EP1760191B1 - Device and method for cleaning conveyors and fabrics, in particular of paper machines - Google Patents

Abstract

The device has a cleaning medium container (1), water, compressed air (3), valves, pipelines, cleaning central unit, pump, check valves, mixing points and pressure reducing unit to provide foam (16). The foam is applied on a circulating conveyor belt by a spray rod (14) through a set of openings (15). The spray rod has boreholes, and the sum of the cross sectional surfaces of the boreholes is smaller or equal to the cross sectional surface of the spray rod. Independent claims are also included for the following: (1) a method for cleaning a circulating conveyor belt of a paper machine (2) a method for retrofitting a cleaning system for cleaning a circulating conveyor belt of a paper machine.

Description

TECHNICAL AREA

The present invention relates to a device for cleaning circulating conveyor belts of a paper machine, in particular for cleaning in interrupted production. Furthermore, it relates to a method for cleaning circulating conveyor belts and a method for retrofitting an existing cleaning system for circulating conveyor belts.

STATE OF THE ART

In a paper machine, a plurality of conveyor belts is arranged. These can take over pure transport function, but they can also, as for example in a Fourdrinier, for the actual sheet formation or for specific drying operations or press resp. Be responsible for drainage processes. Since these conveyor belts are either exposed directly to the pulp or at least fresh and thus deposits causing paper, it can not be avoided that fibers, binders, pigments, etc., but possibly also components of coatings, etc. during operation on and in such conveyor belts deposit and their function, such as their water permeability and homogeneous surface, adversely affect.

The periodic or continuous cleaning of conveyor belts of a paper machine, that is, for example, the felt, the dryer fabric belt or the wet screen belt, but equally a round screen, so is required to to be able to maintain a smooth operation of the paper machine. If the periodically performed cleanings are omitted, this leads to irregular paper, paper webs to be torn, banding, insufficient drying, etc.

The cleaning can be done either during production, and here both continuously and in sections. Likewise, the cleaning can be carried out at a stationary paper machine, and thereby either at standstill of the conveyor belt or moving conveyor belt, the latter typically in crawl (so-called crawl speed cleaning, that is compared to the production greatly reduced speed) done.

When the paper machine is stationary, but also during operation, for example, cleaning using cleaning solutions which are sprayed on has proved to be useful. For this purpose, specific devices, such as those in the EP-A-0 731 212 are described, find application. In this case, a liquid detergent is sprayed with a nozzle on the running fabric tape and collected the resulting soil solution with a catcher.

With a stationary paper machine and necessary deeper cleaning, the application of foam has proved to be useful because when using foam by its stabilizing effect as long as possible residence time of the detergent on and in the tissue, ie where the actual cleaning is to take place can be effected , In this case, the procedure is that the staff equipped with appropriate foam pumps or foam cars apply the crawl moving conveyor belt with foam manually. The required protective clothing is very complex and uncomfortable, and also the manual application is usually very time consuming and not very reliable and inhomogeneous.

From the DE 2231141 such a device for producing foam is disclosed, and this for the purpose of cleaning tapes of a paper machine. In this document it is noted that the foam is applied with a hose is, which has a mouthpiece at the end.

Also the cleaning of tapes of a paper machine not with foam but with a liquid is possible. From the US 6468397 For this purpose, for example, a device is disclosed in which a liquid is actively sprayed onto the belt, but this from below, which is possible only with a liquid and gives an additional positive mechanical effect of the application of the liquid.

PRESENTATION OF THE INVENTION

The invention is therefore an object of the above problems of the prior art overcome. It is therefore intended to propose an alternative device for cleaning circulating conveyor belts of a paper machine, in particular for use with a stationary paper machine and for cleaning conveyor belts in crawlspace.

The solution to this problem is achieved by providing means for providing foam. The foam provided thereby is transported to at least one spray bar, for example via lines, and is applied by means of at least one spray bar to the conveyor belt through a plurality of openings.

The spray bar is preferably above, e.g. arranged transversely to the direction of the tape, so that the foam from the openings can fall freely on the conveyor belt.

The essence of the invention thus consists in the fact that it is surprisingly possible to transport foam provided in a separate unit to a spray bar and to apply it through corresponding openings in this spray bar, without the foam decomposing during this transport and thereby substantial proportions of non-foamed Cleaning agents are applied. It can thus be produced as efficiently as possible in the separate unit of the foam, and applied uniformly over the width of the conveyor belt. Normally the conveyor belt is a fabric or a felt based on plastics such as PU, PA, Polyester, possibly also on a metallic basis.

