EP1842960A1 - Method and device for cleaning the surface of a moving belt - Google Patents

Abstract

Method for cleaning the surface (16) of a moving web of paper comprises spraying it with cleaning fluid under pressure. The mixture of air, soiling and fluid produced is passed through a collector (4) where the soiling is deposited. The collector is cyclically cleaned. An independent claim is included for apparatus for carrying out the method which incorporates a spray (2) and a collector cleaning unit.

Description

State of the art

The invention relates to a method for cleaning a surface, wherein the surface is acted upon by a jet of pressurized cleaning fluid, thereby removing contaminants adhering to the surface and a surface-directed stream of a mixture of ambient air, the cleaning fluid and the surface detached particulate contamination is generated. Furthermore, the invention relates to a device for cleaning a surface, with which the aforementioned method is feasible.

Such methods and associated apparatus are well known and are described e.g. used in papermaking, where the surfaces of the moving belts are to be cleaned in the form of paper machine clothing endlessly circulating on rollers or cylinders. Thus, there is a need for cleaning e.g. in the area of the dryer sections of paper machines, in which the paper web already pre-dewatered in the so-called press section are guided on a so-called drying wire and steam-heated cylinder, whereby the moisture content of the paper web is reduced to an extent which ultimately allows the paper to be wound up.

In papermaking, the so-called dryer fabric used in the dryer section is subject to constant contamination, in particular by adhesives, bitumen, waxes, resins and / or printing ink. Pollution often takes the form of agglomerated particles that develop different sizes depending on the length of time they have accumulated. Since the contaminants would detach on reaching a certain size of the fabric and then affect its quality as a result of adherence to the paper, a regular cleaning of the surface of the fabric is required.

This surface cleaning is typically carried out with a so-called Traversierreiniger which is transversely to the direction of movement of the tape, ie the papermachine clothing, movable, and always acted on at any time only a portion of the tape. The Traversierreiniger is located at a point in the course of the endless belt, where it is separated from the paper web, so that the tape is present separately. The Traversierreiniger typically has at least one nozzle head, which is equipped with high-pressure water nozzles.

This nozzle head is moved by means of a traversing computer-controlled transversely to the clothing running direction. Typical belt speeds are between 800 m / min to 2000 m / min. When hitting the water jets on the fabric contaminants are replaced and entrained by the air flow, which is carried along by the fabric, and thus distributed untargeted throughout the machine and stored later, for example, on the machine housing or covers, but also at the Covering yourself, so that a certain part of the pollution is always recycled.

From the DE 195 07 938 A1 a device for cleaning a conveyor belt of a papermaking machine is known, in which a cooperating with the nozzle suction chamber is present. The suction chamber is formed by a suction cup, which surrounds the nozzle jacket-shaped. By assigning the suction cup to the rotatably formed nozzle, the dirt and / or water mist or residual water detached from the conveyor belt by means of the jet is to be drawn into the suction space and removed. The cleaning medium should be under a pressure of 100 bar to 1000 bar and the nozzle have a rotational frequency of 2000 to 3000 revolutions per minute.

A disadvantage of this known device, it is to be considered that the volumes of dirt and / or water mist or residual water arising during cleaning including the contaminants therein are very large, so that on the one hand the suction bell must be very large and the other required for suction Suction pumps must be sized accordingly large. In addition, there is a risk that the detached contaminants within the suction cup and the leading away from there lines for extracting the mist reflected and thus constrict the cross sections in the long term and thereby reduce the efficiency and increase the power consumption of the suction pump. In addition, the rapidly rotatable nozzle according to the DE 195 07 938 A1 considered to be detrimental to traversable nozzle tubes with rigidly attached nozzles.

task

The invention has for its object to provide a method and apparatus for cleaning a surface of a moving belt, with which or with the largest possible portion of the contaminants removed from the tape can be permanently removed from the tape, at the same time the apparative Effort and energy consumption should be kept as low as possible. Also, a trouble-free continuous operation without maintenance-related downtime should be possible.

solution

Starting from the method of the type described above, the object is achieved in that the flow of the mixture of ambient air, the cleaning fluid and the detached from the surface particulate contaminants is passed through a collector and / or along a collector along the collector surfaces at least accumulate the contaminants and accumulate during a period of time, the pollutants are cyclically cleaned from the collector surfaces.

