Method and device for processing a fibrous web, comprising a pressing zone and an adjoining heating zone

Abstract

The invention relates to a method for processing a fibrous web (2), in which method the fibrous web (2) is applied to a first continuous metal strip (3) or to a textile substrate (5) resting on the first metal strip (3). The fibrous web (2) is transported, by means of the first metal strip (3), through a pressing zone (Z1) in which the fibrous web (2) is mechanically dried. Subsequently, the fibrous web (2) is transported, by means of the first by means of a second metal strip (3, 20), through a heating zone (Z2) in which the fibrous web (2) is thermally dried. The time it takes for the fibrous web (2) to pass through the heating zone (Z2) is in the range of 1.1 to 11 s. The invention also relates to a device (1a..1c) for carrying out the method according to the invention.

Description

[0001] Method and device for processing a fiber web with a pressing zone and a subsequent heating zone

[0002] The invention relates to a method for processing a fibrous web (in particular a cellulose-containing fibrous web), in which the fibrous web is applied to a first endless metal belt which is guided over at least two deflection rollers, or to a textile carrier which rests on the first metal belt, the fibrous web is transported to a pressing zone with the aid of the first metal belt, the fibrous web is transported through the pressing zone with the aid of the first metal belt and the fibrous web is mechanically dried in the pressing zone, wherein pressure is exerted on the fibrous web in the pressing zone with the aid of a pressing device, the fibrous web is dried with the aid of the first metal belt or with the aid of a second metal belt onto which the fibrous web or the textile carrier is transferred,is transported to a heating zone and in which the fibrous web is transported through the heating zone with the aid of the first metal belt or second metal belt, wherein the fibrous web is dried thermally (and without pressure) in the heating zone, wherein the first metal belt or second metal belt leading through the heating zone is heated and / or an air stream acting on the fibrous web in the heating zone is heated.

[0003] Furthermore, the invention relates to a device for processing a fibrous web (in particular a cellulose-containing fibrous web), comprising a first endless metal belt which is guided over at least two deflection rollers and which is designed to receive the fibrous web or a textile carrier for the fibrous web, a pressing zone to and through which the first metal belt leads, wherein the pressing zone comprises a pressing device which is designed for the mechanical drying of the fibrous web, and a heating zone, wherein a) the first metal belt leads to and through the heating zone or b) the device comprises a second metal belt which is designed toto take over the fibrous web or the textile carrier from the first metal belt and which leads to and through the heating zone, and wherein the heating zone is designed for thermally drying the fibrous web (without applying a pressing pressure) and comprises a heater for heating the first or second metal belt leading through the heating zone and / or for heating an air flow acting on the fibrous web in the heating zone.

[0004] To produce a fibrous web, a slurry-like, fibrous pulp is mixed, pressed, and dried in several process steps to ultimately produce a fibrous web with a defined (relatively low) moisture content or (relatively high) dry matter content. For example, paper, cardboard, and other fibrous products can be manufactured in this way. In general, the production of fibrous webs is technically challenging. One reason for this is that, on the one hand, the drying process used to produce a fibrous web requires a lot of energy, and energy costs account for a significant proportion of the production costs of the fibrous web. On the other hand, there is demand for large quantities of fibrous webs, and therefore the price should be as low as possible. This tension has been exacerbated by the recent sharp rise in energy costs.An additional problem is the constantly increasing quality requirements for the fibrous web.

[0005] An object of the invention is therefore to provide an improved method for processing a fibrous web and an improved device for processing a fibrous web. In particular, the energy consumption and thus the costs for producing a fibrous web are to be kept low while maintaining high product quality.

[0006] The object of the invention is achieved by a method of the type mentioned above, in which the passage time of the fibrous web through the heating zone is in a range of 1.1 s to 11 s. In particular, the passage time of the fibrous web through the heating zone can be maintained in a range of 1.1 s to 11 s by a speed control for regulating the belt speed of the metal belt passing through the heating zone.