According to a first preferred embodiment of the invention, the openings are holes or simple holes in the spray bar. Typically, there are at least 3 such openings per meter in operation, preferably 5 to 10 such openings or 7 to 20 such openings per meter are arranged along the spray bar. It can be seen that the foam can be applied simply and efficiently over the entire transport path, ie from the means for providing foam to the conveyor belt, by dimensioning the structure such that the sum of the cross-sectional areas of all the holes of a spray bar is smaller ( or at most equal to) the cross-sectional area of the spray bar (ie, the line cross-section of the spray bar). If the flow cross-sections are adjusted in this way, pressure changes do not occur at any point, which cause the foam to disintegrate and the cleaning agent to be returned to the undesired liquid state.

In the context of conventional cleaning agents at conventional concentration, it is found that the bores advantageously each have a cross-sectional area in the range of 7-100 mm ² , preferably in the range of 10-150 mm ² , typically 20-30 mm ² . The holes or better openings may in principle have different cross-sectional areas, such as triangular, square, rectangular, hexagonal, elliptical, etc., but the structure is particularly simple if the holes each have a circular opening. It turns out that then preferably the inner diameter in the range of 3-10 mm, preferably in the range of 4-7 mm is selected.

On the other side of the spray bar can be designed such that it has a cross-sectional area in the range of 500- 4000 mm ^2, preferably in the range of 1000-3500 mm ^2. Again, the spray bar may have different cross-sections, in turn, for example, triangular, square, rectangular, hexagonal, elliptical, etc., is particularly easy to use a cylindrical tube. When using a tubular spray bar, it may have a substantially circular internal cross-sectional area with a diameter in the range of 25-110 mm, preferably in the range of 40-80 mm.

The bores are preferably arranged on the spray bar so that the foam emerging from the bores falls by gravity onto the conveyor belt. In order to prevent this in turn, that the foam decomposes, it proves to be advantageous to arrange the holes substantially on a row or alternately offset on the conveyor belt facing the underside of the spray bar. The holes can distribute the foam on the conveyor belt evenly and in a manner sufficient for cleaning if, as is preferred, they each have a spacing of 50-200 mm, particularly preferably a spacing of 50-150 mm. It is also possible to provide means by which the spray bar is moved in crawl running conveyor belt in the plane parallel to the surface of the conveyor belt perpendicular to the conveying direction of the conveyor belt back and forth to effect an optimal application with foam.

Normally, the at least one spray bar is arranged essentially perpendicular to the running direction of the conveyor belt and parallel to its surface, preferably at a distance of 50-500 mm, in particular 150-250 mm, from the surface of the conveyor belt.

According to a preferred embodiment of the device, the means for the continuous provision of foam are composed of means for supplying an aqueous solution of cleaning agent and at least one element for producing foam by targeted supply or admixture of gas, for example air.

The element may be a specific mixing chamber for producing foam. However, the element can also be designed simply as a T-piece, in which, for example, the compressed air is supplied via a leg to the linearly flowing cleaning agent.

Preferably, air is supplied in the form of compressed air, this under a pressure in the range of 2-6 bar via a conduit with a diameter in the range of 10-30mm.

In order to ensure a gentle transport between the generation of the foam and the spray bar, it proves to be advantageous to provide substantially curvilinear lines between the element and the spray bar. In particular, it is advantageous to arrange lines of a length of not more than 0.5-2 m between the element and the spray bar. These lines should have a diameter which is in the same range as that of the spray bar.

A further preferred embodiment of the device according to the invention is characterized in that cleaning agent is supplied from a detergent container to a cleaning central unit in which it is mixed in the desired ratio with supplied water, and subsequently this mixture, optionally via a valve and / or a check valve, the element is supplied. The cleaning agent is preferably formulations containing surfactants, solvents, acids, alkalis and / or enzymes, or mixtures of two or more of these components. The cleaners are presented as an aqueous solution with a content of 0.1-100% and then For example, in a ratio of 2: 1 (detergent solution to water) mixed with water. The use of Alphasolv ^® AP is possible, for example, as available from Kolb AG, Switzerland.

A further preferred embodiment is characterized in that in addition means for rinsing are arranged, in particular with water, which may also be the spray bar, which is controlled differently for this purpose, that is, which is temporarily exposed to rinse water. It is also possible to provide means for extracting detergent and / or water.

