FI75381B - PROFESSIONAL REFERENCE AVAILABILITY. - Google Patents

Description

75381 ^ Method for removing water from a web Förfarande vid awattning av en bana 5

The invention relates to a method for removing water from a paper or board web by mechanical pressing, which method uses a wide pressing zone formed between the press roll and an opposing spraying shoe compared to the area of the roll pair nip. a comb arrangement bounded on the one hand by the spray shoe and said impermeable strip on the side of the web to be pressed and through which the web to be pressed is passed in connection with the press fabric 15, preferably between two press fabrics acting as a web in the direction of travel of the web divided into at least three pressure chamber units insulated from each other and from the outside air by sealing means, extending across the web 20 direction over its entire width.

The most common way previously known to remove water from culture webs, especially paper and board webs, is to pass the web through a spray nipple formed by two opposing rolls. It is known that dewatering nipples 25 use one or two compression fabrics which convey the water discharged from the web and act as a web-conveying fabric.

As the production speeds of paper machines increase, dewatering by nip pressing has become a bottleneck limiting the increase in speed. This is due to the fact that the press-tins nip formed by the pair of rollers are short in their blasting range, so at high speeds the residence time of the web in these press tins remains short. However, especially due to the flow resistance of the fibrous structure of the web, water needs a certain amount of time to leave the web for the roll hollow or press fabric. It is known that several successive press nips have been used, either the so-called compact press section, exemplified by the applicant's 2 75381 1 "Sym-Press" trademark) purlstlnosa or several separate successive presses. However, nip presses take up a relatively large amount of space, especially if separate successive purlstlnnlpps are used. The compact design of the pulp mill, on the other hand, causes difficulties in the optimal placement of the various parts 5 as well as in the use of e.g. Suction rollers commonly use suction rollers, which are relatively expensive components and consume suction energy. The suction roll must use a reloaded jacket, which causes problems with the mechanical strength of the suction rollers.

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If an attempt is made to increase the dewatering efficiency in nlppl presses by increasing the nip pressure, a certain intermediate will be reached where the increase in nlppl pressure no longer helps, as the structure of the ralna and the press fabrics can no longer withstand the spray pressure.

15

Efforts can be made to extend the area of the roll by using larger diameter rolls and soft blown fabrics, but even in these means the limit of economic implementation is quickly met.

20 Due to the problems presented above and for other reasons, a so-called pitkänlpplpuristimla. Reference is made by way of example to U.S. Patents 3,808,092, 3,808,096, 3,840,429, 3,970,515, 4,201,624 and 4,229,253 and GB Patent Application 20,572,027.

In addition, with regard to the prior art, reference is made to FI patent application 3554/72 (Beloit Corporation, USA) and U.S. Patent 3,783,097 (Beloit Corporation, USA). From the former publication, a paper machine sprayer structure for compressing water from a paper web is previously known, which structure is based on the use of flexible belts, the tightening of which belts provides a long pressing belt. However, a disadvantage of this known pltkänipplpurlstlmesea is that the mechanical strength of the press belts and their guide rollers places a limitation on achieving a sufficiently high pressure for efficient dewatering. 1

Em. U.S. Pat. No. 4,847,607 discloses a long end press using a plurality of successive pressure shoes which are pressed toward the opposite belt and press roll. The disadvantage of this solution is that the friction between the pressure shoes and the opposite belt causes considerable energy consumption. In addition, said belt and the heel shoes are subject to severe wear due to abrasion.

3 75381 5 The present invention is incidental to the aforementioned publications U.S. Patent 3,840,429. This reference discloses a long nip press in which a pressable web passes linearly between two felts through a pressurized zone formed by two opposing press shoes. Inside the loops of said felts 10 there are further special strips which delimit the compression zones and transmit the pressure of the medium to the web. Here, the long-press press is present with the compaction light of the spray zone, for which the above-mentioned U.S. patent does not provide any solution. Another disadvantage is that the ralna is immediately subjected to full and necessarily relatively high purging pressure. However, with a low dry matter content, Ralna el can withstand without breaking a larger than a certain limit. Thus, the compression fitting has to be kept relatively low. In any case, from the point of view of the fibrous structure of the web, it is not advantageous to use large sprays which suddenly rise in the initial pile of the press.