[0007] The object of the invention is further achieved with a device of the type mentioned at the outset, which additionally comprises a speed control for regulating a belt speed of the first or second metal belt leading through the heating zone, which is designed to effect a passage time of the fibrous web through the heating zone in a range from 1.1 s to 11 s. For example, a contact time of the fibrous web or the textile carrier with the heated metal belt can be in a range from 1.1 s to 11 s. In particular, the contact time of the fibrous web or the textile carrier with the heated metal belt can be kept in a range from 1.1 s to 11 s by the speed control for regulating a belt speed of the metal belt leading through the heating zone.

[0008] The proposed measures achieve good drying efficiency with comparatively low energy consumption, which also helps keep the costs of the produced fibrous web low. At the same time, a high-quality fibrous web is obtained. Common methods for drying fibrous webs, on the other hand, rely on high energy input with a short exposure time. This means that on the one hand the total amount of energy required for the drying process is comparatively high (particularly due to high thermal losses), but on the other hand the product quality is negatively affected by the heat generated during drying. Instead, it is proposed to divide the drying process into a particularly energy-efficient pressing step and subsequent thermal drying.

[0009] Especially when a single metal belt passes through the pressing zone and the heating zone, heating of the metal belt in the pressing zone cannot be ruled out, although the metal belt temperature is not a primary concern in the pressing zone. However, it is advantageous to preheat the fibrous web in the pressing zone to further improve the drying process in the heating zone.

[0010] Advantageously, the dry content of the fibrous web before the pressing zone is in the range of 20 to 50%. This allows for drying of the fibrous web through pressing and subsequent thermal drying in a particularly energy-efficient manner.

[0011] Further advantageous embodiments and developments of the invention emerge from the subclaims and from the description in conjunction with the figures.

[0012] It is advantageous if the fibrous web is lifted from the metal belt or textile carrier after the heating zone by a lifting device. For example, the lifting device can be formed by or encompass a wedge for lifting the fibrous web or textile carrier. In this way, the fibrous web can be easily transferred to other parts of a factory for the production of the fibrous web. The metal belt or textile carrier can therefore be kept comparatively short. If a textile carrier is used, two different cases are conceivable. On the one hand, the fibrous web can be lifted from the textile carrier and transported on its own; on the other hand, it is also conceivable for the fibrous web to be lifted from the metal belt together with the textile carrier, which may facilitate the further transport of the fibrous web.

[0013] It is advantageous if the temperature of the metal strip in the heating zone is in a range from 35 °C to 200 °C and / or if the temperature of the air flow in the heating zone is in a range from 40 °C to 650 °C. In particular, the proposed device can have a heating control that maintains the temperature of the metal strip in the heating zone in a range from 35 °C to 200 °C and / or that maintains the temperature of the air flow in the heating zone in a range from 40 °C to 650 °C. These parameters have proven particularly advantageous for drying the fibrous web in a gentle manner with low energy consumption.

[0014] It is advantageous if the pressing device has an endless press belt that is guided over at least two deflection rollers and / or at least one press roller and / or a press beam, wherein the pressing device is pressed against the first metal belt. The proposed options represent proven technical means for mechanically drying the fibrous web, whereby the proposed drying device can be quickly put into practice and thus a very rapid response to the sharp rise in energy prices. The press roller enables a relatively narrow, linear press zone and thus high press pressures with comparatively low absolute forces. The same applies to the press beam, which can, however, be used for somewhat longer press zones. Finally, an endless press belt enables particularly long press zones in which the moisture contained in the fibrous web can be pressed out in a particularly gentle manner.Another advantage is that there is no friction between the fiber web and the press belt, which means that a particularly high product quality can be achieved.

[0015] Finally, it is particularly advantageous if the pressure exerted on the fibrous web by the pressing device is in a range of 1 MPa to 8 MPa. In particular, the pressure exerted by the pressing device on the fibrous web can be maintained in a range of 1 MPa to 8 MPa by pressure control of the proposed device. This allows the moisture content in the fibrous web to be significantly reduced without subjecting the fibrous web to excessive mechanical stress and risking damage. Furthermore, the energy required to dry the fibrous web is relatively low compared to other drying processes.

