# US 7,407,562 B2 · Method, system and calendar for controlling the moisture profile and/or moisture gradient of a paper web, and a web

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- Number: US 7,407,562 B2
- Document ID: US7407562B2
- Status: Granted
- Kind: B2
- Application number: 10/518,416
- Filed: 2003-06-16
- Published: 2006-06-08
- Granted: 2008-08-05
- Earliest claimed: 2002-06-19
- Assignees: Metso Paper, Inc.
- Inventors: Antti Heikkinen; Harri Kuosa; Pekka Linnonmaa; Hannu Lätti; Markku Kyytsönen; Markko Jaakkola
- Web page: https://patentgrep.com/patent/US7407562B2

## CPC

- D21G 1/00: Calenders (if restricted to the treatment of particular materials see the relevant class, e.g. B29C43/24, D06); Smoothing apparatus
- D21G 1/0093: {Web conditioning devices}
- D21G: CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES (winders or rewinders for finished products, means for adjustment of wrinkles or lateral extensions B65H)

## Abstract

The moisture profile and/or moisture gradient of a paper web of at least SC quality paper is controlled in a paper machine comprising a calender (1) which has at least two roll stacks (21, 22; 31, 32), one stack has at least three rolls and another has at least five rolls. The web is moisturized to a desired pre-moisture content M1 by a pre-moisturizer (7) before the calender. At least one intermediate moisturizer (3) is arranged between two roll stacks moisturizes the web to a desired intermediate moisture content M2 before the last roll stack (31, 32), in which the web is dried to a desired final moisture value M3. For continuously controlling and optimizing the moisture profile and/or moisture gradient of the web, the pre-moisturizing W1 of the web is controlled by a pre-moisturizer (7) control parameter which corresponds to the final moisture value M3 of the web.

## Claims

### Claim 1

A method for controlling the moisture gradient in production of an uncoated paper web of at least SC quality, having a cross direction, a running direction and a thickness direction, comprising the steps of:
pre-moisturizing, with a pre-moisturizer, the paper web in the cross direction substantially across the entire width of the web from an initial moisture content before pre-moisturizing to a selected pre-moisture content;
passing the pre-moisturized paper web through a multi-nip calender having at least a first roll stack and a last roll stack, each roll stack having at least three rolls, and wherein the multi-nip calender is situated before a slitter-winder of the web;
intermediate-moisturizing the web, with an intermediate-moisturizer, in the cross direction substantially across the entire width of the web before the last roll stack and after a first calendering nip of the first roll stack to a selected intermediate moisture content;
drying the web in the last roll stack to a selected final moisture value;
continuously controlling the moisture gradient of the web in the thickness-direction in the multi-nip calender by adjusting the pre-moisturizing of the web, based on a calculated or measured value of the selected final moisture value of the web.

### Claim 2 (depends on 1)

The method of claim 1, wherein the pre-moisturizer is controlled by the final moisture value of the web as measured after the last roll stack.

### Claim 3 (depends on 1)

The method of claim 1 wherein the intermediate moisturizer is controlled by the final moisture value of the web as measured after the last roll stack.

### Claim 4 (depends on 1)

The method of claim 1 wherein the pre-moisturizer or the intermediate moisturizer is controlled automatically.

### Claim 5 (depends on 1)

The method of claim 1 wherein a final moisture value is calculated from the selected pre-moisture value of the web and from evaporation of moisture that has occurred in each roll stack; and the intermediate moisturizing of the web is carried out by the intermediate moisturizer of the web.

### Claim 6 (depends on 1)

The method of claim 1 wherein evaporations from each roll and the additional or intermediate moisturizing of the web form a subtotal, and that said subtotal and the pre-moisture value of the web are passed as separate variables through a coupling means to serve as a control parameter of the pre-moisturizer.

### Claim 7 (depends on 1)

The method of claim 1 wherein the final moisture value which has been either measured, or calculated in a coupling means, is passed by means of the coupling means to serve as a control parameter of the pre-moisturizer.