WO2010103169A1

WO2010103169A1 - Conditioning equipment for the fabric of a fiber web machine

Info

Publication number: WO2010103169A1
Application number: PCT/FI2010/050132
Authority: WO
Inventors: John Fagerlund; Sami Makkonen
Original assignee: Metso Paper, Inc.
Priority date: 2009-03-09
Filing date: 2010-02-24
Publication date: 2010-09-16
Also published as: EP2406426A4; EP2406426A1; FI20095231A0; FI121386B; CN202766909U; FI20095231A

Abstract

The invention relates to conditioning equipment for the fabric of a fiber web machine. The conditioning equipment includes at least one cleaning head (10) adapted to be moveable back and forth in the transverse direction to the fabric (12) by means of guiding means (11). The cleaning head (10) has nozzle elements (13) arranged therein for supplying fluid to the fabric (12). The conditioning equipment additionally includes air flow means (14) for creating a suction effect in the cleaning head (10) as well as discharge means (15) connected to the cleaning head (10) for transferring the supplied fluid and the matter detached from the fabric (12) and collected by the suction effect away from the cleaning head (10). The discharge means (15) include a functional separator (16) for separating matter and fluid from air.

Description

CONDITIONING EQUIPMENT FOR THE FABRIC OF A FIBER WEB MACHINE

The invention relates to conditioning equipment for the fabric of a fiber web machine including - at least one cleaning head adapted to be moveable back and forth in the transverse direction to the fabric by means of guiding means,

- nozzle elements arranged in the cleaning head for supplying fluid to the fabric, - air flow means for providing a suction effect in the cleaning head, and

- discharge means connected to the cleaning head for transferring the supplied fluid and the matter detached from the fabric and collected by the suction effect away from the cleaning head.

During production, fibers and fillers attach to the fabrics of particularly the dryer sections of fiber web machines. These fibers and fillers disturb the production. Particularly in board machines, soiling of fabric edge sections has been observed, which produces edge rags in the wire intervals leading finally to web breaks. Other areas of the fabric also soil producing stickies and causing general decrease in the drying capacity. The problem still grows when the impurities accumu- lating in the fabric become sticky due to heating up and the web tends to attach to the fabric. In production lines using recycled raw material and particularly in board production lines, and more particularly with corrugated board grades, the above mentioned soiling of dryer section fabrics has become a major problem that increases break sensitivity.

To avoid problems related to soiling, fabrics are conditioned with various devices. Present devices are mainly online cleaners provided with a cleaning head that traverses in the cross direction to the fabric. That is, the fabric is continuously conditioned during the production handling a small area at a time. However, the conditioning capacity of known devices is insufficient for keeping the fabrics sufficiently clean. In known devices, matter detached from the fabric and fluid, such as the cleaning water, are led to a vacuum system via long pipe lines, which are expensive to build and use. In the equipment of the applicant, marketed under the product name OptiCleaner Dry, the suction effect is created in the cleaning head by an integrated ejector. In other words, long pipe lines are not needed. The flow provided with the ejector firstly creates a suction effect in the cleaning head and secondly removes the matter, collected by the suction effect, and the cleaning water from the cleaning head. The ejector makes the matter and fluid move fast and blows them out to the discharge means composed of an open tray. However, impurities consisting of the matter and fluid mist out from the saveall to the environment. That is, not only the fabric but also the equipment itself soils. In addition, a large channel extends over the entire width of the fiber web machine. In practice, it is difficult to find a sufficient installation space for a relatively large channel. Furthermore, the cleaning head must be installed against a roll. Also, the flow through the cleaning head is imperfect because the cleaning nozzles are located in the middle of the flow channel.