[0016] At this point, it is noted that the variants disclosed for the processing method and the resulting advantages also apply analogously to the device presented and vice versa.

[0017] For a better understanding of the invention, it is explained in more detail using the following figures.

[0018] They show in a highly simplified, schematic representation:

[0019] Fig. 1 is a schematic side view of a first device for processing a fibrous web;

[0020] Fig. 2 is a schematic side view of a device with a first and second metal band and

[0021] Fig. 3 like Fig. 1, but with press rollers instead of a press belt.

[0022] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or component designations, whereby the disclosure contained in the entire description can be applied mutatis mutandis to identical parts with identical reference symbols or component designations. Furthermore, the positional information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure and, in the event of a change in position, is to be applied mutatis mutandis to the new position.

[0023] Fig. 1 shows a schematic representation of a device 1a for processing a (in particular cellulose-containing) fibrous web 2. The device 1a comprises a first endless metal belt 3 which is guided over at least two deflection rollers 4a, 4b and which is designed to receive the fibrous web 2 or a textile carrier 5 for the fibrous web 2.

[0024] Furthermore, the device 1a comprises a pressing zone ZI, to and through which the first metal belt 3 leads. The pressing zone ZI comprises a pressing device 6a, which is designed for the mechanical drying of the fibrous web 2. In this example, the pressing device 6a has an endless pressing belt 7, which is guided over at least two deflection rollers 8a, 8b. In order to be able to maintain a pressing pressure p in the (entire) pressing zone ZI, the device 1a in the example shown comprises a pressure plate 9 for the first metal belt 3 and a pressure plate 10 for the pressing belt 7. In particular, the pressure p exerted by the pressing device 6a can be kept within a predeterminable range by a pressure control 11. It is advantageous if a pressure p exerted on the fibrous web 2 by the pressing device 6a lies in a range from 1 MPa to 8 MPa.This allows the moisture content in the fibrous web 2 to be significantly reduced without subjecting it to excessive mechanical stress and risking damage. In particular, the pressure p exerted by the pressing device 6a on the fibrous web 2 can be maintained within a range of 1 MPa to 8 MPa by a pressure control 11.

[0025] In addition, the device 1a comprises a heating zone Z2, which is arranged downstream of the pressing zone ZI, wherein the first metal belt 3 in this example leads to and through the heating zone Z2. The heating zone Z2 is designed for the thermal drying of the fibrous web 2 and, in this example, has a heater 12 for heating the first metal belt 3 leading through the heating zone Z2, as well as a heater 13 for heating an air flow L acting on the fibrous web 2 in the heating zone Z2. To generate the air flow L, a blower 14 is provided in Fig. 1, and to direct the air flow L, a hood 15 is provided in Fig. 1 in the heating zone Z2. In particular, a heating control 16 can be provided, which keeps the temperature of the first metal belt 3 in the heating zone Z2 within a predeterminable range and / or which keeps the temperature of the air flow L in the heating zone Z2 within a predeterminable range.It is advantageous if a temperature of the first metal belt 3 in the heating zone Z2 is in a range from 35 °C to 200 °C and / or if a temperature of the air flow L in the heating zone Z2 is in a range from 40 °C to 650 °C. These parameters have proven to be particularly advantageous for drying the fibrous web 2 in a way that is gentle on the material and uses little energy. In particular, the heating control 16 can thus be configured to keep the temperature of the first metal belt 3 in the heating zone Z2 in a range from 35 °C to 200 °C and / or to keep the temperature of the air flow L in the heating zone Z2 in a range from 40 °C to 650 °C. In the embodiment according to Fig. 1, both the first metal belt 3 and the air flow L are heated. However, it is also conceivable that only the metal belt 3 or only the air flow L is heated.In other words, it can be provided that either only the heater 12 is provided for heating the first metal belt 3 leading through the heating zone Z2 or only the heater 13 is provided for heating the air flow L acting on the fibrous web 2 in the heating zone Z2.