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It is an object of the present invention to provide a method which largely avoids the above drawbacks and provides a new and in many respects more useful culture web pressing method.

25

In order to achieve the above and later objects, the method of the invention is mainly characterized in that a full or almost full compression zone treatment bellows is fed from said bellows chamber to the middle or middle ones, while a substantially lower pressure gap is applied to the outermost pressure chambers.

In the spraying process according to the invention, the advantages which are characteristic of long nip presses in general, i.e. a sufficiently long spraying distance and a spraying start, are realized.

4 75381 1 According to the invention, leaks in the bellows can be minimized by reducing the load on the edge seals of the pressure chambers. Thus, well-sealing filler structures known per se can be used as edge fillers.

5

The invention makes it possible to adjust the palm profile both in the direction of travel and in the transverse direction. As the blowing felts develop, it is likely to become possible to perform the compression of the paper or board in only one of the long blasting systems according to the invention, whereby the adjustability of the pressure profile is quite essential.

The following invention will be described in detail with reference to some embodiments of the invention shown in the figures of the accompanying drawing, to the details of which the invention is in no way narrowly limited.

Figure 1 shows a schematic side view of a fibrous web press applying the method of the invention.

Figure 2 shows, as a vertical displacement, the discharge zone of a press applying the method of the invention with sealing means. Figure 2 is at the same time section II-II in Figure 4.

Figure 3 shows graphically the pressure distribution in the spray zone of a press applying the method 25 of the invention.

Figure 4 shows the seals of the extrusion zone and the pressure combs delimited by them, seen from the radial direction of the press roll.

Fig. 5 shows, in a manner similar to Fig. 2, another spraying zone implementing the method of the invention. Figure 5 is at the same time a section V-V in Figure 7.

Figure 6 shows graphically the pressure distribution in the spray zone 35 of Figure 5.

Fig. 7 shows, in a manner similar to Fig. A, the sealing elements of the compression zone and the bellows chambers delimited by them.

5 75381

The paper web is introduced into the press shown in Fig. 1 by a press felt 10. The press shoe 20 and the opposite roll 16 form a zone <* in the press roll 16 for the water from which the water is removed from the web W by pressing. The web WQut follows the felt 10, for example, due to its surface properties. As is known per se, the compressed web WQU® is fed to a sowing section (not shown) of a paper machine for milling-10 drying.

The guide rollers 11 control the flow of the loop of the upper felt 10 and the guide rollers 13 control the loop of the lower felt 12, respectively. In connection with the loops of the felts 11 and 12, the felt restoring devices 19 known per se are shown only schematically. The function of the felts 10 and 12, as in the case of a roller pair press, is to convey the water leaving the ralna W to them in the compression zone and to act as a means for conveying the ralna W forward.

The spray roll 16 is a roll provided with a hollow surface 17, e.g. a grooved or blind drilled surface, preferably a deflection compensated roll. A part of the water leaving the ralna W in the compression zone oi passes through the felt 10 to the hollow 16 of the roll 16, from where it is released by centrifugal forces and ejected into the water collecting trough 18, from which the water is further conveyed as is known.

Inside the lower guide loop 12 there is a strip loop IA guided by the guide rollers 15. The strip IA is a smooth and impermeable structure, e.g. an acid-resistant steel strip, a fabric-reinforced plastic or rubber strip 30 or other similar impermeable strip having sufficient strength. The purge support pressure acts from the bellows gap IA of the shoe chamber of the shoe 20 against the strip IA, which transmits the compression bellows through the lower felt 12 to the paper web W as the roll 16 acts as a counterpart to the compression provided by the shoe 20. The support beam 21 of the pressing shoe 20 is preferably arranged as a deflection compression brush. In connection with the support beam 21, actuators (e1 shown) can advantageously be provided, by means of which the support beam 21 and the pressing shoe 20 can be moved away from their location for opening the compression zone.

