This application is the U.S. national phase of PCT Appln. No. PCT/AT2011/000424 filed on Oct. 13, 2011, which claims priority to AT Patent Application No. A 1783/2010 filed on Oct. 27, 2010, the disclosures of which are incorporated in their entirety by reference herein.
The subject of this invention is a suction roll for dewatering a fibrous web, having a rotatable and perforated suction roll jacket and a suction box. The suction box is located in the interior of the suction roll and connected to a negative pressure source in such a way that said suction box applies a negative pressure to an inner surface, that is delimited by seals, of the suction roll jacket, thus enabling a defined surface region of the suction roll to be aspirated.
A traditional suction roll is shown in
The object of the invention is thus to optimize a suction roll in such a way that the filtrate can reliably be extracted from the suction roll.
This object is achieved by a suction roll with an optimized suction box. The suction box herein has a first and a second suction channel. The first suction channel extends in the interior of the suction roll substantitally along the axis of the suction roll, and the second suction channel extends in the interior of the roll along the inner surface of the suction roll jacket. The second suction channel is sealed off by seals which fit to the inside of the suction roll jacket. According to the invention, the first and the second suction channel are interconnected by at least one connecting channel. This connecting channel preferably extends in a radial direction (in relation to the geometry of the roll). It is further provided that the at least one connecting channel leads into the first suction channel above a collection region of the first suction channel, such that extracted water can accumulate in the collection region and does not run off back through the connecting channel.
This embodiment of the suction box according to the invention enables a significantly reduced aspirated internal volume of the suction roll to be achieved, as compared to traditional suction boxes. As a result of the reduced volume, high air speeds, which reliably carry along the extracted filtrate, occur in particular in the second suction channel.
It is advantageous that two press nips (pressure points A, B) of the suction roll are aspirated by the second suction channel, as the filtrate accruing at two locations is thus extracted by a single extraction.
In a favorable embodiment, retaining strips which extend in the running direction of the machine (C) are located in the interior of the second suction channel. This enables the dewatering performance of the suction roll to be improved yet further. The purpose of these retaining strips is to prevent a transverse flow in relation to the running direction in the interior of the suction zone of the second suction channel.
By means of the retaining strips, a non-aspirated region within the suction zone can be prevented. Furthermore this also achieves that the holes in the suction roll jacket cannot be covered by material, as they are being constantly rinsed with filtrate.
The retaining strips preferably have some mechanical play in relation to the suction roll jacket, that is to say that they do not form a seal against the suction roll jacket. The mechanical play of the suction strips in relation to the suction roll jacket may also be adjustable by means of an adjustment element.
In a favorable embodiment, the retaining strips extend from the second suction channel into the connecting channel which connects the second suction channel with the first suction channel. This further improves the guidance of the flow.
It is also conceivable that a further suction channel is located in the interior of the roll of the suction roll, through which a further defined surface region of the suction roll is aspirated. This suction zone can, for instance, be used for vacuum drying a cover. For the purpose of homogenizing the aspiration across the width of the machine, retaining strips may also be located in the further suction channel.
In the following, the invention is explained with reference to drawings, in which:
Identical reference signs in the respective figures refer to identical components.
In the case of this suction roll, there is the risk of the filtrate not being able to be completely suctioned off from the suction roll at higher speeds and of the roll 20 thus having a tendency to “spatter”. This is dependent on the vacuum and on the circumferential speed.
In this example, two press nips A and B are aspirated through the second suction channel 4; the corresponding counter-rolls are not shown.
The invention, of course, also comprises exemplary embodiments in which retaining strips 10 are only located in the second suction channel 4.
In the present example, the retaining strips 10 extend into the connecting channel 9 to guide the filtrate from the suction zone directly to the upper part of the first suction channel 3, from where it is extracted transversely from the suction box 7.
Number | Date | Country | Kind |
---|---|---|---|
A 1783/2010 | Oct 2010 | AT | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/AT2011/000424 | 10/13/2011 | WO | 00 | 4/12/2013 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2012/054943 | 5/3/2012 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
2204780 | Thaler | Jun 1940 | A |
2714342 | Beachler | Aug 1955 | A |
2772606 | Kelly | Dec 1956 | A |
3018825 | Han et al. | Jan 1962 | A |
5034100 | Sides | Jul 1991 | A |
6402896 | Nikulainen et al. | Jun 2002 | B1 |
6592721 | Anderson et al. | Jul 2003 | B1 |
6616810 | Brogyanyi et al. | Sep 2003 | B1 |
6682632 | Nikulainen et al. | Jan 2004 | B2 |
20030008757 | Nikulainen et al. | Jan 2003 | A1 |
20130095989 | Eichler et al. | Apr 2013 | A1 |
Number | Date | Country |
---|---|---|
4103040 | Aug 1992 | DE |
29822227 | Feb 1999 | DE |
10329808 | Apr 2004 | DE |
Entry |
---|
DE 4103040, Freiber Paper, machine translation, 1992. |
DE 10329808,Metso Paper, machine translation, 2004. |
International Search Report for PCT/AT2011/000424, English translation attached to original, Both completed by the European Patent Office on Mar. 15, 2012, All together 5 Pages. |
Number | Date | Country | |
---|---|---|---|
20130213879 A1 | Aug 2013 | US |