EP2327834A1

EP2327834A1 - Arrangement and method for removing oil from a shoe press in a fiber web machine

Info

Publication number: EP2327834A1
Application number: EP09177165A
Authority: EP
Inventors: Jorma Snellman
Original assignee: Metso Paper Oy
Current assignee: Metso Paper Oy
Priority date: 2009-11-26
Filing date: 2009-11-26
Publication date: 2011-06-01
Anticipated expiration: 2029-11-26
Also published as: EP2327834B1

Abstract

The invention relates to an arrangement for removing oil from a shoe press in a fiber web machine. The shoe press includes a fixed beam (10) and a loading shoe (11) arranged movably on the beam (10). The shoe press further includes a flexible belt (13) interacting with the loading shoe (11) and an oil removal equipment (17) with an inlet opening (18), which is arranged close to a closing nip (19) formed by the loading shoe(11) and the belt (13). The arrangement includes a wipe (21) arranged in connection with the oil removal equipment (17) and adapted in contact with the inner surface of the belt (13) for collecting particles to the inlet opening (18). The invention relates also to method for removing oil from a shoe press in a fiber web machine.

Description

The invention relates to an arrangement for removing oil from a shoe press in a fiber web machine, which shoe press includes

a fixed beam,
a loading shoe arranged movably on the beam,
a flexible belt interacting with the loading shoe, and
an oil removal equipment with an inlet opening, which is arranged close to a closing nip formed by the loading shoe and the belt.

The invention also relates to a method for removing oil from a shoe press in a fiber web machine.
European patent number EP1238149B1 discloses a shoe press. The loading shoe has a pocket through which oil is fed between the belt and the loading shoe. Oil acts as a lubricant and a coolant. Thus oil reduces friction and heat generation. In practice, more oil is fed than the closing nip can receive. In other words, majority of the oil circulating on top of the inner surface of the belt must be removed before the closing nip. The warmed excess oil is removed with an oil removal equipment arranged close to a closing nip.
The known oil removal equipment is arranged to receive oil squirting from the loading shoe when rushing against it. Also the inlet opening is directed towards the loading shoe and the oil removal equipment is far from the inner surface of the belt. Thus the oil removal equipment is incapable to remove particles from the oil before the nip. During the operation of the shoe press, the belt may start to delaminate for some reason. These thin, but sometimes very large delaminated pieces can accumulate to a thick mass. When this thick mass or lump goes to the closing nip, i.e. between the loading shoe and the belt, the belt will receive a shocking impact which damages the belt. These impacts will increase the delamination of the inner surface of the belt or may even cause an breaking of the belt. In addition, this kind of particles may be gathered, for example, on top of the beam. After the belt change, the particles may again join the circulating oil and end to the closing nip causing damages to the brand-new belt. Also paper wads between the outer surface of the belt and the counter element/roll are a major factor for delaminating of the belt.
The invention is intended to create a new type of arrangement for removing oil from a shoe press in a fiber web machine by means of which arrangement problems caused by particles inside the shoe press can be avoided in a simple way. The characteristic features of the arrangement according to the invention are that the arrangement includes a wipe arranged in connection with the oil removal equipment and adapted in contact with the inner surface of the belt for collecting particles. By aid of the wipe also the particles stuck onto the inner surface of the belt can be removed and collected securely. The invention is also intended to create a new type of method for removing oil from a shoe press in a fiber web machine, which can be easily implemented in the known shoe presses. The characteristic features of the method according to the invention are that a wipe, arranged in connection with the oil removal equipment, is used and particles from oil are collected by aid of the wipe. Advantageously the oil removal equipment and the wipe cooperate making the oil and particle removal easy and secure. When particles, especially pieces delaminated from the belt, can be collected, the risk of belt damage will substantially decrease.
In the following, the invention is described in detail with reference to the accompanying drawings showing some embodiments of the invention, in which

Figure 1: shows in cross section one embodiment of the arrangement according to the invention,
Figure 2a: shows a partial enlargement of Figure 1,
Figure 2b: shows a close detail of the arrangement according to the invention,
Figure 3a: shows a front and side view of the first preferred embodiment of the wipe according to the invention,
Figure 3b: shows a front and side view of the second preferred embodiment of the wipe according to the invention,
Figure 3c: shows a front and side view of the third preferred embodiment of the wipe according to the invention.