6 75381

According to Fig. 2, the pressing shoe 20 has a plurality of grooves 31, 32, 33, 34, 35, 36 and 37 in the direction of travel 5 of the web V, which abut the grooves made in the spray shoe 20. The end flanges 41 and 48 of the shoe 20 and the spaced ends 42, 43, 44, 45, 46 and 47 delimit the sheave 31-37. , 55,56, 10 57 and 58. For example, flexible lip seals are used as edge seals 51 and 58 to obtain a good seal. Intermediate seals 52-57 are hard wear-resistant sealing strips, the proper design of which provides for their self-rolling in the bellows of the chambers 31-37. The seals 51-58 are pressed against the inner surface of the fabric loop 17 by means of pressure means passed both through the springs 60 and from the chambers 31-37 through the channels 61 15 and thus have a sufficient seal.

Figure 4 shows in its entirety the arrangement of the flanges 31-37 delimited by the seals 51-58. As shown in Fig. 4, the edge seals 51 and 58 connect the end seals 51 'as shown in Fig. 4 so as to form a unitary rectangular closed guide ring. Respectively, the inner seals 52 and 57, 53 and 56 and 54 and 55 form rectangular feed rings closed in pairs with the end portions 52 ', 53' and 54 '. The centers of the end seals 51'-54 'are connected by a central 25 seal 59 in the region of both ends of the roll 16. The boiler 59 isolates the end regions 31'-37 'of the pressure zones 31-37. The central clamp 59 is at the center of the central pressure chamber 34 as the axial wave direction of the roll 16.

The sealing ring formed by the seals 54 and 55 and the end seal 54 'is divided, according to the lower part of Fig. 4, by intermediate seals 60 into sub-rings which delimit the central chamber 34 into several successive sub-chambers 34'. 1

According to Figures 2 and 4, the pressing shoe 20 is divided by partitions 42-47 and seals 52-57 and ends in seven flanged chambers which are paired with each other by the ends of the roll 16, separated by a pair of central seals 59. Said chambers 31-37 are supplied with a flue medium by means of a hydraulic pump or a compressed air compressor. The pressures p ^ p ^ iP ^ tP ^ tP ^ fPg and Py of the different chambers are adjusted so that the outermost chambers 31,37 maintain a considerably lower pressure in terms of the duration and leaks of the seals than the invented chambers 32-36.

The stepped bellows shown in Figures 5 and 7 differs from that shown in Figures 2 and 4 in that the extent and distribution of the pressure chambers 31-37 differs from the uniform distribution shown in Figure 10. Figure 5 in accordance with painevyö- zone c> for the first four chambers 4 on the input side of 31,32,33 and 34 are of equal width and equal pitch, followed by a wider kesklkammio 35, and then two narrow trailing chambers 36 and 37. Figure 7 can pressure of the shoe of Figure 5 painekammloiden an arrangement of end chambers 15 31 ^ 32 ^ 33 ^ 361 and 37 'which differs slightly from that shown in Figure 4. Fig. 7 is so illustrative in this respect that it is not necessary to repeat the el described in connection with Fig. 4. The center point 59 is at the widest center chamber 35. As shown at the bottom of Fig. 7, the central chamber 35 can be divided by an intermediate seal 60 into a plurality of successive sub-chambers 35 ', to each of which an adjustable pressure ρ, - ^, ρ,. ^, P ^ c »p ^ ^, etc. can be applied.

Figures 3 and 6 show the distribution of the pressures Pj-Py in the different chambers 31-37 and in the associated end chambers 31'-37 '. According to Fig. 3, the pressure p1 of the first chamber 31 is relatively low, e.g. only about 5 bar. Thereafter, the pressures p £, p ^ and p ^ in the following chambers rise in steps ΔΡ2> ΔΡ3 JaAp ^. In the following chambers 35, 36 and 37, the pressure decreases stepwise with Ap ^ tdpg and Apy. The pressure Py in the last chamber is substantially equal to the pressure p1 in the first chamber 31. The pressure Py is preferably substantially lower than the preceding stages Λρ ^ and Apy

As shown in Fig. 3, the edge separators 51 and 58 and the end seals 51 'connecting them are subjected to a pressure differential pressure of approximately 35, which is substantially equal to Apg. Thus, the flexible lip seals 51,58 and 15 'are also durable as edge seals 51,58 and 15'. The intermediate seals 52-57 can withstand the eropals Δρ2 ~ Ap ^ of the bellows combs 31-37.

