Paper making and fiber liberation – Processes and products – Running or indefinite length work forming and/or treating...
Reexamination Certificate
1999-09-10
2001-09-25
Silverman, Stanley S. (Department: 1731)
Paper making and fiber liberation
Processes and products
Running or indefinite length work forming and/or treating...
C162S359100, C162S290000, C162S361000, C162S357000, C162S297000, C162S206000, C034S117000, C034S119000, C034S123000, C034S124000
Reexamination Certificate
active
06294050
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 198 41 768.3, filed on Sep. 11, 1998, 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 method for drying a material web and to a drying end of a machine for the production of a material web, and in particular, a paper or cardboard web.
2. Discussion of Background Information
During drying, in a known multi-cylinder drying end, a paper web is guided over a plurality of steam-heated cylinders and often also over suction rolls. At the beginning of the drying process, when the paper web still does not have adequate strength, problems frequently occur with regard to web guidance which are often attributed to the fact that the still-moist web continues to adhere to the smooth contact surfaces of the drying end, the smooth surfaces being necessary for adequate heat transfer. This adhesion often results in breakage of the web as well as excessive stretching of the edges of the web. Care must thus be taken so that drying occurs more slowly, which means that the necessary drying end must have a longer overall path. These problems are more pronounced at higher web speeds.
SUMMARY OF THE INVENTION
The present invention provides a drying end of a machine for the production of a material web, and a method of drying a material web. The drying end of a machine for the production of a material web has at least one impact flow drier configured to bombard at least one surface of the material web with at least one of hot air and hot steam impact flow. The material web may be paper or cardboard. Also, an open support surface over which the material web is guided by the surface opposite the surface bombarded with the impact flow, may be provided. A steam suction device may be provided on at least one impact flow drier, the impact flow drier being configured to simultaneously dry the material web and remove steam.
The drying end may further include a cover wire positioned between the material web and the impact flow drier, wherein the cover wire and the material web may be guided together over the support surface. The invention may further have a support roll over which the material web may be guided, and wherein the open support surface may be the surface of the support roll, a covering over the support roll, a coating of the support roll or a continuous belt adapted for guiding over the support roll. The support roll may have an external diameter in the range from approximately 2 meters to approximately 10 meters.
Additionally, the open support surface may include a surface of a continuous belt for guidance over the support roll, the continuous belt having an air-permeable wire or air-impermeable transport belt. The open support surface may also include a shrink wire installed on the support roll. Also, the support roll may have a solid sleeve design or a spoke/lattice design.
The open support surface may further include a surface of a support belt configured to be guided over a plurality of support rolls. Also, the support rolls may be arranged in an arc. The open support surface may further be divided into a plurality of sections, each section being flat. The support surface may further include a removal zone, and may bombard the material web with compressed air through the support surface at least in the removal zone, whereby the web may be removed from the support surface.
Further, the support belt may be constructed of metal or plastic. The support belt may be air-impermeable or constructed of an air-impermeable fabric. The support belt may be configured to be guided in the shape of a polygon, and may lie in either a plane or a curve.
The support roll may have perforations or a lattice structure, and may guide the material web thereover, the support roll bombarding the web with compressed air. The support roll may further include a removal zone, and the support roll may be bombarded on the inside thereof with compressed air at least at the removal zone, whereupon the web may be removed from the support surface.
The cover wire may be positioned between the material web and the impact flow drier, wherein the cover wire and the material web may be guided together over the support surface, such that the web and the cover wire may be removed from the support roll. Also, the cover wire may be constructed of metal or plastic.
The temperature of the compressed air may be higher than approximately 20° C. Also the hot air and hot steam impact flow may have a temperature in the range from approximately 150° C. to approximately 450° C., and may further be generated by an impact flow drier. The flow speed of the hot air and hot steam impact flow may be in the range from approximately 60 meters/second to approximately 120 meters/second.
Also, the impact flow drier may include a plurality of nozzles and/or a drier hood. Each nozzle may by spaced by a fixed and identical distance from the material web during operation. The distance of each the nozzle from the material web may be in the range from approximately 10 mm to approximately 50 mm.
The invention may further include at least two support rolls positioned in series in the direction of web travel, each support roll being operatively arranged with a respective impact flow drier. Also, each of the support rolls may have a different diameter. The support rolls may lie in a single plane or along a curved surface.
At least one impact flow drier may have a drier hood subdivided into zones according to a direction of web travel or at right angles to a direction of web travel. The impact flow drier may be positioned above the material web and may be operatively arranged with a respective support surface positioned below the material web. The impact flow drier may be positioned below the material web and may be operatively arranged with a respective support surface positioned above the material web. Also, at least one impact flow drier may be provided in a starting zone.
The material web may be simultaneously bombarded on both surfaces in at least one zone by hot air or hot steam impact flow. Additionally, the material web may be guided through at least one zone between two wire belts. The material web may further be guided through the zone along a linear or curved path. Also, the wire belt may be guided over a plurality of support rolls. The wire belt may be constructed of metal or plastic.
The invention may further include at least one drying group having at least one drying cylinder, wherein an impact flow drier may be located upstream of the at least one drying group in a direction of web travel, and the material web may have a solids content which may be greater than approximately 55% to approximately 70% upon reaching the at least one drying cylinder. Also, a one-row drying group and at least one two-row drying group may be included.
An end zone may be provided, wherein an impact flow drier may be provided in the end zone. Also, an evaporation zone may be provided, wherein an impact flow drier may be provided at the evaporation zone.
Further, at least two impact flow driers may be positioned in series in a direction of web travel, the flow driers bombarding the material web from opposite web surfaces with hot air or hot steam impact flow. Alternatively, the flow driers may bombard the material web from one web surface.
At least two intermediate impact flow driers positioned opposite each other and configured to bombard the material web from opposite surfaces may be provided. Also, at least one intermediate impact flow drier may be provided that bombards the material web from opposite web surfaces with hot air or hot steam impact flow, and the intermediate impact flow drier may be positioned intermediate the two impact flow driers. Alternatively, at least one intermediate impact flow drier may be provided that bombards the material web from opposite web surfaces with hot air or hot steam impact flow, the inte
Chau-Huu Tri
Mayer Roland
Oechsle Markus
Greenblum & Bernstein P.L.C.
Halpern Mark
Silverman Stanley S.
Voith Sulzer Papiertechnik Patent GmbH
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