The object of the invention is to provide novel conditioning equipment for a fabric of a fiber web machine, the conditioning capacity of which is better than earlier but requires less energy than before. Thus fabrics maintain their operating condition longer than before as resoiling is non-existent. The characteristic features of the conditioning equipment according to this invention are that discharge means include a functional separator for separating matter and fluid from air. The separator can collect matter and fluid controllably without detrimental misting. Thus soiling of the conditioning equipment and its environment as well as that of the fabric are avoided. The use of a separator leads to other benefits as well, which are described in more detail in connection with the application examples. With suitable component selections, the conditioning equipment can be made compact and small, yet efficient. Using reliable conditioning equipment, fabrics of a fiber web machine maintain their appropriate operating condition. In this way known problems are avoided whereby it is possible to achieve a higher production rate than before for the fiber web machine. At the same time, web grades that have been problematic earlier can be included in the production.

The invention is described below in detail by making reference to the enclosed drawings which illustrate some of the embodiments of the invention, in which

Figure 1 is a side view of the equipment according to the invention, Figure 2a is a diagonal top view of the equipment according to

Figure 1,

Figure 2b is an enlargement of a part of Figure 2a, Figure 3 is a cross-sectional view of a part of the equipment according to the invention,

Figure 4 shows a basic diagram illustrating the operating principle of the equipment according to the invention.

Figures 1 and 2a show a part of a fiber web machine provided with conditioning equipment according to the invention. Fiber web machines include, for example, paper and board machines, which have several fabrics that require conditioning. Tissue machines and pulp drying machines are also fiber web machines. A lot of water is used for conditioning press felts and the water is removed together with the matter that causes soiling using felt suction boxes, for example. Instead, for the conditioning of dryer fabrics of dryer section, only a limited amount of water can be used and therefore high-pressure water showers are commonly used. Regardless of the operating princi- pie, the conditioning equipment is arranged in the vicinity of the fabric to be conditioned.

Figure 1 shows a side view of the conditioning equipment ac- cording to the invention. The conditioning equipment includes at least one cleaning head 10 adapted to be moveable back and forth in the transverse direction to the fabric 12 by means of guiding means 11. The surface area of the cleaning head is relatively small compared to the width of the fabric. Thus, for conditioning the entire fabric, the cleaning head is moved slowly back and forth while the fabric simultaneously moves fast in the transverse direction to the cleaning head. The cleaning head 10 has additionally nozzle elements 13 arranged therein for supplying fluid to the fabric 12. The fluid is usually fresh water which is sprayed at a high pressure toward the fabric. Using high pressure, even a small amount of water can provide a shower that efficiently conditions the fabric. Instead of or in addition to water, steam, for example, can be used as fluid.

Advantageously, the conditioning equipment also includes air flow means 14 for creating a suction effect in the cleaning head 10. In addition, discharge means 15 are connected to the cleaning head 10 for transferring the supplied fluid and the matter detached from the fabric 12 and collected by the suction effect away from the cleaning head 10. In this way, firstly even sticky matter can be detached from the fabric and secondly the fluid can be removed from the fabric surface together with the matter. This matter usually consists of fibers and fillers used in the web production. During the production, the cleaning head conditions the fabric continuously or periodically ensuring that the fabric maintains its operating condition and web attachment problems are avoided.

According to the invention, the discharge means 15 surprisingly include a functional separator 16 for separating matter and fluid from air. In practice, only air is mainly removed from the separator while the matter and fluid accumulate in the separator. In this way water-containing impurities misting around the cleaning head are avoided. Separators exist in various designs and their location can vary in different applications. Regardless of the application, the separator 16 includes an inlet connection 17 and an air exhaust connection 18. According to the invention, the cleaning head 10 is connected to the inlet connection 17 while the air flow means 14 are connected to the air exhaust connection 18. Thus the air flow means are located only after the separator, which means that mainly air only flows through the air flow means. It is also possible to refer to a kind of a suction box prior to which the matter conveyed with the air flow is mainly separated. Thus the air flow means can be composed of different components and the air flow means remain unsoiled both inside and outside.

