Method for contact drying a paper web and a dryer section of a paper machine
First Claim
1. A method for contact drying a paper web in a dryer section including a plurality of successively arranged normal groups with single-wire draw, each of said normal groups including heated smooth-faced drying cylinders situated in a row, reversing suction cylinders or reversing suction rolls situated in another row spaced from said row of drying cylinders, and a drying wire for pressing the paper web into contact with said drying cylinders and for carrying the paper web between said drying cylinders and said reversing suction cylinders or rolls, the method comprising the steps of:
- drying the paper web to substantially a first dry solids content by passing the web through said plurality of successively arranged normal groups with single-wire draw, and thereafterdrying the paper web to substantially a second dry solids content by passing the web through a hybrid group including a single-wire draw portion and a twin-wire draw portion, said single-wire draw portion including heated smooth-faced drying cylinders situated in a first row, reversing suction cylinders or rolls situated in a second row spaced from said first row, and a drying wire for pressing the paper web into contact with said drying cylinders and for carrying the paper web between said drying cylinders and said reversing suction cylinders or rolls, said twin-wire draw portion including drying cylinders arranged in said first row and a second row, wire guide rolls arranged between adjacent ones of said drying cylinders in each of said first and second rows, and first and second drying wires for pressing the web against the surfaces of said drying cylinders in a respective row,said first drying wire of said twin-wire draw portion constituting the drying wire in said single-wire draw portion.
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Accused Products
Abstract
A method for contact drying a paper web, wherein the paper web is dried by heated smooth-faced drying cylinders by passing the web through successively arranged so-called normal groups with single-wire draw in which drying cylinders are situated in a first row and reversing suction cylinders or equivalent suction rolls are situated in a second row. Thereafter, the web is dried by passing it through a hybrid dryer group which hybrid dryer group consists of a normal portion with single-wire draw and a portion with twin-wire draw, one of the wires in the twin-wire portion constituting the wire of the portion with single-wire draw whereas the other wire in the twin-wire portion is a separate wire. The invention also relates to a dryer section of a paper machine wherein the initial part includes successively arranged so-called normal groups with single-wire draw after which one hybrid dryer group is provided, in which there is a portion with single-wire draw and a portion with twin-wire draw. In the hybrid group, one row includes drying cylinders over which the wire of the single-wire draw runs, and the other row includes reversing cylinders, suction rolls or equivalent, and drying cylinders. A separate wire runs over the drying cylinders in this row.
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Citations
27 Claims
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1. A method for contact drying a paper web in a dryer section including a plurality of successively arranged normal groups with single-wire draw, each of said normal groups including heated smooth-faced drying cylinders situated in a row, reversing suction cylinders or reversing suction rolls situated in another row spaced from said row of drying cylinders, and a drying wire for pressing the paper web into contact with said drying cylinders and for carrying the paper web between said drying cylinders and said reversing suction cylinders or rolls, the method comprising the steps of:
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drying the paper web to substantially a first dry solids content by passing the web through said plurality of successively arranged normal groups with single-wire draw, and thereafter drying the paper web to substantially a second dry solids content by passing the web through a hybrid group including a single-wire draw portion and a twin-wire draw portion, said single-wire draw portion including heated smooth-faced drying cylinders situated in a first row, reversing suction cylinders or rolls situated in a second row spaced from said first row, and a drying wire for pressing the paper web into contact with said drying cylinders and for carrying the paper web between said drying cylinders and said reversing suction cylinders or rolls, said twin-wire draw portion including drying cylinders arranged in said first row and a second row, wire guide rolls arranged between adjacent ones of said drying cylinders in each of said first and second rows, and first and second drying wires for pressing the web against the surfaces of said drying cylinders in a respective row, said first drying wire of said twin-wire draw portion constituting the drying wire in said single-wire draw portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A dryer section of a paper machine for drying a paper web, comprising
a plurality of successively arranged normal groups with single-wire draw, each of said normal groups including drying cylinders arranged in one row, reversing rolls arranged in another row spaced from said row of said drying cylinders, and a drying wire for carrying the web between said drying cylinders and said reversing rolls, and a hybrid dryer group arranged after said plurality of normal groups in a running direction of the web, said hybrid dryer group comprising a single-wire draw portion including heated smooth-faced drying cylinders situated in a first row, reversing rolls, and a first drying wire for pressing the web into contact with said drying cylinders and carrying the web between said drying cylinders and said reversing rolls, and a twin-wire draw portion including drying cylinders arranged in said first row and a second row, wire guide rolls arranged between adjacent ones of said drying cylinders in each of said first and second rows, and a second drying wire for pressing the web against said drying cylinders in said second row, said first drying wire also forming a part of said twin-wire draw portion and pressing the web against said drying cylinders in said first row of said twin-wire draw portion.
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27. A hybrid dryer group in a dryer section of a paper machine in which a paper web is dried, comprising
a single-wire draw portion including heated smooth-faced drying cylinders situated in a first row, reversing suction rolls, and a first drying wire for pressing the web into contact with said drying cylinders and carrying the web between said drying cylinders and said reversing rolls, said suction rolls being structured and arranged to apply negative pressure to the web through said drying wire to draw water from the web into said suction rolls, a twin-wire draw portion including drying cylinders arranged in said first row and a second row, wire guide rolls arranged between adjacent ones of said drying cylinders in each of said first and second rows, and a second drying wire for pressing the web against said drying cylinders in said second row, said first drying wire also forming a part of said twin-wire draw portion and pressing the web against said drying cylinders in said first row of said twin-wire draw portion.
Specification