EP4097295A1

EP4097295A1 - Device and method for producing a fibrous web

Info

Publication number: EP4097295A1
Application number: EP20820348.9A
Authority: EP
Inventors: Boris JANCIC; Lukas GISSING; Stefano MARENCO; Klaus Gissing
Original assignee: Andritz AG
Current assignee: Andritz AG
Priority date: 2020-01-30
Filing date: 2020-12-01
Publication date: 2022-12-07
Also published as: AT522459B1; BR112022009277A2; MX2022009341A; CN115038835A; US20230030264A1; WO2021151559A1; US12006631B2; AT522459A4; CN115038835B; CA3160108A1

Abstract

The invention relates to a device and a method for producing a fibrous web (9), in the case of which the first fabric (4) and the second fabric (3) partially wrap around the forming roll (2) and a further roll (11). It is characterized in that the fibrous web (9) which is formed is guided on the first fabric (4) between the forming roll (2) and the further roll (11), and the second fabric (3) is guided separately from the first fabric (4) at least in a part region (5). This allows production of a fibrous web with a small energy consumption and low operating costs.

Description

DEVICE AND METHOD FOR MANUFACTURING A FIBER WEB

The invention relates to a method for producing a fibrous web, in particular a tissue web or hygiene paper web, in which a fibrous suspension is introduced via a headbox between a first circumferential covering designed as a felt and a second circumferential covering designed as a forming fabric and centrifugally in the area of a forming roll to form the fibrous web is dewatered, the first covering and the second covering partially wrap around the forming roller, the first covering is guided between the forming roller and the second covering, the first covering and the second covering partially wrap around another roller and the first covering between the further roller and the second covering is performed. The invention also relates to a device for producing a fibrous web as specified in the preamble of claim 7.

In general, to produce a fibrous web, in particular a tissue or hygiene paper web, a fibrous suspension is introduced via a headbox between two fabrics, the two fabrics partially wrapping around a forming roller and the fiber suspension being centrifugally dewatered in the area of the forming roller. The Crescent Former concept is used in particular in the area of tissue production, i.e. the fiber suspension is introduced between a felt and a forming wire, the fiber web being formed by the dewatering of the fiber suspension. By definition, the crescent former concept also means that the felt is arranged between the forming wire and the forming roll. After the formation of the fibrous web, the forming fabric is lifted off the fibrous web, the fibrous web lying on the felt being fed to the further process steps, including further mechanical and / or thermal dewatering and rolling up to form the end product.

In WO 2017/060053 A1, a method for producing a fibrous web is disclosed and characterized in that the fibrous web, together with the forming wire and the felt, passes over a suction roll immediately after the forming roll to be led. Thus, a method for tissue production is provided in which the highest possible quality tissue is produced.

DE 102011 007568 A1 describes a device and method for producing a material web, which is characterized in that a permeable press belt is brought into contact with the fibrous web in a press zone. This increases the flexibility with regard to the production of different types of paper.

The aim of the invention is an optimized production of a fibrous web with low energy consumption, low operating costs and low investment costs while at the same time improving the quality properties of the fibrous web.

This is achieved according to the invention in that the fibrous web formed is guided between the forming roll and the further roll on the first covering, the second covering being guided separately from the first covering at least in a partial area between the forming roll and the further roll. During the centrifugal dewatering of the fibrous web in the area of the forming roll, the fibrous stock from the fibrous suspension is essentially retained on the second clothing, the liquid of the fibrous suspension - usually water or process water - being thrown off through the second clothing. However, this leads to saturation of the second covering with water or to a high water loading of the second circumferential covering. According to the invention, the second circumferential covering is guided separately from the first covering at least in a partial area between the forming roller and the further roller, whereby it is also possible to lift the second circumferential covering from the first circumferential covering already on the forming roller and only on the another roller to place the second circumferential covering again on the circumferential first covering. By lifting the second circumferential covering from the first circumferential covering, the fibrous web formed being guided on the first covering, the possibility opens up of conditioning the second circumferential covering, and in particular of reducing the water load of the separately guided second covering. Lifting the second covering also opens up more effective ways of conditioning the second covering, since there is no risk of a there is a harmful effect on the fibrous web formed on the first covering. An advantageous sequence of conditioning the second circumferential covering comprises the steps: cleaning the second circumferential covering after lifting the second circumferential covering from the first circumferential covering using a high pressure spray pipe, optional reduction of the water load of the separately guided second covering via a suction box, reduction of the Water loading of the separately guided second clothing via a means for the outflow of a fluid as well as an optional further reduction of the water loading of the separately guided second clothing via a suction box. A person skilled in the art will obviously identify compressed air nozzles, slot nozzles, air blades as such means for the outflow of a fluid. With regard to the fluid, air, compressed air, hot air, process air etc. are suitable. The fluid advantageously has a pressure of 0.1-2.0 bar overpressure. The conditioned second circumferential clothing is then placed back onto the first clothing in an area in front of the further roller or directly on the further roller. The fibrous web can then advantageously be dewatered further in the area of the further roller. A diameter of the further roll smaller than the diameter of the forming roll is also conceivable, which results in greater centrifugal dewatering on the further roll compared to the dewatering on the forming roll, or an embodiment of the further roll as a suction roll.

