Restrained paper dryer
First Claim
Patent Images
1. An improved method of drying a moving paper web in an elongated drying apparatus comprising the steps of:
- a) holding the web in a restrained position on an open weave fabric by means of air suction from 3 to 12 inches H2 O imposed progressively along the length of the drying apparatus from underneath the web and sufficient to prevent shrinkage of the web; and
b) applying a drying medium to said web in the form of high temperature, high velocity air or superheated steam, whereby shrinkage of said web is substantially inhibited, ring crush strength is increased and fibre requirements are reduced.
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Accused Products
Abstract
Methods and apparatus are disclosed for restrained paper drying in order to produce high performance paper with enhanced stiffness and, in the process, substantially improve paper properties and reduce fiber usage. The paper web is held in a restrained position on a fabric by air suction imposed from beneath the web and is of sufficient application to prevent shrinkage of the web. The web is simultaneously dried by high velocity, high temperature air or superheated steam. For improved finish properties, the wet paper web may be pressed onto a polished heated metal cylinder with restraint being imposed by gluing.
49 Citations
14 Claims
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1. An improved method of drying a moving paper web in an elongated drying apparatus comprising the steps of:
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a) holding the web in a restrained position on an open weave fabric by means of air suction from 3 to 12 inches H2 O imposed progressively along the length of the drying apparatus from underneath the web and sufficient to prevent shrinkage of the web; and b) applying a drying medium to said web in the form of high temperature, high velocity air or superheated steam, whereby shrinkage of said web is substantially inhibited, ring crush strength is increased and fibre requirements are reduced. - View Dependent Claims (2, 3)
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4. Apparatus for drying and moving paper web comprising:
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an elongated module having a plurality of drying nozzles spaced throughout the length of said module; a suction box arranged opposite said module and the drying nozzles therein and defining a path of travel for said paper web between said nozzles and the suction box; means in said suction box for providing support for a fabric, web-supporting belt; means for delivering high velocity, high temperature air or superheated steam to said nozzles for impingement against at least one surface of said web; and means for simultaneously applying suction from 3 to 12 inches H2 O, progressively throughout the length of said suction box, to the other surface of said web sufficient to prevent shrinkage thereof during drying. - View Dependent Claims (5, 6, 7, 8)
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9. An improved method of drying a moving paper web in an elongated multi-pass drying apparatus comprising the steps of:
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a) holding the web in a restrained position on an open weave fabric by means of air suction from 3 to 12 inches H2 O imposed progressively along the length of each pass of the multi-pass drying apparatus from underneath the web and sufficient to prevent shrinkage of the web; and b) applying a drying medium to said web along each pass of the multi-pass apparatus in the form of high temperature, high velocity air or superheated steam, whereby shrinkage of said web is substantially inhibited, ring crush strength is increased and fibre requirements are reduced. - View Dependent Claims (10, 11)
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12. Apparatus for drying a moving paper web comprising:
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a housing enclosing a plurality of jet impingement blow boxes arranged in a stack and each having a plurality of drying nozzles spaced throughout the length of the box; a plurality of suction boxes arranged in the stack intermediate said jet impingement blow boxes;
said blow boxes and suction boxes defining between them a path of travel for said paper web;means in said suction boxes for providing support for a fabric, web-supporting belt; suction turning and guide rolls at each end of said suction boxes for turning and guiding said fabric and web; means for delivering high velocity, high temperature air or superheated steam to said nozzles for impingement against at least one surface of said web on each pass of the apparatus; and means for simultaneously applying suction from 3 to 12 inches H2 O, progressively throughout the length of said suction boxes, to the other surface of said web sufficient to prevent shrinkage thereof during drying. - View Dependent Claims (13, 14)
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Specification