Method and control device for paper web profile control with plurality of sensors

• US 6,179,964 B1
• Filed: 09/02/1997
• Issued: 01/30/2001
• Est. Priority Date: 08/30/1996
• Status: Expired due to Fees

• Current Assignee: Voith Sulzer Papiermaschinen GmbH
• Original Assignee: Voith Sulzer Papiermaschinen GmbH
• Inventors: Münch, Rudolf, Begemann, Ulrich
• Primary Examiner(s): Chin, Peter
• Assistant Examiner(s): Halpern, Mark
• Application Number:
  US08/922,995
• Time in Patent Office: 1,246 Days
• Field of Search: 162/198, 162/252, 162/253, 162/263, 162/259, 162/DIG.10, 364/471.01, 364/471.03
• US Class Current: 162/198
• CPC Class Codes: D21G 9/0009 Paper-making control systems
• CPC Class Codes: Y10S 162/10 Computer control of paper making variables

Abstract

The invention relates to a closed-loop control device and a method for the control of the cross-machine and/or machine direction profile of at least one quality feature in the paper manufacturing process with the aid of two sensors. The first sensor picks up a first measured signal of the cross-machine and/or machine direction profile of a first quality feature of the paper web produced. A second sensor picks up a further measured signal. The further sensor is suitable for picking up a quality feature that differs from that picked up by the first sensor, or measures the first quality feature. One or both sensors traverse the web separately. The sensors act through a controller on actuators leading to the feed line or lines for the suspension leading to the flowbox of the machine for controlling thereby the first quality feature of the process.

Claims

1. A paper quality control device for controlling at least one of the cross-machine direction profile and the machine direction profile of at least one quality feature of a paper web as it is being produced in a paper making machine, the paper quality control device comprising:

a controller for receiving signals from a sensor and for driving and controlling an actuator;

least one actuator which is connected with the controller and is operable by the controller for influencing at least one of the cross-machine direction profile and the machine direction profile of the at least one quality feature of the web;

at least a first sensor adapted to and positioned for picking up a first measured signal of at least one of a first cross-machine direction profile and a first machine direction profile of a first quality feature of the paper web, the first sensor being connected with the controller for supplying a first signal to the controller;

at least a second sensor spaced from the first sensor in the machine direction adapted for picking up a second measured signal of a second cross-machine direction profile and a second machine direction profile of a second quality feature of the web, the second sensor being connected with the controller for supplying a second signal to the controller;

the controller receiving signals from the first and second sensors and being adapted to drive the actuator to adjust or control at least one of the cross-machine direction and machine direction profiles of the one quality feature of the web.

2. The control device of claim 1, wherein the first and second sensors differ such that the second measured signal picked up by the second sensor differs from the first measured signal picked up by the first sensor.

3. The control device of claim 2, wherein the first and second sensors move along the cross-machine direction.

4. The control device of claim 3, wherein the first and second sensors include means enabling moving in opposite directions at least part of the time.

5. The control device of claim 2, wherein at least one of the sensors moves along the cross-machine direction.

6. The control device of claim 2, wherein the first sensor moves along the cross-machine direction and the second sensor is in a fixed position with reference to the movement of the paper web past the second sensor and with reference to the moving by the first sensor.

7. The control device of claim 2, wherein the controller is operable for splitting the first and second measured signals into a machine direction signal component and a cross machine direction signal component.

8. The control device of claim 7, wherein the controller comprises:

a machine direction controller part to which the machine direction signal component is fed;

a cross machine direction controller part to which the cross machine direction signal component is fed;

the actuator includes a machine direction component actuator connected with the machine direction controller part; and

the actuator further includes a cross machine direction component actuator connected with the cross-machine direction controller part.

9. The control device of claim 1, being located on a paper making machine having a wet end;

and

the second sensor is arranged toward the wet end of the paper making machine to measure the respective one of the cross machine direction profile and the machine direction profile of the quality feature and to measure it at the wet end of the machine.

