Patent Application
20240254692
The invention relates to a device for reducing a moisture content of a moist, fiber-containing material.
The invention further relates to an endless belt for a device of the abovementioned kind.
During the manufacture of different products from fiber-containing materials, such as different kinds of paper, for example, or other products, it is very often required to dry a moist, fiber-containing material, for example in the form of a fiber web.
A device of the kind mentioned in the beginning has become known from U.S. Pat. No. 8,486,229B2. In the known device, the material to be dried, which has the form of a fiber web in that case, is guided through a heated drying zone on an endless belt of metal. A disadvantage of the known device is in particular that a high energy use is required for the heating.
It is therefore an object of the present invention to overcome the disadvantages of the prior art and realize an efficient reduction of a moisture content of fiber-containing material.
In accordance with the invention, this object is achieved with a device of the kind mentioned in the beginning in that the device has a double-belt press with a first endless belt 1 and a second endless belt, wherein a pressing zone for pressing liquid out of the fiber-containing material is configured between the first endless belt and the second endless belt, wherein, further, a belt of a liquid-absorbing material that is guided between the two endless belts and through the pressing zone is arranged, wherein a surface of the belt of liquid-absorbing material that faces the first endless belt forms a contact surface for the fiber-containing material.
The solution in accordance with the invention enables liquid to be pressed out of the material to be dried, and therefore the degree of moisture of the material to be reduced, in a purely me-chanical manner and therefore a highly energy-efficient reduction of the moisture content to be realized.
In accordance with a preferred variant of the invention, it can be provided that the first and the second endless belt are made from metal. Even though the endless belts are preferably formed from metal, also plastics, composites (fiber-reinforced plastic) or suchlike can, alternatively or additionally, be used as materials for the endless belts.
In accordance with a preferred variant of the invention, it can be provided that the belt of liq-uid-absorbing material is configured as an endless belt. This variant of the invention enables a highly efficient and uninterrupted operation of the device. For example, after a moisture tran-sition from the material to be desiccated to the belt of liquid-absorbing material, a partial region of this belt can be desiccated, at least in part, and guided back into the device and made available to the process again.
In accordance with a preferred variant of the invention, it is provided that the top endless belt and the bottom endless belt, as well as the belt of liquid-absorbing material, are driven and are each arranged circumferentially between at least two rollers. This variant of the invention al-lows, for example, a simple change of the revolving speeds of the individual belts and therefore a change of the velocity with which the material to be dried is transported through the device. Here, at least one of the rollers can be heated.
In accordance with one advantageous advancement of the invention, the top endless belt can have a circumferential length selected from the range from 3 m to 200 m, the bottom endless belt a circumferential length selected from the range from 3 m to 200 m and the belt of liquid-absorbing material a circumferential length selected from the range from 5 m to 250 m.
Further, the top endless belt and the bottom endless belt can each have a thickness selected from the range from 0.1 mm to 3.5 mm, in particular from 0.2 mm to 1.5 mm, wherein the belt of liquid-absorbing material preferably has a thickness selected from the range from 1 mm to 10 mm, in particular from 2 mm to 4 mm.
Furthermore, it has proven particularly advantageous that a width of the first endless belt and a width of the second endless belt and a width of the belt of liquid-absorbing material, in each case, is greater than 0.5 m, preferably greater than 1.5 m, particularly preferably greater than 4 m.
A discharging of liquid already in the device and from the pressing zone is facilitated in that an outer side of the second endless belt that faces the belt of liquid-absorbing material has channels for discharging the liquid that run in a circumferential direction of the second end-less belt, or diagonally to the circumferential direction of the second endless belt, preferably circumferential channels that run in a closed loop in a circumferential direction of the second endless belt, wherein the channels preferably have a depth between 50 μm and 1000 μm, in particular between 70 μm and 300 μm.
A draining of liquid is also facilitated by the bottom endless belt having cups, in particular blind holes, for receiving the liquid on the outer side of the belt.
The cups can be arranged next to and/or between the channels and end in the channels and/or be connected with the channels via conduits.
One variant of the invention has proven particularly favorable for discharging liquid from the fiber-containing material, in which variant of the invention the belt of liquid-absorbing material is configured as a belt of a textile fabric, in particular of a non-woven textile fabric, in particular felt or fiber web.
In accordance with a preferred advancement of the invention, the belt of liquid-absorbing material can have a weight per unit area selected from the range from 500 g/m2 to 2500 g/m2 and/or a tensile strength selected from the range from 30 N/mm to 90 N/mm.
In accordance with a preferred variant of the invention, the belt of liquid-absorbing material is also configured as permeable to liquid.
