Claims
- 1. A method of controlling properties of paper in a paper machine and process, the method comprising:
modeling the effects on paper moisture of a stock flow supplied to a former of the machine, a flow of retention agent, and at least one variable of a dryer section of the machine; and adjusting the paper moisture by simultaneously controlling the stock flow, the flow of retention agent, and the at least one variable of the dryer section.
- 2. The method according to claim 1, further comprising modeling the effect of a flow of filler on the paper moisture, and wherein the paper moisture is adjusted by simultaneously controlling the stock flow, the flow of retention agent, the flow of filler, and the at least one variable of the dryer section.
- 3. The method according to claim 1, wherein a dynamic model is utilized, which comprises input, output, and control variables, the input variables including the at least one variable of the dryer section, the stock flow, the flow of retention agent, and speed of the paper machine, the output variables including basis weight of the paper and the paper moisture, and the control variables including the at least one variable of the dryer section, the property of the stock, and the flow of retention agent.
- 4. The method according to claim 2, wherein a dynamic model is utilized, which comprises input, output, and control variables, the input variables including the at least one variable of the dryer section, the stock flow, the flow of retention agent, speed of the paper machine, and the flow of filler, the output variables including basis weight of the paper and the paper moisture, and the control variables including the stock flow, the flow of retention agent, the flow of filler, and the at least one variable of the dryer section.
- 5. The method according to claim 1, wherein the method comprises using 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. The method according to claim 1, wherein the method utilizes a dynamic model, which comprises input, output, and control variables, the input variables including the at least one variable of the dryer section, the stock flow, the flow of retention agent, speed of the paper machine, and a flow of filler, the output variables including the paper moisture, basis weight of the paper, a white water consistency, a headbox ash content, and a paper ash content, and the control variables including the stock flow, the flow of retention agent, the flow of filler, and the at least one variable of the dryer section, and wherein during a break a predictor is used to predict the basis weight of the paper and a set value is given to the headbox ash content and the paper ash content is ignored completely or replaced with a value provided by the model.
- 7. The method according to claim 1, wherein the paper is dried in a dryer section comprising at least one impinged blowing unit, the at least one variable of the paper dryer section being a controlled variable of the impinged blowing unit.
- 8. The method according to claim 7, wherein the controlled variable of the impinged blowing unit is a blow rate.
- 9. The method according to claim 7, wherein the controlled variable of the impinged blowing unit is a blow temperature.
- 10. The method according to claim 1, wherein the dryer section comprises steam-heated cylinders and at least one impinged blowing unit, slow changes in the paper moisture being adjusted by controlling variables of the steam-heated cylinders, and rapid changes being adjusted by controlling at least one variable of the impinged blowing unit.
- 11. The method according to claim 1, wherein the dryer section comprises steam-heated cylinders and at least one impinged blowing unit, and control of the steam-heated cylinders and control of the impinged blowing unit are used simultaneously to control the paper moisture.
- 12. The method according to claim 1, wherein the dryer section comprises steam-heated cylinders and at least one impinged blowing unit, and control of the steam-heated cylinders and control of the impinged blowing unit are both used to control the paper moisture, and wherein control of the paper moisture takes into account a cost of controlling the paper moisture via control of the impinged blowing unit and a cost of controlling the paper moisture via control of the steam-heated cylinders.
- 13. Equipment for controlling properties of paper in a paper machine and process, the equipment comprising:
a model operable to determine effects on paper moisture of at least one variable of a dryer section of the machine, a stock flow supplied in a former of the machine, and a flow of retention agent; and a controller operable to simultaneously control the at least one variable of the dryer section, the stock flow, and the flow of retention agent so as to adjust the paper moisture based on said model.
- 14. Equipment according to claim 13, wherein the model is operable to determine the effect of a flow of filler on the paper moisture, and the controller is operable to simultaneously control the stock flow, the flow of retention agent, the flow of filler, and the at least one variable of the dryer section so as to adjust the paper moisture based on said model.
- 15. Equipment according to claim 13, wherein the model is a dynamic model, which comprises input, output, and control variables, the input variables including the stock flow, the flow of retention agent, speed of the paper machine, and the at least one variable of the dryer section, the output variables including the paper moisture and a basis weight of the paper, and the control variables including the at least one variable of the dryer section, the stock flow, and the flow of retention agent.
- 16. Equipment according to claim 14, wherein the model is a dynamic model, which comprises input, output, and control variables, the input variables including the stock flow, the flow of retention agent, speed of the paper machine, the flow of filler, and the at least one variable of the dryer section, the output variables including the paper moisture and a basis weight of the paper, and the control variables including the stock flow, the flow of retention agent, the flow of filler, and the at least one variable of the dryer section.
- 17. Equipment according to claim 13, wherein the equipment comprises a predictor and optimization, the predictor being operable to take into account situations, operating points, and changes in the process and to provide a prediction and a process model, the optimization utilizing the process model produced by the predictor.
- 18. Equipment according to claim 13, wherein the dryer section comprises at least one impinged blowing unit, the at least one variable of the dryer section being a controlled variable of the impinged blowing unit.
- 19. Equipment according to claim 18, wherein the equipment comprises means for controlling a blow rate of the impinged blowing unit.
- 20. Equipment according to claim 18, wherein the equipment comprises means for controlling a blow temperature of the impinged blowing unit.
- 21. Equipment according to claim 13, wherein the dryer section comprises steam-heated cylinders and at least one impinged blowing unit, and the controller is operable to produce slow changes by controlling properties of the steam-heated cylinders, and to produce rapid changes by controlling properties of the at least one impinged blowing unit.
Priority Claims (1)
Number |
Date |
Country |
Kind |
982625 |
Dec 1998 |
FI |
|
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation of International Patent Application PCT/FI99/00997, filed Dec. 2, 1999, which claims priority from Finnish Patent Application No. 982625 filed Dec. 4, 1998.
Continuations (1)
|
Number |
Date |
Country |
Parent |
PCT/FI99/00997 |
Dec 1999 |
US |
Child |
09864739 |
May 2001 |
US |