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1. WO2000034575 - PROCEDE ET MATERIEL DE REGULATION DES PROPRIETES DU PAPIER

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

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CLAIMS
1. A method of controlling properties of paper, in which method the effect of at least one variable (fD) of the paper dryer section on the paper moisture (Moi) is modelled, and the moisture (Moi) is controlled by means of said modelling, characterized by modelling the effect of the stock flow (Fts) and/or stock composition and the flow of retention agent (Fra) on the paper moisture (Moi), and adjusting the moisture (Moi) by simultaneously controlling at least one variable (fD) of the paper dryer section, the stock flow (Fts) and the flow of retention agent (Fra).
2. A method according to claim 1, characterized by modelling the effect of the flow of filler (Ffi) on the paper moisture (Moi) and adjusting the paper moisture (Moi) by simultaneously controlling the stock flow (Fts), the flow of retention agent (Fra), the flow of filler (Ffi) and at least one variable (fD) of the paper dryer section.
3. A method according to claim ^characterized by utilizing a dynamic model, which comprises as input variables at least one variable (fD) of the paper dryer section, the stock flow (Fts), the flow of retention agent (Fra) and the speed of the paper machine (S), and the output variables include the paper moisture (Moi) and the basis weight of the paper (BW), and the control variables include at least one variable (fD) of the paper dryer section, the stock flow (Fts) and the flow of retention agent (Fra).
4. A method according to claim 2, characterized by utilizing a dynamic model, which comprises as input variables at least one variable (fD) of the paper dryer section, the stock flow (Fts), the flow of retention agent (Fra), the speed of the paper machine (S) and the flow of filler (Ffi), and the output variables include the paper moisture (Moi) and the basis weight of the paper (BW), and the control variables include the stock flow (Fts), the flow of retention agent (Fra), the flow of filler (Ffi) and at least one variable (fD) of the paper dryer section.
5. A method according to claim 3 or 4, characterized in that the method comprises a predictor and optimization, such that the predictor takes into account situations, operating points and changes in the process and provides a prediction and a new process model on the basis thereof, and the optimization utilizes the process model produced by the predictor.

6. A method according to claim 1, characterized in that the method utilizes a dynamic model, which comprises as input variables at least one variable (fD) of the paper dryer section, the stock flow (Fts), the flow of retention agent (Fra), the speed of the paper machine (S) and the flow of filler (Ffi), and the output variables include the paper moisture (Moi), the basis weight of the paper (BW), the white water consistency (CS^), the headbox ash content (ASHhb) and the paper ash content (ASH), and the control variables include the stock flow (Fts), the flow of retention agent (Fra), the flow of filler (Ffl) and at least one variable (fD) of the paper dryer section, and that the method comprises a predictor and that during a break the basis weight of the paper (BW) is predicted and a set value is given to the headbox ash content (ASHhb) and the paper ash content (ASH) is ignored completely or replaced with a value provided by the model.
7. A method according to any one of the preceding claims, char-acterized by drying the paper in a dryer section (7) comprising at least one impinged blowing unit, at least one variable (fD) of the paper dryer section being a controlled variable of the impinged blowing unit.
8. A method according to claim 7, characterized in that the controlled variable of the impinged blowing unit is the blow rate.
9. A method according to claim 7 or 8, characterized in that the controlled variable of the impinged blowing unit is the blow temperature.
10. A method according to any one of the preceding claims, characterized in that the paper dryer section (7) comprises steam-heated cylinders (10) and at least one impinged blowing unit, slow changes in the paper moisture being adjusted by controlling the variables of the steam-heated cylinders (10), and rapid changes being adjusted by controlling the variables of the impinged blowing unit.
11. A method according to any one of the preceding claims, characterized in that the paper dryer section (7) comprises steam-heated cylinders (10) and at least one impinged blowing unit, and the control of the steam-heated cylinders (10) and the control of the impinged blowing unit are used simultaneously to control the moisture.
12. A method according to claim 10 or 11, characterized by taking into account in the control operation the effect of the different moisture controls on the costs.

13. Equipment for controlling properties of paper, the equipment comprising a model of the effect of at least one variable (fD) of the paper dryer section on the paper moisture (Moi), and control means (13) for adjusting the moisture (Moi) on the basis of said model, characterized in that the model also comprises the effect of the stock flow (Fts) and/or stock composition and the flow of retention agent (Fra) on the paper moisture (Moi), and that the control means (13) comprise means for simultaneously controlling at least one variable (fD) of the paper dryer section, the stock flow (Fts) and the flow of retention agent (Fra) in order to adjust the paper moisture (Moi) on the basis of said model.
14. Equipment according to claim 13, characterized in that the model comprises the effect of the flow of filler (Ffi) on the paper moisture (Moi), and the control means (13) comprise means for simultaneously controlling the stock flow (Fts), the flow of retention agent (Fra), the flow of filler (Ffi) and at least one variable (fD) of the paper dryer section in order to adjust the paper moisture (Moi) on the basis of said model.
15. Equipment according to claim 13, characterized in that the model is a dynamic model, which comprises as input variables the stock flow (Fts), the flow of retention agent (Fra), the speed of the paper machine (S) and at least one variable (fD) of the paper dryer section, and the output variables include the paper moisture (Moi) and the basis weight of the paper (BW), and the control variables include at least one variable (fD) of the paper dryer section, the stock flow (Fts) and the flow of retention agent (Fra).
16. Equipment according to claim 14, characterized in that the model is a dynamic model, which comprises as input variables the stock flow (Fts), the flow of retention agent (Fra), the speed of the paper machine (S), the flow of filler (F^) and at least one variable (fD) of the paper dryer section, and the output variables include the paper moisture (Moi) and the basis weight of the paper (BW), and the control variables include the stock flow (Fts), the flow of retention agent (Fra), the flow of filler (Ffi) and at least one variable (fD) of the paper dryer section.
17. Equipment according to claim 15 or 16, characterized in that the equipment comprises a predictor and optimization, such that the predictor comprises means for taking into account situations, operating points and changes in the process and for providing a prediction and a process model, the optimization comprising means for utilizing the process model produced by the predictor.
18. Equipment according to any one of claims 13 to 17, characterized in that the paper dryer section (7) comprises at least one impinged blowing unit, at least one variable (fD) of the paper dryer section being a controlled variable of the impinged blowing unit.
19. Equipment according to claim 18, characterized in that the equipment comprises means for controlling the blow rate of the impinged blowing unit.
20. Equipment according to claim 18 or 19, characterized in that the equipment comprises means for controlling the blow temperature of the impinged blowing unit.
21. Equipment according to any one of claims 13 to 20, characterized in that the paper dryer section (7) comprises steam-heated cylinders (10) and at least one impinged blowing unit, and the control means (13) are arranged in slow changes to control the properties of the steam-heated cylinders (10), and in rapid changes to control the properties of at least one impinged blowing unit.