In another variant of the invention, which enables an excellent discharging of the liquid, it can be provided that the second endless belt is guided away from the transport belt by means of at least one deflection device, in particular by means of at least one deflection roller, in a liquid suction zone arranged upstream and/or downstream of the pressing zone in a transport direction of the fiber-containing material, which liquid suction zone serves to suck off the liquid pressed out of the fiber-containing material in the pressing zone, so that the belt of liquid-absorbing material does not rest against the second endless belt in the liquid suction zone and a free space between the belt of liquid-absorbing material and the second endless belt is formed in the liquid suction zone, wherein the device has a device for sucking the liquid in the region of the free space off the second endless belt, in particular a suction device, for example in the form of a suction pump and/or vacuum chamber with at least one inflow for the liquid, wherein the belt of liquid-absorbing material rests against the second endless belt in the pressing zone.
To separate the fiber-containing material from the belt of liquid-absorbing material, it can be provided that a separation zone is arranged downstream of the pressing zone in a transport direction of the fiber-containing material, wherein the second endless belt is guided downwards, away from the first endless belt, together with the belt of liquid-absorbing material by means of at least one deflection device, in particular by means of at least one deflection roller, in the separation zone, wherein a gap is formed between the belt of liquid-absorbing material and the first endless belt in the separation zone.
The fiber-containing material can be detached from the belt of liquid-absorbing material particularly easily in that at least one nozzle for generating a gas flow, in particular an air knife, is arranged in the gap in the separation zone and is directed opposite the transport direction of the material and between the belt of liquid-absorbing material and the first endless belt.
A further drying of the fiber-containing material can be achieved in that an impingement drying device with at least one air outlet directed against a side of the fiber-containing material that faces the belt of liquid-absorbing material is arranged in the gap in the separation zone.
Further, it can be provided that, to extend the process line, the fiber-containing material is guided further, from a side of the first endless belt that faces the second endless belt to a side of the first endless belt that faces away from the second endless belt.
In accordance with the invention, the abovementioned object can also be achieved with an endless belt of the kind mentioned in the beginning in that an outer side of the belt of the end-less belt has cups, in particular blind holes, for receiving the liquid and/or has channels for discharging the liquid that run in a circumferential direction of the endless belt, or diagonally to the circumferential direction of the endless belt, preferably channels that run in a closed loop in a circumferential direction of the second endless belt, wherein the channels preferably have a depth between 50 μm and 1000 μm, in particular between 70 μm and 300 μm.
The cups can be arranged next to and/or between the channels and end in the channels and/or be connected with the channels via conduits.
As mentioned further above, the endless belt is preferably manufactured of metal, although it can also be produced of other materials, such as plastic, composites, such as fiber-reinforced plastics, etc.
For the purpose of better understanding of the invention, it will be elucidated in more detail by means of the figures below.
These show in a respectively very simplified schematic representation:
First of all, it is to be noted that, in the different embodiments described, equal parts are provided with equal reference numbers and/or equal component designations, where the disclo-sures contained in the entire description may be analogously transferred to equal parts with equal reference numbers and/or equal component designations. Moreover, the specifications of location, such as at the top, at the bottom, at the side, chosen in the description refer to the directly described and depicted figure, and in case of a change of position, these specifications of location are to be analogously transferred to the new position.
Any and all specifications of value ranges in the description at issue are to be understood to comprise any and all sub-ranges of same, for example the specification between 1 and 10 is to be understood to mean that any and all sub-ranges starting from the second limit 1 and from the first limit 10 are comprised therein, i.e. any and all sub-ranges start at a second limit of 1 or larger and end at a first limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.
In accordance with
In the region designated with I, there is an inlet for the material 2 into the double-belt press, whereas the region designated with II represents an outlet for the material 2. Here, the material 2 is transported through the double-belt press in the direction represented with an arrow, from left to right in the drawing. The material 2 can be applied to the top endless belt 3 with a pouring device 2a, for example, such as this is represented in
A region between a side 3a of the first endless belt 3 and a side 4a of the second endless belt 4 is configured as a pressing zone 5 for pressing liquid out of the fiber-containing material 2. The fiber-containing material 2 can be a fiber web, for example. Preferably, the fibers are cel-lulose fibers from renewable resources. The liquid can be water, for example. In this case, the device 1 serves to reduce the water content in the fiber-containing material 2.
In the pressing zone 5, the two endless belts 3, 4 can be pressed against each other with, preferably pressure-loaded, rollers, roller carpets, sliding plates and/or hydraulic and/or hydro-static pressure means, for example, which are not represented here, in order to exert a pressing force on the fiber-containing material 2. Yet, it is also possible to set the size of a pressing gap in the pressing zone 5 bounded by the two endless belts 3, 4 to a fixed value, wherein, when running through the pressing gap, the fiber-containing material 2 is compressed and liquid is pressed out of the material 2 in accordance with the distance between the side 3a of the first endless belt 3 from the side 4a of the second endless belt 4.
