Drying and gas or vapor contact with solids – Apparatus – Rotary drums or receptacles
Reexamination Certificate
2000-09-29
2002-05-07
Walberg, Teresa (Department: 3742)
Drying and gas or vapor contact with solids
Apparatus
Rotary drums or receptacles
C034S456000, C162S360300
Reexamination Certificate
active
06381868
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 199 46 971.7, filed on Sep. 30, 1999, the disclosure of which is expressly incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a device for dewatering a material web, in particular a paper or cardboard web, by driving water out of the material web by gas pressure. the device includes having at least one pressure chamber limited by at least four rolls arranged parallel to one another and arranged to form a pressure chamber of which a pressurized gas can be introduced and through which the material web can be guided.
2. Discussion of Background Information
In such a process, instead of a mechanical compression of the material web, the pressurized gas is pressed through the material web and the water is driven out of the material web in this manner.
SUMMARY OF THE INVENTION
An aspect of the invention is to produce a device of the above-mentioned type for dewatering a material web that can be used in as many functions as possible. This device for dewatering a material web, in particular a paper or cardboard web, by driving water out of the material web using gas pressure, having at least one pressure chamber limited by at least four rolls arranged parallel to one another into which a pressurized gas can be introduced and through which the material web can be guided, with the positions of the rolls being displaceable relative to one another. Moreover, the positions of the rolls can be adjusted relative to one another.
According to the invention, the geometry and the form of the pressure chamber can be changed by the adjustability of the relative arrangement of the rolls. This creates the possibility of deliberately varying the length of the path traveled by the material web inside the pressure chamber.
According to the invention, a dwell time of the material web inside the pressure chamber can be set to any desired value by adjusting the roll position. The dewatering device according to the invention can thus be used in many different functions and for a plurality of material types. In a machine for producing a paper or cardboard web, for example, the requirements for different types of paper or cardboard can be taken into account using only one dewatering device according to the invention in that, by adjusting the relative roll positions, the necessary dwell time for the respective web to be dewatered inside the pressure chamber can be set.
It is preferred for the positions of the rolls to be adjustable while maintaining a pressure chamber that is limited by the rolls at all times. By adjusting the roll positions, the pressure chamber is maintained as such. Only the geometry and/or form of the pressure chamber is changed by adjusting the rolls.
According to another preferred embodiment of the invention, two rolls lying across from one another can each automatically track an adjusting movement of at least one of the two other rolls. Thus, it is necessary to adjust the position of only one single roll because the automatic tracking of the two rolls that are facing one another assures that the desired roll configuration is set at the end of the adjusting movement.
It is preferred for each of the two rolls lying across from one another to be prestressed in contact with both of the other rolls, with the distance between the two other rolls being adjustable.
The prestressing causes the two rolls lying across from one another to be pressed against both of the other rolls and to remain in contact with the other rolls, thereby maintaining a pressure chamber limited by all four rolls, when the distance between the other two rolls is changed for the purpose of setting the desired roll configuration. It is preferred for both prestressed rolls to have a smaller diameter than the other two rolls.
According to one variant of the invention, the prestressing of the rolls can be achieved in that the prestressed rolls are each coupled by at least one prestressing device to a stationary support. The prestressing devices can, for example, be elastically deformable and, e.g., embodied as arrangements of pressure springs, each of which are supported at one end on the stationary support and are connected with the respective roll on the other end.
According to another variant of the invention, the prestressing of the rolls is achieved in that the rolls are coupled with one another by way of at least one prestressing device. The prestressing device, which is embodied, for example, as being elastically deformable and, e.g., embodied as a tension spring, attempts to move the two rolls toward one another, whereby the two prestressed rolls are pressed against both of the other rolls.
The prestressing devices can also be embodied as hydraulic or pneumatic cylinders. The contact force of the roll can be predetermined thereby using the fluid and/or gas pressure, in which connection the fluid and/or gas can be adjusted by a control and/or regulation device, in particular dependent upon the pressure prevailing in the pressure chamber. With such an adjustable prestressing device, the mechanical pressure on the material web in the entrance nip and exit nip of the pressure chamber can be varied. In this manner, a pre- and/or post compression of the material web is achieved whose effectiveness is deliberately adjustable.
In all variants of the invention listed above, the prestressed rolls are kept permanently in contact with the two other rolls so that, in the case of an adjusting movement, at least one of the two other rolls can follow the prestressed roll making the adjusting movement and a pressure chamber with the desired geometry and/or form that is limited by all four rolls is present at the end of the adjusting movement.
The present invention further provides a process for dewatering a material web, in particular a paper or cardboard web, by driving water out of the material web by gas pressure, in which a pressurized gas is introduced into at least one pressure chamber and the material web is guided through the pressure chamber. The area of effect of the pressure chamber is changed in the travel direction of the material web, in particular its effective length, for the purpose of adjusting the dewatering capacity of the area of effect of the pressure chamber.
With such a process, the dwell time of the material web in the pressure chamber, and thus the dewatering capacity, can be adjusted in the desired manner by changing the area of effect of the pressure chamber.
Advantageous embodiments of the invention are also provided in the claims, the description, and the drawings.
According to an aspect of the invention an apparatus for dewatering a material web is provided which includes at least one pressure chamber formed by at least four substantially parallel rolls, a device arranged to introduce a pressurized gas into the at least one pressure chamber, and the at least four substantially parallel rolls being displaceable relative to one another to change an effective area of the at least one pressure chamber. The material web is guided through the at least one pressure chamber.
According to another aspect of the present invention the material web is one of a paper and cardboard web. Additionally, other aspects of the present invention include driving water out of the material web using the pressurized gas. In another aspect of the present invention positions of the at least four substantially parallel rolls are adjustable while a pressure within the at least one pressure chamber is maintained.
According to a further aspect of the present invention a first pair of rolls of the at least four substantially parallel rolls are configured across from one another and a position of the first pair of rolls is adopted to follow a movement of at least one of the remaining rolls of the at least four substantially parallel rolls.
In another aspect of the present invention, the invention includes at least one prestressi
Beck David
Begemann Ulrich
Böck Karl Josef
Dahl Hans
Elenz Thomas
Campbell Thor
Greenblum & Bernstein P.L.C.
Voith Sulzer Papiertechnik Patent GmbH
Walberg Teresa
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