temperature in at least one press gap (80, 83, 84).The process comprises in step a) the following further steps: S1 Providing a fiber-air volume flow (207) before or after a first fiberizing device (222), S2 Separating the fiber (209) from the provided fiber-air volume flow (207) and feeding the fiber (209) into a compaction device (250), S3 Compacting the fiber (209) in the compaction device (250), S4 Detaching, in particular knocking off, the fiber (209) compacted in step S3.

Description

The invention relates to a method for producing a dry laid fibrous web, in particular a tissue, paper or board web or a nonwoven web, comprising the following steps: a) raw material processing of pulp-containing fibers to form individual fibers and / or fiber bundles; b) forming the individual fibers and / or fiber bundles in a fibrous material air volume flow to form a flat fiber web, in particular on a forming belt by a dry forming method; c) consolidating the flat fiber web to produce a fibrous web, in particular by applying pressure and / or temperature in at least one press nip.Fibrous webs, in particular paper, board or tissue webs, have been produced in the past and are still produced at an industrial level almost exclusively by wet processes. For this purpose, if waste paper is not used, bale pulp is usually dissolved in a vat in large amounts of water, so that a fiber suspension is obtained which consists to the extent of about 99% by weight of water and only to the extent of about 1% by weight of fibers. The fiber suspension is then applied to a forming wire via a headbox for sheet formation. The fibrous web is then dewatered or dried by pressure and heat until it can be wound up at the end or processed in another way. The wet process has the advantage that hydrogen bonds form between the individual fibers during dewatering or drying, which hydrogen bonds impart the necessary strength to the fibrous web. However, a disadvantage of this process is that large amounts of energy are required for drying the fibrous web. Especially against the background of the global climate change, therefore, alternatives to this classic wet method are intensively sought.As an alternative to the wet process, the dry air-laying process is already known, among others, in which fibers are laid in the substantially dry state to form a fibrous web. To impart a certain strength to the fibrous web, small amounts of water are added to form hydrogen bonds and / or other binders. This results in significantly less energy having to be applied for the drying.In dry air laying methods known from the prior art, fluff pulp material, known as fluff pulp, is used. The fluff pulp material is provided as a roll stock, wherein a fluff pulp web wound into a roll has not only a defined thickness and a defined width, but also further predefined properties, which enable a smooth further processing. Thus, the fluff pulp usually has a high purity level, a uniform density of, for example, less than 0.65 g / cm 3, and a uniform moisture content and can be very easily defibrated in the dry state, which is also referred to as "defibrating". Lint pulp material as a roll product is distinguished by a good running property, a low comminution energy required and a low knot content. Nodes are agglomerates of individual fibers and fines. The fluff pulp material used is usually already processed according to the desired material properties and has a desired fiber composition, for example a certain long and short fiber content. In the production of nonwoven and dry laid products from fluff pulp material, the roll stock is usually unwound at a defined web speed, fed to dry fiberization (defibration) and then fed to a nonwoven or dry laid machine (production machine).Such a process is described in document WO 2023 / 280812A1. Processing of the lint pulp material beyond the fiberizing is dispensed with, since the roll stock used already has the properties required with regard to the further processing. It is characteristic of the known production method that during the unwinding of the lint pulp material from the material roll at a constant web speed, a continuous, in particular constant-time mass flow of pulp material is produced due to the well-defined properties of the lint pulp web, which mass flow is likewise continuously supplied to the production machine. The mass flow is adjusted via the web speed during the unwinding of the lint pulp material. Finally, the basis weight of the nonwoven or dry-laid product is also adjusted via the mass flow of the material supplied to the production machine.Furthermore, for example, in the publications U.S. Pat. No. 2020 / 0 149 219 A1, U.S. Pat. No. 2021 / 0292970 A1, DE 10 2023 126 607 A1, DE 10 2023 129 655 A1, DE 10 2023 129 657 A1, methods and apparatuses for producing a dry-laid fibrous web are disclosed.In summary, production processes for airlaid products or nonwoven fabrics have particular requirements on the starting material and make the use of conventional pulp materials in commercially available bundles, for example pulp in the form of pulp bales, which is composed of pulp mats stacked one on top of the other, as is used in the various wet-produced types of paper, for example in tissue production, virtually impossible without further processing. Compared to lint pulp material, however, pulp bales have significant advantages in terms of market price, their raw material availability and also the sustainability of production. However, in the prior art, pulp bales or pulps generally which are not supplied as rollware having defined dimensions and a defined density cannot be processed directly to the required continuous mass flow (mass per time) of defibrated pulp material. In addition to fiberizing, further processing steps are also necessary, for example cleaning and / or sorting, which in the prior art likewise prevent a continuous material flow of fiberized pulp material. For production on an industrial scale, a high, continuous production speed or fibrous web speed of greater than or equal to 300 m / min, in particular greater than or equal to 400 m / min, in particular greater than or equal to 500 m / min, in particular greater than 600 m / min or greater than 800 m / min, and a width of the continuously produced fibrous web of greater than or equal to 0.5 m, in particular greater than or equal to 1 m, in particular greater than or equal to 2.7 m, to less than or equal to 10 m are sought, so that a high mass flow of processed fibrous material has to be provided continuously. Therefore, it is not possible to obtain a suitable material flow, in particular with the methods known in the prior art, if pulp bales or similar fibrous material are to be processed as starting material in a raw material treatment.It is therefore the object of the present invention to solve or at least minimize the aforementioned problems from the prior art. In particular, a method for producing a dry-laid fibrous web is to be specified, by means of which a continuous material inflow and in particular a continuous mass flow of fibrous material can be ensured and the quality of the end product and the efficiency of the production process can thus be improved.This object is achieved by the independent claims. The dependent claims are concerned with advantageous developments of the invention.This object is achieved in concrete terms in that step a), which comprises the raw material preparation, has the following further steps:S 1 providing a fibrous-material air volume flow,S 2 separating the fibrous material from the provided fibrous material air volume flow and feeding the fibrous material into a compacting device,S3 Compacting the fibrous material in the compacting device,S 4 Detachment, in particular beating, of the fibrous material compacted in step S 3.Such an embodiment has the advantage that the mass flow of the provided fibrous material can be provided continuously within the process of raw material treatment and adapted to the respective need. Fluctuations in the mass flow can be smoothed or reduced. In this case, it may be the case, for example, to realize a mass flow which is as homogeneous as possible with, for example, fluctuations of at most 4% of the mass flow of the fibrous material, in particular fluctuations of at most 2% of the mass flow of the fibrous material. The method makes it possible to adjust or control the mass flow to the smallest possible fluctuations, in particular fluctuations of less than 2%, preferably less than 1%, particularly preferably less than 0.75%, of the basis weight of the fibrous web produced. For example, in the case of a high mass flow of fibrous