FI116471B - Method and apparatus for cleaning tissue of a paper or board machine - Google Patents

Description

! 116471

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.

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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.

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Surgery of the aforementioned wire or felt, i.e. against tissue, is discussed e.g. Fl in U.S. Patent Nos. 87,813, Fl Patent Applications 970380 and 20011901; and U.S. Patent Nos. 5,512,136 and 5,879,515.

; Fl 87813 discloses a method for cutting a threading ribbon on a dryer section of a paper or board machine utilizing 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 has been 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 at the transverse shear, where 2 116471 material is collected. 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 headband starts from the situation where both dual-cutter cutting nozzles mounted on trolley-mounted wagons are parallel to one side of the track and the entire web goes straight down from the fabric to the pulper. Thereafter, a second 10 (track side) cutting nozzle starts to cut a strip at the edge of the web, which is blown onto the ropes, whereby the strip is further introduced, for example, into the rolls of the next drying section. This shear nozzle, together with the second shear nozzle, proceeds slowly to guide towards the center of the web, leaving a flat-blade headband between the shear nozzles and the second shear nozzle 15 beginning to cut off the edge of the web which is allowed to enter the pulper. In turn, as the cutting nozzles extend into the center of the web, the threading strap has moved approximately to the centerline of the rolls of the next drying section, whereupon spreading of the web can be started by uniformly moving each cutting nozzle away from each other. By doing this, the web can be spread evenly over, for example, the next 20 drying sections. However, it has now been found that, especially in the early stages of cutting the threading tape 1, where the flat edge is cut some distance from the edge of the web, the surface of the wire tends to become contaminated by cutting fibers and other web materials, possibly fillers and adhesives.

. ", It has also been found that conventional fabric washers with a washing function that is targeted to the same width of the wire cannot, under all circumstances, clean '·', these impurities coming from the same area.

* · * * *. FI-20011901 deals with a high pressure water assembly for a paper machine. In ;;; teaches how to place high pressure pumps at appropriate positions in connection with a paper machine, from which high pressure water is led to various applications, instead of previously having a high pressure pump for each high pressure water need.

US 5,512,136 deals with the removal of an edge strip from a wire on a wire section of a paper machine. 35 In the solution shown, a flat blade edge strip is cut with air blast at each edge of the web, followed by applying liquid jets of liquid from the nozzles on each side of the web 3 116471 across the width of the web, so that the webs are released from the web. The solution according to the publication is characterized in that the nozzle-bearing machine transverse nozzle beam is arranged in pairs so that the extreme nozzles 5 on the outer edge of the wire or web are connected, the next extreme in each direction and so on. These pairs of nozzles can then be actuated in the required amount so as to provide a strip removal jet with a cut edge strip width.

10 It is thus an air-blasting of a very wet and easily disintegrating web and the liquid-jet stripping of the web cut from that web. In such a case, air blasting mainly plows the groove on each side of the wet track, which separates the edge strips from the actual track. In our opinion, air blast does not blow fibers or other solids into the wire, but, as already mentioned above, blows 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 very low pressure liquid jet of about 5 bar is sufficient to remove the edge band.

20 New? No. 5,879,515 deals with contamination and cleaning of various conveyor belts and wires in a paper machine. The publication explains how to use; : Rotating nozzle for edge band cutting against wire, provides a smooth wave response, minimizing both wire stress in high pressure jets and wire contamination. Further, the publication teaches that the 25 rotating nozzles can also be used for fabric washing, whereby there is only a '··· need to change the fluid pressure used. However, the end result is that if the same nozzle is used for both cutting and wire cleaning, the liquid jets will always be on the same side and still in the same direction to the tissue, which is not * '! l! By no means is always the best way to wash wire.

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Using the same nozzle for both cutting and washing does not make sense in the same way: in practice, it is sensible to have a needle-like and sharp jet specifically designed for cutting, and for washing ...: a wider area and different a directional shower.