The basic principle of the solution according to the invention thus consists in the provision of collector surfaces, which are flowed by the flow of the aforementioned mixture and then flow around it, wherein the current of the mixture sufficiently large collector surfaces must be offered in order to achieve a sufficiently high deposition rate of the entrained dirt particles. The invention is thus based on the principle of separating from the stream of the mixture a certain component, namely the contaminants, whereas the other components, which are much larger in volume, can pass through the collector without harmful effects, because water, which is the most common cleaning fluid, and Ambient air have no negative effects within the paper machine, as they are already present in large quantities anyway. Thus, while ideally only the contaminants are brought to the collector surfaces for attachment, in practice, if the cleaning fluid is aqueous, always a mixture of water and dirt particles attach to the collector. Since the temperatures within eg a paper machine, in particular in the area of the dryer section, are comparatively high (approximately between 70 ° C. and 150 ° C.) and the air velocity is very high, the cleaning fluid which initially forms together with the dirt particles on the collector surfaces accumulates, after a relatively short time volatilize again in the ambient air of the band and thus not further negative in appearance.

While thus in the prior art according to the DE 195 39 015 A1 the entire stream of the mixture is sucked, including the entire ambient air, the mass or medium to be treated according to the invention is significantly reduced by the separation taking place on the component in the stream of the mixture, which is the only undesirable, namely the surface detached contaminants. For this reason, the method according to the invention can be carried out with particularly good energy efficiency and also with comparatively low construction costs.

In a preferred embodiment, the surface of a moving belt is applied to the fluid for cleaning purposes. The band movement causes a following air flow, which makes the extraction of the entire stream of the mixture more difficult, but facilitates a targeted collector inflow. The same is true even with a reverse relative movement between the impingement stream and the surface to be cleaned, i. when the surface is stationary, but the loading current is moved.

Preferably, the application of the surface is interrupted during the cleaning of the collector. Thus, the processes of attaching the dirt particles during the cleaning operation are clearly separate from the process step of cleaning the collector in order to provide sufficient for this sieve for a next accumulation cycle again sufficient storage capacity. According to one embodiment of the invention, the application of the tape is carried out continuously at changing locations of the band, since even with wide bands can be used with relatively small loading devices. In this case, the loading device is moved transversely to a strip running direction during the application of the tape.

In order to avoid a renewed contamination of the surface with the cleaned dirt particles when cleaning the collector, it is proposed to make the cleaning of the collector laterally next to the surface or above the surface. Important here is a sufficient distance, which makes it possible to safely keep the resulting during the cleaning process of the collector stream from the previously cleaned surface.

The invention further ausgestaltend is provided that the cleaning fluid under a pressure of 10 bar to 400 bar, preferably 30 bar to 300 bar from at least one nozzle escaping water. Also, in the cleaning of the collector with a Abreinigungsfluid should preferably be used with pressurized water.

In order to avoid that water drips from the latter during the process of accumulation of particles on the collector surfaces and thus returns to the surface, the collector surfaces can be heated during the application of the surface, since this shortens the residence time of the water at the collector surfaces and the Formation of drops is avoided.

In terms of device technology, the above-mentioned object is achieved by a device for cleaning a surface, wherein the device has a loading device, with which the surface can be acted upon by at least one jet of pressurized cleaning fluid, wherein contaminants adhering to the surface by the application removable and a surface directed away stream of a mixture of ambient air, the cleaning fluid and the detached from the surface particulate contaminants can be generated, and which is characterized by a collector, through and / or along which the current of the mixture feasible is and has the collector surfaces on which at least the contaminants can be accumulated and accumulated during a period of time, and which is further characterized by a cleaning device with which the dirt from the collector surfaces abreinigba r are.

With the device described above, the method according to the invention can be carried out particularly easily and efficiently. Particularly advantageous is the application of the device according to the invention in a (fast) moving belt whose surface is to be cleaned.

Preferably, the loading device is movable transversely to the movement device of the belt and with her only a portion of the width of the belt acted upon simultaneously. Even with very wide bands, the size of the loading device can be kept small in this way.

Furthermore, it is provided according to the invention that the cleaning device is arranged in a laterally adjacent to the surface or above the surface cleaning station. There, ie typically outside of the cleaning area, the stream of cleaning fluid and cleaned dirt particles is stored or removed during or after cleaning.

In the vicinity of the impact area of the cleaning fluid on the surface, i. in the vicinity of the area where the mixed flow is produced to be able to provide sufficiently large collector surfaces, it is proposed that the collector has surface elements arranged parallel to one another and spaced parallel to the direction of movement of the belt, on which the collector surfaces are located. By a lamellar structure of the surface elements or the contact surfaces can be realized in a small space, an effective collector surface, wherein the flow resistance of a lamella package thus formed is low, so that a flow through the same is achieved, whereby all surface elements, i. Collector surfaces are flowed around.