A favorable embodiment of the invention is characterized in that the first covering is guided over the further roller designed as a suction roller. It is particularly advantageous if a vacuum in the range of 2 - 6 m water column is applied via the suction roll. In the production of a fibrous web, in particular a tissue web, the first circumferential covering is expediently designed as a felt and the second circumferential covering as a forming fabric. The fibrous web formed has the tendency to preferentially follow the felt, ie when the forming wire is lifted from the felt, the fibrous web formed will follow the felt, whereby according to the invention the fibrous web formed follows the first covering between the forming roll and the further roll. The execution of the further roller as a suction roller allows increased dewatering of the web formed in the area of the further roller. According to the invention, the drainage of the web formed by the suction roll is improved when the Forming wire is guided separately from the felt at least in a partial area between the forming roll and the suction roll. This applies in particular when the forming fabric is conditioned in the partial area and the water load on the separately guided forming fabric is reduced.

A further advantageous embodiment of the invention is characterized in that working air and / or steam is applied to the forming wire in the area of the suction roll, the suction roll sucking in the working air and / or steam through the forming wire in the direction of the fibrous web. The application of industrious air and / or steam leads to an increase in temperature of the fibrous web to be dewatered, or to an increase in the temperature of the water in the fibrous web or in the coverings. As a result of the temperature increase, the viscosity of the water is reduced. A reduced viscosity is advantageous with regard to the drainability of the fibrous web. It is advisable to use process exhaust air, e.g. exhaust air from the thermal drying device, such as a Yankee Flaube. Preference is given to using industrial air in a temperature range between 120 ° C. and 200 ° C. and with a moisture content between 0.2 kg / kg and 0.7 kg / kg and / or steam in a pressure range of 0.2-2.0 bar overpressure .

An advantageous embodiment of the invention is characterized in that first the second clothing runs off the forming roll and then the first clothing and the fibrous web guided on it run off the forming roll, whereby the second covering is lifted from the fibrous web guided on the first covering. In this way, the second covering is lifted off the first covering as early as possible, further rewetting of the web formed being prevented.

Another advantageous embodiment of the invention is characterized in that water loading of the separately guided second clothing is reduced in the partial area between the forming roll and the further roll. By reducing the water load of the second covering in the partial area and then placing the second covering on the first covering, the web formed being guided between the first covering and the second covering, further dewatering of the fibrous web follows. In the process, water from the fibrous web is absorbed by the second covering. The improved drainage is particularly pronounced when the another roller is designed as a suction roller. A second covering, the water load of which is not reduced in front of the suction roll, conversely leads to the water being sucked from the second covering into the fibrous web formed. According to the invention, the fibrous web is optimally dewatered by the suction roll, since a second covering with reduced water loading leads to significantly lower rewetting, whereby the dewatering of the fibrous web by suction via the suction roll is more effective.

An equally advantageous embodiment of the invention is characterized in that the further roller and a press roller form a pressing area, the first covering between the fibrous web and the further roller being guided through the pressing area and the second covering between the fibrous web and the pressing roller being guided through the pressing area to be led. The formation of a press area promotes dewatering of the fibrous web in the area of the further roller. The press roller is advantageously pressed against the further roller with a line load in the range of 10-40 kN / m.

