FI114487B - Procedures and devices for cleaning the tissue of a paper or cardboard machine - Google Patents

Description

1 114487

Method and apparatus for cleaning tissue of a paper or board machine

The present invention relates to a method and apparatus for cleaning tissue of a paper or board machine. The method and apparatus of the invention are well suited for use in tissue cleaning of a paper or board machine in cases where, for example, an edge band or a threading strap is cut against the tissue. Particularly preferably, the method and apparatus of the invention are used on the dry end of a paper or board machine, i.e., parts of a paper or board machine after the wire and press section.

10

In a paper or board machine, the fibrous web, also referred to as the web, is cut at various points into a strip, which is most often removed to a pulper through which the fibrous material is recycled. An example of such objects is edge band cutting, which aims to adjust the width of the web to the width of 15 already reasonably well finished products. The edge strips are cut with a wire or press section of a papermaking machine, with winders, a rewind machine and sheet cutters. Another object is, for example, cuts in the threading strips between the different roll groups of the dryer section or the cylinder drying sections of the on-machine coating machines.

20 There are many types of surgery for these purposes, but recently, pressure water surgery has become increasingly popular. Most popular is the method of cutting in which the web is cut against a wire or felt, for example, either a drying wire or a press felt, more generally against the tissue of a paper or board machine.

25th ·. Surgery of the aforementioned wire or felt, i.e. against tissue, is discussed e.g. Fl, in U.S. Patent Nos. 87813, F1, 970380 and 20011901,, and U.S. Patent Nos. 5,512,136 and 5,879,515.

*> 30 Fl 87813 deals with a method for cutting a threading tape in paper or * i t: '. using a pressurized water jet. It is stated in the publication that the strip is cut against a dryer wire at a pressure of 40 to 400 bar. Although it is stated in the publication that the water jet carries: * '': the fibers that have been detached from the intersection, this is practically not entirely correct, but the wire has been found to collect fibers, especially more to the same point on the wire.

Fl application 970380 relates to a method and apparatus for forming a threading tape in a paper or board machine. The publication discloses a special 5 double cutter for cutting the threading strap. In the solution according to the publication, the cutting of the threading strap starts from the situation where the two cutting nozzles of the twin cutters are parallel to one side of the track and the entire web goes straight down from the fabric to the pulper. Thereafter, a second (track side) cutter is used to cut a band at the edge of the track, which is blown onto the ropes, whereby the band is further introduced, for example, into the rolls of the next drying section. The cutter in question, together with the second cutting nozzle, proceeds slowly towards the center of the web, leaving a flat-blade headband between the cutter and the other cutter beginning to cut the web at the edge of the web, which is allowed to enter the pulper. In turn, as the cutters advance to the center of the web, the threading strap has moved approximately to the centerline of the rolls of the next drying section, whereby the spreading of the web can be started by uniformly moving both cutters away from each other. By doing this, the web can be spread evenly over the next drying section, for example. However, it has now been found that, especially in the early stages of threading of the threading strip, where the strip is cut some 20 distances from flat strips, the surface of the wire tends to get dirty because the cutting nozzles:! *: blowing both fibers and other substances in the web, possibly with fillers; adhesives, etc. It has also been found that ordinary wire washers, which; y the washing function simultaneously applies to the entire width of the wire, not all of them. '·. conditions to clean up these contaminants coming to the same spot on the wire.

25th · ·. FI-20011901 deals with a high pressure water assembly for a paper machine. <· F teaches how to set up high pressure pumps at appropriate positions,>, in connection with a paper machine, from which high pressure water is led to various applications I * ··. instead of previously having a high-pressure pump for each site that needs high-pressure water * y 30.

US 5,512,136 deals with the removal of an edge strip from a wire on a wire section of a papermaking machine.

: * ·, · In the solution shown, a flat blade is cut at each edge of the web by air blasting, followed by applying liquid jets of liquid from the nozzles on each side of the web to the width of the web, so that the webs are released. The solution of the publication is characterized in that the nozzle-bearing nozzle beam is provided with pairs of nozzles, so that the extreme nozzles on the outer edge of the wire or web are connected, the second extreme from each direction, and so on. These pairs of nozzles can then be actuated in the required amount so as to provide a strip-off jet of cut-off 5-band width.