Furthermore, the present invention relates to a method for cleaning a circulating conveyor belt of a paper machine. The method is particularly characterized in that foam is provided and this is supplied to at least one spray bar. The foam is then applied to the conveyor belt by means of the spray bar through a plurality of openings, in particular, the sum of the cross-sectional areas of all holes of a spray bar is chosen smaller (or equal) of the cross-sectional area of the spray bar.

Preferably, a device as described above is used.

A preferred embodiment of the method is characterized in that the cleaning takes place during the standstill of the paper machine, wherein the conveyor belt is acted upon either at a standstill or continuously in crawlspace with foam. It is particularly preferably applied in the range of 0.1-6 1 / m ² cleaning mixture and more preferably the conveyor belt is moved at a speed of 10-100 m per minute.

Moreover, the present invention relates to the retrofitting or conversion of a paper machine to a device, as described above for carrying out a method, as also explained above. The method for retrofitting a cleaning system for cleaning a circulating conveyor belt of a paper machine is characterized in that an existing device in which a liquid can be applied via arranged on a spray bar nozzles in liquid form or in the form of a spray on a conveyor belt specifically is modified. This is accomplished by drilling at least some of the nozzles and / or replacing them with inserts having suitable openings, and optionally closing some of the nozzles, ensuring that the sum of the cross-sectional areas of all orifices of a spray bar is less than (or equal to) the cross-sectional area of the spray bar and, if not already present, providing means for, in particular, continuous provision of foam.

Further preferred embodiments of the invention are described in the dependent claims.

BRIEF EXPLANATION OF THE FIGURES

• Fig. 1 a) eine schematische Darstellung einer Reinigungseinheit für ein Transportband; und b)-d) Sprühstäbe von unten mit Blick auf die Einsätze mit Öffnungen in unterschiedlichen Bauweisen.

The invention will be explained in more detail with reference to embodiments in conjunction with the drawings. It shows:

• Fig. 1 a) a schematic representation of a cleaning unit for a conveyor belt; and b) -d) spray bars from below facing the inserts with openings in different construction methods.

WAYS FOR CARRYING OUT THE INVENTION

FIG. 1 shows a schematic representation of a device with which a conveyor belt 17 in a paper machine 19 (or a downstream unit) can be cleaned. In the present case, the conveyor belt 17 is the wet screen belt of a fourdrinier machine, but the cleaning device can equally be used for cleaning other conveyor belts in a paper machine and even for cleaning a round screen of a rotary screen machine. The conveyor belt 17 has, for example, a width of 5.7 meters and is moved during normal operation at a speed of, for example, 900 m per minute. It is, for example, a paper machine for the production of paper from recycled material.

The cleaning device has a cleaning central unit 7. This central unit is supplied from a detergent container 1 via a line 5 detergent. In the central unit 7, the cleaning agent is conveyed by a pump, and then mixed with water. In the present case, the water from a second container 2 and a line 6 is provided, it is also possible to directly connect a fresh water line. After mixing, a valve 9 is arranged, which serves to adjust the supplied dilute detergent solution. The central unit 7 can be set manually both with respect to the pump 8 and with respect to the valve 9, but preferably a control unit is provided which automatically controls this central unit, as well as the supply of compressed air described below.

Specifically, for example, about 3000 1 detergent per hour from the container 1 fed (for example, the product Alphasolv ^® -AP Kolb AG, Switzerland), and this mixed with about 1500 1 per hour of fresh water.

Downstream of the central unit 7, a check valve 10 is first arranged (this can also be arranged within the central unit 7), and then follows the actual mixing point 11, or the element in which the foam is generated.

At this mixing point 11 compressed air 3, which can be controlled manually or automatically via a valve 4, fed. It is concretely compressed air with a pressure of 4 bar, which is supplied in a pipe of about 1.25 cm diameter. Furthermore, a check valve 12 and a pressure reduction element 13 are arranged in the supply line for compressed air.

The element 11 is a simple T-piece, with the cross section of the pipe when feeding the compressed air is 1/2 inch and Alphasolv® cleaning agent is supplied. The flow and pressure conditions lead to the fact that in this element 11 the diluted cleaning agent is almost completely converted into foam.