10. The control device of claim 1, further comprising a feed device including at least one feed line delivering pulp suspension to the machine and a paper making machine flowbox which receives the suspension from the at least one feed line;

the second sensor is arranged in at least one of the feed lines to the flowbox.

11. The control device of claim 1, further comprising a feed device including at least one feed line delivering pulp suspension to the machine and a paper making machine flowbox which receives the suspension from the at least one feed line;

the flowbox having a common feed line leading to the feed lines to the flowbox; and

the second sensor being in the common feed line.

12. The control device of claim 1, wherein the at least one quality feature is selected from the group consisting of the paper formation, the ash content, the paper thickness, the moisture of the paper web at the sensor, the opacity of the paper web at the sensor, the roughness of the paper web at the sensor, the mechanical sheet properties of the paper web at the sensor, the grammage profile of the paper web at the sensor, and the fiber orientation of the web at the sensor.

13. The control device of claim 1, wherein the at least one quality feature is selected from the group consisting of the grammage profile of the paper web and the fiber orientation of the paper web;

and

the second sensor is selected from the group consisting of a paper stock consistency sensor, a grammage sensor, a layer thickness sensor, and a mass flow per unit area sensor.

14. A paper quality control device for controlling at least one of the cross-machine direction profile and the machine direction profile of at least one quality feature of a paper web as it is being produced in a paper making machine, the paper quality control device comprising:

a controller for receiving signals from a sensor and for driving and controlling an actuator;

at least one actuator which is connected with the controller and is operable by the controller for influencing at least one of the cross-machine direction profile and the machine direction profile of the at least one quality feature of the web;

at least a first sensor for picking up a first measured signal of at least one of a first cross machine direction profile and a first machine direction profile of the quality feature of the paper web being produced and for supplying the first signal to the controller;

at least a second sensor spaced in the machine direction from the first sensor for picking up a second measured signal of at least one of a second cross-machine direction profile a second machine direction profile related to one of the quality features of the web and for supplying the second signal to the controller;

at least one of the first and second sensors moves along the cross-machine direction;

the controller receiving signals from the first and second sensors and being adapted to drive the actuator to adjust or control at least one of the cross-machine direction and machine direction profiles of the one quality feature of the web.

15. The control device of claim 14, wherein both of the first and second sensors move along the cross-machine direction.

16. The control device of claim 15, wherein the first and second sensors include means enabling them to move in opposite directions at least part of the time.

17. The control device of claim 14, wherein the controller is operable for splitting the first and second measured signals into a machine direction signal component and a cross-machine direction signal component.

18. The control device of claim 17, further comprising:

a machine direction controller part to which the machine direction signal component is fed;

a cross machine direction controller part to which the cross machine direction signal component is fed;

the actuator includes a machine direction component actuator connected with the machine direction controller part; and

the actuator further includes a cross machine direction component actuator connected with the cross-machine direction controller part.

19. The control device of claim 18, wherein the cross machine direction component actuator comprises a controlled consistency flowbox for suspension.

20. The control device of claim 19, further comprising dilution feed lines into the flowbox for feeding paper stock suspension;

and

the controlled consistency flowbox comprises a control valve in each dilution means feed line for the paper stock suspension.

21. The control device of claim 14, wherein the device is located on a paper making machine having a wet end;

and

the second sensor is arranged toward the wet end of the paper making machine to measure the respective one of the cross machine direction profile and the machine direction profile of the quality feature at the wet end of the machine.

22. The control device of claim 14, further comprising a feed device including at least one feed line delivering pulp suspension to the machine;

a paper making machine flowbox which receives the suspension from the at least one feed line; and

the second sensor is arranged in at least one of the feed lines to the flowbox.

23. The control device of claim 14, wherein the quality feature is selected from the group consisting of the paper formation, the ash content, the paper thickness, the moisture of the paper web at the sensor, the opacity of the paper web at the sensor, the roughness of the paper web at the sensor, the mechanical sheet properties of the paper web at the sensor, the grammage profile of the paper web at the sensor, and the fiber orientation of the web at the sensor.

