Process and apparatus for monitoring dewatering in a wet section of a paper machine

Abstract

Process and apparatus for monitoring dewatering in a wet end section of a web production machine. The process includes measuring water flowing into the wet end section, measuring water flowing out of the wet end section, detecting conductivity, in which the conductivity versus dissolved solids is linear, of the wet web entering the wet end section, measuring conductivity of the water flowing into wet end section, measuring conductivity of water flowing out of the wet end section, and determining a water balance from the measured quantities, which is indicative of dewatering in the wet end. The apparatus is arranged to perform the process. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a Continuation of U.S. patent application Ser. No. 10 / 050,167 filed Jan. 18, 2002, the disclosure of which is expressly incorporated by reference herein in its entirety.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention is directed to a process and apparatus for monitoring dewatering in a wet end section of a paper machine, in particular in the press section. [0004] 2. Discussion of Background Information [0005] In the wet end section of a paper machine, e.g., in the press section, the wet fiber web is pressed between cylindrical rolls. Press fabrics are passed through press nips formed by these cylindrical rolls with the web to cushion the web and to absorb water squeezed from the web. A series of press nips acts upon the web before it leaves the press section to pass to the dryer section of the paper machine. [0006] The water removed from the paper web is partly absorbe...

AI Technical Summary

Benefits of technology

The invention provides a process and apparatus for monitoring the dewatering process in a paper machine during operation. The invention can determine the solid content of the paper web leaving the press section and the cross-direction profile of the water removal. This information can be used to determine the water balance of the press section and the fate of the water in the press section. The invention utilizes the cross-direction water removal profile to condition the felt and determine when replacement of the felt is necessary. The invention can also measure the conductivity of the water in the press section and use it to determine the origin and fate of all water in the press section. Overall, the invention provides a way to monitor and improve the dewatering process in a paper machine.

Problems solved by technology

At present it is not possible to know the dryness of the paper web as it leaves each press nip or as it finally enters the dryer section.

To measure the water content directly requires that the sheet be broken, and the machine be out of use for a costly period of downtime.

Because the carrying out of these material balance procedures require expertise and time, they are not normally carried out except under special circumstances.

Consequently, during the normal running of the paper machine there are many unknowns which prevent optimization of the water removal process.

However, none of these measurement methods meet the requirements for continuous material balance monitoring during paper machine operation.

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