The foam produced in the element 11 is then fed via the foam feed line 21, which has a cross-sectional area similar to that of the spray bar, a spray bar 14 which is arranged parallel above the surface of the conveyor belt 17 and perpendicular to the running direction (see arrow) of the conveyor belt , The length of the section 21 should have no curvature, and should have a length in the range of 0.5-2 m, so that the foam in this line section is not returned to the liquid phase.

The spray bar 14 has along its length on the bottom via inserts 15 with openings 18 through which the foam 16 emerges. Due to gravity, the foam falls in uniform distribution on the conveyor belt 17, which is typically moved forward in crawl, that is at a speed of about 70 m per minute. Approximately 4 1 cleaning agents per square meter of conveyor belt are applied in the form of foam.

The spray bar 14, as shown in the FIGS. 1 b) - d) is shown to be designed differently. In FIG. 1b ) the simplest construction is shown. In this case the spray bar 14 is a simple tube, for example with a circular cross-section, and with a diameter of 2 inches, that is 5.08 cm. Along the bottom edge 20, 50 holes are drilled in the pipe 14 at a hole-to-hole distance of 10 cm, each hole having a diameter of 5-6 mm.

So that the foam can be safely transported intact, the sum of all cross-sectional areas of the holes 18 should be smaller than the cross-sectional areas of the spray bar. In this particular case, there are 50 holes 18, each with a cross-sectional area of 0.3 cm ² , giving a total cross-sectional area of the holes of 15 cm ² . The spray bar 14, in turn, with a diameter of 2 inches has a cross-sectional area of 19 cm ² . Thus, this requirement is satisfied and the foam is not destroyed during transport.

Another construction is in Figure 1c ). This is a spray bar 14, which has at the lower edge 20 via recesses, in which inserts 15 are used. For example, they may be inserts which normally include nozzles for spraying cleaning fluid. These have been drilled out (or replaced by corresponding other inserts) in this embodiment, so that there are no longer any nozzles but rather larger openings 18 for the exiting foam 16. Thus, for example, an already existing cleaning system can be retrofitted by either drilling out or replacing the existing there nozzles for the application of cleaning liquid, and by additionally a unit for providing foam is grown.

Another embodiment is shown in FIG Figure 1d ). It may prove advantageous for a better distribution of the foam 16 on the conveyor belt 17, the openings either not exactly at the lower edge 20 but eg something against the direction of the conveyor belt (see arrow) to arrange, or, as in Figure 1d ) is shown, the openings each to be arranged alternately offset. For a better distribution effect of the openings, the spray bar can also be moved during the application, for example along its axis to cover a wider area or to equalize the distance between the openings.

• der Schaum kann problemlos in homogener Weise über die gesamte Breite des Transportbandes aufgetragen werden
• der Schaum kann automatisch, das heisst ohne Personal mit entsprechender Schutzbekleidung aufgetragen werden
• durch die erhöhte Effizienz und Homogenität der Auftragung kann der Zeitaufwand bei der Reinigung reduziert werden
• durch die gewährleistete Homogenität der Auftragung kann der Aufwand an Reinigungsmittel reduziert werden
• die Vorrichtung kann leicht an bestehende Infrastruktur angeschlossen werden
• die Vorrichtung kann leicht aus bestehenden Reinigungsanlagen abgeleitet werden (Umbau, Nachrüsten)

The proposed device or the proposed method is characterized, inter alia, by the following advantages:

• The foam can be easily applied in a homogeneous manner over the entire width of the conveyor belt
• the foam can be applied automatically, ie without personnel wearing appropriate protective clothing
• the increased efficiency and homogeneity of the application can reduce the time required for cleaning
• due to the guaranteed homogeneity of the application, the amount of cleaning agent can be reduced
• the device can be easily connected to existing infrastructure
• The device can be easily derived from existing cleaning systems (conversion, retrofitting)

LIST OF REFERENCE NUMBERS

1

Detergent container, detergent

2

water

3

compressed air

4

Valve

5

Lead from 1 to 7

6

Lead from 2 to 7

7

Cleaning CPU

8th

Pump, centrifugal pump

9

Valve

10

check valve

11

Mix point, tee

12

check valve

13

Element for pressure reduction

14

spray bar

15

Inserts with opening

16

foam

17

Conveyor belt, fabric tape, felt

18

opening

19

paper machine

20

Lower edge of 14

21

Foam supply line

Claims (16)