35 The orientation of the shower jet is important especially when washing is performed from the same side of the tissue as the incision. In this case, the material forced on the pores 4 116471 of the surgical jet must be removed from the pores by wash jets, which may not be in the same direction as the jet jets.

A major problem in apparatuses employing water jet cutting against papermaking machine tissue 5 is the partial occlusion of tissue at the intersection. This is because the high pressure water jet used in water jet cutting, especially in the drier areas of the paper or board machine, forces some of the cutting waste, which is fibers and fillers etc. into the tissue surface or to some extent inside the tissue. tissue. It has also been investigated how a conventional fabric washer, thus washing the entire width of the fabric, is effective on the tape trash debris. Here, it has been found that a conventional pressurized water-based tissue washer cannot remove more than a fraction of the surgical waste. This is probably because the pressure of the washing liquid used, because it is dimensioned with regard to conventional ways of soiling the tissue, is too low.

As a result of partial clogging of the tissue, the dewatering capacity of that tissue region is diminished, which in turn leads to an increase in moisture in the corresponding region of the web, which may further have its own 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.

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

. When surgical showers pack various solids, including 25 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.

; In addition, a vacuum roller for the drying section, above which is the washing system in some cases !! locates, tends to become clogged because, when the wire is being washed, the material discharged from the wire falls on the roll in question, at least partially blocking the roll grooves.

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., * The method and apparatus of the present invention overcomes 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 at least one of the many embodiments of the invention 5116471 - allows for fabric washing if desired from the opposite side to the cut, - uses the same pressure water source for both web cutting and fabric washing; - allows use of only one beam, - is more maintenance-friendly than prior art equipment when placed in a cooler space at the machine level, 10 - can be installed in existing cutters, and - cutting waste does not block the surface of the vacuum roll and .

In a preferred embodiment of the method of the invention for cleaning tissue from a paper or board machine, the operation of the water jet and said washing jet are timed together.

In another preferred embodiment of the method according to the invention, the paper: · ,, or paperboard machine for cleaning the web by watercutting against the tissue ”; the method of washing the scraps during cutting of the webs during the web breaks; from the same water cutting unit as the water used in the water cutting, it is characterized in that said cutting waste is removed from the tissue substantially to the width of the cutting waste, with several washing jets extending from the same nozzle 30 to the cutting nozzle.

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For an apparatus according to an advantageous embodiment of the invention for cleaning the tissue of a paper or board machine from a cutting waste generated by cutting water on the web against the tissue, the apparatus includes at least one 35 that at least one tissue wash nozzle for removing debris from the tissue and means for introducing wash water to the wash nozzle are disposed adjacent said tissue in the downstream direction of said tissue nozzle.

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An apparatus for cleaning a tissue of a paper or board machine in accordance with another preferred embodiment of the invention, , is characterized in that a separate washing nozzle unit is provided on the same beam as the cutting nozzle to remove the debris from the tissue.

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

In the following, the method according to the invention will be explained in more detail with reference to the accompanying figures, of which Figure 1 illustrates by way of example an apparatus arrangement according to a preferred embodiment m of the invention, Figure 2 illustrates another preferred embodiment of the invention; Figure 3 illustrates, by way of example, an apparatus arrangement according to a third preferred embodiment of the invention, and Figure 4 shows in greater detail a washing nozzle arrangement according to the embodiment shown in Figure 3.

*!;! Figure 1 illustrates an apparatus * »I f '; * 30 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 .... {an example of a dryer section of a paper machine consisting of a plurality of vacuum rollers 10 and steam cylinders 10 '.