Preferably, a pressure between 0.1 to 20 MPa (1 to 200 bar) is exerted on the fiber-containing material 2 in the pressing zone 5. A pressure between 0.1 to 20 MPa is therefore ensured between the first endless belt 3 and the second endless belt 4 in the pressing zone 5.
Further, a belt 6 of a liquid-absorbing material is guided between the two endless belts 3, 4 and through the pressing zone 5. Particularly preferably, the material of the belt 6 is configured as not only liquid-absorbing but also permeable to liquid. A surface of the belt 6 of liq-uid-absorbing material that faces the first endless belt 3 forms a contact surface and/or a sup-porting surface for the fiber-containing material 2. The belt 6 serves to receive liquid from the material 2 and rests against the side 4a of the second endless belt 4 in the pressing zone 5.
The belt 6 can also be configured as an endless belt. Preferably, the belt 6 is configured as a belt of a textile fabric, in particular of a non-woven textile fabric, in particular felt or fiber web. A weight per unit area of the material from which the belt 6 is made can advantageously be between 500 g/m2 and 2500 g/m2. Further, the belt 6 can have a tensile strength between 30 N/mm to 90 N/mm.
As can further be gleaned from
Lengths and widths of the belts can vary. For example, the top endless belt 3 and the bottom endless belt 4 can each have a circumferential length between 3 m to 200 m and the belt 6 of liquid-absorbing material can have a circumferential length between 5 m to 250 m. Here, the belt 6 is larger in its circumferential length than the bottom endless belt 4. Also, the first end-less belt 3 can have a smaller circumferential length than the bottom endless belt 4, for example. However, this is not imperatively so: the endless belts 3 and 4 can also have the same circumferential length. Yet, it is also possible that the bottom endless belt 4 has a smaller circumferential length than the top endless belt 3.
Further, the top endless belt 3 and the bottom endless belt 4 can each have a thickness between 0.1 mm and 3.5 mm, in particular between 0.2 mm and 1.5 mm. In a dry state, the belt 6 of liquid-absorbing material preferably has a thickness between 1 mm and 10 mm, in particular between 2 mm to 4 mm.
A width of the first endless belt 3 and of the second endless belt 4, as well as of the belt 6, can be greater than 0.5 m, preferably greater than 1.5 m, particularly preferably greater than 4 m.
As can be seen from
To further improve the discharge of liquid, it can be provided that the bottom endless belt 4 has cups 15, in particular blind holes, for receiving the liquid on the outer side of the belt. The cups 15 can be arranged next to and/or between the channels 14 and be connected with the channels 14. For example, the cups 15 can end in the channels or be connected with the channels 14 via conduits. A diameter of the cups 15 can be greater than a width of the channels 14, for example. Yet, it is also possible to provide only the cups 15 or only the channels 14 in the endless belt 4.
As can further be seen from
In the free space 18 created in the liquid suction zone 16 between the belt 6 and the side 4a of the second endless belt 4, the liquid can be sucked off the outer side of the belt 13 (
A separation zone 20 can be arranged downstream of the pressing zone 5 in a transport direction of the material 2. In the separation zone 20, the side 4a of the second endless belt 4 is guided downwards, away from the first endless belt 3, together with the belt 6 by means of at least one deflection device 21, in particular by means of at least one deflection roller. Between the belt 6 and the side 3a of the first endless belt 3, a gap 22 is formed in the separation zone 19.
In the gap 22, an air knife 23 directed opposite the transport direction of the material 2 and between the belt 6 and the side 3a of the first endless belt 3 can be arranged. In this manner, the material 2, which adheres in part to an outer side of the side 3a can be separated from the belt 6, so that it then only adheres to the side 3a and is transported by same to the outlet II, where it can be detached from the first endless belt 3, for example by means of a scraper or of a stripping roller, not represented here in more detail. After being detached from the first end-less belt 3, the material 2 can be subjected to further processing steps.
Further, an impingement drying device 24 with at least one air outlet directed opposite a side of the side 3a of the first endless belt 3 that faces a web of fiber-containing material 2 can be arranged in the gap 22 in order to further increase the degree of dryness of the material 2 before it is detached from the first endless belt.
Further, it can be provided that, to extend the process line, the fiber-containing material 2 is guided further, from the side 3a of the first endless belt 3 that faces the second endless belt 4 to a side of the first endless belt 3 that faces away from the second endless belt 4. In the representation of
Finally, as a matter of form, it should be noted that for ease of understanding of the structure, elements are partially not depicted to scale and/or are enlarged and/or are reduced in size.
| Number | Date | Country | Kind |
|---|---|---|---|
| A 50396/2021 | May 2021 | AT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/AT2022/060174 | 5/19/2022 | WO |