1. A device for cleaning revolving transport belts (17) of a paper manufacturing machine (19), comprising means (1-13) for the supply of foam (16),
   characterized in that
   the foam (16) is applied to the transport belt (17) by at least one spray rod (14) through a plurality of openings (15, 18).
2. A device according to claim 1, characterized in that the openings (15, 18) are boreholes (18) in the spray rod (14), wherein the sum of the cross-sectional areas of all boreholes of a spray rod (14) is smaller or equal to the cross-sectional area of the spray rod (14).
3. A device according to claim 2, characterized in that the sum of the cross-sectional areas of all boreholes (18) of a spray rod (14) is smaller that the cross-sectional area of the spray rod (14).
4. A device according to one of claims 2 or 3, characterized in that at least 3, preferably at least 5 to 20 boreholes (18) are provided per running meter of the spray rod (14), and that the boreholes (18) each have a cross-sectional area in the range of 7-100 mm², preferably in the range of 20-150 mm², or that the boreholes (18) have a circular opening with an inner diameter in the range of 3-10 mm, preferably in the range of 4-7 mm.
5. A device according to one of claims 2-4, characterized in that a spray rod (14) has a cross-sectional area in the range of 500-4000 mm², preferably in the range of 1000-3500 mm², or that a tubular spray rod (14) has an essentially circular inner cross-sectional area with a diameter in the range of 25-110 mm, preferably in the range of 40-80 mm.
6. A device according to one of claims 2-5, characterized in that the boreholes (18) are arranged essentially in one row or alternately staggered at the lower side of the spray rod (14) facing the transport belt (17), and that they preferably each are spaced at 50-200 mm, more preferably at 50-150 mm.
7. A device according to one of claims 2-6, characterized in that the at least one spray rod (14) is arranged above and essentially perpendicular to the running direction of the transport belt (17) and parallel to its surface, preferably spaced at 50-500, preferably 150-250 mm from the surface of the transport belt (17).
8. A device according to one of the preceding claims, characterized in that the means (1-13) for the continuous supply of foam (16) comprise means (1, 2, 5-10) for the delivery of a preferably aqueous solution of a cleaning agent (1) as well as at least one element (11) for the creation of foam by directed delivery of gas (3).
9. A device according to claim 8, characterized in that the gas (3) is delivered to the element (11), which preferably is a T-piece, in the form of pressurized air, more preferably at a pressure in the range of 2-6 bar.
10. A device according to one of claims 8-9, characterized in that between the element (11) and the spray rod (14) essentially curve-less pipes (21) of a length of not more than 0.5-2 m are arranged.
11. A device according to one of claims 8-10, characterized in that cleaning agent is delivered from a cleaning agent container (1) to a central cleaning unit (7), where it is mixed with supplied water (2) at the desired ratio, if applicable, and subsequently this mixture, or the cleaning agent, respectively, is delivered to the element (11) over a valve (9) and/or a check valve (10), if applicable.
12. A device according to one of the preceding claims, characterized in that additionally means for rinsing, preferably with water, are provided, which can also comprise the spray rod (14), which is differently actuated for this purpose, and/or that means for the suction cleaning of cleaning agent and/or water are provided.
13. A method for cleaning a revolving transport belt (17) of a paper manufacturing machine (19),
    characterized in that
    foam (16) is supplied and delivered to at least one spray rod (14), and that the foam (16) is applied to the transport belt (17) by the spray rod (14) through a plurality of openings (15, 18), wherein preferably the sum of the cross-sectional areas of all boreholes of a spray rod (14) is smaller or equal to the cross-sectional area of the spray rod (14).
14. A method according to claim 13, characterized in that a device according to one of claims 1-12 is used.
15. A method according to one of claims 13 or 14, characterized in that the cleaning takes place during the non-operation of the paper manufacturing machine, wherein the transport belt is supplied with foam (16) either during the non-operation or continually, and wherein preferably in the range of 0.1-61/m² of cleaning mixture are applied and more preferably the transport belt (17) is moved at a velocity of 10-100 m per minute.
16. A method for retrofitting a cleaning device for the cleaning of a revolving transport belt (17) of a paper manufacturing machine (19), in which a liquid can be applied to a transport belt (17) in liquid form or in the form of a atomized spray through jets arranged on a spray rod (14),
    characterized in that
    at least some of the jets are bored and/or replaced by insertions with openings (15), and, if applicable, some of the jets are closed, whereby it is ensured that the sum of the cross-sectional areas of all openings of a spray rod (14) is smaller or equal to the cross-sectional area of the spray rod (14), and that means (1-13) for the preferably continuous supply of foam (16) are provided.

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