The invention also relates to a device for producing a fibrous web, in particular a tissue web or hygiene paper web, according to patent claim 7. In this case, a clothing run comprises an endlessly revolving clothing and clothing guiding means, the respective clothing guiding means being at least partially in contact with the respective revolving clothing. Clothing guide means typically include rollers such as idler rollers, regulating rollers, and tension rollers. Coverings are typically endless and therefore form a loop. Accordingly, machine elements can therefore be arranged inside or outside the loop. The outer string guide means of the second string run is arranged outside of the endlessly encircling second skin forming a loop, the second skin partially wrapping around the outer string guide means. Such an arrangement allows an advantageous dewatering of the fibrous web that is formed.

An equally advantageous embodiment of the device is characterized in that the first endlessly revolving clothing is a felt and the second endlessly revolving clothing is a forming wire. Crescent Former are characterized by the formation of the first covering by a felt and the second Covering through a forming fabric. Advantageously, however, an external clothing guide means is assigned to the second clothing run, the external clothing guide means being arranged in the area between the forming roller and the further roller between the first and the second clothing.

Another favorable embodiment of the device is characterized in that the further roller is designed as a suction roller. The fibrous web guided on the first covering can thus advantageously be dewatered, the suction effect from the suction roll acting on the first covering, the fibrous web and further on the second covering. The suction roll has 1, 2 or 3 suction zones.

An equally favorable embodiment of the device is characterized in that a means for applying industrial air and / or steam in the direction of the suction roll is provided in the area of the suction roll, the means for applying industrial air and / or steam being arranged within the second clothing run. In cooperation with the suction effect by the suction roll, there is sucking in of industrial air and / or steam into the second covering, through the fibrous web and the first covering into the suction roll. The application of industrial air and / or steam is advantageous for dewatering by the suction roll, since an increase in temperature is associated with a decrease in the viscosity of water. The means for applying diligent air and / or steam is arranged in the second clothing run, which is advantageous for dewatering, since the wrapping of the suction roll creates a force (pressure effect) on the fibrous web from the tension of the second circumferential clothing and from the application A rise in temperature of the fibrous web follows from industrial air and / or steam, as a result of which the dewatering behavior is improved. A person skilled in the art will obviously consider steam blow boxes, drying hoods for the application of industrious air and / or steam or the like as means for applying industrious air and / or steam.

A particularly advantageous embodiment of the device is characterized in that means for reducing the water load of the second circumferential clothing are provided between the forming roll and the further roll. The fibrous web is in the area between the forming roll and the further roll The first covering is guided and the second covering is guided at least in a partial area separated from the first covering, the second covering being guided over the outer covering guide means of the second covering run and the outer covering guide means being arranged between the first endless covering and the second endless covering. By reducing the water loading of the second circumferential clothing, when the second circumferential clothing is subsequently re-laid on the first circumferential clothing guiding the fibrous web, the web is dewatered. The dewatering of the web is particularly pronounced when the further roll is designed as a suction roll. The means for reducing the water load comprise a means for the outflow of a fluid, the outflow means being arranged outside the second stringing run. Furthermore, a person skilled in the art will obviously identify compressed air nozzles, slot nozzles, air blades as such means for the outflow of a fluid. Air, compressed air, hot air, process air etc. are available as fluids, with water optionally being added to the fluid. The addition of water allows the temperature of the hot air to be reduced. Due to the arrangement of the means for outflow outside of the second clothing run and the outflow of the fluid in the direction of the second clothing, the fluid will in particular not flow in the direction of the fibrous web or the first covering, which means that dewatering of the second circumferential covering has no adverse effect on the fibrous web given is.

In a particularly advantageous embodiment, the means for the outflow of a fluid is arranged in the inlet area between the outer clothing guide means and the second endlessly encircling clothing. In this case, the fluid from the means for the outflow of a fluid is introduced into the gusset, formed by the inlet area between the outer covering guide means and the second endlessly rotating covering, whereby the fluid is additionally pressed through the second covering. Such an effect is also known as the register roller effect. In a further advantageous embodiment, the means for reducing the water load comprise a means for suctioning the second endlessly rotating covering. Such means for suction include suction strips, suction boxes or the like. An equally favorable embodiment is characterized in that a press roller is arranged in the area of the further roller, the press roller being arranged within the second clothing run and a pressing area being able to be formed by the further roller and the press roller. The press roller is advantageously rubberized with a hardness between 30-50 P&J. The invention will now be described by way of example with reference to the drawings.