In the figure, the track 14 comes from the left and continues to the right as the drying wire 12 wraps around the cylinder group, e.g. through roll 16.

i · 7 116471

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 may be of any known or new type. It is essential for the invention only that the surgery is performed with one or more high pressure water jets against the tissue. The nozzle 22 of the water cutter 20 receives its pressurized water from the water cutting unit 24, from which the water cutter 20 is supplied with one or more pressure water pipes 26. In practice, the cutting takes place at very high pressure, which depending on the distance of the nozzle from the track, it can range from 10 to a few tens of bars (about 30 to 50) up to 600 to 800 bar. However, the end result of the cut is not only a strip cut off the actual web, but also a soiled area of a few millimeters up to about ten millimeters wide in a wire that is nearly clogged with trimmings.

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Fig. 1 further shows, by reference numeral 30, a wire washing apparatus according to a preferred 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 into which the washing water has penetrated through the wire and 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.

• 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 pipe 36. Pipes 26 and 36 leave water cutting unit 24 via solenoid valves to control water supply to cutting and washing nozzles 22 and 32.

: '1': Of course, it is preferable to direct the water supply to the shear nozzles 22 to start slightly 1.30 prior to engaging the wash nozzles 32 due to the distance between the shear and wash nozzles in the direction of travel of the web 14. However, this is not necessary, because * spraying the washing water on the wire shortly before the cutting waste has been left • ': the nozzles 32 do not matter - even the water consumption is not significant because the amount of water required is very small. More important for controlling the use of water 35 is to allow the wire washing operation to continue for some time, at least for a time corresponding to the distance between the cutting and washing nozzles, after completion of 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 the pressure of the cutting nozzle, i.e. in the order of 60 to 800 bar, preferably 200 to 400 bar. The width of the shower jet is preferably dimensioned slightly wider than the contaminated area left by the cutting jet so that the width of the shower jet is in the order of 5-20 millimeters. The width of the wash jet is achieved either by arranging a nozzle which becomes a needle-like jet at a suitable distance from the wire or by using a nozzle having a conical or flat jet shape. In the latter two cases, the nozzle 10 can be placed closer to the wire, so that the distance is in the order of 20 to 50 mm. In the case of a nozzle giving a needle-like shower, a suitable cleaning distance, in turn, is 130 to 150 mm, whereby the shower remains needle-like at a distance of about 50 to 80 mm from the nozzle and then spreads about 20 mm wide.

Figure 2 illustrates a solution according to another preferred embodiment of the invention, which otherwise corresponds to that of Figure 1, but in this embodiment, water to the wash nozzle conduit 36 'is drawn directly from the shear nozzle conduit 26' via 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 both starts and turns off simultaneously. The '*' 'is then operated by the ^ 1 solenoid valve 1 * ^:' * in connection with the water cutting unit 24 per pair of nozzles. However, the drawback is that the wire will stop washing before ... ... · 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 have also found that, in some cases, it is preferable for X 30 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 test '1 substantially enhanced the purification.

35 The apparatus of the above embodiments is characterized in that it can be placed in any position suitable for a paper or board machine, either on 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 water jet cutting against the wire, whereby it is advantageous that the wire washing equipment is preferably located as close as possible to the cutting point on the opposite side of the wire. However, for example, with the drying section, as in the exemplary embodiments described above, the mutual arrangement of the various sections may require that the water cutter 20 be arranged between space and the wire washing apparatus 30 only after the folding roll 16 following the last drying cylinder 10 '. upper circulation.

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Figure 3 illustrates very schematically a solution according to a third preferred embodiment of the invention, which can also be placed anywhere on a paper or board machine, as is the case with the devices according to the previous embodiments. The difference, however, is that the scrubbers of this embodiment are located in connection with the cutting nozzles 15 at the machine level away from the top of the hood from the level of the steam cylinders. In the embodiment of this figure, the washing nozzle (s) 42 are provided on the same beam 40 with the cutting nozzle 22 nozzles 22 '. Otherwise, the washing nozzles 42 operate in substantially the same manner as in the previous embodiments. However, since the washing nozzle unit 42 can advantageously be even in the same nozzle arm 20 with the cutting nozzle 22 ", the washing nozzle unit 42 cannot be operated at the same time with the cutting nozzle: 22" because the web passing through the wire would be broken. In other words, the washing of the wire in this embodiment can only take place during web breaks.

