Systems for tissue dried with metal bands
First Claim
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1. An apparatus for making a foreshortened cellulosic web, in combination with a dryer fabric, the apparatus comprising:
- a) a first press belt having a first press surface, and a second press surface, the second press surface being substantially equidistantly spaced apart from the first press surface in a compression zone;
b) a pressing means for pressing the first and second press surfaces towards each other in the compression zone to compress a cellulosic web residing on the dryer fabric, wherein the first press surface contacts the cellulosic web;
c) a means for creating a temperature differential between the first press surface and the second press surface to move water from the cellulosic web into the dryer fabric;
d) a transporting means for moving the cellulosic web in the machine direction at a first velocity;
e) a foreshortening means for foreshortening the cellulosic web after the web has passed through the compression zone;
f) sensor means for determining the cross-directional variability of a property of at least one of the cellulosic web, the first press belt, the first press surface, and the second press surface, wherein the sensor means generates an output signal based on the cross-directional variability of the property; and
, g) control means for decreasing the cross-directional variability of the property responsive to the signal from the sensor means.
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Abstract
A web treatment device is disclosed capable of heating and creping a fibrous web with control systems for uniform operation. The web is pressed between two belts in a compression zone, where is it also subject to a temperature gradient that can assist in water removal. Durable coatings on the press belts can assist in maintaining good performance. The system can be used to apply texture to a fibrous web or drive chemical reactions or other physical changes in the web.
61 Citations
96 Claims
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1. An apparatus for making a foreshortened cellulosic web, in combination with a dryer fabric, the apparatus comprising:
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a) a first press belt having a first press surface, and a second press surface, the second press surface being substantially equidistantly spaced apart from the first press surface in a compression zone;
b) a pressing means for pressing the first and second press surfaces towards each other in the compression zone to compress a cellulosic web residing on the dryer fabric, wherein the first press surface contacts the cellulosic web;
c) a means for creating a temperature differential between the first press surface and the second press surface to move water from the cellulosic web into the dryer fabric;
d) a transporting means for moving the cellulosic web in the machine direction at a first velocity;
e) a foreshortening means for foreshortening the cellulosic web after the web has passed through the compression zone;
f) sensor means for determining the cross-directional variability of a property of at least one of the cellulosic web, the first press belt, the first press surface, and the second press surface, wherein the sensor means generates an output signal based on the cross-directional variability of the property; and
,g) control means for decreasing the cross-directional variability of the property responsive to the signal from the sensor means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 47, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 59, 60, 61, 62, 63, 64, 85)
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46. A dryer section for a paper machine having a front end, a rear end, a machine direction, a cross direction, and a z-direction substantially normal to both the machine direction and cross-direction, comprising:
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a) an endless dryer fabric;
b) first and second press belts having opposing first and second press surfaces, respectively, through which the dryer fabric passes, adapted such that a web in contact with the dryer fabric and the first press belt can pass between the first and second press belts;
c) a pressing means for driving first and second press surfaces together to pressurize the web;
d) a temperature differential means for maintaining the first press surface at a higher temperature than the second press surface, whereby water removal from the web is enhanced by the resulting temperature differential;
e) a foreshortening means for foreshortening the web after the web is released from the pressure between the first and second press surfaces;
f) a sensor means for determining the cross-directional variability in a property of at least one the first press belt, the second press belt, the web, or a combination thereof, and generating a corresponding signal; and
,g) a control means responsive to the signal of the sensor means for decreasing the cross-directional variability of the property responsive to the sensor means.