Figure 1 shows in cross section a shoe press according to the present invention. The shoe press is used mainly in the press section of the fiber web machine. This kind of machines are, for example, paper machines, cardboard machines or tissue machines. As a load-bearing structure, the shoe press includes a fixed beam 10. In other words, the beam 10 is stationary. The shoe press also includes a loading shoe 11 arranged movably on the beam 10. The loading shoe 11 is supported by a loading elements 12, which are functional hydraulic pistons. Thus the loading shoe 11 can be moved hydraulically in relation to the beam 10. The shoe press further includes an endless, flexible belt 13, which is arranged to interact with the loading shoe 11. In other words, the inner surface of the belt is in contact with the loading shoe. Correspondingly, the outer surface of the belt interacts with a counter-roll 14, thereby forming a press nip. Through this nip the fiber web is led together with one or two felts for removing water form the fiber web. In use the belt 13 rotates around the fixed beam 10. In Figure 1 the direction of rotation of the belt 13 is illustrated with a thick arrow.
For forming a hydrostatic/hydrodynamic bearing, oil is fed between the loading shoe and the belt. In this embodiment, the loading shoe 11 has a distribution pocket 15 to which oil is fed via ducts 16 as shown in Fig. 2a or there is an oil shower pipe before or after the nip. In the direction of the rotation of the belt 13, there is an oil removal equipment 17 before the loading shoe 11. The oil removal equipment 17 has an inlet opening 18, which is arranged close to a closing nip 19 formed by the loading shoe 11 and the belt 13. Thus the excess oil squirting from the loading shoe can be gathered and led out of the shoe press. The shoe press is also called as an extended-nip press or a long-nip press.
Here, the oil removal equipment 17 is connected with the loading shoe 11 and it has an oil-removal pipe 20, which has variable length. Thus the oil removal equipment moves together with the loading shoe. According to the invention, the arrangement includes a wipe 21 arranged in connection with the oil removal equipment 17 and adapted in contact with the inner surface of the belt 13 for collecting particles. Thus random particles, for example, pieces delaminated from the belt can be easily removed out of the shoe press. Especially the wipe detaches particles also from the inner surface of the belt when contacting the belt. All the hazardous particles are removed by the wipe before they enter the closing nip 19.
As already mentioned, the oil removal equipment 17 includes a collecting tray 22 which is advantageously arranged firmly in relation to the loading shoe 11. Thus the distance between the loading shoe 11 and the collecting tray 22 remains constant. According to the invention, the wipe 21 is advantageously arranged as a part of the collecting tray 22. In this way all three components, i.e. the loading shoe and the collecting tray 22 and the wipe move as a unit. This keeps the conditions for removing oil and particles favourable. Another possible installation point for the wipe is marked with X in Fig. 1. Then the wipe would be installed in connection with a support shoe contacting the inner surface of the belt for keeping the wipe in a constant distance from the belt. There would also be an auxiliary tray in connection with the wipe and the support shoe for collecting the particles. The auxiliary tray would be without any oil removal equipment. Thus the collected particles would be removed from the auxiliary tray during the belt change. In the embodiment shown in Fig. 2b, the arrangement also includes a sieve part 23 arranged to allow oil running to the closing nip 19 in spite of the wipe 21. Correspondingly, the sieve part allows oil to run back to the inlet opening from the loading shoe. However, the particles will end to the collecting tray and therefrom via the oil-removal pipe 20 out of the shoe press. When particles arrive on the inner surface of the belt towards the loading shoe, the wipe will scratch the particles and then the sieve part directs the particles to the collecting tray (the arrow in broken line in Fig. 2b). The wipe directs also the oil flow, a part of which passes the sieve part. The lowest arrow illustrates this oil flow in Fig. 2b. The possible excess oil will also return through the sieve part to the collecting tray. The upmost arrow illustrates this return oil flow in Fig. 2b.
To achieve a good wiping result, the wipe should always be in contact with the inner surface of the belt. According to the invention, the wipe 21 has a flexible part 24 for conforming to the transformation of the belt 13. Advantageously, the flexible part is adapted in such way that it tends to straighten the wipe. Thus the contact to the inner surface always remains. The flexible part of the wipe also allows the movement of the collecting tray. Also the pressure of the incoming oil will press the wipe against the belt.
The above mentioned function can be achieved also by a pivotally arranged wipe (not shown). Also simple loading means can be used. For example, the known loading hoses are applicable. However, it is advantageous to arrange the sieve part 23 as the flexible part 24 of the wipe 21. This makes the structure of the wipe very simple and compact. For example, the wipe 21 consists of a tip part 25 arranged to contact the inner surface 26 of the belt 13 and a flexible sieve part 23 arranged as a fixed part of the collecting tray 22. Advantageously, the tip part 25 is of a softer material than said inner surface 26 in order to avoid the damage of the belt.
The dimensioning and the material of the wipe can vary in different embodiments. Also the viscosity of the oil contributes especially to the mesh size. However, the sieve part 23 has such a mesh size that particles over 1 mm², are collected. This kind of sieve part is dense enough to collect the majority of the particles. The smaller impurities will be removed from the oil elsewhere.
The wipe according to the invention is shown in Fig. 3a. Here the functional wiping part is a narrow metal strip attached to a flexible sieve mesh 27. The sieve mesh 27 may be resilient plastic, for example. Here the metal strip is thinner than the sieve mesh. In Fig. 3b, a flexible plate act both as wipe and sieve part. Here sieving function is achieved with a plurality of through holes 28. The holes can be circular or have an other shape. Also the thickness of the plate may vary as well as its material. For example, a plastic plate with PTFE-coating is light and resilient and durable. Fig. 3c illustrates the third embodiment of the wipe according to the invention. Here the functional wiping part is a narrow plastic strip attached to a plurality of flexible wires 29. The wires form a kind of baleen or grid acting as the sieve part. The second ends of the wires are attached to a connecting strip 30, which is used for fastening the wipe to the collecting tray. All the three above mentioned wipes can easily be retrofitted to the collecting trays already in use. In new installations, the wipe and the sieve part can be even more integrated as a part of the collecting tray.
The excess oil is removed from a shoe press in a fiber web machine for cooling and filtration. For example, the known shoe presses require several cubic metres oil, which is circulated continuously. Inside the shoe press, the oil is usually removed before a closing nip formed by the loading shoe and the belt by aid of an oil removal equipment with an inlet opening, as described earlier. According to the invention, a wipe, arranged in connection with the oil removal equipment, is used and particles from oil are collected by aid of the wipe. In addition, advantageously the wipe is loaded against the inner surface of the belt. Thus, even particles stuck onto the inner surface can be released and removed together with the oil. From the oil, particles are filtered in the oil tank. Also a separate detector may be used in the return oil pipe. The applicant has a such detector called BeltSense™ for particle detection.
When the fiber web machine is started up for operation, the inner surface of the belt is provided with an oil film for lubrication the contact between the belt and the loading shoe. The oil acts also as coolant. In operation, there is a slight over pressure inside the shoe press. Also in the pipe there is usually a under pressure. Thus the oil collected in the collecting tray will be removed from the shoe press together with the wiped particles. Also the kinetic energy of the squirting excess oil will assist the removing of the oil and the particles.
The arrangement according to the invention can be easily implemented in the known shoe presses. Even the retrofitting of the simple wipe is possible. The flexible wipe maintains its functionality even if the belt transforms or oil collecting tray moves along with the loading shoe. The wipe can be made from various materials and the sieve can be constructed in many ways. Advantageously the wipe and the sieve are closely connected to each other and more advantageously the wipe and the sieve are integrated with the oil collecting tray as a single unit.