material, in the fibrous material air volume flow provided in step S 1 and a lower predetermined or required mass flow of fibrous material, at least one of the steps of the proposed method can be controlled for a downstream production step such that a temporarily "excess" fibrous material is temporarily stored or buffered in the compacting device. The intermediate storage in the compacting device can be effected in particular by compacting the fibrous material in the compacting device. The buffering can be effected, for example, by the fibrous material being more strongly compressed in step S 3 and / or less fibrous material being detached from the compressed fibrous material again in step S 4. As a result, a variation in the mass flow of the fibrous material after step S 4 can also be compensated or attenuated or reduced. This makes it possible for the mass of fibrous material in the end product, i.e. in the fibrous material web produced or even already in the dry-laid flat fibrous material laid scrim, to be homogeneous uniformly or continuously.It is furthermore advantageous that sub-processes in raw material processing and in dry fibrous web production can be decoupled from upstream or downstream sub-processes, despite the superordinate continuous overall process. Thus, sub-processes and also the entire production process can be improved with regard to their efficiency and with regard to the quality of the end product.Within the process of raw material processing of pulp-containing fibers to individual fibers and / or fiber bundles, the fibrous material-air volume flow in step S 1 can be provided, for example, at about 4000 m 3 / h, wherein about 500 kg / h of fibrous material can be present. In other words, the ratio can be, for example, about 1 kg of fibrous material in 8 m 3 of air volume flow. A fibrous-air volume flow is in this respect a volume flow which contains air and fibrous material. The air essentially serves as a carrier for the fibrous material. The fibrous material is dissolved or distributed in the air stream, so that it can be transported in the form of the fibrous material-air volume flow. A mass flow of fibrous material, on the other hand, can have different forms. For example, it can be designed as a fibrous mat which is transported or moved. However, a mass flow of fibrous material can likewise relate to the fibrous material in a fibrous material-air volume flow.The fibrous material-air volume flow provided in step S 1 can be provided, for example, before or after a first defibering device. A first fiberizing device can be designed, for example, as a hammer mill, preferably a hammer mill with radial material feed from the outside or a hammer mill with axial material feed or a disk mill, in which the fibrous material is fiberized until individual fibers with individualized nodes form. Such individual fibers can then be distributed in a highly resolved manner in the supplied fibrous material-air volume flow. A defibrating device, in particular a second defibrating device, can likewise be designed, for example, as a hammer mill, preferably a hammer mill with radial material supply from the outside, or a hammer mill with axial material supply, or a disk mill, to which the mass flow or the fibrous material-air volume flow is supplied. This can then fiberize the high-resolution, continuous mass flow of fibrous material or fibrous material-air volume flow until essentially only individual fibers are still present, preferably free of nodes or only with a low node content.The air of the fibrous material-air volume flow provided in step S 1 is substantially completely separated from the fibrous material in the separator in step S 2. The separated fibrous material is then introduced into a compacting device. For example, the fibrous material can fall into a hopper or shaft of a compacting device. For example, when the fibrous material is introduced into the compacting device substantially by the influence of gravity, the fibrous material is loosely deposited and only slightly compacted, for which reason it encloses a small amount of air.A compacting device serves for this purpose and is designed to compact the fibrous material. For this purpose, a compacting device can have various suitable designs or operating principles. The compacting device has a volume for receiving fibrous material. A vibration or impact compacting device can be arranged on this, for example, which is configured to compress the fibrous material contained in the volume by means of mechanical impacts and / or vibration. The compacting device can likewise be designed, for example, as an extruder which presses the fibrous material through an in particular narrow opening in order to compact it. Or it may have a press nip connected to the volume, with two or more rollers which pass the fibrous material between them and thereby exert a compacting pressure on the latter. In particular, the fibrous material is compressed within the volume or in direct connection with the volume of the compression device, so that the compressed fibrous material can also be stored or buffered at least partially within the volume. Accordingly, in particular the volume of the compacting device constitutes a buffer or intermediate store of the fibrous material.The fibrous material can be compacted in step S 3 for example to such an extent that in particular a fibrous material mat is formed. Such a fibrous mat can be designed, for example, continuously, comprise a certain thickness and density and be shaped in a self-supporting manner. However, it is also possible for the compressed fibrous material from step S 3 to be compressed only to such an extent that the fibrous material is formed compressed but not self-supporting, that is to say holding its shape. In other words, it is possible to compact the fibrous material to such an extent that in particular a fibrous material mat is formed which retains its shape even when exposed to an external force. The fibrous material can likewise also be compacted to a lesser extent, so that the conveying of the fibrous material produces a mass flow of compacted fibrous material which, although compacted, is not so far that a self-supporting fibrous material mat is produced. Thus, it is just not so far that it retains its shape even under the action of an external force. A type of fibrous material composite can be formed in this case, such that the fibers have a certain hold with respect to one another, but this does not extend to such an extent that the composite also retains its shape outside the compacting device. In particular, the degree of compaction of the fibrous material by the compaction device can be regulated in the proposed method.In step S 3, the fibrous material can be compacted, for example, with a ratio in the range from approximately 1 to 10 with respect to its volume after the separation in step S 2 and the introduction and the loose separation in the compacting device. In other words, the fibrous material can be compacted to one tenth of its original volume in the loosely deposited state. However, it is also possible to compress the fibrous material in the compacting device in a ratio less than or greater than 1 to 10. In particular, the fibrous material can be compacted at a ratio of at least 1 to 4, in particular about 1 to 5, in particular about 1 to 6, in particular about 1 to 7, in particular about 1 to 8, or in particular about 1 to 9. In the same way, the fibrous material can also be compacted to a greater extent in the compacting device, such as in particular in a ratio of about 1 to 11, in particular about 1 to 12, in particular about 1 to 13, in particular about 1 to 14, in particular about 1 to 15, or in particular about 1 to 16, or even in a range of up to 1 to 20, wherein the entire range of 1 to 4 to 1 to 20 is intended to be indicated as suitable.Detachment of the fibrous material in step S 4 is understood to mean that a mass flow or individual fibers or fiber bundles possibly also of relatively large circumference, such as a fibrous material detachment piece, is detached again from the fibrous material compacted in step S 3, in particular in a predetermined mass flow. The term "fiber detachment piece" or "fiber stock removal piece" is understood to mean that a plurality of individual fibers and / or a plurality of fiber bundles are present in the form of a consolidated, coherent, in particular larger, piece, preferably a fiber mat piece. For example, a knocking-off or other detachment device can be provided for this purpose. In this case, for example, a knocking-off device can knock off or release a predetermined mass