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56. A dryer section for drying paper comprising:
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a) a first metallic press belt having a web-contacting surface that passes over a first turning roll;
b) a second metallic press belt passing over a second turning roll, wherein a portion of the second metallic press belt is adjacent to and substantially equidistant to an adjacent a portion of the first metallic press belt to define a compression zone;
c) a vapor permeable dryer fabric passing through the compression zone, adapted for conveying a moist paper web through the compression zone as one side of the paper web is in contact with the first press belt and the opposing side of the paper web is in contact with the dryer fabric;
d) a heating means for heating the first metallic press belt;
e) a pressing means applying mechanical pressure to the paper web in the compression zone; and
,f) a durable coating applied to the web-contacting surface of the first metallic press belt, wherein the coating is at least one of non-metallic and porous.
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65. An apparatus for making a foreshortened cellulosic web, comprising:
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a) an impermeable first press belt having a first press surface, and a unitary second press belt operatively associated with a dryer fabric and having a second press surface and a backside surface opposing the second press surface, the second press surface being provided with pores for receiving condensate;
b) a press means for pressing the first and second press surfaces towards each other in a compression zone to compress a cellulosic web, wherein the first press surface contacts the cellulosic web;
c) a means for creating a temperature differential between the first press surface and the second press surface to move water from the cellulosic web into the dryer fabric;
d) a transporting means for moving the cellulosic web in the machine direction at a first velocity; and
,e) a foreshortening means for foreshortening the cellulosic web after the web has passed through the compression zone. - View Dependent Claims (66, 67, 68, 69, 70, 71, 72, 73, 74, 75)
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76. A method of forming a paper web comprising the steps of:
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a) providing an aqueous dispersion of papermaking fibers;
b) providing a foraminous forming member;
c) providing a first press belt having a surface and a second press belt having a surface;
d) providing a fabric that passes between the first press belt and the second press belt;
e) providing a press means to form an elongated compression zone between the first press belt and the second press belt;
f) providing a temperature differential means to cause the first press belt in the compression zone to be at a substantially higher temperature than the second press belt in the compression zone;
g) providing a foreshortening means for foreshortening a web of papermaking fibers;
h) forming an web of the papermaking fibers on the foraminous forming member, the web having a first face and a second face;
i) transferring the web from the foraminous forming member to contact both the fabric and the surface of the first press belt;
j) pressing the web by the action of the press means in the compression zone as the web resides on the fabric;
k) applying the temperature differential means to vaporize water from the web and cause condensate to form in either the fabric or on the surface of the second press belt; and
,l) removing the web from the first press belt and applying the foreshortening means to the web to foreshorten the web. - View Dependent Claims (77, 78, 79, 80, 81, 82, 83, 84, 86)
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87. An apparatus for drying a paper web comprising:
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a) a first metallic press belt passing over a first turning roll;
b) a second metallic press belt passing over a second turning roll, wherein a portion of the second metallic press belt is adjacent to and substantially equidistant to an adjacent portion of the first metallic press belt to define a compression zone;
c) a vapor permeable dryer fabric passing through the compression zone, adapted for conveying a moist paper web through the compression zone, wherein the paper web is sandwiched between the first metallic press belt and the dryer fabric;
d) a heating means for heating the first metallic press belt;
e) a pressing means applying a first mechanical pressure to the paper web in the compression zone; and
,f) a decompression zone to reduce the pressure applied to the paper web from the first mechanical pressure to ambient pressure over a dwell time of at least 0.02 seconds. - View Dependent Claims (88, 89)
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90. A dryer section for drying a web comprising:
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a) a first metallic press belt passing over a first turning roll;
b) a primary second press belt in opposing relationship to the first metallic press belt, wherein a portion of the second press belt is adjacent to and substantially equidistant to an adjacent portion of the first metallic press belt to define a first compression zone for compressing the web;
c) a secondary second press belt in opposing relationship to the first metallic press belt, defining a second compression zone for compressing the web;
d) a heating means for heating the first metallic press belt;
e) first and second pressing means for applying mechanical pressure to the web in the first and second compression zones, respectively; and
,f) an open zone disposed between the primary and secondary second press belts, wherein a surface of the web is exposed. - View Dependent Claims (91, 92, 93, 94, 95, 96)
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Specification