WO2000053846A1

WO2000053846A1 - Cleaning device

Info

Publication number: WO2000053846A1
Application number: PCT/FI2000/000163
Authority: WO
Inventors: Esa KOTIMÄKI; Reijo Ruottu; Paavo Sairanen; Heikki Truhponen
Original assignee: Metso Paper, Inc.
Priority date: 1999-03-05
Filing date: 2000-03-02
Publication date: 2000-09-14
Also published as: AU2919700A; FI3977U1; FIU990105U0

Abstract

A device for cleaning a suction roll. The device comprises a distribution box (1), to which at least one nozzle row (2) is connected parallel to the axis of the suction roll (9). The nozzles are needle nozzles. Further the device copmrises means (4, 5) for moving the distribution box (1) over the surface of the suction roll, and means (6, 7) for supplying cleaning medium at pressure into the distribution box. The device further comprises means (8) for aligning the nozzles (3) with the holes (11) of the suction roll to be cleaned.

Description

Cleaning device

The invention relates to a device according to the introductory part of the independent claim presented below for cleaning a suction roll, particularly to a device which comprises a distribution box and connected to it at least one nozzle row substantially parallel with the axis of the suction roll to be cleaned. Further the cleaning device has means for moving the distribution box over the surface of the suction roll to be cleaned and for supplying a cleaning medium at a pressure into the distribution box.

From the Finnish utility model 3529 there is known a washing equipment intended for the cleaning of rolls used in the paper industry. In this washing equipment washing liquid is sprayed at a high-pressure against the outer surface of the roll to be washed. The high-pressure nozzles are connected to a high pressure generator being able to generate a pressure of at least 150 bar, and the hole size of the high- pressure nozzles is at most 2 mm. The high pressure nozzles are located in a row in a nozzle structure which is moved in the direction of the roll's axis, so that the roll can be washed from end to end. During washing the nozzle structure is stationary as the roll to be washed is rotated.

A better washing result than ever before, with a lower water consumption, has been achieved with the above mentioned known washing equipment when the washing water is sprayed as a jet with well defined borders and at a high pressure against the surface of the roll to be washed.

The object of the present invention is to provide a device intended particularly for the cleaning of suction rolls. The suction rolls used in the paper industry are perforated rolls with a negative pressure prevailing within them, for instance a negative pressure created by a suction box. The suction rolls are used together with a wire or a felt, whereby the suction ensures that the paper web is kept on or transferred onto the wire or felt. Therefore, it is very important that the holes in the suction roll should not get clogged during use, and these suction rolls must be cleaned from time to time, as with time dirt is accumulated on the surface of the suction roll and particularly in the holes.

An object of the present invention is particularly to provide a device for cleaning a grooved suction roll. In a grooved suction roll the suction holes are located in grooves encircling the outer surface of the roll, in which case it is particularly cumbersome to clean the holes at the bottom of such grooves.

Thus the object of the present invention is to provide a device for cleaning a suction roll, and particularly a grooved suction roll used in the paper industry, with the aid of a cleaning medium, such as steam, a liquid, or air. When using steam and washing water it is desirable that a minimum amount of water is left by the washing, which water must be removed after the washing in any case. Thus the object of the present invention is to provide a device for cleaning a suction roll and particularly a grooved suction roll, where a minimum amount of water is required to provide a good washing result and where the required washing time is as short as possible.

In order to achieve the above mentioned objects a device according to the invention is characterised in what is defined in the characterising clause of the first claim presented below.

According to the invention the cleaning effect of the cleaning device is according to the invention based on the fact, that the needle nozzles or the like can be very precisely directed against the holes of the suction roll to be cleaned.

The nozzles used in the cleaning device according to the invention are needle nozzles or the like known per se, having a hole size which preferably is at most about 4 mm, e.g. about 1 to 3 mm.

As the suction roll to be cleaned is very wide compared with the distribution box used in the cleaning device according to the invention, the distribution box must be moved as the washing proceeds in the direction of the axis of the suction roll to be cleaned. Advantageously the distribution box is located outside the suction roll to be cleaned, where the maintenance of the distribution box is easier.