Fig. 1 shows an apparatus for producing a fibrous web according to the prior art.

Fig. 2 shows a further device for producing a fibrous web according to the prior art. Fig. 3 shows a first device according to the invention for producing a fibrous web.

Fig. 4 shows a second device according to the invention for producing a fibrous web.

5 shows a third device according to the invention for producing a fibrous web.

1 shows a device for producing a fibrous web 9 in accordance with the prior art shown in WO 2017/060053 A1. A fiber suspension is introduced via a headbox 1 between a first circumferential covering 4 designed as a felt and a second circumferential covering 3 designed as a forming wire and dewatered centrifugally in the area of a forming roll 2, the felt and the forming wire partially looping around the forming roll 2 and the felt is guided between the forming roll 2 and the forming wire. The felt and the forming wire are passed over a further roll 11 immediately after the forming roll 2, the further roll 11 being designed as a suction roll and the felt and the forming wire being the further roll 11 partially wrapped around it. The felt is guided between the further roller 11 and the forming wire. To support the dewatering on the further roller 11, a means 12 for the application of industrial air and / or steam can be provided, in which case the further roller 11 is advantageously designed as a suction roller. The fiber band 9 is guided after the further roller on the first covering 4 and further dewatered. Optionally, an impingement dryer 8 can be provided for thermal drying of the fibrous web 9. The fibrous web is transferred from the felt to a Yankee 6 in a press nip, with further mechanical dewatering being able to be achieved in the press nip. The web is further thermally dried on the Yankee 6, with an optional Yankee Flaube 7 allowing improved thermal drying. Yankee Flauben 7 are typically designed as impingement dryers. The fibrous web 9 is typically removed from the Yankee 6 by creping.

Fig. 2 shows a further device for felling a fibrous web 9 according to the prior art. A fiber suspension is introduced via a headbox 1 between a first circumferential covering 4 designed as a felt and a second circumferential covering 3 designed as a forming wire and dewatered centrifugally in the area of a forming roll 2, the felt and the forming wire partially looping around the forming roll 2 and the felt is guided between the forming roll 2 and the forming wire. The forming wire is lifted from the felt on the forming roll 2 or immediately thereafter, the fibrous web 9 being continued on the felt and further dewatered. Optionally, an impingement dryer 8 can be provided for thermal drying of the fibrous web 9. The fibrous web is transferred from the felt to a Yankee 6 in a press nip, with further mechanical dewatering being able to be displayed in the press nip. The web is further thermally dried on the Yankee 6, with an optional Yankee Flaube 7 allowing improved thermal drying. Yankee Flauben 7 are typically designed as impingement dryers. The fibrous web 9 is typically removed from the Yankee 6 by creping.