[0026] A passage time of the fibrous web 2 through the heating zone Z2 lies in a range from 1.1 s to 11 s. For this purpose, the device 1a comprises a speed control 17 for controlling a belt speed v of the first metal belt 3 leading through the heating zone Z2, which speed control is designed to effect a passage time of the fibrous web 2 through the heating zone Z2 in a range from 1.1 s to 11 s. In particular, a contact time of the fibrous web 2 or the textile carrier 5 with the heated first metal belt 3 can lie in a range from 1.1 s to 11 s. Accordingly, it is advantageous if the contact time of the fibrous web 2 or the textile carrier 5 with the heated first metal belt 3 is kept by the speed control 17 in a range from 1.1 s to 11 s.The contact time refers specifically to the time during which the fibrous web 2 or the textile carrier 5 is in contact with the section of the first metal strip 3 actively heated by the heater 12.

[0027] In Fig. 1, the length of the hood 15 corresponds to the length of the heater 12 or the length of the section of the first metal strip 3 actively heated by the heater 12. However, this is not a mandatory condition, but the lengths could also be different.

[0028] The speed control 17 for controlling the strip speed v of the first metal strip 3 passing through the heating zone ZI, the heating control 16 for controlling the temperature of the first metal strip 3 in the heating zone Z2 and / or for controlling the temperature of the air flow L in the heating zone Z2 and the pressure control 11 for controlling the pressure p exerted by the pressing device 6a can be part of a higher-level control 18 together or in part.

[0029] Finally, the device 1a comprises, downstream of the heating zone Z2, an optional lifting device 19 for lifting the fibrous web 2 from the metal belt 3 or from the textile carrier 5. For example, the lifting device 19 can be formed by a wedge or comprise it, as is the case in Fig. 1. With the aid of the lifting device 19, the fibrous web 2 can be easily transferred to other parts of a factory for the production of the fibrous web 2. The first metal belt 3 or the textile carrier 5 can therefore be kept comparatively short. If a textile carrier 5 is used, two different cases are conceivable. On the one hand, the fibrous web 2 can be lifted together with the textile carrier 5 from the first metal belt 3, as shown in Fig. 1. In this way, the further transport of the fibrous web 2 can be facilitated under certain circumstances.It would also be conceivable for the fibrous web 2 to be lifted from the textile carrier 5 and transported further on its own. A combination of the two options is also conceivable. For example, the fibrous web 2 can be lifted together with the textile carrier 5 from the first metal belt 3, and then the fibrous web 2 can be lifted from the textile carrier 5. It would also be possible for the fibrous web 2 to be lifted first from the textile carrier 5, and then the textile carrier 5 from the first metal belt 3. The simultaneous lifting of the fibrous web 2 from the textile carrier 5 and the textile carrier 5 from the first metal belt 3 is also possible.

[0030] In Fig. 1, the fibrous web 2 rests on the textile carrier 5 and the textile carrier 5 rests on the first metal belt 3. Deviating from the illustration in Fig. 1, it is also conceivable that the fibrous web 2 rests directly on the first metal belt 3 and the textile carrier 5 is therefore omitted.

[0031] Fig. 2 now shows a device 1b for processing a (in particular cellulose-containing) fibrous web 2, which is very similar to the device 1a shown in Fig. 1. In contrast, a second endless metal belt 20 is now provided, which is guided over at least two deflection rollers 21a, 21b and which is designed to take over the fibrous web 2 or the textile carrier 5 from the first metal belt 3 and which leads to and through the heating zone Z2. Accordingly, in the technical teaching disclosed in Fig. 1, the second metal belt 20 takes the place of the first metal belt 3 for the purposes of the heating zone Z2. The technical teaching disclosed above is thus also applicable to the second metal belt 20 with regard to the heating zone Z2. For example, the heater 12 relates to the second metal belt 20. The speed control 17 is designed to control the belt speed v of the second metal belt 20 leading through the heating zone Z2.In addition, it can of course also be configured to regulate the belt speed v of the first metal belt 3 passing through the pressing zone ZI. The heating control 16 can be configured to maintain the temperature of the second metal belt 20 in the heating zone Z2 within a predeterminable range, namely in particular within a range of 35 °C to 200 °C. Finally, the optional lifting device 19 relates to the lifting of the fibrous web 2 or the textile carrier 5 from the second metal belt 20. The remaining technical teaching disclosed in relation to Fig. 1 is applicable without restriction to Fig. 2.