flow (mass per time) from a fibrous mat produced in the preceding step S 3. For example, it is also possible to detach fibrous material by means of an inflow of air, in particular compressed air or an air volume flow. A knocking-off or detachment device can also have further suitable designs or operating principles. For example, the compressed fibrous material can be detached by means of a first or a further defibering device or a comminution device, for example a comminution roll or a hammer mill, to which the compressed fibrous material is fed, for example in the form of a fibrous mat.The method can additionally comprise a step S 5: supplying an air stream to the detached fibrous material to form a fibrous material-air volume flow with, in particular, constant mass flow of fibrous material.By supplying an air flow, the detached fibrous material can be dissolved into a fibrous material-air volume flow and transported in a simplified manner. The air serves as a carrier by means of which the detached fibrous material can be transported further in the same form in which it has also been fed in step S 1 of the method. It is thus possible for sub-processes of the overall process to be advantageously separated or coupled and mass flow fluctuations of the fibrous material between sub-processes of the raw material treatment to be compensated for. It is likewise possible for further method steps or devices, for example at least one in particular further fiberizing device, to be interposed between the substeps S 4 and S 5.Furthermore, in one embodiment of the method, the air separated in step S 2 can be supplied in step S 5 at least partially as an air stream for forming the fibrous material-air volume flow, wherein in particular only the air separated in step S 2 can be supplied.In other words, the air separated from the fibrous material-air volume flow provided in step S 1 in step S 2 is diverted and, after the compaction and the detachment of the fibrous material, at least partially fed back to the latter in order to resume the detached fibrous material, in particular with a predetermined mass flow. Such a bypass is also advantageous in that the previously separated air does not have to be additionally processed and dust and individual fibers which have remained in the air stream after the separation do not have to be separated out of the process in a complicated manner as waste, but rather can be used further as filler in the dry-laid fibrous web.An embodiment of the method can additionally comprise the step S 6: supplying the detached fibrous material or the formed fibrous material-air volume flow to an in particular further defibering device.Step S 6 can be carried out, for example, after step S 4 or else after step S 5. The fiberizing device, which can be designed, for example, as a hammer mill, can be a first, a second or also a third fiberizing device. For example, a first fiberizing device, which is arranged in particular upstream of the compacting device, can be designed such that only the first part of the fiberizing work takes place therein and, for example, the fiberizing devices such as tooth sets or the like of this first fiberizing device are designed to be rather coarse. The fibrous material which is fed to this first defibering device can have, for example, a greater proportion of nodes and fiber bundles which are largely dissolved in the defibering device. A second or further fiberizing device, on the other hand, can be designed for a more required, in particular fine fiberizing work, and the corresponding fiberizing devices such as tooth sets can be designed to be rather fine. Such an at least two-stage embodiment of the fiberizing work can have a reduced energy requirement with the same overall size in comparison to a single fiberizing device and can enable an improved quality of fiberizing. The proportion of nodes and fiber bundles contained can thus be minimized and the quality of the dry laid final product can be improved, for example.In one embodiment of the method, at least one of the following variables can be regulated in order to obtain a predetermined mass flow of fibrous material detached in step S 4:the mass flow of the fibrous material of the fibrous material air volume flow provided in step S 1,the compression ratio of the compression in step S3, and / orthe mass flow of the fibrous material removed in step S4.A predetermined mass flow of fibrous material detached in step S 4 can be determined, for example, from the demand in downstream processes. In this respect, the required mass flow can be determined for a method step which in particular follows the raw material treatment, and this required mass flow can be predefined for the method as a predetermined mass flow of fibrous material to be separated in step S 4. The mass flow required for a subsequent method step can be determined, for example, on the basis of the mass of fibrous material contained in the flat fibrous material produced in step b), i.e. during the forming of the individual fibers and / or fiber bundles in a fibrous material-air volume flow to form a flat fibrous material.The mass flow required for a subsequent process can also be determined, for example, on the basis of the mass of fibrous material contained in the fibrous material web consolidated in step c). It is also possible that a predetermined or desired mass of fibrous material in the end product determines the predetermined mass of fibrous material which is detached in step S 4. In order to form a predetermined fibrous-material air volume flow in an optionally carried out step S 5, the volume flow of the supplied air flow can additionally or alternatively be regulated in step S 5.According to the invention, the method additionally comprises the step S0: ascertaining the mass flow of the fibrous material of the fibrous material-air volume flow provided in step S1.By determining the mass flow of the fibrous material and / or the volume flow in combination with the fibrous material concentration in the volume flow of the fibrous material air volume flow provided in step 1, the mass flow of fibrous material is known, which is fed to the compacting device. This can be taken into account, for example, in the regulation of at least one of steps S 1 to S 5. Step S 0 can be carried out, for example, before step S 1 and / or between step S 1 and step S 2.In one embodiment of the method, the determined mass flow of the fibrous material of the fibrous material-air volume flow provided in step S 1 and / or a predetermined mass flow of the fibrous material detached in step S 4 resulting in particular from a method step downstream of the raw material treatment can be taken into account in the regulation of at least one of steps S 3, S 4 and / or S 5.In this case, both the mass flow of the fibrous material provided in step S 1 in the fibrous material-air volume flow and the desired mass flow of the fibrous material determined, for example, by a predetermined mass of fibrous material in the dry laid fibrous material laid scrim can be used for regulating subsequent process steps. For example, in the case of a large mass flow of the fibrous material in the provided fibrous material air volume flow and a lower predetermined or required mass flow of the fibrous material detached in step S 4, steps S 3, S 4 and / or S 5 can be regulated in such a way that the temporarily excess fibrous material is temporarily stored or buffered in the compacting device. This can be done, for example, by the fibrous material being more strongly compressed in step S 3 and / or less fibrous material being detached from the compressed fibrous material again in step S 4. As a result, possible fluctuations in the mass flow of the fibrous material detached in step S 4 can also be compensated or attenuated or a fluctuation range can be reduced. As a result, the mass of fibrous material in the fibrous material laid scrim or in the fibrous material web is more uniform or continuously homogeneous.In one embodiment of the method, the mass of fibrous material contained in the compacting device can be determined and taken into account in the regulation of the mass flow of the fibrous material of the fibrous material-air volume flow provided in step S 1, in particular in order to keep the quantity or the volume of the fibrous material contained in the compacting device within a predetermined range. Alternatively or additionally, the mass of fibrous material contained in the flat fibrous web laid by the dry forming device can be determined and taken into account in the regulation of the mass flow of the fibrous material of the provided fibrous material-air