3 shows a first device according to the invention for felling a fibrous web, wherein the fibrous web 9 is in particular a tissue web or flygia paper web. To form the fibrous web 9 is a Fibrous suspension introduced via a headbox 1 between a first circumferential covering 4 designed as a felt and a second circumferential covering 3 designed as a forming fabric and dewatered centrifugally in the area of a forming roll 2. The first covering 4 and the second covering 3 partially wrap around the forming roller 2, the first covering 4 being guided between the forming roller 2 and the second covering 3. The first covering 4 and the second covering 3 partially wrap around a further roller 11, the first covering 4 being guided between the further roller 11 and the second covering 3. In particular, the fibrous web 9 formed is guided between the forming roll 2 and the further roll 11 on the first covering 4, the second covering 3 being guided separately from the first covering 4 at least in a partial area 5 between the forming roll 2 and the further roll 11. As shown in FIG. 3, the second clothing 3 is still lifted from the first clothing 4 on the forming roller 2 and guided over the external web guide means 13 of the second clothing run, the fibrous web 9 being guided further on the first clothing 4. The second clothing 3 is then placed back onto the first clothing 4 on the further roller 11, the sub-area 5 being defined as the area between the forming roller 2 and the further roller 11 in which the second clothing 3 is guided separately from the first clothing 4. Advantageously, the water loading of the separately guided second covering 3 is reduced in the sub-area 5 via means for reducing the water loading, the means for reducing the water loading comprising means 14 for outflow of a fluid and / or means 15 for sucking up the second endlessly revolving covering 3. The means 14 for the outflow of a fluid is advantageously arranged outside the second clothing run, with air, compressed air, hot air, process air, etc. being available as the fluid and a person skilled in the art obviously using compressed air nozzles, slot nozzles, air blades as such means 14 would consider for the outflow of a fluid. The means 14 for the outflow of a fluid is also advantageously arranged in the inlet area between the outer clothing guide means 13 and the second endlessly circumferential clothing 3. The means 15 for the suction of the second endlessly revolving covering comprise suction strips, suction boxes or the like. The further roller 11 is advantageously designed as a suction roller, with optionally hot air and / or steam being applied to the forming fabric via a means 12 for applying hot air and / or steam, and the suction roll sucks in the hot air and / or steam through the forming fabric in the direction of the fibrous web 9. According to the invention, the fibrous web 9 is guided after the further roller 11 on the first covering 4 and further mechanically and / or thermally dewatered.

Fig. 4 shows a second device according to the invention for producing a fibrous web. Compared to the illustration of the first device according to the invention in FIG. 3, the illustration of the second device according to the invention in FIG. 4 differs in particular in that a press roller is arranged in the area of the further roller 11 within the second clothing run, with a pressing area being provided by the further roller 11 and the press roller 10 can be formed and the first circumferential covering 4, the fibrous web 9 and the second circumferential covering 3 are guided through the pressing area. The other explanations relating to the first device according to the invention in FIG. 3 apply accordingly to the second device according to the invention in FIG. 4.

Fig. 5 shows a third device according to the invention for producing a fibrous web. Compared to the representation of the first device according to the invention in FIG. 3, the representation of the third device according to the invention in FIG second clothing run is performed, wherein the fibrous web 9 is guided on the first clothing 4. The second clothing 3 is then placed back onto the first clothing 4 in front of the further roller 11, the sub-area 5 being defined as the area between the forming roller 2 and the further roller 11 in which the second clothing 3 is guided separately from the first clothing 4. The other explanations relating to the first device according to the invention in FIG. 3 are correspondingly valid for the third device according to the invention in FIG. 5.

The present invention thus offers numerous advantages. An optimized production of a fibrous web is given, with a significantly improved dewatering of the fibrous web in the area between the forming roll and another roller. In particular, this significant improvement in the dewatering of the fibrous web can be achieved with simple means, such as means for the outflow of a fluid, the fluid allowing a reduction in the water load of the second circumferential clothing and consequently a significantly improved dewatering of the fibrous web on the further roller. In this way, the total energy consumption can be reduced compared to prior art solutions. Furthermore, the solution according to the invention allows these advantages to be realized with low investment costs, two - ie a first and a second - circumferential covering being sufficient for the realization. The invention also allows an improvement in the quality properties of the fibrous web, such as the fibrous web volume ("bulk") or the fibrous web thickness ("caliper"), since the improved dewatering of the fibrous web improves the maintenance of these quality properties in the subsequent drying of the fibrous web, in particular during subsequent mechanical pressing, allowed.

Reference number

(1) headbox

(2) Forming roll

(3) Second circumferential covering, forming fabric

(4) first circumferential covering, felt

(5) Sub-area

(6) Yankee

(7) Yankee Flaube

(8) Impingement dryer

(9) fibrous web

(10) press roll

(11) another roller

(12) Means for applying industrious air and / or steam

(13) external stringing guide means

(14) Means for the outflow of a fluid

(15) Means of suction

Claims

1. A method for producing a fibrous web (9), in particular a tissue web or hygiene paper web, in which, to form the fibrous web (9), a fibrous suspension via a headbox (1) between a first circumferential covering (4) designed as a felt and one designed as a forming fabric Second circumferential covering (3) is introduced and dewatered centrifugally in the area of a forming roll (2), the first covering (4) and the second covering (3) partially wrapping around the forming roll (2), the first covering (4) between the forming roll (2) and the second covering

(3), the first covering (4) and the second covering (3) partially wrap around a further roller (11) and the first covering (4) is guided between the further roller (11) and the second covering (3) , characterized in that the fibrous web (9) formed is guided between the forming roll (2) and the further roll (11) on the first covering (4), the second covering (3) at least in a partial area (5) between the Forming roller (2) and the further roller (11) is guided separately from the first covering (4).