[0032] A method for processing a (particularly cellulose-containing) fibrous web 2 can now comprise the following steps:

[0033] Applying the fibrous web 2 to a first endless metal belt 3, which is guided over at least two deflection rollers 4a, 4b, or to a textile carrier 5, which rests on the first metal belt 3,

[0034] Transporting the fibrous web 2 to a pressing zone ZI by means of the first metal belt 3,

[0035] Transporting the fibrous web 2 through the pressing zone ZI by means of the first metal belt 3 and mechanically drying the fibrous web 2 in the pressing zone ZI, in which pressure p is exerted on the fibrous web 2 by means of a pressing device 6a,

[0036] Transporting the fibrous web 2 to a heating zone Z2 by means of the first metal belt 3 or by means of a second metal belt 20, onto which the fibrous web 2 or the textile carrier 5 is transferred,

[0037] Transporting the fibrous web 2 through the heating zone Z2 with the aid of the first metal belt 3 or second metal belt 20 and thermally drying the fibrous web 2 in the heating zone Z2, wherein the first metal belt 3 or second metal belt 20 leading through the heating zone Z2 is heated and / or an air flow L acting on the fibrous web 2 in the heating zone Z2 is heated, characterized in that a passage time of the fibrous web 2 through the heating zone Z2 is in a range from 1.1 s to 11 s.

[0038] In general, it is advantageous if the dry content of the fibrous web 2 before the pressing zone ZI is in a range of 20 to 50%. This enables drying of the fibrous web 2 by pressing and subsequent thermal drying in a particularly energy-efficient manner. In Figs. 1 and 2, the pressing device 6a comprises an endless press belt 7. However, this is only one of several possibilities. It would also be conceivable, for example, for the pressing device 6b to have one or more press rollers 23, as is the case with the device 1c shown in Fig. 3. Except for the different design of the pressing device 6b, the device 1c shown in Fig. 3 is similar to the device 1a shown in Fig. 1. Furthermore, the use of a second metal belt 20 is also conceivable. Accordingly, the technical teaching disclosed in relation to Figs. 1 and 2 is also applicable mutatis mutandis to the device 1c.Furthermore, the use of other pressing devices 6a, 6b would also be conceivable, for example a pressing beam which is pressed against the first metal strip 3.

[0039] Finally, it should be noted that the scope of protection is determined by the patent claims. However, the description and drawings must be used to interpret the claims. Individual features or combinations of features from the various embodiments shown and described may represent independent inventive solutions. The problem underlying these independent inventive solutions can be derived from the description.

[0040] In particular, it is also noted that the devices depicted may in reality comprise more or fewer components than shown. In some cases, the depicted devices or their components may also be shown not to scale and / or enlarged and / or reduced in size.