24. The control device of claim 14, wherein the quality feature is selected from the group consisting of the grammage profile of the paper web and the fiber orientation of the paper web;

and

the second sensor is selected from the group consisting of a paper stock consistency sensor, a grammage sensor, a layer thickness sensor, and a mass flow per unit area sensor.

25. A paper quality control device for controlling at least one of the cross-machine direction profile and the machine direction profile of at least one quality feature of a paper web as it is being produced in a paper making machine, the paper quality control device comprising:

a controller for receiving signals from a sensor and for driving and controlling an actuator;

at least one actuator which is connected with the controller and is operable by the controller for influencing at least one of the cross-machine direction profile and the machine direction profile of the at least one quality feature of the web;

a first sensor adapted to and positioned for picking up a first measured signal of the cross-machine direction profile of a first quality feature of the paper web, the first sensor being connected with the controller for supplying a first signal to the controller;

a second sensor adapted to and positioned at a spaced position in the machine direction from the first sensor for picking up a second measured signal of the machine direction profile of the first quality feature of the web, the second sensor also being connected with the controller for supplying a second signal to the controller;

the controller receiving signals from the first and second sensors and being adapted to drive the actuator to adjust or control at least one of the cross-machine direction and machine direction profiles of the one quality feature of the web.

26. A method for control of one of a cross-machine direction profile and a machine direction profile of a quality feature of a paper web in a paper manufacturing process, the method comprising:

measuring at least one of a first cross machine direction profile and a first machine direction profile of the one quality feature at least one point on a paper making machine on which the process is performed;

picking up at a second point spaced in the machine direction from the first point at least one further measured variable that is characteristic of at least one of a second cross machine direction profile and a second machine direction profile of a second quality feature;

processing the measurements of the profiles; and

using the processed measurements for influencing at least one of the cross machine direction profile and the machine direction profile of one of the measured quality features in the paper manufacturing process.

27. The method of claim 26, further comprising splitting the measurements of the profiles in a computer into a machine direction component signal and a cross-machine direction component signal, and using the split signal for influencing the selected profile of the one measured quality feature.

28. The method of claim 26, further comprising feeding the machine direction component signal to a controller for the machine direction component and feeding the cross-machine direction component signal to a controller for the cross-machine direction component.

29. The method of claim 26, wherein the controller for the cross machine direction component operates a controlled consistency flowbox for influencing the cross machine direction profile.

30. The method of claim 29, wherein the controlled consistency flowbox, for the paper stock suspension comprises a plurality of dilution means feed lines and a control valve in each dilution means feed line;

the method further comprising controlling the valve in each of the dilution means feed lines for controlling the pulp consistency in each of the feed lines.

31. The method of claim 27, wherein the controlled consistency flowbox, for the paper stock suspension comprises a plurality of dilution means, feed lines and a control valve in each dilution means feed line;

the method further comprising controlling the valve in each of the dilution means feed lines for controlling the pulp consistency in each of the feed lines.

34. The method of claim 28, wherein the controller for the cross machine direction component operates a controlled consistency flowbox for influencing the cross machine direction profile.

32. A method for control of one of a cross-machine direction profile and a machine direction profile of a quality feature in a paper manufacturing process, the method comprising:

measuring at least two different profiles, each being spaced from the other in the machine direction having a respective cross machine direction component and a respective machine direction component, of at least one quality feature of a web being produced in a paper making machine;

processing the measured signals for calculating the pure cross machine direction profile and the pure machine direction profile of the at least one quality feature;

using the signals as to the profiles for influencing at least one of the cross machine direction profile and the machine direction profile of the at least one quality feature in the paper manufacturing process.

33. The method of claim 32, further comprising feeding the machine direction component signal to a controller for the machine direction component and feeding the cross-machine direction component signal to a controller for the cross machine direction component.