Further the needle nozzles in the needle nozzle row of the distribution box are advantageously located at a distance from each other in the direction of the axis of the suction roll, the distance being defined by the holes in the suction roll, so that all holes over the length of the distribution box can be cleaned during one revolution of the suction roll. Then cleaning medium is advantageously sprayed, when a hole in the suction roll is located at a needle nozzle, whereby the rotational motion of the suction roll is advantageously stopped during the spraying.

In order to provide a washing effect which is as effective as possible the distribution box can be advantageously turned around its longitudinal axis, so that the needle nozzles are parallel to the radius of the suction roll to be cleaned, i.e. parallel to the holes in the suction roll.

A washing device according to the invention is particularly well suited for cleaning a grooved suction roll where the holes open up into the bottom of the grooves encircling the suction roll. In such suction rolls, it is of particular importance that the needle nozzles can be aligned with the holes at the bottom of the grooves in the grooved suction roll to be cleaned, and to this end, in an advantageous embodiment of the invention, a runner or the like is fastened in the distribution box and pivoted on an axis parallel to the axis of the grooved suction roll to be cleaned, which the runner's peripheral part fits into the grooves of the grooved suction roll to be cleaned. When the runner rolls in a groove, each needle nozzle of the distribution box is reliably at the location of its own groove, which ensures that the cleaning medium jet reliably hits the holes at the bottom of each groove. Thus the needle nozzles in the axial needle nozzle row are located at a distance from each other, which distance advantageously is defined by the grooves in the grooved suction roll to be cleaned. This way also grooves without holes can be cleaned.

Steam, a liquid such as water, and/or air can be used as cleaning medium. It is essential that the means for supplying the cleaning medium at a pressure into the distribution box are able to create a sufficient pressure even at the needle nozzles, and that this sufficient pressure varies according to the cleaning medium used. When steam is used a pressure of at least about 3 bar is created in the needle nozzles, advantageously about 4 to 6 bar; when a cleaning liquid such as water is used there is created a pressure of at least about 100 bar in the needle nozzles, advantageously 100 to 150 bar; and when air is used the pressure is at least about 4 bar, advantageously over 6 bar.

Accumulated dirt must be cleaned by steam and/or water, but dust and lint can be easily cleaned by only air, so that no water is left after the cleaning. The means for moving the distribution box over the surface of the suction roll to be cleaned are advantageously arranged to move the distribution box substantially in the direction of the nozzle row, i.e. generally mainly parallel to the axis of the suction roll to be cleaned.

The movement of the distribution box over the suction roll to be cleaned can be accomplished in many ways, for instance, by wheels which are pivoted in the distribution box and which move along a rail in parallel with the axis of the suction roll, so that supported on the wheels the distribution box can be moved along the rail. The movement can be achieved mechanically or manually by pulling wires, which are fastened to the distribution box. There are advantageously a number of consecutive nozzle rows in the distribution box, in which case the needle nozzles in the consecutive nozzle rows can be axially displaced to the side regarding each other.

Thus, the function of the present cleaning device is based on the fact, that an precisely defined jet of cleaning medium is directed, at such a high pressure and for such a long time or so many times, against the holes in the suction roll and particularly against the holes at the bottom of the grooves in a grooved suction roll that dirt present in or attached to a hole comes off, in which case the cleaning can be achieved faster than previously, and when using a cleaning liquid or steam, and with a flow rate as low as possible, in which case after the cleaning a minimum amount of liquid, such as water, or no liquid at all, is left on the suction roll or below it. When superheated steam is used it is preferable to mix some water in it, in order to lower the temperature, to make the cleaning more efficient, and to create fast water drops in the jet which hit the holes.

The invention is described in more detail below with reference to the enclosed drawings, in which figure 1 shows a partly cut perspective view of a preferred embodiment of the invention at one end of a grooved suction roll to be cleaned; figure 2 shows from one side the distribution box and a part of the grooved suction roll according to the embodiment in figure 1 , and figure 3 shows a cross-section of one end of the device according to figure 1.

The distribution box of a cleaning device according to the invention is marked with the reference number 1 in the drawings. As seen in figure 1 the distribution box 1 is connected via a flexible hose 7 to a reservoir 6 of pressurised cleaning medium, such as water, steam or air. In figure 1 the distribution box 1 is in its initial position, i.e. at one end of the grooved suction roll 9 to be cleaned, and the distribution box 1 is positioned in its longitudinal direction in parallel with the axis 15 of the grooved suction roll 9 and arranged to be moved, supported on the wheels 5, in this direction along an axial rail 4 arranged above the grooved suction roll 9. The moving means of the distribution box 1 are not shown, but they can be wires fastened to the distribution box 1, and by pulling the wires the distribution box 1 can be made to move along the rail 4 when supported on the wheels 5. Further a roller 8, which can be lowered and which fits into the grooves of the grooved suction roll 9 is arranged in the distribution box, whereby the object of the roller 8 is to align the distribution box 1 during the washing operation.

