Drying and gas or vapor contact with solids – Process – Gas or vapor contact with treated material
Patent
1996-04-04
1998-02-17
Bennett, Hanry A.
Drying and gas or vapor contact with solids
Process
Gas or vapor contact with treated material
34454, 34117, 34568, D21F 500
Patent
active
057180601
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of simulating a steady state moisture content of a web product on a paper machine in which a web (a moist web) along with a canvas belt are passed around the steam-heated drums of a drying section to dry the web, and an apparatus for carrying out the above-mentioned method. More specifically, the present invention relates to a method of simulating the effect of varying the pressure of steam supplied to steam-heated drums of a paper machine on the moisture content of a web product during an unsteady transferring state in the paper producing process in which a moist web and a canvas belt are fed around steam-heated drums in the paper machine to obtain the dried web product, and an apparatus for carrying out the method.
The present invention also relates to a method of controlling the moisture content of a web so that the moisture content of the web is adjusted to a desired moisture content when a grade of a web product on a paper machine, in which a moist web along with a canvas belt are passed around steam-heated drums thereof to dry the web, should be changed from one web product grade to a different web product grade, and a control apparatus for carrying out such method.
BACKGROUND ART
As is generally known, a typical paper machine has a wire section, a press section, a predrying section, a sizing section, and an afterdrying section. The wire section includes an endless wire belt, and a stock inlet unit is disposed at the receiving end of the wire section. Paper stock, i.e., pulp, is discharged from the stock inlet unit into the wire section. Water contained in the paper stock is drained in the wire section to form a web. The web is delivered from the wire section to the press section and the web is further drained of water in the press section, and then the web is delivered, as a moist web, to the predrying section. A plurality of steam-heated drums are arranged in the predrying section and are heated by steam supplied thereto. The moist web is wound sequentially around the steam-heated drums of the predrying section and is dried by the steam-heated drums to a predetermined moisture content. Subsequently, the web is subjected to a sizing process in the sizing section, and then the sized web is further dried to have a predetermined moisture content while the sized web passes through the afterdrying section. The construction and arrangement of the afterdrying section are substantially the same as that of the predrying section. After being thus dried in the afterdrying section, the web is taken up in a roll as a final product.
The basis weight and the moisture content of the web must be measured at the outlet of the afterdrying section and the paper stock discharge rate at which the paper stock is discharged into the wire section and the steam pressures in the steam-heated drums must be controlled on the basis of measured data. Such control operations are carried out by a basis weight and moisture measuring system (hereinafter referred to as "BM measuring system"). The BM measuring system is provided with measuring units disposed just behind the predrying section and the afterdrying section, respectively, and a control unit for processing data provided by the respective measuring units. In short, paper stock discharge rate at which the paper stock is discharged into the wire section, the pressure of the steam supplied to the steam-heated drums and such are controlled on the basis Of the data provided by the measuring units, i.e., the basis weight and the moisture content of the web, the web speed of the paper machine, and such, to produce a web having uniform quality.
A paper-making process condition control function to control a change in the grade of a web product from one to a different grade is one of the control functions of the BM measuring system. Namely, according to the paper-making process condition control function, the control unit changes, while the paper machine is operating continuously, paper-making process conditions, including p
REFERENCES:
patent: 2197823 (1940-04-01), Young
patent: 3363325 (1968-01-01), Schie
patent: 3625812 (1971-12-01), Gudaz
patent: 5262955 (1993-11-01), Lewis
patent: 5298122 (1994-03-01), Munch et al.
patent: 5377428 (1995-01-01), Clark
patent: 5379528 (1995-01-01), Oeschle
patent: 5563809 (1996-10-01), Williams et al.
John A. Depoy, "Analog Computer Simulation of Paper Drying a Workable Model", Pulp and Paper of Canada, vol. 73, No. 5, pp. 67-74, May 1972.
Hinds, et al., "The Dynamic Computer Simulation of Paper Machine Dryer", Tappi Journal, vol. 66, No. 6, pp. 79-82, (Jun. 1983).
Nissan, et al., "Heat Transfer and Water Removal in Cylinder Drying", Tappi Journal, vol. 43, No. 9, pp. 753-756, (Sep. 1960).
Nissan, et al., "Heat Transfer and Water Removal in Cylinder Drying", Tappi Journal, vol. 45, No. 3, pp. 213-218, (Mar. 1962).
Bennett Hanry A.
Gravini Steve
New Oji Paper Co. Ltd.
LandOfFree
Method of and apparatus for controlling moisture content of a we does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of and apparatus for controlling moisture content of a we, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of and apparatus for controlling moisture content of a we will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1775370