In the solution according to this embodiment, the wire is cleaned in such a way that, for example, the cutting of the threading strap is carried out by means of one or two cutting nozzles: 22 ", as previously described in this specification. Similarly, the edge strip is cut as described above. However, since in this embodiment ·· the washing apparatus is arranged on the part of the wire where the web passes with the wire, the wire cannot be washed while the machine is being manufactured, but only for some reason or another, the wire is cut off.

In practice, the apparatus illustrated in Fig. 3 operates such that the shear nozzles 22 "are used both at the time of threading and at the edge strip. The shear nozzles 22" are movable along the beam 40 in the conventional manner. 35 On the opposite side of the wire a trough 44 which may be inclined either from one side of the machine to the other side of the machine or from the center of the machine to both sides. Preferably, flushing means are provided in connection with the trough 44 for flushing out any waste from the trough which is collected in the trough. The trough 44 prevents cutting debris from reaching the surface of the vacuum roll 10, which is a disadvantage of many prior art devices 5. The figure further shows the suction box shown at 48 for detaching the web from the surface of the steam cylinder 10 '. The aforementioned trough 44 may be supported, for example, on the side wall of the suction box 48.

Reference numeral 42 represents a washing nozzle assembly preferably located on the same nozzle arm 10 (shown in more detail in Figure 4) with the cutting nozzles 22 '. However, there is nothing to prevent the washing nozzles from being positioned on their arm and also on their own trolley on the beam 40 if it is deemed necessary for one reason or another. It is still most advantageous to arrange the washing nozzle assembly 42 with respect to the cutting nozzles 22 'so that the same trough 44 can be used to remove dirt and debris during both web cutting and wire washing. However, if said washing nozzle unit 42 and shear nozzles 22 "are located relatively far apart in the direction of movement of the wire, it is necessary to arrange two troughs or to extend the trough accordingly in the direction of movement of the web so that it can collect dirt and cutting debris through the wire.

Fig. 4 shows in greater detail the v 'washing nozzle unit 42 according to the embodiment shown in Fig. 3. The nozzle assembly 42 is in fact worn by several nozzles:' ·· (six pieces in the figure, may vary from 2 to 10 depending on application) the shower has the same shape or orientation, or * 25 different in shape. In the solution of the figure, the washing nozzle assembly 42 is mounted on the same nozzle arm 46 adjacent to the cutting nozzle 22 'so that the same trough can be used to collect dirt and debris during both cutting and washing. At its lower end, the nozzle arm 46; i1 is secured to a plate 50 by means of which the nozzle arm 46 is secured to the beam: In addition, Fig. 4 shows a water pipe 26 "for shear water and a water pipe 56 for washing water. Both shear water and wash water are brought from the same a 1 ·. '!! from the water cutting unit as in previous embodiments. Also quite previous

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In accordance with embodiments, either solenoid valves or the like, which control the operation of the ':': nozzles are provided in connection with either the water cutting unit or the '· water pipes leading to the nozzles.

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The foregoing has not, in all embodiments, determined whether the cutting and washing nozzles 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 may be either fixed or movable. It is even conceivable that the wash nozzle nozzles are arranged to be displaced laterally on the wire in the same manner as the nozzle cutting nozzles. 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 way to facilitate synchronization is, of course, to change the width of the wash jet, whereby the jet width compensates for any slight difference in the timing of the nozzle operation.

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As seen from the foregoing, a new fabric washing apparatus has been developed which is capable of releasing efficiently and reliably the folded and penetrated fibers and other papermaking solids from the fabric by means of a high pressure liquid jet. From the foregoing description of the invention, it should be noted that the invention has been described therein in light of only a few exemplary and schematic embodiments. Thus, it is clear that the invention may depart significantly from the foregoing, while remaining within the scope of the appended claims.