It is thus an air blasting of a very wet and easily degradable web and a liquid jet removal of the web cut from that web. In such a case, air blasting essentially plows each groove 10 on the wet track, which separates the edge strips from the actual track. In our opinion, air blast does not blow fibers or other solids inside the wire, but, as stated above, plows them to the sides. After the cut, the actual web is introduced into the press section of the papermaking machine in a known manner and the edge strip is removed from the wire by a wire return cycle to the pulper below. A low-pressure liquid jet of about 15 bar, 5 bar, is sufficient to remove the edge band.

US 5,879,515 deals with contamination and cleaning of various conveyor belts and wires in a paper machine. The publication discloses how to use a rotating nozzle to cut an edge strip against a wire to achieve a smooth 20-wave cut, thereby minimizing both the strain on the wire in high-pressure jets and the fouling of the wire. The publication also teaches: Y; the rotary nozzle can also be used for washing the fabric, whereby there is only a need to change the fluid pressure used. However, the end result is that if the same device is used for both cutting and wire cleaning, the liquid jets will always be on the same side of the tissue, which is not always the best way. · · ·, In wire washing.

A major problem with water jet cutting paper machine fabric '··' has been found to be a partial clogging of the tissue at the Y 30 intersection. This is because the high-pressure water jet used in water jet cutting, especially in the drier areas of paper or paperboard machines, forces * ...: some of the cutting waste, which is fibers and fillers etc. to the surface of the fabric or to some extent inside the fabric. the tissue function is no longer the same as in other parts of the tissue. It has also been investigated how a conventional 35-tissue washer, thus washing the entire width of the fabric, is effective on the tape trash debris. Here, it has been found that a conventional tissue-water-based pressure washer 4,414,487 is capable of removing only a fraction of the cutting waste.

This is probably because the pressure of the washing liquid used, because it is dimensioned in terms of the conventional ways of soiling the tissue, is too low.

5 Partial clogging of the tissue results in a dehydration of the area of the tissue, which in turn leads to an increase in the moisture content of the corresponding area of the web, which may further have an effect on the quality of the final product. For example, it is possible that the basis weight of the product decreases at the edges of the web when the edge strip cutting debris is not effectively removed from the tissue.

10

Another problem may also be the strain on the tissue itself in the above paragraph.

When surgical jets are used to pack various solids, including different coatings and / or adhesives, into the tissue, the physical properties of the tissue change over time, rendering the tissue inhomogeneous and stressing the tissue.

15

The method and apparatus of the present invention eliminate at least some of the problems of the prior art presented above.

Among the advantages of the invention, it is worth mentioning, inter alia, that the invention 20 - allows the tissue to be washed if desired with respect to surgery; 'j'; on the opposite side, - uses the same source of pressure water for both track cutting and tissue. for washing, and. · *. - spray a very narrow jet of wash water at just the right point of the tissue: ·, ·. 25 blowing out the surgical debris from the tissue.

»· # $

For the process of the invention, the tissue of a paper or board machine. to clean the web by cutting the water against the tissue while cutting !!! characterized in that said cutting waste is removed from the tissue by means of a washing jet extending substantially to the width of the cutting waste, that the pressurized water: said water jet is taken from the same water cutting unit as: water used for water cutting and water jet used for water cutting. \: the operation of said shower jet is timed together.

»I

The apparatus for cleaning the tissue of a paper or board machine according to the invention from cutting waste generated by cutting the web against the tissue, the apparatus comprising at least one water cutting nozzle and a water cutting unit for producing pressure water after the cutting nozzle, at least one tissue washing nozzle is disposed to remove the cutting debris from the tissue and to provide washing water to the washing nozzle.

Other features specific to the method and apparatus of the invention will be apparent from the appended claims.

10

In the following, the method of the invention will be explained in more detail with reference to the accompanying drawings, in which Figure 1 illustrates an apparatus arrangement according to a preferred embodiment of the invention, and Figure 2 illustrates an apparatus arrangement according to another preferred embodiment of the invention.

Figure 1 shows an apparatus according to a preferred embodiment of the invention arranged in connection with a drying section of a paper or board machine. For a more detailed construction of a paper or board machine, reference is made to the prior art publications. The embodiment of the figure shows a plurality of drying cylinders 10 and 10 'around which the drying wire 12 and the web 14 rotate.

: Y: In the figure, the track 14 comes from the left and continues to the right as the drying wire 12 turns: “*; around the cylinder group e.g. through roll 16.

