Claims
- 1. A method for regulation of the initial part of the dryer section in a paper machine having a press section in which moisture is removed from the paper web, and a dryer section in which the paper web is dried, and in which the paper web is passed from the press section into a first group of first drying cylinders forming a part of the dryer section, in which the paper web is dried against heated faces of the drying cylinders, the method comprising the steps of:measuring the surface temperatures of the first drying cylinders of the first group of drying cylinders in the dryer section; measuring the dry solids content/moisture content of the paper web and the temperature of the paper web upstream of said first drying cylinders, and in view of producing the desired running situation, based on the measured surface temperatures and dry solids content/moisture contents, regulating the surface temperatures of the first drying cylinders, the dry solids content/moisture content, and the temperature of the paper web before said first drying cylinders.
- 2. The method of claim 1 wherein, based on said measurements, the difference between the surface temperatures of the first drying cylinders of the first group of drying cylinders and the web temperature is regulated to a level lower than a preset value or a value determined by means of computing on the basis of the measurement results.
- 3. The method of claim 1 wherein, based on said measurements, the surface temperatures of the first cylinders are regulated to a level lower than the sum of the measured web temperature and a predetermined temperature or a temperature determined by means of computing.
- 4. The method of claim 1 wherein, based on said measurements, the temperature of the web is regulated to a level higher than the difference between the measured surface temperatures of the first cylinders and a predetermined temperature or a temperature determined by means of computing.
- 5. The method of claims 1 wherein the paper web to be dried is passed from the press section to the dryer section over an impingement drying unit into the first group of drying cylinders, and based on said measurement results, blow parameters of the impingement drying unit are regulated.
- 6. The method of claim 1 wherein, based on said measurement results, regulating at least one of a press load of a press in the press section, and at least one steam box in the press section.
- 7. The method of claim 1 wherein an additional group of drying cylinders follows the first group of drying cylinders, and wherein, based on said measurement results, regulating the difference of draw between the press section and the dryer section as well as the differences in draw between the first cylinders and the additional group of drying cylinders.
- 8. The method of claim 1 wherein an additional group of drying cylinders follows the first group of drying cylinders, and wherein, based on said measurement results, regulating the difference of draw between the first cylinders and the additional group of drying cylinders.
- 9. The method of claim 1 wherein reversing suction rolls are positioned between adjacent pairs of first drying cylinders, each reversing suction roll having a level of vacuum, and wherein a blow or suction box is positioned above each reversing suction roll, and, based on at least one of said measurements, controlling the level of vacuum in the reversing suction rolls, the capacity of the blow or suction box, or both.
- 10. The method of claim 1, further comprising the step of employing a multi-variable regulation and optimizing method, wherein the at least one input variable is selected from the group consisting of:the capacity of the steam box; the press load; the capacity of the impingement drying; and the heating capacity of the first cylinder; to thereby maintain the moisture content of the web and the temperature of the web and the temperature of the first cylinder at the desired level.
- 11. The method of claim 1 further comprising the step of optimizing at least one of the web moisture content and the press load, and differences in temperature between drying cylinders and the web temperature are optimized by adjusting at least one of the heating capacity of an impingement drying unit fitted before the first drying cylinders and the heating capacity of the first cylinder itself.
- 12. The method of claim 1 wherein, for the purpose of threading after a web break in the paper web, the surface temperatures of said first drying cylinders not covered by the web are measured, and, based on the measurement results obtained, regulating at least one ofthe surface temperatures of said first drying cylinders, the press load in at least one press in the press section, the levels of the steam boxes in the press section, and the blow parameters of the impingement drying unit, in order to provide a desired threading situation.
- 13. The method of claim 1 wherein the temperatures of said first drying cylinders are regulated after a web break by means of a separate steam valve and by means of a supply of water produced out of a cooling cylinder.
- 14. The method of claim 1 wherein the temperatures of said first drying cylinders are regulated after a web break by means of a supply of water produced out of a cooling cylinder.
- 15. The method of claim 13 wherein condensate obtained from a condenser of a steam system is used as cooling water.
- 16. The method of claim 14 wherein condensate obtained from a condenser of a steam system is used as cooling water.
- 17. An apparatus for regulation of the initial part of the dryer section in a paper machine having a press section and a dryer with a plurality of first drying cylinders, the apparatus comprising:measurement devices fitted in connection with the first drying cylinders in the dryer section for measurement of the surface temperatures of said first drying cylinders; a measurement device for measurement of the dry solids content/moisture content of the paper web and of the temperature of the paper web before said first drying cylinders; and a control device for regulation of at least one of the surface temperatures of said first drying cylinders, the dry solids content/moisture content, and the temperature of the paper web before said first drying cylinders, based on the measurement results obtained by means of the measurement devices, so as to produce the desired running situation.
- 18. The apparatus of claim 17 wherein the control device of the equipment comprises means for regulation on the basis of said measurement results obtained from the measurement devices of at least one ofthe press load in at least one press in the press section; the steam box/boxes; the impingement drying unit fitted before said first drying cylinders; and the differences of draw between the first groups of drying cylinders in the dryer section on the basis of said measurement results obtained from the measurement devices.
- 19. The apparatus of claim 17 wherein paper machine has reversing suction rolls between pairs of the first drying cylinders, each suction roll having a level of vacuum applied, and a blow or suction box is positioned to act on at least one of the first drying cylinders and the apparatus further comprises a controller for regulation of the vacuums in the reversing suction rolls, and the capacity of the at least one blow or suction box.
- 20. The apparatus of claim 17 wherein the equipment has been fitted to be used during threading taking place after a web break in the paper web so as to provide the desired threading situation.
- 21. The apparatus of claim 17 wherein the equipment comprises a control unit for keeping the difference between the surface temperatures of the first cylinders and the web temperature below a preset value or a value determined on the basis of the measurement results.
Priority Claims (1)
Number |
Date |
Country |
Kind |
982622 |
Dec 1998 |
FI |
|
CROSS REFERENCES TO RELATED APPLICATIONS
This application is a continuation of PCT application No. PCT/F199/00990, filed Nov. 29, 1999, and claims priority on Finnish Application No. 982622, Filed Dec. 4, 1998, the disclosures of both of which applications are incorporated by reference herein.
US Referenced Citations (11)
Foreign Referenced Citations (3)
Number |
Date |
Country |
0 796 587 |
Apr 1997 |
EP |
0 844 084 |
May 1998 |
EP |
0 908 555 |
Apr 1999 |
EP |
Non-Patent Literature Citations (5)
Entry |
International Search Report issued in PCT/FI99/00990. |
The National Board of Patents and Registration Official Action dated Jul. 15, 1999. |
The National Board of Patents and Registration Official Action of Approval dated Dec. 28, 1999. |
The National Board of Patents and Registration Communication dated Feb. 24, 2000. |
Paper Technology, Jun. 1998 Technical News, p. 17. |
Continuations (1)
|
Number |
Date |
Country |
Parent |
PCT/FI99/00990 |
Nov 1999 |
US |
Child |
09/867925 |
|
US |