According to the invention, the separator 16 is advantageously supported to guiding means 11. In this way the separator 16 is adapted to be moveable back and forth together with the cleaning head 10 in the transverse direction to the fabric 12. Then the flow connection 19 between the cleaning head 10 and the separator 16 is advantageously short and it can be provided with a virtually invariable structure. Advantageously, a con- trol possibility is arranged in the guiding means 11 and/or the flow connection 19, in which case the cleaning head 10 can be positioned relative to the fabric 12 in a way required by each installation position geometry. The separator can also be located fixedly, in which case only the cleaning head moves. Then the air flow from the separator to the cleaning head is led via a hose, and a vacuum is generated with a blower, for example .

During the continuous use of the conditioning equipment, matter and fluid continuously accumulate in the separator. Therefore, in addition to the inlet connection 17 and the air exhaust connection 18, the separator 16 includes a discharge connection 20, provided with closing means 21, for removing the separated matter and fluid. According to the invention, the closing means are advantageously so adapted that the operation of the separa- tor remains uninterrupted even during the discharge. Gravitational discharge is advantageously used together with closing means that operate according to the vacuum valve principle. Such closing means can be composed, for example, of two flexible membranes 22 adapted face to face, which separate due to the weight of the matter and fluid thus opening the discharge connection 20 (Figure 1) . Once the separator has emptied sufficiently, the membranes return against each other thus closing the discharge connection. Therefore the separator always contains some matter and fluid ensuring that an air flow through the discharge connection is prevented and the operation of the separator remains undisturbed. On the other hand, an actuator can be adapted in the closing means, whereby the separator can be emptied in a desired point, if required. To provide a controllable and tidy discharge, the discharge means 15 further include a collector 23 adapted underneath the discharge connection 20. From the collector, the matter and fluid are led to a sewer or to recycling, for example.

In a controlled discharge, a collecting pit 24, located at the edges of the fiber web machine, is advantageously used (Figure 2a) . Then the separator 16 is led above the collecting pit 24 and emptied. It is also possible to use a saveall tray connected to the separator, in which case the separator can be optimally dimensioned without increasing its volume in vain. Therefore, a saveall channel 25 extending across the fiber web machine is advantageously used as the collector 23 (Figure 1) . Then the separator can empty at any time and it is possible to use simple but automatic closing means, such as the above mentioned membrane closure. Along with the saveall channel, a collecting pit can be used as well. Then, for example, matter and fluid are led from the saveall channel to the collecting pit, which is used during the separator cleaning, for example. During cleaning, the separator is above the collecting pit. Moreover, the collecting pit is so large that the separator can be flushed even externally and the water flows to the collect- ing pit. Advantageously, the collecting pit is provided with a suitable gradient for removing the matter gravitationally . If necessary, cleaning showers or a bottom flow are used in the saveall channel.

The functional separator can be implemented in various ways. A cyclone 26 is advantageously used as the separator 16. With a cyclone, a good separating capacity and a compact structure are achieved. In addition, high flow speeds can be used with a cyclone without reducing the separating capacity. A cyclone is also easy to keep clean and, above all, it is easy to empty. Similarly, the air flow means can be implemented in various ways. According to the invention, the air flow means 14 are advantageously composed of an air amplifier 27, which is adapted as the air exhaust connection 18 of the cyclone 26. Such a construction further simplifies the design of the conditioning equipment as well as reduces pressure losses. Figure 3 shows a cross-sectional view of the cyclone 26. The various parts of the cyclone are dimensioned mainly based on the size and amount of particles as well as the desired separating capacity. The air amplifier 27 can be connected directly to the top part of the cyclone 26. Figure 3 shows also the access hole 29 to the cyclone 26 for the flow connection 19 and, in the bottom part of the cyclone 26, a mixture separated from air, which consists mainly of matter and fluid. In addition, the flow connection 19 is so adapted that the air flow arrives tangentially .