25

In the figure, reference numeral 20 shows a water cutter for cutting, for example, a threading strap. The water cutter may be of the type described above in the prior art, or,. it can be of any known or new type. It is essential to the invention only that the cutting is performed with one or more high pressure water jets 30 against the tissue. The nozzle 22 of the water cutter 20 receives its pressurized water from the water cutting unit 24 from which one or more pressurized water pipes 26 at high pressure, which: * *: Depending on factors such as the distance of the nozzle from the track, it can vary from a few dozen bars (about 30-50) up to 600-800 bar.

• »· 35 However, the end result of the cutting is not only a strip cut off the actual web, but also a soiled area of a few millimeters up to about 10 millimeters 6 114487 in a wire that is nearly clogged with trimmings.

Figure 1 further illustrates with reference numeral 30 a wire washing apparatus according to an advantageous embodiment of the invention comprising one or more washing nozzles 32 and at least a trough 34 disposed on the opposite side of the wire to the washing water and fibers removed by the wire and other impurities. If necessary, a second trough can be placed below the wash nozzles on the same side of the wire to receive water and the like.

10 splashes. According to the figure, the washing apparatus 30 is preferably located on the opposite side of the wire to the cutting apparatus 20, whereby the washing takes place in the opposite direction to the wire contamination. The washing apparatus 30 receives the washing water from the water cutting unit 24 along the pipes 36. Pipes 26 and 36 leave water cutting unit 24 via solenoid valves to control water supply 15 to cutting and washing nozzles 22 and 32.

Of course, it is advantageous to direct the water supply to the shear nozzles 22 just before the wash nozzles 32 are engaged, due to the distance between the shear and wash nozzles in the direction of travel of the web 14. However, this is not necessary, since spraying 20 washes on the wire shortly before the cutting waste is discharged: *:: The nozzles 32 do not hurt - even the water consumption is not significant,:; ; because the amount of water needed is very small. More important to control the use of water is to allow the wire washing operation to continue for some time, at least after a corresponding delay between the cutting "*; and the washing nozzles, after completion of the cutting, so that all cutting waste is discharged from the wire.

The pressure of the wash jet is preferably, but not necessarily, substantially the same as; pressure of the shear nozzle, i.e. in the range of 60 to 800 bar. The width of the shower jet is dimensioned, ·· *. preferably slightly wider than the contaminated area left by the cutting shower, so that the width of the wash jet is in the order of 5 to 20 millimeters. The width of the shower jet is made '' 'either by arranging a nozzle that becomes a needle-like shower at a suitable distance from the wire or by using a nozzle having the shape of a shower:' *, i tapered or flat. In the latter two cases, the nozzle may be positioned: ': closer to the wire. In the case of a nozzle having a needle-like jet 35, a suitable cleaning distance is 130 to 150 mm, whereby the jet will remain needle-like at a distance of about 50 to 80 mm from the nozzle and then spread about 20 mm wide.

7 114487

Fig. 2 shows a solution according to another preferred embodiment of the invention, which otherwise corresponds to the solution of Fig. 1, but in this embodiment water is taken directly to the cutting nozzle pipe 26 'directly from the cutting nozzle pipe 26' by means of a T-branch piece 38.

In its simplest form, the apparatus of Fig. 2 operates in such a way that the strip cutting and wire washing function are both activated and deactivated simultaneously. This is accomplished by a single solenoid valve 10 in connection with the water cutting unit 24 per pair of nozzles. However, the drawback is that the wire cleaning stops even before the dirty part of the wire has been completely washed. This drawback is easily remedied by providing solenoid valves on each of the pipe legs 26 'and 36' or, for example, in connection with the nozzles 22 'and 32', whereby the operation of the nozzles can be timed to optimize.

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Studies carried out have also found that in some cases it is advantageous to provide an air nozzle above the scrub nozzle 32 or 32 'which is substantially aligned with the scrub nozzle. However, the pressure of the air nozzle need not be very high, for example the pressure of 6 bar used in experiment 20 substantially enhanced the purification.

,. '. The apparatus of the two embodiments described above is characterized in that it can ... be placed in any position suitable for a paper or board machine, ···, on either a wire section, a press section, a drying section, a winder, a rewinder or a sheet cutter. It is also characteristic that the cutting of the web takes place as a jet of water against the wire, whereby it is preferable that the washing equipment of the wire is placed on the opposite side of the wire, preferably as close as possible to the cutting point. However, for example, with a drying section such as the ones described above; in the exemplary embodiments, the interleaving of the various parts may **; * '30 require that the water cutter 20 be tracked for space issues between the last two drying cylinders and the wire washing apparatus 30 only the last drying cylinders 10', t, * after the next folding roll 16, the wire 12 leaves the so-called. upper circulation.

