Sheet Properties Predictions: A Mill’s Experience Selling by the Model., 2004 Paper Summit, Spring Technical & International Environmental Conference, (including Papermakers; Process Control, Electrical & Information; Product & Product Quality)

A “virtual sensor” for paper strength properties has been developed and put into service on two paper machines. These “virtual sensors” have replaced the typical laboratory testing with continuous measurements that are used by the machine operator to optimize production and quality. The development and implementation of these “sensors” is presented in detail in this paper.

This effort was undertaken because of the challenge faced by the machine crew. Scanning systems measure several key properties on-line, such as basis weight, moisture, caliper, smoothness, etc. However, there are still many physical tests that are currently measured after a reel turn-up with manual samples in a production laboratory. The lab result is returned as much as fifteen minutes or more after the turn-up event, introducing a delay in action.

Furthermore, many lab tests are inherently noisy. If the test result comes back and is bad, does the operator take immediate action? He probably doesn’t. Often he waits until the next test to determine if a bad test result has occurred, or the lab may repeat the first test to verify that it is out of specification. This again delays action. In the meantime, a significant amount of production is either sold at a greatly reduced rate, or if the situation is bad enough, the reel is cut down and repulped.

Thus, there is the opportunity to improve machine efficiency by getting the tests data to the operator quickly. This paper discusses this type of system and the 1 ½ years of operating experience at the mill; “Selling by the Model.”