[0041] Reference symbol list la..lc device

[0042] 2 Fiber

[0043] 3 first metal band

[0044] 4a, 4b pulley

[0045] 5 textile carrier

[0046] 6a, 6b Pressing device

[0047] 7 Press belt

[0048] 8a, 8b pulley

[0049] 9 Printing plate first metal band

[0050] 10 Pressure plate press belt

[0051] 11 Pressure control

[0052] 12 Heating for metal strip

[0053] 13 Heating for air flow

[0054] 14 blowers

[0055] 15 hood

[0056] 16 Heating control

[0057] 17 Speed ​​control for belt speed

[0058] 18 overarching regulation

[0059] 19 Lifting device / wedge

[0060] 20 second metal band

[0061] 21a, 22b pulley

[0062] 22 Press roll

[0063] P Press pressure v Belt speed

[0064] L Airflow

[0065] ZI Press Zone

[0066] Z2 heating zone

Claims

Patent claims 1. A method for processing a fibrous web (2), comprising the steps Applying the fibrous web (2) to a first endless metal belt (3) which is guided over at least two deflection rollers (4a, 4b), or to a textile carrier (5) which rests on the first metal belt (3), Transporting the fibrous web (2) to a pressing zone (ZI) by means of the first metal belt (3), Transporting the fibrous web (2) through the pressing zone (ZI) by means of the first metal belt (3) and mechanically drying the fibrous web (2) in the pressing zone (ZI), in which pressure (p) is exerted on the fibrous web (2) by means of a pressing device (6a, 6b), Transporting the fibrous web (2) to a heating zone (Z2) by means of the first metal belt (3) or by means of a second metal belt (20) onto which the fibrous web (2) or the textile carrier (5) is transferred, Transporting the fibrous web (2) through the heating zone (Z2) with the aid of the first metal belt (3) or second metal belt (20) and thermally drying the fibrous web (2) in the heating zone (Z2), wherein the first metal belt (3) or second metal belt (20) leading through the heating zone (Z2) is heated and / or an air flow (L) acting on the fibrous web (2) in the heating zone (Z2) is heated, characterized in that a passage time of the fibrous web (2) through the heating zone (Z2) is in a range from 1.1 s to 11 s.

2. Method according to claim 1, characterized in that the fibrous web (2) is lifted off the metal strip (3) or the textile carrier by a lifting device (19) after the heating zone (Z2).

3. Method according to claim 2, characterized in that a contact time of the fibrous web (2) or the textile carrier (5) with the heated metal belt (3, 20) is in a range of 1.1 s to 11 s.

4. Method according to one of claims 1 to 3, characterized in that a temperature of the metal strip (3, 20) in the heating zone (Z2) is in a range from 35 °C to 200 °C and / or a temperature of the air flow (L) in the heating zone (Z2) is in a range from 40 °C to 650 °C.

5. Method according to one of claims 1 to 4, characterized in that the pressing device (6a, 6b) has an endless pressing belt (7) which is guided over at least two deflection rollers (8a, 8b), and / or has at least one pressing roller (22) and / or a pressing beam, wherein the pressing device (6a, 6b) is pressed against the first metal strip (3).

6. Method according to one of claims 1 to 5, characterized in that a pressure (p) exerted on the fibrous web (2) by the pressing device (6a, 6b) is in a range from 1 MPa to 8 MPa.

7. Method according to one of claims 1 to 6, characterized in that the dry content of the fibrous web (2) before the pressing zone (ZI) is in a range of 20 to 50%.

8. Device (1a..lc) for processing a fibrous web (2), comprising a first endless metal belt (3) which is guided over at least two deflection rollers (4a, 4b) and which is designed to receive the fibrous web (2) or a textile carrier (5) for the fibrous web (2), a pressing zone (ZI) to and through which the first metal belt (3) leads, wherein the pressing zone (ZI) comprises a pressing device (6a, 6b) which is designed for the mechanical drying of the fibrous web (2), a heating zone (Z2), wherein a) the first metal belt (3) leads to and through the heating zone (Z2) or b) the device (1a..lc) comprises a second metal belt (20) which is designed to receive the fibrous web (2) or the textile carrier (5) from the first metal belt (3) and which leads to and through the heating zone (Z2), and wherein the heating zone (Z2) is designed for the thermal drying of the Fibrous web (2) is designed and comprises a heater (12) for heating the first or second metal belt (3, 20) leading through the heating zone (Z2) and / or for heating an air flow (L) acting on the fibrous web (2) in the heating zone (Z2), and a speed control (17) for controlling a belt speed (v) of the first or second metal belt (3, 20) leading through the heating zone (Z2), which is designed to bring about a passage time of the fibrous web (2) through the heating zone (Z2) in a range from 1.1 s to 11 s.

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