, ··, It has not been stated above whether the cutting and washing nozzles 35 described above are fixed or movable. This is not necessary as such, as they can in principle be of either type. In other words, the nozzles can be either 8 114487 fixed or movable. It is even conceivable that the wash nozzle (s) are arranged to be displaced laterally on the wire in the same manner as the threading nozzles of the thread. In this case, the movement of the washing nozzles should be well synchronized with the movement of the cutting nozzles so that they wash in the correct area of the wire. One of the 5 ways to facilitate synchronization is, of course, changing the width of the shower jet, whereby the jet width compensates for any slight difference in the timing of the nozzle operation.

As seen above, a new fabric washing apparatus has been developed which can effectively and reliably remove fibers and other papermaking solids adhered to and entrained in the fabric by a high pressure liquid jet. From the foregoing description of the invention, it should be noted that the invention has been described in the light of only two exemplary and schematic embodiments. Thus, it is clear that the invention may depart significantly from the foregoing, while remaining within the scope defined by the appended claims.

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Claims (19)

A process for cleaning a tissue of a paper or board machine by cutting the web (14) from the cutting waste produced by cutting the web (12) against the web (12), characterized in that said cutting waste is removed from the fabric (12) ) other than water used for water cutting and that the water jet used for water cutting and said shower jet are timed together. 10 A method according to claim 1, characterized in that said washing jet is a high pressure water jet. Method according to claim 2, characterized in that said water jet pressure is 30 to 800 bar. A method according to claim 1, characterized in that said washing jet is disposed on the opposite side of the tissue (12) to the cutting jet. 20 '5. A method according to claim 1, characterized in that said washing jet is movable laterally. »· • ·. A method according to claim 1, characterized in that said. v. 25 The shower jet is started with a delay after the shower jet starts. 1 »> * * t A method according to claim 6, characterized in that said delay substantially corresponds to the distance of the jets in the direction of movement of the fabric (12). * »» »» I »* *: * '30 A method according to claim 1, characterized in that said jet: jet is switched off after said delay from the cut off of the shear jet. • ·. ·. A method according to claim 1, characterized in that said t | | »I. * · ·, The air jet is used to assist in the removal of trimmings. »I 9 114487 Apparatus for cleaning tissue of a paper or board machine by means of a water cutting of the web (14) 35 to 14447 water cutting from the tissue (12), including at least one water cutting nozzle (22, 22 ') and a water cutting unit (24) for supplying pressurized water 22, 22 ') and a flow tube (26, 26') connecting said unit (24) and said nozzle (22, 22 '), characterized in that said cutting nozzle (22, 22') is connected to said tissue (12) in the direction of tissue travel. thereafter, at least one fabric washing nozzle (32, 32 ') is disposed to remove cutting debris from the fabric (12) and a flow tube (36, 36') for supplying washing water to the washing nozzle (32, 32 ') from the water cutting unit (24). Apparatus according to claim 10, characterized in that said at least one tissue washing nozzle (32, 32 ') is a high pressure nozzle. Apparatus according to claim 10, characterized in that said washing nozzle (32, 32 ') is located laterally at substantially the same position as the cutting nozzle (22, 22') of the tissue 15 (12). Apparatus according to claim 10, characterized in that said washing nozzle (32, 32 ') is located opposite to said cutting nozzle (22, 22') on the opposite side of the fabric (12). 20 Apparatus according to Claim 10, characterized in that air is blown in connection with said; Y: washing nozzle (32, 32 '); '. to facilitate removal. * ·> I I v. 25 Apparatus according to claim 10, characterized in that said apparatus. · · ·. at least one trough (34) is provided in connection with the washing nozzle (32, 323 ') for collecting the washing water and I t * cutting waste. *> · 'Y, Apparatus according to claim 10, characterized in that the »» Y 30 water cutting unit (24) is provided with devices for both cutting and washing jets:. for scheduling. ; *; Apparatus according to claim 10, characterized in that; 1 ''. the flow pipes (26 ', 36') or the nozzles (22 ', 32') associated therewith are provided with means 35 for scheduling both cutting and washing jets. u 114487 Apparatus according to claim 16 or 17, characterized in that said timing devices are solenoid valves. Apparatus according to claim 10, characterized in that said at least one washing nozzle (32, 32 ') is located on a wire or press section of a papermaking machine, a winder, a rewinding machine, a sheet cutter, between different roll groups of a drying section or cylinder drying parts of on-machine coaters. * »*» I »1 • t * *» »12 1 1 4487