Claims

Arrangement for removing oil from a shoe press in a fiber web machine, which shoe press includes
- a fixed beam (10),

- a loading shoe (11) arranged movably on the beam (10),

- a flexible belt (13) interacting with the loading shoe (11),
and

- an oil removal equipment (17) with an inlet opening (18), which is arranged close to a closing nip (19) formed by the loading shoe(11) and the belt (13),
characterized in that the arrangement includes a wipe (21) arranged in connection with the oil removal equipment (17) and adapted in contact with the inner surface of the belt (13) for collecting particles to the inlet opening (18).
Arrangement according to Claim 1, characterized in that the oil removal equipment (17) includes a collecting tray (22) arranged firmly in relation to the loading shoe (11), and the wipe (21) is arranged as a part of the collecting tray (22).
Arrangement according to Claim 1 or 2, characterized in that the wipe (21) has a flexible part (24) for conforming to the transformation of the belt (13).
Arrangement according to any of Claims 1 - 3, characterized in that the arrangement also includes a sieve part (23) arranged to allow oil running to the closing nip (19) in spite of the wipe (21).
Arrangement according to Claim 4, characterized in that sieve part (23) is arranged as the flexible part (24) of the wipe (21).
Arrangement according to Claim 4 or 5, characterized in that the sieve part (23) has such a mesh size that particles over 1 mm², are collected.
Arrangement according to any of Claims 4 - 6, characterized in that the sieve part (23) is a plate equipped with a plurality of through holes (28) or a sieve mesh (27), both made of resilient plastic.
Arrangement according to any of Claims 1 - 7, characterized in that the wipe (21) has a tip part (25) arranged to contact the inner surface (26) of the belt (13), which tip part (25) is of a softer material than said inner surface (26).
Method for removing oil from a shoe press in a fiber web machine, which shoe press comprises a loading shoe (11) arranged movably on a fixed beam (10) and a flexible belt (13) interacting with the loading shoe(11), and according to the method oil is removed before a closing nip (19) formed by the loading shoe (11) and the belt (13) by aid of an oil removal equipment (17) with an inlet opening (18), characterized in that a wipe (21), arranged in connection with the oil removal equipment (17), is used and particles from oil are collected by aid of the wipe (21).
Method according to Claim 9, characterized that the wipe (21) is loaded against the inner surface (26) of the belt (13).
Method according to Claim 9 or 10, characterized in that the arrangement according to any of Claims 1 - 8 is used.