Furthermore, it has been found to be particularly advantageous that the surface elements of sheets that can be provided with openings, or formed by screens or grids or nets. It has been shown that flow edges, in particular, due to the associated turbulence, in particular the formation of dead water areas located behind, favor the deposition of the dirt particles.

Finally, it is proposed that the surface elements be horizontally, i. parallel to the surface of the belt to be cleaned, or vertically, in particular parallel to the direction of tape travel, since in this case the best collection rates of dirt particles could be achieved.

embodiment

The invention will be explained in more detail with reference to an embodiment of a cleaning device, which is shown in the drawing.

Figur 1

eine Draufsicht auf eine erfindungsgemäße Reinigungsvorrichtung,

Figur 2

eine Seitenansicht eines Kollektors und

Figur 3

eine Draufsicht auf den Kollektor gemäß Figur 2.

It shows:

FIG. 1

a top view of a cleaning device according to the invention,

FIG. 2

a side view of a collector and

FIG. 3

a top view of the collector of Figure 2.

An apparatus 1 for cleaning a surface 16 of a moving belt comprises a loading device 2, with which the surface 16 of the belt can be acted upon by a plurality of jets under a pressure of 100 bar standing water. The jets of water emerge from nozzles, not visible in FIG. 1, on the underside of a nozzle head 3, which are connected via lines not shown in detail below Pressure-connected water supply system is connected. The loading device 2 is connected to an overlying collector 4, which consists of a plurality of parallel, spaced apart collector plates. The construction of a collector 4 is described in more detail in FIGS. 2 and 3. The structural unit formed from loading device 2 and collector 4 is attached via a holder arm 6 to a carriage 7. The carriage 7 is traversable along a cross member 8 in a known manner transversely to the direction of movement 9 of the band. The tape runs parallel to the sheet planes of the drawing and is completely bridged by the cross member 8, wherein the cross member 8 is supported by two laterally arranged next to the band vertical bars 10. The tape is the endless circulating dryer of a paper machine and has a width of 10 m.

FIG. 2 shows that a collector 4 is formed from a plurality of collector plates 5, which are arranged vertically one above the other and have a spacing from one another and are each oriented horizontally. The collector plates 5 form at their two opposite surfaces in each case the collector surfaces of the collector 4. Furthermore, they form a lamella packet which is held firmly in its geometric shape by means of five threaded rods 11 and spacers 12 placed between each two adjacent collector plates 5. On a vertically extending and connected at its bottom with the nozzle head 3 holding tube 13 of the holding arm 6 shown in Figure 1 is connected, which in turn represents a connection with the traversing device. In the present case, seven nozzles 14 are arranged on the nozzle head 3, the jet direction of which is illustrated by the lines 15 impinging on the band 16 at an angle α of approximately 45 °. The impingement line 21 of the jet streams coincides with the projection of the leading edge of the collector plate 5 into the surface 16 of the belt.

In the cleaning operation, the high pressure on the surfaces 16 of the belt incident water does not atomize at a reflection angle of 45 ° to the belt surface of this, but due to the high belt speed, there is a high velocity of the ambient air in the direction of arrow 17, so that the horizontal Movement component of the atomized, reflected from the strip surface water and the detached dirt particles or a mixture of the above two components in a relatively close distance above the strip surface is reversed. Thus, the atomized water flows, including the detached dirt particles in sheets, approximately through the arrows 18 to be clarified, on the front of the collector 4 to. There, the current through the leading edges 19 of the collector plate 5 is divided into a number of intermediate spaces 20 between two adjacent collector plates 5 corresponding number of part streams. The leading edges 19 of the collector plate 5 cause certain turbulences and subsequent dead water areas, which offer preferred deposition conditions for the dirt particles. In the front region of the collector 4, seen from the inflow side, therefore, the largest deposition rate will occur.