Figure 4 shows the operating principle of the cyclone 26. The air flow forms a spiral-shaped path toward the bottom of the cyclone 26. The peculiar path is mainly due to the geometrical construction of the cyclone 26. In a spiral air flow the matter and fluid to be separated are thrown onto the walls of the cyclone 26 and run down to the bottom of the cyclone 26 and further to the discharge connection 20. The air flow being cleaned forms a new vortex at the bottom, at the center of the cyclone 26, rising upward and exiting the cyclone 26 via the air exhaust connection 18. It has been noticed in tests that the separating capacity of the cyclone is so good that the air exiting from the air amplifier is almost perfectly dry. Thus separate exhaust filters are unnecessary, which further reduces pressure losses. In other words, the capacity of the air ampli- fier can be utilized in the best possible way to create a suction effect and to generate an efficient air flow. According to the invention, the air flow means are so arranged that the flow speed is at least 10 m/s at the cleaning head. In this way the matter and the fluid sprayed to the fabric can be reliably collected. At the same time, a sufficient flow speed is obtained in the cyclone whereby its separating capacity can be maximally utilized.

Figure 1 shows the principle of the energy line assembly 30 of the conditioning equipment. Firstly, high-pressure fluid, such as fresh water, is led to the cleaning head 10, for the nozzle elements 13. The supply line of fluid is represented here by a broken line. Secondly, the air amplifier 27 requires air pressure. Here the air pressure supply line is represented by a dot-and-dash line. In practice, the energy line assembly is so formed that various lines permit moving the cleaning head from one fabric edge to the other. The energy line assembly also includes means for providing the traversing movement. As the traversing mechanism, any known technique can be used. Another item requiring air pressure is the air blow device, such as an air knife/air comb 31, which, according to the invention, is arranged outside the suction effect zone of the cleaning head 10, after the cleaning head 10 in the travel direction of the fabric 12. The air blow device, advantageously an air knife 31, prevents the matter from spreading out from between the cleaning head 10 and the fabric 12. In most cases an air knife is unnecessary and it is used only when required, such as in problem conditions. For example, in the unsupported part of the fabric, an air knife is advantageous because it prevents mist from spreading forward in the fabric cycle.

In the applications of Figures 1 and 2a, the cleaning head 10 is arranged in the unsupported part of the fabric 12, which is impossible in most known apparatuses. Particularly when the fabric 12 is a dryer fabric, the cleaning shower can be di- rected through the wire in this application. In this case the conditioning equipment still includes a saveall tray 32, which is adapted to be located on a different side of the fabric 12 relative to the cleaning head 10. Thus a significant portion of the fluid and at least part of the matter goes through the wire to the saveall tray 32 while the rest of the matter and fluid goes to the separator. In such conditions, a surprisingly small separator can be used. Cleaning showers or a bottom flow are used in the saveall tray as well. In addition, the saveall tray has a suitable gradient and it can empty into the above men- tioned collecting pit.

In the cleaning head, needle or fan nozzles or combinations of these can be used as nozzle elements. Particularly, a good separating capacity can be achieved with a cyclone when clean and dry air is removed from the top part of the cyclone. By- using a cyclone that moves along with the cleaning head and an air amplifier, a separate vacuum system is avoided as well as long pipelines and large channels. The conditioning equipment according to the invention has a simple construction and allows fast installation. In addition, the conditioning equipment is almost non-soiling and the separated matter and water are removed by the gravitational force. The efficiency of the conditioning equipment is also clearly better compared to known devices. Based on tests, earlier cleaning capacity can be achieved with a lower compressed air consumption than earlier. In addition, the fabric can be conditioned by spraying water through it. In known devices, conditioning is possible only against a roll to avoid splashing. When utilizing a separator, large amounts of air and high flow speeds can be used without the risk of misting.