volume flow in step S 1. Alternatively or additionally thereto, the mass of fibrous material contained in the consolidated fibrous material web can also be determined and taken into account in the regulation of the mass flow of the fibrous material of the fibrous material-air volume flow provided in step S 1.In this way, the mass flow of the fibrous material supplied in step S 1 can be regulated depending on the required mass flows of the subsequent steps. If, for example, the fiber mass in the flat fibrous web is increased, the mass flow of fibrous web provided in step S 1 can be reduced. This embodiment is particularly advantageous because the method can thus be adapted to connected sub-processes and fluctuations in relation to the mass of the fibrous material or the mass flow during the supply or in the end product can be adapted or adjusted. It is likewise possible, instead of or in addition to the determination of the mass of fibrous material contained in the flat fibrous web laid by the dry-forming device, also to determine the mass of fibrous material contained in the dry-laid fibrous web, in particular before the reeling.In one embodiment, by determining the mass of fibrous material contained in the compacting device, the requirement for the mass flow of the fibrous material provided can be determined for step S 1. If, for example, the mass of fibrous material contained in the compacting device is rather low, it may not be possible to react briefly to an increased required mass flow for downstream process steps, and there is the risk that not enough fibrous material can be provided for the further, in particular continuous, production process. There is therefore a need to increase the mass flow of the fibrous material provided in step S 1. On the other hand, the mass of fibrous material contained in the flat fibrous web or the mass of fibrous material contained in the fibrous web can also be taken into account in the regulation of the mass flow of fibrous material provided in step S 1 in order to ensure continuous operation and the provided quality of the produced fibrous web. If, for example, the mass of fibrous material contained in the flat laid fibrous web or the fibrous web is too high, the mass of fibrous material provided in step S 1 can also be reduced.In one embodiment of the method, the mass flow of the fibrous material compacted in step S 3, and / or the mass of fibrous material contained in the flat fibrous web and / or the mass of fibrous material contained in the consolidated fibrous web is determined and taken into account in the regulation of at least one of steps S 1, S 3 and / or S 4. If the mass flow of the fibrous material compacted in step S 3 is too low, for example, an increased mass flow can be provided in step S 1, a lower compaction ratio and thus a lower compaction can be set or regulated in step S 3 and / or a higher mass of fibrous material can be detached from the compacted fibrous material, in particular from a compacted fibrous material mat, in step S 4. By reducing the compaction in step S 3, less fibrous material can be temporarily stored in the compaction device and thus, depending on the mass of fibrous material contained in the compaction device, at least temporarily more fibrous material can be fed from the compaction device to the method.In one embodiment of the method, at least one of steps S 3, S 4 and S 5 can be regulated in such a way that fluctuations in the mass flow of the fibrous material detached in step S 4 are attenuated. Damping of fluctuations can ideally mean a complete or nearly complete avoidance of fluctuations. In other words, fluctuations in the mass flow of the fibrous material are to be reduced or smoothed. If, for example, the mass flow of the fibrous material provided in step S 1 fluctuates, then by regulating steps S 3, S 4 and / or S 5, this fluctuation can be compensated or attenuated in such a way that the mass flow of the fibrous material detached in step S 4 remains constant, in particular according to a predefined value. In this respect, fluctuations in the "input" of the fibrous material into the compacting device can be regulated in such a way that they are not reflected in the "discharge". For example, the compression ratio may be controlled in step S 3. If the mass flow of the fibrous material provided in step S 1 increases, a larger compaction ratio can be regulated in step S 3, for example, so that more compaction is carried out and more fibrous material is temporarily stored. As a result, the mass flow of the fibrous material detached in step S 4 and thus of the "discharge" remains the same.In one embodiment of the method, at least the steps of the method S 1 to S 4 according to at least one of the embodiments described above are carried out continuously and / or repeatedly. For example, steps S 1 to S 4, steps S 1 to S 5 or S 1 to S 6 (with or without step S 5) of the method can be carried out continuously, and / or steps S 1 to S 4, S 1 to S 5 or S 1 to S 6 (with or without step S 5) can be carried out repeatedly. In a repeated execution, the obtained fibrous-material air volume flow from step S 4, S 5 or S 6 of a "first" pass can be the provided fibrous-material air volume flow from step S 1 of a "second" pass. Thus, for example, a plurality of compacting devices can be connected in series, which for example apply steps S1 to S4, S1 to S5 or S1 to S6 (including step S5) to the same fibrous material-air volume flow repeatedly one after the other, wherein the latter is enriched with fibrous material more and more and more and more and the fibrous material is defibered.In one embodiment of the method, the separation of the fibrous material in step S 2 is carried out by means of a cyclone separator or a screen or a rotating drum screen, which is suitable in particular for separating fibrous material fibers from a fibrous material-air volume flow. A cyclone separator has in particular the advantage of a high energy efficiency and a low energy consumption associated therewith due to passive mode of operation. In addition, a small installation space can likewise be achieved by using a cyclone separator. This can be a decisive advantage, for example, in the case of a vertical arrangement of the compacting device.In addition, a cyclone separator is particularly well suited for separating small amounts of fibers at very high volume flows in a short separation time. In addition, the cyclone separator has a very low tendency to dirt, for example a very low tendency to fiber deposit.In one embodiment of the method, the fibrous material is compacted in the compacting device, in particular in a volume of the compacting device using gravity, and / or on account of an, in particular continuous, volume reduction with simultaneous venting of the fibrous material, and / or within a tapering compacting shaft at least partially forming the volume. In this respect, the compacting can already take place using the force of gravity in that further fibrous material is applied continuously to a first quantity of fibrous material and is compacted in the process by the force of gravity of the mass of the further fibrous material. A tapering compression shaft can have, for example, two or more side walls which converge continuously, wherein the cross section of the compression shaft is continuously reduced in particular in the direction of gravity.The side walls can be air-permeable in particular so that air still contained therein can escape during the compaction of the fibrous material.In one embodiment, the compacting device can be designed for compacting the fibrous material into a fibrous material mat. The compressed fibrous material from step S 3 can be compressed, in particular within a volume of the compacting device, for example, to such an extent that a fibrous material mat is formed. A fibrous mat can be designed, for example, as endless, contain a certain thickness, width and density and be designed as self-supporting. However, it is also possible for the compressed fibrous material from step S 3 to be compressed only to such an extent that the fibrous material is compressed but not self-supporting, that is to say holding its shape.For example, the fibrous mat formed self-supporting or non-self-supporting with the compacting device can have a density of 10 kg / m 3 to 200 kg / m 3, in particular of 30 kg / m 3 to 150 kg / m 3, preferably of 50 kg / m 3 to 100 kg / m 3, particularly preferably of 60 kg / m 3 to 70 kg / m 3.The fibrous mat ideally has a defined, adjustable thickness of greater than or equal to 0.005 m and less than or equal to 0.20 m, in particular greater than or