The distribution box 1 is shown in more detail in figures 2 and 3. As seen in figure 2, there is a nozzle row 2 at the lower surface of the distribution box in the longitudinal direction of the distribution box 1, the row containing a plurality of needle nozzles 3 at a distance from each other. The needle nozzles 3 are located at such a distance from each other that they direct a jet of the washing medium into the grooves 10 of the grooved suction roll when the roller 8 of the distribution box 1 is lowered into a groove 10 of the grooved suction roll 9.

Selected grooves 10 of the grooved suction roll 9 have holes 11 at a peripheral distance from each other, the holes being in conjunction with a possible suction box (not shown) located within the grooved suction roll 9. In this case the distribution box 1 is at a point on the surface of the grooved suction roll 9, where the felt or wire is not in contact with the grooved suction roll. Alternatively, the suction can be created in the holes 11 of the grooved suction roll 9 by connecting the hollow axis 15 of the grooved suction roll 9 to a negative pressure source.

The hole size of the needle nozzles 3 is very small, at most about 4 mm and advantageously about 1 to 3 mm, for instance 2 mm. Due to their small hole size, the needle nozzles 3 direct a very sharply defined jet of washing medium against the grooved suction roll 9.

Figure 3 shows more specifically how the distribution box 1 is arranged on a profile rail 4 fastened to the frame 14 of the grooved suction roll 9. The tube-like distribution box 1 is fastened by a bolted joint 13 at the lower end of a bracket 12, and at the upper end of the bracket 12 there are wheels 5, which are pivoted so that they can rotate around an axis, which is transverse to the longitudinal direction of the distribution box 1, in order to be able to move the distribution box 1 in its longitudinal direction parallel to the axis of the grooved suction roll. The spraying direction of the needle nozzles 3 can be adjusted, so that they correspond exactly to the direction of the holes in the grooved suction roll, i.e. so that they are directed along the radius of the grooved suction roll, by loosening the bolted joint 13 and by rotating the distribution box 1 about its longitudinal axis, and then the bolted joint 13 is tightened again.

At the beginning of the cleaning operation the distribution box 1 is in the position shown in figure 1 at one end of the rail 4 and the grooved suction roll 9, when the aligning roller 8 of the distribution box 1 is in a groove of the grooved suction roll 9. At this time each needle nozzle 3 in the nozzle row 2 is located at a groove of the grooved suction roll 9. Cleaning medium is supplied at a high pressure from the cleaning medium reservoir 6 via the hose 7 to the distribution box 1 , from where the cleaning medium is sprayed from the needle nozzles 3 into the grooves of the grooved suction roll 9 (figures 2 and 3). In the cleaning medium reservoir 6 such a high pressure is maintained that when the cleaning medium is steam, the pressure of the steam is at least about 5 bar at the needle nozzles 3. The steam is preferably saturated steam containing water drops, which hit the grooves 10 and their holes 11 in the grooved suction roll 9 at a high velocity. If the cleaning medium is a liquid, such as water, it is sprayed at a pressure of at least about 100 bar from the needle nozzles 3, and when air is used this pressure is at least about 4 bar. Particularly when accumulated dirt is removed advantageously steam or water is used, but from time to time, air can be used to remove accumulated dust and lint, which is more easily detached, from the grooves 10. During the cleaning the grooved suction roll 9 is rotated about its axis 15, either continuously, one revolution or more revolutions, or periodically, in which case cleaning medium is sprayed onto the grooved suction roll 9, advantageously when the needle nozzles 3 are located over the positions of the holes in the grooves 10.

When the grooved suction roll 9, having the length of the distribution box 1 has been cleaned, the aligning roller 8 of the distribution box 1 is lifted from its groove 10 and the distribution box 1 is moved a distance corresponding to its length in the direction of the rail 4 for the next cleaning period supported on the wheels 5.