The height of a cyclone according to the invention designed for the conditioning of a conventional fabric can be in the range of about 300 - 1000 mm while the diameter is in the range of about 100 - 300 mm. For the cleaning head, needle nozzles of 0,1 - 0,3 mm could be used supplying water at a pressure of 100 - 500 bar. In practice, the water consumption would then be less than one liter per minute. In case the cleaning head moves across a ten-meter wide fabric at a speed of ten millimeters per second, the separator collects about thirty liters of water per one fabric width. Figure 2b shows an enlarged view of the cleaning head 10 according to the invention. Here nozzle elements 13 are connected to the frame of the cleaning head 10 by quick clamping. Thus the nozzle elements can be replaced in less than a minute.

In addition, the cleaning head according to the invention is small in size whereby its positioning is easier than before. Furthermore, the flow connection is completely unrestrained as the nozzle elements are located immediately before the flow connection in the travel direction of the fabric. The movement of the fabric transports the matter detached from the fabric surface naturally toward the flow connection. Particularly a cyclone utilizes a high air flow calming it down at the same time and providing thus separation of the matter and fluid from air.

The consumption of compressed air in the earlier equipment of the applicant is about 800 standard liters per minute while the pressure is up to 5 bar. The conditioning equipment presented now operates equally efficiently with a much lower compressed air consumption. At the same time, the pressure requirement is smaller than before so that the conditioning equipment can be installed in old mills as well. Regardless of the clearly lower power requirement, the cleaning capacity of the conditioning equipment according to the invention, however, is better than earlier. Instead of an air amplifier, another suitable vacuum generator can be used, such as .an ejector, a pressure amplifier, a venturi pipe or a vacuum blower.

Claims

1. Conditioning equipment for the fabric of a fiber web machine with the conditioning equipment including - at least one cleaning head (10) adapted to be moveable back and forth in the transverse direction to the fabric (12) by means of guiding means (11),

- nozzle elements (13) arranged in the cleaning head (10) for supplying fluid to the fabric (12), - air flow means (14) for creating a suction effect in the cleaning head (10), and

- discharge means (15) connected to the cleaning head (10) for transferring the supplied fluid and the matter detached from the fabric (12) and collected by the suction effect away from the cleaning head (10), characterized in that the discharge means (15) include a functional separator (16) for separating matter and fluid from air.

2. Conditioning equipment according to claim 1, characterized in that the separator (16) includes an inlet connection (17) and an air exhaust connection (18), and the cleaning head (10) is connected to the inlet connection (17) while the air flow means (14) are connected to the air exhaust connection (18) .

3. Conditioning equipment according to claim 1 or 2, characterized in that the separator (16) is supported to the guiding means (11) and thereby adapted to be moveable back and forth together with the cleaning head in the transverse direction to the fabric (12) .

4. Conditioning equipment according to claim 2 or 3, characterized in that, in addition to the inlet connection (17) and the air exhaust connection (18), the separator (16) includes a discharge connection (20), with closing means (21) arranged therein, for removing the separated matter and fluid.

5. Conditioning equipment according to claim 4, characterized in that the discharge means (15) further include a collector (23) adapted underneath the discharge connection (20), the collector being a saveall channel (25) that extends across the fiber web machine and/or a collecting pit (24) located at the edges of the fiber web machine.

6. Conditioning equipment according to any of claims 1 - 5, characterized in that the separator (16) is a cyclone (26) .

7. Conditioning equipment according to claim 6, characterized in that the air flow means (14) are composed of an air amplifier (27) which is adapted as an air exhaust connection (18) of the cyclone (26) .

8. Conditioning equipment according to any of claims 1 - 7, characterized in that an air blow device (31) is arranged outside the suction effect zone of the cleaning head (10) , after the cleaning head (10) in the transfer direction of the fabric (12) .

9. Conditioning equipment according to claim 8, characterized in that the air blow device (31) is an air comb or an air knife.

10 . Conditioning equipment according to any of claims 1 - 9 , characteri zed in that the condit ioning equipment further include s a saveal l ( 32 ) , whi ch i s adapted to be l ocated on a different side of the fabric ( 12 ) relative to the cleaning head ( 10 ) .