equal to 0.01 m, in particular less than or equal to 0.15 m, preferably less than or equal to 0.10 m, particularly preferably less than or equal to 0.05 m.The fibrous mat ideally has a defined width in the transverse direction CD of greater than or equal to 0.20 m and less than or equal to 2.7 m, in particular of less than or equal to 1.5 m, preferably of less than or equal to 1.0 m, particularly preferably of less than or equal to 0.8 m. Advantageously, the width of the fibrous mat is matched to the subsequent detachment device, in particular, when using a second defibering device, is matched to the maximum axial extent of the defibering agent, wherein here a simpler adaptation of the defibering device, for example the housing, which is supplied for the most part, can be adopted without deep-lasting adaptations.The fibrous mat can be transported for detachment at a (feed) speed of greater than or equal to 1 m / min to less than or equal to 15 m / min, in particular of less than or equal to 10 m / min, preferably of less than or equal to 5 m / min, particularly preferably of less than or equal to 3.5 m / min.In a further aspect, in order to achieve the object, a device for producing a fibrous web, in particular a tissue, paper or board web or a nonwoven web, is proposed, comprising: a) a raw material processing plant for the low-water processing of pulp-containing fibers to form individual fibers and / or fiber bundles; b) a dry forming device for dry forming the individual fibers and / or fiber bundles in an air stream to form a flat fiber web on a forming belt; c) an application device for applying a fluid, in particular water and / or a water-additive mixture, to the fiber web; d) a consolidation device for consolidating the flat fiber web by applying pressure and / or temperature in a press nip;The device is designed to carry out at least one embodiment of the method described above, and has a separator for separating fibrous material from a fibrous material-air volume flow and a compacting device for compacting fibrous material, in particular for compacting fibrous material to form a fibrous material mat. According to the invention, the device is characterized by the characterizing part of claim 14.The advantageous refinements which have been described above for the method according to the invention also apply analogously to the device according to the invention.The compacting device can be arranged, for example, on a fiberizing device, for example a hammer mill. This defibering device can be, for example, the defibering device used in step S 6 of the method. The arrangement of the compacting device on a defibrating device can be advantageous in particular because both the compacting device and the defibrating device can be designed with a suitable width corresponding to the required production capacity of the device. Thus, the production of the fiber web is independent of the dimensions of the starting material, i.e. for example the dimensions of the cellulose bales.In one embodiment of the device, the latter can have a detachment device for detaching, in particular beating off, the fibrous material compacted by the compacting device, wherein the detachment device is in particular designed as a comminution device and / or defibering device, in particular as a beating roller or as a hammer mill. It is likewise possible for a detachment device to have another suitable operating principle, such as in particular a pneumatic operating principle, and to detach the compressed fibrous material by means of compressed air, for example by means of a supplied air stream.The term "low-water" processing of pulp-containing fibers to individual fibers and / or fiber bundles also encompasses, in the context of the present invention, the processing of the raw material completely without targeted feeding of water and / or other liquids. Here, a "low-water" raw material treatment is to be understood as meaning that the amount of water already contained in the provided, air-dry raw material can be sufficient for the raw material treatment process and the treatment process can be carried out without further addition of water or moisture. The water content of the air-dry raw material is usually 1% to 30%, in particular 1% to 20%, in particular between 1% to 10%, based on the mass of the raw material.Alternatively, in the case of "low-water" processing, it can also be provided that a small amount of water or moisture is contributed to the raw material in the processing process, such that the water content of the raw material or of the chips and / or of the individual fibers in the individual processing steps does not exceed an upper limit of at most 30%, in particular 20%, in particular 10%, based on the mass of the raw material, of the chips or of the individual fibers. It should be taken into account that the raw material can absorb water or moisture from its environment in the case of storage for at least several hours, wherein this maximum amount depends on the raw material, the storage conditions and the environmental conditions.The invention expressly also extends to such embodiments which are not given by combinations of features from explicit references back to the claims, whereby the disclosed features of the invention can be combined with one another as desired, insofar as this is technically expedient.For differentiation between the fibrous webs produced, for example a tissue, paper or board web on the one hand or a nonwoven web (in English "nonwoven") on the other hand, the following distinction is made which is based on the fiber length, density and type of fiber bonding: a tissue, paper or board web is understood to mean a fibrous web having predominantly average fiber lengths which are shorter than the fiber lengths of nonwoven webs, of less than or equal to 5 mm, in particular less than or equal to 4 mm, in particular less than or equal to 3 mm, a predominant bond by hydrogen bonds and a bulk density of greater than or equal to 0.4 g / cm 3. The fibers used in a tissue, paper or board web are additionally distinguished in that they have a slenderness ratio of fiber length to fiber diameter of less than or equal to 200, in particular less than or equal to 150, in particular less than or equal to 100.A nonwoven web, which likewise consists mainly of fibers, is understood as a substantial delimitation from a tissue, paper or board web to mean that the nonwoven web has a fiber content of at least 30% of very long fibers having an average fiber length of more than 5 mm or even continuous fibers which determine the nonwoven character. In the case of a nonwoven web, the aspect ratio of fiber length to fiber diameter of the fibers of greater than or equal to 300 is also sought. The remaining fibre content of a nonwoven web can be composed differently and the bulk density should be below 0.40 g / cm 3 in order to add a fibrous web to the nonwoven webs.Further features and advantages of the invention will become apparent from the following description of a preferred exemplary embodiment with reference to the drawing.Exemplary embodiments of the present invention are illustrated below with reference to purely schematic drawings. The following shows: FIG. 1 schematically shows a first exemplary embodiment of a method according to the invention for producing a dry-laid fibrous web 309; FIG. 2 schematically shows a second exemplary embodiment of a method according to the invention for producing a dry-laid fibrous web 309: FIG. 3 shows a schematic illustration of a raw material processing plant 2 for the low-water processing of fibrous material 209; and FIG. 4 shows a schematic illustration of a fibrous web plant 3 for producing a dry-laid fibrous web 309.The same reference numerals are used in all figures for the same or technically identical components and components. FIGS. 1 and 2 are limited to the representation of method steps, wherein the reference numerals of elements of the device shown in FIGS. 3 and 5 are also mentioned in this connection in the description.FIG. 1 schematically shows a first exemplary embodiment of a method for producing a dry-laid fibrous web 309. In a first step, bale pulp or pulp-containing fibers 200 are provided. The fibrous material is comminuted and subsequently stacked. The comminution can take place, for example, within a comminution device 221. Here, stacking is an optional step.Subsequently, the fibrous material 201 is conveyed to a first defibering device 222 and defibered there. This defibering is also referred to as "defibering stage one", which can be designed such that only the first part of the defibering work is carried out