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Claims (26)

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) by a washing jet extending ) 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 for cleaning tissue of a paper or board machine by cutting the web (14) from the cutting debris generated by cutting the web (12) against the web (12), wherein the web is washed during the web breaks with a washing spray on the same side of the fabric (12). 24) water used for water cutting, characterized in that said cutting waste is removed from the tissue (12) by a plurality of washing jets extending substantially across the width of the cutting waste, the nozzles of which are located on the same arm (46) with the cutting nozzle (22 "). 20 Method according to Claim 2, characterized in that the fabric (12) is washed by spraying pressure water with different directions and / or different jets in the area of the cutting waste. • ·, * ··. The method according to claim 1 or 2, characterized in that said washing jet is a high pressure water jet. A method according to claim 4, characterized in that the method according to claim 4. . the water jet pressure is 30 - 800 bar. 3o • · • » 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. * * », ·. A method according to claim 1 or 2, characterized in that said washing jet is movable laterally. , 3 1 1 6471 A method according to claim 1, characterized in that said washing jet is started with a delay after starting the cutting jet. Method according to claim 8, characterized in that said delay 5 corresponds substantially to the distance of the jets in the direction of movement of the fabric (12). A method according to claim 1, characterized in that said wash jet is switched off after said delay from the cut off of the cutting jet. 10 A method according to claim 1, characterized in that said cutting waste removal is assisted by an air jet. Apparatus for cleaning tissue of a paper or board machine by cutting water debris (15) against the web (12) by cutting at least one water cutting nozzle (22, 22 ') and a water cutting unit (24) for producing pressurized water to said cutting nozzle (14). ) and a flow tube (26, 26 ') connecting said unit (24) and said nozzle (22, 22'), characterized in that at least 20 at least 20 cutting nozzles (22, 22 ') are disposed in connection with said tissue (12) one fabric washing nozzle (32, 32 ') for removing 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). 116471 for easier removal. Apparatus for cleaning paper or board machine fabric by cutting water from the web (14) by cutting water from the web (12), comprising at least one water cutting nozzle (22 ") arranged in a transverse beam mounted carriage (46) and for supplying pressurized water to said shear nozzle (22 ") and a flow pipe (26") connecting said unit (24) to said nozzle (22 "), characterized in that 10 separate washing nozzle units (42) are provided on the same beam (40). ) for removing surgical debris from tissue (12). Apparatus according to Claim 17, characterized in that both the cutting nozzle (22 "), the fabric washing nozzle unit (42) and also the partially flow tube (56) for supplying the washing nozzle unit (42) from the water cutting unit (24) are arranged in said shaft (46). Apparatus according to claim 12 or 17, characterized in that at least one trough (34, 44) is provided operably connected to said washing nozzle (32, 32 ', 42) for collecting washing water and cutting waste. : 20 " 20. Apparatus according to claim 12 or 17, characterized in that the 'water cutting unit (24) is provided with means for timing both the cutting and washing jets. «* Apparatus according to claim 12 or 17, characterized in that the flow pipes (26 ', 36'; 26 ", 56) or the nozzles (22 ', 32'; 22", 42) associated therewith are provided with devices for both cutting and to schedule shower showers. k · »» Apparatus according to claim 19 or 20, characterized in that said timing devices are solenoid valves. * · Apparatus according to claim 12 or 17, characterized in that 'at least one washing nozzle (32, 32') is located on a wire or press section of a papermaking machine: a winder, a rewinder, a sheet cutter, between different roll groups 35 of a drying section, or . 116471 Apparatus according to Claim 17, characterized in that said nozzle assembly (42) consists of a plurality of nozzles of at least two different types. Apparatus according to claim 17, characterized in that some of the nozzles are needle nozzles and some are fan nozzles. Apparatus according to claim 17, characterized in that the nozzles are directed in at least two different directions. J I · I · * »• * *» * »» · <* 116471