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Keywords: ON LINE MEASUREMENT, SENSORS, PROCESS CONTROL, QUALITY CONTROL, DRAINAGE, PROFILE CONTROL, MOISTURE CONTROL, MACHINE DIRECTION, CROSS DIRECTION, PAPER MACHINES.
It will increase the likelihood of making better paper
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C. HAGART-ALEXANDER,
Honeywell-Measurex Corp.
Cupertino, CA
(now Honeywell, Inc.)
L. CHASE,
Honeywell-Measurex Corp.
Cupertino, CA
(now Honeywell, Inc.)
B. GARNETT,
Honeywell-Measurex Corp.
Cupertino, CA
(now Honeywell, Inc.)
J. GHOFRANIHA,
Honeywell-Measurex Corp.
Cupertino, CA
(now Honeywell, Inc.)
D. WATSON,
Honeywell-Measurex Corp.
Mississauga, ON
(now Honeywell, Inc.)
THE ADVANCEMENT of technology has opened many new opportunities to further improve the quality of paper to meet the stringent requirements of today's customer. One area that has received more attention is the on-line measurement of paper properties. Scanners have played a major role in maintaining the quality of paper up to now, and will continue to play a very important role for years to come. The emergence of non-scanning gauges for paper measurements, however, is one example of new technology that provides significant new information and potential improvements over conventional measurement solutions.
This article reviews the results obtained from multiple applications of a non-scanning measurement technology installed at the wet end of a paper machine. The new technology measures the weight of the water and fibre on the wire. MD measurement is obtained from a series of sensors mounted in current paper machine drainage foils that are evenly distributed between the headbox and the machine dry-line. This technology has the added advantage of being able to determine the water weight profiles of the individual plies on a multi-ply machine. This approach to the measurement of sheet properties resolves the issue of the transport delay associated with the location of the scanner at the dry end of the paper machine. Besides this benefit, the new technology gives more insight into the papermaking process in areas where it was not possible with standard scanning technology. This aspect of the new measurement system opens the door for new applications in the area of machine monitoring, fault detection and control of non-traditional papermaking processes such as drainage profile control, freeness control and dry-line position monitoring.
In the following sections, a review of possible alternatives, a brief description...