therein and, depending on the design, possible tooth sets of the defibering device 222 can be designed roughly. The pulp 201 fed to this defibrating device 222 contains, for example, a greater proportion of nodes and fiber bundles, which are largely dissolved in the defibrating device 222. The fibrous material 205 thus defibered is then provided by means of an air flow 90 in the form of a fibrous material air volume flow in the sense of step S 1 of the proposed method.The fibrous material 205 is subsequently separated in step S 2 from this fibrous material air volume flow 205B, for example by means of a separator 252, which can be designed as a cyclone separator. Subsequently, the fibrous material 205 is further fed in step S 2 to a compacting device 250 or is collected in the volume of a compacting device 250. Subsequently, the fibrous material 205 is compacted in the volume of the compacting device 250 according to step S 3 before it is refibered in a second fiberizing device 223. The air of the fibrous material air volume flow 205B provided in step S 1 can be discharged through a so-called air bypass (not shown) during the separation in step S 2. In step S 4, it can then be fed again to the previously compressed fibrous material 205 from step S 3 as an air stream 90, for example, in order to obtain a fibrous material-air volume stream again (step S 5). The detachment in step S 4 can also take place directly by supplying the air as directed air flow 90 from the air bypass. It is also possible for the fibrous material 205 compressed in step S 3 to be detached directly into or by the second defibering device 223. Detachment can mean, for example, that the fibrous material 205 is detached from a fibrous material composite, such as in particular a fibrous material mat, provided that the fibrous material 205 has been compacted in the compacting device 250 to form a fibrous material mat. This defibering is also referred to as "defibering stage two" and may be designed for the final quality of the defibering. This two-stage embodiment of the fiberizing can be advantageous because of a reduced energy requirement with the same overall size of the fiberizing device and because of an improved quality of the fiberizing. Finally, the fibrous material 205 can be laid by a dry forming device 4 and, after the production of the dry laid fibrous material web 309, can be rolled up in the fibrous material web plant 3 by the rolling-up 12.As can be seen from FIG. 1, a sensor 62 can determine the fill level of the fibrous material 205 or the mass of fibrous material 205 in the volume of the compacting device 250 and various regulating or control steps can be carried out on the basis of this value. For example, the mass flow of fibrous material 205 of the fibrous material air volume flow 205B provided in step S 1 can be changed, for example by already influencing the conveying of the fibrous material 205. If, for example, the mass of fibrous material 205 in the compacting device 250 is particularly large, the conveying of the fibrous material 205 to the compacting device 250 can be reduced or slowed down.Similarly, a sensor 64 can determine the thickness and / or the mass flow of the fibrous material 205 of the fibrous material compacted in step S 3 and various control steps can be carried out on the basis of this value. For example, the compaction of the fibrous material 205 in step S 3, in particular the compaction ratio of the compaction in step S 3, can be regulated. The mass flow of the fibrous material 205 provided in step S 1 can likewise be regulated.Furthermore, a measuring device 61 or a density sensor 63 can determine the density and / or the mass of fibrous material of the dry laid flat fibrous material laid scrim 300 or of the consolidated fibrous material web 309, and various regulating or control steps can be carried out on the basis of this value. For example, the mass flow of the fibrous material 205 in the fibrous material air volume flow 205B provided in step S 1 can be regulated, and / or the compaction of the fibrous material 205 in step S 3 and / or the mass flow of the fibrous material 205 detached in step S 4.FIG. 2 schematically shows a second exemplary embodiment of a method for producing a dry-laid fibrous web 309. The second embodiment is substantially identical to the first embodiment, and therefore reference is made to the corresponding description. The second exemplary embodiment shown in FIG. 2 differs from the first exemplary embodiment in that the step S 4 for detaching the compacted fibrous material 205 in the form of a beating is carried out between the compaction in the compaction apparatus 250 and the second defibering stage 223. The compressed fibrous material 205 from step S 3 can be compressed, for example, to such an extent that a fibrous material mat is formed. A fibrous mat can be designed, for example, to be endless, have a certain thickness and density and be designed to be self-supporting. Detachment or beating of the fibrous material 205 can then be understood to mean that fibers 205 or fiber bundles 205 are detached or beaten again from the compacted fibrous material 205 from step S 3 in particular at a predetermined mass per unit time in order to obtain a predetermined mass flow of fibrous material 205. For example, a knocking-off device can be provided for this purpose, which in particular releases individual fibers 205 or fiber bundles 205 from a fibrous mat compacted in the previous step S 3.FIG. 3 shows a schematic illustration of a raw material processing plant 2 for the low-water processing of fibrous material 209, which can produce the fibrous material 209, for example from fibrous recycled material and / or from virgin fibrous material, in particular as bale material 200, by comminution devices 221, 222, 223 and / or fiberizing devices 222, 223. After successful comminution or fiberization, the fibrous material 209 can be transported in a substantially constant mass flow in an air flow 90 to a fibrous material web installation 3. Specifically, the fibrous material-air volume flow 207 and thus the treated fibrous material 209 can be fed into a continuous mass flow via a distribution channel or a plurality of distribution channels of at least one of the dry forming devices 4A, 4B, 4C shown in FIG. 4 of a fibrous material web plant 3 for producing a dry formed fibrous material web 309. A coupling of the two production processes of the low-water raw material treatment 2 and the fibrous web plant 3 is an advantageous component for the production of high-quality fibrous webs 309, which can both be matched or controlled and / or regulated to one another via a superordinate control and / or regulating device 60.To clarify the individual directions, a superordinate, Cartesian coordinate system is set up in FIGS. 3 and 4. The x direction corresponds to an extension in the longitudinal direction, which is also referred to as machine direction MD (machine direction). The y direction corresponds to a direction orthogonal to the machine direction MD. It is also referred to as cross-direction (CD). The z-direction, on the other hand, corresponds to the height direction.The low-water raw material processing process or the raw material processing plant 2 can be distinguished by multistage comminution of the discontinuously fed raw material, wherein at the end of the low-water raw material processing process 2 a fibrous material-air volume flow matched to the downstream fibrous material web plant 3 and having fibrous material 209 distributed therein can be provided in particular continuously.The term raw material is used here for pulp-containing fibers 209, in particular virgin fiber pulp from bale goods 200 and / or recycling fibers. For example, a bale 200 of virgin pulp 209 may consist of a plurality of stacked pulp sheets 200. This pulp may be NBSK pulp, as is usually used for the production of a paper, board or tissue web by wet process. The raw material discontinuously supplied to the method is usually supplied as bale goods 200 via a conveyor belt 220 to a first comminution device 221. In this case, the first comminution device 221, in particular a first shredder 221, can be designed in such a way that it can carry out a first comminution of the bale product 200 into coarse chips, chips or chips 201.The chips 201 can then be supplied to a cleaning device 230, wherein any unwanted constituents still contained in the chips 201, so-called "rejects", such as metals, contaminants and / or packaging residues, can be filtered out. The chips 201 are present after the cleaning device 230, which can be designed, for example, as a