Through experiments it could be confirmed that with the help of the illustrated collector 4, the majority of the detached dirt particles actually accumulates on the collector plate 5 and can be removed by means of cyclic cleaning of the collector 4 from the paper machine. After a certain period of time, which in practice take different lengths and e.g. between 0.5 hours and 2.0 hours (corresponding to about 5 to 10 overflows of the cleaning device), the loading capacity of the collector 5 is exhausted, so that it must be cleaned. For this purpose, the assembly consisting of loading device 2 and collector 4 moves into a position laterally next to the belt 9, where a cleaning station 22 is fastened to the frame of the crossbeam 8. The cleaning station has a housing 23, the entry and exit region of which can be opened and closed by means of a pivotally mounted door 24, which is actuated by means of a pneumatic cylinder 25. Shortly before the retraction of the collector 4 together with loading device 2 in the cleaning station 22, the door 24 is opened and then closed again. The unit consisting of collector 4 and cleaning device 2 is then located in the cleaning position clarified by dashed lines A in FIG. The cleaning within the closed to the ambient air housing 23 of Abreinigungsstation 22 by means of an application of the collector surfaces, i. the accumulated dirt particles thereon, with pressurized water, which likewise emerges from a plurality of nozzles, which are not shown in detail in Figure 1. The only a few minutes cleaning cycle frees the collector surfaces of all agglomerated there dirt particles, so that when leaving the Abreinigungsstation 22 again the full loading capacity of the collector 4 is available, so that the cleaning process of the tape can be continued.

The resulting from cleaning the collector 4 suspension of dirt particles and water can either be removed immediately from the cleaning station or in one sediment the lower reservoir, whereupon the accumulating above water can be deducted or used for a new cleaning process. In such a procedure, a removal of the sediment from the sump of the cleaning station 22 is required at certain intervals.

Claims (17)

A method of cleaning a surface (16), wherein the surface is exposed to at least one jet of pressurized cleaning fluid, thereby removing contaminants adhering to the surface (16) and a flow of a mixture of ambient air, the water, away from the surface (16) Cleaning fluid and the detached from the surface (16) particulate contaminants is generated, characterized in that the flow of the mixture is passed through a collector (4) and / or on a collector (4), at the collector surfaces, at least the contaminants accumulate and accumulate during a period of time, whereby the contaminants are cyclically cleaned by the collector surfaces. A method according to claim 1, characterized in that the surface to be cleaned (16) is that of a moving belt. A method according to claim 1, characterized in that the application of the surface (16) during the cleaning of the collector (4) is interrupted. Method according to one of claims 1 to 3, characterized in that the loading of the surface (16) takes place continuously at changing locations of the surface (16). Method according to one of claims 2 to 4, characterized in that a loading device is moved during the application of the tape transversely to a strip running direction. Method according to one of claims 1 to 5, characterized in that the loading device (2) is moved together with the collector (4). Method according to one of claims 1 to 6, characterized in that the cleaning of the collector (4) takes place laterally next to the surface (16) or above the surface (16). Method according to one of claims 1 to 7, characterized in that the cleaning fluid under a pressure of 10 bar to 400 bar, preferably 30 bar to 300 bar from at least one nozzle (14) leaking water. Method according to one of claims 1 to 8, characterized in that the cleaning of the collector (4) with a Abreinigungsfluid, preferably with pressurized water, takes place. Method according to one of claims 1 to 9, characterized in that the collector surfaces are heated during the application of the surface (16). Device (1) for cleaning a surface (16), with an impingement device (2), with which the surface can be acted upon by at least one jet of pressurized cleaning fluid, wherein contaminants adhering to the surface (16) can be removed and a from the surface (16) can be generated directed away stream of a mixture of ambient air, the cleaning fluid and that of the tape (16) detached contaminants, characterized by a collector (4), through which and / or along which the stream of the mixture is feasible and has the collector surfaces on which at least the contaminants can be accumulated and accumulated during a period of time, and characterized by a cleaning device with which the contaminants from the collector surfaces can be cleaned. Apparatus according to claim 11, characterized in that the loading device, the surface (16) of a moving belt is acted upon. Apparatus according to claim 11 or 12, characterized in that the loading device (2) transversely to the strip running direction (9) is movable and with her only a portion of the width of the tape can be acted upon simultaneously. Device according to one of claims 12 or 13, characterized in that the cleaning device is arranged in a laterally adjacent to or above the belt cleaning station (22). Device according to one of claims 12 to 14, characterized in that the collector (4) parallel to each other, spaced from each other and parallel to the strip running direction (9) aligned surface elements, on which the collector surfaces are located. Apparatus according to claim 15, characterized in that the surface elements of sheets, which may be provided with apertures, or of screens or nets or grids are formed. Apparatus according to claim 15 or 16, characterized in that the surface elements are aligned horizontally or vertically.

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