In Fig. 3, the areas of the pressure zones are marked on the horizontal axis S with the references of α, 5, α3, α, α, α, α, α, and α2. The areas a ^ -a ^ are flat. The pressure p 1 in the central chamber 34 is the maximum pressure and the pressure p 1 in the next chamber 35. is only a small step Δρ ,. lower the maximum pressure p ^.

Thus, in a way, two regions a ^ and a, are obtained. width of the maximum pressure zone, after which the pressure decreases from the pressure p ^ relative to the largest 10 steps Apg and ΔPy »the last step Apg is quite small due to the loadability of the edge seals 51 'and 58.

According to Fig. 3, a favorable pressure distribution for dewatering and ralna formation as well as compaction of the bellows chambers is obtained, in which the pressure initially rises in relatively small steps, after which there is a central region α 2, α 2 with high pressure and high water extraction capacity. After this, the pressure drops relatively sharply again.

According to Fig. 6, the above effect is further enhanced by the fact that the pressure initially rises, for example, by about 10 bar in two relatively small stages Δρ ^ and Δρ2 *. Thereafter the pressure rise is substantially steeper in the stages Apg, Δρ ^ and Δρ ^. The regions aj-a ^ of the horn chambers 31-34 are flat, followed by a maximum pressure chamber 35 (pressure p ^), the region a ^ of ^ of which is about twice as wide as the regions a ^ -a ^ of the preceding 25. The chamber 35 and the region α1 are followed by two narrower pressure chambers 36 and 37, the regions α1 and α1 being only about half the width of the regions 8j-α1 and in the region of which the pressure initially decreases relative to the largest steps Apg and Δp? the last stage Apg, which is received by the pressure edge 58. According to Figure 6, a steadily rising and relatively slightly rising and relatively sharply decreasing pressure profile is obtained.

The maximum treatment pressure p1, p ^ (full pressure) of the middle chamber 35 or chambers largely determines the dry matter content 35 produced by the press on the web. The bellows profiles shown in Figures 3 and 6 above are only one example of the bellows profiles provided by the long nip press according to the invention. It is to be understood that by appropriate adjustment of the pressures »75381 1 Pj-p ^ any bead profile permitted by the seal structures can be realized. Thus, palneprof1111, of course within the limits allowed by the seal structures, can be chosen to be the most advantageous in terms of water incineration capacity and formation as well as the quality of the product.

According to the lower parts of Figures 4 and 7, the middle maximum pressure chamber 34 is divided longitudinally by seals 62 into a plurality of sub-chambers 34 '. By applying different pressures 10 to these sub-combs 34 ', the transverse moisture profile of the web can be adjusted. The principle of this adjustment is that if there is a higher moisture content at a certain point in the web W, the pressure of the sub-chamber 34 'at this point is adjusted higher, whereby the dewatering is intensified locally and the moisture profile is thus equalized.

15

As the pressure medium to be fed to the chambers 31-37, for example, water, an aqueous oil melt with an oil of e.g. about 3 Z, hydraulic oil, semi-liquid fat, air or air to which a folding alloy has been added can be used.

20

As stated, the appropriate design of the intermediate seal 52-57 results in a controlled leakage between the seals and the strip 14 due to the effect of the pallet port Δρ, which provides a folding film which reduces the wear of the intermediate seal 52-57. In any case, due to the pressure grading, a good seal is obtained, but the seal loads, their heating and the wear of the seals remain small. Said leakage naturally causes a constant need for hydraulic power, but this power is relatively small.

According to Figures 2 and 5, troughs 22 are provided on both the inlet side and the outlet side of the spray shoe 20, in which any bellows gap leaking through the seals is collected and this pressure gap is led to removal or re-use. Corresponding troughs 22 can also be provided at both ends of the shoe 20.