cyclone separator, as cleaned chips 202. These cleaned chips 202 are then typically temporarily stored in a larger memory 240, which can be embodied in particular as a silo. Optionally, after cleaning the chips 201 and before the memory 240 for the cleaned chips 202, a conditioning device 260 or conditioning can be provided. In this case, the conditioning can supply a small amount of moisture to the cleaned chips 202, for example in order to minimize or avoid dust formation and / or electrostatic charging.The memory 240 may be implemented as a vertical memory silo 240, wherein the cleaned chips 202 may be easily compressed by their own weight. Furthermore, at least one discharge device 241 can be provided in the storage device 240, which can enable continuous discharge of the cleaned chips 202. To assist the discharge of the cleaned chips 202 from the storage device 240, a first air stream 90 can be mixed directly at the outlet of the storage device 240, so that the cleaned chips 202 can be distributed and mixed in the first air stream 90 and can thus be transported very easily to the second comminution device 222.The second comminution device 222 or first comminution device 222 is designed, for example, as a hammer mill, wherein the cleaned chips 202 can be comminuted or defibrated there in particular until individual fibers with isolated nodes 205 form, which can then pass a filter device arranged in the second comminution device 222. By supplying an air stream 90 downstream of the second comminution device 222, the discharge of the individual fibers 205 from the second comminution device 222 can be assisted and the further transport to the next processing station can be carried out. The individual fibers with individualized nodes 205 are in this case highly resolved in the supplied air stream 90.The fibrous material 205 thus defibered can then be provided in the form of a fibrous-material-air volume flow 205B in the sense of step S 1. The fibrous material 205 can then be separated by a separator 252 in the sense of step S 2 and fed to a compacting device 250. In the compacting device 250, the fibrous material 205 is compacted according to step S 3, for example to form a fibrous material mat, not shown. Subsequently, the fibrous material 209 compressed in step S 3 is detached from the fibrous material mat and transferred, for example, to a high-resolution, continuous mass flow in the form of a fibrous material-air volume flow 207.The high-resolution, continuous fibrous material-air volume flow 207 is supplied directly to the third comminution device 223 or second comminution device 223, which can likewise be designed as a hammer mill. The third comminution device 223 comminutions or defibers the high-resolution, continuous mass flow of the fiber-air mixture 207 until essentially only individual fibers 208 are still present, preferably free of nodes or only with a small proportion of nodes, which can then pass in particular through a filter device arranged in the third comminution device 223. For a further reduction of the individual fiber concentration in the fibrous material air volume flow 207, a further air flow 90 can subsequently be added before the high-resolution individual fibers 209, substantially free of nodes, are exactly dosed and continuously supplied to the fibrous material web plant 3 via a distribution system or distribution channels.In the exemplary embodiment of FIG. 4, in particular three dry forming devices 4A, 4B, 4C are arranged one behind the other in order to be able to produce three layers of the fibrous web 309 that are layered one above the other.The fibrous material 209 transported with the fibrous material-air volume flow 207 can be further guided to at least one of the dry forming devices 4A, 4B, 4C of the fibrous material web installation 3 and in particular distributed as uniformly as possible transversely to the machine direction MD or in the transverse direction CD of the fibrous material web installation 3. After the dry forming devices 4A, 4B, 4C, at least one application device 7 can be provided, which can apply or apply a fluid, in particular water or a water-additive mixture, to the planar laid fiber scrim 300 or the consolidated laid fiber scrim 305. Furthermore, at least one consolidation device 8 can be provided after the dry-forming devices 4A, 4B, 4C, which consolidation device can consolidate the fibre laid scrim 300, in particular by applying pressure and / or temperature, for example in at least one press nip. In this case, the laid fiber fabric 300 or the fiber web 305, 309 can also be provided with a structure.The dry forming step in at least one of the dry forming devices 4A, 4B, 4C can be controlled and / or regulated by at least one included control and / or regulating means, wherein the fibrous material 209 can be deposited in the dry forming devices 4A, 4B, 4C, in particular partially with the aid of gravity, on an in particular revolving, in particular permeable forming belt 40 and can form an in particular still substantially unsolidified planar fibrous material 300. Furthermore, the dry forming devices 4A, 4B, 4C can each comprise at least one suction device 30, which can assist the deposition of the individual fibers 209 on the permeable forming belt 40, in particular can also influence them as control and / or regulating means.In particular, the fiber laid scrim 300 can be measured with respect to its mass distribution by at least one measuring device 61, in particular a mass measuring device 61 extending in the cross-machine direction CD, wherein the measurement signal can act as a control variable, in particular via the higher-order control and / or regulating device 60, on the feeding of the fibrous material 209 from the raw material processing plant 2 and / or on the suction device 30 and / or on the compacting device 250. Optionally, at least one moisture measuring device and / or one measuring device for monitoring the fluid application can be present.After passing through the first press nip 83, the laid fiber web 300 on the transporting strand of the forming belt 40 can be transported to a transfer region 100. A plurality of vacuum boxes 31, 32 or other vacuum means can be arranged in the screen loop of the press belt 41 behind the first press belt deflection roller, in particular in order to continue the transfer of the laid fiber web 300 over the entire length of the transfer region 100 and also to keep the laid fiber web hanging overhead on the transporting strand of the press belt 41 after the transfer region 100. At the end of the transporting strand of the press belt 41, the laid fiber web 300 which has meanwhile been strengthened by the second press nip 80 can be transferred from the press belt 41 to a connecting belt 102 in a further transfer region. After passing through the second press nip 80, the laid fiber web 300 is transported to the further transfer region suspended overhead on the transporting strand of the press belt 41. The further transfer region can serve to transfer the laid fiber fabric 300 from the press belt 41 to the connecting belt 102.With the connecting belt 102, the laid fiber fabric 300 can be guided from the press belt 41 to just before the third press nip 84. In the third press nip 84, the laid fiber web 300 can be further consolidated by pressure and / or temperature before it can be guided further to the dryer apparatus 10 as consolidated laid fiber web 305. After leaving the third press nip 84, the consolidated laid fiber web 305 can be picked up in a transfer region by a transfer belt 103 in order to transfer the consolidated laid fiber web 305 to the dryer screen 42.To complete the continuously produced fibrous web 309, a web-wide roll-up 12 can be arranged at the end of the fibrous web plant 3. Furthermore, a dryer device 10 can be arranged in the fibrous web plant 3. In this case, the at least one dryer device 10 can be arranged downstream of the application devices 7 in order to dry a fibrous web 309 to which a fluid has been applied.List of reference numbers:1 Apparatus 2 Raw material processing plant 3 Fibrous web plant 4A, 4B, 4C Dry forming apparatus 7 Application apparatus 8 Consolidation apparatus 10 Dryer apparatus 11 Pre-dryer apparatus 12 Reeling 22 Running direction 30 Suction apparatus of the dry forming apparatus 31 Vacuum box - application apparatus 32 Vacuum boxes 39A, 39B, 39C Sucked-off air 40 Support element, forming belt 41 Support element, press belt 42 Support element, Drying wire 60 Control and / or regulating device 61 Measuring device 62 Fill level sensor Compacting device 63 Density sensor Fibrous web 64 Thickness sensor Fibrous mat 71-73 Application devices 80 Second press nip 81 Press roller 82 Press element 83 First press nip 84 Third press nip 90 Air stream 100 Transfer region 102 Connecting belt 103 Transfer belt 104 First deflection roller (of the transfer belt) 105 Deflection roller (of the transfer belt) 110 Suction opening (of the pre-dryer device) 200 Pulp-containing fibers (bale product) 201 Comminuted bale product, Snipsel "chips" 202 Cleaned chips 205 Individual fibers with individualized nodes or chopped chips 205B Individual fibers with individualized nodes or chopped chips, High-resolution mass flow of fibrous material dissolved in a fiber-air mixture 207 in a fiber-air mixture 208 single fibers substantially free of nodes 209 fibrous material in the form of single fibers and / or fiber bundles 220 conveyor belt 221 first comminution device (shredder) 222 second comminution device, in particular first comminution device 223 third comminution device, in particular second comminution device 230 cleaning device 240 storage 241 discharge device 250 compacting device 252 separator 260 conditioning device 300 fiber lay after dry forming device 305 consolidated fiber lay 309 fibrous material web MD machine direction CD machine transverse direction z vertical direction

