Paper making and fiber liberation – Processes and products – With measuring – inspecting and/or testing
Reexamination Certificate
1997-12-31
2001-02-13
Fiorilla, Christopher A. (Department: 1731)
Paper making and fiber liberation
Processes and products
With measuring, inspecting and/or testing
C162S252000
Reexamination Certificate
active
06187145
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method and a device for the process management of a paper machine for the production of paper and/or board, using at least one measuring device for registering physical characteristic values and at least one regulating or controlling device for the operating means used in the paper machine.
BACKGROUND OF THE INVENTION
In the earlier international Patent Application WO 95/08019 A1, which is not a prior publication, a device is proposed for operating an installation specifically for the production of deinked pulp. The installation includes at least one waste paper preparation means, downstream of which a paper machine or at least one dewatering machine is connected. In this case, measuring devices for registering spectral and/or physical characteristic values of the waste paper suspension are already used. Furthermore, regulating or controlling devices are used there for the operating means of the waste paper preparation means. There is also at least one state analyser, designed in the form of one or more parallel neural networks, for the waste paper suspension. The analyzer, by means of the characteristic values of the measuring device, supplies controlled variables for process management to the regulating or controlling devices of the operating means for the waste paper preparation means.
In the case of the device described above for the production of deinked pulp, using as great a proportion as possible of waste paper, there is in particular the problem that the quality of waste paper introduced into the installation fluctuates severely. For example, there can be, in the respective mixture of waste paper, sharply variable proportions of, for example, coloured illustrated paper, gray newsprint, white paper, contaminated paper, old books, for example with adhesive residues, such as telephone directories, cartons, packages, coated papers and contaminations of all types. The device previously described in the earlier Patent Application solves these problems in a satisfactory manner for the waste paper preparation means.
EP-A-0,137,696 discloses a method and an associated device for registering the water content of a paper web during production, in which, via an optical infrared measurement, use is made of the fact that water has an absorption band at 1.94 &mgr;m. To this end, a measuring channel and a reference channel having a different wavelength than the water absorption band is used. In addition, U.S. Pat. No. 5,282,131 discloses a system for regulating a pulp washing plant, in which a neuron network is employed to verify predictable process parameters. In the case of both of these documents, therefore, only some aspects of paper production are addressed.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the present invention is to use the measurement principle on which the above described device is based directly in a paper machine. The object is achieved, according to the invention, in that, using the measuring device, spectral characteristic values are registered at different wavelengths on the operating materials of the paper machine. The operating materials are the starting material directly before the flow box on the paper machine and/or the intermediate or final product. The signals from the measuring device for the spectral characteristic values are evaluated by at least one neural network and statements about the product quality are derived therefrom. The statements are, in particular, the quality parameters of the paper or of the board. Signal variables are derived from the statements about the product quality. The signal variables may be used, on the one hand, for feedback control in the so-called stock preparation upstream of the paper machine, and on the other hand, for the feed forward control of the paper machine itself.
In the case of feedback control, the parameters of the stock preparation are adjusted to produce the stock quality necessary for an intended paper or board quality. In the case of feedforward control, on the other hand, the operating means of the paper machine are controlled so that an intended paper or board quality is achieved with a given stock quality.
The result of the invention is to provide, for the first time, the possibility of an on-line measurement using the spectrometer in a paper machine. By suitable evaluation, with determination of the quality values of the paper or the board, the quality-influencing parameters in the stock preparation for the paper machine can also be influenced. The delay times which were produced with the previously normal laboratory measurement are thus dispensed with.
In the associated arrangement, spectroscopes or spectrometers are used, in particular for picking up spectral distributions or overall spectra. The neural networks are used within the context of the invention, specifically for the evaluation of spectral characteristic values. Either the diffuse backscatter intensity or the diffuse transmitted intensity of selected spectral ranges is used as input variables for the neural networks. Further parameters of the stock suspension or of the paper or board, for example, consistency, moisture, grammage and the like, may also advantageously be used as input variables for the neural networks. Output variables from the neural networks are mechanical quality parameters of the paper or board produced, such as in particular, the so-called CMT value, the breaking length, the burst pressure, and other factors which are significant for the practical suitability of the paper. The neural networks can be trained using quality parameters measured off-line in the laboratory.
REFERENCES:
patent: 4098641 (1978-07-01), Casey et al.
patent: 5082529 (1992-01-01), Burk
patent: 5220172 (1993-06-01), Berthold et al.
patent: 5282131 (1994-01-01), Rudd et al.
patent: 5486996 (1996-01-01), Samad et al.
patent: 5841671 (1998-11-01), Furumoto
patent: 0 137 696 (1985-04-01), None
patent: 95/08019 (1995-03-01), None
Furumoto Herbert
Gerdemann Ulrich
Zeiner Gerhard
Fiorilla Christopher A.
Kenyon & Kenyon
Siemens Aktiengesellschaft
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