2. The method according to claim 1, characterized in that the first covering

(4) is guided over the further roller (11) designed as a suction roller.

3. The method according to claim 2, characterized in that hot air and / or steam is applied to the forming wire in the area of the suction roll, the suction roll drawing in the hot air and / or steam through the forming wire in the direction of the fibrous web (9).

4. The method according to claim 1, characterized in that first the second covering (3) runs off the forming roll (2) and then the first covering (4) and the fibrous web (9) guided thereon runs off the forming roll (2), whereby the second covering (3) is lifted off the fibrous web (9) guided on the first covering (4).

5. The method according to claim 1, characterized in that a water load of the separately guided second clothing (3) in the sub-area (5) between the forming roller (2) and the further roller (11) is reduced.

6. The method according to claim 1, characterized in that the further roller (11) and a press roller (10) form a press area, wherein the first Covering (4) is guided between the fibrous web (9) and the further roller (11) through the press area and the second covering (3) is guided between the fibrous web (9) and the press roll (10) through the pressing area.

7. Device for the production of a fibrous web (9), in particular a tissue web or flygia paper web, with a headbox (1), a first clothing run, a second clothing run, a forming roll (2) and at least one further roll (11), the first covering run comprises a first endlessly revolving clothing (4) and first clothing guide means, the second clothing run comprises a second endlessly revolving clothing (3) and second clothing guide means, the forming roller (2) and the further roller (11) within the first endlessly revolving clothing (4) are arranged, the forming roller (2) and the further roller (11) being partially looped by the first endlessly rotating clothing (4), the forming roller (2) and the further roller (11), however, outside the second endlessly rotating clothing (3) are arranged and a partial looping of the forming roll (2) and the further roll (11) by the second end loose circumferential covering (3), the first circumferential covering (4) being arranged between the second circumferential covering (3) and the forming roller (2) and furthermore the first circumferential covering (4) between the second circumferential covering (3) and the further roller (11) is arranged and the headbox (1) is designed for introducing a fiber suspension between the first endlessly rotating clothing (4) and the second endlessly rotating clothing (3), characterized in that between the forming roller (2) and the further roller (11), the second clothing run comprises an external clothing guide means (13) and the external clothing guide means (13) is arranged outside the endlessly circulating second clothing (3), the external clothing guide means (13) between the first endlessly circulating clothing ( 4) and the second endlessly revolving covering (3) is arranged.

8. The device according to claim 7, characterized in that the first endlessly revolving covering (4) is a felt and the second endlessly revolving covering (3) is a forming wire.

9. Apparatus according to claim 7, characterized in that the further roller (11) is designed as a suction roller.

10. The device according to claim 9, characterized in that a steam box or a drying hood for the discharge of hot air and / or steam in the direction of the suction roll is provided in the area of the suction roll, the steam box or the drying hood for discharging hot air and / or steam is arranged within the second stringing run.

11. The device according to claim 7, characterized in that means for reducing the water load of the second circumferential covering (3) are provided between the forming roll (2) and the further roll (11).

12. The device according to claim 11, characterized in that the means for reducing the water load comprise an outflow means (14), the outflow means (14) being arranged for outflow outside the second stringing run and the outflow means (14) comprising compressed air nozzles, slot nozzles or air blades .

13. The device according to claim 12, characterized in that the outflow means (14) is arranged in the inlet area between the outer clothing guide means (13) and the second endlessly circumferential clothing (3).

14. The device according to claim 11, characterized in that the means for reducing the water load comprise suction strips or suction boxes for suctioning the second endlessly rotating covering (3).

15. The device according to claim 7, characterized in that a press roller (10) is arranged in the area of the further roller (11), the press roller (10) being arranged within the second clothing run and a pressing area through the further roller (11) and the press roll (10) can be designed.