It is obvious that the cleaning device according to the invention can be arranged within the suction roll, however, structurally and regarding the maintenance, it is more advantageous to arrange the cleaning device outside the suction roll. Likewise, it is obvious that there may be a number of successive distribution boxes, as seen in the direction of the suction roll's rotation, in which case the distribution boxes advantageously can be moved independently of each other in the direction of the axis of the suction roll. Alternatively several nozzle rows may be arranged parallel in the same distribution box, i.e. so that the rows are located after each other in the rotation direction of the suction roll, in which case the needle nozzles in one nozzle row can be displaced to the side compared to the needle nozzles in the adjacent needle rows.

The needle nozzles in the distribution box can also be closed and opened independently of each other, in order to spray cleaning liquid or steam only from those respective needle nozzles, which are situated at a hole in the suction roll.

The invention may be varied also in other ways within the scope of the enclosed claims.

Claims

1. A device for cleaning a suction roll, the device comprising:

- a distribution box (1), - at least one nozzle row (2) connected to the distribution box and arranged substantially parallel to the direction of the axis (15) of the suction roll (9) to be cleaned,

- means (4, 5) for moving the distribution box (1) over the surface of the suction roll (9) to be cleaned, and - means (6, 7) for supplying a cleaning medium at a pressure into the distribution box (1), characterised by a means (8) for aligning the nozzles (3) with the holes (11) of the suction roll (9) to be cleaned, and by that the nozzles are needle nozzles (3).

2 A device according to claim 1, characterised in that the hole size of the needle nozzles (3) is at most about 4 mm, advantageously about 1 to 3 mm.

3. A device according to claim 1 or 2, characterised by means (4, 5) for moving it over the outer surface of the suction roll (9) to be cleaned.

4. A device according to any previous claim, characterised in that the needle nozzles (3) in an axial needle nozzle row (2) are located at a distance from each other which is defined by the distance of the holes (11) in the suction roll (9) to be cleaned.

5. A device according to any previous claim, characterised in that the distribution box (1) can be turned about its longitudinal axis, so that the needle nozzles (3) are directed in the radial direction of the suction roll (9) to be cleaned.

6. A device according to any previous claim for cleaning a grooved suction roll (9), characterised in that in order to align the needle nozzles (3) with the holes (11) of the grooved suction roll (9) to be cleaned, a roller (8) or the like is fastened to the distribution box (1) and pivoted on an axis in parallel to the axis (15) of the suction roll, the peripheral part of the roller fitting into the grooves (10) of the grooved suction roll (9) to be cleaned.

7. A device according to claim 6, characterised in that the needle nozzles (3) in the axial needle nozzle row (2) are located at a distance from each other which is defined by the grooves (10) in the grooved suction roll (9) to be cleaned.

8. A device according to any previous claim, characterised in that the means for supplying cleaning medium at a pressure into the distribution box (1) comprises a source (6) of steam, liquid and/or air.

9. A device according to claim 8, characterised in that the steam source

(6) is arranged to generate in the needle nozzles (3) a pressure of at least about 3 bar, advantageously 4 to 6 bar.

10. A device according to claim 8, characterised in that the liquid source (6) is arranged to generate in the needle nozzles (3) a pressure of at least about 100 bar, advantageously 100 to 150 bar.

11. A device according to claim 8, characterised in that the air source (6) is arranged to generate in the needle nozzles (3) a pressure of at least about 4 bar, advantageously over 6 bar.

12. A device according to any previous claim, characterised in that the means (4, 5) for moving the distribution box (1) over the surface of the suction roll (9) to be cleaned is arranged to move the distribution box (1) substantially parallel with the nozzle row (2).

13. A device according to any previous claim, characterised in that the means (4, 5) for moving the distribution box (1) over the surface of the suction roll (9) to be cleaned is arranged to move the distribution box (1) mainly in parallel with the axis (15) of the suction roll (9) to be cleaned.

14. A device according to claim 13, characterised in that the means for moving the distribution box (1) over the surface of the suction roll (9) to be cleaned comprises a rail (4) which is parallel to the axis (15) of the roll, and wheels (5) pivoted in the distribution box, this way the distribution box (1) can be supported on the wheels and moved along the rail (4).

15. A device according to any previous claim, characterised in that there are a plurality of successive nozzle rows (2) in the distribution box (1).