Figures 4 and 7 denote the edges of the web by reference V and the ends of the roll 16 by reference 16 '. As can be seen from these figures, the edges W of the web 35 ίο 75381 1 are in the region of the transverse kaomlolden 31-37, where the pressure staggering shown in Figures 3 and 6 prevails. The longitudinal bellows chambers 31'-37 'remain in the area between the ends 16' of the roll and the edges W of the web, where the pressure grading is only relevant for the lining loads.

According to Figures 4 and 7, the chamber 34 of maximum pressure is divided into sub-chambers 34 ', in which an independently adjustable pressure prevails within the limits allowed by the gap 62. Em. in the figures these 10 pressures are denoted by the reference P4a »P4b» P4c »P4d and p5a, p5b, p5c’p5d *

Figures 1e do not show hydraulic pumps or palm air compressors or wiring for introducing different pressures into chambers 31-37, as these devices are, however, known to a person skilled in the art. Figures 15 also do not show control devices with which, in a centralized manner, different pressures are adjusted to provide a suitable longitudinal and / or transverse pressure profile in the different chambers. Naturally, these control devices are arranged in such a way that only those flange profiles are possible which are reasonable and feasible in terms of the durability of the seals and possibly also the wear.

According to Figures 1 and 2, the sector of the pressure zone is 20 °. In practice, the size of the sector oi can vary within very wide limits, e.g. between c * Ä 10 ° ... 60 °. The wider the sector, the longer the press-25 distance and the press start are obtained when a certain size of roller is used.

In general, in applying the method of the invention, a press having a wide spray zone has at least three consecutive bellows zones, of which a higher pressure is present in the middle pressure zone than in the outermost zones. When blankets 10 and 12 with a sufficiently large water transport capacity are used in the invention, it is possible to carry out the dewatering by pressing paper or board using only one sheet press using the method of the invention. In this case, the adjustability of the pressure profile is quite important.

The following are claims within the scope of which the various details of the invention may vary within the scope of the inventive idea.

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Claims (5)

A method for dewatering the eu peppers or cardboard web mechanically by pressing, which method is used in comparison with the area of a roll cut pin wide press zone (0) formed between a press roll (16) and a press shoe (20) acting against it. ), which press shoe (20) is positioned within an impermeable belt joint (14) and in which press shoe (20) it is used a pressurized pressurized chamber arrangement which borders on one screen to press shoe 10 (20) and on the web of the web ( W) pressed to said impermeable belt (14) and through which the pressing zone (o <) which is pressed (W) is guided in connection with a press tissue, most preferably between two press tissues (10, 12), which act as a means for transporting the web (V) forward and as means transporting worms out of the web (W) pressed water 15 and which press zone (^ 4) in the running section of the web (W) has been divided at least three times from each other and from the outside air by means of sealing means (51-60) isolated pressure chambers (31-37) which extends across the entire width of the web (W) over its entire width, characterized in that a full or nearly full pressure zone treatment pressure (ρρ, ρ <) is applied to the middle (34,35) or the middle of said pressure chambers. in contrast, to the outermost pressure chambers (31, 37), a pressure medium pressure (Pj 2 Py) which is substantially less than the full treatment pressure is conducted. 1 2 3 4 5 6 7 8 9 10 11 1 Patent claim 2. A method according to claim 1, characterized in that the pressure zone (© 4) is divided into several, preferably five to ten, of 3 seals (51-60) from each other and the outdoor air-cooled pressure chambers 4 (31-37), to said pressure chambers (31-37) are guided in the running direction of the web (W) incrementally (Δρ) etching pressure (p1 ^ «P ^₂P PP ^) to use the 16 chambers after the middle chamber (34.35) a step-by-step 7 (Δρ5, Δ Ρ6 »Δρ7» Αρ8) decreasing pressure and that the pressures (pj-p7) of the various chambers (31-37) and the stepping (Δρ.-Δρ there is obtained a shelf life and load for both the drainage and the sealing elements (51-58) advantage 11 pressure profile 1 in the press zone (© 4) (fig. 3 and 6).