Claims

Method for producing a dry laid fibrous web (309), in particular a tissue, paper or board web or a nonwoven web, comprising the following steps: a) raw material processing of pulp-containing fibers (200) to form individual fibers and / or fiber bundles (209); b) forming the individual fibers and / or fiber bundles (209) in a fibrous material-air volume flow to form a flat fiber web (300), in particular on a forming belt (40) by a dry forming method; c) consolidating the flat fiber web (300) to produce a fibrous web (309), in particular by applying pressure and / or temperature in at least one press nip (80, 83, 84); wherein step a) comprises the following further steps: S1 providing a fibrous-air volume flow (205B), S2 separating the fibrous material (209) from the provided fibrous-air volume flow (205B) and feeding the fibrous material (209) into a compacting device (250), S3 compacting the fibrous material (209) in the compacting device (250), S4 detaching, in particular knocking, the fibrous material (209) compacted in step S3, characterized in that it comprises the following further step: S0 determining the mass flow of the fibrous material (209) of the fibrous-air volume flow (205B) provided in step S1.Method according to the preceding claim, characterized in that it comprises the following further step: S5 supplying an air stream (90) to the detached fibrous material (209) in order to form a fibrous material-air volume stream (207) with in particular constant mass flow of fibrous material (209).Method according to the preceding claim, characterized in that the air separated in step S2 is supplied in step S5 at least partially as an air stream (90) for forming the fibrous-material-air volume stream (207), wherein in particular only the air separated in step S2 is supplied.Method according to at least one of the preceding claims, characterized in that it comprises the following further step: S6 supplying the detached fibrous material (209) or a formed fibrous material-air volume flow (207) to a defibering device (223).Method according to at least one of the preceding claims, characterized in that, in order to obtain a predetermined mass flow of fibrous material (209) detached in step S4, at least one of the following variables is regulated: - the mass flow of the fibrous material (209) of the fibrous material-air volume flow (205B) provided in step S1, - the compaction ratio of the compaction in step S3, and / or - the mass flow of the fibrous material (209) detached in step S4.Method according to the preceding claim, characterized in that the determined mass flow of the fibrous material (209) of the fibrous material-air volume flow (205B) provided in step S1 and / or a predetermined mass flow of the fibrous material (209) detached in step S4 which results in particular from a method step downstream of the raw material treatment is taken into account in the regulation of at least one of steps S3, S4 and / or S5.Method according to at least one of the preceding claims, characterized in that the mass of fibrous material (209) contained in the compacting device (250) is determined and taken into account in the regulation of the mass flow of the fibrous material (209) of the provided fibrous material-air volume flow (205B) in step S1, and / or the mass of fibrous material (209) contained in the flat fibre web (300) is determined and taken into account in the regulation of the mass flow of the fibrous material (209) of the provided fibrous material-air volume flow (205B) in step S1, and / or the mass of fibrous material (209) contained in the consolidated fibrous material web (309) is determined and taken into account in the regulation of the mass flow of the fibrous material (209) of the provided fibrous material air volume flow (205B) in step S1.Method according to at least one of the preceding claims, characterized in that the mass flow of the fibrous material (209) compacted in step S3 and / or the mass of fibrous material (209) contained in the flat fibre laid scrim (300) and / or the mass of fibrous material (209) contained in the consolidated fibrous material web (309) is determined and taken into account in the regulation of at least one of steps S1, S3 and / or S4.Method according to at least one of the preceding claims, characterized in that at least one of the steps S3, S4 and S5 is regulated in such a way that fluctuations in the mass flow of the fibrous material (209) detached in step S4 are attenuated, in particular that fluctuations of at most 4% of the mass flow of the fibrous material, preferably fluctuations of at most 2% of the mass flow of the fibrous material, are achieved.Method according to at least one of the preceding claims, characterized in that at least steps S1 to S4 of the method according to at least one of the preceding claims are carried out continuously and / or repeatedly.Method according to at least one of the preceding claims, characterized in that the separation of the fibrous material (209) in step S2 is carried out by means of a cyclone separator (252).Method according to at least one of the preceding claims, characterized in that the compaction of the fibrous material (209) in the compaction device (250) takes place using the force of gravity, and / or takes place on the basis of an, in particular steady, volume reduction with simultaneous venting of the fibrous material (209), and / or takes place within a tapering compaction shaft.Method according to at least one of the preceding claims, characterized in that the compacting device (250) is designed for compacting the fibrous material (209) to form a fibrous material mat.Device (1) for producing a fibrous web (309), in particular a tissue, paper or board web or a nonwoven web, comprising: a) a raw material processing plant (2) for the low-water processing of pulp-containing fibers (200) to individual fibers and / or fiber bundles (209); b) a dry forming device (4) for dry forming the individual fibers and / or fiber bundles (209) in an air stream (90) to form a flat fiber web (300) on a forming belt (40); c) an application device (71) for applying a fluid, in particular water and / or a water-additive mixture, to the fiber web (300); d) a consolidation apparatus (8) for consolidating the flat fibre laid scrim (300) by applying pressure and / or temperature in a press nip (80, 83, 84); wherein the apparatus (1) is designed to carry out the method according to at least one of the preceding claims, wherein the apparatus (1) has a separator (252) for separating fibrous material (209) from a fibrous material-air volume flow (205B) and a compacting apparatus (250) for compacting fibrous material (209), in particular for compacting fibrous material (209) to form a fibrous material mat, characterized in that in step S0 a means for determining the mass flow of the fibrous material (209) of the fibrous material-air volume flow (205B) provided in step S1 is provided.Device (1) according to the preceding claim, characterized in that the device (1) comprises a detachment device for detaching, in particular beating off, the fibrous material compacted by the compacting device, wherein the detachment device is in particular designed as a comminution device (223) and / or a defibration device (223), in particular as a beating roll or as a hammer mill (223).

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